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Developer Materials

servlet-async: How to Write an Asynchronous Servlet

What is it?

This is a sample project showing the use of asynchronous servlets.

It shows how to detach the execution of a long-running task from the request processing thread, so the thread is free to serve other client requests. The long-running tasks are executed using a dedicated thread pool and create the client response asynchronously.

A long-running task in this context does not refer to a computation intensive task executed on the same machine but could for example be contacting a third-party service that has limited resources or only allows for a limited number of concurrent connections. Moving the calls to this service into a separate and smaller sized thread pool ensures that less threads will be busy interacting with the long-running service and that more requests can be served that do not depend on this service.

System requirements

The application this project produces is designed to be run on Red Hat JBoss Enterprise Application Platform 6.1 or later.

All you need to build this project is Java 6.0 (Java SDK 1.6) or later, Maven 3.0 or later.

Configure Maven

If you have not yet done so, you must Configure Maven before testing the quickstarts.

Start the JBoss EAP Server

  1. Open a command prompt and navigate to the root of the JBoss EAP directory.
  2. The following shows the command line to start the server:

     For Linux:   EAP_HOME/bin/standalone.sh
     For Windows: EAP_HOME\bin\standalone.bat
    

Build and Deploy the Quickstart

NOTE: The following build command assumes you have configured your Maven user settings. If you have not, you must include Maven setting arguments on the command line. See Build and Deploy the Quickstarts for complete instructions and additional options.

  1. Make sure you have started the JBoss EAP server as described above.
  2. Open a command prompt and navigate to the root directory of this quickstart.
  3. Type this command to build and deploy the archive:

     mvn clean install jboss-as:deploy
    
  4. This will deploy target/jboss-servlet-async.war to the running instance of the server.

Access the application

The application will be running at the following URL http://localhost:8080/jboss-servlet-async/.

Undeploy the Archive

  1. Make sure you have started the JBoss EAP server as described above.
  2. Open a command prompt and navigate to the root directory of this quickstart.
  3. When you are finished testing, type this command to undeploy the archive:

     mvn jboss-as:undeploy
    

Run the Quickstart in JBoss Developer Studio or Eclipse

You can also start the server and deploy the quickstarts from Eclipse using JBoss tools. For more information, see Use JBoss Developer Studio or Eclipse to Run the Quickstarts

Debug the Application

If you want to debug the source code or look at the Javadocs of any library in the project, run either of the following commands to pull them into your local repository. The IDE should then detect them.

    mvn dependency:sources
    mvn dependency:resolve -Dclassifier=javadoc

Recent Changelog

  • Apr 11, 2014(Sande Gilda):Bz1086883 Update Product Version metadata to include EAP 6.3
  • Mar 12, 2014(Sande Gilda):Bz1074530 replace JBOSS_HOME with EAP_HOME
  • Mar 2, 2014(Sande Gilda):Bz1025766 Replace JBoss with JBoss EAP
  • Feb 14, 2014(Sande Gilda):Replace JDBS instructions with shared resource
  • Jan 28, 2014(Sande Gilda):JDF 602 Part 2 of changes to move common instructions to a shared repository. This commit contains the Maven Configuration link changes
  • Dec 16, 2013(Sande Gilda):JDF 577 Replace command line with command prompt when referring to a terminal
  • Nov 8, 2013(Sande Gilda):Bz1028448 Add spaces to end of metadata so it renders with a line break in HTML
  • Oct 8, 2013(Sande Gilda):BZ1011833 Add HTML versions of README files and fix deployment instructions
  • Oct 2, 2013(Sande Gilda):README add Product Versions metadata remove versions in text remove temp repo from settings.xml
  • Sep 24, 2013(Sande Gilda):Remove references to web profile
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