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Yes I know, but then there would two 2 commits for each API call - well I try to go the RabbitMQ way for the next projects ...
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Marten
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James Foster <smalltalk@jgfoster.net> hat am 24.08.2022 10:08 CEST geschrieben:
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</div> That looks very good (and similar to what is done with the GemStone implementation of Seaside).
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On Aug 24, 2022, at 9:48 AM, Marten Feldtmann <<a class="" href="mailto:m@feldtmann.online">m@feldtmann.online</a>> wrote:
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Hello James,
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well one way would be to do:
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Client => Server (sends request)
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Server gets the request
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abortTransaction
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begin Transaction
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<do the stuff to do in gemstone server data structure>
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commtTransaction (if this fails, retry the block>
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begin transaction
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<update the timestamp>
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commitTransaction (if this fails do not care)
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abortTransaction
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Server => Client (send the answer)
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James Foster <<a class="" href="mailto:smalltalk@jgfoster.net">smalltalk@jgfoster.net</a>> hat am 23.08.2022 21:52 CEST geschrieben:
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</div> I interpret you to say that this is an “application” session object that can be updated from several gems. Is there a reason you don’t do an abort before processing the client update?
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On Aug 23, 2022, at 9:37 PM, Marten Feldtmann <<a class="" href="mailto:m@feldtmann.online">m@feldtmann.online</a>> wrote:
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Its a Gemstone/S object, which is created after an application has been connected (logged in) to the server via my application API. This API is the connection from Gemstone/S to all the other clients running around, written in Python, C#, Java or Javascript.
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Each application sends the gop of its "session" with each request ... to the server and there are lots of http topaz based server tasks waiting for requests.
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Under SQL this problem can be solved without any problems - but under Germstone/S this "simple" problem is difficult to solve: it can be reduced to the question - can an object be updated but changes at one specific attribute should not be taken into account when calculating concurrency situation.
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Marten
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James Foster <<a class="" href="mailto:smalltalk@jgfoster.net">smalltalk@jgfoster.net</a>> hat am 23.08.2022 09:45 CEST geschrieben:
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Marten,
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Could you clarify your use of the word “session”? Is this an application session that crosses several Gems or is it a GemStone session (a single Gem)?
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James
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On Aug 23, 2022, at 9:31 AM, Marten Feldtmann via Glass <<a class="" href="mailto:glass@lists.gemtalksystems.com">glass@lists.gemtalksystems.com</a>> wrote:
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I've face a problem for years now using Gemstone/S and I did several attempts to solve this, but I would like to ask, if there is a hidden trick to get rid of concurrency in this case using Gemstone/s.
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Think about a session object holding an attribute with a timestamp - a timestamp, where the last successful commit has been done in this session. Its a rough index about how the session hasn't done anything (regarding the read-only user case).
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This session object is shared in a Javascript ui frontend-application (actually the gop to the session) - and now whenever this ui calls an API function on the server (resulting in a commit), the session object in the server gets updated. But if the UI now opens several windows and would like to do sevral independent stuff with the same session in a concurrency way - you will notice, that the API calls might fail - due to concurrency of updating the same timestamp from different "logical" threads.
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How can this be solved in Gemstone/S ? Retry of the transaction just due to this field might be pretty cost intensive.
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How did I try to solve that in the past ?
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a) I added an update object in a work queue and and independent topaz process worked on that work queue
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In a newer attempt I introduced RabbitMQ in our solutions and use RabbitMQ for holding the information formerly stored in the work queue in Gemstone/S and now the topaz process receives information from RabbitMQ and updates the data in an optimized way. The good thing here is, that I get session updates in an transaction with or without commit.
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Any ideas ?
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_______________________________________________
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Glass mailing list
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<a class="" href="mailto:Glass@lists.gemtalksystems.com">Glass@lists.gemtalksystems.com</a>
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<a class="" href="https://lists.gemtalksystems.com/mailman/listinfo/glass" target="_blank" rel="noopener">https://lists.gemtalksystems.com/mailman/listinfo/glass</a>
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