Curbstone uses Data Queues extensively within our software, and as the primary component for our native API.

Carsten Flensburg brings us up to date on the latest NEW command and attributes of this handy, inter-program communications device.

APIs by Example: New Data Queue Attributes and New Data Queue Command

Carsten Flensburg  |  System iNetwork Programming Tips Newsletter

I use data queues for many purposes and in many mission-critical applications, so whenever IBM announces additions and changes to data queues, I pay attention. With release 6.1, two new data queue attributes were added, and one new data queue API was introduced. The new Change Data Queue (QMHQCDQ) API was partially prompted by the Enforce data queue locks attribute added, because the QMHQCDQ API is currently the only available option when it comes to setting this attribute; you cannot specify it when you create a data queue. I cover more about the Enforce data queue locks attribute later in this article.

The QMHQCDQ API currently supports changing one more data queue attribute, the Automatic reclaim attribute defining whether the allocated storage of the data queue should be reclaimed whenever the last entry in the data queue is removed. This attribute is, however, also available when you create a data queue, but you now have the option of changing it, without having to re-create the data queue. The second attribute added to data queues at release 6.1 is a timestamp registering the point in time the data queue last had its storage automatically reclaimed. These new data queue features inspired me to make corresponding improvements to my previously published data queue commands as well as create the new Change Data Queue (CHGDTAQ) CL command.


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APIs by Example: Data Queue APIs and CL Commands