Hi Alexander,

As has been discussed on the Aries lists before, I have no problem with someone 
creating a separate implementation of the Transaction Control service which 
leverages the OSGi JTA Service Specification. The reason that the current 
implementation doesn’t do this is twofold:

By embedding a transaction manager the current Tx Control implementation can 
avoid the javax.transaction split package from the JVM. This makes the 
implementation easier to use and deploy because the user doesn’t need to mess 
around with the boot class path, or worry about what JTA version is available
By embedding a transaction manager the current Tx control implementation can 
rely on specific behaviours of the transaction manager that it uses. This means 
that the Tx control implementation can support the last resource gambit and XA 
recovery.

If this is a proof of concept project then are you able to share it somewhere 
(e.g. GitHub)? I’d like to help you get to the bottom of the NPE that you’re 
seeing as I don’t think it should be possible for that to be happening!

Finally - yes the Aries user list is the best place to talk about this, but I 
don’t want to move the conversation myself as I don’t know whether you’re 
registered for that list, and don’t want you to miss my replies.

Regards,

Tim


> On 14 Sep 2017, at 07:53, <alexander.sah...@brodos.de> 
> <alexander.sah...@brodos.de> wrote:
> 
> Hi Tim.
> 
> I'm using the 2.6.1 version of aries jpa support already. Normal transaction 
> control with blueprint and @Transactional annotation was working fine.
> 
> To have better control over startup dependencies and cope with disappearing 
> and appearing services during runtime we invest some time in a 
> Proof-Of-Concept for switching over to declarative services (DS). Everything 
> works fine so far - even restful services for DS with cxf-dosgi works fine. 
> Last bit to get it working is transaction management. With DS, the 
> @Transactional annotation is not working anymore due to the lack of 
> interceptors with DS.
> 
> What do you think of the idea that tx-control should pick up a JTS 
> Transaction manager from the service registry instead of creating an own one 
> with new operator which is in fact tightly coupled. To implement loose 
> coupling here we should add a factory that may be configurable in the factory 
> config file.
> 
> BTW, should we switch the discussion to aries group still?
> 
> Best, Alexander.
> 
> 
> 
> Hi Alexander,
> 
> That looks like it should be fine - what version of Aries JPA are you using? 
> There were some fixes made to Aries JPA in 2.4.0 to add support for JPA 2.1 
> configuration properties which are needed by the transaction control 
> implementation, and I think that there were then more fixes in 2.5.0 which 
> are needed to get XA working with Hibernate. 2.6.1 is the latest release 
> version.
> 
> Regards,
> 
> Tim
> 
> 
>> On 13 Sep 2017, at 15:42, alexander.sah...@brodos.de 
>> <mailto:alexander.sah...@brodos.de> wrote:
>> 
>> Thanks Tim for the update.
>> 
>> I tried the approach with providing a factory config in 
>> karaf.dir/etc/org.apache.aries.tx.control.jpa.xa.cfg with config as:
>> osgi.unit.name=DSContext2
>> osgi.jdbc.driver.class=org.h2.Driver
>> url=jdbc:h2:mem:article
>> user=sa
>> password=
>> 
>> whilst having a mininmal persistence.xml like:
>> <persistence-unit name="DSContext" >
>>         <properties>
>>             <property name="hibernate.dialect" 
>> value="org.hibernate.dialect.H2Dialect" />
>>         </properties>
>>     </persistence-unit>
>> 
>> (without the dialect I see another exception; Access to 
>> DialectResolutionInfo cannot be null when 'hibernate.dialect' not set).
>> 
>> Now I get further in the process (transaction enlistment works) but when 
>> actually accessing the database, the entity manager throws a NPE while 
>> trying to open the connection. In 
>> JPAEntityManagerProviderFactoryImpl.EnlistingDataSource.enlistedConnection() 
>> while calling supplier.call, the supplier.delegate member is null:
>> 
>> org.osgi.service.transaction.control.TransactionException: There was a 
>> problem getting hold of a database connection
>>         at 
>> org.apache.aries.tx.control.jpa.xa.impl.JPAEntityManagerProviderFactoryImpl$EnlistingDataSource.enlistedConnection(JPAEntityManagerProviderFactoryImpl.java:241)
>>  ~[?:?]
>>         at 
>> org.apache.aries.tx.control.jpa.xa.impl.JPAEntityManagerProviderFactoryImpl$EnlistingDataSource.getConnection(JPAEntityManagerProviderFactoryImpl.java:193)
>>  ~[?:?]
