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How Tomcat Works
First of all, this is the only book I know of that explains how the complete system works. You can find good documentation on how to use this most popular servlet container on the Tomcat project's Web site, but little is said about how it works. If you want to join this open source project, good luck. You should consider yourself lucky (or very brilliant) if you can understand how the system works in less than 3 months by browsing through its millions of lines of code.
However, why I find this book appealing is because of the approach the authors take in analyzing it: build Tomcat from scratch, line of code by line of code, module by module. Miraculously, in doing so they never fail to make sure their readers can follow the technical discussions. In their hands, Tomcat looks easy that even beginners of Java can understand. There are many complex technologies used in Tomcat, and they are all explained well.
The book starts off by building a dummy Web server that can do no more than sending a static HTML page. The web server is simple and consists of only three classes. The backbone of this application is the java.net.Socket class, and the authors take their time explaining this class at the beginning of the chapter. Basically, this is how the application in this chapter works: for each HTTP request, open a socket connection to the client, read the content of the static file, and send the file to the browser. As simple as that.
Chapter 2 builds on the application in Chapter 1. In this chapter, the web server gets some intelligence. It is now able to invoke a basic servlet by calling the servlet's service method. However, more complex servlets are beyond this simple servlet container, mainly because the container passes a null ServletRequest and a null ServletResponse objects to the service method. Before the authors start coding, they explain the javax.servlet package in general so that those new to servlet programming can understand this chapter.
Chapter 3 explains how to create ServletRequest and ServletResponse objects so that the servlet container in Chapter 2 can do more. The excitement comes in Chapter 4 when the authors explain how to pool ServletRequest and ServletResponse objects to beef up performance. This topic is not only relevant to Tomcat, but also Java programming in general. Object instantiation is expensive, and one way to avoid it is by reusing objects. However, you must be careful when your application will be used by many clients, as you must then think about thread safety. Chapter 4 elegantly explains how Tomcat developers solve this problem, as well as teach you a general solution for object pooling. Interestingly, a servlet is always represented by a single instance, and the same instance services all incoming requests.
The authors are also patient in explaining everything step by step, until the last chapters where they tackle more difficult problems such as Digester, JMX, class loaders and session management.
Not only will you be good at configuring Tomcat after you are finished reading this, you will also be able to tell straight away what's going on whenever your Tomcat installation throws up some error message. In addition, if you are really serious about Tomcat, you can start thinking of writing your own modules or extending the existing ones. For example, as the authors have demonstrated, you can extend Tomcat's application loader to automatically reload a Struts application when the struts-config.xml is modified, making the application development process quicker.
This book is also great in answering many questions that seasoned servlet/JSP programmers might have long been pondering. For example, this book discusses the difference between an OutputStream and a PrintWriter, and why you can only use one of them rather than both. It also tells you why you cannot write to the request parameters or headers.
Now, as much as I liked it, this book is not perfect. The first noticeable flaw is that there are quite a number of disturbing spelling mistakes. Also, the index could have been better, not to mention a cover that is plain and uninspiring. However, I have to admit I am very happy with this book and will recommend it to any Java programmer.
You can purchase How Tomcat Works from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
Well you see, it is a male cat. And when the female cat (pussy) comes into season.... oh wait different type of tomcat. Sorry.
But I thought we weren't supposed to judge the book by it's cover?
or do java apps take up a huge amount of system resources? Everytime I launch one, my system crawls.
Look, I used to hate Java, and quite frankly I can't say I love it much yet. But to be honest, it's come a long way since the days it was unbearable. So please come off the Java bashing, it's passé. Either that or upgrade your system for crying out loud...
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
I have been paid to build MS apps for years now, but I have "watched" Java from a distance and have to say that if I started a business of my own, all applications would be written in Java/JSP. I was one of the first to attempt to build Tomcat on a Windows system and after many disasters came to love it. The inner workings of Tomcat often baffled me and now I am gonna have a book! Sadly nothing I learn will translate to my current job, but it'll be damn fun.
--I smoked my sig.
Tomcat is a Java servlet container--that is--basically a web server that serves up Java servlets, JavaServer Pages, etc.
;) open source. See more at http://jakarta.apache.org/tomcat/index.html.
