Issuing RPCs

Table of contents

1. Example
2. Calling ECHO

You have now fully implemented the ECHO RPC. You will now call it from a client.

Example

An example of issuing an RPC is shown in the example function in kv_store_client.c:

int example(int input) {
  CLIENT *clnt = clnt_connect(HOST);

  int *result;

  result = example_1(&input, clnt);
  if (result == (int *)NULL) {
    clnt_perror(clnt, "call failed");
    exit(1);
  }
  int ret = *result;
  xdr_free((xdrproc_t)xdr_int, (char *)result);

  clnt_destroy(clnt);
  
  return ret;
}

The function first connects to the RPC server, then issues the RPC by calling the example_1 client stub. It then recovers the result by dereferencing the returned pointer, frees the memory allocated by the RPC, closes the client, and returns the result.

Calling ECHO

Now implement the echo function in kv_store_client.c so that it calls the RPC you just implemented. You should ensure that you are making the call to the server rather than just returning the input locally (you will not pass the autograder tests otherwise).

We recommend copying the implementation of example and changing the necessary types to make sure you are following all of the necessary steps. Keep in mind that you will need to duplicate the returned string using strdup before freeing the XDR structure with xdr_free((xdrproc_t)xdr_string, (char*)result).

Compile your code with make. You should now be able to test your ECHO RPC by starting the server with ./server and calling the function you just implemented with ./client echo test. You should see the output test.