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Bitter EJB 184

Posted by timothy from the mmm-bitter dept.
Michael Yuan writes "Enterprise JavaBean (EJB) is one of the most widely used technologies in enterprise Java. It is designed to be a scalable and flexible distributed framework. In EJB, almost everything can be done in several different ways and it offers the developer the maximum flexibility to choose the right approach for the project in hand." Yuan provides a review, below, of Bitter EJB, to guide programmers interested in large-scale Java development. Update: 10/27 18:27 GMT by T : Peter Wayner provides a somewhat deeper look at the book as well, also below.
Bitter EJB
author Bruce Tate, Mike Clark, Bob Lee, Patrick Linskey
pages 412
publisher Manning
rating 9
reviewer Michael Yuan, Peter Wayner
ISBN 1930110952
summary Anti-patterns in Enterprise JavaBean development

However, every coin has two sides: the other side of "freedom of choice" is "complexity". Although EJB is an incredibly powerful tool in the hands of experience architects, it is subject to a lot of misuse by novice developers who do not make sound choices. For example, some developers might use a BMP entity bean to map each database table in the system; or access entity beans directly from a distributed layer; or store large amount of data in session objects ... The list goes on. Although those approaches are technically possible, they are hardly the most efficient ways in most cases. Such problems have not only caused many projects to fail but also tarnished EJB's reputation. In fact, the complexity of EJB is often quoted as an argument for other enterprise platforms.

For EJB developers, it is crucial to learn from other people's experiences and follow proven best practices. That helps to reduce the complexity of the platform. Manning's "Bitter EJB" is a very timely book written by well-known experts in the EJB field: Bruce Tate, Mike Clark, Bob Lee and Patrick Linskey. Unlike other "architectural" books, Bitter EJB teaches best practices through common mistakes (anti-patterns). It focuses on "what not to do" but still encourages developers to come up with liberal (everything not forbidden is OK) and innovative solutions. After all, EJB is about flexibility and freedom of choices.

Part I of the book is an overview of anti-patterns in the EJB specification. The EJB specification itself has several major design problems when it first came out in March 1998. EJB v1.1 and v2.0 have gone great length to fix the anti-patterns in the specification. But early adopters may have already developed some anti-patterns in their applications. For new developers, the history also serves as a valuable lesson on what EJB is really for and how different components in the specification fall into their current places. In this part, the authors also provide an excellent recount on what went wrong in the high profile TSS Java PetStore benchmark.

Part II is about session and message-driven beans. Those beans are mainly used in the integration layers. Topics covered in this part include how to deal with large database results, whether to maintain session states, the limitations of XML and much more.

Part III covers EJB persistence. Entity EJBs are probably the most confusing types of components. Many experts have advocated to abolish entity EJBs altogether in favor of other simpler persistence frameworks such as the JDO or even simple JDBC facades. The authors discuss the pros and cons of entity EJBs and covers most leading alternatives. For those who must use entity EJBs, this book also offers useful advices on a range of topics including how to reduce round trips, shorten primary keys and handle expensive database joins etc.

Part IV covers broader topics including performance tuning, testing, building and packaging. One big problem that even EJB developer can recognize the complex deployment descriptors. One chapter of the book is dedicated to reduce code duplication, automate the deployment process and avoid the "integration hell". The last chapter of the book provides an overview of "what's next" in the EJB space.

Overall, it is an excellent book for all EJB developers and other enterprise developers who want to learn from the successes and failures of EJBs."

Peter Wayner's review:

Although there may be as many 36 plots in all of literature, the compartively new world of computer books has really had only one: this new technology is simple, very simple, and it will make your life better and your teeth whiter. Bruce Tate opened up a second plot in his book Bitter Java by exploring just how even the best programming ideas have dark sides. Now he's back with three other authors exploring the world of Bitter EJB.

This book is more fruit from the same tree. Or, to hack the Java MemeStream even more, more beans for the same mill. If you use Enterprise Java Beans (EJB), or think about using them, you should read this book to see what can go wrong. The title shows how naming schemes can be misleading because either the authors aren't really that bitter, or because they're focused entirely on EJBs. This book does not belong in the same camp with the Java==SUV crowd. These authors are really admirers who just want to warn people how to avoid problems with Java and EJB.

Tate and his new co-authors, Mike Clark, Bob Lee, and Patrick Linskey are all consultants who seem to use Java a lot, at least when they're not cheating death. One of the cuter grace notes in the book is a collection of war stories from extreme sports that are mixed in as an allegorical taste of what's to come. Before exploring the problems with a Java concept known as enterprise beans, they tell a kayaking story that ends with the sentence, "Then we hear a loud crunch and look up to see Eric's stern stationary at the top of the drop, revealing the sitaution that every kayaker dreads the most -- the vertical pin."

After stories like this, the book goes on to explore just how the very fancy enterprise beans toolkit can produce an application that moves slower than a stream filled with honey. Each chapter is filled with antipatterns, or lessons about the software learned the hard way. They're sort of like points on the map that say, "There be dragons here."

The book is divided into four parts. The first section, termed "The Basics," explores the simple ways that EJB technology goes bad. The toolkit was heavily hyped as the perfect solution for building business websites that interface seamlessly with large databases. As the business grew, new servers could be added without grief. Alas, as this section points out, there are many reasons why an elephant gun can be the wrong weapon for getting rid of mice in your house.

The next section on "Networks and Messages" describes how good ideas can turn into slow code when people misuse the fancy tools for scaling EJBs. In theory, the EJB toolkit will split up processes simply across multiple machines to handle more customers, but in practice all of the communication can slow things down considerably.
The section on "EJB Persistence" describes how the much-hyped system for seamlessly storing away enterprise beans in databases can weigh down a system. My only beef is that they left out much information on Prevayler, a much-maligned and misunderstood ultra-light toolkit that is like an anti-EJB persistence layer in every possible way. I'm enamored with it, if only because it's such a radical move away from the monolithic APIs like EJBs. While they liken using EJBs to snowboarding in fresh powder with a 100lb pack on your back, Prevayler is sort of like boots-only hiking.


The last section isn't about EJBs per se, but similar toolkits and projects that often get used with EJB. There are antipatterns to avoid with JUnitPref and Ant, too. Some of these suggestions, like some in the rest of the book, aren't terribly new or brillant, but it can't hurt to get another lecture on the importance of testing your code.

The book shines when it's exploring what goes on behind the slick facade of the API. Sure, the EJB toolkit will dutifully load up data from any object on any server in your farm, but you better be careful invoking some of these these methods because the network is slow. The book often points out how invoking that one simple method from the sales literature can start up dozens of sluggish threads. Peeling away the layers helps understand and explain why the system fails.