It can run standalone and also serve static files such as HTML pages/graphics, etc., or it can be configured to stand behind a web server such as Apache and only handle the servlet and JSP requests that are passed to it.
Tomcat is itself written in Java and is, of course
Anyone know how this books compares to the O'Reilly book, " Tomcat: The Definitive Guide"? Also, it might be helpfull for people to know what a Servlet and JSP is before spouting out terms.
/.land using Tomcat for their production site? Also, any care to give any recomendations for an eclipse plug-in?
About the only thing common between an Applet and a Servlet is that both are writen in Java. Anyone out in
To have known how Tomcat works this past weekend when I was setting it up for a client. WHat a nightmare. Reminds me TOO MUCH of setting up Chilisoft ASP for Apache. Sure its a good idea, but I think its implemented poorly and from an administrators point of view, I found it hard to know where to start. The documentation for setting up Tomcat needs to assume that the administrator doesn't have any knowledge (or little) of Java.
nice. But, I want "How Struts Works." Debuging struts applications is one of the closest things to hell that I've experienced in some time.
Ishmael
Click on the "Tomcat project's Web site" link in the second sentence of the "rest of the review". We can't click for you. But be advised, if you have to ask these lazy questions, you probably can't program a Tomcat app, no matter what it does.
--
make install -not war
Oh yeah?
And maybe someone just wants to make money on their amazon referral?
It is available from BN for $10 less.
I passed the Turing test.
Whoa there... Java Apps (by which I presume you actually meant "Java applets", or you were trolling) have nothing to do with Tomcat, unless Tomcat itself were serving said applets.
Well, Tomcat itself is an application... written in Java... often abbreviated as a "Java App". Deploy a couple of webapps in tomcat and then check out the memory footprint of Java.exe and you'll see what he means. I've never used tomcat for production use although i do have 5.0.28 running on my workstation to test stuff, and i've found the solution to any perceived performance problems (esp. in single user mode as i do) to be RAM, RAM, and more RAM. At today's prices, why quibble: throw a gig at the problem - even if your problem isn't memory bound you'll *still* have a gig of ram! You can cackle like a maniac every time you think about it!
#!/usr/bin/english
Actually, Tomcat isn't an Apache plugin. Tomcat is a stand-alone server that can also be configured to support Apache for serving up Java web applications (which Apache cannot do on its own).
If you're a student, particularly in a technical field, you should be able to google something and learn what it is. As you progress in your technical career, you'll spend a lot of time looking up technology and solutions. It's the nature of a fluid field.
My EE profs had no patience with students who wouldn't do their own research and I've been the beneficiary of that attitude.
Learning a topic is something that should be obvious. If you are to be competitive and desirable in a tough industry - you should be used to it
Computer Science is Applied Philosophy
From this follows that object pools are counterproductive for performance (unless, of course, if resources are associated with them, like Database connections, open sockets, etc.).
I heard that quite a few app servers (including JBoss) started to refactor to get rid of object pools, but I don't have a link to back this up.
Under capitalism man exploits man. Under communism it's the other way around.
Add to that security.
I keep getting flamed by the moderators but do a search on the CIA's website for insecure langauges and software.
Php is the least secure langauge in existance and has more holes than even ASP.
I do not mean to sound trollish but its the truth and the next big wave of worms will probably be targetting at websites running php.
http://saveie6.com/
You should consider yourself lucky (or very brilliant) if you can understand how the system works in less than 3 months by browsing through its millions of lines of code.
If that's true, it sounds like it is bloated and not very well designed.
Ehrm, technically, yes. But I'll be damned if I could get the thing to be stable when I tried to set it up.
See, at my (brand spanking new) dorm, we needed a homepage. So this dude volunteers to make one, and is sent off with the words "It must work on a standard Linux/*BSD platform. No proprietary crap, please." A week later, he shows us this impressive thing running on his laptop. Only problem is, it runs under Tomcat. So I try my very best to get this thing running on our FreeBSD box, before abandoning it, and just have someone build it with PHP instead. Lessons learned working with Tomcat:
- Documentation and support is near non-existant.
- The thing is slow as molasses.
- It crashes for no reason, even while not under load.
It might very well be that I am completely incompetent, but for the most parts, I have succeeded in getting stuff up and running once I set my mind to it. But this piece of software does not exactly have my warmest recommendations.Just one mans experience. You mileage probably varies quite a bit.
