Why is vsam used

The records in VSAM can be either variable or fixed length. By: Justin Stoltzfus Contributor, Reviewer. By: Satish Balakrishnan. Dictionary Dictionary Term of the Day. Gorilla Glass. Techopedia Terms. Connect with us. Sign up. For ESDS, an alternate index or a path for an alternate index must be defined. Relative record datasets RRDS are not allowed, since they do not contain any key fields descriptors.

The GET statement does not initiate a processing loop. The values are read directly from the VSAM index and are returned in ascending or descending value sequence. The records can be retrieved in the value sequence ascending or descending of a descriptor key field.

The READ sequence initiates a processing loop. A descriptor can be used for sequence control. A descriptor within a periodic group cannot be used. A subdescriptor or superdescriptor can be used for sequence control, too. The properties of the server process, such as connection pooling requirements, are defined by a workspace definition within the daemon. The server process includes an instance of the application engine, which converts the XML format into native structures understandable by VSAM and passes the converted XML to the back-end adapter.

The back-end adapter builds an interaction based on the metadata for the back-end adapter stored in the repository and the incoming converted XML, and passes it to the legacy application.

The results of this execution are passed back to the application engine, using the back-end adapter, where these results are converted to XML and passed back to the client. Skip Headers. Description of the illustration xipvs