techno.blog("Dion")

Let me walk through a fun time we have had, working with third party integration. The party that we were integrating with has a Web services API that we can talk too, to get what we need done.

Working with Generated Proxies

We were handed a set of pregenerated proxies, in Java code, that we could use to talk to their system. Man, these pregenerated beasts are ugly! You end up working with a Foo, FooImpl, FooResult, Foo_Stub, Foo_KitchenSink, and a million other classes.

So, you quickly try to get a facade in place to make it bearable for any other poor sod behind you.

Lovely error messages

Some of the functionality was working nicely, and then suddenly some of it stopped working. ERROR. Time to look through and see what the problem is… but there was no error information. Not even SOAP Faults that had any information. Nothing. null.

After floundering through the documentation (which is never up to date, or informative), and trying out a bunch of solutions (trial and error… what a great approach), you end up punting to the third party vendor.

The Wrong Proxy

At this point, we find out that a new version of the service is deployed, and we had the wrong proxies. We are then given a new set of Axis proxies. Unfortunately, noone knows which version of Axis. So, you sit there with maven, changing the line with the various version.

Oops, says “no field RPC” guess it isn’t this version. Next!

Finally the right version magic is found between the jars. Some are so special they aren’t on ibiblio, so you need to put them up in your own Maven repository. I know, I know. If you are an ant guy you would just throw it in lib/ and laugh at the poor people that go through the same pain as you.

foo.setBar(null)

Now you are cooking with gas. You have the right libs in place, and you are able to get real results back from the Web service. Then it starts to go wrong again, and the null errors come back.

Bizarrely, you find out that by doing some set methods, even to null, it fixes things. What black magic!

You also learn to CLONE objects when you use them.

So, instead of:

Foo f = Foo.createWithBar(x, y);

e1 = f;
e2 = f;

…

you:

Foo f = Foo.createWithBar(x, y);

e1 = f.clone();
e2 = f.clone();

…

Now it all works again.

Using WSDL

You could, of course, try to just go off of the WSDL, but there were problems with that too. This is why the service company hands you proxies to use instead. They have seen too many interop problems.

Message Versioning and RPC

Doesn’t this smell a lot of RPC which is very coupled? In some ways it is more painful, as not only are you coupled to the proxy jars, but you are hoping that the runtime keeps working!

Ted would cry at this, as it isn’t message oriented at all. In fact, with the service ‘upgrade’ they didn’t even do so in a way to keep backwards compatibility!

Ah, the pleasure of Web services. But now we have a SOA so that is good ;)