Many of these lessons aren't limited to Java or EJB. I wouldn't be surprised if the group of authors was busy rewriting the book with examples from .NET. Unfortunately, some programming problems are very hard, and building a toolkit with a simple API won't make them go away. In fact, the simple appearance can cause more trouble when the programmer can't understand what the secret mechanism inside is doing. Almost all of the problems in this book arise from programmers who believe the sales literature when it tells them not to pay attention to what that little bot behind the curtain is doing. If you're working in the world of EJB consulting on big iron, then you've got no choice but to start thinking about what's behind that curtain.

You can purchase the Bitter EJB from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page. Peter Wayner is the author of 13 books including Java RAMBO Manifesto and Translucent Databases.
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  • EJB is REALLY Bitter (Score:1, Interesting)

    by anandcp ( 617121 )
    I do agree with the title of the Book. EJB, especially EJB 1.1 and EJB 2.0 are def. very HUGE specifications and as hard to learn as UNIX. You have 1000's of choices which lead wayward programmers easily. Contrast this with M$FT which provides a clear Roadmap and expands complexity slowly to grasp them easier. EJB is like being pushed into the Q Continuum when you are a mere biped and not an omnipotent. It is too huge for you.
    • So, it's just like Unix compared to Windows then?

      To each their own I suppose.

      • Well no, not really. Unix can actually be taken in small steps, despite its complexity, and no knowledge of advanced uses is necessary to derive real use from the shell.

        Take grep for instance. You can start using grep right away, and do really useful work with it, without even knowing that pipes, awk and sed even exist.

        Maybe a dozen shell commands used in a fairly crude way is enough for 99.9% of users to do 99.9% of their work.

        The problem with Java in general (not just EJB) is that you really need to gr
        • The problem with Java in general (not just EJB) is that you really need to grok the whole in order to understand a simple "Hello World" program, let alone do anything really useful.

          Life is short.

          Ironically, Java was created largely to address the "life is too short" problem with C++, largely succesfully (in terms of language design). Nor have I heard many complaints about the lack of generics in Java from practicing Java programmers, as opposed to the numerous armchair quarterbacks who always seem will

          • Dude, how did we end up talking about Microsoft when I spoke only of Unix and Java? I made a criticism of Java. I did not endorse or compare to any Microsoft enviroment.

            Methinks your knee is jerking.

            For my own part, whatever it might have to do with the subject, I prefer a Linux/bash/vim/C/Python programing enviroment and avoid Windows whenever I can.

            I had decades of programing experience when I first approached Java, I found it heavy sledding to get going.

            I can't imagine how it looks to a programing no
            • Dude, how did we end up talking about Microsoft when I spoke only of Unix and Java? I made a criticism of Java. I did not endorse or compare to any Microsoft enviroment.

              Yes, I got your argument confused with some parent poster's comment. Sorry.

              I had decades of programing experience when I first approached Java, I found it heavy sledding to get going.

              All I can say about this is that it's quite likely your earlier experience wasn't heavy C++ development. Compared with that, Java is a breeze.

              There are

          • I expect Java and EJB/J2EE to have long lives ahead - at least 20 years of widespread use. Both are way ahead of C# and .Net, in almost every respect. Avoiding vendor lockin is a big priority for most IS shops these days.

            I expect Java to drop the hype in 3-5 years completely and be where Ada is now.

            I expect more hype coming to Python, especially once it gets some EJB-like "Twisted" framework. Or Erlang with its enterprise-quality EJB-like OTP framework.

            The time of dot-coms, when C{E|I|O|T}O never pla

            • How much was really written in Ada? I'd guess that Java has had more written in it, though I could be wrong. Java got spewed all over the place, so I think it'll have some staying power, although I do think it was overhyped.

              I expect more hype coming to Python, especially once it gets some EJB-like "Twisted" framework. Or Erlang with its enterprise-quality EJB-like OTP framework.

              I like the twisted [twistedmatrix.com] framework; it's practically another language on top of Python. I've recently discovered another worthy langua

            • Java is the Cobol of the next millenium. You know, '00' and onwards. Millions and millions of lines of code barfed out for businesses. Nothing lovingly handcrafted to see here.
              • I agree. The human kind will finally realize the trueth that programming is a computer science as in math based on lambda-calculus and all FP stuff like that. Java code will soon take place next to Cobol as there is no any math in OOP - it's a hype-based workaround to allow people without a good math education still to program.
          • >For me, it's very nice having most of the Unix techniques I learned in the 80's still be perfectly useful now. Two-edged sword; it can be either because the techniques are simply optimal and need no improvement or because we can't think outside the box and come up with better ones yet.
            • Two-edged sword; it can be either because the techniques are simply optimal and need no improvement or because we can't think outside the box and come up with better ones yet.

              Well, I was speaking as opposed to the forced "innovations" from Redmond that require complete re-learning every 3-5 years or so. It is nice to get things right the first time, occasionally...

              Pardon me if I wasn't clear.

              (BTW, when we do "think outside the box" and come up with better new ideas, I suspect they'll also have plenty

          • Java was created largely to address the "life is too short" problem with C++, largely succesfully (in terms of language design). Nor have I heard many complaints about the lack of generics in Java from practicing Java programmers, as opposed to the numerous armchair quarterbacks who always seem willing to share their opinion.

            The current lack of generics doesn't make Java unusable, but as a "praticing Java developer" I can tell you that Java generics (JSR 14) will sure clean up a lot of ugly code. Sure, th
        • In the EJB case, I agree that they are very complex. I've been developing EJB-based applications for several years now and one of the biggest problems for me is to explain the concept for newcomers, even if these newcomers are very good Java developers.

          Unix is complex too. I'm not talking about using the shell or the GNOME desktop. I'm referring to learning how to develop a good application. Learning C well, and learning all the Unix system calls, what they do, proper error handling, and making sure that

          • I would suggest that you have to count the time and work needed to gain experience with Python/Smalltalk as against the time it takes to understand Java then.

            An experienced programmer can pick up Python in a matter of minutes. I have not found this to be true of Java.

            KFG
            • An experienced programmer can pick up Python in a matter of minutes. I have not found this to be true of Java.
              This may be true. I have never taught Python nor SMalltalk to anyone. In fact, I can't say I know any of the languages.

              I have, however, observed over the years that the biggest hurdle for people to overcome when learning Java is to understand how to write object oriented code, and use it to your advantage.

