Slashdot Mirror

When direct database access to the information you need isn't available, but web pages with the right data are, you might pursue "screen-scraping" -- fetching a web page and scanning its text for the appropriate pieces of text in order to do further processing. LWP (Library for WWW access in Perl) is a collection of module to help you do this. mir writes: " Perl & LWP is a solid, no-nonsense book that will teach you how to do screen-scraping using Perl. It describes how to automatically retrieve and use information from the web. An introduction to LWP and related modules from simple to advanced uses and various ways to extract information from the returned HTML." Perl & LWP author Sean M. Burke pages 264 publisher O'Reilly and Associates rating 9 reviewer mir ISBN 0596001789 summary Excellent introduction to extracting and processing information from web sites.

The good: The book has a nice style and good coverage of the subject, includes introduction to all the modules used, reference material and includes good, well-developed examples. I really liked the way the authors describe the basic methodology to develop screen-scraping code, from analyzing an HTML page to extracting and displaying only what you are interested in.

The bad: Not much is bad, really. Some chapters are a little dry, though, and sometimes the reference material could be better separated from the rest of the text. The book covers only simple access to web sites; I would have liked to see an example where the application engages in more dialogue with the server. In addition, the appendixes are not really useful. More Info:

If it had not been published by O'Reilly, Perl and LWP could have been titled Leveraging the Web: Object-Oriented techniques for information re-purposing, or Web Services, Generation 0. An even better title would have been Screen-scraping for fun and profit: one day we might all use Web Services and easily get the information we need from various providers using SOAP or REST, but in the meantime the common way to achieve this goal is just to write code to connect to a web server, retrieve a page and extract the information from the HTML. In short, "screen-scraping." This will teach you all about using Perl to get Web pages and extract their "substantifique moëlle" (the pith essence, the essentials) for your own usage. It showcases the power of Perl for that kind of job, from regular expressions to powerful CPAN modules.

At 200 pages, plus 40 pages of appendices and index, this one is part of that line of compact O'Reilly books which covers only a narrow topic in each volume but which covers those topics well. Just like Perl & XML , its target audience is Perl programmers who need to tackle a new domain. It gives them a toolbox and basic techniques that to provide a jump start and avoid many mistakes.

Perl & LWP starts from the basics: installing LWP, using LWP::Simple to retrieve a file from a URL, then goes on to a more complete description of the advanced LWP methods for dealing with forms and munging URLs. It continues with five chapters on how to process the HTML you get, using regular expressions, an HTML tokenizer and HTML::TreeBuilder, a powerful module that builds a tree from the HTML. It goes on with an explanation of how to allow your programs to access sites that require cookies, authentication or the use of a specific browser. The final chapter wraps it all up in a bigger example: a web-spider.

The book is well-written and to-the-point. It is structured in a way that mimics what a programmer new to the field would do: start from the docs for a module, play with it, write snippets of code that use the various functions of the module, then go on to coding real-life examples. I particularly liked the fact that the author often explains the whys, and not only the hows, of the various pieces of code he shows us.

It is interesting to note that going from regular expressions to ever more powerful modules is a path followed also by most Perl programmers, and even by the language itself: when Perl starts being applied to a new domain first there are no modules, then low-level ones start appearing, then, as the understanding of the problem grows, easier-to-use modules are written.

Finally I would like to thank the author for following his own advice by including interesting examples and above all for not including anything about retrieving stock-quotes.

Another recommended book on the subject is Network Programming with Perl by Lincoln D. Stein, which covers a wider subject but devotes 50 pages to this topic and is also very good.

Breakdown by chapter:

• 1. Introduction to Web Automation (15 pages): an overview of what this book will teach you, how to install Gisle Aas' LWP, some interesting words of caution about the brittleness of screen-scraping code, copyright issues and respect for the servers you are about to hammer, and finally a very simple example that shows the basic process of web automation.

  2. Web Basics (16p): describes how to use LWP::Simple, an easy way to do some simple processing.

  3. The LWP Class Model (17p): a slightly steeper read, closer to a reference than to a real introduction that lays out the ground work for the good stuff ahead.

  4. URLs (10p): another reference chapter, this one will teach you all you can do with URLs using the URI module. Although the chapter is clear and complete it includes little explanation as to why you will need to process URLs and it is not even mentioned in the introduction roadmap.

  5. Forms (28p): a complete and easy to read chapter. It includes a long description of HTML form fields that can be used as a reference, 2 fun examples (how to get the number of people living in any city in the US from the Census web site and how to check that your dream vanity plate is available in California) and how to use LWP to upload files to a server. It also describes the limits of the technique. I appreciated a very educative section showing how to go from a list of fields in a form to more and more useful code that queries that form.

  6. Simple HTML processing with Regular Expressions (15p): how to extract info from an HTML page using regexps. The chapter starts with short sections about various useful regexp features, then presents excellent advice on troubleshooting them, the limits of the technique and a series of examples. An interesting chapter, but read on for more powerful ways to process HTML. On the down side, I found the discussion of the s and m regexp modifiers a little confusing.

  7. HTML processing with Tokens (19p): using a real HTML parser is a better (safer) way to process HTML than regexps. This chapter uses HTML::TokeParser. It starts with a short, reference-type intro, then a detailed example. Another reference section describes the methods an alternate way of using the module, with short examples. This is the kind of reference I find the most useful, it is the simplest way to understand how to use a module.

  8. Tokenizing walkthrough (13p) a long Example showing step-by-step how to write a program that extracts data from a web site, using HTML::TokeParser. The explanations are very good, showing _why_ the code is built this way and including alternatives (both good and bad ones). This chapter describes really well the method readers can use to build their code.

  9. HTML processing with Trees (16p): even more powerful than an HTML tokenizer: HTML::TreeBuilder (written by the author of the book) builds a tree from the HTML. This chapter starts with a short reference section, then revisits 2 previous examples of extracting information from HTML using HTML::TreeBuilder.

  10. Modifying HTML with Trees (17p): More on the power of HTML::TreeBuilder: a reference/howto on the modification functions of HTML::TreeBuilder, with snippets of code for each function I really like HTML::TreeBuilder BTW, it is simple yet powerful.

  11. Cookies, Authentication and Advanced Requests (13p): Back to that LWP business... this chapter is simple and to-the-point: how to use cookies, authentication and referer to access even more web-sites. I just found that it lacked a description on how to code a complete session with cookies.

  12. Spiders (20p): a long example describing how to build a link-checking spider. It uses most of the techniques previously described in the book, plus some additional ones to deal with redirection and robots.txt files.

• Appendices

  I think the Appendices are actually the weakest part of the book, most of them are not really useful, apart from the ASCII table (every computer book should have an ASCII table IMHO ;--).

  • A. LWP modules (4p): the list and one line description of all modules in the LWP library, long and impressive! But not very useful,
  • B. HTTP status (2p): available elsewhere but still pretty useful,
  • C. Common MIME types (2p): lists both the usual extension and the MIME type,
  • D. Language Tags (2p): the author is a linguist ;--)
  • E. Common Content Encodings (2p): character set codes,
  • F. ASCII Table (13p): a very complete table, includes the ascii/unicode code, the corresponding HTML entity, description and glyph,
  • G. User's View of Object-Oriented Modules (11p): this is a very good idea. A lot of Perl programmers are not very familiar with OO, and in truth they don't need to be. They just need the basics of how to create an object in an existing class and call methods on it. I found the text too be sightly confusing though, in fact I believe it is a little too detailed and might confuse the reader.
  • Index (8p): I did not think the index was great (code is listed with references to 5 seemingly random pieces of code, type=file, HTML input element is listed twice, with and without the comma...), but this is not the kind of book where the index is the primary way to access the information. The Table of Content is complete and the chapters are focused enough that I have never needed to use the index.

You can purchase Perl & LWP from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.

Thanks to darrn chamberlain for an excellent review of the Lincoln Stein and Doug MacEachern book Writing Apache Modules with Perl and C. This is an excellent book for those considering working with Apache and mod_perl, and helpful for C programmers. Click below for more details. Writing Apache Modules with Perl and C author Li pages 724 publisher O'Reilly, ISBN: 156592567X rating 9.5/10 reviewer darren chamberlain ISBN summary Absolutely essential for anyone who is considering using Apache and mod_perl. C programmers may need more. The Scenario

If you're like me, your first introduction to Perl ^[?] was in the form of CGI ^[?] scripts. A few years ago, I inherited a few dozen ancient CGI scripts (Perl and otherwise) that required Immediate Attention. CGI led to Perl, and to Apache ^[?] ; Perl and Apache led, naturally enough, to mod_perl ^[?] , once I started hitting the performance bottlenecks inherenent in CGI programming. After researching mod_perl, building a mod_perl-enalbed Apache, and reading all the available online documentation, I got it up and running--and I was suitably impressed.

So, when O'Reilly ^[?] announced a book devoted to programming Apache with Perl, I was extremely excited. The book starts with an introduction and history of web programming, introduces CGI and other types of web programming (server API ^[?] 's, such as ISAPI and NSAPI; embedded processors, such as mod_perl, mod_dtcl, and mod_pyapache; FastCGI; Java ^[?] servlets ^[?] ; ActiveX ^[?] ; and client-side scripting languages, such as VBScript ^[?] and JavaScript ^[?] ), and then describes the Apache module architecture, using some simple examples ("Hello, World" in Perl and in C). Then it gets good, covering dynamically generated content; the hobgoblin of HTTP, state; and all the other stuff that gives CGI programmer nightmares (like authentication and authorization).

What's Bad?

Although the title reads '... with Perl and C', the emphasis is very obviously on Perl. The C API reference chapters (chapters 10 and 11, pages 505 through 631) are very thorough, but almost all the examples are in Perl only. In fact, the authors go so far as to recommend that almost all Apache modules be written in Perl, and not C, except for very small modules or modules that need that extra speed boost or small memory footprint of being compiled into the server (page 13: "Anything you can do with the C API you can do with mod_perl with less fuss and bother."). Their reasoning is sound: mod_perl modules and scripts require a server restart at most, and often not even that, while for C modules, Apache itself must be recompiled; but I was expecting more in this area, perhaps a larger section on using DSO. After the book was published, however, several of the Perl-only examples were ported to the C API, and are available for download.

A few of these examples have already been published, and in these cases the book is mostly redundant. Notably, the Apache::NavBar module (which Lincoln uses on the server in his lab) and the Apache::AdBlocker module (chapters 4 and 7), appeared in The Perl Journal last year (issues 12 and 11). This is not that big a deal, since both of these modules are incredibly useful and probably deserve to be published in a few more places, but two brand new modules would have been most welcome, especially since the book's target audience probably also reads The Perl Journal.

What's Good?

There's a lot to like here. Since I'm a Perl programmer by trade and disposition, I personally liked the fact that 99.9% of the examples were written in Perl. With only a few exceptions, the modules could be copied into the right locations and run immediately; the exceptions were the modules that made use of either other programs (Chapter 5's Hangman program which uses a relational database to store state information) or specialized Apache features (Chapter 7's Apache::AdBlocker module, which requires proxy functionality).

Much of the text and all of the source code is available on the web at www.modperl.com. Chapters 6, 7, 8, and 9 can be found on the web site for the book, as can all the Perl modules and some of the examples in functional form (Apache::Magic and hangman).

Chapter 9 is the key chapter, and the heart of the book. It describes in great detail all the Apache:: modules. If you use mod_perl at all, download and print this chapter. Memorize it. Use your favorite indexing script to make it searchable. Everything you need to know about mod_perl is here in this chapter.

The appendices are also excellent, although, because it is an Apache book, I would have figured that several of the sections would be regular chapters, and not relegated to the end. The appendices are divided pretty evenly between concentrating on Perl and on C, unlike most of the rest of the book.

So What's In It For Me?

