22. The system of claim 21 , wherein the master search node registers with the message provider to listen to the index update event produced by a slave search node.
22. The system of claim 21 , wherein the master search node registers with the message provider to listen to the index update event produced by a slave search node. 23. The system of claim 22 , wherein each of the slave search nodes periodically polls the master search node to copy the index directory information in order to update the local copy of the slave search node.