              How long did it take for you to learn Java?

        • The problem with Java in general (not just EJB) is that you really need to grok the whole in order to understand a simple "Hello World" program

          Oh, nonsense.

          $ ls
          hello.java
          $ cat hello.java

          class hello {
          public static void main(String args[]) {
          System.out.println("Hello there!");
          }
          }

          $ gcj --main=hello hello.java
          $ ./a.out
          Hello there!
          $

          The only thing different over a gcc or g++ compile is telling it which class's "main" you want to use.

          Okay, granted, that's generating native code and not using javac

          • print "Hello World."

            I would posit that it's easier to understand this bit of code than then the one you submited.

            Sure, you and I understand your code, because we grok the whole.

            The opinion of an expert is often worthless when considering the opinion of a novice.

            As for the MFC I've had a look at it and I don't even understand the mindset that produced it in the first place.

            KFG
            • A silly argument, really. The Perl/Python/Ruby compilers wrap the same logic around your print statement that Java requires you to enter on your own. While at first, this might seem like a great advantage, it limits the ways in which the code can be used.

              Placing the hello world code in a main statement specifies a distinct context in which that code is to be used. It could just as easily be as simple as:

              System.out.println("hello world");

              Now, before you start clacking away at your keyboard, saying that al
    • very HUGE specifications and as hard to learn as UNIX. You have 1000's of choices which lead wayward programmers easily.

      Well, I learned how to cope with UNIX with the following steps:

      1. I have been tutored by a friend of mine in the basics of Unix (shell, processes, login, logout and using lynx so I was able to go on mailgate.org and see unix link there.
      2. I began using it for stupid stuff everyday, websurfing (good old lynx), writing my shit and mail (pico and pine). When I began using pico I also gave u
      • # You are not obliged to learn EJB every day in order to use them like you would do if you were pushed to work on a Sparc Workstation and you had to read your mail through mutt.

        Why are you obliged to learn again? you didn't your homework in the first place?

        Thanks to Free (Speech) Software like GNU/Linux distributions, or *BSDs, you may learn Unix as an hobby... fire up slackware, tune it and then play Wolfenstein ... EJB per se is only a mean to get a work done.

        False! after you tune your slackware yo
    • It is too huge for you.

      I agree it can seem this way at first -- especially if you don't have previous exposure to some of associated technologies or you're trying to understand the concept in a vacuum without some concrete examples to work on.

      I found "The J2EE Tutorial" (Bodoff et al, published by Adison Wesley but the content is also available on the web from Sun) very helpful by working through the simple examples.

      Sure, it's still big, but you're not expected to remember all the details any more than

    • Re:EJB is REALLY Bitter (Score:3, Informative)

      by Ryosen ( 234440 )
      Well, here I go, throwing away my mod points to respond to this flamebait....

      First, let me see if I understand your criticism correctly. Distributed architecture is a very complex and advanced form of software architecture. There is not merely one simple solution for all requirements, but an entire host of options to ensure that the right system is built to solve the problem at hand. This might include distributed components (EJB), but might also include CGI-based services (Java Servlets), asynchronous mes

      • Re:EJB is REALLY Bitter (Score:4, Insightful)

        by metamatic ( 202216 ) on Monday October 27, 2003 @04:01PM (#7321955) Homepage Journal

        One, for those who wish to develop components for use within the EJB framework, there is a small set of interfaces and objects.

        And a completely different set of deployment descriptors for every single EJB container, meaning you can't take your EAR file developed for (say) JBoss and deploy it on WebSphere or BEA. That, to me, is one of the biggest problems with EJB--zero portability of the finished packaged code. Wasn't Java supposed to be 'write once run anywhere'?

        • Yes, Java is "write once, run anywhere." The deployment descriptors are often portable provided that you do not use any of the server-specific extensions. Of course, this limits the value of investing in such servers as WebSphere and WebLogic whose value-add are those extensions. Keep in mind, however, that it is Java code that is promised to be portable, not configuration files.

          In EJB 1.0, there was no portability to speak of, as the descriptors were compiled classes. EJB 1.1 introduced a standardized XML
    • Contrast this with M$FT which provides a clear Roadmap and expands complexity slowly to grasp them easier.

      LOL! Look at the last fifteen years of Microsoft API history and make this statement again!

      Microsoft offers only the illusion of simplicity through their mind-altering marketing campaigns. Their reality is very much the opposite, where unchecked complexity and no real ways to troubleshoot problems are the main attributes of their software.

  • Where's the review? (Score:1, Insightful)

    by Anonymous Coward
    This article reads more like a summary.

  • Languages need novices, novices need good books. (Score:5, Interesting)

    by Squeebee ( 719115 ) <squeebee.gmail@com> on Monday October 27, 2003 @12:49PM (#7320127)
    "Although EJB is an incredibly powerful tool in the hands of experience architects, it is subject to a lot of misuse by novice developers who do not make sound choices."

    At least the novice developers can use it. Look at Visual Basic: VB is the most popular language with over 3 million developers simple because anyon can pick it up and get started, this leads to more developers, which leads to more apps, which helps Windows dominate the desktop.

    Now a large number of those first projects are garbage apps, but at least they give a starting point. We need languages that novices can jump into, then good books that can help steer them as they continue learning the language.

    • At least the novice developers can use it. Look at Visual Basic

      I find it funny to see your domain address.

      j/k :)

    • Re:Languages need novices, novices need good books (Score:4, Insightful)

      by kfg ( 145172 ) on Monday October 27, 2003 @01:17PM (#7320336)
      Not just for novices. I'm a "graying ponytail." I cut my teeth in real programing on an IBM 360 in APL. Selectric as the i/o device. "Changable fonts" by changing the typeball and all that.

      I'm hardly either command line nor dense mathmatical code shy.

      Today I'm a bit of a C+Python snob, but I went through a VB phase when making the switch to graphical shell programing. It was like magic. It got me up on my feet and running, producing really usable apps in the Windows enviroment in no time flat.

      I "outgrew" it in fairly short order, but as a stepping stone between "old world" and "new world" I found it invaluable.

      KFG
      • I went through that VB phase too. In those early days when OOPS was just getting more popular with C++ , I had been doing some teaching with Smalltalk as well.

        It took awhile to realize (after coding 25% of an app) that the computation model of VB was anti-OOPs.

        With the objects being forms. With data objects public and the associated fuctions private. That is the fields of a frame were public but the methods of those fields were private and not triggerable from outside pushing the buttons.

        So to make thing
    • I'll give you that tools have been lacking in the Java Enterprise world. Most of the good ones allow experienced developers be more efficient, and few really give the novice programmer a leg up.

