= servlet-async: How to Write an Asynchronous Servlet
:author: Christian Sadilek
:productName: WildFly
:productNameFull: WildFly Application Server
:jbossHomeName: WILDFLY_HOME
:productVersion: 12
:buildRequirements: Java 8.0 (Java SDK 1.8) or later and Maven 3.3.1 or later
include::../shared-doc/attributes.adoc[]

:level: Intermediate
:technologies: Asynchronous Servlet, CDI, EJB
:source: {githubRepoUrl}

[abstract]
The `servlet-async` quickstart demonstrates how to use asynchronous servlets to detach long-running tasks and free up the request processing thread.

:standalone-server-type: default
:archiveType: war

== What is it?

The `servlet-async` quickstart is a sample project showing the use of asynchronous servlets in {productNameFull}.

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.

//*************************************************
// Add System Requirements
//*************************************************
// == System Requirements
include::../shared-doc/system-requirements.adoc[leveloffset=+1]

//*************************************************
// Add Use of JBoss Home Name
//*************************************************
// == Use of {jbossHomeName}
include::../shared-doc/use-of-jboss-home-name.adoc[leveloffset=+1]

//*************************************************
// Start the server with the default profile
//*************************************************
// == Start the {productName} Standalone Server
include::../shared-doc/start-the-standalone-server.adoc[leveloffset=+1]

//*************************************************
// Build and deploy the quickstart WAR
//*************************************************
// == Build and Deploy the Quickstart
include::../shared-doc/build-and-deploy-the-quickstart.adoc[leveloffset=+1]


== Access the Application

The application will be running at the following URL http://localhost:8080/{artifactId}/.

//*************************************************
// Undeploy the quickstart archive
//*************************************************
// == Undeploy the Quickstart
include::../shared-doc/undeploy-the-quickstart.adoc[leveloffset=+1]


//*************************************************
// Add JBoss Developer Studio instructions
//*************************************************
// == Run the Quickstart in Red Hat JBoss Developer Studio or Eclipse
include::../shared-doc/run-the-quickstart-in-jboss-developer-studio.adoc[leveloffset=+1]

//*************************************************
// Deploy the quickstart to OpenShift
//*************************************************
// == Deploy the Quickstart to OpenShift Online
include::../shared-doc/deploy-to-openshift-online.adoc[leveloffset=+1]

//*************************************************
// Add info to debug the application
//*************************************************
// == Debug the Application
include::../shared-doc/debug-the-application.adoc[leveloffset=+1]
