Heya!
I just realized something - the way that workflows currently work does
not scale. The problem is that preSaveTask stashes all of the
attributes of the page into memory (and assumes it can serialize it).
Now, in 3.0 the attribute map cannot exist, since e.g. page content
will be an attribute. This means that attributes can span gigabytes
(like with attachments), and you probably don't want those in memory.
Another problem is that copying all of the attributes and restoring
them will probably cause all the attributes to be versioned again
since we overwrite all attributes with the ones from memory. That is,
every single versioning will create complete copies of all attributes
since we rewrite all of them each time... Though this could very well
be something that the repository does anyway, but at least we're not
helping it.
This means that the whole workflow storage will need to be rethought a
bit. My current idea is that we just simply add a new Node in the
repository:
/wiki:workflows/
and we add the workflow information into that repo as a series of
Nodes. For example:
/wiki:workflows/<workflow-id>/<node-uuid>/<modified attributes>
This allows a couple of things to happen:
1) workflows are clustered automatically
2) we don't need serialization anymore, since we just copy JCR
Properties back-n-forth
3) workflows are persisted automatically
4) workflows could in the future contain multiple objects
5) workflows can be exported and backed up together with the repo
contents
How does this sound? We do also want to create a canonical
representation of a workflow object, and this might need a bit of
design. I'm not *that* familiar with the way it works, so some help
might be needed here.
/Janne
