When to use WCF duplex vs datagram?

My app is master/slave system where slaves can send messages to the master based on a (local) event and master sends messages to the slave also based on local events.

In both cases they may send outgoing messages based on incoming messages. Sometimes these reponses may only be sent after human interaction - not immediately (and connections may be lost in the meantime).

Both master and slave will communicate over the internet using TCP.

Is this a good scenario for duplex? Or should I simply send "fire and forget" (datagram) messages and handle message progression/states/workflow within my business log开发者_JAVA技巧ic (viewmodel) layer?

Thanks!

PS. Also a discussion on when/why each is appropriate would help.

TCP duplex seems to be ideal in your case.