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Currently Web Beans only runs in JBoss AS 5; integrating the RI into other EE environments (for example another application server like Glassfish), into a servlet container (like Tomcat), or with an Embedded EJB3.1 implementation is fairly easy. In this Appendix we will briefly discuss the steps needed.
The Web Beans SPI is located in the webbeans-spi module, and packaged as webbeans-spi.jar. Some SPIs are optional, if you need to override the default behavior, others are required.
All interfaces in the SPI support the decorator pattern and provide a Forwarding class located in the helpers sub package. Additional, commonly used, utility classes, and standard implementations are also located in the helpers sub package.
/**
* Gets list of all classes in classpath archives with META-INF/beans.xml (or
* for WARs WEB-INF/beans.xml) files
*
* @return An iterable over the classes
*/
public Iterable<Class<?>> discoverWebBeanClasses();
/**
* Gets a list of all deployment descriptors in the app classpath
*
* @return An iterable over the beans.xml files
*/
public Iterable<URL> discoverWebBeansXml();
The discovery of Web Bean classes and beans.xml files is self-explanatory (the algorithm is described in Section 11.1 of the JSR-299 specification, and isn't repeated here).
Web Beans will run without an EJB container; in this case you don't need to implement the EJB SPI.
Web Beans also delegates EJB3 bean discovery to the container so that it doesn't have to scan for EJB3 annotations or parse ejb-jar.xml. For each EJB in the application an EJBDescriptor should be discovered:
public interface EjbDescriptor<T>
{
/**
* Gets the EJB type
*
* @return The EJB Bean class
*/
public Class<T> getType();
/**
* Gets the local business interfaces of the EJB
*
* @return An iterator over the local business interfaces
*/
public Iterable<BusinessInterfaceDescriptor<?>> getLocalBusinessInterfaces();
/**
* Gets the remote business interfaces of the EJB
*
* @return An iterator over the remote business interfaces
*/
public Iterable<BusinessInterfaceDescriptor<?>> getRemoteBusinessInterfaces();
/**
* Get the remove methods of the EJB
*
* @return An iterator over the remove methods
*/
public Iterable<Method> getRemoveMethods();
/**
* Indicates if the bean is stateless
*
* @return True if stateless, false otherwise
*/
public boolean isStateless();
/**
* Indicates if the bean is a EJB 3.1 Singleton
*
* @return True if the bean is a singleton, false otherwise
*/
public boolean isSingleton();
/**
* Indicates if the EJB is stateful
*
* @return True if the bean is stateful, false otherwise
*/
public boolean isStateful();
/**
* Indicates if the EJB is and MDB
*
* @return True if the bean is an MDB, false otherwise
*/
public boolean isMessageDriven();
/**
* Gets the EJB name
*
* @return The name
*/
public String getEjbName();
EjbDescriptor 本身已不解自明並且不需加以說明，它應會依照 EJB 規格中所定義地來回傳相關的 metadata。除了這兩個介面，還有個代表本地商業介面的 BusinessInterfaceDescriptor（包含了使用來查詢某個 EJB instance 的 interface class 以及 jndi 名稱）。
The resolution of @EJB (for injection into simple beans), the resolution of local EJBs (for backing session beans) and remote EJBs (for injection as a Java EE resource) is delegated to the container. You must provide an implementation of org.jboss.webbeans.ejb.spi.EjbServices which provides these operations. For resolving the @EJB injection point, Web Beans will provide the InjectionPoint; for resolving local EJBs, the EjbDescriptor will be provided, and for remote EJBs the jndiName, mappedName, or ejbLink will be provided.
When resolving local EJBs (used to back session beans) a wrapper (SessionObjectReference) around the EJB reference is returned. This wrapper allows Web Beans to request a reference that implements the given business interface, and, in the case of SFSBs, request the removal of the EJB from the container.
