Implementing EJBs

To use an asynchronous EJB method, we need to create a session bean and configure it to have asynchronous methods. In the following code, we have an example of the implementation of a session bean called PdfHandler, which is responsible for saving PDF files on a filesystem:

import javax.ejb.AsyncResult;
import javax.ejb.Asynchronous;
import javax.ejb.Stateless;
import java.io.IOException;
import java.util.Date;
import java.util.concurrent.Future;

@Stateless
public class PdfHandler {

@Asynchronous
public Future<String> handler (FileBean file) throws IOException {

return new AsyncResult(
                FileSystemUtils.save(
                        file.getFile(),
"pdf",
"pdf_"+ new Date().getTime() + ".pdf" ));

}
}

In the preceding code block, we have the PdfHandler class, which contains a handler(FileBean file) method. This method is annotated with @Asynchronous to configure it as an asynchronous method. 

The following code demonstrates the configuration of the handle...