Readivan is a booking system for van services. My role in the website was to
integrate their existing 3rd party system with the website. So for every
availability check I send binary packed to a php socket connection to their
server. Each byte is encoded as an int, char, long, etc to send specific
requests. This was a dunating task in the sense of if a packet has false length,
order something else is wrong, it will lock up their entire server. So a great
deal of integraty testing was done before hand.
See more at Readivan