>>         at 
>> org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:122)
>>  ~[?:?]
>>         at 
>> org.hibernate.internal.NonContextualJdbcConnectionAccess.obtainConnection(NonContextualJdbcConnectionAccess.java:35)
>>  ~[?:?]
>>         at 
>> org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.acquireConnectionIfNeeded(LogicalConnectionManagedImpl.java:99)
>>  ~[?:?]
>>         at 
>> org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.getPhysicalConnection(LogicalConnectionManagedImpl.java:129)
>>  ~[?:?]
>>         at 
>> org.hibernate.engine.jdbc.internal.StatementPreparerImpl.connection(StatementPreparerImpl.java:47)
>>  ~[?:?]
>>         at 
>> org.hibernate.engine.jdbc.internal.StatementPreparerImpl$5.doPrepare(StatementPreparerImpl.java:146)
>>  ~[?:?]
>>         at 
>> org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:172)
>>  ~[?:?]
>>         at 
>> org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:148)
>>  ~[?:?]
>>         at 
>> org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1940) ~[?:?]
>>         at 
>> org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1909) ~[?:?]
>>         at 
>> org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1887) ~[?:?]
>>         at org.hibernate.loader.Loader.doQuery(Loader.java:932) ~[?:?]
>>         at 
>> org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:349)
>>  ~[?:?]
>>         at org.hibernate.loader.Loader.doList(Loader.java:2615) ~[?:?]
>>         at org.hibernate.loader.Loader.doList(Loader.java:2598) ~[?:?]
>>         at 
>> org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2430) ~[?:?]
>>         at org.hibernate.loader.Loader.list(Loader.java:2425) ~[?:?]
>>         at 
>> org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:335) ~[?:?]
>>         at 
>> org.hibernate.internal.SessionImpl.listCustomQuery(SessionImpl.java:2153) 
>> ~[?:?]
>>         at 
>> org.hibernate.internal.AbstractSharedSessionContract.list(AbstractSharedSessionContract.java:991)
>>  ~[?:?]
>>         at 
>> org.hibernate.query.internal.NativeQueryImpl.doList(NativeQueryImpl.java:147)
>>  ~[?:?]
>>         at 
>> org.hibernate.query.internal.AbstractProducedQuery.list(AbstractProducedQuery.java:1410)
>>  ~[?:?]
>>         at 
>> org.hibernate.query.internal.AbstractProducedQuery.getSingleResult(AbstractProducedQuery.java:1459)
>>  ~[?:?]
>>         at 
>> com.brodos.ds.persistence.h2.TestRepositoryImpl.lambda$checkHealth$0(TestRepositoryImpl.java:47)
>>  ~[?:?]
>>         at 
>> org.apache.aries.tx.control.service.common.impl.AbstractTransactionControlImpl$TransactionBuilderImpl.doWork(AbstractTransactionControlImpl.java:161)
>>  [241:tx-control-service-xa:0.0.3]
>>         at 
>> org.apache.aries.tx.control.service.common.impl.AbstractTransactionControlImpl$TransactionBuilderImpl.required(AbstractTransactionControlImpl.java:84)
>>  [241:tx-control-service-xa:0.0.3]
>>         at 
>> org.apache.aries.tx.control.service.common.impl.AbstractTransactionControlImpl.required(AbstractTransactionControlImpl.java:263)
>>  [241:tx-control-service-xa:0.0.3]
>>         at 
>> com.brodos.ds.persistence.h2.TestRepositoryImpl.checkHealth(TestRepositoryImpl.java:44)
>>  [160:com.brodos.example.ds.DSContext-infrastructure:1.0.0.SNAPSHOT]
>>         at 
>> com.brodos.ds.service.impl.MainHealthCheck.checkHealth(MainHealthCheck.java:29)
>>  [209:com.brodos.example.ds.DSContext-service:1.0.0.SNAPSHOT]
>>         at 
>> com.brodos.ds.application.boundary.impl.HealthCheckImpl.checkHealth(HealthCheckImpl.java:37)
>>  [212:com.brodos.example.ds.DSContext-application:1.0.0.SNAPSHOT]
>>         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]
>>         at 
>> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
>>  ~[?:?]
>>         at 
>> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>>  ~[?:?]
>>         at java.lang.reflect.Method.invoke(Method.java:497) ~[?:?]
