On Thursday, September 4, 2003, at 10:15 PM, gianny DAMOUR wrote:
Dain wrote:It is true that MethodProxy is super fast (I also gave it a try), however - I may be wrong here - the number of hits on the Manageable Objects will not be significant enought to see a true performance improvement.
It really depends on how we implement things. There may be some services that get hit often (especially if you have a monitoring application). Using a MethodProxy is just as easy a using reflections so I will most likely always use it.Thanks for this answer.
I agree: it depends on how we implement things. For instance, a monitoring application could either poll the Manageable Objects or register an AttributeChangeNotification listener to keep its display updated.
My believe is that a monitoring application, which uses a polling mechanism, is not implemented correctly expecially if the Manageable Objects emits notifications. The fact that such applications may have an intrusive impact is "acceptable".
Agree.
Acutally, my real concern was to have a simple implementation in a first stage and then roll-out an attribute cache, if required. Indeed, AFAIK this cache must be keep in sync. In order to keep this cache in sync, the manageable objects MUST emit attribute change notifications, and the cache needs to listen to them. Even if such an implementation could be trivial, it adds a complexity to the solution.
That is not really how caching works; it is simply timed invalidation. When getAttribute is invoked we simply check if the last read is still valid. If it is still valid we return the cached value; otherwise we call the getter directly. It is useful for attributes that never change and for attributes where slightly stale data is okay. For everything else you disable caching.
Attribute change notifications will be handled by the GeronimoMBean directly. If the target changes values internally we won't see those unless the target sends the notification itself using the GeronimoMBeanContext handle, but it will need to distinguish between internal changes and changes from the GeronimoMBean or listeners will see two change notifications.
All of the code is in, so take a look at it.
-dain
/************************* * Dain Sundstrom * Partner * Core Developers Network *************************/
