Overview of Synchronization with Third-Party Clients
Applies to: SharePoint Foundation 2010
Third-party clients may need to synchronize with SharePoint Foundation lists. In the past this was accomplished by using the GetListItems(String, String, XmlNode, XmlNode, String, XmlNode, String) method. which downloads the entire list. However, it is much more efficient to download only those items that have changed since the last synchronization occurred.
The new GetListItemChangesSinceToken(String, String, XmlNode, XmlNode, String, XmlNode, String, XmlNode) method, introduced in downloads only those items that have changed since the last synchronization, which makes synchronization a much more efficient process.
Sending a GetListItemChangesSinceToken request without including a token returns the list schema, the full list contents, and a token. This token represents the moment when those changes were requested. By including this token the next time you call GetListItemChangesSinceToken, the server returns only those changes that have occurred since the token was generated.
Some changes, such as a change in the list schema itself, are so important that a complete download is necessary. In this case, GetListItemChangesSinceToken returns the entire list schema, the full list contents, and a token.