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From "Patrick Linskey" <>
Subject Re: Preliminary design for supporting OpenJPA annotations in XML metadata.
Date Wed, 25 Jul 2007 00:03:57 GMT
I haven't read David and Marc's most recent emails, but here's an idea
that I've been toying with in terms of unifying annotation and XML
parsing: annotations are interfaces, so presumably we can create new
instances of types that implement them somehow. (Maybe the JVM
prevents this; I haven't tested.) If so, then we could just have a
single annotation parser, and have the XML parser generate annotations
to pipe into the annotation parser.

I'm not sure if that gets us anything, but it might be an interesting
direction to explore.


On 7/20/07, David Ezzio (asmtp) <> wrote:
> Hi,
> I'm starting to design support of XML metadata for OpenJPA annotations
> in order to address OpenJPA-125 and OpenJPA-87.
> I've attached a zip containing a preliminary design document, a sample
> openjpa_orm_1_0.xsd file and a sample OpenJPA ORM instance.
> It took quite a while to create the text document and it is best viewed
> as the tracks of a design process.  The design that I worked on the most
> (the one with the most documentation) is not necessarily the best
> design.  There are two alternatives suggested, and there may be others
> that I haven't thought of.
> I think the fundamental choices facing us are these:
> 1. Do we construct an OpenJPA ORM schema that extends the JPA ORM
> schema?  Doing so, allows the user to use one metadata file instead of
> two, and will enhance maintainability for our users' applications.  Or
> do we construct a standalone OpenJPA ORM schema?  I've chosen the first
> option in the preliminary design, and I think it is the best choice.
> 2. Do we use a syntactically loose "extension" element format or do we
> construct new elements for each supported annotation?  Choosing the
> first makes it easy (I think) to support newly added annotations.
> Choosing the second allows the schema validator to do most of the
> validation work.  I've chosen the first option in the preliminary
> design, but I'm not at all sure of the choice.
> 3. Do we envision support in XML for all OpenJPA annotations or for only
> a subset?  If a subset, how do we draw a bright line that will be
> consistent and easily documented and followed over time?  I've chosen
> the first option in the preliminary design simply because that is the
> brightest line that I can think of and because it gave me a chance to
> look over the field of OpenJPA annotations.
> I'll be off on vacation for a week with very limited Internet
> connections, so please, take as much time as necessary to consider the
> design, and carry on some discussions without me if the spirit moves you.
> Thanks,
> David Ezzio

Patrick Linskey
202 669 5907

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