[erlang-questions] OTP Design Pattern Question/gen_server with different parameters?
Tue Mar 10 18:51:06 CET 2009
I wonder if you are throwing too many processes and servers at the problem.
Can the solution be implemented by plain old functions within a single
2009/3/10 Jonathan Palley <jpalley@REDACTED>
> All - I've got this running in straight Erlang, but trying to understand
> how to apply to the OTP pattern.
> Wondering the best practice for a system like this:
> event comes in (external source) -> various event handlers get sent the
> event based on the event type. -> these event handlers will filter the event
> to determine if they should send it on (via an http request).
> The trick is this: there is an interface to add and delete event handlers
> with a filter.
> In straight erlang I:
> - Created a new process for each handler. The handler would be init with
> the filters.
> - A central event processor stored the PID of each handler and the event
> type it was subscribed to. As an event would come in it would re-broadcast
> to the different handlers.
> - Each handler would then use its custom filter to determine whether to
> send it on.
> Now, I would like all the robustness that comes with OTP. Perhaps I am
> approaching this incorrectly, but what I can't figure out is:
> - If I start multiple instances of gen_event (with different filters each)
> and add it to a supervisor tree, there doesn't seem to be a way to identify
> the one handler I want to delete (if I want to remove the handler)
> - If I create only one gen_event for each event type and make the
> event_handlers be gen_server, I run into a similar problem (how do I call
> all the gen_servers that I want).
> Thanks for any ideas!
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