Netuality

A mini-review

The book already has stellar ratings on Amazon, JavaRanch and other select places, and after reading a few chapters, the only thing I can do is add this post on the praise list.

Why only a few chapters ? Well, you see, this is not exactly the type of book that you read from cover to cover, it's in fact a 720-pages solid collection of JUnit best practices, the most comprehensive you'll ever found in organized, written form. Until now, I have found precise answers to all my JUnit questions.

The book is organized in three big sections weighting some 200-250 pages each. The first one ('The building blocks') is hugely useful if you are a JUnit newbie or even an absolute beginner. It's a detailed introduction to everything you'll need to know in order to start using JUnit: basics, usage in mainstream IDEs, testing patterns, managing test suites, test data and troobleshooting advice. Even seasoned programmers will find useful pieces of advice. I especially liked the 5th chapter ('Working with test data') : an exhaustive description of all the possible ways of organizing your test data. To be honest, it's one of the few chapters from the first section, that I've really read.

The second part ('Testing J2EE') covers testing of XML, JDBC, EJB, web components (JSP, servlets, Velocity templates, out-of-container testing & such) and J2EE applications (security and again some webapp testing – pageflow, broken links, Struts navigation). I can't really pronounce upon this section since I've read only a few subchapters (DBUnit and some related JDBC testing, as well as a few pages from the web testing chapter). But every piece of advice I've got was rock solid.

I've read in its entirety the third part ('More JUnit techniques'). Under this bland title you'll find a group of not-so-common JUnit info such as usage of GSBase addon (funny that I wasn't aware that such a useful addon exists). There's also an intriguing 'Odds and ends' chapter containing some interesting recipes (here's a good one for the QA-freaks like me : 'verify that your test classes adhere to basic syntax rules of JUnit' – sure, why not ?).

Something that I've really missed is a chapter dedicated to mock objects recipes. Yes, there is a quick explanation in the first section – and a reference to Easy Mock or some other mocking API pops now and then in different chapters – there's even an essay about mocking at the end of the book. But the main mock objects dish isn't there. I would've also loved to see some automated GUI-testing recipes (Abbot, Marathon & related tools). But then again, it's a >700-pages book so I'm probably asking too much.

To conclude, 'JUnit Recipes' is the best JUnit book I've ever came into contact with and it supercedes on my list 'JUnit in Action'. Which, interesting enough, was published by the same Manning almost a year ago. Can't have too many good JUnit books, don't they ?

Disclaimer : this review is based on the MEAP draft. Things might be (a little) different in the final version.

From a documentation point of view, Hibernate is one of the most notable exception in the world of open-source LGPL'ed projects. Its website offers a plethora of information, from solid documentation (the reference has no less than 141 pages) and various FAQs to sample projects and third-party resources. The forum is quite active and you may get answers to tricky questions. Or a little bit of rough treatment in case you haven't RTFM – but that is understandable, given the number of questions that the authors have to answer every day.

Under these circumstances, one might wonder what Gavin King (Hibernate founder) and Christian Bauer (documentation/website maintainer and Hibernate core developer) can add in order to be able to write a 400-pages book about Hibernate. I mean – sure – only by joining the reference documentation, different FAQs and guides, one can easily 'extract' a hefty 'manuscript' with more than 200 pages.

Well, I am extremely glad to tell you that this is not the case. The book not only gets you up to speed with Hibernate and its features (which the documentation does quite well). It also introduces you to the right way of developing and tuning an industrial-quality Hibernate application. I consider myself a pretty seasoned Hibernate developer, being familiar with the API since its 1.2 version in Q1-2002 (if I remember well the first app when we used Hibernate). However, I was proved wrong by “Hibernate in action” which describes best practices and even API features that were unknown or vaguely known to me. That is, until now.

The first chapter, in the good tradition of all first chapters in the world, is an introduction. It's a very well written introduction about why do we need ORM solutions in OO applications. The chapter explains the O/R impedance mismatch, while declaring quickly that OODB suck (immature and not widely adopted). Wel'll also find out that EJB also suck from a persistence point of view (for various reasons). Which can be quite a surprise knowing that Gavin is one of the authors of EJB3.0 specs. Or, on the contrary, this will explain a lot of things in the new EJB specs.

