RE: This is a software design question - ILE related

["Nathan M. Andelin" <nathanma@xxxxxxxxx>]

Chris,

Thanks for your perspective.  I've spent a good part of the day reviewing
IBM manuals dealing with ILE and Data Management and have not come to any
conclusion, yet.

If you create a "server" to return data through a queue, you run into one
challenge - you must ensure the correct data is returned to the correct
user.  If you use only two queues (request queue + response queue) you must
somehow synchronize the requesting procedure to only one concurrent job.
You don't want to run into a case where one job puts a request on a queue
and a different job retrieves the response.

One technique I've used in the past is to have a single request queue for
the server, but a unique response queue for each client.  When a client
makes a request, it also tells the server which queue to respond to.

But, then I begin to wonder whether having all those separate queues and
calls to QSNDDTAQ and QRCVDTAQ is any more efficient than multiple open data
paths managed by the OS.

Maybe the new "Thread" support in V4R4 ILE RPG could take care of the
synchronization problem?

Any more insights you can offer?

Thanks.

Nathan M. Andelin


<snip  - from Chris Bipes>

Well thousands of people having the same open data path that would be added
to each program that is bound to the module is a waste of resources.  But
then if you do not have enough servers running to process all the data queue
request, the system will fall behind.  We use the data queue approach for
similar type of request and have a quick time stamp check, if on the queue
for more than xx seconds, start another server after completing the current
request.   If a server times out, we use 60 seconds, more that xx number of
times, it ends.  We use a data area to track how many are currently running,
min number to be running and max number allowed.

I prefer the data queue request idea.  Never thought about it for zip code
lookups.  We also have other files that are widely used for lookup of
values.  Since I have to re-do our current zip code stuff,  I am going to
try the data queue server approach.

Good luck and let me know what direction you go and how it works.



<end snip>


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