Updating entities with Aries JPA in Declarative Services

[Jens Offenbach]

Hallo,
I have got a question regarding updates of JPA entities using Aries JPA with 
Declarative Services (DS). Hopefully, someone can help me.

Let's assume we have the Task entity from the example here: 
https://github.com/apache/aries/blob/trunk/jpa/examples/tasklist-model/src/main/java/org/apache/aries/jpa/example/tasklist/model/Task.java

When e.g. the fields "title" and "description" must be updated, is it mandatory 
to do it via JpaTemplate within a transaction like this:

jpa.tx(em -> {
    task.setDescription("New description");
    task.setTitle("New title");
    em.flush();
 });

or can safely be done without any transaction like this:

task.setDescription("New description");
task.setTitle("New title");

I would say, it can be done directly without any transactions on 
application-level because transaction-type is "JTA" and not "RESOURCE_LOCAL".

persistence.xml:
<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence";
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
        xsi:schemaLocation="
                http://java.sun.com/xml/ns/persistence
                http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd";
        version="2.0">
        <persistence-unit name="treedb" transaction-type="JTA">

                
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
                <!-- Only used when transaction-type=JTA -->
                
<jta-data-source>osgi:service/javax.sql.DataSource/(osgi.jndi.service.name=jdbc/treedb)</jta-data-source>
                <!-- Only used when transaction-type=RESOURCE_LOCAL -->
                
<non-jta-data-source>osgi:service/javax.sql.DataSource/(osgi.jndi.service.name=jdbc/treedb)</non-jta-data-source>

                <class>...</class>
                <exclude-unlisted-classes>true</exclude-unlisted-classes>

                <properties>
                        <property name="eclipselink.target-database" 
value="org.eclipse.persistence.platform.database.H2Platform" />

                        <property name="eclipselink.weaving" value = "static"/>
                        <property name="eclipselink.weaving.internal" 
value="true"/>
                        <property name="eclipselink.weaving.lazy" value="true" 
/>
                        <property name="eclipselink.weaving.changetracking" 
value="true" />
                        <property name="eclipselink.weaving.fetchgroups" 
value="true" />
                        <property name="eclipselink.weaving.eager" 
value="false" />

                        <property name="eclipselink.ddl-generation" 
value="create-tables" />
                        <property name="eclipselink.ddl-generation.output-mode" 
value="database" />
                        <property name="eclipselink.logging.level" 
value="FINEST" />
                </properties>
        </persistence-unit>
</persistence>

Thank you very much.

Regards,
Jens