How to implement a communication channel between two android devices over the internet

Does anyone know how to implement communication between 2 android devices over the internet without using App Engine? For example, I have 2 Android devices, and I want to send a stream of data from one to the second one over the internet. I would like to know, if someone could give me an idea, how could I identify the second device (or how to create a communication channel between two devices ), so I could initiate the transfer (this is not possible using IP addresses ?).If i were to have my own server, which is the best way to go to accomplish this? If someone could point 开发者_JAVA百科me to some useful resources I would be grateful.I have some background on android programming. One way I was thinking to accomplish this was to write an android application, and when the user enters it, it will start a service. This service will then listen for network events and registers on my own server with the username and the IP address of the device as available.When another device wants to send data, it will connect to the server, search for the target device (by username key), gets the IP address and sends the data. Could this work, or does anybody have other suggestions?

One way I thought about doing this is making

(excuse the spelling mistakes if any)

It would help if we knew what kind of data you were trying to transfer.

For small bits of information, like notifications, events, and the like, I would suggest doing an HTTP POST to a server that has C2DM capabilities, and using the server as an intermediary.

For larger data, the only way I can think of to do it is to set up a SyncAdapter, then upload the information to the server. The delay will be a bit longer, but you'll reliably get the information downloaded from the server to the phone. So less of a communication API and more of a dropbox for phones.

I haven't done much with NFC, but that may be something you want to look into.