/*
* The contents of this file are subject to the terms
* of the Common Development and Distribution License
* (the License). You may not use this file except in
* compliance with the License.
*
* You can obtain a copy of the license at
* https://glassfish.dev.java.net/public/CDDLv1.0.html or
* glassfish/bootstrap/legal/CDDLv1.0.txt.
* See the License for the specific language governing
* permissions and limitations under the License.
*
* When distributing Covered Code, include this CDDL
* Header Notice in each file and include the License file
* at glassfish/bootstrap/legal/CDDLv1.0.txt.
* If applicable, add the following below the CDDL Header,
* with the fields enclosed by brackets [] replaced by
* you own identifying information:
* "Portions Copyrighted [year] [name of copyright owner]"
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
*/
package javax.jms;
import java.util.Enumeration;
import java.util.Properties;
/** The <CODE>Message</CODE> interface is the root interface of all JMS
* messages. It defines the message header and the <CODE>acknowledge</CODE>
* method used for all messages.
*
* <P>Most message-oriented middleware (MOM) products treat messages as
* lightweight entities that consist
* of a header and a payload. The header contains fields used for message
* routing and identification; the payload contains the application data
* being sent.
*
* <P>Within this general form, the definition of a message varies
* significantly across products. It would be quite difficult for the JMS API
* to support all of these message models.
*
* <P>With this in mind, the JMS message model has the following goals:
* <UL>
* <LI>Provide a single, unified message API
* <LI>Provide an API suitable for creating messages that match the
* format used by provider-native messaging applications
* <LI>Support the development of heterogeneous applications that span
* operating systems, machine architectures, and computer languages
* <LI>Support messages containing objects in the Java programming language
* ("Java objects")
* <LI>Support messages containing Extensible Markup Language (XML) pages
* </UL>
*
* <P>JMS messages are composed of the following parts:
* <UL>
* <LI>Header - All messages support the same set of header fields.
* Header fields contain values used by both clients and providers to
* identify and route messages.
* <LI>Properties - Each message contains a built-in facility for supporting
* application-defined property values. Properties provide an efficient
* mechanism for supporting application-defined message filtering.
* <LI>Body - The JMS API defines several types of message body, which cover
* the majority of messaging styles currently in use.
* </UL>
*
* <H4>Message Bodies</H4>
*
* <P>The JMS API defines five types of message body:
* <UL>
* <LI>Stream - A <CODE>StreamMessage</CODE> object's message body contains
* a stream of primitive values in the Java programming
* language ("Java primitives"). It is filled and read sequentially.
* <LI>Map - A <CODE>MapMessage</CODE> object's message body contains a set
* of name-value pairs, where names are <CODE>String</CODE>
* objects, and values are Java primitives. The entries can be accessed
* sequentially or randomly by name. The order of the entries is
* undefined.
* <LI>Text - A <CODE>TextMessage</CODE> object's message body contains a
* <CODE>java.lang.String</CODE> object. This message type can be used
* to transport plain-text messages, and XML messages.
* <LI>Object - An <CODE>ObjectMessage</CODE> object's message body contains
* a <CODE>Serializable</CODE> Java object.
* <LI>Bytes - A <CODE>BytesMessage</CODE> object's message body contains a
* stream of uninterpreted bytes. This message type is for
* literally encoding a body to match an existing message format. In
* many cases, it is possible to use one of the other body types,
* which are easier to use. Although the JMS API allows the use of
* message properties with byte messages, they are typically not used,
* since the inclusion of properties may affect the format.
* </UL>
*
* <H4>Message Headers</H4>
*
* <P>The <CODE>JMSCorrelationID</CODE> header field is used for linking one
* message with
* another. It typically links a reply message with its requesting message.
*
* <P><CODE>JMSCorrelationID</CODE> can hold a provider-specific message ID,
* an application-specific <CODE>String</CODE> object, or a provider-native
* <CODE>byte[]</CODE> value.
*
* <H4>Message Properties</H4>
*
* <P>A <CODE>Message</CODE> object contains a built-in facility for supporting
* application-defined property values. In effect, this provides a mechanism
* for adding application-specific header fields to a message.
*
* <P>Properties allow an application, via message selectors, to have a JMS
* provider select, or filter, messages on its behalf using
* application-specific criteria.
*
* <P>Property names must obey the rules for a message selector identifier.
* Property names must not be null, and must not be empty strings. If a property
* name is set and it is either null or an empty string, an
* <CODE>IllegalArgumentException</CODE> must be thrown.
*
* <P>Property values can be <CODE>boolean</CODE>, <CODE>byte</CODE>,
* <CODE>short</CODE>, <CODE>int</CODE>, <CODE>long</CODE>, <CODE>float</CODE>,
* <CODE>double</CODE>, and <CODE>String</CODE>.
*
* <P>Property values are set prior to sending a message. When a client
* receives a message, its properties are in read-only mode. If a
* client attempts to set properties at this point, a
* <CODE>MessageNotWriteableException</CODE> is thrown. If
* <CODE>clearProperties</CODE> is called, the properties can now be both
* read from and written to. Note that header fields are distinct from
* properties. Header fields are never in read-only mode.
*
* <P>A property value may duplicate a value in a message's body, or it may
* not. Although JMS does not define a policy for what should or should not
* be made a property, application developers should note that JMS providers
* will likely handle data in a message's body more efficiently than data in
* a message's properties. For best performance, applications should use
* message properties only when they need to customize a message's header.
* The primary reason for doing this is to support customized message
* selection.
*
* <P>Message properties support the following conversion table. The marked
* cases must be supported. The unmarked cases must throw a
* <CODE>JMSException</CODE>. The <CODE>String</CODE>-to-primitive conversions
* may throw a runtime exception if the
* primitive's <CODE>valueOf</CODE> method does not accept the
* <CODE>String</CODE> as a valid representation of the primitive.
*
* <P>A value written as the row type can be read as the column type.
*
* <PRE>
* | | boolean byte short int long float double String
* |----------------------------------------------------------
* |boolean | X X
* |byte | X X X X X
* |short | X X X X
* |int | X X X
* |long | X X
* |float | X X X
* |double | X X
* |String | X X X X X X X X
* |----------------------------------------------------------
* </PRE>
*
* <P>In addition to the type-specific set/get methods for properties, JMS
* provides the <CODE>setObjectProperty</CODE> and
* <CODE>getObjectProperty</CODE> methods. These support the same set of
* property types using the objectified primitive values. Their purpose is
* to allow the decision of property type to made at execution time rather
* than at compile time. They support the same property value conversions.
