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Are Hibernate Annotations supported?

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Level 1
Does FDS support Hibernate annotations? Will the use of
hibernate annotations create any problems?



-hc
0 Replies

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Level 3
Hi HC,



I haven't had a chance to play with Hibernate's new
annotation support which isn't final yet, but the FDS Hibernate
assembler doesn't have any direct dependence on where your entity
mappings are defined. It needs the location of your core Hibernate
config file and that's it; all other info it uses is obtained from
a corresponding Hibernate Configuration object. So my guess is that
using annotations for your mappings should "just work" 😉



When using the Hibernate assembler you still need to define
association relationships between your data service destinations.
These are not automatically created based on existing Hibernate
entity mappings.



Post back if you get a chance to try this out. I'll add it to
my queue of things to investigate.



Regards,

Seth

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Not applicable
Unfortunately the session is builded by using an
org.hibernate.cfg.AnnotationConfiguration but the
HibernateAssembler only uses org.hibernate.cfg.Configuration.

So I extended the HibernateAssembler to use a
AnnotationConfiguration and also changed the source of the
destination to my Assembler in the 'data-management-config.xml'.
The hibernate.cfg.xml and both Employee.java and Company.java of
the hibernate fds-sample 'crm' (tested with another tool) are
adapted to hibernate 3 annotations. but all i got is the error
message:



faultCode=Client.Error.Message.Send

faultDetail=Channel.Connect.Failled error null

code=NetConnection.Connect.Failed



Google and Adobe told me this is an hibernate.cfg.xml-error
but i do not believe so because using the same files by
implementing a simple testcase is working and connecting
successfully.

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Level 2
You are charting new ground using hibernate annotations but
it sounds like your approach is the right one. The error you are
getting now is a general one which happens when an uncaught
exception occurs on the server. The best way to diagnose that is to
turn on Debug logging on the server (edit
WEB-INF/flex/services-config.xml, search for level= and change that
attribute to Debug. Make sure that your <patterns> tags below
have both Message.* and DataService.*. You should see the stack
trace and detailed error on what caused the exception and that
would help us determine what is going on. I'd be happy to help get
this to work - this is an important use case.

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Level 3
Hi Pete,



That error indicates that your client app is not able to
establish a connection to the server. I'd recommend using
<mx:TraceTarget/> to enable client side debug output to
flashlog.txt and take a look there to see which channel is failing
to connect and what the underlying root cause is.



Common reasons for this are invalid or out of date channel
endpoint URIs or a {context.root} token in a channel URI not being
replaced at compile time with the true value (use the
-compiler.context-root mxmlc option).



If your simple test case is working, once you've got the
connection problem between the client and server sorted out you
should be in good shape.



Best,

Seth

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Level 2
We have the JBoss implementation of EJB 3.0 working with
Flex. The JBoss implementation of EJB 3.0 is really hibernate
annotations... In this configuration, Flex does not need to talk
directly to Hibernate, and we have the full power of the new EJB
3.0 Annotations (beyond the support and features provided in the
HibernateAdapter). Our Assemblers use JNDI to access session beans
which work with the entity beans.



One huge problem with Flex however is that due to the
relationships between objects in the ORM, combined with FDS's
desire to access each public property, the
LazyInitializationException rears it's ugly head every time a lazy
association property is traversed.



We desparately need FDS to recognize the proxy object for
what it is - a land mine waiting to go off should the property be
touched once outside the transaction which has already been closed
(inside the serialization process to AMF or RTMP).



We currently intercept the calls to null out proxy objects
after the transaction is closed but before FDS has a chance to set
off the land mine, and this works for the most part. However, not
being able to take advantage of lazy initialization causes a lot
more data to be sent back and forth.



I would really encourage a change of FDS serialization code
to watch for the common objects used to represent the existance of
a proxy within the common ORM solutions, and jump over them when
building the object graph. It's an essential part of an application
in an ORM environment.

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Level 1
Please keep this thread going!! This use case is central to
our companies strategy and the documentation / material out there
for "the rest of us" is non-existant.



Pete / Seth / jvroom, have you got any further in your
research on this? Would you be willing to elaborate on findings? I
would very much like to pursue getting this to work.



Stupid question #1: When did you get the source for the
HibernateAssembler class? I cannot seem to locate it.



busitech, I am not sure I follow you completely. If I
understand correctly, your flex app points to the destination which
is using your own custom assembler and loads the session beans (via
JNDI lookup) essentially as delegates to the entity beans in place
of the actual entity beans? Would you be willing to share some of
your insights as to how you got this working? Any documentation /
reference material would be helpful.



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Level 2
This thread was started by hchafi to discuss using the
HibernateAdapter to reach the goal of using Hibernate Annotations.



I introduced a different approach to achieve the same goal by
AVOIDING the HibernateAdapter (becuase it only supports CRUD
methods and requires 100% of your business logic to be written in
actionscript on the client).



bjk0002, I am not sure which method you are truly interested
in. For my approach, the documentation is out there. I would
suggest your starting point be reading the JavaDoc supplied in your
FDS install directory for the
flex.data.assemblers.AbstractAssembler class.



Actually, HibernateAssember is also an example of my approach
because it is a custom assembler extending the above class
(AbstactAssembler).



The source for HibernateAssembler is in
C:\fds2\resources\samples\assemblers