Maven, Java and RSpec

18 September 2008

java junit maven rspec testing

Since I've been back on the job, writing Java code lately, that means I've been testing Java code lately.

After living in the land of Ruby with RSpec, thinking about JUnit did not excite me. Thankfully I found the rspec-maven-plugin, which integrates straight into the maven test process.

I like rspec because it removes a whole lot of the cruft involved in writing tests. When I return to the specs weeks later, I can still read the intent. So often, with JUnit tests named with cryptic method names, it's difficult to ascertain exactly what's intended to be tested.

The beta-4 plugin on the repository is based on jruby-1.1.2, but in SVN I've updated it to support 1.1.4. I think there's still some more improvements to be made, such as respecting maven.test.skip and getting rid of the need for JRUBY_HOME pointing to a full installation. (Note: I did not write this plugin, I've just started contributing to it).

After a little configuration of the plugin in your pom.xml...

    <!-- jrubyHome points to the JRuby installation you wish to use (usually ${env.JRUBY_HOME}) -->
    <!-- sourceDirectory references where your RSpec tests reside -->
    <!-- outputDirectory specifies where the RSpec report should be placed -->

Now, just start flinging out specs in ./src/test/specs/.

This is a portion of a test against a JBoss-VFS VirtualFileHandler implementation, written in Java in

describe WarRootHandler do

  before(:each) do
    @context = RailsAppContextFactory.getInstance.createRoot( "ballast", File.dirname( __FILE__ ) + '/../ballast' )
    @root = @context.get_war_root_handler

  it "should have a rails:// URL" do
    @root.to_uri.to_string.should eql( "rails://ballast/" )

  it "should be resolvable through java URL handlers" do
    url = "rails://ballast/" )
    url.to_s.should_not be_nil

  it "should delegate for WEB-INF requests" do
    web_inf = @root.get_child( 'WEB-INF' )
    web_inf.should_not be_nil
    jboss_rails_yml = web_inf.get_child( 'jboss-rails.yml' )
    jboss_rails_yml.should_not be_nil

Deployers in JBoss Microcontainer

17 September 2008

deployers java jboss microcontainer

In order to deploy a Rails app, I've had to learn the innards of Microcontainer's deployer framework. After a few wrong turns, I feel like I've finally gotten a handle on it.

While we're all used to dropping in an .ear or a .war, and might think in terms of deploying these archive formats, that's ultimately one step removed from true deployment through MC.

Within MC, when you deploy a .war or an exploded WAR directory, the first step is something recognizes that the chunk you're deploying is roughly shaped like a WAR. I'll address that phase of deployment in a future post.

Knowing that the deployment is a WAR also tells MC to look in WEB-INF/ for meta-data descriptors, such as web.xml and jboss-web.xml. This is where true deployment of components starts. Deployment runs through a series of stages, with deployers setup to match particular files and stages, doing the right things at the right time.

One of the earliest stages is the PARSE stage. A deployer can be bound to this stage to be given an early chance to match, parse, and act upon any meta-data file. For normal WAR deployment, the WebAppParsingDeployer does exactly that. There's a nice hierarchy of classes to make parsing XML descriptors such as web.xml super simple.

The WebAppParsingDeployer is the bridge from a web.xml file sitting on the filesystem or in an archive to the MetaData deployment bits. The parser reads web.xml, and produces a WebMetaData object associated with the deployment. The WebMetaData is simply a nice object-tree representing anything you can denote in web.xml.

We also might have a jboss-web.xml meta-data in our WAR, and that is parsed during the PARSE stage by the JBossWebAppParsingDeployer. This deployer, like the previous, reads the XML file and creates, in this case, a JBossWebMetaData object.

Once we've parsed these .xml files, the container has enough information to build up the classpath for the component. Some of these deployers have also thrown off or modified some ClassLoadingMetaData, which describe paths that should be added to the classpath.

As the container enters the CLASSLOADER stage of deployment, other magic occurs to actually set up the classpath.

In the end, it's the JBossWebMetaData that drives the ultimate deployment, but what if we don't have a jboss-web.xml? That's where the MergedJBossWebMetaDataDeployer comes in. It looks for a WebMetaData, and a JBossWebMetaData if one has been parsed, and merges them into a singular JBossWebMetaData. I think it also mixes in any defaults that you have set for server-wide settings.

Additionally, as jboss-web.xml is parsed by JBossWebAppParsingDeployer, it will perform the merge itself. Additionally, magic is occuring to merge any annotation-based meta-data.

I'm a little fuzzy on the ins and outs of the CLASSLOADER stage at this point, but magic occurs there.

And our app still isn't deployed yet. But we're getting there.

Finally, we enter the REAL stage of deployment, which fittingly-enough, is where the actual deployment occurs. Hooray!

