Re: Data Queues Beginner Question

["Richard B Baird" <rbaird@xxxxxxxxxxxxxxxxxxxxx>]

Justin,

Not really an rpg question, but a classic use of a data queue is as
follows.

Program A performs a specific (maybe complex and maybe lengthy) function.

Programs B, C, D, E, F, and G, all do things that makes the specified
function in program A to be performed, but don't really care to know that
it has been done, and don't need to know any results from the function, and
would just as soon get on with thier own life, safe in the knowlege that
they don't have to perform the functions of program A, but that it will be
done......

instead of calling program A, these other programs will simply add a
'record' to a data queue.

Meanwhile, an autostart job in a subsystem of your choice, has called
program A, when the subsystem was started (or any other method you decide
to use to get the program started).

Program A is a never-ending-job, and does nothing but 'listen' to the
dataqueue, and when it finds an entry, it does it's thing.

There are many other uses for dataqueues, but the main jist of them is a
method of communicating transactions from one place/program/whatever to
another, where you don't need a history of those transactions. (data queue
entries are volotile, once retrieved, they dissappear).

using a data queue wouldn't be a good way of looking up inventory
quantities, but it might be a good way of updating inventory quantities,
provided you don't REQUIRE that the update be done immediately before
continuing (though chances are, in the above scenario, it WILL be done
immediately, but the initiating program doesn't wait for it to be done
before continuing)

clear as mud?

hth

rick