>>         at 
>> org.apache.cxf.service.invoker.AbstractInvoker.performInvocation(AbstractInvoker.java:180)
>>  [84:org.apache.cxf.cxf-core:3.1.12]
>>         at 
>> org.apache.cxf.service.invoker.AbstractInvoker.invoke(AbstractInvoker.java:96)
>>  [84:org.apache.cxf.cxf-core:3.1.12]
>>         at org.apache.cxf.jaxrs.JAXRSInvoker.invoke(JAXRSInvoker.java:189) 
>> [85:org.apache.cxf.cxf-rt-frontend-jaxrs:3.1.12]
>>         at org.apache.cxf.jaxrs.JAXRSInvoker.invoke(JAXRSInvoker.java:99) 
>> [85:org.apache.cxf.cxf-rt-frontend-jaxrs:3.1.12]
>>         at 
>> org.apache.cxf.interceptor.ServiceInvokerInterceptor$1.run(ServiceInvokerInterceptor.java:59)
>>  [84:org.apache.cxf.cxf-core:3.1.12]
>>         at 
>> org.apache.cxf.interceptor.ServiceInvokerInterceptor.handleMessage(ServiceInvokerInterceptor.java:96)
>>  [84:org.apache.cxf.cxf-core:3.1.12]
>>         at 
>> org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(PhaseInterceptorChain.java:308)
>>  [84:org.apache.cxf.cxf-core:3.1.12]
>>         at 
>> org.apache.cxf.transport.ChainInitiationObserver.onMessage(ChainInitiationObserver.java:121)
>>  [84:org.apache.cxf.cxf-core:3.1.12]
>>         at 
>> org.apache.cxf.transport.http.AbstractHTTPDestination.invoke(AbstractHTTPDestination.java:263)
>>  [92:org.apache.cxf.cxf-rt-transports-http:3.1.12]
>>         at 
>> org.apache.cxf.transport.servlet.ServletController.invokeDestination(ServletController.java:234)
>>  [92:org.apache.cxf.cxf-rt-transports-http:3.1.12]
>>         at 
>> org.apache.cxf.transport.servlet.ServletController.invoke(ServletController.java:208)
>>  [92:org.apache.cxf.cxf-rt-transports-http:3.1.12]
>>         at 
>> org.apache.cxf.transport.servlet.ServletController.invoke(ServletController.java:160)
>>  [92:org.apache.cxf.cxf-rt-transports-http:3.1.12]
>>         at 
>> org.apache.cxf.transport.servlet.CXFNonSpringServlet.invoke(CXFNonSpringServlet.java:189)
>>  [92:org.apache.cxf.cxf-rt-transports-http:3.1.12]
>>         at 
>> org.apache.cxf.transport.servlet.AbstractHTTPServlet.handleRequest(AbstractHTTPServlet.java:299)
>>  [92:org.apache.cxf.cxf-rt-transports-http:3.1.12]
>>         at 
>> org.apache.cxf.transport.servlet.AbstractHTTPServlet.doGet(AbstractHTTPServlet.java:223)
>>  [92:org.apache.cxf.cxf-rt-transports-http:3.1.12]
>>         at javax.servlet.http.HttpServlet.service(HttpServlet.java:687) 
>> [69:javax.servlet-api:3.1.0]
>>         at 
>> org.apache.cxf.transport.servlet.AbstractHTTPServlet.service(AbstractHTTPServlet.java:274)
>>  [92:org.apache.cxf.cxf-rt-transports-http:3.1.12]
>>         at 
>> org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:845) 
>> [128:org.eclipse.jetty.servlet:9.3.14.v20161028]
>>         at 
>> org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:584) 
>> [128:org.eclipse.jetty.servlet:9.3.14.v20161028]
>>         at 
>> org.ops4j.pax.web.service.jetty.internal.HttpServiceServletHandler.doHandle(HttpServiceServletHandler.java:71)
>>  [150:org.ops4j.pax.web.pax-web-jetty:6.0.6]
>>         at 
>> org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
>>  [127:org.eclipse.jetty.server:9.3.14.v20161028]
>>         at 
>> org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:548) 
>> [125:org.eclipse.jetty.security:9.3.14.v20161028]
>>         at 
>> org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:226)
>>  [127:org.eclipse.jetty.server:9.3.14.v20161028]
>>         at 
>> org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1180)
>>  [127:org.eclipse.jetty.server:9.3.14.v20161028]
>>         at 
>> org.ops4j.pax.web.service.jetty.internal.HttpServiceContext.doHandle(HttpServiceContext.java:284)
>>  [150:org.ops4j.pax.web.pax-web-jetty:6.0.6]
>>         at 
>> org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:512) 
>> [128:org.eclipse.jetty.servlet:9.3.14.v20161028]
>>         at 
>> org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185)
>>  [127:org.eclipse.jetty.server:9.3.14.v20161028]
>>         at 
>> org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1112)
>>  [127:org.eclipse.jetty.server:9.3.14.v20161028]
>>         at 
