Publishing workflow as an ASP.NET Web Service.

 

The workflows developed using windows workflow foundation can be published as a web service. To publish a workflow as a web service, we are provided with two activities. WebServiceInput and WebServiceOutput activity.

 

To create a workflow to be published as a web service do the following

 

Create a new Empty Workflow Project.

 

Add a new interface class to the project which would be used by our WebServiceInput activity.

 

Suppose this is our interface class.

 

interface IAddInterface

                {

        int AddNumber(int firstNumber, int secondNumber);

                }

 

Now right click on the project and add a new Sequential Workflow.

 

Now drag and drop three activities. First WebServiceInput, Code and WebServiceOutput.

 

For webServiceInputActivity1 specify following properties.

 

InterfaceType –IAddInterface.

MethodName–  AddNumber

 

As soon as method is added we’ll see two new properties added over there one for each parameter specified in the interface method.

i.e. firstNumber and secondNumber.

 

Create two variables to bind with them and one more variable to hold the result.

 

  public int intFirstNumber;

  public int intSecondNumber;

  public int total;

 

 

Specify intFirstNumber, intSecondNumber for firstNumber and secondNumber property of webServiceInputActivity1.

 

Finally set IsActivating as true;

 

 

Now right click code activity and select generate handlers to create a handler method and specify the following code for it

 

private void codeActivity1_ExecuteCode(object sender, EventArgs e)

        {

            total = intFirstNumber + intSecondNumber;

        }

 

Now select webServiceOutputActivity1 and set its properties as following

 

InputActivityName = webServiceInputActivity1

 

ReturnValue = Activity=AddWebServiceWorkflow, Path=total (i.e. to total variable)

 

That’s it now we want to publish it as workflow.

 

For this right click the project and Select Publish as a web servcie option.

 

 

This would create a new webservice which would be named as worklflowProjectName.worfklowMethodName_WebService.asmx.

 

Now we could use it just like any other web service created using ASP.NET.

 

WebServiceInputActivity recieves input from the client using the webservice. It can be  associated with single web service method defined inside the interface. The WebServiceInputActivity can be followed by the set of activities which could be built in or custom activity. If the response has to sent back to the calling client than we need to make use of WebServiceOutputActivity.