      The biggest problem facing EJB and all of the major environments right now is not how easy it is to work in an environment, but how well the developer understands distributed components and n-tier architectures. Look at SOAP, I've worked on a couple of projects that involved SOAP, the most recent is a .NET client wr
    • That's ok, but how can you simplify distributed, parallel, scalable, fault tolerant applications with asynchronus messaging? It seems to me that the domain of the problem is complex on itself, and the tools somehow reflect this complexity.

    • Re:Languages need novices, novices need good books (Score:4, Insightful)

      by RevMike ( 632002 ) <revMike@gmail. c o m> on Monday October 27, 2003 @04:16PM (#7322083) Journal

      At least the novice developers can use it. Look at Visual Basic ... anyon[e] can pick it up and get started ... Now a large number of those first projects are garbage apps, but at least they give a starting point.

      The idea of a novice picking up J2EE is fscking hilarious. J2EE is a framework for Enterprise applications. Almost by definition, these apps are outside the purview of a novice, at least without careful hand-holding by a guru.

      Novices - using any language or environment - don't write applications with scalable components, a robust transactional system, a complex persistence mechanism, a high quality messge substrate, and a directory system.

      One might as well complain that an F-15C air superiority fighter is inferior to a Cessna 172 because a beginner can fly a Cessna with very little training. If one needs to shoot down a Mig-29, the Cessna is not going to cut it. J2EE developers need to come to the environment after deveoping a sound foundation in other technologies, up to and including RMI and CORBA.

  • Brief? (Score:2, Insightful)

    by Johnny5ive ( 719321 )
    For a review, this seems a bit short.

    A quick overview of what is contained in the book is informative, but not necessarily insightful.

    Gotta point that out; sorry for nitpicking, but I like book reviews to tell me not only what's in the book, but how good the book is.

  • Astroturfing EJB (Score:1, Insightful)

    by SunPin ( 596554 )
    Be sure to check /.'s disclaimer before reading this marketing trash...

    Principals of Slashdot and OSDN may have investments in the stocks of the companies discussed on this site and will disclose any interest if they are posting a story about those companies or their products. Contributors to this site may or may not have an interest in a company or product they are discussing. The decision to disclose that information is theirs to make. We do not guarantee the veracity, reliability or completeness of an

  • mtowtdi (Score:5, Funny)

    by Camel Pilot ( 78781 ) on Monday October 27, 2003 @12:54PM (#7320168) Homepage Journal
    From the header

    almost everything can be done in several different ways

    I guess imitation is the finest form of flattery but I think they might be violating perl's IP here.

  • Sounds Helpful (Score:3, Informative)

    by slyckshoes ( 174544 ) on Monday October 27, 2003 @12:55PM (#7320171)
    If I used EJBs, I think I would buy the book. Addressing the anti-patterns first is good, because EJBs won't save the world. But, they are very powerful in certain applications. Many posters have simply stated that EJBs are hard to develop and slow in performance. Some of these claims are true, but reasonable performance can be achieved by being smart in how you use beans, and that's what this book helps you to do.

    I'm also glad the book talks about the failed TSS PetStore performance shootout, although I'm curious about how it's presented. Suffice it to say that PetStore really isn't (or at least wasn't then) a good example of the way to do things.

    And for those complaining about the difficulty of EJBs, many AppServer vendors provide development tools that make coding EJBs very easy. Although, these tools tend to be really pricey.

  • Worth Learning? (Score:5, Insightful)

    by humandoing ( 237262 ) on Monday October 27, 2003 @12:57PM (#7320186) Homepage
    How many people have had really good experiences with EJB's? In over 3 years of doing Java development I have yet to hear anyone say anything good about developing with them.

    The vast majority of people who I have talked to seem to indicate that they have never come across any project under development where using EJB wouldn't be complete overkill, and that much simpler, easier to maintain, and cheaper solutions seem to be the path chosen.

    These aren't all small projects either, I would venture to say all of the people I have spoken with (or projects I have been working on) have been in the $50,000 - $2,000,000 range, and none of the senior developers or architects on these projects have ever dreamed of going anywhere near EJB.

    Thoughts?
    • Mod the parent up please.

      EJBs, and Java in general, are almost always entirely the WRONG approach to producing websites.

      To make an efficient site, use a scripting language like Perl [or OCaml, but I declare an interest in that], write CGIs, use mod_perl to make it run efficiently, and where you want to optimise, put your logic into stored procedures. Templating and SSIs are also useful.

      Rich.
      • Why would you want EJB to make websites? EJB is for the backoffice of the website. On the other hand there is no problem at usign servlets/jsp in a web site, is clean and have good perfomance for most cases. Using logic in store procedures is not the way to be scalable or portable, though may be faster in cases. What kind of sites do you do anyway? That can make a difference.

      • Re:Worth Learning? (Score:3, Insightful)

        by pHDNgell ( 410691 )
        EJBs, and Java in general, are almost always entirely the WRONG approach to producing websites.

        EJBs usually, java, no. The servlet architecture is one of the best things to happen to web development as far as making highly scalable web applications.

        To make an efficient site, use a scripting language like Perl [or OCaml, but I declare an interest in that], write CGIs, use mod_perl to make it run efficiently, and where you want to optimise, put your logic into stored procedures. Templating and SSIs are a
        • First, OCaml's a compiled language, not a scripting language. Scripting languages do not make a site more efficient. They might make the developer prototype more efficiently, but they aren't going to run more efficiently than something that's compiled, and in many cases, they'll provide you with surprising results later on.

          Firstly I've written mod_caml [merjis.com] which is, you'll be disappointed to know, an interface to the Apache API from Caml.

          Secondly, OCaml isn't just a compiled language.

          Thirdly, if you'd e

          • Re:Worth Learning? (Score:3, Insightful)

            by pHDNgell ( 410691 )
            Firstly I've written mod_caml which is, you'll be disappointed to know, an interface to the Apache API from Caml.

            I'm a little confused by the point of this statement. Why am I disappointed to know this?

            Secondly, OCaml isn't just a compiled language.

            Well, no, it's got a repl, but that would seem to defeat the purpose of the static typing.

            Thirdly, if you'd ever written a website you'd know that queries on the database dominate. Interpreted, compiled - it makes no difference.

            You left out the word ``
            • CGI in-process, using mod_perl or mod_caml, with database connection caching.

              (Obviously? Surely no one in 2003 would be advocating forking and connecting to the database?)

              Rich.

