thread dump

Thanks to the folks who commented on yesterday’s post I have managed to overcome the assign problem and of course the answer was very simple: I had an inconsistent set of components installed in NetBeans and GlassFish.  I was using NB 6.5 together with components downloaded from the OpenESB site. 

The best solution is simply to download the complete NetBeans/GlassFish/OpenESB combination from the OpenESB downloads page and work with that. On the download page the top section contains the GA (stable) GlassFish ESB / NetBeans combination, and the nightly build of the latest (unstable) additional components (i.e. binding components, service engines etc.) which match this GA release.

The next major section on the page contains the GlassFish ESB v2.1 downloads (milestone 1 at the time of writing), which are not yet considered stable. I grabbed the 2.1 release, plus the HL7 BC (and NB design-time modules) from here.  Installation was completely pain-free.  I particularly liked the way the additional components are packaged as a jar-based installer – very nicely done. 

Because the main package is a GlassFish ESB bundle, it installs by default to a non-standard path: C:\GlassFishESB. Everything is installed under this directory, including the configuration files for NetBeans, which would normally be placed in your home directory (under .netbeans). Presumably this is done to allow parallel installation with a stable NetBeans/GF without either interfering with the other. What this means, of course, is that all your preferences (editor settings etc.) are not transferred. This is easily fixed, manually, by copying over the stuff from: C:\Documents and Settings\<user>\.netbeans\6.5\config\Editors to C:\GlassFishESB\.netbeans\glassfishesb\config\Editors

Anyway, back to the BPEL issue.  A clean rebuild of everything was sufficient: the CA deployed to GF, and it ran fine.  I used Hermes JMS and watched the test messages arrive on the queue. Now I can push ahead and explore more of OpenESB and BPEL.

After far too many cycles staring at code, building, deploying, debugging and undeploying a pretty simple composite application, the damn BPEL assign activity still causes selectionFailure at runtime.

The BPEL is trivial, and the BPEL copy elements for optional elements in the source schema are marked with the ignoreMissingFromData attribute.  I have rebuilt everything from scratch.  I know the redeployments are successful because the error reports points to the correct line following an edit and I can use the BPEL debugger to step through the assign, eventually failing on the optional element.

I was given the hint about the ignoreMissingFromData attribute by Michael Czapski, in a blog comment.  Googling around for more help, I came across a few other postings, and discovered that the attribute could be placed at the process level or at the individual copy activity level. Jeff Sexton also has a nice post on the assign issue.

In Michael’s tutorial he does in fact place the attribute at the process level (see p.95 of the PDF document which accompanies his tutorial). Placing it at the process level is not very attractive because it will mask the absence of mandatory fields.

When placed at the copy element level, it seems to fail. Here’s the error I see, as output in the GlassFish console window:

BPCOR-6151:The process instance has been terminated because a fault was not handled; Fault Name is {http://docs.oasis-open.org/wsbpel/2.0/process/executable}selectionFailure; Fault Data is null
com.sun.jbi.engine.bpel.core.bpel.exception.StandardException: I18N: BPCOR-3023: Selection Failure occurred in BPEL({http://enterprise.netbeans.org/bpel/HL7Processor/bpHL7Processor}bpHL7Processor) at line 28!
BPCOR-6129:Line Number is 26
BPCOR-6130:Activity Name is Assign1

Note the line numbers in the above report: the first of these (line 28) is where the selection failure actually occurred, line 26 is the opening tag of the enclosing assign activity element.  Here’s a shot of the source so you can see the corresponding line numbers. I placed all the optional elements together at the start of the assign:

So why doesn’t this work? Is this a bug? Perhaps I’ve run into something which only works in the JavaCAPS product and not in OpenESB?  Shame.

Another unfortunate discovery is that the OpenESB UI in NetBeans 6.5 doesn’t seem to support adding the ignoreMissingFromData at the process level.  In Michael’s PDF he selects the top-level BPEL process scope and uses the property panel to set this attribute.  It doesn’t appear to exist in NB 6.5. In the shot below I’ve tried to capture the same UI as in Michael’s tutorial:

Note there’s nothing below the ‘Documentation’ entry: presumably this is additional UI support which you get in the commercial JCAPS product. I’m not that concerned with the missing UI, as long as I can add the attribute in the XML source.  So I edited the BPEL XML, using Michael’s tutorial source as a guide. It’s easy to add the process-level attribute; only the namespace prefix had to be changed:

<?xml version="1.0" encoding="UTF-8"?>
<process
    name="bpHL7Processor"
    xmlns:ns3="http://www.sun.com/wsbpel/2.0/process/executable/SUNExtension"
    ns3:ignoreMissingFromData="yes"
    targetNamespace="http://enterprise.netbeans.org/bpel/HL7Processor/bpHL7Processor"
    xmlns="http://docs.oasis-open.org/wsbpel/2.0/process/executable"

So another clean/build/deploy and … it still didn’t work. So now I’m stuck, and I hate being stuck. It’s almost enough to put me off the product.