*
* <P>The <CODE>setObjectProperty</CODE> method accepts values of class
* <CODE>Boolean</CODE>, <CODE>Byte</CODE>, <CODE>Short</CODE>,
* <CODE>Integer</CODE>, <CODE>Long</CODE>, <CODE>Float</CODE>,
* <CODE>Double</CODE>, and <CODE>String</CODE>. An attempt
* to use any other class must throw a <CODE>JMSException</CODE>.
*
* <P>The <CODE>getObjectProperty</CODE> method only returns values of class
* <CODE>Boolean</CODE>, <CODE>Byte</CODE>, <CODE>Short</CODE>,
* <CODE>Integer</CODE>, <CODE>Long</CODE>, <CODE>Float</CODE>,
* <CODE>Double</CODE>, and <CODE>String</CODE>.
*
* <P>The order of property values is not defined. To iterate through a
* message's property values, use <CODE>getPropertyNames</CODE> to retrieve
* a property name enumeration and then use the various property get methods
* to retrieve their values.
*
* <P>A message's properties are deleted by the <CODE>clearProperties</CODE>
* method. This leaves the message with an empty set of properties.
*
* <P>Getting a property value for a name which has not been set returns a
* null value. Only the <CODE>getStringProperty</CODE> and
* <CODE>getObjectProperty</CODE> methods can return a null value.
* Attempting to read a null value as a primitive type must be treated as
* calling the primitive's corresponding <CODE>valueOf(String)</CODE>
* conversion method with a null value.
*
* <P>The JMS API reserves the <CODE>JMSX</CODE> property name prefix for JMS
* defined properties.
* The full set of these properties is defined in the Java Message Service
* specification. New JMS defined properties may be added in later versions
* of the JMS API. Support for these properties is optional. The
* <CODE>String[] ConnectionMetaData.getJMSXPropertyNames</CODE> method
* returns the names of the JMSX properties supported by a connection.
*
* <P>JMSX properties may be referenced in message selectors whether or not
* they are supported by a connection. If they are not present in a
* message, they are treated like any other absent property.
*
* <P>JMSX properties defined in the specification as "set by provider on
* send" are available to both the producer and the consumers of the message.
* JMSX properties defined in the specification as "set by provider on
* receive" are available only to the consumers.
*
* <P><CODE>JMSXGroupID</CODE> and <CODE>JMSXGroupSeq</CODE> are standard
* properties that clients
* should use if they want to group messages. All providers must support them.
* Unless specifically noted, the values and semantics of the JMSX properties
* are undefined.
*
* <P>The JMS API reserves the <CODE>JMS_<I>vendor_name</I></CODE> property
* name prefix for provider-specific properties. Each provider defines its own
* value for <CODE><I>vendor_name</I></CODE>. This is the mechanism a JMS
* provider uses to make its special per-message services available to a JMS
* client.
*
* <P>The purpose of provider-specific properties is to provide special
* features needed to integrate JMS clients with provider-native clients in a
* single JMS application. They should not be used for messaging between JMS
* clients.
*
* <H4>Provider Implementations of JMS Message Interfaces</H4>
*
* <P>The JMS API provides a set of message interfaces that define the JMS
* message
* model. It does not provide implementations of these interfaces.
*
* <P>Each JMS provider supplies a set of message factories with its
* <CODE>Session</CODE> object for creating instances of messages. This allows
* a provider to use message implementations tailored to its specific needs.
*
* <P>A provider must be prepared to accept message implementations that are
* not its own. They may not be handled as efficiently as its own
* implementation; however, they must be handled.
*
* <P>Note the following exception case when a provider is handling a foreign
* message implementation. If the foreign message implementation contains a
* <CODE>JMSReplyTo</CODE> header field that is set to a foreign destination
* implementation, the provider is not required to handle or preserve the
* value of this header field.
*
* <H4>Message Selectors</H4>
*
* <P>A JMS message selector allows a client to specify, by
* header field references and property references, the
* messages it is interested in. Only messages whose header
* and property values
* match the
* selector are delivered. What it means for a message not to be delivered
* depends on the <CODE>MessageConsumer</CODE> being used (see
* {@link javax.jms.QueueReceiver QueueReceiver} and
* {@link javax.jms.TopicSubscriber TopicSubscriber}).
*
* <P>Message selectors cannot reference message body values.
*
* <P>A message selector matches a message if the selector evaluates to
* true when the message's header field values and property values are
* substituted for their corresponding identifiers in the selector.
*
* <P>A message selector is a <CODE>String</CODE> whose syntax is based on a
* subset of
* the SQL92 conditional expression syntax. If the value of a message selector
* is an empty string, the value is treated as a null and indicates that there
* is no message selector for the message consumer.
*
* <P>The order of evaluation of a message selector is from left to right
* within precedence level. Parentheses can be used to change this order.
*
* <P>Predefined selector literals and operator names are shown here in
* uppercase; however, they are case insensitive.
*
* <P>A selector can contain:
*
* <UL>
* <LI>Literals:
* <UL>
* <LI>A string literal is enclosed in single quotes, with a single quote
* represented by doubled single quote; for example,
* <CODE>'literal'</CODE> and <CODE>'literal''s'</CODE>. Like
* string literals in the Java programming language, these use the
* Unicode character encoding.
* <LI>An exact numeric literal is a numeric value without a decimal
* point, such as <CODE>57</CODE>, <CODE>-957</CODE>, and
* <CODE>+62</CODE>; numbers in the range of <CODE>long</CODE> are
* supported. Exact numeric literals use the integer literal
* syntax of the Java programming language.
* <LI>An approximate numeric literal is a numeric value in scientific
* notation, such as <CODE>7E3</CODE> and <CODE>-57.9E2</CODE>, or a
* numeric value with a decimal, such as <CODE>7.</CODE>,
* <CODE>-95.7</CODE>, and <CODE>+6.2</CODE>; numbers in the range of
* <CODE>double</CODE> are supported. Approximate literals use the
* floating-point literal syntax of the Java programming language.
* <LI>The boolean literals <CODE>TRUE</CODE> and <CODE>FALSE</CODE>.
* </UL>
* <LI>Identifiers:
* <UL>
* <LI>An identifier is an unlimited-length sequence of letters
* and digits, the first of which must be a letter. A letter is any
* character for which the method <CODE>Character.isJavaLetter</CODE>
* returns true. This includes <CODE>'_'</CODE> and <CODE>'$'</CODE>.
* A letter or digit is any character for which the method
* <CODE>Character.isJavaLetterOrDigit</CODE> returns true.
