How to Write a TCP Echo Server in Ruby
How to Write a TCP Echo Server in C
In c you are as close to the metal - or at least as close to the os - as possible in a high-level language. This shows in the verbose code you need to make a simple tcp server which echos messages back to the client. Furthermore this implementation of the server will only ever accept one client - and when that client disconnects, the program exits.
How to Write Xml in Ruby
In Ruby there is no built-in support for parsing and writing xml. There are however a couple of gems (packages) that allow you to do exactly this. If you are working in Rails - you have this for “free” with ActiveSupport (which you could also just require as a standalone package). This gives you a to_xml on a hash which is dead easy to use. There is also the xmlsimple gem which is a port of the same library from perl.