case RELEASE:
replicator.release(extractRequestParam(req, REPLICATE_SESSION_ID_PARAM));
break;
case UPDATE:
String currVersion = req.getParameter(REPLICATE_VERSION_PARAM);
SessionToken token = replicator.checkForUpdate(currVersion);
if (token == null) {
resOut.write(0); // marker for null token
} else {
resOut.write(1); // marker for null token
token.serialize(new DataOutputStream(resOut));