* <LI>Identifiers cannot be the names <CODE>NULL</CODE>,
* <CODE>TRUE</CODE>, and <CODE>FALSE</CODE>.
* <LI>Identifiers cannot be <CODE>NOT</CODE>, <CODE>AND</CODE>,
* <CODE>OR</CODE>, <CODE>BETWEEN</CODE>, <CODE>LIKE</CODE>,
* <CODE>IN</CODE>, <CODE>IS</CODE>, or <CODE>ESCAPE</CODE>.
* <LI>Identifiers are either header field references or property
* references. The type of a property value in a message selector
* corresponds to the type used to set the property. If a property
* that does not exist in a message is referenced, its value is
* <CODE>NULL</CODE>.
* <LI>The conversions that apply to the get methods for properties do not
* apply when a property is used in a message selector expression.
* For example, suppose you set a property as a string value, as in the
* following:
* <PRE>myMessage.setStringProperty("NumberOfOrders", "2");</PRE>
* The following expression in a message selector would evaluate to
* false, because a string cannot be used in an arithmetic expression:
* <PRE>"NumberOfOrders > 1"</PRE>
* <LI>Identifiers are case-sensitive.
* <LI>Message header field references are restricted to
* <CODE>JMSDeliveryMode</CODE>, <CODE>JMSPriority</CODE>,
* <CODE>JMSMessageID</CODE>, <CODE>JMSTimestamp</CODE>,
* <CODE>JMSCorrelationID</CODE>, and <CODE>JMSType</CODE>.
* <CODE>JMSMessageID</CODE>, <CODE>JMSCorrelationID</CODE>, and
* <CODE>JMSType</CODE> values may be null and if so are treated as a
* <CODE>NULL</CODE> value.
* <LI>Any name beginning with <CODE>'JMSX'</CODE> is a JMS defined
* property name.
* <LI>Any name beginning with <CODE>'JMS_'</CODE> is a provider-specific
* property name.
* <LI>Any name that does not begin with <CODE>'JMS'</CODE> is an
* application-specific property name.
* </UL>
* <LI>White space is the same as that defined for the Java programming
* language: space, horizontal tab, form feed, and line terminator.
* <LI>Expressions:
* <UL>
* <LI>A selector is a conditional expression; a selector that evaluates
* to <CODE>true</CODE> matches; a selector that evaluates to
* <CODE>false</CODE> or unknown does not match.
* <LI>Arithmetic expressions are composed of themselves, arithmetic
* operations, identifiers (whose value is treated as a numeric
* literal), and numeric literals.
* <LI>Conditional expressions are composed of themselves, comparison
* operations, and logical operations.
* </UL>
* <LI>Standard bracketing <CODE>()</CODE> for ordering expression evaluation
* is supported.
* <LI>Logical operators in precedence order: <CODE>NOT</CODE>,
* <CODE>AND</CODE>, <CODE>OR</CODE>
* <LI>Comparison operators: <CODE>=</CODE>, <CODE>></CODE>, <CODE>>=</CODE>,
* <CODE><</CODE>, <CODE><=</CODE>, <CODE><></CODE> (not equal)
* <UL>
* <LI>Only like type values can be compared. One exception is that it
* is valid to compare exact numeric values and approximate numeric
* values; the type conversion required is defined by the rules of
* numeric promotion in the Java programming language. If the
* comparison of non-like type values is attempted, the value of the
* operation is false. If either of the type values evaluates to
* <CODE>NULL</CODE>, the value of the expression is unknown.
* <LI>String and boolean comparison is restricted to <CODE>=</CODE> and
* <CODE><></CODE>. Two strings are equal
* if and only if they contain the same sequence of characters.
* </UL>
* <LI>Arithmetic operators in precedence order:
* <UL>
* <LI><CODE>+</CODE>, <CODE>-</CODE> (unary)
* <LI><CODE>*</CODE>, <CODE>/</CODE> (multiplication and division)
* <LI><CODE>+</CODE>, <CODE>-</CODE> (addition and subtraction)
* <LI>Arithmetic operations must use numeric promotion in the Java
* programming language.
* </UL>
* <LI><CODE><I>arithmetic-expr1</I> [NOT] BETWEEN <I>arithmetic-expr2</I>
* AND <I>arithmetic-expr3</I></CODE> (comparison operator)
* <UL>
* <LI><CODE>"age BETWEEN 15 AND 19"</CODE> is
* equivalent to
* <CODE>"age >= 15 AND age <= 19"</CODE>
* <LI><CODE>"age NOT BETWEEN 15 AND 19"</CODE>
* is equivalent to
* <CODE>"age < 15 OR age > 19"</CODE>
* </UL>
* <LI><CODE><I>identifier</I> [NOT] IN (<I>string-literal1</I>,
* <I>string-literal2</I>,...)</CODE> (comparison operator where
* <CODE><I>identifier</I></CODE> has a <CODE>String</CODE> or
* <CODE>NULL</CODE> value)
* <UL>
* <LI><CODE>"Country IN (' UK', 'US', 'France')"</CODE>
* is true for
* <CODE>'UK'</CODE> and false for <CODE>'Peru'</CODE>; it is
* equivalent to the expression
* <CODE>"(Country = ' UK') OR (Country = ' US') OR (Country = ' France')"</CODE>
* <LI><CODE>"Country NOT IN (' UK', 'US', 'France')"</CODE>
* is false for <CODE>'UK'</CODE> and true for <CODE>'Peru'</CODE>; it
* is equivalent to the expression
* <CODE>"NOT ((Country = ' UK') OR (Country = ' US') OR (Country = ' France'))"</CODE>
* <LI>If identifier of an <CODE>IN</CODE> or <CODE>NOT IN</CODE>
* operation is <CODE>NULL</CODE>, the value of the operation is
* unknown.
* </UL>
* <LI><CODE><I>identifier</I> [NOT] LIKE <I>pattern-value</I> [ESCAPE
* <I>escape-character</I>]</CODE> (comparison operator, where
* <CODE><I>identifier</I></CODE> has a <CODE>String</CODE> value;
* <CODE><I>pattern-value</I></CODE> is a string literal where
* <CODE>'_'</CODE> stands for any single character; <CODE>'%'</CODE>
* stands for any sequence of characters, including the empty sequence;
* and all other characters stand for themselves. The optional
* <CODE><I>escape-character</I></CODE> is a single-character string
* literal whose character is used to escape the special meaning of the
* <CODE>'_'</CODE> and <CODE>'%'</CODE> in
* <CODE><I>pattern-value</I></CODE>.)
