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;@Statelesspublic 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, ...