December 2007 - Posts

WCF and interoperability
Sunday, December 16, 2007 9:04 PM

I was trying to create an endpoint using WCF that was to look almost identical to an existing endpoint hat was created using some java tools (we were creating a new .Net app and had to mimic some older endpoints).The endpoint seemed ok at first glance according to the WSDL so I generated a client from it using the SVCUTIL.EXE tool and was going to use the interface from that to base my new service off.

I performed the service generation and all looked initially ok. I thought I would regenerate the proxies based off my newly created service just to make sure everything looked right, but my newly generated proxies had no methods at all.

Now to cut a long story short, I found a post here that mentions an interoperability issue with WCF and Java based services. Apparently, some Java services can generate an entry in the WSDL that either contains a blank soapAction attribute or none at all.

<operation name="someOperation">
  <soap:operation soapAction="">
...
</operation>

More information in this can be found here.

What this does though is cause SVCUTIL.EXE to generate a ServiceContract with an attribute like this:

System.ServiceModel.OperationContractAttribute(Ation = "", ReplyAction = "*")]

However, what it needs to be is something like this:

[System.ServiceModel.OperationContractAttribute()]

and then life will be good and you will get all your expected methods. So I simply took a copy of the generated interface code, and changed to suit. Since SVCUTIL.EXE is a client side tool, its not like i will be regenerating this all the time, I merely used it as a shortcut to get the interface in as quick a time as possible. This technical hiccup caused me to use more time than anticipated, but its a pretty easy fix.

WCF Beta Exam
Sunday, December 2, 2007 8:17 PM

I took the opportunity to sit the WCF Beta exam a few days ago and I must say, it was very hard. Being beta, I don't find out the results until about 8 weeks later, but I reckon I didn't fare too well.

I did book the test a little impulsively, however I saw the opportunity to do it, and only had a free day to do the test that was a few days later than when I booked it, so my preparation time was very small.

Having said that, I still think it was a hard exam. There were a wide variety of questions there and the preparation guide listed here doesn't really do the broad range of topics justice as there were still items/topic in the exam that were not listed in the prep guide.

If I do the exam when its released, then I think I'll prepare for the exam for around 2 months before sitting it again. Note that I have worked with WCF a reasonable amount and have also taken Juval Lowy's WCF Masterclass course but I would still allocate around 2 months prep time on top of that.

One of the things that did irritate me about the test (and its not specific to this test either) is when you are tested on your knowledge of things like enum values. One of the questions had code samples that differed only in the value of an enum being specified. Now admittedly, if I had worked a lot with the aspect of WCF, I would probably know it, however questions like these assume you dont have the services of a compiler at hand. Even if I didn't know it, practically, it would take a around 5 seconds to see this error when compiling and fix it, and still achieve a quality WCF implementation. I just don't see those types of questions of having any real practical value.

Anyway, if your thinking of sitting the WCF beta exam, or waiting for its proper release. Allocate a  decent amount of preparation time, as it is quite hard.

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