Non blocking IO for Android

Question

I'm currently trying to assess whether a project can be realised for Android. One major problem I see it that, since it's a P2P client, we'd have to keep a considerable amount of connections open when running. Now the connections do not transfer large amounts of data, it's more of a messaging system, so having a thread for each connection creates a useless overhead if we're reading a single message of 64 bytes every now and then.

So I was wondering whether there is support for non blocking IO such as select() or poll() on Linux.

Any suggestion?

Answer 1

Check out java.nio Sockets, Selectors, and Channels. Some links:

Android: Unbuffered IO http://developer.android.com/reference/java/nio/channels/ServerSocketChannel.html http://developer.android.com/reference/java/nio/channels/SocketChannel.html http://www.developer.com/java/article.php/3837316/Non-Blocking-IO-Made-Possible-in-Java.htm

Or, maybe I didn't read your question right.

Answer 2

Of course. Once your application declares uses internet permission, you can do all normal linux networking things normally available to a non-root user in C using the NDK, and any of them from java that someone (possibly you if no one beat you too it) has bothered to write support for.

Well, one exception: your mobile provider probably won't permit incoming connections, and neither will most wifi routers unless you specially set them up to. But those are infrastructure issues rather than issues with android itself.

You will probably also need to come up with some combination of an Activity to provide the foreground UI and a Service to continue the actual transfers in the background with just a status bar icon showing.