Fortunately for people like me, there is a lot of information about mod_perl on the web; The Perl Journal has had several articles on it, WebMonkey has had an article or two, and so on. There is a comprehensive mod_perl developer's guide on the offical Apache/Perl site. Lincoln Stein uses it a lot on his site and in his software. And, of course, we have the man pages and perldocs. So why do we need a book?

A few reasons. First and foremost, few of those sources go into the kind of detail that this book does, while still being approachable. Second, the book focuses on Apache, programming Apache, and (to a lesser extent) programming applications on the web; Perl and C are the means here, not the end. The in-depth technical discussions are about Apache: how it translates URI's to filenames, how it handles subrequests and internal redirects, how it maps files to MIME types. It then presents techniques for usurping these functions, customizing each phase of the reponse process, and explains when and why you would want to do this, instead of letting Apache do it's own thing. Creating checksums on the fly, compressing and decompressing data, creating extremely flexible HTML preprocessors, and modifying outgoing and incoming headers are some just some of the given examples.

The reference chapters are probably the single most valuable thing about the book. If you are a Perl programmer on a budget, you can download chapter 9 from the web site, but the C programmers out there have to buy the book to get the C API refernce. The C reference is 2 chapters (126 pages) long, and covers all the functions in precise detail.

For those among you who are using Microsoft operating systems, the book pays special attention to building, installing, and configuring mod_perl and Apache on Win32 systems, where it is different from Unix and Unix-like systems. Most of the actual modules are very similar (except for the obvious ones, such as scripts that call sendmail and the scripts that access MySQL), but the installation and building of mod_perl (or ApacheModulePerl.dll) are very different. The process is described in enough detail to make it possible, without boring those readers to whom it is irrelevant.

Conclusion

Programming Apache/mod_perl without this book is like writing Perl without the camel book. It can be done, but it is much easier and more enjoyable with the book. The writing is clear, informative, straight-forward, and, at times, amusing. The authors are the definitive sources for information on mod_perl and CGI programming, and this is reflected in every aspect of the book. While not as definitive for C programmers, it is still the best Apache API reference out there, other than the actual source code itself.

Purchase this book at Amazon.

Errata Table of Contents

1. Server-Side Programming with Apache
2. A First Module
3. The Apache Module Architecture and API
4. Content Handlers
5. Maintaining State
6. Authentication and Authorization
7. Other Request Phases
8. Customizing the Apache Configuration Process
9. Perl API Reference Guide
10. C API Reference Guide, Part I
11. API Reference Guide, Part II

1. Standard Noncore Modules
2. Building and Installing mod_perl
3. Building Multifile C API Modules
4. Apache:: Modules Available on CPAN
5. Third-Party C Modules
6. HTML::Embperl--Embedding Perl Code in HTML

Thanks to darrn chamberlain for an excellent review of the Lincoln Stein and Doug MacEachern book Writing Apache Modules with Perl and C. This is an excellent book for those considering working with Apache and mod_perl, and helpful for C programmers. Click below for more details. Writing Apache Modules with Perl and C author Li pages 724 publisher O'Reilly, ISBN: 156592567X rating 9.5/10 reviewer darren chamberlain ISBN summary Absolutely essential for anyone who is considering using Apache and mod_perl. C programmers may need more. The Scenario

If you're like me, your first introduction to Perl ^[?] was in the form of CGI ^[?] scripts. A few years ago, I inherited a few dozen ancient CGI scripts (Perl and otherwise) that required Immediate Attention. CGI led to Perl, and to Apache ^[?] ; Perl and Apache led, naturally enough, to mod_perl ^[?] , once I started hitting the performance bottlenecks inherenent in CGI programming. After researching mod_perl, building a mod_perl-enalbed Apache, and reading all the available online documentation, I got it up and running--and I was suitably impressed.

So, when O'Reilly ^[?] announced a book devoted to programming Apache with Perl, I was extremely excited. The book starts with an introduction and history of web programming, introduces CGI and other types of web programming (server API ^[?] 's, such as ISAPI and NSAPI; embedded processors, such as mod_perl, mod_dtcl, and mod_pyapache; FastCGI; Java ^[?] servlets ^[?] ; ActiveX ^[?] ; and client-side scripting languages, such as VBScript ^[?] and JavaScript ^[?] ), and then describes the Apache module architecture, using some simple examples ("Hello, World" in Perl and in C). Then it gets good, covering dynamically generated content; the hobgoblin of HTTP, state; and all the other stuff that gives CGI programmer nightmares (like authentication and authorization).

What's Bad?

Although the title reads '... with Perl and C', the emphasis is very obviously on Perl. The C API reference chapters (chapters 10 and 11, pages 505 through 631) are very thorough, but almost all the examples are in Perl only. In fact, the authors go so far as to recommend that almost all Apache modules be written in Perl, and not C, except for very small modules or modules that need that extra speed boost or small memory footprint of being compiled into the server (page 13: "Anything you can do with the C API you can do with mod_perl with less fuss and bother."). Their reasoning is sound: mod_perl modules and scripts require a server restart at most, and often not even that, while for C modules, Apache itself must be recompiled; but I was expecting more in this area, perhaps a larger section on using DSO. After the book was published, however, several of the Perl-only examples were ported to the C API, and are available for download.

A few of these examples have already been published, and in these cases the book is mostly redundant. Notably, the Apache::NavBar module (which Lincoln uses on the server in his lab) and the Apache::AdBlocker module (chapters 4 and 7), appeared in The Perl Journal last year (issues 12 and 11). This is not that big a deal, since both of these modules are incredibly useful and probably deserve to be published in a few more places, but two brand new modules would have been most welcome, especially since the book's target audience probably also reads The Perl Journal.

What's Good?

There's a lot to like here. Since I'm a Perl programmer by trade and disposition, I personally liked the fact that 99.9% of the examples were written in Perl. With only a few exceptions, the modules could be copied into the right locations and run immediately; the exceptions were the modules that made use of either other programs (Chapter 5's Hangman program which uses a relational database to store state information) or specialized Apache features (Chapter 7's Apache::AdBlocker module, which requires proxy functionality).

Much of the text and all of the source code is available on the web at www.modperl.com. Chapters 6, 7, 8, and 9 can be found on the web site for the book, as can all the Perl modules and some of the examples in functional form (Apache::Magic and hangman).

Chapter 9 is the key chapter, and the heart of the book. It describes in great detail all the Apache:: modules. If you use mod_perl at all, download and print this chapter. Memorize it. Use your favorite indexing script to make it searchable. Everything you need to know about mod_perl is here in this chapter.

The appendices are also excellent, although, because it is an Apache book, I would have figured that several of the sections would be regular chapters, and not relegated to the end. The appendices are divided pretty evenly between concentrating on Perl and on C, unlike most of the rest of the book.

So What's In It For Me?

Fortunately for people like me, there is a lot of information about mod_perl on the web; The Perl Journal has had several articles on it, WebMonkey has had an article or two, and so on. There is a comprehensive mod_perl developer's guide on the offical Apache/Perl site. Lincoln Stein uses it a lot on his site and in his software. And, of course, we have the man pages and perldocs. So why do we need a book?

A few reasons. First and foremost, few of those sources go into the kind of detail that this book does, while still being approachable. Second, the book focuses on Apache, programming Apache, and (to a lesser extent) programming applications on the web; Perl and C are the means here, not the end. The in-depth technical discussions are about Apache: how it translates URI's to filenames, how it handles subrequests and internal redirects, how it maps files to MIME types. It then presents techniques for usurping these functions, customizing each phase of the reponse process, and explains when and why you would want to do this, instead of letting Apache do it's own thing. Creating checksums on the fly, compressing and decompressing data, creating extremely flexible HTML preprocessors, and modifying outgoing and incoming headers are some just some of the given examples.

The reference chapters are probably the single most valuable thing about the book. If you are a Perl programmer on a budget, you can download chapter 9 from the web site, but the C programmers out there have to buy the book to get the C API refernce. The C reference is 2 chapters (126 pages) long, and covers all the functions in precise detail.

For those among you who are using Microsoft operating systems, the book pays special attention to building, installing, and configuring mod_perl and Apache on Win32 systems, where it is different from Unix and Unix-like systems. Most of the actual modules are very similar (except for the obvious ones, such as scripts that call sendmail and the scripts that access MySQL), but the installation and building of mod_perl (or ApacheModulePerl.dll) are very different. The process is described in enough detail to make it possible, without boring those readers to whom it is irrelevant.

Conclusion

Programming Apache/mod_perl without this book is like writing Perl without the camel book. It can be done, but it is much easier and more enjoyable with the book. The writing is clear, informative, straight-forward, and, at times, amusing. The authors are the definitive sources for information on mod_perl and CGI programming, and this is reflected in every aspect of the book. While not as definitive for C programmers, it is still the best Apache API reference out there, other than the actual source code itself.

Purchase this book at Amazon.

Errata Table of Contents

1. Server-Side Programming with Apache
2. A First Module
3. The Apache Module Architecture and API
4. Content Handlers
5. Maintaining State
6. Authentication and Authorization
7. Other Request Phases
8. Customizing the Apache Configuration Process
9. Perl API Reference Guide
10. C API Reference Guide, Part I
11. API Reference Guide, Part II

1. Standard Noncore Modules
2. Building and Installing mod_perl
3. Building Multifile C API Modules
4. Apache:: Modules Available on CPAN
5. Third-Party C Modules
6. HTML::Embperl--Embedding Perl Code in HTML

Thanks to darrn chamberlain for an excellent review of the Lincoln Stein and Doug MacEachern book Writing Apache Modules with Perl and C. This is an excellent book for those considering working with Apache and mod_perl, and helpful for C programmers. Click below for more details. Writing Apache Modules with Perl and C author Li pages 724 publisher O'Reilly, ISBN: 156592567X rating 9.5/10 reviewer darren chamberlain ISBN summary Absolutely essential for anyone who is considering using Apache and mod_perl. C programmers may need more. The Scenario

If you're like me, your first introduction to Perl ^[?] was in the form of CGI ^[?] scripts. A few years ago, I inherited a few dozen ancient CGI scripts (Perl and otherwise) that required Immediate Attention. CGI led to Perl, and to Apache ^[?] ; Perl and Apache led, naturally enough, to mod_perl ^[?] , once I started hitting the performance bottlenecks inherenent in CGI programming. After researching mod_perl, building a mod_perl-enalbed Apache, and reading all the available online documentation, I got it up and running--and I was suitably impressed.

So, when O'Reilly ^[?] announced a book devoted to programming Apache with Perl, I was extremely excited. The book starts with an introduction and history of web programming, introduces CGI and other types of web programming (server API ^[?] 's, such as ISAPI and NSAPI; embedded processors, such as mod_perl, mod_dtcl, and mod_pyapache; FastCGI; Java ^[?] servlets ^[?] ; ActiveX ^[?] ; and client-side scripting languages, such as VBScript ^[?] and JavaScript ^[?] ), and then describes the Apache module architecture, using some simple examples ("Hello, World" in Perl and in C). Then it gets good, covering dynamically generated content; the hobgoblin of HTTP, state; and all the other stuff that gives CGI programmer nightmares (like authentication and authorization).

What's Bad?

Although the title reads '... with Perl and C', the emphasis is very obviously on Perl. The C API reference chapters (chapters 10 and 11, pages 505 through 631) are very thorough, but almost all the examples are in Perl only. In fact, the authors go so far as to recommend that almost all Apache modules be written in Perl, and not C, except for very small modules or modules that need that extra speed boost or small memory footprint of being compiled into the server (page 13: "Anything you can do with the C API you can do with mod_perl with less fuss and bother."). Their reasoning is sound: mod_perl modules and scripts require a server restart at most, and often not even that, while for C modules, Apache itself must be recompiled; but I was expecting more in this area, perhaps a larger section on using DSO. After the book was published, however, several of the Perl-only examples were ported to the C API, and are available for download.

