Solidity contract for members in an escrow payment

Purchase.sol

pragma solidity ^0.4.4;

contract Purchase {

  	address public buyer;
  	address public seller;
  	address public arbiter;
  	// uint public balance;


  // constructor
  function Purchase(address _seller, address _arbiter){
  	buyer = msg.sender;
  	// balance = msg.value;
  	seller = _seller;
  	arbiter = _arbiter;
  }

  function getArbiter() constant returns (address) {
  	return arbiter;
  }

  function getSeller() constant returns(address) {
  	return seller;
  }

}