Re: [binarycloud-dev] asynchronous queuing

[Alex B. <en...@tu...>]

hi kristian,

Much of the capability you describe below exists in the EntityManager... of
course you would have no way of knowing that given that the spec for it is a
little anemic :)

As far as complex tasks in queues, this is of course a big issue in php
given that it's part of a forking webserver process.

I think the best way to do things are with "cgi" style hooks and cron. There
are many other approaches, but that's solid and it's proven elsewhere.

_alex


> I've been lurking for a while, just thought i'd throw in something I've
> learnt from experience to think about.
> 
> If you are looking at using xmlrpc or other API to interface with systems
> then you should really look at transaction queues / managers.
> 
> For instance, say you need to hit three different systems - pull data from
> the first system,  update data in the second system with the data you just
> grabbed and fire an unrelated event to the third system. Sounds easy enough
> right? What happens if each of these systems take 15 seconds to respond? You
> now have the user waiting 45 seconds for a response - they'll probably hit
> refresh and kick off a second transaction, corrupting your data.
> 
> You can improve the response times by parallelizing the requests, bundle the
> first two requests into a transaction and rund the third request
> concurrently - the response time is now 30 seconds.
> 
> Now suppose that the user won't be looking at the results, maybe they just
> wanted to synchronise the systems and get back to using the site. The
> response isn't relevent to the task the user is performing. A further
> optimisation would be a fire and forget system. Example, put the request on
> a queue and get an immediate response confirming the request. When the
> transaction is complete, a callback could be used to return success or
> failure, and in the event of failure a rollback could be attempted. The work
> is still done and the user can go about their business without long waits.
> 
> Of course the implementation of something like this is where the fun starts,
> it really stretches PHP but is possible I think.
> 
> Kristian
> 
> 
> 
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alex black, ceo
en...@tu...

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