package javax.jms;

import javax.transaction.xa.XAResource;

/** The <CODE>XASession</CODE> interface extends the capability of 
 * <CODE>Session</CODE> by adding access to a JMS provider's support for the
 * Java Transaction API (JTA) (optional). This support takes the form of a 
 * <CODE>javax.transaction.xa.XAResource</CODE> object. The functionality of 
 * this object closely resembles that defined by the standard X/Open XA 
 * Resource interface.
 *
 * <P>An application server controls the transactional assignment of an 
 * <CODE>XASession</CODE> by obtaining its <CODE>XAResource</CODE>. It uses 
 * the <CODE>XAResource</CODE> to assign the session to a transaction, prepare 
 * and commit work on the transaction, and so on.
 *
 * <P>An <CODE>XAResource</CODE> provides some fairly sophisticated facilities 
 * for interleaving work on multiple transactions, recovering a list of 
 * transactions in progress, and so on. A JTA aware JMS provider must fully 
 * implement this functionality. This could be done by using the services 
 * of a database that supports XA, or a JMS provider may choose to implement 
 * this functionality from scratch.
 *
 * <P>A client of the application server is given what it thinks is a 
 * regular JMS <CODE>Session</CODE>. Behind the scenes, the application server 
 * controls the transaction management of the underlying 
 * <CODE>XASession</CODE>.
 *
 * <P>The <CODE>XASession</CODE> interface is optional.  JMS providers 
 * are not required to support this interface. This interface is for 
 * use by JMS providers to support transactional environments. 
 * Client programs are strongly encouraged to use the transactional support
 * available in their environment, rather than use these XA
 * interfaces directly. 
 *
 * @see         javax.jms.Session
 */

public interface XASession extends Session
{

   /** Gets the session associated with this <CODE>XASession</CODE>.
    *  
    * @return the  session object
    *  
    * @exception JMSException if an internal error occurs.
    *
    * @since 1.1
    */

   Session getSession() throws JMSException;

   /** Returns an XA resource to the caller.
    *
    * @return an XA resource to the caller
    */

   XAResource getXAResource();

   /** Indicates whether the session is in transacted mode.
    *  
    * @return true
    *  
    * @exception JMSException if the JMS provider fails to return the 
    *                         transaction mode due to some internal error.
    */

   boolean getTransacted() throws JMSException;

   /** Throws a <CODE>TransactionInProgressException</CODE>, since it should 
    * not be called for an <CODE>XASession</CODE> object.
    *
    * @exception TransactionInProgressException if the method is called on 
    *                         an <CODE>XASession</CODE>.
    *                                     
    */

   void commit() throws JMSException;

   /** Throws a <CODE>TransactionInProgressException</CODE>, since it should 
    * not be called for an <CODE>XASession</CODE> object.
    *
    * @exception TransactionInProgressException if the method is called on 
    *                         an <CODE>XASession</CODE>.
    *                                     
    */

   void rollback() throws JMSException;
}
