EJB Application bindings

EJB Application bindings

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Before an application that is installed on an appserver can start, all EJB references and resource references defined in the application must be bound to the actual artifacts (enterprise beans or resources) defined in the appserver.
When defining bindings, you specify JNDI names for the referenceable and referenced artifacts in an application. The jndiName values specified for artifacts must be qualified lookup names. An example referenceable artifact is an EJB defined in an application. An example referenced artifact is an EJB or a resource reference used by the application.
Binding definitions are stored in...

ibm-xxx-bnd.xml
ibm-xxx-bnd.xmi

V7.0 binding definitions support files with the suffix of XML for EJB 3.0 and Web 2.5 modules. Modules earlier than Java EE 5 continue to use binding definition files with the suffix of XMI as in previous versions of WAS. The xxx can be ejb-jar, web, application or application-client.
For transitioning users: For EJB 3.0 modules, you do not need to specify JNDI binding names for each of the home or business interfaces on the enterprise beans. If we do not explicitly assign bindings, the EJB container assigns default bindings. Further, binding definitions are stored in ibm-ejb-jar-bnd.xml. See EJB 3.0 application bindings overview.trns
This page provides the following information about bindings:

Times when bindings can be defined
Required bindings
Other bindings that might be needed

Times when bindings can be defined

You can define bindings at the following times:

During application development
An application developer can create binding definitions in ibm-xxx-bnd.xml files for EJB 3.0 and Web 2.5 modules and in ibm-xxx-bnd.xmi files for pre-Java EE 5 modules. The application developer can create the files using a tool such as an IBM Rational developer tool or, for EJB 3.0 or Web 2.5 modules, using an XML editor or text editor. The developer then gives an enterprise application (.ear file) complete with bindings to an application assembler or deployer. When assembling the application, the assembler does not modify the bindings. Similarly, when installing the application onto a server supported by WAS, the deployer does not modify or override the bindings or generate default bindings unless changes to the bindings are necessary for successful deployment of the application.
During application assembly
An application assembler can define bindings in annotations or deployment descriptors of an application. Java EE 5 modules contain annotations in the source code. To declare an annotation, an application assembler precedes a keyword with an @ character ("at" sign). Bindings for pre-Java EE 5 modules are specified in the WebSphere Bindings section of a deployment descriptor editor. Modifying the deployment descriptors might change the binding definitions in the ibm-xxx-bnd.xmi files created when developing an application. After defining the bindings, the assembler gives the application to a deployer. When installing the application onto a server supported by WAS, the deployer does not modify or override the bindings or generate default bindings unless changes to the bindings are necessary to deploy the application.
During application installation
An application deployer or server administrator can modify the bindings when installing the application onto a server supported by WAS using the admin console. New binding definitions can be specified on the installation wizard pages.
Also, a deployer or administrator can select to generate default bindings during application installation. Selecting Generate default bindings during application installation instructs the product to fill in incomplete bindings in the application with default values. Existing bindings are not changed.
Restriction: We cannot define or override bindings during application installation for application clients. You must define bindings for application client modules during assembly and store the bindings in the ibm-application-client-bnd.xmi file.
During configuration of an installed application
After an application is installed onto a server supported by WAS, an application deployer or server administrator can modify the bindings by changing values in admin console pages such as those accessed from the settings page for the enterprise application.

Required bindings

Before an application can be successfully deployed, bindings must be defined for references to the following artifacts:

EJB JNDI names

For each EJB 2.1 or earlier EJB, specify a JNDI name. The name is used to bind an entry in the global JNDI name space for the EJB home object. An example JNDI name for a Product EJB in a Store application might be store/ejb/Product. The binding definition is stored in the META-INF/ibm-ejb-jar-bnd.xmi file.
If a deployer chooses to generate default bindings when installing the application, the installation wizard assigns EJB JNDI names having the form prefix/EJB_name to incomplete bindings. The default prefix is ejb, but can be overridden. The EJB_name is as specified in the deployment descriptor <ejb-name> tag.
During and after application installation, EJB JNDI names can be specified on the Provide JNDI names for beans panel. After installation, click Applications > Application Types > WebSphere enterprise apps > application_name > EJB JNDI names in the admin console.
You do not need to specify JNDI binding names for each of the EJB 3.0 home or business interfaces on the enterprise beans because the EJB container assigns default bindings. See EJB 3.0 application bindings overview.

