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Re: Dependency management (again)

From: Innovimax SARL <innovimax@gmail.com>
Date: Wed, 4 Apr 2007 17:49:39 +0200
Message-ID: <546c6c1c0704040849o60824519x263721c5e00e57c8@mail.gmail.com>
To: "Henry S. Thompson" <ht@inf.ed.ac.uk>
Cc: "Norman Walsh" <Norman.Walsh@sun.com>, public-xml-processing-model-wg@w3.org

I share Henry's concern that depending on a step is too fuzzy

But, depending on an input is something i feel necessary even for V1

In that case, you have to create accessory output (which will contain
dummy (or not) things), and say in the *following* component that it
depends on this output

I know that some of the question raised by Henry remains unsolved, but
we can pick one (say output has started to be produced) and stick to

The more, I think, the more I agree with Henry saying that Errors
discussions should start first

My two cents


On 4/4/07, Henry S. Thompson <ht@inf.ed.ac.uk> wrote:
> Hash: SHA1
> Nightmare!
> If I depend on a step, what does that mean?  That I don't start until
> it has started?  Until it has finished?  Until its output has
> finished?  What if it produces error output?  What if it has multiple
> outputs -- can I start once its primary output has finished?  Will we
> rule out explicit deadlock?  Implicit deadlock (I use your input, you
> depend on me)?
> What will you want next -- a guarantee that the db-query step will
> read what the db-update step wrote, even in the presence of multiple
> pipeline activations (i.e. atomicity)?
> Maybe we should delay discussing this until we've discussed errors,
> because if we end up providing some kind of transaction support, some
> of these problems will go away and/or be given useful background.
> My inclination for v1 is to just say "no dependency mechanism", and
> for now that you should build your db-update step to provide some form
> of trivial output, e.g.
>  <my:wroteRecords n="3"/>
> , and ignore it if you don't need it, but use it to sequence
> subsequent steps if need be (e.g. in this case by wrapping the 'query'
> step in a p:for-each select='my:wroteRecords'. . .)
> ht
> - --
>  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
>                      Half-time member of W3C Team
>     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
>             Fax: (44) 131 650-4587, e-mail: ht@inf.ed.ac.uk
>                    URL: http://www.ltg.ed.ac.uk/~ht/
> [mail really from me _always_ has this .sig -- mail without it is forged spam]
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> =hUjk

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Received on Wednesday, 4 April 2007 15:50:01 UTC

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