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AttributeListeners VS BindingListeners

Ricardo Cortes
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Joined: Jan 23, 2002
Posts: 140
I am having some problems understanding the difference in functionality provided by the HttpSessionAttributeListener interface and the HttpSessionBindingListener interface. Does anyone have an easy way of differentiating the roles of the above named interfaces?


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Ricardo Cortes
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Joined: Jan 23, 2002
Posts: 140
Actually, I think I finally figured it out. Correct me if I am wrong. If I have an object aBook of type Book, then HttpSessionAttributeListener will send out a notification when an object has been added, replaced or removed from the session whereas HttpSessionBindingListener will send out a notification (as long as Book implements the HttpSessionBindingListener interface) when aBook has been bound or unbound from the session. Is this a correct?
Brian Glodde
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Joined: Jun 27, 2001
Posts: 171
Ricardo, this is a great question.
The only comment I can add is when you alter a session-level object (add/modify/remove) and the object implements HttpSessionBindingListener, the container calls the valueBound method and then notifies the appropriate HttpSessionAttributeListener(s).
I've also tried writing some sample code to fully understand the distinction, but so far, it hasn't caused the proverbial light to come on.
Ricardo Cortes
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Joined: Jan 23, 2002
Posts: 140
So, in other words, if I want to monitor the adding/removing/replacing of objects to the session I use HttpSessionAttributeListener and I want to monitor changes to a specific object's values then I have that object implement HttpSessionBindingListener?
Ricardo Cortes
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Joined: Jan 23, 2002
Posts: 140
I guess I never realized how good the search function of this messageboard really was...I did some searching and found several posts on the subject, including this one:
http://www.coderanch.com/t/164328/java-Web-Component-SCWCD/certification/difference-HttpSessionBindingListner-HttpSessionAttributeListner
 
It is sorta covered in the JavaRanch Style Guide.
 
subject: AttributeListeners VS BindingListeners
 
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