Data sources for entity beans

Entity beans such as container-managed persistence (CMP) beans store persistent data in data stores. With CMP beans, an EJB container manages the persistent state of the beans. You specify which data store a bean uses by binding an EJB module or an individual enterprise bean to a data source. Binding an EJB module to a data source causes all entity beans in that module to use the same data source for persistence.
An example JNDI name for a Store data source in a Store application might be store/jdbc/store. For modules earlier than Java EE 5, the binding definition is stored in IBM binding files such as ibm-ejb-jar-bnd.xmi. A deployer can also specify whether authentication is handled at the container or application level.
WAS V 7.0 supports CMP beans in EJB 2.x or 1.x modules. V7.0 does not support CMP beans in EJB 3.0 modules.
If a deployer chooses to generate default bindings when installing the application, the install wizard generates the following for incomplete bindings:

For EJB 2.x .jar files, connection factory bindings based on the JNDI name and authorization information specified
For EJB 1.1 .jar files, data source bindings based on the JNDI name, data source user name and password specified

The generated bindings provide default connection factory settings for each EJB 2.x .jar file and default data source settings for each EJB 1.1 .jar file in the application being installed. No bean-level connection factory bindings or data source bindings are generated unless they are specified in the custom strategy rule supplied during default binding generation.
During and after application installation, we can map data sources to 2.x entity beans on the 2.x CMP bean data sources panel and on the 2.x entity bean data sources panel. After installation, click Applications > Application Types > WebSphere enterprise apps > application_name in the admin console, then select 2.x CMP bean data sources or 2.x entity bean data sources. We can map data sources to 1.x entity beans on the Map data sources for all 1.x CMP beans panel and on the Provide default data source mapping for modules containing 1.x entity beans panel. After installation, access console pages similar to those for 2.x CMP beans, except click links for 1.x CMP beans.

Backend ID for EJB modules

If an EJB .jar file that defines CMP beans contains mappings for multiple backend databases, specify the appropriate backend ID that determines which persister classes are loaded at run time.
Specify the backend ID during application installation. We cannot select a backend ID after the application is installed onto a server.
To enable backend IDs for individual EJB modules:

During application installation, select Deploy enterprise beans on the Select installation options panel. Selecting Deploy enterprise beans enables you to access the Provide options to perform the EJB Deploy panel.
On the Provide options to perform the EJB Deploy panel, set the database type to "" (null).

During application installation, if we select Deploy enterprise beans on the Select installation options panel and specify a database type for the EJB deployment tool on the Provide options to perform the EJB Deploy panel, previously defined backend IDs for all of the EJB modules are overwritten by the chosen database type.
The default database type is DB2UDB_V81.
The EJB deployment tool does not run during installation of EJB 3.0 modules.
For information on backend databases, refer to EJB deployment tool. For information on EJB Deploy options, refer to The ejbdeploy.

EJB references

An EJB reference is a logical name used to locate the home interface of an enterprise bean. EJB references are specified during deployment. At run time, EJB references are bound to the physical location (global JNDI name) of the enterprise beans in the target operational environment. EJB references are made available in the java:comp/env/ejb Java naming subcontext.
WAS ND v7.0 assigns default JNDI values for or automatically resolves incomplete EJB 3.0 reference targets.
For each EJB 2.1 or earlier EJB reference, specify a JNDI name. An example JNDI name for a Supplier EJB reference in a Store application might be store/ejb/Supplier. The binding definition is stored in IBM binding files such as ibm-ejb-jar-bnd.xmi. When the referenced EJB is also deployed in the same appserver, we can specify a server-scoped JNDI name. But if the referenced EJB is deployed on a different appserver or if ejb-ref is defined in an application client module, then you should specify the global cell-scoped JNDI name.
If a deployer chooses to generate default bindings when installing the application, the install wizard binds EJB references as follows: If an <ejb-link> is found, it is honored. If the ejb-name of an EJB defined in the application matches the ejb-ref name, then that EJB is chosen. Otherwise, if a unique EJB is found with a matching home (or local home) interface as the referenced bean, the reference is resolved automatically.
During and after application installation, we can specify EJB reference JNDI names on the Map EJB references to beans panel. After installation, click...
Applications | Application Types | WebSphere enterprise apps | application_name | EJB references

Best practice: To enable EJB reference targets to resolve automatically if the references are from EJB 2.1 or earlier modules or from Web 2.3 or earlier modules, select Generate default bindings on the Preparing for application installation panel or select Allow EJB reference targets to resolve automatically on the Select installation options, Map EJB references to beans, or EJB references console panels
For more information, refer to EJB references.

Resource references

A resource reference is a logical name used to locate an external resource for an application. Resource references are specified during deployment. At run time, the references are bound to the physical location (global JNDI name) of the resource in the target operational environment. Resource references are made available as follows:

Resource reference type Subcontext declared in
Java DataBase Connectivity (JDBC) data source java:comp/env/jdbc
JMS connection factory java:comp/env/jms
Java Mail connection factory java:comp/env/mail
Uniform Resource Locator (URL) connection factory java:comp/env/url

For each resource reference, specify a JNDI name. If a deployer chooses to generate default bindings when installing the application, the install wizard generates resource reference bindings derived from the <res-ref-name> tag, assuming that the java:comp/env name is the same as the resource global JNDI name.
During application installation, we can specify resource reference JNDI names on the Map resource references to references panel. Specify JNDI names for the resources that represent the logical names defined in resource references. We can optionally specify login configuration name and authentication properties for the resource. After specifying authentication properties, click OK to save the values and return to the mapping step. Each resource reference defined in an application must be bound to a resource defined in the WAS configuration. After installation, click Applications > Application Types > WebSphere enterprise apps > application_name > Resource references in the admin console to access the Resource references panel.