* <UL>
* <LI><CODE>"phone LIKE '12%3'"</CODE> is true for
* <CODE>'123'</CODE> or <CODE>'12993'</CODE> and false for
* <CODE>'1234'</CODE>
* <LI><CODE>"word LIKE 'l_se'"</CODE> is true for
* <CODE>'lose'</CODE> and false for <CODE>'loose'</CODE>
* <LI><CODE>"underscored LIKE '\_%' ESCAPE '\'"</CODE>
* is true for <CODE>'_foo'</CODE> and false for <CODE>'bar'</CODE>
* <LI><CODE>"phone NOT LIKE '12%3'"</CODE> is false for
* <CODE>'123'</CODE> or <CODE>'12993'</CODE> and true for
* <CODE>'1234'</CODE>
* <LI>If <CODE><I>identifier</I></CODE> of a <CODE>LIKE</CODE> or
* <CODE>NOT LIKE</CODE> operation is <CODE>NULL</CODE>, the value
* of the operation is unknown.
* </UL>
* <LI><CODE><I>identifier</I> IS NULL</CODE> (comparison operator that tests
* for a null header field value or a missing property value)
* <UL>
* <LI><CODE>"prop_name IS NULL"</CODE>
* </UL>
* <LI><CODE><I>identifier</I> IS NOT NULL</CODE> (comparison operator that
* tests for the existence of a non-null header field value or a property
* value)
* <UL>
* <LI><CODE>"prop_name IS NOT NULL"</CODE>
* </UL>
*
* <P>JMS providers are required to verify the syntactic correctness of a
* message selector at the time it is presented. A method that provides a
* syntactically incorrect selector must result in a <CODE>JMSException</CODE>.
* JMS providers may also optionally provide some semantic checking at the time
* the selector is presented. Not all semantic checking can be performed at
* the time a message selector is presented, because property types are not known.
*
* <P>The following message selector selects messages with a message type
* of car and color of blue and weight greater than 2500 pounds:
*
* <PRE>"JMSType = 'car' AND color = 'blue' AND weight > 2500"</PRE>
*
* <H4>Null Values</H4>
*
* <P>As noted above, property values may be <CODE>NULL</CODE>. The evaluation
* of selector expressions containing <CODE>NULL</CODE> values is defined by
* SQL92 <CODE>NULL</CODE> semantics. A brief description of these semantics
* is provided here.
*
* <P>SQL treats a <CODE>NULL</CODE> value as unknown. Comparison or arithmetic
* with an unknown value always yields an unknown value.
*
* <P>The <CODE>IS NULL</CODE> and <CODE>IS NOT NULL</CODE> operators convert
* an unknown value into the respective <CODE>TRUE</CODE> and
* <CODE>FALSE</CODE> values.
*
* <P>The boolean operators use three-valued logic as defined by the
* following tables:
*
* <P><B>The definition of the <CODE>AND</CODE> operator</B>
*
* <PRE>
* | AND | T | F | U
* +------+-------+-------+-------
* | T | T | F | U
* | F | F | F | F
* | U | U | F | U
* +------+-------+-------+-------
* </PRE>
*
* <P><B>The definition of the <CODE>OR</CODE> operator</B>
*
* <PRE>
* | OR | T | F | U
* +------+-------+-------+--------
* | T | T | T | T
* | F | T | F | U
* | U | T | U | U
* +------+-------+-------+-------
* </PRE>
*
* <P><B>The definition of the <CODE>NOT</CODE> operator</B>
*
* <PRE>
* | NOT
* +------+------
* | T | F
* | F | T
* | U | U
* +------+-------
* </PRE>
*
* <H4>Special Notes</H4>
*
* <P>When used in a message selector, the <CODE>JMSDeliveryMode</CODE> header
* field is treated as having the values <CODE>'PERSISTENT'</CODE> and
* <CODE>'NON_PERSISTENT'</CODE>.
*
* <P>Date and time values should use the standard <CODE>long</CODE>
* millisecond value. When a date or time literal is included in a message
* selector, it should be an integer literal for a millisecond value. The
* standard way to produce millisecond values is to use
* <CODE>java.util.Calendar</CODE>.
*
* <P>Although SQL supports fixed decimal comparison and arithmetic, JMS
* message selectors do not. This is the reason for restricting exact
* numeric literals to those without a decimal (and the addition of
* numerics with a decimal as an alternate representation for
* approximate numeric values).
*
* <P>SQL comments are not supported.
*
* @version 1.1 April 2, 2002
* @author Mark Hapner
* @author Rich Burridge
* @author Kate Stout
*
* @see javax.jms.MessageConsumer#receive()
* @see javax.jms.MessageConsumer#receive(long)
* @see javax.jms.MessageConsumer#receiveNoWait()
* @see javax.jms.MessageListener#onMessage(Message)
* @see javax.jms.BytesMessage
* @see javax.jms.MapMessage
* @see javax.jms.ObjectMessage
* @see javax.jms.StreamMessage
* @see javax.jms.TextMessage
*/
public interface Message {
/** The message producer's default delivery mode is <CODE>PERSISTENT</CODE>.
*
* @see DeliveryMode#PERSISTENT
*/
static final int DEFAULT_DELIVERY_MODE = DeliveryMode.PERSISTENT;
/** The message producer's default priority is 4.
*/
static final int DEFAULT_PRIORITY = 4;
/** The message producer's default time to live is unlimited; the message
* never expires.
*/
static final long DEFAULT_TIME_TO_LIVE = 0;
/** Gets the message ID.
*
* <P>The <CODE>JMSMessageID</CODE> header field contains a value that
* uniquely identifies each message sent by a provider.
*
* <P>When a message is sent, <CODE>JMSMessageID</CODE> can be ignored.
* When the <CODE>send</CODE> or <CODE>publish</CODE> method returns, it
* contains a provider-assigned value.
*
* <P>A <CODE>JMSMessageID</CODE> is a <CODE>String</CODE> value that
* should function as a
* unique key for identifying messages in a historical repository.
* The exact scope of uniqueness is provider-defined. It should at
* least cover all messages for a specific installation of a
* provider, where an installation is some connected set of message
* routers.
*
* <P>All <CODE>JMSMessageID</CODE> values must start with the prefix
* <CODE>'ID:'</CODE>.
* Uniqueness of message ID values across different providers is
* not required.
