In a micro map battle we all know the computer likes to rush. Here is a strategy that i came up with to prevent from getting rushed.

First off, Build a pylon within the radius of your Micro Map Entrence. Collect enough minerals to build a forge quikly. (it is also smart to build around three more probes for faster money).
when the forge is complete, Build one cannon on the inside of your entrence on bothe sides (not blocking the entrence, Nor in the entrence) and then build a Gateway in between the walls of your entrence.

Now you cannot be rushed, even if all the computers decided to rush you at once. Because of the Gateway and the cannons shooting at them they will try to get to the cannons first. but since the gate way is in the way, they just run around like chickens with there heads cut off while getting shot at.

CreepColony's Opinion: This is similar to the supply depot thing with Terran, but not as easy. I find that just cannons can easily hold off a comp rush.