Realtime (almost) bidrectional communication in Java

I will explain the context of the problem first. For a University project I’m going to implement an Android application. The Android application (and others) will be able to send data to a remote source, that remote source will also be able to send messages to the Android applications. For example the messages may be “apply configuration x”, “what is your status”. I want the remote source to be able to send these messages to:

Application protocols and state machines: designing a complicated server

I’m designing and prototyping a server that has the following characteristics:

Sockets intricacies in TCP and UDP

I am quite familiar with TCP and UDP. I understand the process by which TCP establishes connections and other theoretical facts about TCP but when reading up about TCP hole punching for NAT Transversal, I have become stumped by how connect(), accept() and listen() is done in TCP. Is it a single or multiple sockets that are used for all this in TCP and is is this done the same way in UDP

Writing a TCP protocol or use HTTP for file transfer?

I want to write a server side application which allows several users to exchange files (not above 3MB) in the following way: user A connects to (server) S. User B connects to S. User C connects S. User A sends a file. Users B and C “see” that a file was/is being uploaded and start downloading it.

How do I perform some actions in my Java program whenever a particular network interface comes up?

I wanted to perform some actions in my Java program whenever a particular interface comes up (network interface ppp0 e.g.). However I figured out it was way too clumsy to keep polling the interface to verify its status.

Server distribution for high performance

I’ve developed a Socket Application on top of TCP in .NET C#, which allows many clients to send files from one another via a VPS I’m using. Most file transfers will occur between people in the same region, say, even in the same neighborhood.

UDP order of packets with direct connection

If i have two systems (A and B) running on LAN(INTRANET) which are directly connected. There are no routers in the middle. In this case, if system A sends a few UDP packets every few milliseconds to system B:

Non Blocking Sockets vs Blocking sockets – UDP – C&linux

When to use blocking sockets over non blocking sockets on UDP?

Are Python sockets suitable for file synchronization?

I’m working in an organisation with limited funds. They can’t afford a business account on Dropbox. However, they would find it useful to have all their files synchronized on local machines.

Protocol for closing a socket connection

I’m rolling my own application protocol on top of TCP. I’m using Linux and C. I’m wondering whether there is an advisable sequence to closing a socket connection.