Spring Data Neo4j transactions mixed with Hibernate transactions

[leonardo.moreno]

Hi

I have a project with a bunch of relational tables mapped with hibernate, using spring managed transactions and everything was working fine until I added Spring Data Neo4j. After that, I could interact with my Neo4j graph db but cannot write to my relational db. No exception, no warning, nothing. Just the request hangs in the call to a method marked with @Transactional.

I supose that I need to handle differently the transactions, but can't find how to do that.

Is there a wat yo make SDN transactions work together with Hibernate transactions?

Thanks in advance

[MichaelHunger]

Could you try to use @Neo4jTransactional or @Transactional("neo4jTransactionManager")

Neo4j defines a transaction manager and only aliases it as transactionManager but your hibernate tx-manager bean definition named "transactionManager" should have precedence.

[leonardo.moreno]

That's exactly the problem, the hibernate transactionManager doesn't take precedence.

My workaround was to copy the class Neo4jConfiguration, remove the transactionManager alias and use @Neo4jTransactional. With this I can use both transactions managers, but I really don't want to have my own version of that class. What can I do to avoid that conflict?

[bytor99999]

I thought the Neo4J transaction manager was a JTA transactionManager. Or maybe you can define a JTA Transaction Manager and wrap the two transaction managers in the JTA one, and then name the JTA one "transactionManager" I had to do something along these lines to have both Spring Data Neo4J and Spring Batch (which has relational tables) in my project.

Mark

[bytor99999]

Yeah, I had put this in my config

<bean id="neo4jTransactionManager"
    	   class="org.springframework.transaction.jta.JtaTransactionManager">
        <property name="transactionManager">
            <bean class="org.neo4j.kernel.impl.transaction.SpringTransactionManager">
                <constructor-arg ref="graphDatabaseService"/>
            </bean>
        </property>
        <property name="userTransaction">
            <bean class="org.neo4j.kernel.impl.transaction.UserTransactionImpl">
                <constructor-arg ref="graphDatabaseService"/>
            </bean>
        </property>
        <property name="allowCustomIsolationLevels" value="true"/>
    </bean>

And I have

<beans:bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <beans:property name="dataSource" ref="dataSource"/>
    </beans:bean>

for Jdbc to the Batch tables, in order to get both Neo4J and Batch to work together.

Hope that helps

Mark

[leonardo.moreno]

Hi Mark, thanks for your time.

How did you configure neo4j? with <neo4j:config ...>? Because the problem I have is that the Neo4JConfiguration class declares the transaction manager with 2 aliases neo4jTransactionManager and transactionManager and because hibernate looks for the bean named transactionManager, it hangs when trying to the obtain a transaction.

If that is going to generate a conflict the developers must be aware of that, don't you think?

Leonardo

[bytor99999]

Hi Mark, thanks for your time.

How did you configure neo4j? with <neo4j:config ...>? Because the problem I have is that the Neo4JConfiguration class declares the transaction manager with 2 aliases neo4jTransactionManager and transactionManager and because hibernate looks for the bean named transactionManager, it hangs when trying to the obtain a transaction.

If that is going to generate a conflict the developers must be aware of that, don't you think?

Leonardo

Yeah, I made a bean for my GraphDatabaseService. So I have

<bean id="graphDatabaseService" class="org.neo4j.kernel.EmbeddedGraphDatabase"
            destroy-method="shutdown">
        <constructor-arg index="0" value="${neo4j.location}"/>
        <constructor-arg index="1">
            <map>
                <entry key="allow_store_upgrade" value="${neo4j.upgrade}"/>
            </map>
        </constructor-arg>
    </bean>

    <neo4j:config graphDatabaseService="graphDatabaseService"/>

    <neo4j:repositories base-package="com.perfectworldprogramming.eventgate"/>

[MichaelHunger]

The problem is convenience. If people only use neo4j they want to use @Transactional which by default looks for "transactionManager", that's why the alias is there. I'm not sure how to provide both at the same time, having transactionManager when it is running standalone (aka the alias) and only neo4jTransactionManager when there are two.

Have you tried to declare your hibernate-tm with primary="true" ? And then use @Neo4jTransactional (if you want to keep them separate).

If you want the relational db and neo4j participate in the same tx, then it is required to either set up an 2PC TM like atomikos, jotm, the spring tx-manager or one of the appserver-providers. Or you go with the simpler model and configure the ChainedTransactionManager, see the example in CrossStoreNeo4jConfiguration.

HTH

Michael

[msduk]

I found this to be quite problematic also. It took me some time to figure out what was going wrong.

In the end I settled on this solution for the ChainedTransactionManager

<bean id="jpaTransactionManager"
	        class="org.springframework.orm.jpa.JpaTransactionManager">
	    <property name="entityManagerFactory" ref="localContainerEntityManagerFactoryBean"/>
	</bean>
	<bean id="xaTransactionManager"
	        class="org.springframework.data.neo4j.transaction.ChainedTransactionManager">
	    <constructor-arg>
	        <list>
	            <ref bean="jpaTransactionManager"/>
	            <ref bean="transactionManager"/>
	            <!--  There is an alias so neo4jTransactionManager and 
	            transactionManager refer to the same bean in neo4j:config
	            <ref bean="transactionManager"/>-->
	        </list>
	    </constructor-arg>
	</bean>

<tx:annotation-driven transaction-manager="xaTransactionManager" />

Then I used this (and a few others depending on the calling thread) custom annotation.

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Transactional(propagation=Propagation.REQUIRED, readOnly=false, value="xaTransactionManager")
public @interface TxInit {

}

Mark

[bytor99999]

Just out of curiosity. Has anyone just tried to declare a "transactionManager" and put it in the xml such that it would be read in after the Neo4J TransactionManager and therefore overwrite the entry of "transactionManager" to be yours?

Mark