Designing socket messaging format

Manoj Plakal terabaap at yumpee.org
Tue Nov 13 07:31:50 CET 2001


Steve Holden wrote:

> "Manoj Plakal" <terabaap at yumpee.org> wrote in ...
>>          This might cover a lot of cases where you don't
>>          need RPC semantics (no return value expected)
>>
> 
> But some sort of response will usually be required, even if it's a simple
> ACK.


	    Sure, there will be situations where you
             want an ACK, in which case you want
             to do RPC. Or maybe you'd want an asynchronous
             response instead of waiting for it. But
             I believe there will be some cases where
             you just want to send a notification and
             not wait for anything.


>>          and you're sending simple data values (so no
>>          need of full-blown XML or other elaborate encoding).
>>
> 
> How simple is simple? ASCII strings of less than 256 characters you might
> get away with...\


	    I was thinking about fixing a grammar and
             then having a parser for this grammar rather
             than having a general XML parser and giving
             it the DTD for the protocol.


>>          And you may not even need a reliable transport
>>          protocol (so no need of HTTP or even TCP).
>>          XML-RPC is cool but it seems like a really
>>          big and overweight hammer.
>>
> Oh, so you don't mind if Word prints file "xyy.doc" when you ask it to print
> "xyz.doc"?


	    By reliable, I meant stuff like acknowledgments
             and sequencing and all that. I assume that
             the data payload itself is protected from
             corruption. Doesn't UDP have checksums?


> Can we say "UDP?


             Sure you can use UDP, but I don't want
             to use a separate application-level protocol
             on top of UDP for each app I write or talk to.

             I'm not trying to reinvent a new network
             protocol here. All I'm asking is if there's
             some kind of cross-platform ultra-lightweight
             COM/CORBA-kind of messaging system, built on top
             of some IPC mechanism (UDP or domain sockets or named
             pipes or something not too heavy).

             I did find a link to XPLC: xplc.sourceforge.net

             Manoj




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