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Date: Tue, 16 Jan 2007 02:16:19 +0200
From: Ilan Kirsh <kirsh@objectdb.com>
Subject: Thoughts about JDO 2.1 Annotation
To: jdo-dev@db.apache.org, JDO Expert Group <jdo-experts-ext@Sun.COM>
Reply-to: Ilan Kirsh <kirsh@objectdb.com>
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Hi all,

I just added Java 5.0 annotation support to ObjectDB, following the work =
that was contributed by Andy =
(http://issues.apache.org/jira/browse/JDO-403).
Andy did a great job, but still there might be a little room for =
improvements. Following are suggestions that might be considered.

1. Using simple annotations instead of complex attributes
For instance:
    @PrimaryKey
instead of:
    @Field(primaryKey=3Dtrue)
(or simply @Id as in JPA).

And another example:
    @Embedded / @Embedded(false)
Instead of:
    @Field(embedded=3D"true") / @Field(embedded=3D"false")
which also solves the need to use boolean as string in order to get a =
third state, which doesn't look good.

This could be done at least for the more common attributes.

Also, maybe @Index should be defined without unique option, by:
    public @interface Indexed { boolean value() default true; }
or maybe even by:
    public @interface Unique {}
and simply used with:
    @Indexed
Do we really need so many different methods to define a unique index?

2. Discarding @Array, @Collection and @Map
It seems logical to move the attributes of @Array, @Collection and @Map =
to @Element, @Key and @Value. The separation (whose origin is in the =
XML) is unclear to me.

3. Merging all annotations to one package
Good separation seems to be very difficult. For instance - @Index, which =
is currently in orm has both columns and fields as attributes. Fields =
are not related to orm - just columns. If the separation remains, at =
least moving @Index, @Indices, @Unique, @Uniques, @Element, @Key and =
@Value that contain also non orm information should be pulled out to the =
main package.

4. Type attributes should be Class rather than String
For instance, in Field:
    Class fieldType();
instead of:
    String fieldType() default "";

5. RecursionDepth
Should be added somehow to the fields in @FetchGroup (and removed from =
@Field if unused).

Regards,

Ilan Kirsh
ObjectDB Software
http://www.objectdb.com
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