A few of these examples have already been published, and in these cases the book is mostly redundant. Notably, the Apache::NavBar module (which Lincoln uses on the server in his lab) and the Apache::AdBlocker module (chapters 4 and 7), appeared in The Perl Journal last year (issues 12 and 11). This is not that big a deal, since both of these modules are incredibly useful and probably deserve to be published in a few more places, but two brand new modules would have been most welcome, especially since the book's target audience probably also reads The Perl Journal.

What's Good?

There's a lot to like here. Since I'm a Perl programmer by trade and disposition, I personally liked the fact that 99.9% of the examples were written in Perl. With only a few exceptions, the modules could be copied into the right locations and run immediately; the exceptions were the modules that made use of either other programs (Chapter 5's Hangman program which uses a relational database to store state information) or specialized Apache features (Chapter 7's Apache::AdBlocker module, which requires proxy functionality).

Much of the text and all of the source code is available on the web at www.modperl.com. Chapters 6, 7, 8, and 9 can be found on the web site for the book, as can all the Perl modules and some of the examples in functional form (Apache::Magic and hangman).

Chapter 9 is the key chapter, and the heart of the book. It describes in great detail all the Apache:: modules. If you use mod_perl at all, download and print this chapter. Memorize it. Use your favorite indexing script to make it searchable. Everything you need to know about mod_perl is here in this chapter.

The appendices are also excellent, although, because it is an Apache book, I would have figured that several of the sections would be regular chapters, and not relegated to the end. The appendices are divided pretty evenly between concentrating on Perl and on C, unlike most of the rest of the book.

So What's In It For Me?

Fortunately for people like me, there is a lot of information about mod_perl on the web; The Perl Journal has had several articles on it, WebMonkey has had an article or two, and so on. There is a comprehensive mod_perl developer's guide on the offical Apache/Perl site. Lincoln Stein uses it a lot on his site and in his software. And, of course, we have the man pages and perldocs. So why do we need a book?

A few reasons. First and foremost, few of those sources go into the kind of detail that this book does, while still being approachable. Second, the book focuses on Apache, programming Apache, and (to a lesser extent) programming applications on the web; Perl and C are the means here, not the end. The in-depth technical discussions are about Apache: how it translates URI's to filenames, how it handles subrequests and internal redirects, how it maps files to MIME types. It then presents techniques for usurping these functions, customizing each phase of the reponse process, and explains when and why you would want to do this, instead of letting Apache do it's own thing. Creating checksums on the fly, compressing and decompressing data, creating extremely flexible HTML preprocessors, and modifying outgoing and incoming headers are some just some of the given examples.

The reference chapters are probably the single most valuable thing about the book. If you are a Perl programmer on a budget, you can download chapter 9 from the web site, but the C programmers out there have to buy the book to get the C API refernce. The C reference is 2 chapters (126 pages) long, and covers all the functions in precise detail.

For those among you who are using Microsoft operating systems, the book pays special attention to building, installing, and configuring mod_perl and Apache on Win32 systems, where it is different from Unix and Unix-like systems. Most of the actual modules are very similar (except for the obvious ones, such as scripts that call sendmail and the scripts that access MySQL), but the installation and building of mod_perl (or ApacheModulePerl.dll) are very different. The process is described in enough detail to make it possible, without boring those readers to whom it is irrelevant.

Conclusion

Programming Apache/mod_perl without this book is like writing Perl without the camel book. It can be done, but it is much easier and more enjoyable with the book. The writing is clear, informative, straight-forward, and, at times, amusing. The authors are the definitive sources for information on mod_perl and CGI programming, and this is reflected in every aspect of the book. While not as definitive for C programmers, it is still the best Apache API reference out there, other than the actual source code itself.

Purchase this book at Amazon.

Errata Table of Contents

1. Server-Side Programming with Apache
2. A First Module
3. The Apache Module Architecture and API
4. Content Handlers
5. Maintaining State
6. Authentication and Authorization
7. Other Request Phases
8. Customizing the Apache Configuration Process
9. Perl API Reference Guide
10. C API Reference Guide, Part I
11. API Reference Guide, Part II

1. Standard Noncore Modules
2. Building and Installing mod_perl
3. Building Multifile C API Modules
4. Apache:: Modules Available on CPAN
5. Third-Party C Modules
6. HTML::Embperl--Embedding Perl Code in HTML

Thanks to darrn chamberlain for an excellent review of the Lincoln Stein and Doug MacEachern book Writing Apache Modules with Perl and C. This is an excellent book for those considering working with Apache and mod_perl, and helpful for C programmers. Click below for more details. Writing Apache Modules with Perl and C author Li pages 724 publisher O'Reilly, ISBN: 156592567X rating 9.5/10 reviewer darren chamberlain ISBN summary Absolutely essential for anyone who is considering using Apache and mod_perl. C programmers may need more. The Scenario

If you're like me, your first introduction to Perl ^[?] was in the form of CGI ^[?] scripts. A few years ago, I inherited a few dozen ancient CGI scripts (Perl and otherwise) that required Immediate Attention. CGI led to Perl, and to Apache ^[?] ; Perl and Apache led, naturally enough, to mod_perl ^[?] , once I started hitting the performance bottlenecks inherenent in CGI programming. After researching mod_perl, building a mod_perl-enalbed Apache, and reading all the available online documentation, I got it up and running--and I was suitably impressed.

So, when O'Reilly ^[?] announced a book devoted to programming Apache with Perl, I was extremely excited. The book starts with an introduction and history of web programming, introduces CGI and other types of web programming (server API ^[?] 's, such as ISAPI and NSAPI; embedded processors, such as mod_perl, mod_dtcl, and mod_pyapache; FastCGI; Java ^[?] servlets ^[?] ; ActiveX ^[?] ; and client-side scripting languages, such as VBScript ^[?] and JavaScript ^[?] ), and then describes the Apache module architecture, using some simple examples ("Hello, World" in Perl and in C). Then it gets good, covering dynamically generated content; the hobgoblin of HTTP, state; and all the other stuff that gives CGI programmer nightmares (like authentication and authorization).

What's Bad?

Although the title reads '... with Perl and C', the emphasis is very obviously on Perl. The C API reference chapters (chapters 10 and 11, pages 505 through 631) are very thorough, but almost all the examples are in Perl only. In fact, the authors go so far as to recommend that almost all Apache modules be written in Perl, and not C, except for very small modules or modules that need that extra speed boost or small memory footprint of being compiled into the server (page 13: "Anything you can do with the C API you can do with mod_perl with less fuss and bother."). Their reasoning is sound: mod_perl modules and scripts require a server restart at most, and often not even that, while for C modules, Apache itself must be recompiled; but I was expecting more in this area, perhaps a larger section on using DSO. After the book was published, however, several of the Perl-only examples were ported to the C API, and are available for download.

A few of these examples have already been published, and in these cases the book is mostly redundant. Notably, the Apache::NavBar module (which Lincoln uses on the server in his lab) and the Apache::AdBlocker module (chapters 4 and 7), appeared in The Perl Journal last year (issues 12 and 11). This is not that big a deal, since both of these modules are incredibly useful and probably deserve to be published in a few more places, but two brand new modules would have been most welcome, especially since the book's target audience probably also reads The Perl Journal.

What's Good?

There's a lot to like here. Since I'm a Perl programmer by trade and disposition, I personally liked the fact that 99.9% of the examples were written in Perl. With only a few exceptions, the modules could be copied into the right locations and run immediately; the exceptions were the modules that made use of either other programs (Chapter 5's Hangman program which uses a relational database to store state information) or specialized Apache features (Chapter 7's Apache::AdBlocker module, which requires proxy functionality).

Much of the text and all of the source code is available on the web at www.modperl.com. Chapters 6, 7, 8, and 9 can be found on the web site for the book, as can all the Perl modules and some of the examples in functional form (Apache::Magic and hangman).

Chapter 9 is the key chapter, and the heart of the book. It describes in great detail all the Apache:: modules. If you use mod_perl at all, download and print this chapter. Memorize it. Use your favorite indexing script to make it searchable. Everything you need to know about mod_perl is here in this chapter.

The appendices are also excellent, although, because it is an Apache book, I would have figured that several of the sections would be regular chapters, and not relegated to the end. The appendices are divided pretty evenly between concentrating on Perl and on C, unlike most of the rest of the book.

So What's In It For Me?

Fortunately for people like me, there is a lot of information about mod_perl on the web; The Perl Journal has had several articles on it, WebMonkey has had an article or two, and so on. There is a comprehensive mod_perl developer's guide on the offical Apache/Perl site. Lincoln Stein uses it a lot on his site and in his software. And, of course, we have the man pages and perldocs. So why do we need a book?

A few reasons. First and foremost, few of those sources go into the kind of detail that this book does, while still being approachable. Second, the book focuses on Apache, programming Apache, and (to a lesser extent) programming applications on the web; Perl and C are the means here, not the end. The in-depth technical discussions are about Apache: how it translates URI's to filenames, how it handles subrequests and internal redirects, how it maps files to MIME types. It then presents techniques for usurping these functions, customizing each phase of the reponse process, and explains when and why you would want to do this, instead of letting Apache do it's own thing. Creating checksums on the fly, compressing and decompressing data, creating extremely flexible HTML preprocessors, and modifying outgoing and incoming headers are some just some of the given examples.

The reference chapters are probably the single most valuable thing about the book. If you are a Perl programmer on a budget, you can download chapter 9 from the web site, but the C programmers out there have to buy the book to get the C API refernce. The C reference is 2 chapters (126 pages) long, and covers all the functions in precise detail.

For those among you who are using Microsoft operating systems, the book pays special attention to building, installing, and configuring mod_perl and Apache on Win32 systems, where it is different from Unix and Unix-like systems. Most of the actual modules are very similar (except for the obvious ones, such as scripts that call sendmail and the scripts that access MySQL), but the installation and building of mod_perl (or ApacheModulePerl.dll) are very different. The process is described in enough detail to make it possible, without boring those readers to whom it is irrelevant.

Conclusion

Programming Apache/mod_perl without this book is like writing Perl without the camel book. It can be done, but it is much easier and more enjoyable with the book. The writing is clear, informative, straight-forward, and, at times, amusing. The authors are the definitive sources for information on mod_perl and CGI programming, and this is reflected in every aspect of the book. While not as definitive for C programmers, it is still the best Apache API reference out there, other than the actual source code itself.

Purchase this book at Amazon.

Errata Table of Contents

1. Server-Side Programming with Apache
2. A First Module
3. The Apache Module Architecture and API
4. Content Handlers
5. Maintaining State
6. Authentication and Authorization
7. Other Request Phases
8. Customizing the Apache Configuration Process
9. Perl API Reference Guide
10. C API Reference Guide, Part I
11. API Reference Guide, Part II

1. Standard Noncore Modules
2. Building and Installing mod_perl
3. Building Multifile C API Modules
4. Apache:: Modules Available on CPAN
5. Third-Party C Modules
6. HTML::Embperl--Embedding Perl Code in HTML

Thanks to darrn chamberlain for an excellent review of the Lincoln Stein and Doug MacEachern book Writing Apache Modules with Perl and C. This is an excellent book for those considering working with Apache and mod_perl, and helpful for C programmers. Click below for more details. Writing Apache Modules with Perl and C author Li pages 724 publisher O'Reilly, ISBN: 156592567X rating 9.5/10 reviewer darren chamberlain ISBN summary Absolutely essential for anyone who is considering using Apache and mod_perl. C programmers may need more. The Scenario

If you're like me, your first introduction to Perl ^[?] was in the form of CGI ^[?] scripts. A few years ago, I inherited a few dozen ancient CGI scripts (Perl and otherwise) that required Immediate Attention. CGI led to Perl, and to Apache ^[?] ; Perl and Apache led, naturally enough, to mod_perl ^[?] , once I started hitting the performance bottlenecks inherenent in CGI programming. After researching mod_perl, building a mod_perl-enalbed Apache, and reading all the available online documentation, I got it up and running--and I was suitably impressed.

