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Lucene in Action
Simon P. Chappell writes "I don't know about you, but I hardly bother with browser bookmarks any more. I used to have so many bookmarks, back in the early days of Netscape's 4 series, that I would have to regularly trim and edit my bookmark file to prevent my browser from crashing on startup -- that's a lot of bookmarks, folks! Now, I go to my favourite web search engine, enter a couple of appropriate search terms and voila, there's my page! Search engines are so ubiquitous that we rarely give much thought to the technology that powers them. Lucene in Action by Otis Gospodnetic and Erik Hatcher , both committers on the Lucene project, goes behind the HTML and takes you on a guided tour of Lucene, one of a generation of powerful Free and Open-Source search engines now available." Read on for the rest of Chappell's review.
Lucene in Action
author
Gospodnetic and Hatcher
pages
421 (7 pages of index)
publisher
Manning
rating
9
reviewer
Simon P. Chappell
ISBN
1932394281
summary
Solid introduction to Lucene
Who's it for?
Lucene is a library and framework, rather than a complete application. It truly is an engine, around which you are expected to build and extend your own application. Like Lucene, the book is targeted at those who are looking for a tool to build their own search facility application rather than just "download and go." The book does include a number of case studies of Lucene usage (including at least one download and go search engine) but those are included to show how to use and adapt Lucene to fit differing environments rather than as ends in themselves.
The Structure
The book is sensibly divided into two parts. The first part looks at "Core Lucene" functionality, while the second part addresses "Applied Lucene".
Part one has six chapters, covering the central components and inner workings of Lucene. It's here that the book starts with a tutorial introduction, familiarising the reader with the concepts of Lucene as a search engine around which you wrap your own code. The other five chapters move steadily through good search engine fare, with indexing getting the whole of chapter two to itself The discussion of how to retrieve text from the documents being indexed is mentioned here but postponed until chapter seven, where it is dealt with exhaustively. Chapter three covers searching, and especially how Lucene ranks documents.
Chapter four examines analysis. In it's chapter introduction, the book explains that "Analysis, in Lucene, is the process of converting field text into it's most fundamental indexed representation, terms." This process is performed by an analyser, which tokenises text according to it's own built in rules; each analyser will have a different emphasis, some want only dictionary words, others might explicitly include acronyms and sometimes you'll want an analyser that will block stop words (those words in languages that are part of the structure, but that add nothing to the information being conveyed by the text; classic examples of stop words in English include "a", "and" and "the").
Chapter five looks at advanced search techniques; everything from sorting search results, searching on multiple fields to filtering searches. Many free or open source software tools are extensible, and Lucene is no exception. Chapter six addresses creating and using custom components within Lucene, everything from custom sort methods to custom filters.
Part two, the final four chapters, cover Applied Lucene. It is dedicated to practical uses of Lucene and answers the question "So, what can I do with a search engine?" Chapter seven covers ways and means to parse common, non-plain text document formats. The primary formats covered are RTF, XML, PDF, HTML and Microsoft Word. The ability to parse and index these file formats will cover the search engine needs of the majority of Lucene users. Chapter eight looks at a number of Lucene tools and extensions that are available; many of them being free and open source software. Chapter nine covers ports of Lucene. While for many users, Lucene being a Java library is not a problem, some users want its functionality in environments that do not have Java. The chapter looks at ports written in C++, C#, Perl and Python. Lastly, chapter ten takes a thorough look at seven Lucene case studies. Perhaps the "star" case study is the one about Nutch, a download and go search engine written by Doug Cutting , the original author of Lucene.
There are three appendices. The first offers installation advice for Lucene; a useful addition that those newer to working with Java libraries will surely appreciate. The second appendix has a very well explained description of the Lucene index format. This is the kind of information that can be hard to find, so it is welcome in a book of this sort. The last appendix contains a number of categorised resource references. The number and breadth of the resources provided could provide quite an incredible education in information retrieval theory if the reader was inclined to read them all. What's to Like? There are several things to like about this book. Let's start with the fact that the authors are part of the core development team of Lucene. This gives them both credibility and an excellent understanding of the internal workings of Lucene. Co-author Erik Hatcher is a fantastic writer, having previously been a co-author of the only Ant book worth bothering with, Manning's Java Development with Ant . (Full disclosure: I do know Erik personally.)