Now that we have cleared the “why Hibernate” issue, let's continue to the second chapter. Which – tradition obliged – is a “Hello, world” and a “Let's get started” chapter. Here you go, almost 50 pages later you should be able to write simple Hibernate-based persistence layers and integrate within an application server, like for instance … Jboss ! Humm, well, why not ? They are sponsors of the Hibernate project, after all.

In the 3rd chapter, our fresh knowledge will be put to good use by starting the development of an online auction application called CaveatEmptor. This app will follow our reading progression and will grow bigger and smarter chapter by chapter. But for the moment, we are at the inception phase. What gives : a little bit of analysis, a stylish class diagram of the domain model and the resulting mapping file. And if you thought (based on 2nd chapter) that the mapping file is very intuitive and simple, you're in for a big surprise : it is, indeed, intuitive and simple ! Quite bizarre for an open-source project. As a matter of fact, the mapping file is one of the pivotal elements of Hibernate, since it addresses directly the O/R impedance mismatch, a recipy for transparent linking your POJOs and the constrained relational model. No wonder that a big part of this chapter is aimed at explaining why and how the mapping works in Hibernate. You'll see how class associations and inheritance translate at the metadata and mapping level. You'll start to understand the things that you took for granted in the previous chapter and you'll have that pleasant “uuh, I see” chain reaction. Hold on, it's just the beginning.

Because chapter 4 is going to explain once and for all the lifecycle of persistent object in Hibernate, their behavior from a persistence point of view as well as the available fetching strategies. And if you thought you already knew everything by heart from the documentation … well, maybe you do know everything by heart. Nevertheless, it's very well synthetized in chapter 4 and I'll recommend it anytime to a coworker eager for Hibernate knowlege.

In the next chapter (the 5th) the rollercoaster slows down a bit. That is, if you already know the behavior associated with the four possible isolation modes in transactions, what are the different types of locking, what (the hell) MVCC means and the importance of transaction scopes. Chances are you already know some of this stuff quite well, but everybody needs a refresher from time to time, especially when it's well explained and when it comes with versioning and caching (1st and 2nd level) in Hibernate as a desert. By the way, I thought that OSCache supports clustering, not only SwarmCache and JbossCache, as stated in the book. There's even a thoroughly explained example of using JbossCache as a level 2 clustered cache for Hibernate, but it shouldn't be too hard to convert to other types of caching systems.

Now, if I were the author of the book, I would have placed chapter 6 before chapter 5. But I am not the author, which is quite fortunate for you dear readers since Christian and Gavin are much more competent than me at writing books about Hibernate (and probably at some other unrelated domains). They have decided to go back to mapping in chapter 6, after the short transaction/caching intermezzo. Well, they should know better… it's time for a serious dose of advanced mapping. This chapter is attacking interesting subjects such as custom mapping types (simple or composite) and (finally) the mapping of collections. Special guests stars: the whole gang of “sets, bags, lists and maps”, together with explanations about their relational equivalent (associations, associations and associations !). Oh and yes “polymorphic association” (section 6.4.3) – I wasn't even aware that Hibernate is able to do that… guess I'm not that 'seasoned' (as a Hibernate developer) after all.

The 7th chapter is about “Retrieving objects efficiently” : about 45 pages for the 'retrieving' part and 6 pages for the 'efficiently' part. Fair enough ! You'll learn how to master basic HQL queries (parameters, pagination …). You'll get a grip on the query by criteria API, as well as on advanced stuff such as dynamic queries, filters, subqueries and native SQL (very powerful). At the end of the chapter there's the Hibernate-specific solution for the n+1 selects problem, query caching and result iterators.

Following this wealth of useful knowledge, the 8th chapter starts a bit dry. Nevertheless, after a short introduction about Hibernate in managed environments, you'll find yourself again in the land of advanced programming techniques : application-level transaction implementation ! This is mostly new stuff (at least for me) – a great collection of best practices for transactional behavior management in industrial-quality apps. Somewhat unrelated but still interesting, the chapter ends with legacy schemas integration and a smart implementation example for audit logging.

The 9th (and last) chapter is about the roundtrip development in Hibernate using the classical toolset : Middlegen and/or hbm2java and/or XDoclet. All the available techniques are presented in a very detailed, step-by-step manner.

