XA数据源不创建事务

Question

I have an XA Datasource setup in Wildfly 8.2. It all works fine but when I call:

sql.query("LOCK TABLE table_name IN EXCLUSIVE MODE").execute();

I get an exception showing that Wildfly has not created a transaction:

org.postgresql.util.PSQLException: ERROR: LOCK TABLE can only be used in transaction blocks

If I manually create the transaction with a BEGIN and a COMMIT around my lock query, everything works as expected - but I would like Wildfly to do that for me automatically.

Why doesn't Wildfly create a transaction automatically and what do I need to do to fix it?

---

For reference, the code is called in a method like:

@RequestScoped
@Path("abc")
public class Controller {

@PUT
public Response m(Object data) {
  //HERE
}

Answer 1

If you want wildfly to create a transaction for you, use a ejb bean.. For your example, injecting a @Stateless session bean should work (since you are using RequestScoped, and stateless session beans have a similar lifecycle)

By default, each method of the stateless ejb will create a transaction for you, or if the client already has a current transaction, it will use it.

Code example:

@RequestScoped
@Path("abc")
public class Controller {

    @EJB
    private YourStatelessEJB statelessBean;

    @PUT
    public Response m(Object data) {
      //HERE
      statelessBean.doSomething(data)
}

@Stateless
@LocalBean
public class YourStatelessEJB {

    @PersistenceContext
    private EntityManager em;

    public YourStatelessEJB() {

    }

    public void doSomething(Object data) {
        // here you already have a transaction, created by the ejbcontainer
        ...
    }

}