Re: [xml-dev] Using XML (or JSON) for inter-thread communication

["Pete Cordell" <petexmldev@codalogic.com>]

Thanks to everyone for comments on this thread today.  Most useful food for 
thought.

Pete Cordell
Codalogic Ltd
Interface XML to C++ the easy way using C++ XML
data binding to convert XSD schemas to C++ classes.
Visit http://codalogic.com/lmx/ or http://www.xml2cpp.com
for more info
----- Original Message ----- 
From: "David Lee" <dlee@calldei.com>
To: "Pete Cordell" <petexmldev@codalogic.com>; <xml-dev@lists.xml.org>
Sent: Monday, March 19, 2012 1:45 PM
Subject: RE: [xml-dev] Using XML (or JSON) for inter-thread communication


Nothing multithreaded is ever simplified :)
However point taken.  This is a common use case for example BPEL defines 
endpoints in such a way that can be multithreaded or multi system (but it 
uses that legacy protocol some may have heard of "SOAP").

xmlsh does this in the language itself ... for threads within an xmlsh 
runtime.
Pipelines (a | b ) are run as seperate threads.   Variables can be shared 
across threads.  Starting a new thread ( with "cmd &" ) can share 
(copy-on-write)  all exported variables from the parent environment and can 
return values but outputting to a named port.
Out of process or server communications  can be shared by starting a mini 
HTTP server (httpserver) and then data (xml or otherwise) can be pushed 
through it.

Similarly XProc is designed so it could be multithreaded or multi-server. I 
dont know of any implementations that currently do, but the design was 
intended to allow such a  thing.

And one step up.   the entire internet is designed this way.
Although protocols and implementations vary.


----------------------------------------
David A. Lee
dlee@calldei.com
http://www.xmlsh.org

> -----Original Message-----
> From: Pete Cordell [mailto:petexmldev@codalogic.com]
> Sent: Monday, March 19, 2012 9:34 AM
> To: xml-dev@lists.xml.org
> Subject: [xml-dev] Using XML (or JSON) for inter-thread communication
>
> We all know that increasing processor speed has pretty much run its course
> (for now) and that the way to increased system performance is via using
> multiple cores and threads.  However, parallel programming is difficult.
>
> One of the problems is sharing state across threads and getting race
> conditions etc.
>
> However, systems like web services are effectively multi-process /
> multi-threaded and seem to scale well.  Quite often web services (and
> systems like them) use XML or JSON to communicate between the various
> systems.
>
> Which makes me wonder, can you compress the 'web services' model down to
> the
> level of threads and use XML or JSON for your inter-thread communication?
> Can you define your interfaces using some sort of schema and use REST or
> similar approaches?  Would this help simplify parallel programming, 
> perhaps
> as one of a basket of techniques?
>
> Does anybody have any thoughts on this?
>
> Thanks,
>
> Pete Cordell
> Codalogic Ltd
> Interface XML to C++ the easy way using C++ XML
> data binding to convert XSD schemas to C++ classes.
> Visit http://codalogic.com/lmx/ or http://www.xml2cpp.com
> for more info
>
>
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