HTTPS transactions with PHP

With more and more e-commerce sites popping up around the world, the amount
of transaction servers will need to grow to support them all. Many of the
newer e-comms providers have made life easier for us developers by developing
a web based environment to execute their transactions. Let me explain.

What do they do ?

While some providers make you install application on your servers to talk
to their servers a lot now avoid that situation by doing the following.

1. Setup an HTTPS server that is locked down to only your IP
2. Setup a page on that server that listens for a specific set of values
3. When you post to that server, it takes those values and does whatever it

has to do (talk to the bank, setup an account etc..)

4. Returns a page with the results in it.