My apologies for the Hibernate problems y'all have been having. We do have a bunch of users happily using this for relatively simple use cases but as your domain models grow in complexity, you may run into some problems.
Here are the set of problems I currently know about. 1) unique object exceptions during "updateItem". The one case where I know this will happen is if you have hibernate associations which do not have corresponding FDS associations (i.e. the hierarchical values). This should be supported and it turns out that the fix for the problem is to use hibernate's "merge" method instead of trying to do the merge by hand as is done in 2.0.1's updateItem method. The code in updateItem that is causing the bulk of this problem is the code which fetches the current server version to do conflict detection. In doing that, it creates hibernate instances in the session which may conflict with instances that get sent in by the client. Hibernate's "merge" method takes care of all of this for us. 2) Domain objects need id/equals test which is based on the id. Some of the code in the hibernate assembler is using the "equals" method when it should be comparing the id properties. You can workaround this by having equals and hashCode methods which are based on the id. 3) "Session closed" errors trying to fetch associations when we are writing objects to the client. I'm not sure why the current "fetchObjectProperties" method is not fetching these objects for some people's domain model but if anyone has a test case which can reproduce this I'm interested. It should be walking down all public properties and fetching them - the same way that our serialization code is working but somehow I must be missing something in the traversal code. There is a public beta coming out fairly soon which will have 1) and 2) fixed. I haven't had a chance to backport these fixes to a version of the hibernate assembler which works in 2.0.1 but if there is enough demand (and I can find enough time!) I could probably do that. Of course I'd rather get anyone running into trouble on the beta so we can make sure that version is solid. Jeff ________________________________ From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of simonjpalmer Sent: Friday, February 23, 2007 2:47 AM To: [email protected] Subject: [flexcoders] Re: FDS/Hibernate Sample of updating hierarchical list of values PW, BTW pop over to the FDS forum at Adobe http://www.adobe.com/cfusion/webforums/forum/categories.cfm?forumid=60&c atid=583 <http://www.adobe.com/cfusion/webforums/forum/categories.cfm?forumid=60&; catid=583> take a look at the thread called "Parent Child Hierarchy with FDS and Hibernate" SP --- In [email protected] <mailto:flexcoders%40yahoogroups.com> , "simonjpalmer" <[EMAIL PROTECTED]> wrote: > > PW and Jeff, > > PW, you and I seem to be in the same boat. I am trying to fight off > the people who were flex skeptics to start with. Not being able to > write data back makes the whole thing look pretty amateur and confirms > people's belief that the technology isn't ready - which given this > experience it clearly isn't. The baby is definitely at risk of being > thrown out with the bath water. It stands in our company simply > because I have the final call as Technical Director (CTO if you are in > the US). > > I am a huge flex advocate and really doing my best to evangelise on > the topic. What's more I think that the bridge to operational data is > the most profound leap forward for flash, it takes it out of the world > of gimicks and into the world of real business applications. > > Jeff, you and your and team deserve huge credit for that vision and > excellent execution. > > However, much as it pains me to say it, the bottom line is that the > hibernate middle tier provided does not work, as PW and I (and a host > of other people on various forums) have found. I know that I can > re-write the whole thing myself and will probably have to, but when > introducing new technologies it is unfortunately all about initial > perception. > > I have made a career of doing this sort of thing myself and I have > seen excellent projects fail to fly because of low initial quality, > even though we fixed them immediately, the damage was done because > people's impression was that they were flaky. I'm sure you know it is > hard to get back from that first impression and the word of mouth that > springs from it. Once it becomes entrenched that opinion becomes fact > and you are irrevocably lost. If I were Adobe I would be a little > worried about the tone of the posts I am seeing about integration with > Hibernate. > > The Hibernate Assembler is very important and I would really hate to > see that happen to it. The corollary is very unfortunate. That > little bit of technology transform the boardroom conversation about > FDS. Suddenly the cost of the licensing of FDS becomes justifiable > against the dev cost savings because we can just plug into the ORM. > Having made that justification myself it is very difficult for me now > to go back and say, "by the way I also have to incur the dev costs". > When asked why? I have to confess that the Adobe code doesn't work and > we don't know when we're getting a fix. For the Flex/Flash skeptics > in the room that's a god send. > > For me it is a complete nightmare. It is hard for me to separate the > cost of FDS licenses (which is almost prohibitively large) against the > cost of dev. I would urge Jeff and Co to get the Hibernate Assembler > code watertight and shipping asap. If I can be of any assistance I > will gladly offer my services. > > If either of you would like to contact me, post a reply and I will > happily give you my details. > > Simon Palmer > Technical Director > The PMCo > 62 St Peters Street > St Albans > HERTS AL1 3HG > UK > > --- In [email protected] <mailto:flexcoders%40yahoogroups.com> , "parkerwhirlow" <parkerwhirlow@> > wrote: > > > > Thats very unfortunate. I'm getting farther and farther into hot water > > not being able to reliably update our data model using Flex. > > > > Last it was "just wait for 2.0.1, there's a lot of Hibernate/FDS fixes > > in it" and now we're waiting for another unknown amount of time for > > fixes we can only hope will help our situation. > > > > I'm apologize, I understand it's not