Workflow Redesign Not Backward Compatible

The Windows Workflow Foundation (WF) 4, part of the .NET Framework 4, is a complete rewrite of the programming framework. WF 4 delivers many improvements, including simplified coding and better performance, but it is not backward compatible with the current version, which is used in several Microsoft products. Organizations with existing WF applications will have to decide between keeping the current WF running alongside the new one or reimplementing code, and organizations considering new projects might want to take advantage of the new version.

WF 4 uses a new API, database schema, and designer tools that are not compatible with WF 3.5 workflows and activities, forcing organizations with existing WF applications to choose one of the following strategies:

Continue running and developing on WF 3.5. The WF 3.5 API is contained within the .NET Framework 4, so existing applications will continue to run after upgrading to .NET 4. This strategy eliminates migration costs and leverages existing developer skills for organizations that are willing to forego the benefits offered by the improvements in WF 4. Also, organizations with applications that have dependencies on Microsoft products or third-party products that in turn require WF 3.5 may need to choose this option.