Hi Ruben,
I think this is handled quite nicely by XmlBeans, within the
context set
by the XMLSchema spec. Assuming you have a
backwards-compatible Schema
on the server and an older version of that on the client you
can either
have extra elements sent by the server, which will of course
be
inaccessible via the generated APIs that the client uses,
but they will
be accessible by the XmlCursor API. Or you could have
restriction, when
the server will stop sending elements/attributes that were
optional
anyway. The client still works. On the server, it's a little
trickier
but still works and the server may even choose to support
clients with
older Schemas specifically, for instance by using XmlCursor
to get to
information that was removed from the most current version
of the Schema
using restriction, but the clients are still sending.
Onto the problem of "discovery", XmlBeans saves
Schema information along
with generated classes in the jar. So if a client will call
"validate"
for instance, it will validate against the version of Schema
that the
client has, even though the document may be generated using
a different
version of the Schema. I am not sure I understand what you
mean by
"Ignore everything you know!": as long as the
client uses at runtime the
same version of the Schema that the client code was written
against, the
server does the same, the two Schemas are
backwards-compatible and the
message on the wire is "pure" XML if you will,
then everything should
hang together.
Hope this helps,
Radu
-----Original Message-----
From: Ruben Verlinden [mailto:rverlind vub.ac.be]
Sent: Thursday, October 05, 2006 9:05 AM
To: userxmlbeans.apache.org
Subject: Re: XML Schema evolution forward and backwards
compatibility
On Thu, 2006-10-05 at 08:33 -0700, Martin Wegner wrote:
>
> The issue has less to do with XMLBeans and more with
the XML Schema
> standard itself. It is hard to do. I would suggest
you start reading
> here:
>
>
> http://www.pacificspirit.com/Authoring/Com
patibility/ProvidingCompatib
> leSchemaEvolution.html
>
I already had a look at this article. The problem is how to
support XML
schema discovery (which is the XML schema for a certain
document) and
doing the projection if possible with XMLBeans.
kind regards,
Ruben
> ----- Original Message ----
> From: Ruben Verlinden <rverlindvub.ac.be>
> To: userxmlbeans.apache.org
> Sent: Wednesday, October 4, 2006 10:42:35 AM
> Subject: XML Schema evolution forward and backwards
compatibility
>
> Hello,
> I am new to using XMLBeans and I wonder if somebody can
provide me
> with some insights on supporting backward/forward
compatibility after
> the XML Schema for a certain document type evolves
using XMLBeans.
>
> The general idea was to have clients which only support
an older
> version of the schema than the documents sent by the
server to do a
> projection of the XML document to their known schema.
Which comes down
> to: Ignore everything you know! Possibly a must not
ignore could be
> built into some elements later on.
>
> The server should also be able to receive XML documents
that follow an
> older schema than the one used on the server. When
receiving such a
> XML document the server should parse it an decide if it
can find
> enough information in the document or not.
>
>
> Can anyone provide me some insight on how to do this
using XMLBeans?
> Or
> if XMLBeans is even suited for this kind of task?
>
>
> kind regards,
> Ruben Verlinden
>
>
>
------------------------------------------------------------
---------
> To unsubscribe, e-mail: user-unsubscribexmlbeans.apache.org
> For additional commands, e-mail: user-helpxmlbeans.apache.org
>
>
>
>
------------------------------------------------------------
---------
To unsubscribe, e-mail: user-unsubscribexmlbeans.apache.org
For additional commands, e-mail: user-helpxmlbeans.apache.org
____________________________________________________________
___________
Notice: This email message, together with any attachments,
may contain
information of BEA Systems, Inc., its subsidiaries and
affiliated
entities, that may be confidential, proprietary,
copyrighted and/or
legally privileged, and is intended solely for the use of
the individual
or entity named in this message. If you are not the intended
recipient,
and have received this message in error, please immediately
return this
by email and then delete it.
------------------------------------------------------------
---------
To unsubscribe, e-mail: user-unsubscribexmlbeans.apache.org
For additional commands, e-mail: user-helpxmlbeans.apache.org
|