Our TomcatDeployer is hanging out there, waiting for JBossWebMetaData objects to appear. When it sees one, it goes to work setting up information for Tomcat to deploy a web-app. It configures everything in Tomcat from the information other deployers figured out from web.xml and jboss-web.xml and embodied in the MetaData.

It jams it into Tomcat, hits the big red "go" button, and port 8080 is serving you web-app.


In general, to deploy in AS5 using Microcontainer, you need some MetaData bits, and perhaps a bag of files/classes/resources. Nothing says they have to be bundled into a .war, or include some j2ee XML deployment descriptor. If you have other magical ways of bundling MetaData and resources, you're good to go.

Of course, Ales or Adrian may tell me I'm completely wrong. That's always a possibility. In fact, I'm sure I've got some things wrong, in reverse order, and otherwise mixed-up.

Here's a picture for you, though.


While discussing this on the Microcontainer user's forum, I discovered that there are indeed several errors and inconsistencies in the above.

Update #2:

New image, slightly new text to match the image better. Comments and clarifications still welcomed.

F3 is a beautiful thing

12 September 2008

comprehension eclipse java vi

Code comprehension. It's important when you jump into someone else's code.

Eclipse makes it easy, with F3, command-T, and shift-command-G.

Very quickly, you can jump through a maze of classes and interfaces, diving into details or seeing the higher hierarchy. I forgot how nice Eclipse can be. Particularly if you've got the viPlugin.

72 open files (and bless the JBossAS guys for including Eclipse projects and source jars).

Offline ain't that bad

06 September 2008

evdo satellite starbucks wifi

I'm in the process of moving to some farmland in Virginia. It's out in the boonies.

How far in the boonies? No cable. No DSL. GSM is sketchy.

Thankfully, I've moved my personal development to Git as noted previously, which works wonderously. With no TCP in the air, I can still commit, and push my complete history on to the repository-of-record when I do find some radio waves.

So, I spend my mornings at Starbucks using the heck out of their wifi and the afternoons in a small 4-square house surrounded by cows. I've seen various strategies and tools for turning off the internet for some predetermined amount of time, to allow you to focus without distractions. I've indeed found The Farmhouse Method to be great for focusing on coding, and not browsing porn blogs.

Next week, though, I'll take a half-step closer to being somewhat online. WildBlue delivered a dish and a modem to bounce some bidirectional internet signals off a satellite. At a stellar 1 watt broadcasting power. It's not going to be awesome, particularly coming off 6mbps DSL. The latency on interactive traffic is also debilitating. The speed of light is just too slow bouncing all the way up to the bird and back, plus the return trip for the echo.

I also plan to evaluate Alltel's "wireless internet" EVDO service, supposedly unlimited, but also probably not funneling between the mountains to my valley (or "cove" as we call them here in the south).

But then again, I get to wake up and drink coffee with the free-range cattle. That's a trade-off I'm willing to make.

And there's always Starbucks.

JGroups impersonating memcached

04 September 2008

java jboss jgroups memcached

I woke up and noticed that a memcached mode was announced by Bela Ban, the fantastically Swiss man who jogs waaay too much.

There's a lot of things in this world that can take advantage of memcached. Personally, I find this quite interesting, considering that memcached tends to be the cache-of-choice for lots of non-Java languages. For instance, fragment caching and model caching in Rails supports talking to memcached.

Or now, JGroups.

Another JBoss GitHub repository mirror

30 August 2008

git github java jboss jbossorg mirror svn

For those of you playing along at home, I've added jboss-deployers to my GitHub mirror set. Like the others, the 'vendor' branch is the one you want.

I'm adding JBoss projects to my mirror set as I trip across the need to browse their source. If there's a JBoss project you'd like to see mirrored out of SVN, drop the URL to the trunk of the SVN repository in a comment on this post, and I'll start slurping it.

And now, something slightly different

28 August 2008

java jboss jbossorg job jruby ruby

Back in May, I was a manager.

I feebly attempted to direct 8 great guys and gals to further the goals of After the Codehaus, you'd think I'd be able to help build an opensource community with fun and flair. But I came to realize that it's hard to build a community as an active effort. Instead, I think community develops as a by-product of a useful and well-run project. And that's under the control of the project leaders and contributors, not necessarily some external third party.

Back in May, I gave up being a manger.

Now, the day after Labor Day, fittingly enough, I'll be jumping back into the world of JBoss. But not as a manager. When I was burned out and felt like resigning, Mark Proctor and Sacha Labourey instead talked me into taking a sabbatical. And I'm truly grateful to them. Now, after unwinding for a few months, I asked to rejoin the team as an engineer. Through Sacha's patience and budget manipulation, I'm once again excited to go to work. I think JBoss should definitely be held up as a company that takes care of its people. They could've easily given me the boot, but instead they've been extremely kind and accommodating.

So, what will I be doing?

After talking to Java developers and Rubyists alike, my first goals are to look at Rails as just-another-way to write J2EE apps (or "JEE" I reckon, these days...). Yes, I know about (and plan to use) things like Warbler and JRuby-Rack. Both are good things.

