Configure data access for application clients

 

Overview

Configuring data access for application clients involves specifying the resource reference and associated database information required for data access. This specification is done as part of the assembly and deployment steps for the application client.

There are two essential tools needed to configure data sources used by J2EE Application Clients: the Assembly Toolkit for defining the resource reference in the deployment descriptor, and the Application Client Resource Configuration Tool (ACRCT) for defining the connection to the database in the client deployment environment.

Data access from an application client uses the JDBC drive connection functions directly from the client side. It does not take advantage of the additional pooling support available in the WebSphere Application Server run time. Configuring data access for an application client does not require configuration of a JDBC provider and data source on the WebSphere Application Server server machine.

If you want to take advantage of the pooling and additional database functions provided by WebSphere Application Server, it is recommended that your client application utilize an enterprise bean running on the server side to perform data access.

Defining an application client resource reference in the Assembly Toolkit

  1. Assemble your application client module as described in "Assembling application clients."

  2. Create a new resource reference:

    1. In a J2EE Hierarchy view, right-click your application client module and click Open With > Deployment Descriptor Editor.

    2. On the References tab, click Add > Resource Reference > Next.

    3. On the Add Resource Reference page, enter the Name of this resource reference. The WebSphere Application client run time uses this name for two purposes: to bind the object into the java:comp/env portion of the JNDI namespace, and to find client specific configuration information. If the code for the application client performs a lookup for java:comp/env/jdbc/myDB, the name of the resource reference should be jdbc/myDB.

    4. For Type, select javax.sql.DataSource for JDBC connections.

    5. For Authentication, select Application if your client application intends to provide authentication information. If the WebSphere Application Client run time provides the authentication information (as configured by the Application Client Resource Configuration tool), select Container.

    6. Ignore the Sharing scope setting; it is unused in an application client resource reference. All WebSphere Application Client resources are currently unsharable.

    7. Close the deployment descriptor and save your changes.
    The JNDI name field appears under WebSphere Bindings after your add the reference.

 

Client configuration with the ACRCT

 

Overview

There are two client resources for you to configure in the Application Client Resource Configuration Tool (ACRCT) to enable data access from an application client: a data source provider and a data source.

Notes: The following WebSphere objects, which can be bound into the server namespace, are not supported on the client:

The WebSphere Application Server Client does not provide client database drivers. If your client application uses a database directly, rather than using an enterprise bean, provide the database drivers on the client machine. This action can involve contacting your database vendor to acquire client database driver code and licenses.

Instead of accessing the database directly, it is recommended that your client application use an enterprise bean. Accessing a database through an enterprise bean eliminates the need to have database drivers on the client machine because the database access is handled by the enterprise bean running on the WebSphere Application Server. Enterprise beans can also take advantage of the additional database functions provided by the WebSphere Application Server run time.

  1. Configure a new data source provider as described in Configuring new data source providers. This provider describes the JDBC database implementation for your client application.

  2. Enter the following information on the General Tab:

    1. A name for this data source provider.

    2. A description (this is optional).

    3. The classpath to the data source provider implementation classes or JAR files. This is optional if the implementation classes or JAR files are already in the classpath configuration of the client.

    4. The name of the implementation class. For example, for DB2 this value is COM.ibm.db2.jdbc.DB2DataSource. Remember this class must implement the javax.sql.DataSource class. The ACRCT does not verify this class and you receive an error when you run your client application if the class does not implement javax.sql.DataSource.
    Use the Custom Tab to configure non-standard properties of the data source provider. This panel enables you to enter property-value pairs. During run time the implementation classname is created and any custom properties added on this panel are set on the newly created data source object using reflection. Any properties configured on this panel must have an appropriate set method on the data source class. For example, assume there is a property called use2Phase and its value should be 1. On the custom panel you enter the value use2Phase into the name column and the value 1 into the value column. The WebSphere Application Client run time then uses reflection to find a property on the data source class called, typically setUse2Phase and call that method passing the value of 1. See your database product documentation for valid properties on your data source implementation.

  3. Click OK.

  4. Configure a new data source as described in Configuring new data sources for application clients.This describes the client properties of the database your client application uses.

  5. Enter the following information on the General Tab:

    1. A Name. This field is required and identifies a name for the Application Client Resource Configuration Tool to use. This name is not used by your client application program.

    2. A description (this field is optional).

    3. The JNDI name. This field is required and must match the value entered in the Name field on the Add Resource Reference page of the Assembly Toolkit. In the example above, set this value to jdbc/myDB.

    4. The Database Name (this field is optional).

    5. Your userid in the User field. This field is optional.

    6. Your password in the Password field. This password does not display. This field is optional.

    7. Your password again to confirm in the Re-Enter password field. Note: The User and Password fields are only used when the Authentication field on the Add Resource Reference page of the Assembly Toolkit is set to Container.
Related concepts
Data sources
J2EE application client class loading
Related tasks
Assembling application clients
Deploying application clients on workstation platforms