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package javax.resource.spi;

import javax.resource.ResourceException;
import javax.resource.NotSupportedException;
import javax.resource.spi.ActivationSpec;
import javax.resource.spi.endpoint.MessageEndpointFactory;

import javax.transaction.xa.XAResource;

/**
 * This represents a resource adapter instance and contains operations for
 * lifecycle management and message endpoint setup. A concrete implementation
 * of this interface is required to be a JavaBean.
 *
 * @version 1.0
 * @author  Ram Jeyaraman
 */
public interface ResourceAdapter { 

    // lifecycle operations

    /**
     * This is called when a resource adapter instance is bootstrapped. This
     * may be during resource adapter deployment or application server startup.
     * This is a startup notification from the application server, and this 
     * method is called by an application server thread. The application server
     * thread executes in an unspecified context.
     *
     * <p>During this method call a ResourceAdapter JavaBean is
     * responsible for initializing the resource adapter
     * instance. Any exception thrown during this method
     * call causes the application server to abort the bootstrap procedure 
     * for this specific resource adapter instance.
     *
     * @param ctx a bootstrap context containing references to
     * useful facilities that could be used by a resource adapter instance.
     *
     * @throws ResourceAdapterInternalException indicates bootstrap failure.
     * The resource adapter instance is unusable and must be discarded.
     */
    void start(BootstrapContext ctx) throws ResourceAdapterInternalException; 

    /**
     * This is called when a resource adapter instance is undeployed or
     * during application server shutdown. This is a shutdown notification 
     * from the application server, and this method is called by an 
     * application server thread.  The application server
     * thread executes in an unspecified context.
     *
     * <p>During this method call, a ResourceAdapter 
     * JavaBean is responsible for performing an orderly shutdown of the
     * resource adapter instance. Any exception thrown by this 
     * method call does not alter the 
     * processing of the application server shutdown or resource 
     * adapter undeployment that caused this method call. The application 
     * server may log the exception information for error reporting purposes.
     */
    void stop(); 

    // message endpoint setup operations

    /**
     * This is called during the activation of a message endpoint. This causes
     * the resource adapter instance to do the necessary setup (ie., setup
     * message delivery for the message endpoint with a message provider).
     * Note that message delivery to the message endpoint might start even 
     * before this method returns.
     *
     * <p>Endpoint activation is deemed successful only when this method 
     * completes successfully without throwing any exceptions.
     *
     * @param endpointFactory a message endpoint factory instance.
     *
     * @param spec an activation spec JavaBean instance.
     *
     * @throws NotSupportedException indicates message endpoint 
     * activation rejection due to incorrect activation 
     * setup information.
     */
    void endpointActivation(MessageEndpointFactory endpointFactory, 
            ActivationSpec spec) throws ResourceException;

    /**
     * This is called when a message endpoint is deactivated. The instances
     * passed as arguments to this method call should be identical to those
     * passed in for the corresponding </code>endpointActivation</code> call.
     * This causes the resource adapter to stop delivering messages to the
     * message endpoint. 
     *
     * <p>Any exception thrown by this method is ignored. After
     * this method call, the endpoint is deemed inactive.
     *
     * @param endpointFactory a message endpoint factory instance.
     *
     * @param spec an activation spec JavaBean instance.
     */
    void endpointDeactivation(MessageEndpointFactory endpointFactory, 
            ActivationSpec spec);

    /**
     * This method is called by the application server during crash recovery.
     * This method takes in an array of <code>ActivationSpec</code> JavaBeans 
     * and returns an array of <code>XAResource</code> objects each of which 
     * represents a unique resource manager.
     *
     * The resource adapter may return null if it does not implement the 
     * <code>XAResource</code> interface. Otherwise, it must return an array 
     * of <code>XAResource</code> objects, each of which represents a unique 
     * resource manager that was used by the endpoint applications. 
     * 
     * The application server uses the <code>XAResource</code> objects to 
     * query each resource manager for a list of in-doubt transactions.
     * It then completes each pending transaction by sending the commit 
     * decision to the participating resource managers.
     * 
     * @param specs an array of <code>ActivationSpec</code> JavaBeans each of 
     * which corresponds to an deployed endpoint application that was 
     * active prior to the system crash.
     *
     * @throws ResourceException generic exception if operation fails due to an
     * error condition.
     *
     * @return an array of <code>XAResource</code> objects each of which 
     * represents a unique resource manager.
     */
    XAResource[] getXAResources(ActivationSpec[] specs) 
	throws ResourceException;
}