External Solidity Contract Calling

External.sol

pragma solidity ^0.4.11;

contract TokenPrototype {
  function transfer(address to, uint256 value) public returns (bool) {}
  function name() public view returns (string) {}
}

contract Client {
  TokenPrototype  _t; // We can see the transfer function

  function Client(address serviceAddress) {
    _t = TokenPrototype(serviceAddress); // _t will be the "TokenPrototype" located at serviceAddress
  }

  function send(address to, uint256 value) public returns(bool) {
    return _t.transfer(to, value); // message/response to Service is intuitive
  }
  
  function getname() public view returns (string) {
      return _t.name();
  }
}