final Unmarshaller unmarshaller = getUnmarshaller();
unmarshaller.start(createByteInput(input));
expectHeader(unmarshaller, DomainClientProtocol.PARAM_HOST_NAME);
String hostName = unmarshaller.readUTF();
expectHeader(unmarshaller, DomainClientProtocol.PARAM_SERVER_GROUP_NAME);
String serverGroupName = unmarshaller.readUTF();
expectHeader(unmarshaller, DomainClientProtocol.PARAM_SERVER_NAME);
String serverName = unmarshaller.readUTF();
server = new ServerIdentity(hostName, serverGroupName, serverName);
expectHeader(unmarshaller, DomainClientProtocol.PARAM_SERVER_MODEL_UPDATE);
update = unmarshal(unmarshaller, AbstractServerModelUpdate.class);