ProxyMachine is a simple content aware (layer 7) TCP routing proxy built on EventMachine that lets you configure the routing logic in Ruby. The idea here is simple. For each client connection, start receiving data chunks and placing them into a buffer. Each time a new chunk arrives, send the buffer to a user specified block. The block's job is to parse the buffer to determine where the connection should be proxied. If the buffer contains enough data to make a determination, the block returns the address and port of the correct backend server. If not, it can choose to do nothing and wait for more data to arrive, close the connection, or close the connection after sending custom data. Once the block returns an address, a connection to the backend is made, the buffer is replayed to the backend, and the client and backend connections are hooked up to form a transparent proxy. This bidirectional proxy continues to exist until either the client or backend close the connection.