Invoke the bonjour service in an asynchronous non-blocking fashion

[cescoffier]

This way is compliant with Vert.x.

Notice that I had to change the service interface to use an Observable as it's the only way to be async and non-blocking.

Another approach (that does not require the service change) would be to use:

vertx.<List<String>>executeBlocking(
  future -> {
     // Blocking, but running on a worker thread
     future.complete(getTheResultingList());
  },
  ar -> {
   // Back on the event loop, can write in the response
  }

Both approaches have pros and cons.

[rafabene]

Hi @cescoffier . Thanks for the PR. I'll merge it soon.

[cescoffier]

@rafabene Let me know which approach you would prefer:

• the observable (this PR)
• the executeBlocking approach

I can provide the second PR if you want.

[rafabene]

My preference would be for the one with the simplest code. I don't want the attendees to think that it's too hard or too complex when they see the code. Do you mind to send the second PR so we could compare?

Thanks so much for your support.

[cescoffier]

No problm, will open another PR today or tomorrow morning.

[rafabene]

Closing this since we decided to go with approach #2