Hi all!
Looks nice and simple. A colleague of mine at Mindquarry did a jcr-
persistence framework that is very, very similar to JPA. I can't
remember why he did not use it directly, so he recreated the basic
annotation classes like Entity, ID or NamedQuery. Probably because you
need some special jcr-compatible extensions.
Here is an example [4] which would map to /users/*. Note the
parentFolder setting of @Entity and also that querying is just like in
JPA, but using XPath instead:
@SerializationName("user")
@Entity(parentFolder=User.PARENT_FOLDER)
@NamedQueries({
@NamedQuery(name="userByLogin", query="/users/{$userId}"),
@NamedQuery(name="allUsers", query="/users/*[local-name() !=
'photos']"),
@NamedQuery(name="getUsersForTeam", query="/users/*[jcr:content/
user/teams/item/@reference = /teamspaces/{$teamId}/@jcr:uuid]")
})
public class User {
public static final String PARENT_FOLDER = "users";
@Id
private String login = "";
private String pwd = "";
public String firstname = "";
public String lastname = "";
private List<String> skills;
private String[] skillsArray;
private List<Team> teams;
public Group group;
.....
}
Example of creating/querying objects:
Team team = makeTestTeam(); // new Team() + setting values
currentSession().persist(team);
List<Team> teams = new LinkedList<Team>();
teams.add(team);
User user = makeTestUser(); // new User() + setting values
user.setTeams(teams);
currentSession().persist(user);
Session session = sessionFactory_.currentSession();
List<Object> queryResult = session.query("getUsersForTeam",
TEST_TEAM_ID);
assertEquals(1, queryResult.size());
See the framework [1], API classes (eg. Entity) at [2], and the test
code for more samples [3]. Note that there is no documentation online
apart from the code.
The implemenation allows for reading/writing full object graphs, ie. a
field in an object referencing another object that is also mapped to
JCR would get read/written along the way (storing only the object Id
in JCR, but preferable would be the JCR path of the referenced
object). The JCR structure was custom (it was XMLish, as we stored XML
documents directly in a different part of the code), but a Transformer
interface abstracts from the special Java <-> JCR mapping [5].
In the end, we were not so happy with this approach because it seemed
to much abstraction from our main API JCR and created yet another
caching location (the managed object pool). But we probably added too
much abstraction (fully JCR-independent interfaces that were
implemented by the annotated objects, yet another Session class,
etc.)...
Here is the executive summary of the pros and cons (which you probably
know from OCM or JCROM):
Advantages:
+ full object graphs supported
+ easy-to-run queries, defined at the object itself
+ code completion for properties
Disadvantages:
- pooling = caching needed
- another hard-to-debug abstraction
- just a copy of JPA, not using it directly
Regards,
Alex
[1]
http://www.mindquarry.org/repos/mindquarry-collaboration-server/trunk/mindquarry-persistence/
[2] API:
http://www.mindquarry.org/repos/mindquarry-collaboration-server/trunk/mindquarry-persistence/persistence-api/src/main/java/com/mindquarry/persistence/api/
[3] Test code:
http://www.mindquarry.org/repos/mindquarry-collaboration-server/trunk/mindquarry-persistence/jcr-persistence/src/test/java/com/mindquarry/persistence/jcr/
[4] Example annotated class:
http://www.mindquarry.org/repos/mindquarry-collaboration-server/trunk/mindquarry-persistence/jcr-persistence/src/test/java/com/mindquarry/persistence/jcr/User.java
[5] "Transformers", mapping Java <-> JCR:
http://www.mindquarry.org/repos/mindquarry-collaboration-server/trunk/mindquarry-persistence/jcr-persistence/src/main/java/com/mindquarry/persistence/jcr/trafo/
Am 05.02.2008 um 12:48 schrieb David Nuescheler:
hi all,
Olafur Gauti Gudmundsson pointed me today to his effort called JCROM
(pronounced "Jack-rom"). [1]
I am excited about the refreshing, quick and simple annotation based
approach [2]
and would like to find out what everybody's thoughts are on possibly
finding synergies
with the ocm framework that we have in Jackrabbit.
regards,
david
[1] http://jcrom.org
[2] http://code.google.com/p/jcrom/wiki/TwoMinuteIntro
--
Alexander Klimetschek
[EMAIL PROTECTED]
