Update 4.0.3 for Microsoft .NET Framework 4 Windows Workflow Foundation Features

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

Update 4.0.3 for Microsoft .NET Framework 4 is an update that is a set of new features that provides additional functionality for top customer requests and important scenarios. Update 4.0.3 for Microsoft .NET Framework 4 includes new features for Windows Workflow Foundation (WF) as well as new features for other areas of the framework. This topic provides an overview of the new WF features in the update. For an overview of all of the features in the update, including installation and deployment instructions, see Update 4.0.3 for Microsoft .NET Framework 4. For more detailed information on the specific features in the update, including the non-WF features, see Update 4.0.3 for Microsoft .NET Framework 4 – Runtime Update (KB600211).

Support for Running Workflows in Partial Trust

Workflows that use Windows Workflow Foundation 4 (WF4) can run only in fully trusted application domains. This update enables WF to run in partially trusted environments. The scope of the change is enabling the core workflow runtime (execution model, activity and data model, tracking, and serialization) to run in partial trust. To enable this change, some WF assemblies have AllowPartiallyTrustedCallersAttribute (APTCA). For more information about partial trust, see Using Libraries from Partially Trusted Code.


SqlWorkflowInstanceStore and Visual Basic expressions are not supported by this change. Therefore, these features are not available in partial trust.

Enable WF Messaging Activities Across Multiple Hosts

WF4 messaging activities (Send, Receive, ReceiveReply, SendReply, and so on) use WCF to send and receive messages. This update introduces SendReceiveExtension. SendReceiveExtension is a new WF extension that is used by these activities to send or receive messages (or both). The extension has to be provided by the host. If the extension is not present, the WF4 behavior and execution is preserved (no changes to current code path). If the extension is present, the activities call the methods in the extension.

The new extension has methods for each of the steps that are involved in different messaging patterns. The host authors can implement those methods to implement the messaging semantics that they want to use with the existing WF4 programming model.