              • CGI in-process, using mod_perl or mod_caml, with database connection caching.

                (Obviously? Surely no one in 2003 would be advocating forking and connecting to the database?)

                Well, that's pretty much what CGI means. The CGI specification includes details like commandlines, environment variables, stdin, stdout, etc...

                When I say a well-written CGI will be slower than a well-written servlet, I'm referring to a CGI as defined in the cgi specification. mod_perl is not used for writing CGIs, it's used for mak
      • Perl CGIs don't let you separate out the website's core logic from it's presentation (HTML).

    • Re:Worth Learning? (Score:5, Interesting)

      by _xeno_ ( 155264 ) on Monday October 27, 2003 @01:39PM (#7320583) Homepage Journal
      I was going to post something like this too, but I think I'll chime in with some other questions too.

      Namely, whenever people on Slashdot complain about how EJBs are insanely slow and seem to cause more problems than they solve, someone always posts something along the lines of "they weren't used properly." Which is nice and all, but I have yet to figure out what is a proper use of EJBs. So, that's my main question - what should EJBs be used for? When are they the right tool for the job?

      I wasn't able to figure this out the last time I worked with a J2EE environment. All in all, it seemed that they were too complicated for what we were doing. And I wasn't able to see a problem where they would have been a good solution.

      Of course, I've been soured to them (or bittered, maybe?) based on the project which was basically people questioning the contractors' choice of CORBA on their Java-based system. Someone suggested to management that the contractors should have used EJBs and that this would have made the finished project "Better." So I got stuck with the task of trying to demo a system with CORBA replaced with EJBs instead - never mind the fact that most J2EE environments use CORBA as the RMI layer between beans...

      So to sum up: What is the "right way" to use EJBs? And what types of problems are they best at solving?

      • Re:Worth Learning? (Score:5, Insightful)

        by j3110 ( 193209 ) <samterrell @ g m a i l.com> on Monday October 27, 2003 @04:29PM (#7322206) Homepage
        I'm going to attempt to answer this question, but it's not really easy.

        The first thing you should think about is pre-J2EE history. Back before J2EE everyone was developing their own systems. They had their own persistance layer, their own distributed transaction system, their own network protocols in some situations. Was this system faster? Yes, of course it was. If you can develop your own system custom to your task, it's always going to be faster.

        Performance was not the reason for J2EE. Scalability was not the reason for J2EE. They are part of a new push in the software world. Overall economics is where J2EE comes in. It's more expensive to create your own framework than to buy one. It's more expensive to train developers on how to use your framework than an existing standard. If you had one person developing just your infrastructure full time it would cost you 100K/y in salary, which is more expensive than the most expensive J2EE server will run you on average.

        Now I would like you to think, "Why don't we write our own database systems?" If we write our own system we wouldn't need to parse SQL. We could store the data in relation formats where it's good, and hierachial where it makes more sense to be hierarchial. The system would be faster be a very significant amount.

        The point is if you keep "reinventing the wheel" (I hate that phrase.) your competitors will beat you to market.

        I think I've covered two of the main points here.
        1) It can be cheaper
        2) It can be quicker to market.

        Who cares if it requires a cluster of Opterons to run, software has always cost more than mass produced silicon waffers.

        So, back to the main answer, which by now you probably can see, when to use EJB.
        1) If you need distributed transactions.
        2) If you need platform independance. (.Net clause)
        3) If it will let you get to market quicker.
        4) If you need declaritive security checks.

        If none of those ifs apply to your project, then you would be an idiot riding hype if you use EJB. As for my EJB projects, I can generally say I need all 4. You can't force Linux on clients because they don't have administrative people that will patch it like they do windows. You can't use windows because it isn't reliable as a server generally. Let them pick and live with their own decision is my philosophy.

    • Re:Worth Learning? (Score:1, Insightful)

      by Anonymous Coward
      EJBs (particularly Stateless Session Beans and Message Driven Beans) are a fine solution for distributed multi-tier architectures. They scale well, can be transparently clustered and provide integrated end to end security. Even Entity Beans (when used correctly) can be quite valuable for write-intensive applications.

      The biggest problem with EJBs is poor developer understanding of how to use them. Not just technical nuts and bolts, but problems such as innapropriate long-term use of Stateful Session Beans a

    • I had a great experience with them (Score:1, Interesting)

      by Anonymous Coward
      However you are correct in the sense that most of the people using EJB's have no clue of whats an "enterprise" application: they think that because their building a banking application (or worse a large website) that they are building an enterprise application. Most people I see using EJB's have no idea whats ACID let alone XA, they sometimes know what 2pc means but only its initials and not how it works.

      EJB's depend a lot on the tools as well I personally think WebSphere sucks, it looks good but it was ju

    • Re:Worth Learning? (Score:5, Informative)

      by icebattle ( 638355 ) on Monday October 27, 2003 @01:56PM (#7320748)
      I'm an architect working on a multi-million dollar enterprise app, and our experience with ejb thus far has been extremely positive. We steered away from entity beans, opting instead for a jdo layer. Much of the integration layer utilizes mdb's for bridging between an oracle backend and a db2 subsystem.

      With modest hardware we're competing quite effectively with the mainframe app we're replacing.

      Our worst choice was to use a Swing front-end instead of Struts.

      My advice for anyone getting into ejb development is DESIGN. DESIGN. DESIGN. Know exactly what you're trying to do. Prototype a lot. Test all the time. And get a quality dba, because the effect of solid db tuning will usually beat anything you can do at the app server level.
      • I understand avoiding entity beans, because they're a major pain and don't give any benefits. And the rest of EJB isn't nearly as painful. But what benefits are you seeing from using EJB? When I used EJB, our final design had removed all of the entity beans, didn't use message-driven beans, and used session beans, but didn't actually do anything with them that couldn't be done with a simple factory pattern.

  • The main mistake of EJB. (Score:5, Interesting)

    by Krapangor ( 533950 ) on Monday October 27, 2003 @01:05PM (#7320237) Homepage
    They confused complexity with usefulness.
    A system with complex rules isn't necessarily more powerful, but it's usually more difficult and error prone.
    Unfortunately this misconception is very common in computer science. People tend always to create complex APIs/infaces and protocols just to get a "powerful tools". The result is the security and error ridden state of the internet and computers we see these days.

    Strangely other hard sciences have seen these problems decades ago (sometimes even centuries ago) and changed their terminology and fundations accordingly. Take e.g. Mathematics with is based on 2nd order logic and set theory. And this started with Godel, Riemann, Abel and Gauss about 120 years ago. We have the same drive now in Physics with Wolfram and co. propagating simple cellular automata. Some people in string theory move in this direction, too.

