Question

I am new to both Silverlight and WF (both 4.0 version), i was wondering if we can integrate WF4.0 with Silverlight 4.0 in such a way that, when we click on some button in sliverlight UI the workflow should be executed and the output from the final activity of the workflow is displayed in the Silverlight screen. If it can be done then please provide me with some link or any tutorial where i can learn about this and start implementing.

Thanks in advance.

Answer 1

In WF 4.0 you can have workflows started (or progressed) by WCF endpoints. Therefore, if you can call the WCF endpoint from your Silverlight application you should be able to do this quite easily. Lots of information on Microsoft’s WF Developer Centre.

Assuming you are using Visual Studio 2010, you can get up and running with a very simple Silverlight -> WF example very quickly…

1. Create a new project (and new solution) from the ‘WCF Workflow Service Application’ template. The project will be named DeclarativeServiceLibraryX. This should give you a very simple WorkflowService definition using SequentialService that simply receives the request from a client (with a single integer argument) and sends a response (with the same value). This project is created as a web project so includes a Web.config.
2. Create a new Silverlight 4 application. You will be asked if you want to host the Silverlight app in the existing web project (created in step #1). Probably a good idea to say yes.
3. In the Silverlight application, select ‘Add Service Reference…’, then ‘Discover/ Services in Solution’. Service1.xamlx will appear as an option, select it and click Ok.
4. VS will then generate a WCF service reference client. You could then add a TextBox & Button to capture some data, create the client and send the service call across the wire to the WCF Workflow Service. This Workflow Service could then be modified as necessary (or use these steps to add a WCF Workflow Service to your own web project).

One area that might be challenging is modifying the WCF service bindings to be compatible with Silverlight; perhaps create a Silverlight-compatible WCF service in your server-side project first, then create a WF WCF endpoint and look at the generated code & config to see how to put things together.

The MSDN Endpoint blog is also a useful resource for learning more about WF and WCF (especially with the new style lightweight REST-style ‘WCF Web HTTP’ bindings, which might be more suitable for consumption by a Silverlight client.

I am assuming that you don’t want to host the workflow inside the Silverlight app itself, as WF is a full .Net framework component rather than being Silverlight compatible. I’m sure you could write your own lightweight workflow framework that runs inside Silverlight, but given workflow is generally a multi-user, server-side concern this probably wouldn’t be very useful concern.