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From Rob Davies <>
Subject Re: more topics against more filters - overhead estmation
Date Sun, 06 Jan 2008 19:37:44 GMT
I'll assume all the clients are active at the same time - and that you  
don't require durable subscribers. In which case there will be the  
destination itself - which is a relatively small object and queued  
messages for each subscriber to a destination.
The trade of is one of performance against memory usage. Using filters  
(via selectors - - will  
result in every message being evaluated - which will be moderately  
slower than the look-up for the destination itself.  This can be  
traded against message references held for each subscriber (one per  
destination per client) - as well as the destination object overhead.

Alternatively - you can use wild cards - 
  on the destinations - which is faster than selectors - providing you  
can break your destinations into a suitable hierarchy (this would be  
my choice btw).

If you want your application to remain 100% JMS compliant, use  
selectors - as not every vendor can handle a large number of  
destinations - and wildcards are not always supported - and the syntax  
can change from vendor to vendor.

Hope that helps,



On Jan 6, 2008, at 11:31 AM, breezee wrote:

> Hi,
> I am planning a system which will involve one broker and many  
> clients (about
> 40) that will use it.
> calculating the usage, i will have to hold about 700 topics per  
> client,
> total of 28000.
> That seems pretty large . I am considering making some topics shared  
> for
> different usages, using message filters.
> My question is simple:
> how can I best define the overhead of lots of topics/lots of  
> filters? does
> every new topic keep a live thread, for example? does large amount of
> filters on the same topic wil make te filter non-usable?
> Thanks in advance,
> Amit.
> -- 
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