Learn about the Java Web
Start technology that is provided by the Java Standard
Edition runtime environment to deploy Java Enterprise
Edition application clients, including Thin application clients, on
the remote client machine with a single click from Web browser on
the client machine.
Before you begin
The supported client platforms for deploying application
clients using the Java Web Start are the same as the IBM® Application
Client for WebSphere® Application Server supported
platforms, except Linux® on Power and OS/400® operating
systems.
Before you begin this task, see the following topics
to understand Java Web Start technology and its
components:
Supported configurations: The Sun Java Web
Start, which is available from Sun Microsystems, is not compatible
with the IBM Runtime Environment, Java 2 Technology Edition, which
is provided by WebSphere Application
Server and the IBM Application
Client. The IBM Runtime Environment
contains some additional functionality that is not supported in the
Sun Java Web Start. Also, the IBM Runtime Environment uses a different
packaging structure than the Sun Java Web
Start. Use the IBM Runtime Environment.
sptcfg
About this task
To deploy application clients using Java Web
Start, the client machine must have at least a Java SE
runtime environment installed. The Java SE
runtime environment includes the Java Web
Start, which implements the JSR 56: Java Network
Launching Protocol and API. The application clients Enterprise Archive
(EAR) file is a Java archive (JAR) resource in a
JNLP descriptor file that resides on a central server. The JNLP descriptor
file also specifies the runtime environment requirement for running
the application.
WebSphere Application Server
provides a launcher class to launch the Java EE
application client in the application client container inside of Java Web Start. The client machine might not
have the IBM Application Client for WebSphere Application
Server installed. If this is the case, create and install an application
client container and runtime package as a runtime environment through Java Web Start. The JNLP descriptor file specifies
this runtime environment as the required runtime environment for running
the Java EE application client.
WebSphere Application
Server also provides command-line utility programs to create this
application client container and runtime package from an existing IBM Application
Client for WebSphere Application Server installation,
as well as an installer class to install this package as a runtime
environment for the application client container and also the Java Runtime Environment (JRE) in the IBM Application
Client for WebSphere Application Server installation.
To run the Java EE application client, the
EAR file is deployed as a JAR resource that is described in the JNLP
descriptor file.
Procedure
- Identify the client machine operating system, and install
the corresponding IBM Application Client for WebSphere Application Server on a development
machine. For example, if the Java EE
application clients are targeted to run on Windows® operating
systems, install the IBM Application Client for WebSphere Application Server for Windows. Follow the instructions for Installing Application Client for WebSphere Application Server.
- Run the utility programs to create the application client
container and runtime package.
- Use the buildClientRuntime tool utility
to create the package.
- Use the buildClientLibJars tool utility
to create the JAR files containing the launcher and the installer
class. This utility also zips up the properties files in the <app_client_root>/properties
directory.
- Create the runtime installer JNLP descriptor file.
The JNLP response must be included in the JNLP version ID to
indicate the current runtime version in the response header, for example, x-java-jnlp-version-id=1.6.0.
Using a servlet of a JavaServer Pages (JSP) file to provide a dynamic
JNLP response.
- Create the Java EE
application client launch JNLP descriptor file.
- Package the application client container runtime environments
and the Java EE application in an Enterprise
Archive (EAR) file. Depending on your preferred deployment
strategy, the files can be in two separate Web modules, or combined
into one.
- All JAR resources must be Java signed,
including the Java EE application client EAR file.
- Deploy the Enterprise Archive file on an application server,
and start the application. The Java EE
application client is ready to be deployed.
Example
A Java Web Start deployment Sample
is included in the client samples. This Sample demonstrates the steps
to deploy a Java EE application client with
an automated ANT script. The Sample has a servlet to generate the
runtime installer JNLP response with JNLP version ID, for example, x-java-jnlp-version-id.
Important: When the application client initially launches using Java Web Start from Sun Microsystems Java SE Runtime Environment 6.0, it installs
the Application Client runtime, which includes the IBM JRE.
An null pointer exception (NPE) is thrown from the
com.sun.deploy.services.WPlatformService.getSecureRandom() method.
This is a known bug in Sun Java SE
6 (
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6505528).
If you experience this exception, relaunch the application. The NPE
only occurs on the first launch of the application client.