So, when O'Reilly ^[?] announced a book devoted to programming Apache with Perl, I was extremely excited. The book starts with an introduction and history of web programming, introduces CGI and other types of web programming (server API ^[?] 's, such as ISAPI and NSAPI; embedded processors, such as mod_perl, mod_dtcl, and mod_pyapache; FastCGI; Java ^[?] servlets ^[?] ; ActiveX ^[?] ; and client-side scripting languages, such as VBScript ^[?] and JavaScript ^[?] ), and then describes the Apache module architecture, using some simple examples ("Hello, World" in Perl and in C). Then it gets good, covering dynamically generated content; the hobgoblin of HTTP, state; and all the other stuff that gives CGI programmer nightmares (like authentication and authorization).

What's Bad?

Although the title reads '... with Perl and C', the emphasis is very obviously on Perl. The C API reference chapters (chapters 10 and 11, pages 505 through 631) are very thorough, but almost all the examples are in Perl only. In fact, the authors go so far as to recommend that almost all Apache modules be written in Perl, and not C, except for very small modules or modules that need that extra speed boost or small memory footprint of being compiled into the server (page 13: "Anything you can do with the C API you can do with mod_perl with less fuss and bother."). Their reasoning is sound: mod_perl modules and scripts require a server restart at most, and often not even that, while for C modules, Apache itself must be recompiled; but I was expecting more in this area, perhaps a larger section on using DSO. After the book was published, however, several of the Perl-only examples were ported to the C API, and are available for download.

A few of these examples have already been published, and in these cases the book is mostly redundant. Notably, the Apache::NavBar module (which Lincoln uses on the server in his lab) and the Apache::AdBlocker module (chapters 4 and 7), appeared in The Perl Journal last year (issues 12 and 11). This is not that big a deal, since both of these modules are incredibly useful and probably deserve to be published in a few more places, but two brand new modules would have been most welcome, especially since the book's target audience probably also reads The Perl Journal.

What's Good?

There's a lot to like here. Since I'm a Perl programmer by trade and disposition, I personally liked the fact that 99.9% of the examples were written in Perl. With only a few exceptions, the modules could be copied into the right locations and run immediately; the exceptions were the modules that made use of either other programs (Chapter 5's Hangman program which uses a relational database to store state information) or specialized Apache features (Chapter 7's Apache::AdBlocker module, which requires proxy functionality).

Much of the text and all of the source code is available on the web at www.modperl.com. Chapters 6, 7, 8, and 9 can be found on the web site for the book, as can all the Perl modules and some of the examples in functional form (Apache::Magic and hangman).

Chapter 9 is the key chapter, and the heart of the book. It describes in great detail all the Apache:: modules. If you use mod_perl at all, download and print this chapter. Memorize it. Use your favorite indexing script to make it searchable. Everything you need to know about mod_perl is here in this chapter.

The appendices are also excellent, although, because it is an Apache book, I would have figured that several of the sections would be regular chapters, and not relegated to the end. The appendices are divided pretty evenly between concentrating on Perl and on C, unlike most of the rest of the book.

So What's In It For Me?

Fortunately for people like me, there is a lot of information about mod_perl on the web; The Perl Journal has had several articles on it, WebMonkey has had an article or two, and so on. There is a comprehensive mod_perl developer's guide on the offical Apache/Perl site. Lincoln Stein uses it a lot on his site and in his software. And, of course, we have the man pages and perldocs. So why do we need a book?

A few reasons. First and foremost, few of those sources go into the kind of detail that this book does, while still being approachable. Second, the book focuses on Apache, programming Apache, and (to a lesser extent) programming applications on the web; Perl and C are the means here, not the end. The in-depth technical discussions are about Apache: how it translates URI's to filenames, how it handles subrequests and internal redirects, how it maps files to MIME types. It then presents techniques for usurping these functions, customizing each phase of the reponse process, and explains when and why you would want to do this, instead of letting Apache do it's own thing. Creating checksums on the fly, compressing and decompressing data, creating extremely flexible HTML preprocessors, and modifying outgoing and incoming headers are some just some of the given examples.

The reference chapters are probably the single most valuable thing about the book. If you are a Perl programmer on a budget, you can download chapter 9 from the web site, but the C programmers out there have to buy the book to get the C API refernce. The C reference is 2 chapters (126 pages) long, and covers all the functions in precise detail.

For those among you who are using Microsoft operating systems, the book pays special attention to building, installing, and configuring mod_perl and Apache on Win32 systems, where it is different from Unix and Unix-like systems. Most of the actual modules are very similar (except for the obvious ones, such as scripts that call sendmail and the scripts that access MySQL), but the installation and building of mod_perl (or ApacheModulePerl.dll) are very different. The process is described in enough detail to make it possible, without boring those readers to whom it is irrelevant.

Conclusion

Programming Apache/mod_perl without this book is like writing Perl without the camel book. It can be done, but it is much easier and more enjoyable with the book. The writing is clear, informative, straight-forward, and, at times, amusing. The authors are the definitive sources for information on mod_perl and CGI programming, and this is reflected in every aspect of the book. While not as definitive for C programmers, it is still the best Apache API reference out there, other than the actual source code itself.

Purchase this book at Amazon.

Errata Table of Contents

1. Server-Side Programming with Apache
2. A First Module
3. The Apache Module Architecture and API
4. Content Handlers
5. Maintaining State
6. Authentication and Authorization
7. Other Request Phases
8. Customizing the Apache Configuration Process
9. Perl API Reference Guide
10. C API Reference Guide, Part I
11. API Reference Guide, Part II

1. Standard Noncore Modules
2. Building and Installing mod_perl
3. Building Multifile C API Modules
4. Apache:: Modules Available on CPAN
5. Third-Party C Modules
6. HTML::Embperl--Embedding Perl Code in HTML

Thanks to darrn chamberlain for an excellent review of the Lincoln Stein and Doug MacEachern book Writing Apache Modules with Perl and C. This is an excellent book for those considering working with Apache and mod_perl, and helpful for C programmers. Click below for more details. Writing Apache Modules with Perl and C author Li pages 724 publisher O'Reilly, ISBN: 156592567X rating 9.5/10 reviewer darren chamberlain ISBN summary Absolutely essential for anyone who is considering using Apache and mod_perl. C programmers may need more. The Scenario

If you're like me, your first introduction to Perl ^[?] was in the form of CGI ^[?] scripts. A few years ago, I inherited a few dozen ancient CGI scripts (Perl and otherwise) that required Immediate Attention. CGI led to Perl, and to Apache ^[?] ; Perl and Apache led, naturally enough, to mod_perl ^[?] , once I started hitting the performance bottlenecks inherenent in CGI programming. After researching mod_perl, building a mod_perl-enalbed Apache, and reading all the available online documentation, I got it up and running--and I was suitably impressed.

So, when O'Reilly ^[?] announced a book devoted to programming Apache with Perl, I was extremely excited. The book starts with an introduction and history of web programming, introduces CGI and other types of web programming (server API ^[?] 's, such as ISAPI and NSAPI; embedded processors, such as mod_perl, mod_dtcl, and mod_pyapache; FastCGI; Java ^[?] servlets ^[?] ; ActiveX ^[?] ; and client-side scripting languages, such as VBScript ^[?] and JavaScript ^[?] ), and then describes the Apache module architecture, using some simple examples ("Hello, World" in Perl and in C). Then it gets good, covering dynamically generated content; the hobgoblin of HTTP, state; and all the other stuff that gives CGI programmer nightmares (like authentication and authorization).

What's Bad?

Although the title reads '... with Perl and C', the emphasis is very obviously on Perl. The C API reference chapters (chapters 10 and 11, pages 505 through 631) are very thorough, but almost all the examples are in Perl only. In fact, the authors go so far as to recommend that almost all Apache modules be written in Perl, and not C, except for very small modules or modules that need that extra speed boost or small memory footprint of being compiled into the server (page 13: "Anything you can do with the C API you can do with mod_perl with less fuss and bother."). Their reasoning is sound: mod_perl modules and scripts require a server restart at most, and often not even that, while for C modules, Apache itself must be recompiled; but I was expecting more in this area, perhaps a larger section on using DSO. After the book was published, however, several of the Perl-only examples were ported to the C API, and are available for download.

A few of these examples have already been published, and in these cases the book is mostly redundant. Notably, the Apache::NavBar module (which Lincoln uses on the server in his lab) and the Apache::AdBlocker module (chapters 4 and 7), appeared in The Perl Journal last year (issues 12 and 11). This is not that big a deal, since both of these modules are incredibly useful and probably deserve to be published in a few more places, but two brand new modules would have been most welcome, especially since the book's target audience probably also reads The Perl Journal.

What's Good?

There's a lot to like here. Since I'm a Perl programmer by trade and disposition, I personally liked the fact that 99.9% of the examples were written in Perl. With only a few exceptions, the modules could be copied into the right locations and run immediately; the exceptions were the modules that made use of either other programs (Chapter 5's Hangman program which uses a relational database to store state information) or specialized Apache features (Chapter 7's Apache::AdBlocker module, which requires proxy functionality).

Much of the text and all of the source code is available on the web at www.modperl.com. Chapters 6, 7, 8, and 9 can be found on the web site for the book, as can all the Perl modules and some of the examples in functional form (Apache::Magic and hangman).

Chapter 9 is the key chapter, and the heart of the book. It describes in great detail all the Apache:: modules. If you use mod_perl at all, download and print this chapter. Memorize it. Use your favorite indexing script to make it searchable. Everything you need to know about mod_perl is here in this chapter.

The appendices are also excellent, although, because it is an Apache book, I would have figured that several of the sections would be regular chapters, and not relegated to the end. The appendices are divided pretty evenly between concentrating on Perl and on C, unlike most of the rest of the book.

So What's In It For Me?

Fortunately for people like me, there is a lot of information about mod_perl on the web; The Perl Journal has had several articles on it, WebMonkey has had an article or two, and so on. There is a comprehensive mod_perl developer's guide on the offical Apache/Perl site. Lincoln Stein uses it a lot on his site and in his software. And, of course, we have the man pages and perldocs. So why do we need a book?

A few reasons. First and foremost, few of those sources go into the kind of detail that this book does, while still being approachable. Second, the book focuses on Apache, programming Apache, and (to a lesser extent) programming applications on the web; Perl and C are the means here, not the end. The in-depth technical discussions are about Apache: how it translates URI's to filenames, how it handles subrequests and internal redirects, how it maps files to MIME types. It then presents techniques for usurping these functions, customizing each phase of the reponse process, and explains when and why you would want to do this, instead of letting Apache do it's own thing. Creating checksums on the fly, compressing and decompressing data, creating extremely flexible HTML preprocessors, and modifying outgoing and incoming headers are some just some of the given examples.

The reference chapters are probably the single most valuable thing about the book. If you are a Perl programmer on a budget, you can download chapter 9 from the web site, but the C programmers out there have to buy the book to get the C API refernce. The C reference is 2 chapters (126 pages) long, and covers all the functions in precise detail.

For those among you who are using Microsoft operating systems, the book pays special attention to building, installing, and configuring mod_perl and Apache on Win32 systems, where it is different from Unix and Unix-like systems. Most of the actual modules are very similar (except for the obvious ones, such as scripts that call sendmail and the scripts that access MySQL), but the installation and building of mod_perl (or ApacheModulePerl.dll) are very different. The process is described in enough detail to make it possible, without boring those readers to whom it is irrelevant.

Conclusion

Programming Apache/mod_perl without this book is like writing Perl without the camel book. It can be done, but it is much easier and more enjoyable with the book. The writing is clear, informative, straight-forward, and, at times, amusing. The authors are the definitive sources for information on mod_perl and CGI programming, and this is reflected in every aspect of the book. While not as definitive for C programmers, it is still the best Apache API reference out there, other than the actual source code itself.

Purchase this book at Amazon.

