Developing a Plugin – sending data to WordPress webrequest

Hi all,

Hopefully I have the right forum, if not I apologise.

I am writing a plugin that needs to receive some data from an external location – an application on a server that will send bits of info across to a wordpress site. How would I go about creating a webrequest (POST I guess) to send data to wordpress? In the plugin I am going to create a function that initialises when a certain query/flag is sent to the site, and verifying it against a key that must be the same on both sides.

Can anyone point me to any tutorials or good resources to help me out?

Cheers