*
* <P>Since message IDs take some effort to create and increase a
* message's size, some JMS providers may be able to optimize message
* overhead if they are given a hint that the message ID is not used by
* an application. By calling the
* <CODE>MessageProducer.setDisableMessageID</CODE> method, a JMS client
* enables this potential optimization for all messages sent by that
* message producer. If the JMS provider accepts this
* hint, these messages must have the message ID set to null; if the
* provider ignores the hint, the message ID must be set to its normal
* unique value.
*
* @return the message ID
*
* @exception JMSException if the JMS provider fails to get the message ID
* due to some internal error.
* @see javax.jms.Message#setJMSMessageID(String)
* @see javax.jms.MessageProducer#setDisableMessageID(boolean)
*/
String
getJMSMessageID() throws JMSException;
/** Sets the message ID.
*
* <P>JMS providers set this field when a message is sent. This method
* can be used to change the value for a message that has been received.
*
* @param id the ID of the message
*
* @exception JMSException if the JMS provider fails to set the message ID
* due to some internal error.
*
* @see javax.jms.Message#getJMSMessageID()
*/
void
setJMSMessageID(String id) throws JMSException;
/** Gets the message timestamp.
*
* <P>The <CODE>JMSTimestamp</CODE> header field contains the time a
* message was
* handed off to a provider to be sent. It is not the time the
* message was actually transmitted, because the actual send may occur
* later due to transactions or other client-side queueing of messages.
*
* <P>When a message is sent, <CODE>JMSTimestamp</CODE> is ignored. When
* the <CODE>send</CODE> or <CODE>publish</CODE>
* method returns, it contains a time value somewhere in the interval
* between the call and the return. The value is in the format of a normal
* millis time value in the Java programming language.
*
* <P>Since timestamps take some effort to create and increase a
* message's size, some JMS providers may be able to optimize message
* overhead if they are given a hint that the timestamp is not used by an
* application. By calling the
* <CODE>MessageProducer.setDisableMessageTimestamp</CODE> method, a JMS
* client enables this potential optimization for all messages sent by
* that message producer. If the JMS provider accepts this
* hint, these messages must have the timestamp set to zero; if the
* provider ignores the hint, the timestamp must be set to its normal
* value.
*
* @return the message timestamp
*
* @exception JMSException if the JMS provider fails to get the timestamp
* due to some internal error.
*
* @see javax.jms.Message#setJMSTimestamp(long)
* @see javax.jms.MessageProducer#setDisableMessageTimestamp(boolean)
*/
long
getJMSTimestamp() throws JMSException;
/** Sets the message timestamp.
*
* <P>JMS providers set this field when a message is sent. This method
* can be used to change the value for a message that has been received.
*
* @param timestamp the timestamp for this message
*
* @exception JMSException if the JMS provider fails to set the timestamp
* due to some internal error.
*
* @see javax.jms.Message#getJMSTimestamp()
*/
void
setJMSTimestamp(long timestamp) throws JMSException;
/** Gets the correlation ID as an array of bytes for the message.
*
* <P>The use of a <CODE>byte[]</CODE> value for
* <CODE>JMSCorrelationID</CODE> is non-portable.
*
* @return the correlation ID of a message as an array of bytes
*
* @exception JMSException if the JMS provider fails to get the correlation
* ID due to some internal error.
*
* @see javax.jms.Message#setJMSCorrelationID(String)
* @see javax.jms.Message#getJMSCorrelationID()
* @see javax.jms.Message#setJMSCorrelationIDAsBytes(byte[])
*/
byte []
getJMSCorrelationIDAsBytes() throws JMSException;
/** Sets the correlation ID as an array of bytes for the message.
*
* <P>The array is copied before the method returns, so
* future modifications to the array will not alter this message header.
*
* <P>If a provider supports the native concept of correlation ID, a
* JMS client may need to assign specific <CODE>JMSCorrelationID</CODE>
* values to match those expected by native messaging clients.
* JMS providers without native correlation ID values are not required to
* support this method and its corresponding get method; their
* implementation may throw a
* <CODE>java.lang.UnsupportedOperationException</CODE>.
*
* <P>The use of a <CODE>byte[]</CODE> value for
* <CODE>JMSCorrelationID</CODE> is non-portable.
*
* @param correlationID the correlation ID value as an array of bytes
*
* @exception JMSException if the JMS provider fails to set the correlation
* ID due to some internal error.
*
* @see javax.jms.Message#setJMSCorrelationID(String)
* @see javax.jms.Message#getJMSCorrelationID()
* @see javax.jms.Message#getJMSCorrelationIDAsBytes()
*/
void
setJMSCorrelationIDAsBytes(byte[] correlationID) throws JMSException;
/** Sets the correlation ID for the message.
*
* <P>A client can use the <CODE>JMSCorrelationID</CODE> header field to
* link one message with another. A typical use is to link a response
* message with its request message.
*
* <P><CODE>JMSCorrelationID</CODE> can hold one of the following:
* <UL>
* <LI>A provider-specific message ID
* <LI>An application-specific <CODE>String</CODE>
* <LI>A provider-native <CODE>byte[]</CODE> value
* </UL>
*
* <P>Since each message sent by a JMS provider is assigned a message ID
* value, it is convenient to link messages via message ID. All message ID
* values must start with the <CODE>'ID:'</CODE> prefix.
*
* <P>In some cases, an application (made up of several clients) needs to
* use an application-specific value for linking messages. For instance,
* an application may use <CODE>JMSCorrelationID</CODE> to hold a value
* referencing some external information. Application-specified values
* must not start with the <CODE>'ID:'</CODE> prefix; this is reserved for
* provider-generated message ID values.
*
* <P>If a provider supports the native concept of correlation ID, a JMS
* client may need to assign specific <CODE>JMSCorrelationID</CODE> values
* to match those expected by clients that do not use the JMS API. A
* <CODE>byte[]</CODE> value is used for this
* purpose. JMS providers without native correlation ID values are not
* required to support <CODE>byte[]</CODE> values. The use of a
* <CODE>byte[]</CODE> value for <CODE>JMSCorrelationID</CODE> is
* non-portable.
*
* @param correlationID the message ID of a message being referred to
*
* @exception JMSException if the JMS provider fails to set the correlation
* ID due to some internal error.
*
* @see javax.jms.Message#getJMSCorrelationID()
* @see javax.jms.Message#getJMSCorrelationIDAsBytes()
* @see javax.jms.Message#setJMSCorrelationIDAsBytes(byte[])
*/
void
setJMSCorrelationID(String correlationID) throws JMSException;
/** Gets the correlation ID for the message.
*
* <P>This method is used to return correlation ID values that are
* either provider-specific message IDs or application-specific
* <CODE>String</CODE> values.
