A client application performs business logic and makes
use of the framework provided by an underlying client. Developing
the code for a client application depends on the objects and functions you
want to exploit, and the programming model that you want to use.
Before you begin
Install the software development resources needed to develop client
applications for use with WebSphere® Application Server. During code development, you do not need access to the WebSphere Application Server. However, to assemble
some types of client applications you need to install files for the client
that provides the framework for the client application. Instead of installing WebSphere Application Server you can
install the Application Client feature, which provides the same resources
and clients to aid development of client applications. For information about
installing the Application Client on a development machine, see Installing Application Client for WebSphere Application Server.
About this task
To use a client application to access a remote object on an application
server, develop your client application code as described in the following
steps and the related topics. These topics only describe the client-specific
considerations; they do not describe general client programming models, which
you should already be familiar with. Samples for different types of client
applications are provided with the Application Client.
Procedure
- Choose the type of client that you want to use as a framework for
your client application. Decision factors for choosing a client
include whether you want to run a client application on Java EE or J2SE; whether
you want ease of use with a small installation footprint or full-function
with medium-large footprint; and whether you need licence to copy or redistribute
the client. For more information about choosing the type of client, see Choosing a type of client.
- Develop the client application code. The following substeps
are a high-level general procedure. Information specific to a type of client
is given in the related tasks.
- Create an instance of the object that you want to access on
the remote server. You can use full Java™ Naming and Directory Interface (JNDI)
support to get a suitable reference to administered objects from the server's
JNDI namespace. Alternatively, you can get suitable references to objects
programmatically without using JNDI.
Using the javax.naming.InitialContext class, the client
application program uses the lookup operation to access
the Java Naming and Directory Interface
(JNDI) namespace. The InitialContext class provides the lookup method
to locate resources.
You can compare the use of JNDI and programmatic
techniques by looking at the samples provided for the Java EE client and Java
thin client in an Application Client installation (for example, in
C:\wac70\samples\src\):
- Java EE client use of JNDI for BasicCalculatorHome: TechnologySamplesJ2EEClient\BasicCalculator\com\ibm\websphere\samples\technologysamples\basiccalcclient\BasicCalculatorClientJ2EE.java
- Java thin client programmatic retrieval of BasicCalculatorHome: TechnologySamplesThinClient\BasicCalculator\com\ibm\websphere\samples\technologysamples\basiccalcthinclient\BasicCalculatorClientThin.java
- Create a connection to the server. If the server
runs with security enabled, you can configure secure connections.
- Work with the objects to perform your business requirements.
For example, send and receive JMS messages, update database entries,
handle error conditions, and close resources used.
- Compile or assemble the client application. This creates
the JAR or EAR file that you can deploy to make the client application available
for use.
To compile your client application, include the JAR files needed
in the CLASSPATH setting for the javac command; for example,
any extra JAR files for the client application's own classes, JAR files
for IBM® Thin clients used, and JAR files
for JDBC provider classes.
Note: IBM-provided clients are not packaged
with JDBC provider classes. For example, the WebSphere Application Server Version 7.0 Java Thin application client is not packaged with Apache Derby 10.2 classes.
If your client application needs to use a database class (such as through
the JNDI lookup of a datasource), you must obtain the class files from the
database provider and make them available when compiling and running the client
application.
What to do next
After you develop a client application, deploy it into the environment
you want it to run.