BlazeDS + Spring + Transactions: LazyInitializationException

Question

My question is how to specify that a RemoteObject method call should participate in a JPA transaction.
I have Spring + BlazeDS + Hibernate running in Tomcat. I have a remoting destination, call it userService, setup to point to a spring bean. The userService has a "getUsers" method, which is annotated with @Transactional.
Each of the users returned in the list has another collection, properties, that is lazily loaded. Since it is lazily loaded it does not get initialized in the getUsers method call. Instead, it gets initialized when BlazeDS tries to serialize the object. At that point, I get a LazyInitializationException.
I don't want to mark all calls to /messagebroker/ as transactional, nor do i want to initialize all potentially lazy properties of each user object.
What do people recommend? I wonder if there is a way to provide plugin filters for BlazeDS method invocations so that I could write a filter that figured out if a call required a transaction.
Thanks
/r

Answer 1

mido,<br /><br />you've got it and it's tedious.  i have not tried any of the<br />frameworks you've used.  i have found that for the great majority of<br />service calls i can get away with 1 to 3 assemblers.   you could also<br />"configure" your assembler instead of using separate ones.  for<br />example, i could have a property in one assembler that says<br />"getChildren == [boolean]". if true, then it gets the children, if<br />not, then no.<br /><br />it's still a tedious approach and, yes, the limitation with the<br />externalizable interface is the inability to serialize the item in two<br />different ways.<br /><br />unfortunately, i don't have much more to add to it.  one thing i've<br />found, tho, is that I at first don't worry about using the<br />dto/assember approach until i really need to.  it's more important to<br />get into a quick turnaround on the code/compile/test cycle.  then when<br />I run into bottlenecks, like the message and its replies problem, i go<br />ahead and apply the assembler approach.   once you have that assembler<br />solid, however, you might not have to change it much.<br /><br />best of luck.<br /><br />/r<br /><br /><br /><br /><br />On Wed, Jun 11, 2008 at 9:10 AM, mido <[email protected]> wrote:<br />> A new message was posted by mido in<br />><br />> General Discussion --<br />>   BlazeDS + Spring + Transactions: LazyInitializationException<br />><br />> Hi Robert,<br />><br />> It does indeed. Sorry to insist, but I still have few doubts in my mind.<br />> Let's take your getThread service function. This service is defined in your<br />> server side. In it, you assemble all the elements you want (from the<br />> hibernate bean and its children, children's children , etc...), and populate<br />> a MessageDTO bean. This is the object that gets returned to the client.<br />> Then, in the client you consume that bean, via probably a MessageVO that<br />> corresponds to the MessageDTO Bean. The MessageVO gets updated, etc...and<br />> then comes the time to update the server. The MessageVO gets serialized back<br />> to the server in a MessageDTO bean, which then gets de-assembled into your<br />> your hibernate bean/beans which then finally get persisted.<br />> It just sounds tedious to me...For every "view" in your client you have to<br />> create the DTO on the server, the corresponding VO on the client, an<br />> assembler/de-assembler set, a service and edit the config files....<br />><br />> Are you using any framework/code generator/ or did you come up with your own<br />> little framework?<br />><br />> I have researched a bit the web and I found couple of those generators.<br />> These looked interesting and I thought I'd share them in case you haven't<br />> seen them:<br />> - http://www.faratasystems.com/download/daoFlex/welcome.html (looks good)<br />> - http://amfibian.sourceforge.net./?page=home<br />> - http://hibernate4gwt.sourceforge.net/index.html<br />><br />> They are all based on annotations/ant....<br />><br />> For now, what I have been doing is using the externalizable interface and<br />> serializing my objects as I go....but the obvious limitation to that, is<br />> that I can serialize the same object in 2 different ways...to meet two<br />> different services on the client, based on the same hibernate object....so<br />> sooner or later, I will have to jump into the DTO approach....<br />><br />> Cheers,<br />> Thank you again,<br />><br />> ________________________________<br />> View/reply at BlazeDS + Spring + Transactions: LazyInitializationException<br />> Replies by email are OK.<br />> Use the unsubscribe form to cancel your email subscription.<br />><br />><br /><br /><br /><br />-- <br />Robert Cadena<br />CTO, SearchCoders<br />http://www.searchcoders.com/<br />http://www.chatopica.com/<br />skype: searchcoders