*
* @return the correlation ID of a message as a <CODE>String</CODE>
*
* @exception JMSException if the JMS provider fails to get the correlation
* ID due to some internal error.
*
* @see javax.jms.Message#setJMSCorrelationID(String)
* @see javax.jms.Message#getJMSCorrelationIDAsBytes()
* @see javax.jms.Message#setJMSCorrelationIDAsBytes(byte[])
*/
String
getJMSCorrelationID() throws JMSException;
/** Gets the <CODE>Destination</CODE> object to which a reply to this
* message should be sent.
*
* @return <CODE>Destination</CODE> to which to send a response to this
* message
*
* @exception JMSException if the JMS provider fails to get the
* <CODE>JMSReplyTo</CODE> destination due to some
* internal error.
*
* @see javax.jms.Message#setJMSReplyTo(Destination)
*/
Destination
getJMSReplyTo() throws JMSException;
/** Sets the <CODE>Destination</CODE> object to which a reply to this
* message should be sent.
*
* <P>The <CODE>JMSReplyTo</CODE> header field contains the destination
* where a reply
* to the current message should be sent. If it is null, no reply is
* expected. The destination may be either a <CODE>Queue</CODE> object or
* a <CODE>Topic</CODE> object.
*
* <P>Messages sent with a null <CODE>JMSReplyTo</CODE> value may be a
* notification of some event, or they may just be some data the sender
* thinks is of interest.
*
* <P>Messages with a <CODE>JMSReplyTo</CODE> value typically expect a
* response. A response is optional; it is up to the client to decide.
* These messages are called requests. A message sent in response to a
* request is called a reply.
*
* <P>In some cases a client may wish to match a request it sent earlier
* with a reply it has just received. The client can use the
* <CODE>JMSCorrelationID</CODE> header field for this purpose.
*
* @param replyTo <CODE>Destination</CODE> to which to send a response to
* this message
*
* @exception JMSException if the JMS provider fails to set the
* <CODE>JMSReplyTo</CODE> destination due to some
* internal error.
*
* @see javax.jms.Message#getJMSReplyTo()
*/
void
setJMSReplyTo(Destination replyTo) throws JMSException;
/** Gets the <CODE>Destination</CODE> object for this message.
*
* <P>The <CODE>JMSDestination</CODE> header field contains the
* destination to which the message is being sent.
*
* <P>When a message is sent, this field is ignored. After completion
* of the <CODE>send</CODE> or <CODE>publish</CODE> method, the field
* holds the destination specified by the method.
*
* <P>When a message is received, its <CODE>JMSDestination</CODE> value
* must be equivalent to the value assigned when it was sent.
*
* @return the destination of this message
*
* @exception JMSException if the JMS provider fails to get the destination
* due to some internal error.
*
* @see javax.jms.Message#setJMSDestination(Destination)
*/
Destination
getJMSDestination() throws JMSException;
/** Sets the <CODE>Destination</CODE> object for this message.
*
* <P>JMS providers set this field when a message is sent. This method
* can be used to change the value for a message that has been received.
*
* @param destination the destination for this message
*
* @exception JMSException if the JMS provider fails to set the destination
* due to some internal error.
*
* @see javax.jms.Message#getJMSDestination()
*/
void
setJMSDestination(Destination destination) throws JMSException;
/** Gets the <CODE>DeliveryMode</CODE> value specified for this message.
*
* @return the delivery mode for this message
*
* @exception JMSException if the JMS provider fails to get the
* delivery mode due to some internal error.
*
* @see javax.jms.Message#setJMSDeliveryMode(int)
* @see javax.jms.DeliveryMode
*/
int
getJMSDeliveryMode() throws JMSException;
/** Sets the <CODE>DeliveryMode</CODE> value for this message.
*
* <P>JMS providers set this field when a message is sent. This method
* can be used to change the value for a message that has been received.
*
* @param deliveryMode the delivery mode for this message
*
* @exception JMSException if the JMS provider fails to set the
* delivery mode due to some internal error.
*
* @see javax.jms.Message#getJMSDeliveryMode()
* @see javax.jms.DeliveryMode
*/
void
setJMSDeliveryMode(int deliveryMode) throws JMSException;
/** Gets an indication of whether this message is being redelivered.
*
* <P>If a client receives a message with the <CODE>JMSRedelivered</CODE>
* field set,
* it is likely, but not guaranteed, that this message was delivered
* earlier but that its receipt was not acknowledged
* at that time.
*
* @return true if this message is being redelivered
*
* @exception JMSException if the JMS provider fails to get the redelivered
* state due to some internal error.
*
* @see javax.jms.Message#setJMSRedelivered(boolean)
*/
boolean
getJMSRedelivered() throws JMSException;
/** Specifies whether this message is being redelivered.
*
* <P>This field is set at the time the message is delivered. This
* method can be used to change the value for a message that has
* been received.
*
* @param redelivered an indication of whether this message is being
* redelivered
*
* @exception JMSException if the JMS provider fails to set the redelivered
* state due to some internal error.
*
* @see javax.jms.Message#getJMSRedelivered()
*/
void
setJMSRedelivered(boolean redelivered) throws JMSException;
/** Gets the message type identifier supplied by the client when the
* message was sent.
*
* @return the message type
*
* @exception JMSException if the JMS provider fails to get the message
* type due to some internal error.
*
* @see javax.jms.Message#setJMSType(String)
*/
String
getJMSType() throws JMSException;
/** Sets the message type.
*
* <P>Some JMS providers use a message repository that contains the
* definitions of messages sent by applications. The <CODE>JMSType</CODE>
* header field may reference a message's definition in the provider's
* repository.
*
* <P>The JMS API does not define a standard message definition repository,
* nor does it define a naming policy for the definitions it contains.
*
* <P>Some messaging systems require that a message type definition for
* each application message be created and that each message specify its
* type. In order to work with such JMS providers, JMS clients should
* assign a value to <CODE>JMSType</CODE>, whether the application makes
* use of it or not. This ensures that the field is properly set for those
* providers that require it.
*
* <P>To ensure portability, JMS clients should use symbolic values for
* <CODE>JMSType</CODE> that can be configured at installation time to the
* values defined in the current provider's message repository. If string
* literals are used, they may not be valid type names for some JMS
* providers.
*
* @param type the message type
*
* @exception JMSException if the JMS provider fails to set the message
* type due to some internal error.
*
* @see javax.jms.Message#getJMSType()
*/
void
setJMSType(String type) throws JMSException;
/** Gets the message's expiration value.
