[binarycloud-dev] asynchronous queuing

[Kristian H. <kri...@ge...>]

Hi,

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