Inside Microsoft® Windows® SharePoint® Services 3.0

Event Receivers

Event Receivers represent a developer-extensibility mechanism that can be used to add behaviors to various elements such as lists and list items. An event receiver is a class that contains one or more methods known as event handlers that are executed automatically by WSS in response to events such as a user adding a column to a list or a user deleting a list item. The event handlers are typically written to perform data validation, to ensure data integrity, or to kick off custom business processing.

Events supported by WSS can be separated into two categories: before events and after events. A before event fires before an action has been completed. For example, WSS fires a Field-Adding event when a user attempts to add a new column ...