title: java serialization across networks data integrity
body: <p>How to ensure data integrity when sending serialized objects across networks.
  Implemented example would be helpful.
  One way could be to use java.io.Externalizable with java.security.MessageDigest
  But this is requires a manual serialization.
  I think that is bit risky, so i would not want to use it.
  Is there any other way?</p>