Re: Intermediary Discussion

A topic of great interest:

Martin G. asked and James S. responded:

<snip>

> If a given intermediary is the 'target' for more than one 
> extension block in
> an XP message does a processing order need to be defined and 
> is so how do we
> define it?
> 

Yes, a processing order needs to be defined. As to how to go about doing
that, right now I have no suggestions.

</snip>

Just curious... what is the reasoning behind this assertion? I only ask because 
the (currently undefined) interface between XP processors and XP Module
processors will be profoundly influenced (I think) by this requirement. 
I suppose that in the simplest case, the extension blocks would be considered to 
be orthogonal to each other and the module processor(s) involved wouldn't care 
about ordering. On the other hand, of course it may be true that dependencies 
exist between the extension blocks. But why not let the XP processor sort all 
that out, since it has the required app-specific knowledge, and dispatch to the 
module processors as it sees fit? My worry is that such a rule might lead to 
fragility in the presence of intermediaries who manipulate the header contents.
They might then inadvertently break the ordering intended for "other" actors 
downstream. A sufficiently robust system might be quite complicated.

I am assuming that you are talking about application level extension block 
processing, not XP level. Please let me know if I am misunderstanding the scope 
of the question above.

RC

Received on Wednesday, 7 February 2001 15:38:27 UTC