title: Which network protocol to use to sync resources between a server a several clients
body: <p>I am building a professional iOS application where an iPad is a server and several iPhones are clients.</p>
  
  <p>Considering the fact that :
  - communications operate only on a local network via sockets using TCP.
  - I want to keep all of them in sync (all devices have a local database)
  - I want to be able to send commands like NEW, UPDATE, DELETE, etc to keep them in sync
  - I want be able to send notifications with some data attached (audio file),
  - I want to define priorities for all of theses commands.</p>
  
  <p>It makes me think that a need to define a protocol, so my question is : Does one already exist ?</p>
  
  <p>Thanks a lot !</p>