package javax.jms;

/** A <CODE>TopicSession</CODE> object provides methods for creating 
 * <CODE>TopicPublisher</CODE>, <CODE>TopicSubscriber</CODE>, and 
 * <CODE>TemporaryTopic</CODE> objects. It also provides a method for 
 * deleting its client's durable subscribers.
 *
 *<P>A <CODE>TopicSession</CODE> is used for creating Pub/Sub specific
 * objects. In general, use the  <CODE>Session</CODE> object, and 
 *  use <CODE>TopicSession</CODE>  only to support
 * existing code. Using the <CODE>Session</CODE> object simplifies the 
 * programming model, and allows transactions to be used across the two 
 * messaging domains.
 * 
 * <P>A <CODE>TopicSession</CODE> cannot be used to create objects specific to the 
 * point-to-point domain. The following methods inherit from 
 * <CODE>Session</CODE>, but must throw an 
 * <CODE>IllegalStateException</CODE> 
 * if used from <CODE>TopicSession</CODE>:
 *<UL>
 *   <LI><CODE>createBrowser</CODE>
 *   <LI><CODE>createQueue</CODE>
 *   <LI><CODE>createTemporaryQueue</CODE>
 *</UL>
 *
 * @see         javax.jms.Session
 * @see	 javax.jms.Connection#createSession(boolean, int)
 * @see	 javax.jms.TopicConnection#createTopicSession(boolean, int)
 * @see         javax.jms.XATopicSession#getTopicSession()
 */

public interface TopicSession extends Session
{

   /** Creates a topic identity given a <CODE>Topic</CODE> name.
    *
    * <P>This facility is provided for the rare cases where clients need to
    * dynamically manipulate topic identity. This allows the creation of a
    * topic identity with a provider-specific name. Clients that depend 
    * on this ability are not portable.
    *
    * <P>Note that this method is not for creating the physical topic. 
    * The physical creation of topics is an administrative task and is not
    * to be initiated by the JMS API. The one exception is the
    * creation of temporary topics, which is accomplished with the 
    * <CODE>createTemporaryTopic</CODE> method.
    *  
    * @param topicName the name of this <CODE>Topic</CODE>
    *
    * @return a <CODE>Topic</CODE> with the given name
    *
    * @exception JMSException if the session fails to create a topic
    *                         due to some internal error.
    */

   Topic createTopic(String topicName) throws JMSException;

   /** Creates a nondurable subscriber to the specified topic.
    *  
    * <P>A client uses a <CODE>TopicSubscriber</CODE> object to receive 
    * messages that have been published to a topic.
    *
    * <P>Regular <CODE>TopicSubscriber</CODE> objects are not durable. 
    * They receive only messages that are published while they are active.
    *
    * <P>In some cases, a connection may both publish and subscribe to a 
    * topic. The subscriber <CODE>NoLocal</CODE> attribute allows a subscriber
    * to inhibit the delivery of messages published by its own connection.
    * The default value for this attribute is false.
    *
    * @param topic the <CODE>Topic</CODE> to subscribe to
    *  
    * @exception JMSException if the session fails to create a subscriber
    *                         due to some internal error.
    * @exception InvalidDestinationException if an invalid topic is specified.
    */

   TopicSubscriber createSubscriber(Topic topic) throws JMSException;

   /** Creates a nondurable subscriber to the specified topic, using a
    * message selector or specifying whether messages published by its
    * own connection should be delivered to it.
    *
    * <P>A client uses a <CODE>TopicSubscriber</CODE> object to receive 
    * messages that have been published to a topic.
    *  
    * <P>Regular <CODE>TopicSubscriber</CODE> objects are not durable. 
    * They receive only messages that are published while they are active.
    *
    * <P>Messages filtered out by a subscriber's message selector will 
    * never be delivered to the subscriber. From the subscriber's 
    * perspective, they do not exist.
    *
    * <P>In some cases, a connection may both publish and subscribe to a 
    * topic. The subscriber <CODE>NoLocal</CODE> attribute allows a subscriber
    * to inhibit the delivery of messages published by its own connection.
    * The default value for this attribute is false.
    *
    * @param topic the <CODE>Topic</CODE> to subscribe to
    * @param messageSelector only messages with properties matching the
    * message selector expression are delivered. A value of null or
    * an empty string indicates that there is no message selector 
    * for the message consumer.
    * @param noLocal if set, inhibits the delivery of messages published
    * by its own connection
    * 
    * @exception JMSException if the session fails to create a subscriber
    *                         due to some internal error.
    * @exception InvalidDestinationException if an invalid topic is specified.
    * @exception InvalidSelectorException if the message selector is invalid.
    */

   TopicSubscriber createSubscriber(Topic topic, String messageSelector, boolean noLocal) throws JMSException;