The impression I get is that BPEL is great for very simple maps and transforms, but anything complex quickly becomes awkward. I haven’t gone beyond ‘simple’ so far, so I’m getting a little concerned. The pretty visual tools and NetBeans integration are cool, but the complexity overhead seems high. It reminds me of Microsoft’s BizTalk product from a few years back – a lot of fiddly config, and not being able to ‘see the wood for the trees’. 

But I want to persevere with OpenESB: something about this product suggests that you need to reach a certain level of enlightenment, after which everything becomes clear and the benefits outweigh the overheads. I’m just not there yet.

As well as looking at Apache Camel for healthcare integration, I have also been spending time with Sun’s OpenESB product.  OpenESB is the open-source counterpart of the Java CAPS product, a mature and well-supported Enterprise Service Bus (ESB) built on the Java Business Integration (JBI) standard.

OpenESB is delivered along with the GlassFish application server (v2) when you install the SOA extensions to the NetBeans IDE.

Michael Czapski of Sun is an excellent source of information on healthcare-related application of the CAPS / OpenESB product line. He has created a really substantial demonstration project based on a healthcare integration scenario. His blog entry and the associated downloads (and screencast) are well worth getting hold of.  The screencast and writeup are based on Java CAPS, the commercial product which provides a few nice UI improvements and I believe some additional tools which the OpenESB product does not have.

I decided to go through Michael’s complete tutorial, using NetBeans 6.5 and the bundled OpenESB / GlassFish combination, building the solution and making notes as I went along. I’ll put the source code for the NetBeans (6.5) and OpenESB project group up on a publically available Assembla Subversion space (URL to follow), in the hope they may be useful to others who want to use OpenESB to do a similar thing.

As already mentioned, the differences between Java CAPS and OpenESB are superficially small, so if you are already familiar with one or other product you probably only need Michael’s notes and material. However, if you’re relatively new to OpenESB (as I am), there are a few places where the absence of JavaCAPS tooling means you need to know what you’re doing to patch-up the OpenESB solution.

Getting Started

My first big lesson was getting a correct / compatible set of NB plugins and libraries installed. The zip archive provided by Michael appears to contain everything you need, including the XSDs, NB plugins and encoder libraries. As the article was published very recently, I assumed these were the latest versions so tried to configure my NB 6.5 instance using these.

I followed the instructions for installing the encoder library (first uninstalling the existing one), then installing the NB plugins. However, the plugin installation just wouldn’t go ahead:

I tried various combinations but in the end had to uninstall GlassFish v2 and run the NB installer again to reinstall GF plus the OpenESB bits. Fortunately, this is actually quite a quick process, and puts everything back as it was.

I won’t go through all my subsequent false-starts, but simply tell you to download a matched set of the latest versions from this location:

http://download.java.net/jbi/binaries/open-esb-full-install/nbm/latest/

The components here should all be compatible. It really is best that you download and install these yourself, so I won’t put them in the Assembla SVN space.

Doing without the Java CAPS Wizards

The most obvious differences when watching the screencast are the degree to which the commercial product contains wizard steps and conveniences for generating all the configuration items. Reasonable enough I think, and so far I have been able to complete every step using OpenESB and NetBeans 6.5.

When creating the concrete WSDL definitions with the HL7 bindings, the wizards in the Java CAPS product (seen in Michael’s screencast) do make the whole process slightly simpler. But if you take a little time to understand what these wizards are actually doing in the generated WSDL, it’s not too hard to complete the steps manually.  That’s easy to say now, but I should ‘fess-up and admit that it took me a little while to spot what I hadn’t done, a couple of times.

For example, once I’d completed the HL7Consumer_CA_A01_A03Delim_HL7In WSDL (sorry Michael, I’m not a big fan of your naming convention!), I simply couldn’t add it to the Composite Application design surface: the tutorial document instructions didn’t appear to work. I could see the WSDL in the list of available WSDLs and select it – but could not add it to the canvas, and couldn’t see any error message to tell me why.

After a cup of tea and a biscuit and a bit of careful thought, I realised why. The HL7 protocol properties were completely missing from the port declaration in the Services section.  It’s easy to fix this, using the context menu commands:

Then edit the properties in the property grids. Of course, in the JavaCAPS product the wizards prompt you for these properties and create the related WSDL bits behind the scenes.  I don’t like depending on wizards. Fortunately the NetBeans tooling gives you just enough convenient UI to hide the underlying cruft, but also lets you work at the XML / source level and see what’s going on down there.

That’s probably enough for this post.  There’s so much more to write but I need to knock it into shape before I publish.