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From Christian Haul <>
Subject Re: Flowmaps: the wrong approach (was Re: [RT] (long) Rethinking Finite State Machine Approach to Flow Management)
Date Mon, 03 Dec 2001 09:50:21 GMT
On 01.Dec.2001 -- 02:54 PM, Stefano Mazzocchi wrote:
> Ovidiu Predescu wrote:
> I like the concept of "continuations". Sitemaps are completely
> declarative and for this reason they don't provide a simple way to
> perceive the "flow" between stages.

I'd like to second this oppinion, continuations look cool. OTOH will
that scale? There are many around that don't like sessions because
they require the server to devote memory for every session. OK, only
*applications* would use them, so that's propably all right.

> Yes, the flowmap alone would be kind of useless since it would be biased
> toward flow and fail to describe states. Just like the sitemap describes
> states but fails to describe transitions.
> The statemap should bring the two world together. What syntax we use to
> express it, is not something I'm really concerned at this point.

I think the sitemap as a representation of a FSM is quite OK. Once you
start matching on other things than URIs (e.g. session attributes or
referer header i.e. your *current* state in addition to the requested
transition), all aspects of an FSM can be modelled. 

I think a Flowmap will not ease the maintenance a lot because a FSM is
a highly complex graph and whatever you do, an XML file can only
describe tree structures well. Hence, again, things start spreading
around. The only solution I see, is to describe single states and all
transitions available from that point on, depth 1. And that is exactly
what the sitemap is today.

In my opinion two things would be very cool: 1) the ability to use
macros in sitemap i.e. abilitiy to use XSLT prior to sitemap parsing
or (XSP would have some benifits, too, but I don't think it's worth
the effort) 2) integrate some tool for FSM modelling. Most likely, (2)
is for free if (1) is in place and we find some tool that writes XML


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