Virtual host bindings for Web modules

You must bind each Web module to a specific virtual host. The binding informs a Web server plug-in that all requests that match the virtual host must be handled by the Web app. An example virtual host to be bound to a Store Web app might be store_host. The binding definition is stored in IBM binding files such as WEB-INF/ibm-web-bnd.xmi.
If a deployer chooses to generate default bindings when installing the application, the install wizard sets the virtual host to default_host for each .war file.
During and after application installation, we can map a virtual host to a Web module defined in the application. On the Map virtual hosts for Web modules panel, specify a virtual host. The port number specified in the virtual host definition is used in the URL used to access artifacts such as servlets and JSPs files in the Web module. For example, an external URL for a Web artifact such as a JSP file is http://host_name:virtual_host_port/context_root/jsp_path. After installation, click Applications > Application Types > WebSphere enterprise apps > application_name > Virtual hosts in the admin console.

Message-driven beans

For each message-driven bean, specify a queue or topic to which the bean will listen. A message-driven bean is invoked by a JMS listener when a message arrives on the input queue that the listener is monitoring. A deployer specifies a listener port or JNDI name of an activation spec as defined in a connector module (.rar file) under WebSphere Bindings on the Beans page of an assembly tool EJB deployment descriptor editor. An example JNDI name for a listener port to be used by a Store application might be StoreMdbListener. The binding definition is stored in IBM bindings files such as ibm-ejb-jar-bnd.xmi. If a deployer chooses to generate default bindings when installing the application, the install wizard assigns JNDI names to incomplete bindings.

For EJB 2.0 or later message-driven beans deployed as JCA 1.5-compliant resources, the install wizard assigns JNDI names corresponding to activationSpec instances in the form eis/MDB_ejb-name.
For EJB 2.0 or later message-driven beans deployed against listener ports, the listener ports are derived from the message-driven bean <ejb-name> tag with the string Port appended.

During application installation using the admin console, we can specify a listener port name or an activation spec JNDI name for every message-driven bean on the Bind listeners for message-driven beans panel. A listener port name must be provided when using the JMS providers: Version 5 default messaging, WebSphere MQ, or generic. An activation specification must be provided when the application's resources are configured using the default messaging provider or any generic J2C resource adapter that supports inbound messaging. If neither is specified, then a validation error is displayed after you click Finish on the Summary panel.
If the module containing the message-driven bean is deployed on a 5.x deployment target and a listener port is not specified, then a validation error is displayed after you click Next.
After application installation, we can specify JNDI names and configure message-driven beans on console pages under...

Resources > JMS > JMS providers

...or under...

Resources > Resource adapters
.
Restriction: We can only bind message driven-beans defined in an EJB 3.0 module to an activation specification.

Message destination references

A message destination reference is a logical name used to locate an enterprise bean in an EJB module that acts as a message destination. Message destination references exist only in J2EE 1.4 and later artifacts such as--

J2EE 1.4 application clients
EJB 2.1 projects
2.4 Web apps

If multiple message destination references are associated with a single message destination link, then a single JNDI name for an enterprise bean that maps to the message destination link, and in turn to all of the linked message destination references, is collected during deployment. At run time, the message destination references are bound to the administered message destinations in the target operational environment.
If a message destination reference and a message-driven bean are linked by the same message destination, both the reference and the bean should have the same destination JNDI name. When both have the same name, only the destination JNDI name for the message-driven bean is collected and applied to the corresponding message destination reference.
If a deployer chooses to generate default bindings when installing the application, the install wizard assigns JNDI names to incomplete message destination references as follows: If a message destination reference has a <message-destination-link>, then the JNDI name is set to ejs/message-destination-linkName. Otherwise, the JNDI name is set to eis/message-destination-refName.

Other bindings that might be needed

Depending on the references in and artifacts used by the application, we might need to define bindings for references and artifacts not listed in this topic.

Related concepts

EJB 3.0 application bindings overview

Related tasks

Set enterprise application files
Assembling applications
Install enterprise application files with the console
Deploy enterprise apps
Develop applications that use JNDI

Related

Enterprise application settings

Resource reference type	Subcontext declared in
Java DataBase Connectivity (JDBC) data source	java:comp/env/jdbc
JMS connection factory	java:comp/env/jms
Java Mail connection factory	java:comp/env/mail
Uniform Resource Locator (URL) connection factory	java:comp/env/url