The structure of the book is well thought out and each chapter does seem to move your understanding forward when combined with what you learned from the proceeding ones. The division into core and applied Lucene is also helpful. While you'd hope that this was the case, it often isn't; hence I note it as a positive.
I especially appreciate that this book does not fill up page after page with API documentation. The authors appear to have grasped that if you have Internet access to download the software, you might just be able to access the documentation online; rather, they concentrate on the way to use the software. What a concept!
As a part of Manning's "in Action" series, the book has excellent layout and has obviously been thoroughly edited by both technical evaluators and copyeditors. This might seem to be a small thing to some, but a well-edited book stands out clearly from the crowd. What's to consider? If you are looking for a book on using and configuring a download and go style of search engine, this book would be less suitable. While the case study on Nutch is of good length, it would be too short to useful as a configuration guide. Conclusion I enjoyed reading this book. If you have any text searching needs, this book will be more than sufficient equipment to guide you to successful completion. Even, if you are just looking to download a pre-written search engine, then this book will provide a good background to the nature of information retrieval in general and text indexing and searching specifically.
You can purchase Lucene in Action from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
Part one has six chapters, covering the central components and inner workings of Lucene. It's here that the book starts with a tutorial introduction, familiarising the reader with the concepts of Lucene as a search engine around which you wrap your own code. The other five chapters move steadily through good search engine fare, with indexing getting the whole of chapter two to itself The discussion of how to retrieve text from the documents being indexed is mentioned here but postponed until chapter seven, where it is dealt with exhaustively. Chapter three covers searching, and especially how Lucene ranks documents.
Chapter four examines analysis. In it's chapter introduction, the book explains that "Analysis, in Lucene, is the process of converting field text into it's most fundamental indexed representation, terms." This process is performed by an analyser, which tokenises text according to it's own built in rules; each analyser will have a different emphasis, some want only dictionary words, others might explicitly include acronyms and sometimes you'll want an analyser that will block stop words (those words in languages that are part of the structure, but that add nothing to the information being conveyed by the text; classic examples of stop words in English include "a", "and" and "the").
Chapter five looks at advanced search techniques; everything from sorting search results, searching on multiple fields to filtering searches. Many free or open source software tools are extensible, and Lucene is no exception. Chapter six addresses creating and using custom components within Lucene, everything from custom sort methods to custom filters.
Part two, the final four chapters, cover Applied Lucene. It is dedicated to practical uses of Lucene and answers the question "So, what can I do with a search engine?" Chapter seven covers ways and means to parse common, non-plain text document formats. The primary formats covered are RTF, XML, PDF, HTML and Microsoft Word. The ability to parse and index these file formats will cover the search engine needs of the majority of Lucene users. Chapter eight looks at a number of Lucene tools and extensions that are available; many of them being free and open source software. Chapter nine covers ports of Lucene. While for many users, Lucene being a Java library is not a problem, some users want its functionality in environments that do not have Java. The chapter looks at ports written in C++, C#, Perl and Python. Lastly, chapter ten takes a thorough look at seven Lucene case studies. Perhaps the "star" case study is the one about Nutch, a download and go search engine written by Doug Cutting , the original author of Lucene.
There are three appendices. The first offers installation advice for Lucene; a useful addition that those newer to working with Java libraries will surely appreciate. The second appendix has a very well explained description of the Lucene index format. This is the kind of information that can be hard to find, so it is welcome in a book of this sort. The last appendix contains a number of categorised resource references. The number and breadth of the resources provided could provide quite an incredible education in information retrieval theory if the reader was inclined to read them all. What's to Like? There are several things to like about this book. Let's start with the fact that the authors are part of the core development team of Lucene. This gives them both credibility and an excellent understanding of the internal workings of Lucene. Co-author Erik Hatcher is a fantastic writer, having previously been a co-author of the only Ant book worth bothering with, Manning's Java Development with Ant . (Full disclosure: I do know Erik personally.)
The structure of the book is well thought out and each chapter does seem to move your understanding forward when combined with what you learned from the proceeding ones. The division into core and applied Lucene is also helpful. While you'd hope that this was the case, it often isn't; hence I note it as a positive.
