[ZPatterns] Revisiting an old question: Reusable ZPatterns applications

[Itai Tavor]

Steve Alexander wrote:

>I'd just composed a reply to this, when we had a 2 hour power-cut :-/
>
>Here goes my second try.

I'm impressed :-) If this had happened to me, all you'd get would be 
"I replied to your question, but the reply was lost. Sorry."


>Itai Tavor wrote:
>>
>
>Second, and this is where the whole thing becomes quite impossible, 
>there's the problem of upgrading the application, for bug fixes or 
>feature changes. With a normal app, you install a new copy, refresh 
>the product, and you got the new application working with all your 
>existing data.
>
>
>My procedure for this goes like this:
>
>1: Export data from Racks to an xml file on the filesystem
>2: Install new Data.fs / Zope+Python+Data.fs+External Methods etc.
>3: Reimport data from Racks
>4: Update Catalogs (in dependency order) from the ids in the imported data
>
>Note that when I say "export as xml", I mean to a domain-specific 
>xml DTD using an external method.
>
>The advantage of this is that it is easy to migrate the application 
>between very different schemas. I needed to do this when I converted 
>an application from Specialists+Racks and Customizers to just 
>Specialists+Racks.

This is a good procedure for some cases... like, when you've made 
major changes to a one-of app code, or, as you say, when you're 
migrating to a new schema. But I don't think it's really feasible for 
the case I'm talking about. Doing this procedure across 20 app 
instances is IMO just too much work, as well as too risky.

BTW, you mentioned your xml export/import methods before... even 
though they're domain specific, could I see a copy to get me started 
on cooking my own? Unless, of course, the domain-specific parts 
contain confidential information...
-- 
--
Itai Tavor                      -- "Je sautille, donc je suis."    --
itai@optusnet.com.au            --               - Kermit the Frog --
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-- "If you haven't got your health, you haven't got anything"      --