At 01:23 PM 9/7/2006 -0700, Brian Moseley wrote:
On 9/7/06, Phillip J. Eby <[EMAIL PROTECTED]> wrote:
To put it another way, both Cosmo and Chandler are already going to have to
have code to read, write, and understand EIM records, so why also add code
to read/write/understand an XML schema too? :) So we might as well
represent any schema information as some additional EIM records that just
have a hard-coded schema.
i hear you, but i'd like to see a concrete example to help pull it
together for me, if you have some time. thanks.
Well, let's say we have a record type defined thus in Chandler:
@sharing.recordtype("http://schemas.osafoundation.org/pim/contentitem";)
def itemrecord(itsUUID, title, body, createdOn, description, lastModifiedBy):
# details omitted
We might represent the type information as a set of EIM records like this:
("http://schemas.osafoundation.org/pim/contentitem";, "itsUUID", "UUID")
("http://schemas.osafoundation.org/pim/contentitem";, "title", "Text")
("http://schemas.osafoundation.org/pim/contentitem";, "body", "Text")
("http://schemas.osafoundation.org/pim/contentitem";, "createdOn", "Timestamp")
("http://schemas.osafoundation.org/pim/contentitem";, "description", "Text")
("http://schemas.osafoundation.org/pim/contentitem";, "lastModifiedBy", "UUID")
This provides enough data to be able to determine what record types exist,
what columns they have, and what type they are. Of course, the type
strings I gave above are made-up; they could be something that maps to e.g.
XML schema types, if that's a suitable type system.
Notice too that this system can be self-expressing, e.g. via something like:
("http://schemas.osafoundation.org/EIM/typeInfo";, "typeURI", "URI")
("http://schemas.osafoundation.org/EIM/typeInfo";, "fieldName", "Text")
("http://schemas.osafoundation.org/EIM/typeInfo";, "fieldType", "TypeID")
But this meta-meta-information would be hardcoded rather than transmitted,
since it has to be fundamentally agreed upon in order to be able to
communicate at all. :)
With regard to the type system, it's possible for example that we might
have a separate set of records for types, e.g.:
("Text", "...XSD for the text type...")
("UUID", "...XSD for the UUID type...")
etc. (Again, if we want to use the XSD type system.)
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