Just as EJB resolution is delegated to the container, resolution of @PersistenceContext for injection into simple beans (with the InjectionPoint provided), and resolution of persistence contexts and persistence units (with the unitName provided) for injection as a Java EE resource is delegated to the container.
To allow JPA integration, the JpaServices interface should be implemented.
Web Beans also needs to know what entities are in a deployment (so that they aren't managed by Web Beans). An implementation that detects entities through @Entity and orm.xml is provided by default. If you want to provide support for a entities defined by a JPA provider (such as Hibernate's .hbm.xml you can wrap or replace the default implementation.
EntityDiscovery delegate = bootstrap.getServices().get(EntityDiscovery.class);
Web Beans must delegate JTA activities to the container. The SPI provides a couple hooks to easily achieve this with the TransactionServices interface.
public interface TransactionServices
{
/**
* Possible status conditions for a transaction. This can be used by SPI
* providers to keep track for which status an observer is used.
*/
public static enum Status
{
ALL, SUCCESS, FAILURE
}
/**
* Registers a synchronization object with the currently executing
* transaction.
*
* @see javax.transaction.Synchronization
* @param synchronizedObserver
*/
public void registerSynchronization(Synchronization synchronizedObserver);
/**
* Queries the status of the current execution to see if a transaction is
* currently active.
*
* @return true if a transaction is active
*/
public boolean isTransactionActive();
}
The enumeration Status is a convenience for implementors to be able to keep track of whether a synchronization is supposed to notify an observer only when the transaction is successful, or after a failure, or regardless of the status of the transaction.
Any javax.transaction.Synchronization implementation may be passed to the registerSynchronization() method and the SPI implementation should immediately register the synchronization with the JTA transaction manager used for the EJBs.
To make it easier to determine whether or not a transaction is currently active for the requesting thread, the isTransactionActive() method can be used. The SPI implementation should query the same JTA transaction manager used for the EJBs.
A number of JMS operations are not container specific, and so should be provided via the SPI JmsServices. JMS does not specify how to obtain a ConnectionFactory so the SPI provides a method which should be used to look up a factory. Web Beans also delegates Destination lookup to the container via the SPI.
The resolution of @Resource (for injection into simple beans) and the resolution of resources (for injection as a Java EE resource) is delegated to the container. You must provide an implementation of ResourceServices which provides these operations. For resolving the @Resource injection, Web Beans will provide the InjectionPoint; and for Java EE resources, the jndiName or mappedName will be provided.
The resolution of web service references (for injection as a Java EE resource) is delegated to the container. You must provide an implementation of WebServices whichprovides this operation. For resolving the Java EE resource, the jndiName or mappedName will be provided.
Web Beans uses a map like structure to store bean instances - org.jboss.webbeans.context.api.BeanStore. You may find org.jboss.webbeans.context.api.helpers.ConcurrentHashMapBeanStore useful.
Web Beans expects the Application Server or other container to provide the storage for each application's context. The org.jboss.webbeans.context.api.BeanStore should be implemented to provide an application scoped storage.
The org.jboss.webbeans.bootstrap.api.Bootstrap interface defines the bootstrap for Web Beans. To boot Web Beans, you must obtain an instance of org.jboss.webbeans.bootstrap.WebBeansBootstrap (which implements Boostrap), tell it about the SPIs in use, and then request the container start.
The bootstrap is split into phases, bootstrap initialization and boot and shutdown. Initialization will create a manager, and add the standard (specification defined) contexts. Bootstrap will discover EJBs, classes and XML; add beans defined using annotations; add beans defined using XML; and validate all beans.
The bootstrap supports multiple environments. An environment is defined by an implementation of the Environment interface. A number of standard envrionments are built in as the enumeration Environments. Different environments require different services to be present (for example servlet doesn't require transaction, EJB or JPA services). By default an EE environment is assumed, but you can adjust the environment by calling bootstrap.setEnvironment().
Web Beans uses a generic-typed service registry to allow services to be registered. All services implement the Service interface. The service registry allows services to be added and retrieved.
To initialize the bootstrap you call Bootstrap.initialize(). Before calling initialize(), you must register any services required by your environment. You can do this by calling bootstrap.getServices().add(JpaServices.class, new MyJpaServices()). You must also provide the application context bean store.
Having called initialize(), the Manager can be obtained by calling Bootstrap.getManager().
To boot the container you call Bootstrap.boot().
To shutdown the container you call Bootstrap.shutdown() or webBeansManager.shutdown(). This allows the container to perform any cleanup operations needed.
Web Beans delegates all JNDI operations to the container through the SPI.
A number of the SPI interface require JNDI lookup, and the class AbstractResourceServices provides JNDI/Java EE spec compliant lookup methods.
Web Beans needs to load classes and resources from the classpath at various times. By default, they are loaded from the Thread Context ClassLoader if available, if not the same classloader that was used to load Web Beans, however this may not be correct for some environments. If this is case, you can implement org.jboss.webbeans.spi.ResourceLoader:
public interface ResourceLoader {
/**
* Creates a class from a given FQCN
*
* @param name The name of the clsas
* @return The class
*/
public Class<?> classForName(String name);
/**
* Gets a resource as a URL by name
*
* @param name The name of the resource
* @return An URL to the resource
*/
public URL getResource(String name);
/**
* Gets resources as URLs by name
*
* @param name The name of the resource
* @return An iterable reference to the URLS
*/
public Iterable<URL
> getResources(String name);
}
Java EE / Servlet does not provide any hooks which can be used to provide injection into Servlets, so Web Beans provides an API to allow the container to request JSR-299 injection for a Servlet.
To be compliant with JSR-299, the container should request servlet injection for each newly instantiated servlet after the constructor returns and before the servlet is placed into service.
To perform injection on a servlet call WebBeansManager.injectServlet(). The manager can be obtained from Bootstrap.getManager().
Web Bean RI 對於 container 有些需求以便達到 API 實做之外的正確的功能。
若您要將 Web Bean RI 整合入某個支援多重應用程式建置的環境中，您就必須為各個 Web Bean 應用程式透過自動的方式，或是透過用戶配置來啟用 classloader 隔離。
若您要將 Web Bean 整合入一個 Servlet 環境中，您就必須為各個使用 Servlet 的 Web Bean 應用程式透過自動的方式，或是用戶配置來將 org.jboss.webbeans.servlet.WebBeansListener 註冊為一個 Servlet listener，
If you are integrating the Web Beans into a JSF environment you must register org.jboss.webbeans.jsf.WebBeansPhaseListener as a phase listener, and org.jboss.webbeans.el.WebBeansELREsolver as an EL resolver, either automatically, or through user configuration, for each Web Beans application which uses JSF.
If you are integrating the Web Beans into a JSF environment you must register org.jboss.webbeans.servlet.ConversationPropagationFilter as a Servlet listener, either automatically, or through user configuration, for each Web Beans application which uses JSF. This filter can be registered for all Servlet deployment safely.
Web Beans only supports JSF 1.2 and above.
若您要將 Web Bean 整合入一個 EJB 環境中，您就必須針對於各個使用 enterprise bean 的 Web Bean 應用程式來為應用程式中的所有 EJB 透過自動的方式，或是透過用戶配置來將 org.jboss.webbeans.ejb.SessionBeanInterceptor 註冊為一個 EJB 攔截器。
You must register the SessionBeanInterceptor as the inner most interceptor in the stack for all EJBs.
webbeans-core.jar If you are integrating the Web Beans into an environment that supports deployment of applications, you must insert the webbeans-core.jar into the applications isolated classloader. It cannot be loaded from a shared classloader.
You should bind a Reference to the Manager ObjectFactory into JNDI at java:app/Manager. The type should be javax.inject.manager.Manager and the factory class is org.jboss.webbeans.resources.ManagerObjectFactory