I'd like to be able to use service discovery APIs (e.g. jmdns) on the client to find services running on the client's local network (in a desktop app).
Not knowing a huge amount about RAP architecture, with the code actually running on the server does this mean it's not possible to do this? Would the API calls only discover services running server-side?!
Thats right. Using service discovery APIs (e.g. jmdns) would only discover services running on the server side. The Tabris client for iOS is written in pure Objective-C and only renders the UI of the Java Application that runs on the server and provides access to native functionality on the iOS device.