Wait : don't close the book, there's more ! Ignore Appendix A (a short and rather uninteresting document about SQL fundamentals – that is, if you know SQL). Appendix B contains mildly un-fascinating ORM implementation strategies pour les connaisseurs (come on guys, I'm just a dumb user). But – Appendix C is a great collection of real-world stories and by all means read them all ! Especially the last one, a treasure of hard to find knowledge (no spoilers, please…).

In the end, I have to confess that there is something truly interesting about 'Hibernate In Action' : albeit very technical, it reads astonishingly easy – and this kind of books is unfortunately very rare nowadays. My congratulations to the authors for this excellent piece of work – it was worth the wait.

As for you dear potential reader, if you already know all the information detailed in the book, I bow before you, great Hibernate wizard. But if you don't, what are you waiting for ? Because, if you're going to read only one technical book this summer, make sure that it's 'Hibernate In Action' (or, at least chapters 6,7 and 8, if you are that good !).

My first contact with Tapestry was more than 18 months ago. Back then, I was interested to find a web framework for integration with our custom Avalon-based (using the now-obsoleted) Phoenix server*. The web interface was ment to be backoffice stuff, for simple administration tasks as well as statistics reports. Given that the data access and bussines logic were already developed, we were looking for something simple to plug into a no-frills servlet container such as Jetty. we managed very easily to integrate Jetty as a Phoenix service and pass data through the engine context. But when we finally integrated Tapestry [into Jetty [inside Phoenix]] and make it display some aggregated statistics, the project funding was cut and the startup went south. But, that’s another story and rather uninteresting one.

Meanwhile, things have changed a bit. Tapestry had become a firsthand Apache Jakarta project, the Tapestry users list is more and more crowded, and again I see it used in my day work (by Teodor Danciu, one of my coworkers and incidentally author of Jasper Reports) and doing some moonlighting by myself for an older web project idea. And there is exceptional Eclipse support via Spindle plugin. While the ‘buzzword impact’ on Tapestry on a Java developer CV doesn’t yet measure up with Struts, this framework has obviously gained a lot of attention lately.

So, what’s so special about it ? If I’d have to choose only one small phrase I’d quote Howard Lewis Ship, Tapestry lead developer, from the preface of his book ‘Tapestry in Action’:

The central goal of Tapestry is to make the easiest choice the correct choice.

In my opinion this is the weight conceptual center of the framework. Everything, from the template system which has only the bare minimum scripting power, passing through the componentized model, up to the precise detailed error-reporting (quite unique feature in the opensource frameworks world) gently pushes you (the developer) to Do The Right Thing. To: put logic where it belongs (classes not templates), organize repetitive code in components, ignore the HTTP plumbing and use a real, consistent, MVC model in your apps (forms are readable and writable components of your pages). You don’t need to be Harry Tuttle to make a good Tapestry webapp, just a decent Java developer is enough. That’s more than I can tell about Struts …

Coming from a classic JSP-based webapp world, Tapestry is really a culture shock. The most appropriate way to visualise the difference is to imagine a pure C programmer abruptly passing to C++, into the objects world**. For a while, he will try to emulate the ‘old’ way of work, but soon enough he’ll give up and start coding his own classes. However, this C programmer will have to make some serious efforts, not necessarily because OOP is hard to leard, but in order to break his/her old habits.

“Tapestry in Action” is your exit route from the ugly world of HTTP stateless pages and spaghetti HTML intertwingled with Java code and various macros. It’ one of the best JSP detoxification pills available on the market right now.

The first part of the book (‘Using basic Tapestry components’) is nothing to brag about. It’s basically an updated and nicely organized version of the various tutorials already available via the Tapestry site, excepting probably some sections in chapter 5 (‘Form input validation’). By the way, the chapter 5 is freely downloadable on the Manning site and is a perfect read if you want a glimpse of the fundamental differences between Tapestry and a classic web framework (form validation being an essential part of any dynamic site). However, if you want to go over the ‘Hangman’*** phase you really need to dig into the next two book sections.