*
* <P>When a message is sent, the <CODE>JMSExpiration</CODE> header field
* is left unassigned. After completion of the <CODE>send</CODE> or
* <CODE>publish</CODE> method, it holds the expiration time of the
* message. This is the sum of the time-to-live value specified by the
* client and the GMT at the time of the <CODE>send</CODE> or
* <CODE>publish</CODE>.
*
* <P>If the time-to-live is specified as zero, <CODE>JMSExpiration</CODE>
* is set to zero to indicate that the message does not expire.
*
* <P>When a message's expiration time is reached, a provider should
* discard it. The JMS API does not define any form of notification of
* message expiration.
*
* <P>Clients should not receive messages that have expired; however,
* the JMS API does not guarantee that this will not happen.
*
* @return the time the message expires, which is the sum of the
* time-to-live value specified by the client and the GMT at the
* time of the send
*
* @exception JMSException if the JMS provider fails to get the message
* expiration due to some internal error.
*
* @see javax.jms.Message#setJMSExpiration(long)
*/
long
getJMSExpiration() throws JMSException;
/** Sets the message's expiration value.
*
* <P>JMS providers set this field when a message is sent. This method
* can be used to change the value for a message that has been received.
*
* @param expiration the message's expiration time
*
* @exception JMSException if the JMS provider fails to set the message
* expiration due to some internal error.
*
* @see javax.jms.Message#getJMSExpiration()
*/
void
setJMSExpiration(long expiration) throws JMSException;
/** Gets the message priority level.
*
* <P>The JMS API defines ten levels of priority value, with 0 as the
* lowest
* priority and 9 as the highest. In addition, clients should consider
* priorities 0-4 as gradations of normal priority and priorities 5-9
* as gradations of expedited priority.
*
* <P>The JMS API does not require that a provider strictly implement
* priority
* ordering of messages; however, it should do its best to deliver
* expedited messages ahead of normal messages.
*
* @return the default message priority
*
* @exception JMSException if the JMS provider fails to get the message
* priority due to some internal error.
*
* @see javax.jms.Message#setJMSPriority(int)
*/
int
getJMSPriority() throws JMSException;
/** Sets the priority level for this message.
*
* <P>JMS providers set this field when a message is sent. This method
* can be used to change the value for a message that has been received.
*
* @param priority the priority of this message
*
* @exception JMSException if the JMS provider fails to set the message
* priority due to some internal error.
*
* @see javax.jms.Message#getJMSPriority()
*/
void
setJMSPriority(int priority) throws JMSException;
/** Clears a message's properties.
*
* <P>The message's header fields and body are not cleared.
*
* @exception JMSException if the JMS provider fails to clear the message
* properties due to some internal error.
*/
void
clearProperties() throws JMSException;
/** Indicates whether a property value exists.
*
* @param name the name of the property to test
*
* @return true if the property exists
*
* @exception JMSException if the JMS provider fails to determine if the
* property exists due to some internal error.
*/
boolean
propertyExists(String name) throws JMSException;
/** Returns the value of the <CODE>boolean</CODE> property with the
* specified name.
*
* @param name the name of the <CODE>boolean</CODE> property
*
* @return the <CODE>boolean</CODE> property value for the specified name
*
* @exception JMSException if the JMS provider fails to get the property
* value due to some internal error.
* @exception MessageFormatException if this type conversion is invalid.
*/
boolean
getBooleanProperty(String name) throws JMSException;
/** Returns the value of the <CODE>byte</CODE> property with the specified
* name.
*
* @param name the name of the <CODE>byte</CODE> property
*
* @return the <CODE>byte</CODE> property value for the specified name
*
* @exception JMSException if the JMS provider fails to get the property
* value due to some internal error.
* @exception MessageFormatException if this type conversion is invalid.
*/
byte
getByteProperty(String name) throws JMSException;
/** Returns the value of the <CODE>short</CODE> property with the specified
* name.
*
* @param name the name of the <CODE>short</CODE> property
*
* @return the <CODE>short</CODE> property value for the specified name
*
* @exception JMSException if the JMS provider fails to get the property
* value due to some internal error.
* @exception MessageFormatException if this type conversion is invalid.
*/
short
getShortProperty(String name) throws JMSException;
/** Returns the value of the <CODE>int</CODE> property with the specified
* name.
*
* @param name the name of the <CODE>int</CODE> property
*
* @return the <CODE>int</CODE> property value for the specified name
*
* @exception JMSException if the JMS provider fails to get the property
* value due to some internal error.
* @exception MessageFormatException if this type conversion is invalid.
*/
int
getIntProperty(String name) throws JMSException;
/** Returns the value of the <CODE>long</CODE> property with the specified
* name.
*
* @param name the name of the <CODE>long</CODE> property
*
* @return the <CODE>long</CODE> property value for the specified name
*
* @exception JMSException if the JMS provider fails to get the property
* value due to some internal error.
* @exception MessageFormatException if this type conversion is invalid.
*/
long
getLongProperty(String name) throws JMSException;
/** Returns the value of the <CODE>float</CODE> property with the specified
* name.
*
* @param name the name of the <CODE>float</CODE> property
*
* @return the <CODE>float</CODE> property value for the specified name
*
* @exception JMSException if the JMS provider fails to get the property
* value due to some internal error.
* @exception MessageFormatException if this type conversion is invalid.
*/
float
getFloatProperty(String name) throws JMSException;
/** Returns the value of the <CODE>double</CODE> property with the specified
* name.
*
* @param name the name of the <CODE>double</CODE> property
*
* @return the <CODE>double</CODE> property value for the specified name
*
* @exception JMSException if the JMS provider fails to get the property
* value due to some internal error.
* @exception MessageFormatException if this type conversion is invalid.
*/
double
getDoubleProperty(String name) throws JMSException;
/** Returns the value of the <CODE>String</CODE> property with the specified
* name.
*
* @param name the name of the <CODE>String</CODE> property
*
* @return the <CODE>String</CODE> property value for the specified name;
* if there is no property by this name, a null value is returned
*
* @exception JMSException if the JMS provider fails to get the property
* value due to some internal error.
* @exception MessageFormatException if this type conversion is invalid.
*/
String
getStringProperty(String name) throws JMSException;
/** Returns the value of the Java object property with the specified name.
*
* <P>This method can be used to return, in objectified format,
* an object that has been stored as a property in the message with the
* equivalent <CODE>setObjectProperty</CODE> method call, or its equivalent
* primitive <CODE>set<I>type</I>Property</CODE> method.
