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At 03:34 PM 2/28/2003, Tim Bray wrote:
>>In a messaging model, the creator and receiver of a
>>document have the opportunity to negotiate prior
>>agreements such as schemata, use of binary serializations,
>>particular APIs, etc. in order to produce more efficient
>>communication.
>
>To the extent that you minimize the negotiation, you win. This is true on
>several levels. First, to the extent that the data is self-documenting
>and doesn't require callouts to schemas, format converters and so on, you
>remove failure points. Second, to the extent that you have to agree on
>these things, it slows you down. Very significant systems (for example,
>more than one of the big general-purpose portals) have XML-mediated
>systems where they sorted things out by emailing examples back and forth.
Yet there are other reasons one might like the messaging model (or the
"contract" model as another way of looking at it). Walter has used the word
"cartel", which however strong, bears thinking about (not just reacting
to). The relative expense and lack of efficiency of systems relying on such
an infrastructure (thus gaining efficiency at one level by sacrificing it
at another) is okay, since it helps limit who can afford to play (and makes
those who can more dependent on the infrastructure's maintainers).
Sometimes it seems that each side feels that they are saying we can all
have our cake and eat it too, while the other is trying to take the cake
away. What is elusive is the larger picture, the ongoing effects of
introducing external dependencies however subtle, even while we are trying
to extend the power and reliability of the tools and applications.
Regards,
Wendell
___&&__&_&___&_&__&&&__&_&__&__&&____&&_&___&__&_&&_____&__&__&&_____&_&&_
"Thus I make my own use of the telegraph, without consulting
the directors, like the sparrows, which I perceive use it
extensively for a perch." -- Thoreau
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