Errata Table of Contents

1. Server-Side Programming with Apache
2. A First Module
3. The Apache Module Architecture and API
4. Content Handlers
5. Maintaining State
6. Authentication and Authorization
7. Other Request Phases
8. Customizing the Apache Configuration Process
9. Perl API Reference Guide
10. C API Reference Guide, Part I
11. API Reference Guide, Part II

1. Standard Noncore Modules
2. Building and Installing mod_perl
3. Building Multifile C API Modules
4. Apache:: Modules Available on CPAN
5. Third-Party C Modules
6. HTML::Embperl--Embedding Perl Code in HTML

Thanks to darrn chamberlain for an excellent review of the Lincoln Stein and Doug MacEachern book Writing Apache Modules with Perl and C. This is an excellent book for those considering working with Apache and mod_perl, and helpful for C programmers. Click below for more details. Writing Apache Modules with Perl and C author Li pages 724 publisher O'Reilly, ISBN: 156592567X rating 9.5/10 reviewer darren chamberlain ISBN summary Absolutely essential for anyone who is considering using Apache and mod_perl. C programmers may need more. The Scenario

If you're like me, your first introduction to Perl ^[?] was in the form of CGI ^[?] scripts. A few years ago, I inherited a few dozen ancient CGI scripts (Perl and otherwise) that required Immediate Attention. CGI led to Perl, and to Apache ^[?] ; Perl and Apache led, naturally enough, to mod_perl ^[?] , once I started hitting the performance bottlenecks inherenent in CGI programming. After researching mod_perl, building a mod_perl-enalbed Apache, and reading all the available online documentation, I got it up and running--and I was suitably impressed.

So, when O'Reilly ^[?] announced a book devoted to programming Apache with Perl, I was extremely excited. The book starts with an introduction and history of web programming, introduces CGI and other types of web programming (server API ^[?] 's, such as ISAPI and NSAPI; embedded processors, such as mod_perl, mod_dtcl, and mod_pyapache; FastCGI; Java ^[?] servlets ^[?] ; ActiveX ^[?] ; and client-side scripting languages, such as VBScript ^[?] and JavaScript ^[?] ), and then describes the Apache module architecture, using some simple examples ("Hello, World" in Perl and in C). Then it gets good, covering dynamically generated content; the hobgoblin of HTTP, state; and all the other stuff that gives CGI programmer nightmares (like authentication and authorization).

What's Bad?

Although the title reads '... with Perl and C', the emphasis is very obviously on Perl. The C API reference chapters (chapters 10 and 11, pages 505 through 631) are very thorough, but almost all the examples are in Perl only. In fact, the authors go so far as to recommend that almost all Apache modules be written in Perl, and not C, except for very small modules or modules that need that extra speed boost or small memory footprint of being compiled into the server (page 13: "Anything you can do with the C API you can do with mod_perl with less fuss and bother."). Their reasoning is sound: mod_perl modules and scripts require a server restart at most, and often not even that, while for C modules, Apache itself must be recompiled; but I was expecting more in this area, perhaps a larger section on using DSO. After the book was published, however, several of the Perl-only examples were ported to the C API, and are available for download.

A few of these examples have already been published, and in these cases the book is mostly redundant. Notably, the Apache::NavBar module (which Lincoln uses on the server in his lab) and the Apache::AdBlocker module (chapters 4 and 7), appeared in The Perl Journal last year (issues 12 and 11). This is not that big a deal, since both of these modules are incredibly useful and probably deserve to be published in a few more places, but two brand new modules would have been most welcome, especially since the book's target audience probably also reads The Perl Journal.

What's Good?

There's a lot to like here. Since I'm a Perl programmer by trade and disposition, I personally liked the fact that 99.9% of the examples were written in Perl. With only a few exceptions, the modules could be copied into the right locations and run immediately; the exceptions were the modules that made use of either other programs (Chapter 5's Hangman program which uses a relational database to store state information) or specialized Apache features (Chapter 7's Apache::AdBlocker module, which requires proxy functionality).

Much of the text and all of the source code is available on the web at www.modperl.com. Chapters 6, 7, 8, and 9 can be found on the web site for the book, as can all the Perl modules and some of the examples in functional form (Apache::Magic and hangman).

Chapter 9 is the key chapter, and the heart of the book. It describes in great detail all the Apache:: modules. If you use mod_perl at all, download and print this chapter. Memorize it. Use your favorite indexing script to make it searchable. Everything you need to know about mod_perl is here in this chapter.

The appendices are also excellent, although, because it is an Apache book, I would have figured that several of the sections would be regular chapters, and not relegated to the end. The appendices are divided pretty evenly between concentrating on Perl and on C, unlike most of the rest of the book.

So What's In It For Me?

Fortunately for people like me, there is a lot of information about mod_perl on the web; The Perl Journal has had several articles on it, WebMonkey has had an article or two, and so on. There is a comprehensive mod_perl developer's guide on the offical Apache/Perl site. Lincoln Stein uses it a lot on his site and in his software. And, of course, we have the man pages and perldocs. So why do we need a book?

A few reasons. First and foremost, few of those sources go into the kind of detail that this book does, while still being approachable. Second, the book focuses on Apache, programming Apache, and (to a lesser extent) programming applications on the web; Perl and C are the means here, not the end. The in-depth technical discussions are about Apache: how it translates URI's to filenames, how it handles subrequests and internal redirects, how it maps files to MIME types. It then presents techniques for usurping these functions, customizing each phase of the reponse process, and explains when and why you would want to do this, instead of letting Apache do it's own thing. Creating checksums on the fly, compressing and decompressing data, creating extremely flexible HTML preprocessors, and modifying outgoing and incoming headers are some just some of the given examples.

The reference chapters are probably the single most valuable thing about the book. If you are a Perl programmer on a budget, you can download chapter 9 from the web site, but the C programmers out there have to buy the book to get the C API refernce. The C reference is 2 chapters (126 pages) long, and covers all the functions in precise detail.

For those among you who are using Microsoft operating systems, the book pays special attention to building, installing, and configuring mod_perl and Apache on Win32 systems, where it is different from Unix and Unix-like systems. Most of the actual modules are very similar (except for the obvious ones, such as scripts that call sendmail and the scripts that access MySQL), but the installation and building of mod_perl (or ApacheModulePerl.dll) are very different. The process is described in enough detail to make it possible, without boring those readers to whom it is irrelevant.

Conclusion

Programming Apache/mod_perl without this book is like writing Perl without the camel book. It can be done, but it is much easier and more enjoyable with the book. The writing is clear, informative, straight-forward, and, at times, amusing. The authors are the definitive sources for information on mod_perl and CGI programming, and this is reflected in every aspect of the book. While not as definitive for C programmers, it is still the best Apache API reference out there, other than the actual source code itself.

Purchase this book at Amazon.

Errata Table of Contents

1. Server-Side Programming with Apache
2. A First Module
3. The Apache Module Architecture and API
4. Content Handlers
5. Maintaining State
6. Authentication and Authorization
7. Other Request Phases
8. Customizing the Apache Configuration Process
9. Perl API Reference Guide
10. C API Reference Guide, Part I
11. API Reference Guide, Part II

1. Standard Noncore Modules
2. Building and Installing mod_perl
3. Building Multifile C API Modules
4. Apache:: Modules Available on CPAN
5. Third-Party C Modules
6. HTML::Embperl--Embedding Perl Code in HTML

Thanks to darrn chamberlain for an excellent review of the Lincoln Stein and Doug MacEachern book Writing Apache Modules with Perl and C. This is an excellent book for those considering working with Apache and mod_perl, and helpful for C programmers. Click below for more details. Writing Apache Modules with Perl and C author Li pages 724 publisher O'Reilly, ISBN: 156592567X rating 9.5/10 reviewer darren chamberlain ISBN summary Absolutely essential for anyone who is considering using Apache and mod_perl. C programmers may need more. The Scenario

If you're like me, your first introduction to Perl ^[?] was in the form of CGI ^[?] scripts. A few years ago, I inherited a few dozen ancient CGI scripts (Perl and otherwise) that required Immediate Attention. CGI led to Perl, and to Apache ^[?] ; Perl and Apache led, naturally enough, to mod_perl ^[?] , once I started hitting the performance bottlenecks inherenent in CGI programming. After researching mod_perl, building a mod_perl-enalbed Apache, and reading all the available online documentation, I got it up and running--and I was suitably impressed.

So, when O'Reilly ^[?] announced a book devoted to programming Apache with Perl, I was extremely excited. The book starts with an introduction and history of web programming, introduces CGI and other types of web programming (server API ^[?] 's, such as ISAPI and NSAPI; embedded processors, such as mod_perl, mod_dtcl, and mod_pyapache; FastCGI; Java ^[?] servlets ^[?] ; ActiveX ^[?] ; and client-side scripting languages, such as VBScript ^[?] and JavaScript ^[?] ), and then describes the Apache module architecture, using some simple examples ("Hello, World" in Perl and in C). Then it gets good, covering dynamically generated content; the hobgoblin of HTTP, state; and all the other stuff that gives CGI programmer nightmares (like authentication and authorization).

What's Bad?

Although the title reads '... with Perl and C', the emphasis is very obviously on Perl. The C API reference chapters (chapters 10 and 11, pages 505 through 631) are very thorough, but almost all the examples are in Perl only. In fact, the authors go so far as to recommend that almost all Apache modules be written in Perl, and not C, except for very small modules or modules that need that extra speed boost or small memory footprint of being compiled into the server (page 13: "Anything you can do with the C API you can do with mod_perl with less fuss and bother."). Their reasoning is sound: mod_perl modules and scripts require a server restart at most, and often not even that, while for C modules, Apache itself must be recompiled; but I was expecting more in this area, perhaps a larger section on using DSO. After the book was published, however, several of the Perl-only examples were ported to the C API, and are available for download.

A few of these examples have already been published, and in these cases the book is mostly redundant. Notably, the Apache::NavBar module (which Lincoln uses on the server in his lab) and the Apache::AdBlocker module (chapters 4 and 7), appeared in The Perl Journal last year (issues 12 and 11). This is not that big a deal, since both of these modules are incredibly useful and probably deserve to be published in a few more places, but two brand new modules would have been most welcome, especially since the book's target audience probably also reads The Perl Journal.

What's Good?

There's a lot to like here. Since I'm a Perl programmer by trade and disposition, I personally liked the fact that 99.9% of the examples were written in Perl. With only a few exceptions, the modules could be copied into the right locations and run immediately; the exceptions were the modules that made use of either other programs (Chapter 5's Hangman program which uses a relational database to store state information) or specialized Apache features (Chapter 7's Apache::AdBlocker module, which requires proxy functionality).

Much of the text and all of the source code is available on the web at www.modperl.com. Chapters 6, 7, 8, and 9 can be found on the web site for the book, as can all the Perl modules and some of the examples in functional form (Apache::Magic and hangman).

Chapter 9 is the key chapter, and the heart of the book. It describes in great detail all the Apache:: modules. If you use mod_perl at all, download and print this chapter. Memorize it. Use your favorite indexing script to make it searchable. Everything you need to know about mod_perl is here in this chapter.

The appendices are also excellent, although, because it is an Apache book, I would have figured that several of the sections would be regular chapters, and not relegated to the end. The appendices are divided pretty evenly between concentrating on Perl and on C, unlike most of the rest of the book.

So What's In It For Me?

Fortunately for people like me, there is a lot of information about mod_perl on the web; The Perl Journal has had several articles on it, WebMonkey has had an article or two, and so on. There is a comprehensive mod_perl developer's guide on the offical Apache/Perl site. Lincoln Stein uses it a lot on his site and in his software. And, of course, we have the man pages and perldocs. So why do we need a book?

