You need to define this function in printer.api as when client program is compiled, according to the .adef file, it will know it is a IPC function to call the printer_Print() in server.c.
Also in this definition in printer.api, it will declare the message format to pass from client program to server program.
In the server program’s .cdef file, it declares “printer = printer.api” and in the printer.api, it defines the function Print().
So that is why we need to have a function called printer_Print() in server.c.
Thank you for your replay
now I get it, I don’t know why I thought that printer_Print() is like printerPrint() but it is like prefix that refers the variable printer in cdef and after _ comes the function name defined in api file. All clear now