>> org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
>>  [127:org.eclipse.jetty.server:9.3.14.v20161028]
>>         at 
>> org.ops4j.pax.web.service.jetty.internal.JettyServerHandlerCollection.handle(JettyServerHandlerCollection.java:80)
>>  [150:org.ops4j.pax.web.pax-web-jetty:6.0.6]
>>         at 
>> org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:134)
>>  [127:org.eclipse.jetty.server:9.3.14.v20161028]
>>         at org.eclipse.jetty.server.Server.handle(Server.java:534) 
>> [127:org.eclipse.jetty.server:9.3.14.v20161028]
>>         at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:320) 
>> [127:org.eclipse.jetty.server:9.3.14.v20161028]
>>         at 
>> org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:251) 
>> [127:org.eclipse.jetty.server:9.3.14.v20161028]
>>         at 
>> org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:273)
>>  [119:org.eclipse.jetty.io <http://org.eclipse.jetty.io/>:9.3.14.v20161028]
>>         at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:95) 
>> [119:org.eclipse.jetty.io <http://org.eclipse.jetty.io/>:9.3.14.v20161028]
>>         at 
>> org.eclipse.jetty.io.SelectChannelEndPoint$2.run(SelectChannelEndPoint.java:93)
>>  [119:org.eclipse.jetty.io <http://org.eclipse.jetty.io/>:9.3.14.v20161028]
>>         at 
>> org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.executeProduceConsume(ExecuteProduceConsume.java:303)
>>  [130:org.eclipse.jetty.util:9.3.14.v20161028]
>>         at 
>> org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.produceConsume(ExecuteProduceConsume.java:148)
>>  [130:org.eclipse.jetty.util:9.3.14.v20161028]
>>         at 
>> org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.run(ExecuteProduceConsume.java:136)
>>  [130:org.eclipse.jetty.util:9.3.14.v20161028]
>>         at 
>> org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:671)
>>  [130:org.eclipse.jetty.util:9.3.14.v20161028]
>>         at 
>> org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:589)
>>  [130:org.eclipse.jetty.util:9.3.14.v20161028]
>>         at java.lang.Thread.run(Thread.java:745) [?:?]
>> Caused by: java.lang.NullPointerException
>>         at 
>> org.apache.aries.tx.control.jpa.xa.impl.JPAEntityManagerProviderFactoryImpl$EnlistingDataSource.lambda$getConnection$4(JPAEntityManagerProviderFactoryImpl.java:193)
>>  ~[?:?]
>>         at 
>> org.apache.aries.tx.control.jpa.xa.impl.JPAEntityManagerProviderFactoryImpl$EnlistingDataSource.enlistedConnection(JPAEntityManagerProviderFactoryImpl.java:230)
>>  ~[?:?]
>>         ... 78 more
>> 
>> Best, Alexander
>> 
>> 
>> 
>> Hi Alexander,
>> 
>> So what you’re doing is passing a fully configured EntityManagerFactory to 
>> the resource provider factory. If you create the provider this way then you 
>> are responsible for setting up all of the EntityManagerFactory’s 
>> configuration, including how it’s going to integrate with transaction 
>> control. For local transactions there is nothing to integrate with , but in 
>> the general case this is actually quite hard to do, and I would advise not 
>> trying to do it.
>> 
>> As you can see the EntityManagerFactory version of the provider factory 
>> <https://github.com/apache/aries/blob/ed8dbc79758766081203056cff27eb0bcbd7efb3/tx-control/tx-control-providers/jpa/tx-control-provider-jpa-xa/src/main/java/org/apache/aries/tx/control/jpa/xa/impl/JPAEntityManagerProviderFactoryImpl.java#L122>
>>  does quite a bit less setup on your behalf than the configuration-driven 
>> version does 
>> <https://github.com/apache/aries/blob/ed8dbc79758766081203056cff27eb0bcbd7efb3/tx-control/tx-control-providers/jpa/tx-control-provider-jpa-xa/src/main/java/org/apache/aries/tx/control/jpa/xa/impl/XAJPAEMFLocator.java#L72>.
>>  If you were to 
>> provide a factory configuration for the “org.apache.aries.tx.control.jpa.xa” 
>> pid containing “osgi.unit.name=<your persistence unit’s name>” and any 
>> necessary datasource configuration (i.e. that’s not coming from the 
>> persistence xml) then you could inject the JPAEntityManagerProvider directly 
>> as a service.