The second section ‘Creating Tapestry components’ is less covered by the documentation and tutorials. I’m specifically pointing here to the subsections ‘Tapestry under the hood’ (juicy details about pages and components lifecycle) and ‘Advanced techniques’ (there’s even an ‘Integrating with JSP’ chapter !). While it is true that any point from this chapter will generally be revealed by a search on Tapestry user list or (if you’re patient) by a kind soul answering your question on this same list, it’s nethertheless a good thing to have all the answers nicely organized on the corner of your desk.

The third and last chapter (‘Building complete Tapestry application’) is a complete novelty for Tapestry fans. It’s basically a thorough description of how to build a web application (a ‘virtual library’) from scratch using Tapestry. While the Jboss-EJB combination chosen by the author is not exactly my cup of tea (I’m rather into the Jetty+Picocontainer+Hibernate stuff) I can understand the strong appeal that it is suppposed to have among the J2EE jocks. Anyway, given the componentized nature of Tapestry, I should be able to migrate it relatively easily if I feel the need for it. The example app is contained in a hefty 1Meg downloadable archive of sources, build and deployment scripts included.

To conclude, ‘Tapestry in Action’ is a great book about how to change the way you are developing web applications. The steep learning courve is a little price to pay for a two or three-fold improvement in overall productivity. And this book should get you started really quick.

*Which AFAIK is still used at our former customer.
**There were some posts on Tapestry user list on about a certain conceptual ressemblance with Apple’s WebObjects. I can’t really pronounce upon this because I do not know WebObjects, but the name in itself is an interesting clue.
***’Hangman’ is the Tapestry ‘Petshop’ (although there is also a ‘real’ Tapestry Petshop referenced in the Wiki).

One of my current responsibilities is to maintain an internally developed plugin, used by various members of the team to generate code from the analysis model. As far as I can tell by the webstats of the update site, every version is downloaded by 18 people, a small but heterogeneous user base.

My biggest problem is the Eclipse version. The analysts are not exactly Java geeks waiting anxiously for nightly builds of Eclipse, they use a 'standard' 2.1.2, mainly because it's stable and well internationalized. Things go wilder in the programmers team : versions ranging from conservative (2.1.x) to liberal (3.0M4) and even the occasional dumbass with the latest integration build (that would be me, of course).

The 'enhanced binary compatibility' in 3.0M7 came as a relief, diminishing the need to switch between Eclipse versions in order to develop the plugin or work on other tasks. Well, I still have to briefly test the damn thing on Eclipse 2.1.x before releases. However, running simultaneously two or three Eclipse instances is no piece of cake for my 512Mb laptop (I still haven't found who I have to kill here in order to be awarded a memory upgrade). Unfortunately, checking out the plugin source into M7 has shown the invisible ugly face of 'binary compatibility': the plugin doesn't compile.

There are just a handful of lines of code, some emphasizing differences in Eclipse API which are somehow hidden in 'compatibility mode', some effectively showing small bugs in plugin behavior. But the real issue here is that I cannot really develop the plugin in M7 until I manage somehow to compile it, while not losing downwards compatibility.

Let's dissect one of the compilation issues. The bummer concerns automatic opening of an editor (or focus if already opened) when clicking on its reference (somehow similar to what happens when you Ctrl+click on a class name in JDT). In the older API it was a question of page.openEditor(file); where page is a IWorkbenchPage and file is an IFile. This simple stuff worked well until 3.0M4, then (M5) things changed to page.openEditor(new org.eclipse.ui.part.FileEditorInput(file),editorId); where FileEditorInput implements (among others) an IEditorInput. While this is certainly nice because you may directly link editors to something other than files***, obviously the old code does not compile under M7.

Maintaining different projects for 'old' and 'new' style projects for 10 or so lines of code is obviously overkill. Second solution – via reflection, but it would mean more than few lines of code and the result would not exactly be comprehensible nor maintainable. Only thing left : use a scripting language.

Of course I could have taken any decent scripting language embedded in Java. Decision to go with Groovy was taken mainly because of its coolness factor, but I am sure the idea will apply easily with Jython (big favorite of mine) or the performance-aware Pnuts, for instance.

