How to host the Windows Workflow as a Web service(.svc)? - workflow

Question

I am trying to host the windows workflow as a web service, below is the sample workflow that I built and would like to host as a web service(.svc), can you please suggest the required steps?
using System;
using System.ServiceModel.Activities;
using System.Activities;
using System.ServiceModel;
using System.Activities.Statements;
namespace DemoWF
{
public class _25_LeaveRequest
{
public WorkflowService GetInstance()
{
WorkflowService service;
Variable<int> empID = new Variable<int> { Name = "empID" };
Variable<int> requestID = new Variable<int> { Name = "requestID" };
Receive receiveLeaveRequest = new Receive
{
ServiceContractName = "ILeaveRequestService",
OperationName = "ApplyLeave",
CanCreateInstance = true,
Content = new ReceiveParametersContent
{
Parameters ={
{"empID",new OutArgument<int>(empID)}
}
}
};
SendReply replyLeaveRequestID = new SendReply
{
Request = receiveLeaveRequest,
Content = new SendParametersContent
{
Parameters ={
{"requestID",new InArgument<int>(requestID)},
},
},
};
Sequence workflow = new Sequence()
{
Variables = { empID, requestID },
Activities = {
new WriteLine{Text="WF service is starting..."},
receiveLeaveRequest,
new WriteLine{
Text=new InArgument<string>(aec=> "Emp ID="+empID.Get(aec).ToString())
},
new Assign<int>{
Value=new InArgument<int>(5),
To=new OutArgument<int>(requestID)
},
new WriteLine{
Text=new InArgument<string>(aec=> "Request ID="+requestID.Get(aec).ToString())
},
replyLeaveRequestID
},
};
service = new WorkflowService
{
Name = "AddService",
Body = workflow
};
return service;
}
}
Right now, it is self hosted as highlighted below
namespace DemoWF
{
class Program
{
static void Main(string[] args)
{
LeaveRequest();
}
private static void LeaveRequest()
{
_25_LeaveRequest receiveAndReplyWorkflow = new _25_LeaveRequest();
WorkflowService wfService = receiveAndReplyWorkflow.GetInstance();
Uri address = new Uri("http://localhost:8000/WFServices");
WorkflowServiceHost host = new WorkflowServiceHost(wfService, address);
try
{
Console.WriteLine("Opening Service...");
host.Open();
Console.WriteLine("WF service is listening on " + address.ToString() + ", press any key to close");
Console.ReadLine();
}
catch (Exception e)
{
Console.WriteLine("some thing bad happened" + e.StackTrace);
}
finally
{
host.Close();
}
}
}
}

Answer 1

The quickest way would be to create a WCF Workflow Service Application.
You'll get a workflow designer where you can drag and drop the activities you need:
And if you run the project in Visual Studio, you'll get an auto-generated WSDL with your service operation(s):
And also it will bring up Visual Studio's WCF Test Client tool:
You can create a workflow-based service that handles multiple methods by using the Pick Branch activity. Each branch would then have a Receive and Send Reply activity, with the receive activity moved to the trigger section and the send reply activity in the action part.
Each trigger would be for a specific operation on the service. In the following example, I define two operations: MyFirstOperation and MySecondOperation.
Below is what the WCF test client tool will show with multiple operations exposed from the workflow:
Hopefully that gets you started. The topic of standing up workflow-based WCF services can get quite involved. :)