Namenode and jobtracker also startup an http server which is jetty. The http interface is used to look at namenode health, status of datanodes, to browse the file system, or in case of job tracker to view job status, task tracker status etc.
JT and TT also use the same RPC mechanism to talk to namenode using the file system interface. On 8/12/10 6:59 PM, "Ahmad Shahzad" <ashahz...@gmail.com> wrote: Hi Momina, Thanks for replying. I wanted to know that JT and TT interact with each other through this RPC Server and Client model, What about the http Server Jetty.... what is it used for ?? Secondly, i would like to ask a related question, how does JT and TT communicates with namenode and datanode?? Do they use the same RPC server client mechanism or is there something else used for communication between them. Ahmad