But I also have full control of the deployment environment, to build a stack to make it happier than "build and deploy a WAR".

Through the miracle of AS5 built on JBossMicrocontainer, along with the awesome VFS bits, it should be possible to deploy a Rails app in-situ, right from your working directory. There should be no reason to have to build a WAR while you're hacking a rails app. And deployment to a server should still involve capistrano (in my opinion). Stick to the Rails way of doing things, but make it Java under the covers.

Various blog posts have shown Rails apps on Glassfish in 12, 10, or 5 steps. My goal is to get it down to 1 step. And you should magically be able to pick up and use all the wonderful JEE bits that maps to the Rails functionality the Railers of the world enjoy, without having to be aware of the JEE bits.

Speaking with Mark Newton (the guy who runs now), it seems sensible to view Rails as simply yet-another-programming-model for writing Java apps. The idea is to avoid leaky abstractions, so we're not having to write some psuedo RubyJava application.

Once we've got that base covered, then we can make fun and exciting Ruby bindings to all the powerful JBoss tools, such as Drools, ESB, Cache or MQ.

I expect to have a bit of fun with this. More fun than being a manager, certainly.

Raleigh RubyCamp

25 August 2008

redhat ruby unconference

Oh, fortuna!

I'm rejoining the Red Hat/JBoss mothership, doing rubyish things, and what do you know, but there's a RubyCamp at the RHT HQ in Raleigh on October 18th.

37signals and Ruby Row are sponsoring the event.

Space is limited to 200, but at the time of this posting only 57 have signed up. It's an unconference, so bring your own good ideas, and you can lead a session

Be a smarter patch monkey

25 August 2008

git metaprogramming ruby

A project I'm working on requires some hard-core monkey-patching of Rails internals.

Monkey-patching is a dangerous occupation, and liable to cause new and intriguing bugs into previously-tested sane code.

I've been working on a smarter patch-monkey, known as Lemur.

The goal is to allow monkey-patched methods (currently only instance methods are supported) to be written in modules that are mixed in (as modules are) but allowing redefinition of methods in the patchee by the patcher module.

I may be ignorant of some Ruby to make it happen, but I've resorted to alias_method and remove_method, along with a handful of Ruby's reflection methods to swap methods in a reasonable, clean, and auditable fashion.

The specs demonstrate how it works. Assume a basic class:

class BasicClass
  def some_instance_method()
    # ...

And a module to monkey-patch it

module PatchModule
  def some_instance_method()
    # ...

Normally, Ruby will prefer a locally-defined method over a module mix-in, so you can't just include your patch module in, even using class_eval.

So, invite in the Lemur.

Lemur.patch_class(BasicClass, PatchModule)

And voila! Your class is monkey-patched by the nicely self-contained module, plus, it's tracked.

Lemur.patched_classes # [ BasicClass ]

And even more cool, you can get some patch-audit information for each patched class:

Lemur.patch_records( BasicClass ) # [ array of PatchRecords ]

Each PatchRecord keeps up with the patched class, the patched method name, the actual replaced Method object, along with the patch module and the patch method.

A total of 40min has been spent writing the code so far. The idea is to add better auditability, unpatching, and dealing with class methods, not just instance methods.

Now, when you encounter a weird bug, you can ask the Lemur where the oddness might've originated.

Want to pitch in and do some meta-programming to make future meta-programming less scary, fork my git repository and send me some pull requests.

GitHub Mirrors for some JBoss Projects

21 August 2008

git github java jboss jruby svn

In addition to the previously-mentioned JRuby mirror from Codehaus SVN to GitHub, I'm now also mirroring:

All are trunk-only mirrors, not picking up branches or tags. Since the JBoss repository path has about 77,000 subversion revisions, and at one point held any and all JBoss software ever written, I have not mirrored it in its entirety. Instead, I've only grabbed back to revision 77,200. It'll mirror going forward, but the github repository does not include any ancient history.

For those of you playing along at home, the way to fetch just a cauterized "tip" from SVN to a git repository is to mirror as before, but for the initial "git svn fetch" command, add a SVN-style revision range

git svn fetch -r77200:HEAD

For me, at least, trying to fetch the tip revision for the directory resulted in failure. Going back a few revisions, and using a range that includes HEAD worked much better. Then just push to GitHub has normal, and start your rebase/push cronjob.

The JBoss projects are updated from SVN every 15 minutes. But we're updating from the anonymous SVN repository at JBoss, which itself is delayed from the developer repository by some amount of time. So, ultimately, the GitHub mirror should be mostly up-to-date, but could lag behind actual developer commits by up to and hour, I reckon.

If you're wanting to track these repositories using my git mirror, only track the vendor branch. I make no claims about the stability or sanity of the 'master' ref at any point in time. I will make sure 'vendor' exactly matches the Subversion history, though.