What is Command level in MQ Series?

In Websphere MQ s开发者_StackOverflow中文版eries , command level for a queue manager is 701. What does it actually specify ?

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WebSphere products use a "[version].[release].[modification].[Fix Pack]" naming convention. For example 7.0.1.6 is the current release specified down to the Fix Pack level.

• Fix packs are limited to bug fixes and very limited non-disruptive functionality enhancements.
• Modifications can include functionality enhancements but no API changes. For example the Multi-Instance Queue Manager was introduced in 7.0.1.
• Releases may introduce significant new function and limited API changes but are highly forward and backward compatible withing the same version.
• Versions encapsulate a core set of functionality. Changes at this level may sacrifice some backward compatibility in trade for significant new functionality. For example, WMQ Pub/Sub was moved from Message Broker to base MQ in the V7 release.

Since administrative functionality does not change in Fix Packs but may change at the Modification level, compatibility with administrative tools is based on the queue manager's Command Level.

There is an old but still useful TechNote which described this when the numbering conventions were adopted for WMQ.

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It displays the major version number of WMQ - e.g. 530,600,700,701. Despite being 'only' a .0.1 increment, WMQ 7.0.1 gets a new major version number due to a number of internal changes (e.g. multi-instance QMs), although WMQ 6.0.1.x and 6.0.2.x were both CMDLEVEL 600

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Command level, although similar to the V.R.M.F, it not exactly the same thing. The Command level is used to allow configuration applications to know what commands (and attributes within those commands) will be understood by the command server.

The first thing any configuration application should do is discover the PLATFORM and CMDLEVEL of the queue manager. Then that application can determine which commands/attributes it would be acceptable to send to that queue manager.

It is possible that CMDLEVEL could be increased in the service stream. Then the V.R.M.F. would not necessarily match the CMDLEVEL. This would happen if some new external attributes were added in the service stream, so queue managers without that patch would not understand them, but queue managers with the patch would. How does an application determine what to send? Well, the CMDLEVEL would determine that and so would have to be upped by the patch.