We have a REST API to our narayana transaction manager, it is called REST-AT/RTS. To use it with a JTA resources (such as a database or JMS queue) you also need to use the RTS JTA bridge. Take a look at the jta-service quickstart to see how you can use it to solve your use case.

So you have configured Spring to use the narayana transaction manager (see the spring JTA quickstart). If so I think you can still use the RTS JTA bridging feature. If you follow the instructions for the quickstart you will see that you need to enable the optional RTS subsystem (the parent quickstart contains the instructions). Look at your wildfly distribution, there will be a example config file called ${JBOSS_HOME}/docs/examples/configs/standalone-rts.xml which automatically installs bridging support. This subsystem installs the REST-AT coordinator (the component that manages transactions propagated between JAX-RS services), the REST-AT JTA bridge (the component that enlists JTA resources with the REST-AT coordinator), and the JAX-RS filter responsible for receiving the transaction context on JAX-RS invocations. When the client commits the REST-AT transaction any JTA resources (such as JPA or JMS) that have been updated during any transactional JAX-RS resource invocation (ie resources annotated with the standard @TransactionAttribute annotation) will be told to prepare and commit. As is usual with "distributed XA transactions" if any resource cannot prepare then the whole transaction will abort.

I think if all of the services are deployed on the wildfly, it could be fine to use the RTS and the bridging. But if you run with the spring or spring-boot standalone application, it would be a problem with the transaction propagated.

If the two services need to coordinate their work on the database then you need to ensure that they are XA by setting the jta attribute on the datasource to true:

<datasource jta="true" jndi-name=oracle ...etc

Even though both services are running in the same JVM and doing work on the same datasource I am not aware of any optimisation that enables the work done as if it were a local transaction. Note that if you ever did decide to separate out the two services into separate JVMs then you would definitely need to set jta="true" on the datasources.

Have you marked the JAX_RS resource method with the @TransactionAttribute annotation. Did you manage to run the jta-service quickstart quickstart? Once you have seen that working you could then try migrating your own app to use the same techniques that it uses.

Are you running with the wildfly configuration that installs the org.wildfly.extension.rts module (the appropriate config file is docs/examples/configs/standalone-rts.xml).

Did you manage to successfully run the jta-service quickstart quickstart?

Did you make any progress. The example quickstart ( jta-service quickstart) runs regularly in our CI so if you are still having trouble I would go back to getting that example working and then see what you are doing differently.