Run php script from other server hidden

[StoutFiles]

I have two servers, A and B. Only server B has the php libraries to run a php script that generates an image. Server A embeds this image from server B.

When a user clicks a button on server A, how can I run the php script hidden on server B to generate a new image for A to show?

[brotherhood of LAN]

Use curl or similar to call a URL on server B. Make it so that a secret password/cookie string is needed in order to fulfil the request.

[penders]

If your script is returning an image that you want to show, then can you not do something like...

<img src="http://www.serverB.com/my-script.php" alt="">

?

[brotherhood of LAN]

That'd be an easier way penders but it'd make server B's URL public.