[Hawkular-dev] [metrics] Looking for advice on ListenableFuture usage

[John Mazzitelli]

I find trying to write the same functionality in straight JMS will show the usefulness of MessageProcessor.sendRPC.

Again, this is to support RPC-like functionality - which isn't trival in JMS (as opposed to fire-and-forget, 1-way messaging). You wouldn't use this sendRPC if you are just shooting a message on the bus and not expecting a direct response to that message.

----- Original Message -----
> 
> > On Jan 16, 2015, at 12:20 PM, John Mazzitelli <mazz at redhat.com> wrote:
> > 
> >> I haven’t looked at the code too closely yet, but why the need for
> >> ListenableFuture to get the response from the bus? JMS/messaging is
> >> already
> >> asynchronous.
> > 
> > In the RPC-like use-case, I send a message on the bus, and I expect to get
> > a response back from that message. This API helps hide the annoying JMS
> > boiler-plate code you'd have to write to do that RPC-like functionality.
> 
> But aren’t you just putting in place more boiler plate with ListenableFuture?
> The problem with Java futures is that obtaining the result is blocking.
> ListenableFuture allows you to get the results asynchronously. We already
> get the results asynchronously with JMS right? I understand the desire for
> abstracting the JMS code, but I don’t what ListenableFuture buys you.