your fault, and I really > > appreciate the insight you provide as to what can be causing our > > problems, I'm just getting up to my neck in unsolved problems. > > > > If you have any insight as to "roughly" when this next release could > > occur, can you tip me off? > > > > thanks, > > PW > > > > --- In [email protected] <mailto:flexcoders%40yahoogroups.com> , "Jeff Vroom" <jvroom@> wrote: > > > > > > I have finished making the changes and the use of the "merge" call > seems > > > to be a) much simpler and b) more robust than the way the current code > > > works. > > > > > > > > > > > > Unfortunately we've made enough changes to the code surrounding the > > > HibernateAssembler so I can't just send you the updated file and > have it > > > work in FDS2. It will be in an upcoming public beta but I don't think > > > we've announced the dates on that. > > > > > > > > > > > > Jeff > > > > > > > > > > > > ________________________________ > > > > > > From: [email protected] <mailto:flexcoders%40yahoogroups.com> > [mailto:[email protected] <mailto:flexcoders%40yahoogroups.com> ] On > > > Behalf Of parkerwhirlow > > > Sent: Thursday, February 15, 2007 3:29 PM > > > To: [email protected] <mailto:flexcoders%40yahoogroups.com> > > > Subject: [flexcoders] Re: FDS/Hibernate Sample of updating > hierarchical > > > list of values > > > > > > > > > > > > Hey Jeff, just curious if you've got any updated HibernateAssembler > > > code with some fixes? Any idea when this would be available? > > > > > > thanks, > > > PW > > > > > > --- In [email protected] <mailto:flexcoders%40yahoogroups.com> > <mailto:flexcoders%40yahoogroups.com> > > > , "Jeff Vroom" <jvroom@> wrote: > > > > > > > > My apologies - this does look like a bug. I need to do more > testing on > > > > this case myself, but I think one of the big problems here is > that we > > > > are trying to do conflict detection on our own in the hibernate > > > > assembler's updateItem method. Unless you are using a strict > isolation > > > > level in your DB (repeatable read or serializable) this is not going > > > to > > > > be transactionally correct anyway since the DB version can be > modified > > > > after we have executed the query and before we do our update. We > > > > probably should not be getting the server version at all... > hibernate > > > > has its own optimistic concurrency support that we should be > using if > > > it > > > > is enabled. That is probably the only way to get atomic conflict > > > > detection without resorting to using those particularly slow > isolation > > > > levels. > > > > > > > > > > > > > > > > That would potentially get rid of the conflicting version of the > item > > > in > > > > the transaction. The other thing I need to look into is the "merge" > > > > method in hibernate. Seems like we should probably be using that in > > > the > > > > updateItem method? I'll be working on this next week so will > send out > > > > any updates I can to the code. > > > > > > > > > > > > > > > > Jeff > > > > > > > > > > > > > > > > ________________________________ > > > > > > > > From: [email protected] <mailto:flexcoders%40yahoogroups.com> > <mailto:flexcoders%40yahoogroups.com> > > > [mailto:[email protected] <mailto:flexcoders%40yahoogroups.com> > <mailto:flexcoders%40yahoogroups.com> > > > ] On > > > > Behalf Of parkerwhirlow > > > > Sent: Thursday, February 01, 2007 6:05 PM > > > > To: [email protected] <mailto:flexcoders%40yahoogroups.com> > <mailto:flexcoders%40yahoogroups.com> > > > > Subject: [flexcoders] FDS/Hibernate Sample of updating hierarchical > > > list > > > > of values > > > > > > > > > > > > > > > > > > > > Hi all, > > > > > > > > I have been tearing my hair out trying to get FDS/Hibernate to > update > > > > a hierarchical list of values. Even the simplest of collection > > > > mappings in Hibernate cause various exceptions when trying to > update. > > > > > > > > Before I post my details, does anyone have any examples of this that > > > > work? Has anyone ever even gotten this to work? > > > > > > > > I have two objects mapped in Hibernate: > > > > > > > > - Family > > > > ----Person > > > > > > > > where a Family has a Set of Person "familyMembers". > > > > > > > > My FDS destination is to Family, and I am trying to update a family > > > > member (just the name) through this destination. > > > > > > > > First, I was getting Hibernate NonUniqueObjectException, which I > > > > finally tracked down to having my hibernate collection mapping > set to > > > > lazy=false This caused all of the family member Person objects to be > > > > loaded into the PersistenceContext when the HibernateAssembler > loaded > > > > the "serverVersion" of the Family. > > > > > > > > Then, once I set lazy=true on the collection mapping, I was > getting an > > > > exception that "A collection with cascade="all-delete-orphan" was no > > > > longer referenced by the owning entity instance"... since it is > > > > assigning a whole new collection to the familyMembers property one > > > > becomes unreferenced, and the other referenced. Sooo I can't use > > > > delete orphan to delete the family members when the family is > > > > deleted... OK. So then I make cascade="all". > > > > > > > > Now I'm getting "ORA-01407: cannot update > > > > ("SCHEMA"."T_PERSON"."FAMILYID") to NULL"... I'm guessing that it's > > > > processing the dereferenced collection first (trying to detatch any > > > > Person's from the family before they're re-attached by the new > > > > collection. I can't believe this is so difficult... > > > > > > > > For more info on my setup and test case, please see my original > post: > > > > http://tech.groups.yahoo.com/group/flexcoders/message/63308 <http://tech.groups.yahoo.com/group/flexcoders/message/63308> > > > <http://tech.groups.yahoo.com/group/flexcoders/message/63308 <http://tech.groups.yahoo.com/group/flexcoders/message/63308> > > > > > <http://tech.groups.yahoo.com/group/flexcoders/message/63308 <http://tech.groups.yahoo.com/group/flexcoders/message/63308> > > > <http://tech.groups.yahoo.com/group/flexcoders/message/63308 <http://tech.groups.yahoo.com/group/flexcoders/message/63308> > > > > > > > > > > any comments as to if anyone has done this successfully are greatly > > > > appreciated! > > > > > > > > thanks, > > > > PW > > > > > > > > > >
