RE: Remote data access

>> From: Bartell, Aaron L. (TC)
>> 
>> When a request comes into the "mother" I would
>> evaluate if the data they are requesting resides on the "mother" or if 
I
>> need to go to one of the remote "children" iSeries machines.
>
>Is the code the same on the mother as on the children?  That is, would
>each be processing roughly the same kind of request?  If so, you might
>want to consider data queues.  Your "router" on the mother would simply
>send a request to the appropriate data queue, which would be processed
>by a server program.  The router would wait for the response and then
>format it and send it back to the requester.
>
>Why is this a good architecture?  Because on the iSeries you can create
>something called a "remote data queue".  With this, an iSeries in
>Timbuktu can read from a data queue on your machine just as if it were
>local.  That way, you write the code once to handle a data queue
>request, and distribute that code to all your nodes.  You set up one
>data queue locally for "mother" requests, and one for each child.  The
>children each attach to their respective remote queues.  Then it's
>simply a matter of pushing the request onto the correct queue.  Not only
>that, if for some reason you lose connection, the requests stay queued
>until the connection is re-established.
>
>This is the sort of thing the iSeries is really good at.
>
>Joe

Yes, this is quite reliable and reasonably fast. Best of all the Java 
toolkit directly supports it. One caveat is to agree up front on which 
process is going to manage the queue. Does the "mother" clean up after her 
"children", or does the child clean up its own messages? What do you do 
when the child doesn't get there messages for a while? None of these are 
serious issues, they just have to be thought out and managed ahead of 
time. I have seen a similar approach used with a client/server product 
where there was a many-to-many relationship between the servers and 
clients. It worked fairly well.

_________________________________________________________________
Jeff Furgal / MIMIX User Interface Product Architect / Lakeview Technology

furgalj@xxxxxxxxxxxxxxxx / 630-282-8360

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