Tuesday, 25 October 2011

Moving beyond the 32k CFB limit

Gen r8 IE2 increases the Common Format Buffer (CFB) limit from 32k to 16M.

The increase in the CFB limit is available for C generated applications on Windows and UNIX, but not in this release for z/OS, and hence we will not be able to take advantage of this for our products until z/OS support is available for CICS and IMS COBOL servers. It must be the top ranked enhancement request for CA Gen for the past 20+ years, so it is great to see this finally make it into the product.

Previous posts have discussed strategies for coping with the 32k view size limit, and our experiences with a Web View interface has been that it is a good idea for web applications to fetch and display small pages of data rather than trying to bring back a huge results set into a group view. The 32k limit therefore can be a good thing because it provides a limit on the amount of data returned in a single server call.

With the new limit, a developer could massively increase the data returned by a server to ~16M, which might be a good thing if the application did this anyway with repeated server calls, but a bad thing if the user was previously responsible for paging through the data and using filter/selection fields to limit the number of rows displayed, but they can now display thousands of rows without needing to worry about the filters.

Thinking about the impact on our own products (which are developed with Gen), there are several servers that would be much simpler with a larger export view size, so once z/OS support is available, we will take advantage of the larger view sizes to simplify the code and improve performance.

No comments: