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Geronimo uses the OpenEJB container for providing EJB services. With the advent of Java EE, the EJB container services such as transaction management, security, life cycle management can be declared in the EJB class itself using annotations. However, the EJB deployment descriptor can still be provided via usage of the ejb-jar.xml file.
The Geronimo-specific deployment plan for an EJB application, which is usually packaged as an EJB JAR file, is called "openejb-jar.xml". The openejb-jar.xml deployment plan is used to in conjunction with the ejb-jar.xml Java EE deployment plan to deploy enterprise applications to the Geronimo application server. The openejb-jar.xml deployment plan is an optional file, but is typically used when deploying a EJB JAR file. It is used to map roles and resource (e.g., security roles, EJB names, database resources, JMS resources, etc.) declared in the openejb-jar.xml deployment plan to corresponding entities deployed in the server. Also, if there are any EJB container specific configurations required those setting are configured in this deployment plan as well. If the EJB module depends on any third party libraries or other services running in the server, all these third party libraries and the services are specified in the openejb-jar.xml file. Some EJB applications require class loading requirements different from the default class loading behavior. The openejb-jar.xml file allows the application deployer to configure this as well. There are many more configurations that could be done through openejb-jar.xml
file depending on the requirements of the EJB application.
The openejb-jar.xml Geronimo-specific deployment plan can be packaged as follows:
The openejb-jar.xml deployment plan is defined by the openejb-jar-2.1.xsd schema located in the <geronimo_home>/schema/ subdirectory of the main Geronimo installation directory. The openejb-jar-2.1.xsd schema is shown here:
The root XML element in the openejb-jar-2.2.xsd schema is the <openejb-jar-2.2> element. The top-level XML elements of the <openejb-jar> root element are described in the sections below. The deployment plan should always use the OpenEJB namespace, and it typically requires elements from the Geronimo Naming, Geronimo Security, and Geronimo System namespaces. Additionally, it has a required attribute to identify its configuration name. A typical deployment for openejb-jar.xml can be presented as follows:
The <sys:environment> XML element uses the Geronimo System namespace, which is used to specify the common elements for common libraries and module-scoped services, which is documented here:
The <sys:environment> element contains the following elements:
An example openejb-jar.xml file is shown below using the <sys:environment> element:
The <sec:security> XML element uses the Geronimo Security namespace, and is documented here:
The <sec:security> element groups the security role mapping settings for the EJB application. This is an optional element, but if it is present all the EJB modules must make the appropriate access checks as outlined in the JACC specification. This element includes the <role-mapping> section that references the role(s) defined in the <security-role> element in the application.xml file.
The <sys:gbean> XML element uses the Geronimo System namespace described at http://geronimo.apache.org/schemas-3.0/docs/geronimo-module-1.2.xsd.html.
The <sys:gbean> element is used to define GBean(s) that are configured and deployed with the EJB. These additional Geronimo services will be deployed when the application is deployed (and stopped when the application is stopped). Normally, the implementation classes for these services are included at the server level and referenced using a dependency element.
Container Managed Persistence (CMP) is still fully supported in OpenEJB/Geronimo, although the Java Persistence API is generally considered a better approach in Java EE. Apache Geronimo uses OpenJPA for providing Java Persistence API to Java EE applications deployed in the server. More information and details about the JPA deployment descriptor can be found here: Creating deployment plans for Java Persistence API.
The <naming:cmp-connection-factory> XML element uses the Geronimo Naming namespace, which is used to identify the common elements for resolving EJB references, resource references, and Web services references, which is documented here:
The <naming:cmp-connection-factory> element is used to specify a JDBC connection pool that should be used by Container Managed Persistence (CMP) entity beans to connect to a database. Since the <naming:cmp-connection-factory> element points to a database pool using the same syntax a resource reference uses, there are multiple methods available to refer to the connection pool. It can be specified by a simple name using the <resource-link> element, by pattern using the <pattern> element, or finally by URL using the <url> element. The resource-link handles most common resource situations where the JDBC pools are deployed as J2EE connectors in the same application, or deployed standalone in the same server. But pattern or URL can be use for any. An example openejb-jar.xml using all three techniques is shown:
The <ejb-ql-compiler-factory> XML element uses the OpenEJB default namespace for a openejb-jar.xml file, which is documented here:
The <ejb-ql-compiler-factory> element is used to specify the name of a Java class that can compile EJB-QL (Query Language) queries into SQL statements for a particular database product. This must be the fully-qualified class name of a class that implements org.tranql.sql.EJBQLCompilerFactory. The default is for the Derby database, which ships with Geronimo, although it may work for other database products as well. An example openejb-jar.xml using the <ejb-ql-compiler-factory> XML element is shown:
The <db-syntax-factory> XML element uses the OpenEJB default namespace for a openejb-jar.xml file, which is documented here:
The <db-syntax-factory> element is used to specify the name of a Java class that can customize CMP SQL statements for a particular database product. This must be the fully-qualified class name of a class that implements org.tranql.sql.DBSyntaxFactory. The default is for the Derby database, which ships with Geronimo, although it may work for other database products as well. An example openejb-jar.xml using the <db-syntax-factory> XML element is shown:
The <enforce-foreign-key-constraints> XML element uses the OpenEJB default namespace for a openejb-jar.xml file, which is documented here:
The <enforce-foreign-key-constraints> element is effectively a true/false element – if it's present that means true, and if it's not present, that means false. If true, then Geronimo will make a special effort to execute insert, update, and delete statements in an order consistent with the foreign keys between tables. If false, then Geronimo will execute statements in any order, though still within the same transaction. This element should be present if the underlying database enforces foreign keys at the moment a statement is executed instead of at the end of the transaction. An example openejb-jar.xml setting the <db-syntax-factory> XML element to "true" is shown:
The <relationships> XML element uses the OpenEJB default namespace for a openejb-jar.xml file, which is described here:
Container-managed relationships are initially defined in the ejb-jar.xml deployment descriptor, but the mappings to specific database elements are defined in the openejb-jar.xml file using the <relationship> element.
Unless otherwise noted, all the Common, EJB Entity, EJB Session, and EJB Message-driven elements use the OpenEJB default namespace for a openejb-jar.xml file, which is documented here:
The <enterprise-beans> element used to specify references by <entity>, <session>, or <message-driven> EJB's. For example, a EJB Entity Bean would be specified similarly as below in an openejb-jar.xml file:
A EJB Session Bean would be specified similarly as below in an openejb-jar.xml file:
And an EJB Message-driven Bean would be specified similarly as below in an openejb-jar.xml file:
The <ejb-name> element identifies the EJB that these settings apply to and must match the <ejb-name> for the EJB in ejb-jar.xml file.
The Home interface for the EJB is registered in JNDI at the address specified here. This global JNDI name is used by application clients to connect to this EJB. It is only meaningful if the EJB has a (remote) Home interface.
The LocalHome interface for the EJB is registered in JNDI at the address specified here. It is only meaningful if the EJB has a LocalHome interface.
The <tssGroup> set of elements is used to contains CORBA security settings (i.e., for EJBs exposed as CORBA objects). It is not necessary if the EJB will not be accessed via CORBA.
All the JNDI reference elements in this section use the Geronimo Naming namespace, which is used to identify the common elements for resolving EJB references, resource references, and Web services references, and is documented here:
Additionally, more information and details about JNDI references can be found here: Global JNDI.
The <abstract-naming-entry> element is not technically a JNDI reference element. It is included in this section because it is an abstract element used for containing these JNDI reference types:
The <naming:ejb-ref> element is used to map EJB references to EJB's in other applications using remote home and remote interface. The application which contains the EJB being referenced should either be in same EAR or should be included in dependency list of this application. Also note as the EJB's referenced are in a different JVM all the client interfaces should also be included in the current application.
The <naming:ejb-local-ref> element is used to map EJB references to EJB's in other applications using local home and local interface. The application which contains the EJB being referenced should either be in same EAR or should be included in dependency list of this application. Also note as the EJB's referenced are in a different JVM all the client interfaces should also be included in the current application.
The <naming:service-ref> is used to map service references to service's in other applications. The application which contains the EJB being referenced should either be in same EAR or should be included in dependency list of this application.
The <naming:resource-ref> element is used to map resource references to resources like JDBC resources, JMS resources, etc. configured outside the current application.
The <naming:resource-env-ref> element is used to map resource references to administrative objects deployed as a part of connectors.
The <naming:message-destination> element is used to map resource references to a message-destination which is used within the deployed EJB application. These are typically a JMS queue or topic which acts like a destination for the messages delivered. Like all the JNDI references in this section, this element will not cause the creation of a message-destination, references an existing message-destination used within the deployed EJB application.
EJB Entity Beans settings can include JNDI names used by remote clients, CMP settings, and CORBA configurations and resolving references.
An EJB session bean represents an interactive session between a single client and an application deployed on the server, and can also include JNDI names used by remote clients, CMP settings, and CORBA configurations and resolving references.
Message-driven bean settings include mapping the MDB to a specific message destination (usually a JMS Topic or Queue), as well as resolving references to other EJBs, resources, or Web services.
The <naming:resource-adapter> XML element uses the Geronimo Naming namespace, which is used to identify the common elements for resolving EJB references, resource references, and Web services references, and is documented here:
The <naming:resource-adapter> element identifies the resource adapter that this message-driven bean connects to. This is typically a JMS server, which is ActiveMQ for the default Geronimo JMS provider. It identifies the resource adapter instance that this MDB should use to connect to its destination. For example, a specific ActiveMQ broker may have several resource adapter instances set up, with different authentication settings, and this identifies the specific instance to use. Like the <naming:cmp-connection-factory>, there are multiple methods available to refer to the ActiveMQ broker. It can be specified by a simple name using the <resource-link> element, by pattern using the <pattern> element, or finally by URL using the <url> element. The resource-link handles most common resource situations (e.g., a JMS resource adapter deployed as part of the same EAR or in the top level of the server), but pattern or URL can be use for any. This might be important if, for example, two resource adapter deployments use the same name, so that the <resource-link> does not uniquely identify one and it must be fully-qualified. This can be used to identify any resource adapter in the same EAR or at the top level in the server. The value specified here should match the <resourceadapter-name> specified for the resource adapter instance in its Geronimo deployment plan.
The <activation-config> XML element is used to specify any configuration data (in the form of name/value pairs) required by the resource adapter in order to supply messages to the MDB. For example:
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