I think of it this way... PHP for web applications is inevitably like building your own house from scratch... mixing the concrete, cutting down the trees, etc. All by yourself. As I've developed some web applications in PHP, this is acceptable if you're building a yurt or something.
Java servlets are what you want to use if you want to ensure some level of expandability, or at least standardized web development practices (in theory). Companies generally don't have one mega web application they run, they have anywhere from several to dozens. You don't really want to start from scratch there. Authentication? Yeah, servlets can do that. Flow control? Yeah, that's covered too. In general, if it's something you're probably going to need, the specification covers it and you can implement it based off the specification, as opposed to winging it. Or, to get back to the house thing, buying precut steel instead of making it yourself. Or, having ready-made shingles instead of copying a design that was made earlier that may be kinda shoddy even though you don't know it.
This doesn't necessarily knock down existing frameworks like Ruby on Rails, which looks pretty sweet, or anything with frameworks. Servlet containers just happen to be (more) secure, time tested foundation from which to build web applications. Tomcat is a good servlet container. We also use BEA WebLogic.
-Rob
Marriage doesn't have to suck!
You can read some sample chapters here. Just use your favorite archiving application and acrobat reader(neither included).
My boss came into my office a few minutes ago, saw this book on my desk, and asked if I had seen the review on Slashdot. I laughed a bit and said I had. I read this book many months ago, and told my boss about it.
"How Tomcat Works" is a potentially good idea, done badly.
The writing is awful. Not just inelegant, but frequently so bad that it gets in the way of the ideas being presented. Spelling, typos, grammar problems, convoluted sentences, miswordings that invert the meaning of a sentence entirely: this book has all that, and more. A fourth grade teacher with a red pen would have made this a much better book.
A book on "Tomcat Internals" is a wonderful idea; Tomcat's a somewhat complicated beast. But the approach that this book takes... it just didn't work for me. It's possible that I simply couldn't get past the bad writing. Or it may simply be that it doesn't meet my needs. I'm familiar enough with Tomcat that I don't need it explained in tiny little baby steps. What I do need, when I'm up to my ankles in Tomcat internals and trying to solve a particular problem and get on with my life, is a clean, well organized book that will quickly get me oriented, refresh my memory on the relevant bits of Tomcat's architecture, and point me to the solution to my problem. This book fails to do that.
The production values in this book leave a lot to be desired. There aren't enough diagrams, and, at least in my edition, the few that do appear are printed at very low resolution. The index is a joke. (Hint for the authors: a quick indexing script doesn't always make a useful index, okay? Second hint: hyphens denoting sequential pages are cool.)
I've learned a lot about Tomcat since reading this book... mostly by wading through the source code. After a quick initial read-through, "How Tomcat Works" has stayed on my bookshelf, untouched, for at least five or six months. This book will join "Apache Server Commentary" in the pile of books that seemed like a really good idea, but in the end, were much less helpful than I had hoped.
If you just need a book on installing or using Tomcat, or writing Java servlets in general, there are many better books. If you need a book on Tomcat internals, you probably need a better book than this one.
Remember that JSP's are simple shorthand for objects that eventually get compiled into full-fledged servlets upon their use (or earlier, if you precompile them when deploying your app). The difference between JSP's & servlets is a development-time issue only.
.NET framework. Unless you're coding your web pages in C, this "slowness" or "memory use" will be an issue, as anything else (.NET, perl, php, etc.) is all interpreted.
And there is no reason at all to mix business logic & content - in fact, application frameworks like Struts make it *hard* to do so.
The rest - slowness, memory use, etc. - could apply to any commonly used platform. I've seen studies that put certain types of java code as faster than the "managed" code of the
Or perhaps IHBT. HAND.
It is useful for not only those using Tomcat or those working with servlets/JSP/J2EE ...
As a J2EE programmer, I find the reviewer's statement to be a bit misleading.
Tomcat is not a J2EE server. The J2EE specification deals with Web Components (Servlets, JSPs) and EJBs (various EJB types and related services). Tomcat only satisfies part of the the full J2EE specification by serving Servlets and JSPs. Therefore, Tomcat is only a Web Container.
JBoss is an example of a J2EE compliant app server.