>> 
>> More documentation about configuration-driven resources for Aries Tx-Control 
>> is available at 
>> http://aries.apache.org/modules/tx-control/xaJPA.html#creating-a-resource-using-a-factory-configuration
>>  
>> <http://aries.apache.org/modules/tx-control/xaJPA.html#creating-a-resource-using-a-factory-configuration>
>> 
>> Another thing that probably could be done would be to look at dynamically 
>> installing the plugin when using the EntityManagerFactoryBuilder version of 
>> the factory method. This, however, would need a patch to Aries Transaction 
>> Control, and would still not make your existing code work.
>> 
>> Regards,
>> 
>> Tim
>> 
>> 
>>> On 13 Sep 2017, at 10:59, <alexander.sah...@brodos.de 
>>> <mailto:alexander.sah...@brodos.de>> <alexander.sah...@brodos.de 
>>> <mailto:alexander.sah...@brodos.de>> wrote:
>>> 
>>> Hi Tim,
>>> 
>>> I use a JPAEntityManagerProviderFactory (providerFactory) which I inject as 
>>> a service reference into my repository class.
>>> Furthermore, I inject a EntityManagerFactory (emf) into the repository 
>>> class as well as the TransactionControl (txControl).
>>> 
>>> The provider Factory is created by pax-jdbc (I use hibernate).
>>> 
>>> This provider factory is then used to get the Entity manager like this:
>>> 
>>> EntityManager em = providerFactory.getProviderFor(emf, 
>>> null).getResource(txControl);
>>> 
>>> It fails giving an exception telling that transaction cannot be joined, 
>>> because it's not open.
>>> 
>>> The wrapping call is like this:
>>> txControl.build()
>>>                 .required(
>>>                         () -> repo.store(article));
>>> 
>>> Best, Alexander.
>>> 
>>> 
>>> 
>>> Hi Alexander,
>>> 
>>> Do you have a code example of how you’re obtaining and using the 
>>> EntityManager? There should be no usage of the OSGiJtaPlatform from the 
>>> tx-control XA JPA resource provider, which means that there’s either a bug 
>>> in the resource provider, or something is misconfigured. If you are a 
>>> member of the Aries user mailing list then that would be a better place to 
>>> continue this discussion.
>>> 
>>> Regards,
>>> 
>>> Tim
>>> 
>>>> On 13 Sep 2017, at 09:21, Guillaume Nodet <gno...@apache.org 
>>>> <mailto:gno...@apache.org>> wrote:
>>>> 
>>>> Fwiw, you should ask on the Aries mailing list, where tx-control is 
>>>> developed.
>>>> 
>>>> I've recently worked on a new project called pax-transx which provides an 
>>>> abstraction layer on top of transaction managers so that some features can 
>>>> be accessed in a common way.  I think this should be used in tx-control 
>>>> instead of wrapping the tm again and not being flexible.
>>>> Right now, tx-control uses its own instance of transaction manager and 
>>>> there's no way around afaik, so you can't use the karaf transaction 
>>>> feature if you want to use it.
>>>> Anyway, I'd gladly support you if you go to the aries mailing list to 
>>>> raise this point !
>>>> 
>>>> 2017-09-13 9:52 GMT+02:00 <alexander.sah...@brodos.de 
>>>> <mailto:alexander.sah...@brodos.de>>:
>>>> Hello.
>>>> 
>>>> I'm trying to get tx-control with XA transactions running (local is 
>>>> working).
>>>> I found that tx-control opens a JTA transaction using 
>>>> RecoveryWorkAroundTransactionManager (derived from geronimo's 
>>>> TransactionManager Implementation) explicitly instead of using the 
>>>> registered TransactionManager (aries in my case for karaf 4.0.9). When 
>>>> hibernate EntityManager implementation tries to join the transaction it 
>>>> fails because it uses the TransactionManager provided by OsgiJtaPlatform 
>>>> (from hibernate-osgi) which is of course the one registered in osgi 
>>>> ecosystem.
>>>> 
>>>> I think that the tx-control implementation has to use the 
>>>> TransactionManager registered with OSGi.
>>>> 
>>>> Has anyone got that thing ever running?
>>>> 
>>>> Best Alexander.
>>>> 
>>>> 
>>>> 
>>>> -- 
>>>> ------------------------
>>>> Guillaume Nodet
>>>> 
>>> 
>> 
> 

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