How to connect Sap portal with non SAP Systems?

H Experts,

How to connect sap system to non sap system(in portal side) as well as basis side?

for example

1. i hvave a PHP application this app available in diff system that PHP app wanted to interated into portal How? in portal side what we have to do?

2 Connect to different non SAP Systems how?

Regards,

VReddy