RE: [SWMP] introducing RPC to an asynchronous protocol

"Tony Parisi" <> Fri, 24 August 2007 17:58 UTC

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From: "Tony Parisi" <>
To: "'Jay C. Weber'" <>, <>
Subject: RE: [SWMP] introducing RPC to an asynchronous protocol
Date: Fri, 24 Aug 2007 10:58:24 -0700
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If we're talking about an either/or I prefer pub-sub to readback.





From: Jay C. Weber [] 
Sent: Friday, August 24, 2007 9:04 AM
Subject: [SWMP] introducing RPC to an asynchronous protocol wrote:

D)  I believe that swmp will need the full complement of CRUD (create, read,
update, delete) operations.  I think the absence of read methods derived
from the implicit subscription to all state.  Now, that one can subscribe to
some, but not all of the state, I believe it will become desirable to
request the values of unsubscribed state.  This prompted me to add a GETNODE
and a GETFIELD request, which required GETNODEREPLY and GETFIELDREPLY
messages to return the response. 

Interesting, but the danger here is "return the response".  There's a big
advantage to resisting the introduction of RPC-style elements in a context
of minimizing latency -- obviously RPC involves a round-trip of messaging.
Keeping SWMP asynchronous will keep it mapping simply and efficiently onto
datagram transports.

I like the PUB-SUB suggestions you've made, especially because PUB-SUB can
be designed to work well in an asynchronous protocol.


Jay C. Weber, Ph.D. 
CTO, Media Machines Inc. 

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