You can add a custom work item control. A work item control for TSWA is a ASP.NET web control. You can add whatever logic when the control is loaded. For more information about custom work item control, please refer to the documents and samples in the SDK folder in the TSWA installation path.
When a work item is changed and saved, TFS will rise a WorkItemChangedEvent. You can handle this event in a web service. Please refer to Integrating a Web Service Notification Customer for more information.
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