*
* @param name the name of the Java object property
*
* @return the Java object property value with the specified name, in
* objectified format (for example, if the property was set as an
* <CODE>int</CODE>, an <CODE>Integer</CODE> is
* returned); if there is no property by this name, a null value
* is returned
*
* @exception JMSException if the JMS provider fails to get the property
* value due to some internal error.
*/
Object
getObjectProperty(String name) throws JMSException;
/** Returns an <CODE>Enumeration</CODE> of all the property names.
*
* <P>Note that JMS standard header fields are not considered
* properties and are not returned in this enumeration.
*
* @return an enumeration of all the names of property values
*
* @exception JMSException if the JMS provider fails to get the property
* names due to some internal error.
*/
Enumeration
getPropertyNames() throws JMSException;
/** Sets a <CODE>boolean</CODE> property value with the specified name into
* the message.
*
* @param name the name of the <CODE>boolean</CODE> property
* @param value the <CODE>boolean</CODE> property value to set
*
* @exception JMSException if the JMS provider fails to set the property
* due to some internal error.
* @exception IllegalArgumentException if the name is null or if the name is
* an empty string.
* @exception MessageNotWriteableException if properties are read-only
*/
void
setBooleanProperty(String name, boolean value)
throws JMSException;
/** Sets a <CODE>byte</CODE> property value with the specified name into
* the message.
*
* @param name the name of the <CODE>byte</CODE> property
* @param value the <CODE>byte</CODE> property value to set
*
* @exception JMSException if the JMS provider fails to set the property
* due to some internal error.
* @exception IllegalArgumentException if the name is null or if the name is
* an empty string.
* @exception MessageNotWriteableException if properties are read-only
*/
void
setByteProperty(String name, byte value)
throws JMSException;
/** Sets a <CODE>short</CODE> property value with the specified name into
* the message.
*
* @param name the name of the <CODE>short</CODE> property
* @param value the <CODE>short</CODE> property value to set
*
* @exception JMSException if the JMS provider fails to set the property
* due to some internal error.
* @exception IllegalArgumentException if the name is null or if the name is
* an empty string.
* @exception MessageNotWriteableException if properties are read-only
*/
void
setShortProperty(String name, short value)
throws JMSException;
/** Sets an <CODE>int</CODE> property value with the specified name into
* the message.
*
* @param name the name of the <CODE>int</CODE> property
* @param value the <CODE>int</CODE> property value to set
*
* @exception JMSException if the JMS provider fails to set the property
* due to some internal error.
* @exception IllegalArgumentException if the name is null or if the name is
* an empty string.
* @exception MessageNotWriteableException if properties are read-only
*/
void
setIntProperty(String name, int value)
throws JMSException;
/** Sets a <CODE>long</CODE> property value with the specified name into
* the message.
*
* @param name the name of the <CODE>long</CODE> property
* @param value the <CODE>long</CODE> property value to set
*
* @exception JMSException if the JMS provider fails to set the property
* due to some internal error.
* @exception IllegalArgumentException if the name is null or if the name is
* an empty string.
* @exception MessageNotWriteableException if properties are read-only
*/
void
setLongProperty(String name, long value)
throws JMSException;
/** Sets a <CODE>float</CODE> property value with the specified name into
* the message.
*
* @param name the name of the <CODE>float</CODE> property
* @param value the <CODE>float</CODE> property value to set
*
* @exception JMSException if the JMS provider fails to set the property
* due to some internal error.
* @exception IllegalArgumentException if the name is null or if the name is
* an empty string.
* @exception MessageNotWriteableException if properties are read-only
*/
void
setFloatProperty(String name, float value)
throws JMSException;
/** Sets a <CODE>double</CODE> property value with the specified name into
* the message.
*
* @param name the name of the <CODE>double</CODE> property
* @param value the <CODE>double</CODE> property value to set
*
* @exception JMSException if the JMS provider fails to set the property
* due to some internal error.
* @exception IllegalArgumentException if the name is null or if the name is
* an empty string.
* @exception MessageNotWriteableException if properties are read-only
*/
void
setDoubleProperty(String name, double value)
throws JMSException;
/** Sets a <CODE>String</CODE> property value with the specified name into
* the message.
*
* @param name the name of the <CODE>String</CODE> property
* @param value the <CODE>String</CODE> property value to set
*
* @exception JMSException if the JMS provider fails to set the property
* due to some internal error.
* @exception IllegalArgumentException if the name is null or if the name is
* an empty string.
* @exception MessageNotWriteableException if properties are read-only
*/
void
setStringProperty(String name, String value)
throws JMSException;
/** Sets a Java object property value with the specified name into the
* message.
*
* <P>Note that this method works only for the objectified primitive
* object types (<CODE>Integer</CODE>, <CODE>Double</CODE>,
* <CODE>Long</CODE> ...) and <CODE>String</CODE> objects.
*
* @param name the name of the Java object property
* @param value the Java object property value to set
*
* @exception JMSException if the JMS provider fails to set the property
* due to some internal error.
* @exception IllegalArgumentException if the name is null or if the name is
* an empty string.
* @exception MessageFormatException if the object is invalid
* @exception MessageNotWriteableException if properties are read-only
*/
void
setObjectProperty(String name, Object value)
throws JMSException;
/** Acknowledges all consumed messages of the session of this consumed
* message.
*
* <P>All consumed JMS messages support the <CODE>acknowledge</CODE>
* method for use when a client has specified that its JMS session's
* consumed messages are to be explicitly acknowledged. By invoking
* <CODE>acknowledge</CODE> on a consumed message, a client acknowledges
* all messages consumed by the session that the message was delivered to.
*
* <P>Calls to <CODE>acknowledge</CODE> are ignored for both transacted
* sessions and sessions specified to use implicit acknowledgement modes.
*
* <P>A client may individually acknowledge each message as it is consumed,
* or it may choose to acknowledge messages as an application-defined group
* (which is done by calling acknowledge on the last received message of the group,
* thereby acknowledging all messages consumed by the session.)
*
* <P>Messages that have been received but not acknowledged may be
* redelivered.
*
* @exception JMSException if the JMS provider fails to acknowledge the
* messages due to some internal error.
* @exception IllegalStateException if this method is called on a closed
* session.
*
* @see javax.jms.Session#CLIENT_ACKNOWLEDGE
*/
void
acknowledge() throws JMSException;
/** Clears out the message body. Clearing a message's body does not clear
* its header values or property entries.
*
* <P>If this message body was read-only, calling this method leaves
* the message body in the same state as an empty body in a newly
* created message.
*
* @exception JMSException if the JMS provider fails to clear the message
* body due to some internal error.
*/
void
clearBody() throws JMSException;
}