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Hadoop >> mail # dev >> JobTracker/TaskTraker heartbeats communication mechanism?


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Daniel Parreira 2012-06-29, 13:43
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Re: JobTracker/TaskTraker heartbeats communication mechanism?
Daniel and Joao,

The RPC classes in Hadoop handle this.  Essentially a proxy object is
create on the client side for the interface, then when a method is called
in the proxy object the parameters are serialized sent to the configured
server along with the method name, where they are deserialized and through
reflection the server method is called.  The for the return
value/exceptions it is done in reverse.

I hope this helps.

--Bobby Evans

On 6/29/12 8:43 AM, "Daniel Parreira" <[EMAIL PROTECTED]> wrote:

>*Hello,
>
>We're having some problems understanding the communication system used in
>the heartbeats between the JobTracker and the TaskTracker. They are both
>calling the same interface function, but we don¹t understand how that
>allows for communication. *
>*Is there any compiler plugin or RMI-style mechanism involved **that we
>might not be aware of?** We found the interface as the point of
>communication in VersionedProtocol but we haven't found the actual
>implementation anywhere...*
>*
>Thank you,
>Daniel Parreira & João Silva*