On May 26, 2006, at 4:45 PM, Craig L Russell wrote:
By the way, feel free to engage the roller alias on this thread.
A-OK. Here goes.
On May 26, 2006, at 12:00 PM, Dave Johnson wrote:
On May 26, 2006, at 2:41 PM, Craig L Russell wrote:
Hi Dave, Thanks for the doc.
I plan to add implementations that can be shared between JDO and
EJB3 to implement the Roller interfaces. When I look at the
Hibernate implementations, there is about 80% overlap with what
JDO needs.
Can you briefly explain what parts are overlapping?
For example,
public HibernateAutoPingManagerImpl
(HibernatePersistenceStrategy strat) {
this.strategy = strat;
}
public AutoPingData getAutoPing(String id) throws
RollerException {
return (AutoPingData) strategy.load(id, AutoPingData.class);
}
public void saveAutoPing(AutoPingData autoPing) throws
RollerException {
strategy.store(autoPing);
}
public void removeAutoPing(AutoPingData autoPing) throws
RollerException {
//TODO: first remove all related category restrictions
(category restrictions are not yet implemented)
strategy.remove(autoPing);
}
public void removeAutoPings(Collection autopings) throws
RollerException {
// just go through the list and remove each auto ping
Iterator pings = autopings.iterator();
while (pings.hasNext()) {
this.strategy.remove((AutoPingData) pings.next());
}
}
public void removeAllAutoPings() throws RollerException {
try {
Session session = ((HibernatePersistenceStrategy)
strategy).getSession();
Criteria criteria = session.createCriteria
(AutoPingData.class);
List allAutoPings = criteria.list();
this.removeAutoPings(allAutoPings);
} catch (HibernateException e) {
throw new RollerException(e);
}
}
public void queueApplicableAutoPings(WeblogEntryData
changedWeblogEntry) throws RollerException {
if (PingConfig.getSuspendPingProcessing()) {
if (log.isDebugEnabled()) log.debug("Ping processing is
suspended. No auto pings will be queued.");
return;
}
// TODO: new manager method for addQueueEntries(list)?
PingQueueManager pingQueueMgr = RollerFactory.getRoller
().getPingQueueManager();
List applicableAutopings = getApplicableAutoPings
(changedWeblogEntry);
for (Iterator i = applicableAutopings.iterator(); i.hasNext
(); ) {
AutoPingData autoPing = (AutoPingData) i.next();
pingQueueMgr.addQueueEntry(autoPing);
}
}
public List getAutoPingsByWebsite(WebsiteData website) throws
RollerException {
try {
Session session = ((HibernatePersistenceStrategy)
strategy).getSession();
Criteria criteria = session.createCriteria
(AutoPingData.class);
// Currently category restrictions are not yet
implemented, so we return all auto ping configs for the
// website.
criteria.add(Expression.eq("website", website));
return criteria.list();
} catch (HibernateException e) {
throw new RollerException(e);
}
}
public List getAutoPingsByTarget(PingTargetData pingTarget)
throws RollerException {
try {
Session session = ((HibernatePersistenceStrategy)
strategy).getSession();
Criteria criteria = session.createCriteria
(AutoPingData.class);
// Currently category restrictions are not yet
implemented, so we return all auto ping configs for the
// website.
criteria.add(Expression.eq("pingTarget", pingTarget));
return criteria.list();
} catch (HibernateException e) {
throw new RollerException(e);
}
}
public List getCategoryRestrictions(AutoPingData autoPing)
throws RollerException {
return Collections.EMPTY_LIST;
}
public void setCategoryRestrictions(AutoPingData autoPing,
Collection newCategories) {
// NOT YET IMPLEMENTED
return;
}
public void release() {}
The only parts of the Hibernate implementation that are Hibernate-
specific have to do with the criteria queries, which will require a
criteria API in the JDO/Hibernate/EJB3 implementation.
You know, I wrote a complete criteria query API back in the 0.9.9
code base and an implementation for Castor-JDO (which generated OQL)
and Hibernate (which generated HSQL). We had it in production at
JRoller.com for a while, but we dropped it when we completely dropped
Castor-JDO support (code is here -> http://tinyurl.com/k7lgm).
Cool idea, but I must admit that I'm a little concerned about
maintaining a criteria API infrastructure in Roller. Seems like a
criteria API should be part of JDO and/or JPA instead.
Are you proposing to implement the Hibernate Criteria API verbatim or
something new?
So it looks like the best solution is to add a package datamapper
and add concrete classes, e.g. DatamapperAutoPingManagerImpl that
delegates to a DatamapperPersistenceManager that handles the
abstraction to the specific persistence layer.
Could you expand on that a little. What does the
DatamapperPersistenceManager do? Does it handle persistence and
queries for all Roller POJOs?
The DatamapperPersistenceManager would have methods similar to the
HibernatePersistenceStrategy: flush(), release(), load(), store(),
remove(). It would also have criteria query support that allows
queries based on fields and values, e.g.
Criteria criteria = session.createCriteria
(AutoPingData.class);
// Currently category restrictions are not yet
implemented, so we
// return all auto ping configs for the website.
criteria.add(Expression.eq("pingTarget", pingTarget));
criteria.add(Expression.eq("website", website));
List matches = criteria.list();
We would abstract this to allow passing the criteria Expression.eq
("pingTarget", pingTarget) as a parameter to the
DatamapperPersistenceManager. Or we subclass the
DatamapperAutoPingManagerImpl. We will have to look at the details.
This way, the only code specific to EJB3 or JDO would be the
implementation of DatamapperPersistenceManager and Roller
interfaces.
So, the JDO specific parts of the implementation would be confined
to two classes? That sounds too good to be true.
Of course it's too good to be true. But that's the objective.
OK, I understand now. It might be good to come up with a brief
proposal on the wiki that outlines the design. I'd be glad to help
with that.
And, instead of working in the sandbox, how about we make a new
branch for this work. That might be easier for us all.
- Dave
