NoPersistScope Activity

This topic applies to Windows Workflow Foundation 4 (WF4).

This sample shows how to manipulate a non-serializable and disposable state within a workflow. It is important that workflows do not attempt to persist non-serializable state and it is also important for disposable objects to be cleaned up after they are used in workflow.

Demonstrates

NoPersistScope custom activity and designer.

Using the NoPersistZone activity

When the sample workflow runs, a custom activity called CreateTextWriter creates an object of type TextWriter and saves it into a workflow variable. TextWriter is an IDisposable object. This TextWriter, which is configured to write to a file named ‘out.txt’ in the directory in which the sample runs, is used by a WriteLine activity as it echoes any text you type in at the console.

The echo logic runs within a NoPersistScope activity (the code for which is also part of this sample), which prevents the workflow from being persisted. If you type in unload at the console, the host attempts to persist the workflow instance but this operation times out because the workflow remains within a NoPersistScope. The workflow also utilizes a custom activity called Dispose to dispose the TextWriter object when the workflow is finished using it. The Dispose activity is placed within the Finally block of the TryCatch activity in which the TextWriter variable is declared, to ensure that it runs even if an exception should occur during execution of the Try block.

You can type in exit to complete the workflow instance and exit the program.

To run the sample

1. Open the NoPersistZone.sln solution in Visual Studio 2010.

2. To build the solution, press CTRL+SHIFT+B or select Build Solution from the Build menu.

3. Once the build has succeeded, press F5 or select Start Debugging from the Debug menu alternatively, you can press CTRL+F5 or select Start Without Debugging from the Debug menu to run without debugging.

To cleanup (optional)

1. To remove the SQL Instance Store, run Cleanup.cmd.

Note:

The samples may already be installed on your machine. Check for the following (default) directory before continuing. <InstallDrive>:\WF_WCF_Samples If this directory does not exist, go to Windows Communication Foundation (WCF) and Windows Workflow Foundation (WF) Samples for .NET Framework 4 to download all Windows Communication Foundation (WCF) and WF samples. This sample is located in the following directory. <InstallDrive>:\WF_WCF_Samples\WF\Scenario\ActivityLibrary\NoPersistScope