With both approaches, the payload of the response is reduced but as described, only the first approach is also able to optimize the performance in the back end.

 

Delta Determination at Request Time

Advantages include: Smaller implementation effort is required while providing sufficient delta functionality.

 

Disadvantages include: Delta determination at request time, and potential negative performance impact on the back end, especially for large collections

 

The delta token functionality, based on the delta request log component, uses two database tables to store hash values: /IWBEP/D_QRL_HDR and /IWBEP/D_QRL_ITM. Once this offline functionality is used productively, the size of these tables increases with each request. You can run the following report to clean up outdated entries: /IWBEP/R_CLEAN_UP_QRL. It’s a good idea to schedule a job for this report so that it is executed periodically, for instance on a daily basis.

 

Delta Determination at Modification Time – Syclo Exchange Framework

The Syclo Exchange Framework is provided as ABAP add-ons (former Syclo add-ons). Data in the SAP Business Suite back end is always updated using an SAP update program. This update program is called in various ways using a program, a function module, a class, or an ABAP routine.

 

The Exchange Framework is embedded into these update programs as a listening agent of the standard SAP update process. The framework creates a before and after image of the business object being changed.

 

The exchange table is used to store information on the records that have been created, updated, or deleted. A helper class provided by the framework can be used by Gateway to access exchange tables to enable delta queries.

 

 

The advantages of delta determination at modification time is that the determination is more scalable, and gives more optimized performance.

 

A disadvantage is that this method requires some additional configuration or development.

 

Tombstones

Entries that have been deleted are sent in the response as “tombstones”. Since this concept is only available for the atom publishing protocol, we have implemented tombstones for the OData version 2 protocol only for the ATOM protocol and not for JSON.

 

With OData v4 the delta query protocol becomes part of the OData standard. In addition, JSON will become the default protocol. Tombstones will therefore also be supported with JSON and OData v4.