FAQ
Hi Cayenne users,

the issue in the subject is being currently discussed by Cayenne developers (see the message from dev below). Anybody's using XML serialization now? If so I'd like to hear how you deal with all the deficiencies of this package?

Thanks,
Andrus



Begin forwarded message:
To: dev@cayenne.apache.org
Subject: deprecate XML package in 3.1

I suggest to deprecate XML serialization package in 3.1 and remove it in 3.2. There were past discussions why it is not a working solution for real life applications (DOM, singletons, etc.). Also real life serialization/deserialization patterns are different from what we provide there (at least I couldn't adopt it to any of my own needs). And finally there's nobody around willing to address these deficiencies.

Some time back I started on an alternative serialization package, currently checked in to sandbox:

http://svn.apache.org/repos/asf/cayenne/sandbox/cayenne-serialization/

It uses XStream and is based on an idea similar to ROP - serialization specification is defined like to prefetches in a select query - there's a root entity, and there's a bunch of prefetch paths for related objects that need to be serialized together with the root objects. It works, but has some of rough edges and missing features. Also would be really cool to port that to JAXB, as JAXB is a part of J2SE these days. As I won't be able to work on this any time soon, it requires other motivated individuals to make it production-ready.

In any event I don't see a point in keeping the existing XML package regardless of the outcome of the replacement, and would like to phase it out.

Andrus

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  • Adrian Wiesmann at Dec 4, 2010 at 3:08 pm
    Hi there
    the issue in the subject is being currently discussed by Cayenne developers (see the message from dev below). Anybody's using XML serialization now? If so I'd like to hear how you deal with all the deficiencies of this package?
    Yes, actually both, serialisation and deserialisation. We thought it is
    a nice way to have snapshot files. A snapshot file is just a zipped
    container containing a manifest file and one or multiple files
    containing data. One table represents a single file, XML formatted.

    Since all our tables have UUID as primary keys snapshot files make it
    possible to allow road warriors to easily take data on the road and
    later check it back into the main database...

    It is quite convenient to have some support from Cayenne for this.

    Cheers,
    Adrian
  • Andrus Adamchik at Jan 11, 2011 at 11:42 am
    Hi Adrian,

    Sorry for a belated reply and thanks for describing your XML serialization scenario. I think it sorta proves my point that current serialization framework only works in very special cases (e.g. in your case we have a single entity per serialization run, no handling of relationships, and no real-time performance requirements). And this particular special case is fairly straightforward to build from scratch.

    Cheers,
    Andrus


    On Dec 4, 2010, at 5:08 PM, Adrian Wiesmann wrote:
    Hi there
    the issue in the subject is being currently discussed by Cayenne developers (see the message from dev below). Anybody's using XML serialization now? If so I'd like to hear how you deal with all the deficiencies of this package?
    Yes, actually both, serialisation and deserialisation. We thought it is a nice way to have snapshot files. A snapshot file is just a zipped container containing a manifest file and one or multiple files containing data. One table represents a single file, XML formatted.

    Since all our tables have UUID as primary keys snapshot files make it possible to allow road warriors to easily take data on the road and later check it back into the main database...

    It is quite convenient to have some support from Cayenne for this.

    Cheers,
    Adrian

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