A few reasons. First and foremost, few of those sources go into the kind of detail that this book does, while still being approachable. Second, the book focuses on Apache, programming Apache, and (to a lesser extent) programming applications on the web; Perl and C are the means here, not the end. The in-depth technical discussions are about Apache: how it translates URI's to filenames, how it handles subrequests and internal redirects, how it maps files to MIME types. It then presents techniques for usurping these functions, customizing each phase of the reponse process, and explains when and why you would want to do this, instead of letting Apache do it's own thing. Creating checksums on the fly, compressing and decompressing data, creating extremely flexible HTML preprocessors, and modifying outgoing and incoming headers are some just some of the given examples.

The reference chapters are probably the single most valuable thing about the book. If you are a Perl programmer on a budget, you can download chapter 9 from the web site, but the C programmers out there have to buy the book to get the C API refernce. The C reference is 2 chapters (126 pages) long, and covers all the functions in precise detail.

For those among you who are using Microsoft operating systems, the book pays special attention to building, installing, and configuring mod_perl and Apache on Win32 systems, where it is different from Unix and Unix-like systems. Most of the actual modules are very similar (except for the obvious ones, such as scripts that call sendmail and the scripts that access MySQL), but the installation and building of mod_perl (or ApacheModulePerl.dll) are very different. The process is described in enough detail to make it possible, without boring those readers to whom it is irrelevant.

Conclusion

Programming Apache/mod_perl without this book is like writing Perl without the camel book. It can be done, but it is much easier and more enjoyable with the book. The writing is clear, informative, straight-forward, and, at times, amusing. The authors are the definitive sources for information on mod_perl and CGI programming, and this is reflected in every aspect of the book. While not as definitive for C programmers, it is still the best Apache API reference out there, other than the actual source code itself.

Purchase this book at Amazon.

Errata Table of Contents

1. Server-Side Programming with Apache
2. A First Module
3. The Apache Module Architecture and API
4. Content Handlers
5. Maintaining State
6. Authentication and Authorization
7. Other Request Phases
8. Customizing the Apache Configuration Process
9. Perl API Reference Guide
10. C API Reference Guide, Part I
11. API Reference Guide, Part II

1. Standard Noncore Modules
2. Building and Installing mod_perl
3. Building Multifile C API Modules
4. Apache:: Modules Available on CPAN
5. Third-Party C Modules
6. HTML::Embperl--Embedding Perl Code in HTML

Thanks to darrn chamberlain for an excellent review of the Lincoln Stein and Doug MacEachern book Writing Apache Modules with Perl and C. This is an excellent book for those considering working with Apache and mod_perl, and helpful for C programmers. Click below for more details. Writing Apache Modules with Perl and C author Li pages 724 publisher O'Reilly, ISBN: 156592567X rating 9.5/10 reviewer darren chamberlain ISBN summary Absolutely essential for anyone who is considering using Apache and mod_perl. C programmers may need more. The Scenario

If you're like me, your first introduction to Perl ^[?] was in the form of CGI ^[?] scripts. A few years ago, I inherited a few dozen ancient CGI scripts (Perl and otherwise) that required Immediate Attention. CGI led to Perl, and to Apache ^[?] ; Perl and Apache led, naturally enough, to mod_perl ^[?] , once I started hitting the performance bottlenecks inherenent in CGI programming. After researching mod_perl, building a mod_perl-enalbed Apache, and reading all the available online documentation, I got it up and running--and I was suitably impressed.

So, when O'Reilly ^[?] announced a book devoted to programming Apache with Perl, I was extremely excited. The book starts with an introduction and history of web programming, introduces CGI and other types of web programming (server API ^[?] 's, such as ISAPI and NSAPI; embedded processors, such as mod_perl, mod_dtcl, and mod_pyapache; FastCGI; Java ^[?] servlets ^[?] ; ActiveX ^[?] ; and client-side scripting languages, such as VBScript ^[?] and JavaScript ^[?] ), and then describes the Apache module architecture, using some simple examples ("Hello, World" in Perl and in C). Then it gets good, covering dynamically generated content; the hobgoblin of HTTP, state; and all the other stuff that gives CGI programmer nightmares (like authentication and authorization).

What's Bad?

Although the title reads '... with Perl and C', the emphasis is very obviously on Perl. The C API reference chapters (chapters 10 and 11, pages 505 through 631) are very thorough, but almost all the examples are in Perl only. In fact, the authors go so far as to recommend that almost all Apache modules be written in Perl, and not C, except for very small modules or modules that need that extra speed boost or small memory footprint of being compiled into the server (page 13: "Anything you can do with the C API you can do with mod_perl with less fuss and bother."). Their reasoning is sound: mod_perl modules and scripts require a server restart at most, and often not even that, while for C modules, Apache itself must be recompiled; but I was expecting more in this area, perhaps a larger section on using DSO. After the book was published, however, several of the Perl-only examples were ported to the C API, and are available for download.

A few of these examples have already been published, and in these cases the book is mostly redundant. Notably, the Apache::NavBar module (which Lincoln uses on the server in his lab) and the Apache::AdBlocker module (chapters 4 and 7), appeared in The Perl Journal last year (issues 12 and 11). This is not that big a deal, since both of these modules are incredibly useful and probably deserve to be published in a few more places, but two brand new modules would have been most welcome, especially since the book's target audience probably also reads The Perl Journal.

What's Good?

There's a lot to like here. Since I'm a Perl programmer by trade and disposition, I personally liked the fact that 99.9% of the examples were written in Perl. With only a few exceptions, the modules could be copied into the right locations and run immediately; the exceptions were the modules that made use of either other programs (Chapter 5's Hangman program which uses a relational database to store state information) or specialized Apache features (Chapter 7's Apache::AdBlocker module, which requires proxy functionality).

Much of the text and all of the source code is available on the web at www.modperl.com. Chapters 6, 7, 8, and 9 can be found on the web site for the book, as can all the Perl modules and some of the examples in functional form (Apache::Magic and hangman).

Chapter 9 is the key chapter, and the heart of the book. It describes in great detail all the Apache:: modules. If you use mod_perl at all, download and print this chapter. Memorize it. Use your favorite indexing script to make it searchable. Everything you need to know about mod_perl is here in this chapter.

The appendices are also excellent, although, because it is an Apache book, I would have figured that several of the sections would be regular chapters, and not relegated to the end. The appendices are divided pretty evenly between concentrating on Perl and on C, unlike most of the rest of the book.

So What's In It For Me?

Fortunately for people like me, there is a lot of information about mod_perl on the web; The Perl Journal has had several articles on it, WebMonkey has had an article or two, and so on. There is a comprehensive mod_perl developer's guide on the offical Apache/Perl site. Lincoln Stein uses it a lot on his site and in his software. And, of course, we have the man pages and perldocs. So why do we need a book?

A few reasons. First and foremost, few of those sources go into the kind of detail that this book does, while still being approachable. Second, the book focuses on Apache, programming Apache, and (to a lesser extent) programming applications on the web; Perl and C are the means here, not the end. The in-depth technical discussions are about Apache: how it translates URI's to filenames, how it handles subrequests and internal redirects, how it maps files to MIME types. It then presents techniques for usurping these functions, customizing each phase of the reponse process, and explains when and why you would want to do this, instead of letting Apache do it's own thing. Creating checksums on the fly, compressing and decompressing data, creating extremely flexible HTML preprocessors, and modifying outgoing and incoming headers are some just some of the given examples.

The reference chapters are probably the single most valuable thing about the book. If you are a Perl programmer on a budget, you can download chapter 9 from the web site, but the C programmers out there have to buy the book to get the C API refernce. The C reference is 2 chapters (126 pages) long, and covers all the functions in precise detail.

For those among you who are using Microsoft operating systems, the book pays special attention to building, installing, and configuring mod_perl and Apache on Win32 systems, where it is different from Unix and Unix-like systems. Most of the actual modules are very similar (except for the obvious ones, such as scripts that call sendmail and the scripts that access MySQL), but the installation and building of mod_perl (or ApacheModulePerl.dll) are very different. The process is described in enough detail to make it possible, without boring those readers to whom it is irrelevant.

Conclusion

Programming Apache/mod_perl without this book is like writing Perl without the camel book. It can be done, but it is much easier and more enjoyable with the book. The writing is clear, informative, straight-forward, and, at times, amusing. The authors are the definitive sources for information on mod_perl and CGI programming, and this is reflected in every aspect of the book. While not as definitive for C programmers, it is still the best Apache API reference out there, other than the actual source code itself.

Purchase this book at Amazon.

Errata Table of Contents

1. Server-Side Programming with Apache
2. A First Module
3. The Apache Module Architecture and API
4. Content Handlers
5. Maintaining State
6. Authentication and Authorization
7. Other Request Phases
8. Customizing the Apache Configuration Process
9. Perl API Reference Guide
10. C API Reference Guide, Part I
11. API Reference Guide, Part II

1. Standard Noncore Modules
2. Building and Installing mod_perl
3. Building Multifile C API Modules
4. Apache:: Modules Available on CPAN
5. Third-Party C Modules
6. HTML::Embperl--Embedding Perl Code in HTML

Thanks to darrn chamberlain for an excellent review of the Lincoln Stein and Doug MacEachern book Writing Apache Modules with Perl and C. This is an excellent book for those considering working with Apache and mod_perl, and helpful for C programmers. Click below for more details. Writing Apache Modules with Perl and C author Li pages 724 publisher O'Reilly, ISBN: 156592567X rating 9.5/10 reviewer darren chamberlain ISBN summary Absolutely essential for anyone who is considering using Apache and mod_perl. C programmers may need more. The Scenario

If you're like me, your first introduction to Perl ^[?] was in the form of CGI ^[?] scripts. A few years ago, I inherited a few dozen ancient CGI scripts (Perl and otherwise) that required Immediate Attention. CGI led to Perl, and to Apache ^[?] ; Perl and Apache led, naturally enough, to mod_perl ^[?] , once I started hitting the performance bottlenecks inherenent in CGI programming. After researching mod_perl, building a mod_perl-enalbed Apache, and reading all the available online documentation, I got it up and running--and I was suitably impressed.

So, when O'Reilly ^[?] announced a book devoted to programming Apache with Perl, I was extremely excited. The book starts with an introduction and history of web programming, introduces CGI and other types of web programming (server API ^[?] 's, such as ISAPI and NSAPI; embedded processors, such as mod_perl, mod_dtcl, and mod_pyapache; FastCGI; Java ^[?] servlets ^[?] ; ActiveX ^[?] ; and client-side scripting languages, such as VBScript ^[?] and JavaScript ^[?] ), and then describes the Apache module architecture, using some simple examples ("Hello, World" in Perl and in C). Then it gets good, covering dynamically generated content; the hobgoblin of HTTP, state; and all the other stuff that gives CGI programmer nightmares (like authentication and authorization).

What's Bad?

Although the title reads '... with Perl and C', the emphasis is very obviously on Perl. The C API reference chapters (chapters 10 and 11, pages 505 through 631) are very thorough, but almost all the examples are in Perl only. In fact, the authors go so far as to recommend that almost all Apache modules be written in Perl, and not C, except for very small modules or modules that need that extra speed boost or small memory footprint of being compiled into the server (page 13: "Anything you can do with the C API you can do with mod_perl with less fuss and bother."). Their reasoning is sound: mod_perl modules and scripts require a server restart at most, and often not even that, while for C modules, Apache itself must be recompiled; but I was expecting more in this area, perhaps a larger section on using DSO. After the book was published, however, several of the Perl-only examples were ported to the C API, and are available for download.

A few of these examples have already been published, and in these cases the book is mostly redundant. Notably, the Apache::NavBar module (which Lincoln uses on the server in his lab) and the Apache::AdBlocker module (chapters 4 and 7), appeared in The Perl Journal last year (issues 12 and 11). This is not that big a deal, since both of these modules are incredibly useful and probably deserve to be published in a few more places, but two brand new modules would have been most welcome, especially since the book's target audience probably also reads The Perl Journal.

What's Good?