In a nutshell, you have to execute a line of code depending of the current Eclipse version (it's a little bit trickier, but we'll discuss later about it).

groovy.lang.Binding binding = new Binding();

binding.setVariable("page", page);

binding.setVariable("file", file);

groovy.lang.GroovyShell groovyShell = new GroovyShell(getClass().getClassLoader(), binding);

if (newPlatform)

{

	return groovyShell.evaluate("page.openEditor(new org.eclipse.ui.part.FileEditorInput(file),editorId);", someExpressionId);

}

else

{

	return groovyShell.evaluate("page.openEditor(file);", someExpressionId);

}

It's basically a vanilla flavored ripoff of the Groovy embedding example from the docs. The boring part : caching the binding, hiding everything behind a nice facade, is left as an exercise for the [interested] reader. Remember to pass the classLoader of the current class, do not create a GroovyClassLoader out of nowhere or you'll end up dealing with Eclipse own class loader, which means trouble for simple tasks like these.

How do we know that the Eclipse version is the 'new' or the 'old' one is not that simple because remember : 'old' means 2.x up to 3.0M4. So finding out Eclipse SDK version is not enough, you have to find out another discriminant which in our case is the 'org.eclipse.ui.ide' plugin. Result:

boolean newPlatform;

//find out if we are inside a new or an old platform

PluginVersionIdentifier pvi = Platform.getPluginRegistry().getPluginDescriptor("org.eclipse.platform").getVersionIdentifier();

newPlatform = pvi.getMajorComponent() >= 3 && Platform.getPluginRegistry().getPluginDescriptor("org.eclipse.ui.ide") != null;

No, we are not ready to deploy yet. A small trick has to be performed or the plugin won't start under older versions of Eclipse. We had to add some new plugins to dependencies (in the pligin descriptor) such as the aforementioned 'org.eclipse.ui.ide', obviously the older versions of Eclipse will not find it, hence block our plugin activation on startup. In order to overcome this, you have to add (by hand !) a lesser known attribute ('optional') in the corresponding tag from the plugin.xml file : <import plugin=”org.eclipse.ui.ide”/> becomes <import plugin=”org.eclipse.ui.ide” optional=”true”/>. Now, the plugin is ready to be deployed.

For those brave enough to dare distributing such a plugin via an update site remember to 'cheat' by not allowing new plugins such as 'org.eclipse.ui.ide' in the feature.xml file (again, delete by hand). The 'optional' attribute doesn't help in this case. Go figure…

I hope that some of you will find useful this recipe for maintaining compatibility between different Eclipse versions with minimum of fuss. However, please note the specific prerequisites for this type of solution :

• there are only simple 'few-lines' modifications
• the code is not expected to evolve a lot in the 'affected' areas
• the evaluated code is not in a performance-sensitive area

***Interesting enough, this was one of the reasons I recommended against adopting RCP in one of our apps, a few weeks ago. It's nice to see that – now – the mechanism linking editors and resources is MUCH more flexible. Anyway, this won't probably change the decision of not using RCP because the main issue it's the volume of code we have to change. Development of one of the app modules started almost a year ago and the animal it's already sold and deployed on different production sites: upgrading would be a real nightmare. Maintaining a fork of the app is not an option either. Well, I guess we'll just have to cope with 'plain old' Jface and SWT.

PS After some days of 'silence', I have noticed from the logs that most popular posts on my blog are those concerning Eclipse plugins and Manning books (I seem to have a nice Google ranking on these topics). So, expect more of these (I am reading the MEAP of 'Tapestry in action' – a review should be up shortly).

Eric Clayberg and Dan Rubel, both from Instantiations (the company which is developing and distributing SWT-Designer and Codepro, two very good payware Eclipse plugins) are preparing the book “Eclipse: Building Commercial Quality Plugins”, which should be published by Addison Wesley in 2Q 2004. Draft chapters are available at qualityeclipse.com.

Eclipse powered is a site by Ed Burnette, co-author of Eclipse in action at Manning. The new book will be targeted at building application architectured around RCP (Rich Client Platform). Unfortunately, the project is currently on hold (no reference about it on Manning either !), but the site has a nice, albeit short, collection of links to RCP resources. There also is an associated Sourceforge project with 4 example plugins, nothing very “rich-client” yet. Hope that's going to be published this year, because RCP is a very hot topic. Next week, I'll have my first RCP assignment – an integration feasibility study to establish whether we're going to use RCP as an alternative container for the supply chain&procurement modules of an ERP targeted to agro-industrial customers (the current container is a simple collection of tabs and a menu). It's going to be a fun week