Datagram Congestion Control Protocol (wikipedia)
The Datagram Congestion Control Protocol (DCCP) is a message-oriented Transport Layer protocol. DCCP implements reliable connection setup, teardown, Explicit Congestion Notification (ECN), congestion control, and feature negotiation.
[DCCP] allows for flow-based semantics like in Transmission Control Protocol (TCP), but does not provide reliable in-order delivery.
This seems like a great deal instead of implementing it in the application layer. A big disadvantage of TCP usage in application with real-time networking requirements is that each and every packet is always resent, and newer data might wait for stale data.
Are there any implementations of this protocol, native or otherwise, in Windows and some standard Unix systems? Any preferably cross-platform libraries that extend the standard libraries of C#, Java, C++ with this functionality?
You won't be able to implement it in pure JAVA without HUGE problems (if it's possible at all) because networking is handled by the JVM and basically support only TCP and UDP (ICMP is not implemented for example though ping is partly available in JAVA 6)
Perhaps you could try to talk with the owner of this project ? He tried to write a JNI Wrapper
C++ seems to be a better choice. Search for libraries written in this language