In Aries JPA 2.1.0 it was possible to colocate the persistence unit and
the impl using the EntityManager.
The reason is that in that version the EntityManager service is simply
accessed using plain OSGi API. So the blueprint startup is not waiting
for the service.
The problem with this behaviour is that if for some reason the
EntityManager service is not coming up then your blueprint will still
start and block during the
first call until a timeout. This is probably not how you want your
service to behave. You also had not indication in diag that something is
wrong.
So in Aries JPA 2.2.0 I changed the code to correctly register a service
reference for the EntityManager service in blueprint. So blueprint will
delay the startup until
the service is coming up. You will also be able to see that the service
is missing using diag.
So the behavior with the new version is like if you try to provide and
use the same service in the same blueprint file. It will never start up.
So you will have to separate the
persistence unit from the code using the EntityManager to make it work.
Of course it would be great to be able to colocate and have a good
startup behaviour at the same time but I have not found a way to do so.
One option might be to register the service ref as optional but then you
would have problems again if the EM does not come up.
If someone finds a good way then I am open to any suggestions about this.
Christian
Am 14.11.2015 um 14:14 schrieb conejo:
I have an example in this direction:
https://github.com/LuisLozano/karafExamples
When using version 2.2.0 org.apache.aries.jpa.blueprint service is not
displayed. However, using version 2.1.0 the service itself perfectly
displayed.
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