    Unfortunately computer scientists seem to be immune to this amount of common sense right now. Perhaps they need some centuries of fumbling aroung with overly complex model, too, until they get back to earth.

    • Re:The main mistake of EJB. (Score:5, Insightful)

      by Glock27 ( 446276 ) on Monday October 27, 2003 @01:38PM (#7320575)
      They confused complexity with usefulness.

      I wouldn't put it that way. It may be that Einstein's dictum of "make it as simple as possible, but no simpler" wasn't followed. That I'd accept as a valid criticism of some of Java and it's libraries.

      A system with complex rules isn't necessarily more powerful, but it's usually more difficult and error prone.

      I'm not sure what you mean by "with complex rules". The essence of the matter is that developers want to use complex libraries and subsystems, in the hope that they'll solve equally (or more) complex problems. EJB's (and J2EE's) success or failure should be judged in that light. This is also true with regard to your "error prone" comment. The exact attraction of the J2EE architecture is that it should remove both risk and fragility from the system by using robust, tested code. There is a very large test suite that must be passed in order for an application server to be J2EE compliant. I think very few that have deployed J2EE applications would characterize the environment as "fragile".

      It certainly seems to have solved some need, because many projects are using it, many successfully. It certainly runs on the highest-end server hardware out there (up to over 100 processors in a single SMP box, which can be clustered).

      Unfortunately this misconception is very common in computer science. People tend always to create complex APIs/infaces and protocols just to get a "powerful tools". The result is the security and error ridden state of the internet and computers we see these days.

      First of all, J2EE systems haven't been the victim of many security exploits that I've heard of...Microsoft systems seem to be the usual victims. Both Unix and Java are Internet-hardened technologies that have stood up very well in real world use. Let's hear your alternatives now...

      • I think very few that have deployed J2EE applications would characterize the environment as "fragile".

        I've seen one J2EE implementation that doesn't fail gracefully, however, and doesn't provide useful feedback to the hopeful and rather under-qualified developers. The biggest fault I assign to these developers is using a commercial J2EE implementation complete with EJBs for a project that has only a few dozen tables and barely any data. They really could have gotten by with Perl scripts for this projec
        • I've seen one J2EE implementation that doesn't fail gracefully, however, and doesn't provide useful feedback to the hopeful and rather under-qualified developers. The biggest fault I assign to these developers is using a commercial J2EE implementation complete with EJBs for a project that has only a few dozen tables and barely any data. They really could have gotten by with Perl scripts for this project, but the government top-down dogma used to sell the project was "web based" with "enterprise java". Yup,

  • Incidental success... (Score:5, Interesting)

    by Fnkmaster ( 89084 ) on Monday October 27, 2003 @01:08PM (#7320257)
    If EJB can be used to put together a scalable, efficient, powerful system, it's surely only incidental. My problem with the EJB model in general is that there seem to be far, far more ways to build systems that don't scale, make inefficient use of resources, and generally suck than there are ways to make a system that scales, works and doesn't suck. Sure, you can say that of any programming language, I know that. But I'm looking at other "whole system" APIs that I can think of.


    For example, most GUI toolkits. Usually, you follow the examples and tutorials as a model, you read through the API docs, and you can build a system that works pretty well. Even many other kinds of enterprise software infrastructure - take TIB Rendezvous, or similar messaging systems - I've written apps with many of them that scale, are efficient and work well on the first try.


    I've seen several EJB apps written, and worked on a few myself, and you can read all the damned API docs, follow Sun's examples, read your app server documentation, and so on, and still, you just shoot yourself in the foot. This isn't the first book on patterns and anti-patterns of EJB usage, it's the umpteenth. Why? Because the EJB model was so poorly thought out prior to its implementation that if you follow the specs and build the kind of system they _seem_ to want you to build, it just doesn't work.


    Instead you need to have built 10 systems that don't work before you have a clue how to make one that doesn't. Frankly, it seems to me like more trouble than it's worth for what you get (which is basically transaction-aware objects, at least based on my knowledge from the EJB 1.1 era). If you just use session beans, if you don't use entity beans, if you don't do distributed transactions, if you don't use stateful session beans... then you can build an app that works.


    Great. I think the J2EE APIs have a lot of great, great stuff in them, but EJB just tweaks me out. Why the hell didn't somebody try using this hunk-a-junk before they released their 1.0 spec, or maybe their 1.1 spec, or howzabout the 2.0 spec? Maybe things are better these days, but if your API looks like it's supposed to provide a pattern for enterprise database applications, shouldn't it actually do that, or somehow redefine what the hell it's really supposed to be for?

    • I've seen several EJB apps written, and worked on a few myself, and you can read all the damned API docs, follow Sun's examples, read your app server documentation, and so on, and still, you just shoot yourself in the foot.

      I think EJB is one domain, whose programmers really would benefit from some kind of formal training on the architecture. This could be a few weeks at a reputable training class or a good apprenticeship program within companies. Enterprise apps aren't exactly something that can be pick
    • Why the hell didn't somebody try using this hunk-a-junk before they released their 1.0 spec, or maybe their 1.1 spec, or howzabout the 2.0 spec?

      You could ask that about a lot of Java APIs. I mean, they can't even get the basic collection classes right.

  • Does it tell you when NOT to use EJB? (Score:5, Insightful)

    by MillionthMonkey ( 240664 ) on Monday October 27, 2003 @01:14PM (#7320291)
    It's gotten to the point where people don't think you're doing "J2EE" if they don't see EJBs being used. If you don't need transaction isolation over a distributed system, EJB is overkill.

    The infrastructure for those systems are hard to write. The whole point of EJB is to have as much underlying general purpose infrastructure as possible already written for you, so you can plug your ad-hoc business logic on top. This puts development of these systems in the reach of a greater number of developers. But if you can write it yourself, you'll be better off. You'll be in control of more of the code, and won't spend your time messing with tuning parameters and configuration files for someone else's code. One exception is a distributed transactional system where it simply gets to be too much for you to reach your deadline. The other is a system that might be integrated into a larger system like that, that is already based on EJB. (Or the customer might be requesting EJB, maybe for a good reason.)

    I sat in on an interview once where we were explaining the architecture of a server product we sell, and the first thing out of the interviewee's mouth was "You don't use EJB? Oh I'm surprised- you should really be using EJB!" That killed the interview right there.

