Anil Gangolli wrote:
+1 on the cleanup work in general. A big hoorah for the hierarchical
object cleanup!
I'd like to review the changes related to the persistence pattern so
that I understand them, but you can just let me know the commit
revisions involved.
I could do this on the wiki, but it seems easy and short enough to just
do it on the list. So, the most fundamental change is that the
folderassoc and weblogcategoryassoc db tables are not used anymore, and
the HierarchicalPO, Assoc, WeblogCategoryAssoc, and FolderAssoc classes
are all being deleted along with any methods and code which referenced them.
I'll just detail the weblog category example since it's the same for
folders. So we are going to add a single column 'parentid' to the
weblogcategory table which means the table will look like ...
create table weblogcategory (
id varchar(48) not null primary key,
name varchar(255) not null,
description varchar(255),
websiteid varchar(48) not null,
image varchar(255),
parentid varchar(48)
);
By doing that there are 2 significant changes in the pojo because we can
now directly reference the parent and children of a category using
simple hibernate mappings ...
/**
* @hibernate.many-to-one column="parentid" cascade="none"
not-null="false"
*/
public WeblogCategoryData getParent() {
return this.parentCategory;
}
/**
* @hibernate.set lazy="true" inverse="true" cascade="delete"
* @hibernate.collection-key column="parentid"
* @hibernate.collection-one-to-many
class="org.apache.roller.pojos.WeblogCategoryData"
*/
public Set getWeblogCategories() {
return this.childCategories;
}
So as you can see, the parent of a given category is a simply
many-to-one association and of course for the root node the parent is
NULL. Then for the child nodes it's a typical one-to-many association
which simply points back to the same table and is basically formed by
querying for all categories which list the current object as it's parent.
That basically sums up all the changes as far as associations are
concerned and provides an easy way to walk the tree. The funny thing
was that many of the other methods which I thought would have needed
more tweaking to work with these changes didn't really need much
changing at all. Methods like retrieveEntries() or getPath() were
already being formed by simply walking the tree and compiling the
objects, so they didn't change too much at all.
If we make these changes, it's good to do it early in the release cycle
(as soon as 3.1 is branched off of main) so they get some road time in
development before we release.
definitely.
It's not unlikely that we will break some things temporarily and not
notice it for a while. The riskiest aspect to me in this regard is lazy
fetching because it really demands that the session span the entire
request, which we seemed to have a hard time doing properly earlier, and
I'm not sure exactly why. We backed out of lazy fetching just before
one release a ways back because we would hit odd session closed
exceptions that we didn't have time to figure out. It's possible that
some of Allen's earlier session management cleanups already got us out
of those issues. It's a good idea to revisit this now. I think that is
also likely to make us more portable to optimizations in other
persistence implementations that expect essentially the same session
management pattern.
so far I have been able to make all the changes that I think are correct
and I have all the unit tests running correctly, so what I am doing now
is going over the actual webapp and running through all the operations
that I can to find and fix anything that I find. Things are definitely
cropping up, but so far the lazy initialization problem hasn't come up.
The bigger problem has been caused by changing the hibernate config to
use FlushMode.NEVER, which means that hibernate doesn't flush its state
to the db until we explicitly call the flush() method on the Session.
As it turns out, a *lot* of the stuff we were doing has been very
reliant on auto flushing for it to work, so there have been a handful of
places where I have had to figure out how to fix that problem. So far
so good though, and I hope to have things cleaned up enough to commit in
the next day or so.
-- Allen
--a.
----- Original Message ----- From: "Allen Gilliland"
<[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, November 13, 2006 4:46 PM
Subject: Re: Business layer cleanup for 3.2
certainly. I didn't do much in the way of renaming things yet, the
first pass was mainly about fixing up the Hibernate config to work the
way I think it should have been working and clearing out some things
along the way. Once that is done then I plan to go over the business
layer more times and find places where methods should be renamed,
removed, or consolidated in any way. I also want to keep building on
the unit tests because I think they are pretty good now, but there are
a few gaps here and there.
At the end of the day this work will definitely help to make the work
on the JDO/JPA backends quite a bit easier.
-- Allen
Craig L Russell wrote:
Hi Allen,
We had discussed a number of issues with the manager classes such as
misspelled method names and incomplete functionality (having the
caller iterate through collections).
I'd be happy to review what you've done in terms of cleanup.
Regards,
Craig
On Nov 13, 2006, at 2:10 PM, Allen Gilliland wrote:
One of the things that I am planning to do for the 3.2 release is do
some audit/cleanup of the current business layer code. There are a
variety of things which could use improving, but the main goal is to
fix our Hibernate configuration so that we are 1) properly using the
open session in view pattern and 2) enabling lazy fetching on all
objects and associations.
Right now our Hibernate config is pretty messy and doesn't take
advantage of many of Hibernate's performance features, so the main
reason to do this work is to improve the performance of the business
layer. The second big reason is just to reduce clutter and simplify
the code as much as possible. There are plenty of places in the
code where we have methods that aren't used at all or methods which
are duplicated, so those would all be cleaned up.
I have most of this work done already (but not checked in) and there
aren't really any surprise changes that I had to make except when it
came to the hierarchical objects. I tried for multiple days to get
the hierarchical objects to work with the updated hibernate config
and the current data model, but I kept running into problems. So to
fix the problem I had to make a small tweak to the way hierarchical
objects are persisted which fixed my issues and I believe
drastically simplifies the problem overall. The basic change is
that I have completely removed the HierarchicalPersistentObject
class and Assoc and it's subclasses and changed the data model so
that we have a more normal hierarchical model.
So, for weblog categories I added a simple 'parentid' column to the
weblogcategory table and that allows a category to manage
relationships between it's parent and children directly. Same goes
for the FolderData class, but as it turns out that column already
existed in the schema but wasn't being used. Upgrade path for both
of these is fairly simple and only requires populating these columns
with the right value.
I'm not sure if anyone really wants to see more of a proposal for
this, which is why I started with an adhoc description here on the
list. As I said, I am not actually modifying anything from a
feature point of view, only cleaning up what is already there. If
anyone wants to see more about the changes to the hierarchical
objects then I can post them on the wiki or something.
-- Allen
Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:[EMAIL PROTECTED]
P.S. A good JDO? O, Gasp!
