To know about RPC Vs document

Hi,
we are creating a eclipse plugin for converting C++/C files to wsdl files.
In this i'm facing a problem which is don't know difference between
RPCTypes and Document Types.what are difference, which want to put, when I
write wsdl file's complexType. At what instant which i want to put
sequence || all , elements || attributes || any , complexContent.
                           waiting for your kind reply.
                                         Thanks.