There's a lot to like here. Since I'm a Perl programmer by trade and disposition, I personally liked the fact that 99.9% of the examples were written in Perl. With only a few exceptions, the modules could be copied into the right locations and run immediately; the exceptions were the modules that made use of either other programs (Chapter 5's Hangman program which uses a relational database to store state information) or specialized Apache features (Chapter 7's Apache::AdBlocker module, which requires proxy functionality).

Much of the text and all of the source code is available on the web at www.modperl.com. Chapters 6, 7, 8, and 9 can be found on the web site for the book, as can all the Perl modules and some of the examples in functional form (Apache::Magic and hangman).

Chapter 9 is the key chapter, and the heart of the book. It describes in great detail all the Apache:: modules. If you use mod_perl at all, download and print this chapter. Memorize it. Use your favorite indexing script to make it searchable. Everything you need to know about mod_perl is here in this chapter.

The appendices are also excellent, although, because it is an Apache book, I would have figured that several of the sections would be regular chapters, and not relegated to the end. The appendices are divided pretty evenly between concentrating on Perl and on C, unlike most of the rest of the book.

So What's In It For Me?

Fortunately for people like me, there is a lot of information about mod_perl on the web; The Perl Journal has had several articles on it, WebMonkey has had an article or two, and so on. There is a comprehensive mod_perl developer's guide on the offical Apache/Perl site. Lincoln Stein uses it a lot on his site and in his software. And, of course, we have the man pages and perldocs. So why do we need a book?

A few reasons. First and foremost, few of those sources go into the kind of detail that this book does, while still being approachable. Second, the book focuses on Apache, programming Apache, and (to a lesser extent) programming applications on the web; Perl and C are the means here, not the end. The in-depth technical discussions are about Apache: how it translates URI's to filenames, how it handles subrequests and internal redirects, how it maps files to MIME types. It then presents techniques for usurping these functions, customizing each phase of the reponse process, and explains when and why you would want to do this, instead of letting Apache do it's own thing. Creating checksums on the fly, compressing and decompressing data, creating extremely flexible HTML preprocessors, and modifying outgoing and incoming headers are some just some of the given examples.

The reference chapters are probably the single most valuable thing about the book. If you are a Perl programmer on a budget, you can download chapter 9 from the web site, but the C programmers out there have to buy the book to get the C API refernce. The C reference is 2 chapters (126 pages) long, and covers all the functions in precise detail.

For those among you who are using Microsoft operating systems, the book pays special attention to building, installing, and configuring mod_perl and Apache on Win32 systems, where it is different from Unix and Unix-like systems. Most of the actual modules are very similar (except for the obvious ones, such as scripts that call sendmail and the scripts that access MySQL), but the installation and building of mod_perl (or ApacheModulePerl.dll) are very different. The process is described in enough detail to make it possible, without boring those readers to whom it is irrelevant.

Conclusion

Programming Apache/mod_perl without this book is like writing Perl without the camel book. It can be done, but it is much easier and more enjoyable with the book. The writing is clear, informative, straight-forward, and, at times, amusing. The authors are the definitive sources for information on mod_perl and CGI programming, and this is reflected in every aspect of the book. While not as definitive for C programmers, it is still the best Apache API reference out there, other than the actual source code itself.

Purchase this book at Amazon.

Errata Table of Contents

1. Server-Side Programming with Apache
2. A First Module
3. The Apache Module Architecture and API
4. Content Handlers
5. Maintaining State
6. Authentication and Authorization
7. Other Request Phases
8. Customizing the Apache Configuration Process
9. Perl API Reference Guide
10. C API Reference Guide, Part I
11. API Reference Guide, Part II

1. Standard Noncore Modules
2. Building and Installing mod_perl
3. Building Multifile C API Modules
4. Apache:: Modules Available on CPAN
5. Third-Party C Modules
6. HTML::Embperl--Embedding Perl Code in HTML

Thanks to darrn chamberlain for an excellent review of the Lincoln Stein and Doug MacEachern book Writing Apache Modules with Perl and C. This is an excellent book for those considering working with Apache and mod_perl, and helpful for C programmers. Click below for more details. Writing Apache Modules with Perl and C author Li pages 724 publisher O'Reilly, ISBN: 156592567X rating 9.5/10 reviewer darren chamberlain ISBN summary Absolutely essential for anyone who is considering using Apache and mod_perl. C programmers may need more. The Scenario

If you're like me, your first introduction to Perl ^[?] was in the form of CGI ^[?] scripts. A few years ago, I inherited a few dozen ancient CGI scripts (Perl and otherwise) that required Immediate Attention. CGI led to Perl, and to Apache ^[?] ; Perl and Apache led, naturally enough, to mod_perl ^[?] , once I started hitting the performance bottlenecks inherenent in CGI programming. After researching mod_perl, building a mod_perl-enalbed Apache, and reading all the available online documentation, I got it up and running--and I was suitably impressed.

So, when O'Reilly ^[?] announced a book devoted to programming Apache with Perl, I was extremely excited. The book starts with an introduction and history of web programming, introduces CGI and other types of web programming (server API ^[?] 's, such as ISAPI and NSAPI; embedded processors, such as mod_perl, mod_dtcl, and mod_pyapache; FastCGI; Java ^[?] servlets ^[?] ; ActiveX ^[?] ; and client-side scripting languages, such as VBScript ^[?] and JavaScript ^[?] ), and then describes the Apache module architecture, using some simple examples ("Hello, World" in Perl and in C). Then it gets good, covering dynamically generated content; the hobgoblin of HTTP, state; and all the other stuff that gives CGI programmer nightmares (like authentication and authorization).

What's Bad?

Although the title reads '... with Perl and C', the emphasis is very obviously on Perl. The C API reference chapters (chapters 10 and 11, pages 505 through 631) are very thorough, but almost all the examples are in Perl only. In fact, the authors go so far as to recommend that almost all Apache modules be written in Perl, and not C, except for very small modules or modules that need that extra speed boost or small memory footprint of being compiled into the server (page 13: "Anything you can do with the C API you can do with mod_perl with less fuss and bother."). Their reasoning is sound: mod_perl modules and scripts require a server restart at most, and often not even that, while for C modules, Apache itself must be recompiled; but I was expecting more in this area, perhaps a larger section on using DSO. After the book was published, however, several of the Perl-only examples were ported to the C API, and are available for download.

A few of these examples have already been published, and in these cases the book is mostly redundant. Notably, the Apache::NavBar module (which Lincoln uses on the server in his lab) and the Apache::AdBlocker module (chapters 4 and 7), appeared in The Perl Journal last year (issues 12 and 11). This is not that big a deal, since both of these modules are incredibly useful and probably deserve to be published in a few more places, but two brand new modules would have been most welcome, especially since the book's target audience probably also reads The Perl Journal.

What's Good?

There's a lot to like here. Since I'm a Perl programmer by trade and disposition, I personally liked the fact that 99.9% of the examples were written in Perl. With only a few exceptions, the modules could be copied into the right locations and run immediately; the exceptions were the modules that made use of either other programs (Chapter 5's Hangman program which uses a relational database to store state information) or specialized Apache features (Chapter 7's Apache::AdBlocker module, which requires proxy functionality).

Much of the text and all of the source code is available on the web at www.modperl.com. Chapters 6, 7, 8, and 9 can be found on the web site for the book, as can all the Perl modules and some of the examples in functional form (Apache::Magic and hangman).

Chapter 9 is the key chapter, and the heart of the book. It describes in great detail all the Apache:: modules. If you use mod_perl at all, download and print this chapter. Memorize it. Use your favorite indexing script to make it searchable. Everything you need to know about mod_perl is here in this chapter.

The appendices are also excellent, although, because it is an Apache book, I would have figured that several of the sections would be regular chapters, and not relegated to the end. The appendices are divided pretty evenly between concentrating on Perl and on C, unlike most of the rest of the book.

So What's In It For Me?

Fortunately for people like me, there is a lot of information about mod_perl on the web; The Perl Journal has had several articles on it, WebMonkey has had an article or two, and so on. There is a comprehensive mod_perl developer's guide on the offical Apache/Perl site. Lincoln Stein uses it a lot on his site and in his software. And, of course, we have the man pages and perldocs. So why do we need a book?

A few reasons. First and foremost, few of those sources go into the kind of detail that this book does, while still being approachable. Second, the book focuses on Apache, programming Apache, and (to a lesser extent) programming applications on the web; Perl and C are the means here, not the end. The in-depth technical discussions are about Apache: how it translates URI's to filenames, how it handles subrequests and internal redirects, how it maps files to MIME types. It then presents techniques for usurping these functions, customizing each phase of the reponse process, and explains when and why you would want to do this, instead of letting Apache do it's own thing. Creating checksums on the fly, compressing and decompressing data, creating extremely flexible HTML preprocessors, and modifying outgoing and incoming headers are some just some of the given examples.

The reference chapters are probably the single most valuable thing about the book. If you are a Perl programmer on a budget, you can download chapter 9 from the web site, but the C programmers out there have to buy the book to get the C API refernce. The C reference is 2 chapters (126 pages) long, and covers all the functions in precise detail.

For those among you who are using Microsoft operating systems, the book pays special attention to building, installing, and configuring mod_perl and Apache on Win32 systems, where it is different from Unix and Unix-like systems. Most of the actual modules are very similar (except for the obvious ones, such as scripts that call sendmail and the scripts that access MySQL), but the installation and building of mod_perl (or ApacheModulePerl.dll) are very different. The process is described in enough detail to make it possible, without boring those readers to whom it is irrelevant.

Conclusion

Programming Apache/mod_perl without this book is like writing Perl without the camel book. It can be done, but it is much easier and more enjoyable with the book. The writing is clear, informative, straight-forward, and, at times, amusing. The authors are the definitive sources for information on mod_perl and CGI programming, and this is reflected in every aspect of the book. While not as definitive for C programmers, it is still the best Apache API reference out there, other than the actual source code itself.

Purchase this book at Amazon.

Errata Table of Contents

1. Server-Side Programming with Apache
2. A First Module
3. The Apache Module Architecture and API
4. Content Handlers
5. Maintaining State
6. Authentication and Authorization
7. Other Request Phases
8. Customizing the Apache Configuration Process
9. Perl API Reference Guide
10. C API Reference Guide, Part I
11. API Reference Guide, Part II

1. Standard Noncore Modules
2. Building and Installing mod_perl
3. Building Multifile C API Modules
4. Apache:: Modules Available on CPAN
5. Third-Party C Modules
6. HTML::Embperl--Embedding Perl Code in HTML

Thanks to darrn chamberlain for an excellent review of the Lincoln Stein and Doug MacEachern book Writing Apache Modules with Perl and C. This is an excellent book for those considering working with Apache and mod_perl, and helpful for C programmers. Click below for more details. Writing Apache Modules with Perl and C author Li pages 724 publisher O'Reilly, ISBN: 156592567X rating 9.5/10 reviewer darren chamberlain ISBN summary Absolutely essential for anyone who is considering using Apache and mod_perl. C programmers may need more. The Scenario

If you're like me, your first introduction to Perl ^[?] was in the form of CGI ^[?] scripts. A few years ago, I inherited a few dozen ancient CGI scripts (Perl and otherwise) that required Immediate Attention. CGI led to Perl, and to Apache ^[?] ; Perl and Apache led, naturally enough, to mod_perl ^[?] , once I started hitting the performance bottlenecks inherenent in CGI programming. After researching mod_perl, building a mod_perl-enalbed Apache, and reading all the available online documentation, I got it up and running--and I was suitably impressed.

So, when O'Reilly ^[?] announced a book devoted to programming Apache with Perl, I was extremely excited. The book starts with an introduction and history of web programming, introduces CGI and other types of web programming (server API ^[?] 's, such as ISAPI and NSAPI; embedded processors, such as mod_perl, mod_dtcl, and mod_pyapache; FastCGI; Java ^[?] servlets ^[?] ; ActiveX ^[?] ; and client-side scripting languages, such as VBScript ^[?] and JavaScript ^[?] ), and then describes the Apache module architecture, using some simple examples ("Hello, World" in Perl and in C). Then it gets good, covering dynamically generated content; the hobgoblin of HTTP, state; and all the other stuff that gives CGI programmer nightmares (like authentication and authorization).

