How can I return the infomation of components connection in schematic file?

Hi,

Now I want to build a c code description of schematic files. I open one top level schematic file, and get its cellview ID. And I can also return the components within this schematic. Now I want to know the connections of these components so that I can describe it in c code file. So I need the infomation about the output pins and input pins of these components and the wire connections. How can I return the infomation? For example, I open a schematic file describing a PLL, and I get some components like VCO, Lowpass Filter, divider, etc. If LPF's output pins are connected with the input pins of VCO, so how can I get this infomation using some functions?

 Thanks very much for your help!