Configuration based ESB

I think that anyone who read my previous posts can see that I work allot with ESBs – the blog posts were mostly dedicated to IBM, but I work with OSB, JBossESB and some other solutions as well.

I am amazed at just how much work customers invest in ESB development – they build an architecture, build a development team – and usually, 99% of the work they do – is the same across all organizations.

Because everybody are using ESB in the same way – to enforce web services policies – usually security, but also validation, version management, monitoring and a bit more.

So – what do all these off-the-shelf products give us? Not enough.

I believe that a new generation of ESB is in order – one that will not require coding. The ESB should contain a single point of entry for all services in the organization, all will follow a configured validation and enrichment path, and at the end will be directed to the actual service. No coding, no development team – just simple configuration. Should definitely suffice most customers.

I have a few ideas on an architecture of such a thing, and Aluna even has a small product based on open source technologies, that runs with both .net and Java clients.

But that is another story.

WebServices Reliable Messaging

A customer of mine asked me to build a POC of using WS-RM with CXF, C# and Oracle Service Bus. Against my better judgement – I said yes. I know it doesn’t work – but I’m always up to the challenge.

Turns out documentation is shitty at best. Vendors provide a one-page demo, using messaging infra or embedded HTTP servers – no web containers or web servers.

So – I have decided to start with .net and CXF and leave the OSB for later.

The pain is installing VS2010 Beta 2 over my machine which had VS2010 Beta 1 – a version that was deleted a couple of month ago.

You can’t install VS2010B2 on a B1 computer – you must do a reinstall of B1, then uninstall it, then install B2.

Bloody nightmare.

WebSphere Process Server – skipping steps in the process

A customer of mine has decided to build an application that can monitor his processes, instead of the regular WPS supplied tool.

His main concern was skipping steps. Turns out that when a process has executed a specific activity, and this activity is in a special position (like user task) – an outside application can cause a skip in the process.

I have developed a short demo for this, and I’m enclosing the main method here. Just make sure to disable the process security before running it – or you’ll get a non authorized exception…

// Connect to the server

Properties props = new Properties();

props.put(Context.PROVIDER_URL, “iiop://localhost:2811”);

javax.naming.InitialContext ctx = new javax.naming.InitialContext(props);

// Lookup the BusinessFlowManager. If you get casting exception – read the InfoCenter – you need to add some JARs to your code – it’s WPS/ProcessChoreographer/client/bpe137650.jar

Object lookupResult = ctx.lookup(“com/ibm/bpe/api/BusinessFlowManagerHome”);

BusinessFlowManagerHome processHome = (BusinessFlowManagerHome) PortableRemoteObject

.narrow(lookupResult, BusinessFlowManagerHome.class);

BusinessFlowManager bfm = processHome.create();

// Replace with any process id

ProcessInstanceData pid = bfm.getProcessInstance(“_PI:90030124.f71386d4.dbed54f5.5d84025c”);

// Replace with any activity name

ActivityInstanceData aid = bfm.getActivityInstance(pid.getID(),”Wait”);

// Skip to the specific activity

bfm.skipAndJump(aid.getID(), “TargetActivity”);

AspectJ 1.6 with runtime weaving and WPS 6.2

Well, I haven’t blogged in ages, and it’s not because I lacked things to share…

Anyway, almost all of my WPS customers are looking for some level of polymorphism (or process templating) and AOP. For the first – I currently have no solution. For the second – here comes…

1. Download AspectJ 1.6.2.
2. Since it’s been a long time since I worked with AspectJ, I wrote a small program in Eclipse. I just made sure that it used the WPS JDK – to make sure the -javaagent flag works. It does. However, you can’t use it when your eclipse works with a Sun JDK. So – add a -vm to your eclipse.ini file. (See here for details: http://wiki.eclipse.org/Eclipse.ini
3. Now, I opened a new WID module, wrote a short process.
4. I also created a small Java Project, which will create a JAR in the WAS/lib directory. It will include my aspects and the aop.xml file (under the META-INF directory)
5. I started my WPS server, and put the -javaagent flag in the startup options. WAIT!!! Since WPS security is enabled by default, and the aspectJ weaver is located outside the WPS libraries – java security policy won’t let it load – and you can’t start your server!!! Copy the jars into the WPS lib directory. Just make sure you don’t override existing files (aspectj.jar should be in WPS/lib – just rename it to something that doesn’t end with JAR)
6. That should be it – the aspects now work. However, how do we tie them to the process itself?
7. It seems that the way WPS works is that for every BPEL activity there is a class in the com.ibm.bpe.engine package, and the doActivate method is called. So our pointcut will need to look like this – @Before(“call(void com.ibm.bpe.engine.BpelActivityKind*.*(..))”) – this should also explain why we put the aspect in the JAR in the WAS/lib directory – it should be in the correct class-loader level.
8. Well the only thing missing is the actual pointcut – but it’s too late for that – will publish it tomorrow morning… Don’t hold it against me. I will also post the required code to get which Activity we are on. Quite cool…

WebSphere ESB and EJBs

My next post will probably be a book review – I was asked to review a new book on WAS 7.0 administration. Cool. Hopefully I’ll be able to read it in the next couple of days (did I ever mention I was a quick reader?)

In the meantime, I want to publish my findings on the use of EJBs in WebSphere ESB.

A customer of mine is using WebSphere ESB. For services, it developed EJBs (stateless, of course, but still – version 2.0).

The mediation module has imports for the EJBs.

This turns out to be a very bad architectural decision (I arrived to the project after this decision was taken 🙂 ) , and right now they are rewriting everything, to drop EJBs and use SCA Java components.

Why?

1. SCA Java components are actual EJBs, so why have an EJB call an EJB? Not a smart move, performance wise.
2. Mediation Module (6.1) EJB support is lousy. It fails generating good mapping between the Java bean parameters and Data objects. So my customer resorted into sending Strings to the EJBs, and then parsing them, at the EJB level, to POJOs, using XMLBeans. This is insane – and shouldn’t be done.

So what is the current (working!) recommendation?

Use SCA Java components, in the same module, or other modules, depending on your component visibility and deployment needs.

Inside the Java component, use a mapper to map the DataObject object into real Java POJO. and then pass it to your business logic, which is implemented in regular Java Classes.

The mapper is really easy to write:

1. Use JAXB or XMLBeans to generate mapping between the DataObject XSD and a Java class.

2. Write a method that has the following signature:

public static Object mapper(DataObject do, Class clz)

3. Use reflection on the clz – create a new instance of it, and for every field decide:

3.1 If its a primitive – transform it.

3.2 If its a Java Class – call yourself in recurssion

3.3 If its an array – run over all elements

It works fine, great performance, and the development barrier was lowered by more than a few inches.

Hope it serves someone well.

WebSphere ESB Invalid Content Length

Well, turns out I was mistaken in my previous post. Invalid Content Length can occur when using MTOM in .net C# clients with WebSphere ESB, but that was not the case in our customer.

Invalid Content Length appeared when the client closes the socket before sending the entire request. This can happen when the process is halted during send time. WESB will sysout Invalid Content Length, but you can usually ignore it.

However, we still faced a problem with very large service calls (over 1MB in size – only XML, no attachments). Turns out that our synchronization code was messed up, and for some reason – our cache was not correctly initialized, and so we received allot of NPE (NullPointerExceptions).

So – we synched our cache, and voilla – all works.

That teaches me to blog before I see everything working in my own eyes.

One last important issue. Sending large service calls can take time. Allot of time. And so, each C# client has a Timeout property, that sets that Timeout for the service call, in milliseconds. Use it well, since you are very likely to get a Timeout exception before you get the web service response.