    • Indeed, it does. It's a major part of the book -- a good hunk of chapter one discusses whether you should use EJB at all (it's kind of a "cut through the marketing hype" sort of treatment). And they don't let up after that -- the authors don't like entity beans much at all; from the intro to Ch. 8 Bitter Alternatives:

      We won't really illustrate [ in this chapter ] how to use or misuse a major EJB feature. Instead, we'll show you why EJB entity beans should be avoided and suggest alternatives.

    • Hear, hear!

      Yes, too many people see J2EE as synonymous with EJB and vice versa. Of course, that's where the bulk of Sun and nearly everbody else's focus is, but strictly speaking just doing JSP and servlets with Tomcat is also J2EE.

      (And of course for small, non-critical systems you might well be better off going with something lighter weight like PHP.)

  • Bitter is right! (Score:2, Insightful)

    by Eros ( 6631 )
    Does anyone else think that it is messed up to create one framework that is suppose to handle business logic AND database persistant objects?

    Whatever happened to making frameworks that do one thing only and do it well?
  • I like my coffee like I like my women...

    Bitter.

  • Is EJB dying? (Score:5, Informative)

    by MSBob ( 307239 ) on Monday October 27, 2003 @01:25PM (#7320438)
    You don't have to be a Kreskin... blah, blah.

    That's how every good slashdot troll should begin. But if there is one technology that is currently at real risk of extinction in the Java world it is EJB. Almost every new J2EE project that I hear about steers clear from EJB towards simpler solutions such as plain servlet/jsp with JDO for persistence. Then you scale it horizontally through mod_jk or a hardware load balancer. No need for confusing (and restrictive) enterprise beans.

    Entity EJBs have been critisized many times and rigtfully so. Session beans I find are OK but for me (and my company) it's a case of "I really don't need them given the baggage of complexity and the restrictive nature of their API.

    Message driven beans are probably worthy of consideration but there isn't that much to them really. Certainly not something you couldn't implement on your own with plain JMS. I've done it, didn't take much time and it worked just as well as the specc'ed MDBs. And I don't have to run within an EJB container. I can deploy to Tomcat and have SonicMQ running remotely.

    Is EJB going to really take off? Seems that the spec was vastly improved but not all problems with the technology have been addressed and then there is the phsycological issue for many developers who had nasty experiences with EJB 1.1 development.

    I won't trash EJB they are a certain way to develop enterprise applications. I just find that I end up with much simpler design if I avoid them in lieu of something simpler. My preferred stack at the moment (assuming no legacy systems to integrate with) is as follows:

    • Struts
    • Hibernate
    • GLUE
    • Tomcat
    • JDOM
    • SonicMQ if I need messaging
    • Good DBMS
    And I'm good to go. Look Ma, no EJB!

    • Re:Is EJB dying? (Score:3, Informative)

      by saden1 ( 581102 )
      Excellent post!

      If I were starting a new project this is what I would use. Hopefully this would give some of you /. folks something to think about.

      + Eclipse (IDE)
      + Hibernate (JDO like Persistence)
      + Jetty (or Tomcat).
      + Spring Frame Work (struts is out).
      + Oracle (or your favorite open source DB).

      • Spring seems to be touted a lot lately. What are its selling points? I'd like to investigate it a bit more but I'm not sure what its "killer feature" is. Do they offer custom tags the way struts does?
    • Perhaps you can tell me what the compelling need for Struts is, then. I've looked at it, and it doesn't seem to do anything that's worth the added complexity of learning and using it, not to mention adding one more external dependency to the project... Then there's the documentation issue, it seems to be nearly as impenetrable as the XSLT spec.
      • For me it's custom tags mostly. But separating the form bean and the action I find annoying. But the custom tags do seem to cut down on the size of the jsp pages, so I put up with it. But I agree, struts should have been a hell of a lot simpler. I'm investigating webwork2 which some people seem to swear by these days. I'm going to check out what the fuss is all about.
        • Hmm. The custom tags didn't seem to do much that I couldn't write myself or find in pure custom tag libraries, but maybe I didn't look hard enough.

  • Story probably should have provided a link (Score:4, Informative)

    by mcc ( 14761 ) <amcclure@purdue.edu> on Monday October 27, 2003 @01:32PM (#7320517) Homepage
    To Bitter Java [slashdot.org], Bruce Tate's previous and somewhat less targetted book. I read this book and it was absolutely fantastic-- I would recommend it, and based on the pedigree I would say this new book is probably worthy of recommendation as well.

    Bitter Java went in exquisite detail into the various ways things can go wrong in Java development, and in Java-like languages, in an attempt to teach good design by counterexample (most of the book concerned real-life examples of what they called "antipatterns"). It is one of the better books on OO design I've come across. Unfortunately I accidentally left my copy on an airplane somewhere between Indianapolis and Dallas :(

  • Good database design is still essential (Score:5, Interesting)

    by GGardner ( 97375 ) on Monday October 27, 2003 @01:33PM (#7320532)
    The big lie with EJB, and all the OO RDBMS mapping and access tools, is that you don't need to learn anything about relational databases, modeling or theory in order to use them successfully. For some reasons, most developers are terrified that becoming a database expert means becoming a tie-wearing, COBOL-writing "business programmer". Perhaps this is because database theory and application is taught horribly in most Universities.

    Every failed EJB based system (and many failed non-EJB systems) that I've seen had poor database schema design at their heart. In almost every case, engineers familiar with OO design, didn't really bother to learn anything about RDBMS, perhaps because they felt them to be old-fashioned, and tried to ignore the database as much as possible, and put too much logic outside of the database.

    There's a lot to EJBs, sure. But you first have to learn the basics of good database design, for without that, you are hosed.

    • EJB uses OO centric ideas, which tend to neglect data modelling. Class modelling is what its all about, data is not at the center.

      You see it in the idea of entity beans that encapsulate data, and the higher layer of session beans that encapsulate process (i.e. business logic). It encourages you to not use RDBMS business logic (such as constraints, triggers and a sound datamodel).

      Lighter approaches such as the simpler "model-2" servlets, using plain JavaBeans as data access layer much more leads you to put
      • >EJB uses OO centric ideas, which tend to neglect data modelling. Class modelling is what its all about, data is not at the center.

        I think the parent is trying to say that very major problems can come from this view point no matter how good you are at EJB or Java programming.

        >It encourages you to not use RDBMS business logic (such as constraints, triggers and a sound datamodel).

        I never really understood this point. In any serious major project I've worked on, there is alway some secondary way to
    • But you first have to learn the basics of good database design, for without that, you are hosed.

