code: function readMessage(socketData, signer) {
    var identities = socketData[0];
    var signature = socketData[2].toString();
    var header = socketData[3];
    var parentHeader = socketData[4];
    var metadata = socketData[5];
    var content = socketData[6];
  
    if (!signer.validate(signature, [ header, parentHeader, metadata, content ])) {
      return null;
    }
  
    return createMessage(identities,
                         JSON.parse(header),
                         JSON.parse(parentHeader),
                         JSON.parse(metadata),
                         JSON.parse(content));
  }
docs: Helper to read in a message from incoming message data.