How to Utilize ETag Capabilities to Build Conflict Resolution Techniques

This section gives an overview of how you can use the E-Tag capabilities in GWM add-in to resolve conflict of data on the server.

Data from a server is accessible to multiple users at the same time. Data conflict occurs when a user tries to update an old data which has already been updated by another user.

The services which handle such conflicts returns an HTTP response of 412 or DataConflict status, when requested to update the data. The services handle such conflicts by a token called the E-Tag. This E-Tag is updated everytime a CUD operation or action is performed on the record.

When you perform Create, Update or Delete (CUD) operation on the data, the GWM add-in will send an HTTP request to the server, to check for the E-Tag.

Note E-Tag functionality is automatically supported (that is, no custom code required) in the GWM Excel add-in template that you generate in Visual Studio, and in the SAP supplied GWM Excel add-in, if the OData service bound to the worksheet, has the E-Tag functionality. E-Tag handling is not supported in any GWM Outlook add-in template that you generate.

If the E-Tag in the request matches with that of the server, the operation will be performed successfully and the server will respond based on the operation result.

If the E-Tag in the request does not match the E-Tag in the server, the server responds with an HTTP response status code of 412. This depicts that there is a conflict in the data which the user is sending and the one in server.

GWM handles such confllicts as follows:

In order to ensure support for E-Tag capabilities in the Microsoft Excel add-in template that you generate in Visual Studio, and in the Microsoft Excel add-in supplied by SAP, make sure that you implement the SAP Notes: 1758035 Information published on SAP site , and 1891024 .