Android : Socket in Service + Notification

I was wondering the other day if it was possible to use the service to keep active sockets, until the destruction of the service? It 'a very interesting thing that I have not learned well, plus you could add a notification that indicates the status of connection to the socket. Does anyone have examples to show you if only to understand how a service should be built with the socket? I thank you in advance

ps: I looked on StackOverflow but I have not found much explanatory examples