Using the persistence service in a WCF 3.5 hosted workflow

 

Using the persistence service in a WCF 3.5 hosted workflow   

 

By Serge Luca

MVP Windows Workflow Foundation

This morning a  colleague at U2U asked me how to use the persistence service in a workflow hosted in WCF (.Net 3.5 and Visual Studio 2008).

I’ve created  a quick (and dirty, sorry) step by step tutorial on how to achieve it.

Click here to download the code.

1.Start Visual Studio 2008 and create a new Sequential Workflow Service Library project ; call it WFServiceLibrary.

A workflow with a WF-WCF 3.5 Receive activity linked to the GetData method of a IWorkflow interface will be generated:

 

2.Drag and drop a code activity into the Receive activity and set the ReturnValue to a funny string

3.Create a WCF host for the workflow by generating a Console project

…and add the following references:

 

And don’t forget to add a reference to the WFServiceLibrary as well…

4.In the Host project,..host the workflow and don’t forget to create the persistence database with the scripts provided with the .Net framework :

The second parameter of the persistence service (unloadOnIdle) is set to true, which means the workflow will be persisted by the workflow runtime when it is idle; add a delay activity after the Receive activity to make it idle:

Set its timeout duration to 30 secs.

5.Let’s create the client application by adding a Console application to the solution:

Don’t forget to reference the following .Net assemblies and the library project (just to get the interface definition: I told you it was quick and dirty)

Implement the client-side code in the Main() function :

6.Start the Host (if your run it Vista, I strongly suggest that you start it with admin privileges):

7.Start the client:

Ok, the communication works…

8.Check the persistence database (InstanceState table):

yes the workflow is persisted!!! After 30 seconds, it will be removed from the database.

Click here to download the code.

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