Interface with DatagramSocket
http://msdn.microsoft.com/en-us/library/windows/apps/windows.networking.sockets.datagramsocket

Set the event handler
http://msdn.microsoft.com/en-us/library/windows/apps/windows.networking.sockets.datagramsocket.messagereceived

Then bind (asynch):
http://msdn.microsoft.com/en-us/library/windows/apps/windows.networking.sockets.datagramsocket.bindendpointasync

Close socket:
http://msdn.microsoft.com/en-us/library/windows/apps/windows.networking.sockets.datagramsocket.close

SystemAddress to / from IPV4, IPV6

Domain name to IP lookup

Lots of info here:
Do not use ConnectAsynch, because you cannot get datagrams from any remote address, only those you have connected to.
http://msdn.microsoft.com/en-us/library/windows/apps/windows.networking.sockets.datagramsocket

Send:
When sending to a new system, use GetOuputStreamAsynch http://msdn.microsoft.com/en-us/library/windows/apps/hh701265. When it completes, send the data using 
DataWriter http://msdn.microsoft.com/en-us/library/windows/apps/windows.storage.streams.datawriter.aspx
Use WriteBuffer, then StoreAsynch.

http://msdn.microsoft.com/en-us/library/windows/apps/hh701265
For each connection, need GetOutputStreamAsync, which specifies a hostname (IP address) and port.

Set TTL:
Use control:
http://msdn.microsoft.com/en-us/library/windows/apps/windows.networking.sockets.datagramsocketcontrol#properties

Receive:
http://msdn.microsoft.com/en-us/library/windows/apps/BR241344
DatagramSocket^ listener = ref new DatagramSocket();
ListenerContext^ listenerContext = ref new ListenerContext(rootPage, listener);
listener->MessageReceived += ref new TypedEventHandler<DatagramSocket^, DatagramSocketMessageReceivedEventArgs^>(listenerContext, &ListenerContext::OnMessage);

Sample:
http://code.msdn.microsoft.com/windowsapps/DatagramSocket-sample-76a7d82b
http://blogs.msdn.com/b/trycatchfinally/archive/2012/09/06/welcome.aspx

Closed forum questions:
Datagram Socket receive from any sender
http://social.msdn.microsoft.com/Forums/en-US/winappswithnativecode/thread/2d732e1b-a9a1-4195-bfe5-216a75fb4319/
DatagramSocket: When I get MessageReceived, how do I actually read the data and who it was from?
http://social.msdn.microsoft.com/Forums/en-US/winappswithnativecode/thread/ae568041-a080-4194-a783-94b6bc48852d/
DatagramSocket; GetOutputStreamAsync asynch?
http://social.msdn.microsoft.com/Forums/en-US/winappswithnativecode/thread/cbbf610a-bcff-47f1-b930-e79c36a5f53e/

Open forum question:
http://social.msdn.microsoft.com/Forums/en-US/winappswithnativecode/thread/ce47bbae-80a0-460c-b738-3a752b0d4d3a

Programming language is C++/CX
http://msdn.microsoft.com/en-us/library/windows/apps/hh699871.aspx

Concurrency task
http://msdn.microsoft.com/EN-US/library/hh750113(VS.110).aspx
http://blogs.microsoft.co.il/blogs/pavely/archive/2012/06/25/windows-8-metro-c-cx-vs-c.aspx

http://social.msdn.microsoft.com/Forums/en-US/winappswithnativecode/thread/8a72dda7-dd25-4356-b830-f33b35784af0
How to callback to existing C++ from C++/CX?

I have a large body of C++ code that I am trying to integrate with Windows 8 Store. In the existing code, I use a pure virtual interface for when a network message arrives
class RNS2EventHandler {
	virtual void OnRNS2Recv(RNS2RecvStruct *recvStruct)=0;
};
class RakPeer : public RakPeerInterface, public RNS2EventHandler {
	virtual void OnRNS2Recv(RNS2RecvStruct *recvStruct) {DoStuff();}
};

In Windows Store 8, I get this callback when a network message arrives
public ref class ListenerContext sealed
{
public:
void OnMessage(Windows::Networking::Sockets::DatagramSocket^ socket, Windows::Networking::Sockets::DatagramSocketMessageReceivedEventArgs^ eventArguments) {
// Need to call the C++ callback
}
}

If I try putting a RNS2EventHandler* inside ListenerContext the compiler complains that I can't put C++ types inside a C++/CX class.

So how do I implement a callback to notify C++ when ListenerContext::OnMessage occurs? As a last resort I can poll ListenerContext in a thread from the C++ code, but that ruins performance and the whole point of a callback. But I'll do it if there is no straightforward alternative.

Thanks in advance.