      Agreed. It is also easy to argue that doing the database design first in a project rather than slapping it together as classes are created is the best approach. Normalization is important, too. I've seen a database where some tables had over fifty columns, where there were blatant opportunities to split the tables up into much more logical entities. But the developers didn't do it, and the software suffers

  • J2SE vs J2EE (Score:2, Insightful)

    by pong ( 18266 )
    I think Sun divided their developers into two camps. One camp would make a virtual execution platform with a nice associated language and a good core framework and they labelled it java/J2SE. The other camp was given the task of designing an enterprise application framework and they labelled it J2EE. The big problem is that the J2EE team decided (and probably for a good reason) that everything should be dynamic and runtime configurable and pluggable and extensible to the level that it became so dynamic that

  • Prevayler solves a very specific kind of problem. (Score:5, Insightful)

    by rossifer ( 581396 ) on Monday October 27, 2003 @02:13PM (#7320900) Journal
    Prevayler is a persistence golden hammer to those who have been converted. Here's an essay I wrote to add to the Prevayler wiki (but didn't have the permissions to add):

    Without a more effective query semantic, prevalence will be limited to a very small subset of the problem space currently solved with O/R solutions.

    The knowledge gap appears to be in the analysis of the value of SQL queries in programming and computational problem solving. My assertion: relational programming is actually different from object oriented programming and is more useful than OO for a number of problem types, including asking ad-hoc questions of the data set (very common for reporting, etc.).

    This feeling, that SQL and RDBMS's are somehow a "throwback" or an "obsolete" technology reveals a lack of understanding of the relational programming model. This feeling has also led to a lot of "trips around the block" (Yet another OO database, etc.). OO databases don't really catch on for anything because they don't solve real world problems better than relational DB's. Yet time and time again, OO databases are trotted out as the "road to freedom from SQL". SQL, appropriately applied, isn't any more confining than Java or any other programming language, appropriately applied. Unless you take a close look at one of the problems that SQL solves elegantly, however, this statement will not make any sense to you.

    Based on my experience, the biggest differences between the OO model and the Relational model include:

    • The relational model is not encapsulated, which allows even unanticipated questions to be answered after the system is complete without substantial/any modification to the system.
    • Relational optimizations (a.k.a. indexing) are the key to performant queries and the ability to simultaneously use more than one index (actually N) for query optimization has no useable analog in OO query programming (yes, you can maintain lists of lists on a per-query basis, but ouch!)
    • Once you have several dozen indices speeding things up, index maintenance in RAM in OO is harder than for a well-designed RDBMS (PostgreSQL, etc.). Both slow down the creation of new objects, but:
      • RDBMS's use a number of "tricks" to minimize the cost of row insertion and effectively minimize the code development cost of that insertion from the developer.
      • The OO developer, on the other hand, must take the time to insert each new object into each sorted collection of objects, complicating code and consuming lots of time.

    Basically, I accept the prevaylance performance numbers, simply because I can make any decent RDBMS perform queries 3000x to 9000x slower than nominal on a sufficiently large dataset by screwing around with the indices. What I don't accept is the claimed significance of your numbers. Who cares if your system is 9000x faster than Oracle + O/R for your carefully chosen example problem if my real world problem is 5x faster but requires 100% more java code and can't easily handle new report types? Most of the time, performance is one of the last aspects of a new system to get any attention, and IMHO, that's exactly the right emphasis for performance in system development.

    Let's propose a real business application with dozens of objects in a complex model and then throw a few million instances at it. Now let's start adding queries to the system and let's see who does better? I'll bet that I don't have to try very hard to get the queries 1) written faster and 2) executing faster against the O/R layer than you do against the objects in RAM, but then since I'm choosing the dataset, you know that's not going to be too difficult :)

    I'll freely admit that you guys have some really cool ideas, and I *really* like the idea for small apps that already use files for persistent state. Only problem is that none of the products I've worked on in the last ten years fit a mold that prevalence would make easier. If anything, your approach mak

    • I have done a lot of database work, and what I've not seen a Java tool do well yet is start from the SQL side of things - a really well written, fully optimized query, and then use that as a basis for mapping.

      Instead almost every O/R layer under the sun assumes that I just want to store objects in the DB. Almost never in several years have I in fact wanted to do that, usually I wanted the results of a good query to be represented for me somehow. I think this can be done in Java (after writing three O/R

  • Thoughts about j2ee (Score:3, Interesting)

    by akuzi ( 583164 ) on Monday October 27, 2003 @02:22PM (#7320982)

    I've been doing J2ee development for the last couple of years and on the whole I don't think EJBs give you many advantages but they do add a lot of confusion.

    The main problem is that it isn't clear the best way to use them, there are so many techniques and patterns out there but there is nothing you can point at that is the 'best practice' - it all depends on your application.

    The advantages of easily scalability of business objects over multiple servers is useful, but since the database is the main bottleneck in most enterprise applications the scalability of the business logic layer doesn't give you a lot. Also many applications require communication between the various clients (through the server) but since EJBs are designed to be location independent, there is no nice ways of communicating between session EJBs on various machines. It is possible to do it with message EJBs but it's not easy. Another thing to note is that you don't need EJBs to separate the business layer from the presentation layer, it's easy to do with normal classes. You also don't need EJBs to have the business logic running on another server - you can just use RMI.

    The automatic EJB transaction management is useful but since it relies on exceptions being thrown and it can get very confusing, and often isn't flexible enough - we seem to resort a lot of the time to UserTransactions.

    On top of that a complex database schema seems also impossible to map to Entity EJBs in a useful way. We have 300+ tables and the presentation layer needs all sorts of combinations of relations between the data that mapping the data into 'Entities' just seem to make data access inefficient.

  • Why EJB is chosen (Score:3, Insightful)

    by rollingcalf ( 605357 ) on Monday October 27, 2003 @07:19PM (#7323874)
    Managers are seduced by the hype, and their observation that "everybody else is doing it", so they order EJB to be used in the company.

    Programmers are seduced by the buzzwords, and want to be able to put EJB on their resume, so they will either actively encourage their management to choose EJB, or will use it for every imaginable task if it has already been chosen.

    In reality, over 95% of EJB applications could have been developed cheaper and faster and with less bugs if they used Java without EJB. You can get scalability, clustering, and failover with servlets, without the tedium of EJB. You can get persistence with JDO or JDBC facades, with better performance and simpler than entity beans. You can get asynchronous messaging by using JMS without EJB. You can get remoteness using RMI without EJB.

    But the reality doesn't matter. Both programmers and managers have been seduced by the hype and buzzwords, so EJB will live on even if it makes things ten times more difficult and expensive.

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