What's Bad?

Although the title reads '... with Perl and C', the emphasis is very obviously on Perl. The C API reference chapters (chapters 10 and 11, pages 505 through 631) are very thorough, but almost all the examples are in Perl only. In fact, the authors go so far as to recommend that almost all Apache modules be written in Perl, and not C, except for very small modules or modules that need that extra speed boost or small memory footprint of being compiled into the server (page 13: "Anything you can do with the C API you can do with mod_perl with less fuss and bother."). Their reasoning is sound: mod_perl modules and scripts require a server restart at most, and often not even that, while for C modules, Apache itself must be recompiled; but I was expecting more in this area, perhaps a larger section on using DSO. After the book was published, however, several of the Perl-only examples were ported to the C API, and are available for download.

A few of these examples have already been published, and in these cases the book is mostly redundant. Notably, the Apache::NavBar module (which Lincoln uses on the server in his lab) and the Apache::AdBlocker module (chapters 4 and 7), appeared in The Perl Journal last year (issues 12 and 11). This is not that big a deal, since both of these modules are incredibly useful and probably deserve to be published in a few more places, but two brand new modules would have been most welcome, especially since the book's target audience probably also reads The Perl Journal.

What's Good?

There's a lot to like here. Since I'm a Perl programmer by trade and disposition, I personally liked the fact that 99.9% of the examples were written in Perl. With only a few exceptions, the modules could be copied into the right locations and run immediately; the exceptions were the modules that made use of either other programs (Chapter 5's Hangman program which uses a relational database to store state information) or specialized Apache features (Chapter 7's Apache::AdBlocker module, which requires proxy functionality).

Much of the text and all of the source code is available on the web at www.modperl.com. Chapters 6, 7, 8, and 9 can be found on the web site for the book, as can all the Perl modules and some of the examples in functional form (Apache::Magic and hangman).

Chapter 9 is the key chapter, and the heart of the book. It describes in great detail all the Apache:: modules. If you use mod_perl at all, download and print this chapter. Memorize it. Use your favorite indexing script to make it searchable. Everything you need to know about mod_perl is here in this chapter.

The appendices are also excellent, although, because it is an Apache book, I would have figured that several of the sections would be regular chapters, and not relegated to the end. The appendices are divided pretty evenly between concentrating on Perl and on C, unlike most of the rest of the book.

So What's In It For Me?

Fortunately for people like me, there is a lot of information about mod_perl on the web; The Perl Journal has had several articles on it, WebMonkey has had an article or two, and so on. There is a comprehensive mod_perl developer's guide on the offical Apache/Perl site. Lincoln Stein uses it a lot on his site and in his software. And, of course, we have the man pages and perldocs. So why do we need a book?

A few reasons. First and foremost, few of those sources go into the kind of detail that this book does, while still being approachable. Second, the book focuses on Apache, programming Apache, and (to a lesser extent) programming applications on the web; Perl and C are the means here, not the end. The in-depth technical discussions are about Apache: how it translates URI's to filenames, how it handles subrequests and internal redirects, how it maps files to MIME types. It then presents techniques for usurping these functions, customizing each phase of the reponse process, and explains when and why you would want to do this, instead of letting Apache do it's own thing. Creating checksums on the fly, compressing and decompressing data, creating extremely flexible HTML preprocessors, and modifying outgoing and incoming headers are some just some of the given examples.

The reference chapters are probably the single most valuable thing about the book. If you are a Perl programmer on a budget, you can download chapter 9 from the web site, but the C programmers out there have to buy the book to get the C API refernce. The C reference is 2 chapters (126 pages) long, and covers all the functions in precise detail.

For those among you who are using Microsoft operating systems, the book pays special attention to building, installing, and configuring mod_perl and Apache on Win32 systems, where it is different from Unix and Unix-like systems. Most of the actual modules are very similar (except for the obvious ones, such as scripts that call sendmail and the scripts that access MySQL), but the installation and building of mod_perl (or ApacheModulePerl.dll) are very different. The process is described in enough detail to make it possible, without boring those readers to whom it is irrelevant.

Conclusion

Programming Apache/mod_perl without this book is like writing Perl without the camel book. It can be done, but it is much easier and more enjoyable with the book. The writing is clear, informative, straight-forward, and, at times, amusing. The authors are the definitive sources for information on mod_perl and CGI programming, and this is reflected in every aspect of the book. While not as definitive for C programmers, it is still the best Apache API reference out there, other than the actual source code itself.

Purchase this book at Amazon.

Errata Table of Contents

1. Server-Side Programming with Apache
2. A First Module
3. The Apache Module Architecture and API
4. Content Handlers
5. Maintaining State
6. Authentication and Authorization
7. Other Request Phases
8. Customizing the Apache Configuration Process
9. Perl API Reference Guide
10. C API Reference Guide, Part I
11. API Reference Guide, Part II

1. Standard Noncore Modules
2. Building and Installing mod_perl
3. Building Multifile C API Modules
4. Apache:: Modules Available on CPAN
5. Third-Party C Modules
6. HTML::Embperl--Embedding Perl Code in HTML

Thanks to darrn chamberlain for an excellent review of the Lincoln Stein and Doug MacEachern book Writing Apache Modules with Perl and C. This is an excellent book for those considering working with Apache and mod_perl, and helpful for C programmers. Click below for more details. Writing Apache Modules with Perl and C author Li pages 724 publisher O'Reilly, ISBN: 156592567X rating 9.5/10 reviewer darren chamberlain ISBN summary Absolutely essential for anyone who is considering using Apache and mod_perl. C programmers may need more. The Scenario

If you're like me, your first introduction to Perl ^[?] was in the form of CGI ^[?] scripts. A few years ago, I inherited a few dozen ancient CGI scripts (Perl and otherwise) that required Immediate Attention. CGI led to Perl, and to Apache ^[?] ; Perl and Apache led, naturally enough, to mod_perl ^[?] , once I started hitting the performance bottlenecks inherenent in CGI programming. After researching mod_perl, building a mod_perl-enalbed Apache, and reading all the available online documentation, I got it up and running--and I was suitably impressed.

So, when O'Reilly ^[?] announced a book devoted to programming Apache with Perl, I was extremely excited. The book starts with an introduction and history of web programming, introduces CGI and other types of web programming (server API ^[?] 's, such as ISAPI and NSAPI; embedded processors, such as mod_perl, mod_dtcl, and mod_pyapache; FastCGI; Java ^[?] servlets ^[?] ; ActiveX ^[?] ; and client-side scripting languages, such as VBScript ^[?] and JavaScript ^[?] ), and then describes the Apache module architecture, using some simple examples ("Hello, World" in Perl and in C). Then it gets good, covering dynamically generated content; the hobgoblin of HTTP, state; and all the other stuff that gives CGI programmer nightmares (like authentication and authorization).

What's Bad?

Although the title reads '... with Perl and C', the emphasis is very obviously on Perl. The C API reference chapters (chapters 10 and 11, pages 505 through 631) are very thorough, but almost all the examples are in Perl only. In fact, the authors go so far as to recommend that almost all Apache modules be written in Perl, and not C, except for very small modules or modules that need that extra speed boost or small memory footprint of being compiled into the server (page 13: "Anything you can do with the C API you can do with mod_perl with less fuss and bother."). Their reasoning is sound: mod_perl modules and scripts require a server restart at most, and often not even that, while for C modules, Apache itself must be recompiled; but I was expecting more in this area, perhaps a larger section on using DSO. After the book was published, however, several of the Perl-only examples were ported to the C API, and are available for download.

A few of these examples have already been published, and in these cases the book is mostly redundant. Notably, the Apache::NavBar module (which Lincoln uses on the server in his lab) and the Apache::AdBlocker module (chapters 4 and 7), appeared in The Perl Journal last year (issues 12 and 11). This is not that big a deal, since both of these modules are incredibly useful and probably deserve to be published in a few more places, but two brand new modules would have been most welcome, especially since the book's target audience probably also reads The Perl Journal.

What's Good?

There's a lot to like here. Since I'm a Perl programmer by trade and disposition, I personally liked the fact that 99.9% of the examples were written in Perl. With only a few exceptions, the modules could be copied into the right locations and run immediately; the exceptions were the modules that made use of either other programs (Chapter 5's Hangman program which uses a relational database to store state information) or specialized Apache features (Chapter 7's Apache::AdBlocker module, which requires proxy functionality).

Much of the text and all of the source code is available on the web at www.modperl.com. Chapters 6, 7, 8, and 9 can be found on the web site for the book, as can all the Perl modules and some of the examples in functional form (Apache::Magic and hangman).

Chapter 9 is the key chapter, and the heart of the book. It describes in great detail all the Apache:: modules. If you use mod_perl at all, download and print this chapter. Memorize it. Use your favorite indexing script to make it searchable. Everything you need to know about mod_perl is here in this chapter.

The appendices are also excellent, although, because it is an Apache book, I would have figured that several of the sections would be regular chapters, and not relegated to the end. The appendices are divided pretty evenly between concentrating on Perl and on C, unlike most of the rest of the book.

So What's In It For Me?

Fortunately for people like me, there is a lot of information about mod_perl on the web; The Perl Journal has had several articles on it, WebMonkey has had an article or two, and so on. There is a comprehensive mod_perl developer's guide on the offical Apache/Perl site. Lincoln Stein uses it a lot on his site and in his software. And, of course, we have the man pages and perldocs. So why do we need a book?

A few reasons. First and foremost, few of those sources go into the kind of detail that this book does, while still being approachable. Second, the book focuses on Apache, programming Apache, and (to a lesser extent) programming applications on the web; Perl and C are the means here, not the end. The in-depth technical discussions are about Apache: how it translates URI's to filenames, how it handles subrequests and internal redirects, how it maps files to MIME types. It then presents techniques for usurping these functions, customizing each phase of the reponse process, and explains when and why you would want to do this, instead of letting Apache do it's own thing. Creating checksums on the fly, compressing and decompressing data, creating extremely flexible HTML preprocessors, and modifying outgoing and incoming headers are some just some of the given examples.

The reference chapters are probably the single most valuable thing about the book. If you are a Perl programmer on a budget, you can download chapter 9 from the web site, but the C programmers out there have to buy the book to get the C API refernce. The C reference is 2 chapters (126 pages) long, and covers all the functions in precise detail.

For those among you who are using Microsoft operating systems, the book pays special attention to building, installing, and configuring mod_perl and Apache on Win32 systems, where it is different from Unix and Unix-like systems. Most of the actual modules are very similar (except for the obvious ones, such as scripts that call sendmail and the scripts that access MySQL), but the installation and building of mod_perl (or ApacheModulePerl.dll) are very different. The process is described in enough detail to make it possible, without boring those readers to whom it is irrelevant.

Conclusion

Programming Apache/mod_perl without this book is like writing Perl without the camel book. It can be done, but it is much easier and more enjoyable with the book. The writing is clear, informative, straight-forward, and, at times, amusing. The authors are the definitive sources for information on mod_perl and CGI programming, and this is reflected in every aspect of the book. While not as definitive for C programmers, it is still the best Apache API reference out there, other than the actual source code itself.

Purchase this book at Amazon.

Errata Table of Contents

1. Server-Side Programming with Apache
2. A First Module
3. The Apache Module Architecture and API
4. Content Handlers
5. Maintaining State
6. Authentication and Authorization
7. Other Request Phases
8. Customizing the Apache Configuration Process
9. Perl API Reference Guide
10. C API Reference Guide, Part I
11. API Reference Guide, Part II

1. Standard Noncore Modules
2. Building and Installing mod_perl
3. Building Multifile C API Modules
4. Apache:: Modules Available on CPAN
5. Third-Party C Modules
6. HTML::Embperl--Embedding Perl Code in HTML