I especially appreciate that this book does not fill up page after page with API documentation. The authors appear to have grasped that if you have Internet access to download the software, you might just be able to access the documentation online; rather, they concentrate on the way to use the software. What a concept!
As a part of Manning's "in Action" series, the book has excellent layout and has obviously been thoroughly edited by both technical evaluators and copyeditors. This might seem to be a small thing to some, but a well-edited book stands out clearly from the crowd. What's to consider? If you are looking for a book on using and configuring a download and go style of search engine, this book would be less suitable. While the case study on Nutch is of good length, it would be too short to useful as a configuration guide. Conclusion I enjoyed reading this book. If you have any text searching needs, this book will be more than sufficient equipment to guide you to successful completion. Even, if you are just looking to download a pre-written search engine, then this book will provide a good background to the nature of information retrieval in general and text indexing and searching specifically.
You can purchase Lucene in Action from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
My home page is a nicely sorted webpage with all my frequently visited links in a password protected section of my web site. If something gets used enough in my bookmarks, it gets put on that page and gets deleted from my bookmarks. Then, no mater where I am or what computer I am on, I can access my links.
Bookmarks are more secure than a search engine, since a search engine could provide a poisoned link, and if you're typing in the URL by hand, if you make a spelling mistake, you could find yourself at a pharming site, or someplace you didn't want to go.
I tend to use bookmarks in Firefox and the autocomplete about equally, and make use of the Quick Links toolbar for my most popular sites.
The Firefox bookmark all tabs feature is a breakthrough, since you can close your browser, and reopen it to the same set of tabs as before, which is great when installing extensions and you're forced to restart. The only drawback is that scrolling through bookmarks is too slow, but if you use your scroll wheel it speeds up considerably. That's a trick I didn't figure out until just last month.
Saskboy's blog is good. 9 out of 10 dentists agree.
Does anyone find it a little funny that on the main lucene.apache.com webpage, there is a "Search this site with Google" textbox ? Kind of makes you NOT want to use their search engine if they dont' even trust it enough to work on their own site....
A million monkeys and this is the best sig they could come up with...
Typical search engines have licensing fees associated with them if you're embedding them in your application. This is basically an open source alternative. And you can customize the hell out of it. I've used it on several web-based applications and on SOA platforms, and it is fast, reliable, and easy to use. Did I mention it's open source? Take a look at the Apache site.
Some examples of customizable features are that you can index database entries and achieve quantum leaps in performance over that offered by Oracle, MySQL, PostGres, Firebird, etc. indexing. You can index formats that are not supported by the major search enginges.
It may not offer quite the performance of Google, Alta Vista, etc., but it's a FREE product, well supported by the folks at Apache, and many open source J2EE frameworks support it as well.
Lucene is not like google (it's not a full application), it's a library focused on searching text based documents (you could use it to build a mini-google).
The basic idea is that you want to build an index, and then search it, to find some document.
A document has several fields (e.g. text, title, lastModificationDate, author, categories, summary, url, etc.) which may be indexed, stored, or both.
You usually build your lucene documents, based on some real documents (e.g. web pages, PDF, records in a database, etc.), and then add them to the index.
Once you have an index, you build a query to search one or more fields (lucene provides a QueryParser class, which handles the most common cases), and you get a Hits collection containing the documents matching your query in some order (this can be customized).
Before a document is added to the index, it is passed through an Analyzer which converts the text in the fields to terms, which are the basic internal concept that is indexed.
Another interesting feature of lucene indexes is that they can be searched while they are being built without noticeable loss of search performance, and that they are process-safe (many processes can access them for reading, only one for writing), this has the drawback that the indexes are append-only (actually a separate index is created if you modify an index), but periodical optimization of the indexes removes unnecessary entries and inefficiencies.
Hope this helps!
juancn
Also, I wrote a DevX article on Lucene:
:-) Just kidding.
http://www.devx.com/Java/Article/27728/0
Lucene is so well documented and simple to use that I am surprised that this subject would fill an entire book
Lucene can be used as is, or you can extend it with your own document type handlers, etc.
As a programmer, I way prefer dynamic languages like Common Lisp, Ruby, Python, Smalltalk, etc. However, one of the things that keeps me firmly in the "Java camp" is the great free infrastructure software tools (like Lucene, Tomcat, JBoss, etc.) As a programming language, Java is kind-of weak.