"multiple schemas match the message type"may be caused by web services

I was stuck recently with what seemed like a pair of contradictory errors.

I had an application deployed which was exposed as a web service. To test the application we built a test harness which picked up a flat file and called the web service for us and then dumped the result on the file system to see the result.

This testing system worked fine until I needed to use that same deployed schema to do some additional messaging. I wanted to route a message via a receive port and have a send port subscribe to it, then map the message to a new format and deliver it to a destination. Pretty simple, right?

Well, no. When I have my project deployed I got the following error when routing:

There was a failure executing the receive pipeline: "Microsoft.BizTalk.DefaultPipelines.XMLReceive" Source: "XML disassembler" Receive Location: " D:\dat\FileReceive\RoundTrip\*.xml Reason: Cannot locate document specification as multiple schemas match the message type "http://BO.Get.EV2#Method".

That error left me scratching my head. It means I probably have the schema deployed twice, right? I didn't, so I thought. When I undeployed the application the messaging engine could no longer match my message type:

There was a failure executing the receive pipeline: "Microsoft.BizTalk.DefaultPipelines.XMLReceive" Source: "XML disassembler" Receive Location: "D:\dat\FileReceive\RoundTrip\*.xml"
Reason: Finding document specification by message type "http://BO.Get.EV2#Method" failed. Verify that the schema is deployed properly.

When I deployed the project with the schemas, everything suddenly worked fine. That means that, somewhere, the schema was again deployed.

So I looked thru the BizTalk Server Assemblies viewer and discovered that the web reference which existed in my test harness was the culprit. The messaging engine recognized the web reference as a second deployment of my schema. This was technically accurate but rather frustrating to find. I've seen so many of these errors posted on the newsgroups that I thought I'd mention this as a possible cause.

If you are using test harnesses coupled with web services be aware that your schema is actually deployed twice.