Calling WCF Service with no input parameters in BizTalk Orchestration

Question

I am trying to call an IIS hosted WCF web service that simply returns the current date from a BizTalk orchestration. There are no input parameters to this service.

Please ignore the First Receive_1 and the Last Send_1 shapes as I just used them to get started with this orchestration. My Orchestration looks like:

I used the "Add Generated Items..." wizard to add the generated reference to the web service in the Orchestration. My web service definition looks like:

[ServiceContract]
public interface ICalculator
{
    [OperationContract]
    DateTime GetLastExecutionDate();
}

public class CalculatorService : ICalculator
{

    public DateTime GetLastExecutionDate()
    {
        return DateTime.Now.AddMonths(-6);
    }
}

After I added the generated reference to the BizTalk project, the wizard created a set of ports and Multi Part Messages like below:

I have also created local messages to transport data between these calls like below:

Now, I have read everywhere I could that I will need to construct the InputMessage in order to call a web service with no parameters.

Some forums/website say that I need to simply created a blank ConstructMessage shape with the MessageType of dateRequest Message. While doing so the project doesn't compile and I get the following error message:

And the other suggested item is to do a MessageAssignment for a blank Document. So the MessageAssginment shape in my Orchestration has the following:

xDoc = new System.Xml.XmlDocument();
xDoc.LoadXml("<GetLastExecutionDate/>");
dateRequest.parameters = xDoc;

While this compiles and get's deployed, my BizTalk instance get's suspended with the following exception:

There was a failure executing the send pipeline: "Microsoft.BizTalk.DefaultPipelines.XMLTransmit, Microsoft.BizTalk.DefaultPipelines, Version=3.0.1.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" Source: "XML assembler" Send Port: "REDACTED_1.0.0.0_REDACTED.ExportData_WCFPort_dace989afd9cd9c5" URI: " http://localhost/COMPANYNAME/WCFService/Service.svc " Reason: This Assembler cannot retrieve a document specification using this type: "GetLastExecutionDate".

And the parameter data passed into the service is:

So my question is: How do I call a WCF Service that does not expect any input parameters.

Answer 1

Go to your service request message schema file from within visual studio.

Right click -> Generate Instance.

Grab the XML instance generated and replace all the double quotes with single quotes.

Then paste this into your LoadXml() in your assignment

Answer 2

You use the XMLTransmit pipeline and there could be multiple root causes for it throwing error message

"Reason: This Assembler cannot retrieve a document specification using this type: xxx"

The most likely cause is that you do not have a schema deployed matching the message you are transmitting.

But the good news is that there is no need for the XMLTransmit pipeline in this scenario. Just change the send-pipeline to PassThruTransmit and it will most likely solve at least that problem.

Answer 3

You probably need an XML namespace in the string used in the message assignment shape. I suggest you validate your XML string against the web service schema to make sure it makes a valid message.

You could also use xsd.exe to create .NET classes from your web service schema.

See http://msdn.microsoft.com/en-us/library/aa547985(BTS.20).aspx for a complete list of ways to contruct a message in an orchestration.