Android Question Mqtt chat autodiscovery multiple App

[postasat]

Hi,
is it possible to use two app in the same device to chat with the same server app ?
if I use the same port for two app, I have an error (EADDRINUSE).

If I set two different port in every "client" app (for example 51042 and 51043) what I must change in the server app ?

Thank you.

 

[Erel]

Which server are you communicating with?

Why are you using UDP discovery?

 

[postasat]

Hi Erel,
i use a tablet as server (on the same wifi net with my phone) and I need to have two different app on my phone (with the same mqtt autodiscovery function), I will start one app or the other when needed.
When I exit from one app and I start the other app, the app doesn't start and crash with error (EADDRINUSE - same address).
I had an error too, launching one app as first after phone restarted (maybe android launch "starter" on startup ?)

Is it possible to use two different port for every app with only one "server" ?

Thank you.

 

[Erel]

The problem here is with the UDP socket that is opened exclusively. You can catch this exception and ignore it if your app can work without auto discovery.

Another option is to make sure that the USPSocket is closed when the app goes to the background.

 

[postasat]

Hi Erel,

I could move all the instruction from Starter Service_start to a new Starter subroutine and call it only when I need to start the chat with autodiscovery function.
when I exit the "connection" function/activity in my app, I could call another Sub in Starter to close the Udp with

autodiscover.Close

.

If I stop with

autodiscover.Close

it's enough to launch the same chat with autodiscovery function in another app or I must close the broker too ?

Thank you.

 

[Erel]

The "address in use" problem is related to the UDP socket. Assuming that the apps do not open any other port for incoming connections then it should be fine.