   /** Creates a durable subscriber to the specified topic.
    *  
    * <P>If a client needs to receive all the messages published on a 
    * topic, including the ones published while the subscriber is inactive,
    * it uses a durable <CODE>TopicSubscriber</CODE>. The JMS provider
    * retains a record of this 
    * durable subscription and insures that all messages from the topic's 
    * publishers are retained until they are acknowledged by this 
    * durable subscriber or they have expired.
    *
    * <P>Sessions with durable subscribers must always provide the same 
    * client identifier. In addition, each client must specify a name that 
    * uniquely identifies (within client identifier) each durable 
    * subscription it creates. Only one session at a time can have a 
    * <CODE>TopicSubscriber</CODE> for a particular durable subscription.
    *
    * <P>A client can change an existing durable subscription by creating 
    * a durable <CODE>TopicSubscriber</CODE> with the same name and a new 
    * topic and/or 
    * message selector. Changing a durable subscriber is equivalent to 
    * unsubscribing (deleting) the old one and creating a new one.
    *
    * <P>In some cases, a connection may both publish and subscribe to a 
    * topic. The subscriber <CODE>NoLocal</CODE> attribute allows a subscriber
    * to inhibit the delivery of messages published by its own connection.
    * The default value for this attribute is false.
    *
    * @param topic the non-temporary <CODE>Topic</CODE> to subscribe to
    * @param name the name used to identify this subscription
    *  
    * @exception JMSException if the session fails to create a subscriber
    *                         due to some internal error.
    * @exception InvalidDestinationException if an invalid topic is specified.
    */

   TopicSubscriber createDurableSubscriber(Topic topic, String name) throws JMSException;

   /** Creates a durable subscriber to the specified topic, using a
    * message selector or specifying whether messages published by its
    * own connection should be delivered to it.
    *  
    * <P>If a client needs to receive all the messages published on a 
    * topic, including the ones published while the subscriber is inactive,
    * it uses a durable <CODE>TopicSubscriber</CODE>. The JMS provider
    * retains a record of this 
    * durable subscription and insures that all messages from the topic's 
    * publishers are retained until they are acknowledged by this 
    * durable subscriber or they have expired.
    *
    * <P>Sessions with durable subscribers must always provide the same
    * client identifier. In addition, each client must specify a name which
    * uniquely identifies (within client identifier) each durable
    * subscription it creates. Only one session at a time can have a
    * <CODE>TopicSubscriber</CODE> for a particular durable subscription.
    * An inactive durable subscriber is one that exists but
    * does not currently have a message consumer associated with it.
    *
    * <P>A client can change an existing durable subscription by creating 
    * a durable <CODE>TopicSubscriber</CODE> with the same name and a new 
    * topic and/or 
    * message selector. Changing a durable subscriber is equivalent to 
    * unsubscribing (deleting) the old one and creating a new one.
    *
    * @param topic the non-temporary <CODE>Topic</CODE> to subscribe to
    * @param name the name used to identify this subscription
    * @param messageSelector only messages with properties matching the
    * message selector expression are delivered.  A value of null or
    * an empty string indicates that there is no message selector 
    * for the message consumer.
    * @param noLocal if set, inhibits the delivery of messages published
    * by its own connection
    *  
    * @exception JMSException if the session fails to create a subscriber
    *                         due to some internal error.
    * @exception InvalidDestinationException if an invalid topic is specified.
    * @exception InvalidSelectorException if the message selector is invalid.
    */

   TopicSubscriber createDurableSubscriber(Topic topic, String name, String messageSelector, boolean noLocal)
         throws JMSException;

   /** Creates a publisher for the specified topic.
    *
    * <P>A client uses a <CODE>TopicPublisher</CODE> object to publish 
    * messages on a topic.
    * Each time a client creates a <CODE>TopicPublisher</CODE> on a topic, it
    * defines a 
    * new sequence of messages that have no ordering relationship with the 
    * messages it has previously sent.
    *
    * @param topic the <CODE>Topic</CODE> to publish to, or null if this is an
    * unidentified producer
    *
    * @exception JMSException if the session fails to create a publisher
    *                         due to some internal error.
    * @exception InvalidDestinationException if an invalid topic is specified.
    */

   TopicPublisher createPublisher(Topic topic) throws JMSException;

   /** Creates a <CODE>TemporaryTopic</CODE> object. Its lifetime will be that 
    * of the <CODE>TopicConnection</CODE> unless it is deleted earlier.
    *
    * @return a temporary topic identity
    *
    * @exception JMSException if the session fails to create a temporary
    *                         topic due to some internal error.
    */

   TemporaryTopic createTemporaryTopic() throws JMSException;

   /** Unsubscribes a durable subscription that has been created by a client.
    *  
    * <P>This method deletes the state being maintained on behalf of the 
    * subscriber by its provider.
    *
    * <P>It is erroneous for a client to delete a durable subscription
    * while there is an active <CODE>TopicSubscriber</CODE> for the 
    * subscription, or while a consumed message is part of a pending 
    * transaction or has not been acknowledged in the session.
    *
    * @param name the name used to identify this subscription
    *  
    * @exception JMSException if the session fails to unsubscribe to the 
    *                         durable subscription due to some internal error.
    * @exception InvalidDestinationException if an invalid subscription name
    *                                        is specified.
    */

   void unsubscribe(String name) throws JMSException;
}
