progress.message.jclient
Interface Message

All Superinterfaces:

Message

All Known Subinterfaces:

BytesMessage, MapMessage, MultipartMessage, ObjectMessage, StreamMessage, TextMessage, XMLMessage

public interface Message
extends Message

An Implementation of JMS Message. The Message interface is the root interface of all JMS messages. It defines the JMS header and the acknowledge method used for all messages.

Most 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.

Within this general form, the definition of a message varies significantly across products. It would be quite difficult for JMS to support all of these message models.

With this in mind, the JMS message model has the following goals:

• Provide a single, unified message API
• Provide an API suitable for creating messages that match the format used by existing non-JMS applications
• Support the development of hetrogeneous applications that span operating systems, machine architectures and computer languages
• Support messages containing Java objects
• Support messages containing Extensible Markup Language (XML) pages

JMS Messages are composed of the following parts:

• 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.
• 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.
• Body - JMS defines several types of message body which cover the majority of messaging styles currently in use.

JMS defines five types of message body:

• Stream - a stream of Java primitive values. It is filled and read sequentially.
• Map - a set of name-value pairs where names are Strings and values are Java primitive types. The entries can be accessed sequentially or randomly by name. The order of the entries is undefined.
• Text - a message containing a java.util.StringBuffer. The inclusion of this message type is based on our presumption that XML will likely become a popular mechanism for representing content of all kinds including the content of JMS messages.
• Object - a message that contains a Serializable java object
• Bytes - a stream of uninterpreted bytes. This message type is for literally encoding a body to match an existing message format. In many cases, it will be possible to use one of the other, easier to use, body types instead. Although JMS allows the use of message properties with byte messages it is typically not done since the inclusion of properties may affect the format.

The JMSCorrelationID header field is used for linking one message with another. It typically links a reply message with its requesting message.

JMSCorrelationID can hold either a provider-specific message ID, an application-specific String or a provider-native byte[] value.

A Message 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.

Properties allow an application, via message selectors, to have a JMS provider select/filter messages on its behalf using application-specific criteria.

Property names must obey the rules for a message selector identifier.

Property values can be boolean, byte, short, int, long, float, double, and String.

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 MessageNotWriteableException is thrown. If clearProperties is called, the properties can now be both read from and written to.

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 only use message properties when they need to customize a message's header. The primary reason for doing this is to support customized message selection.

Message properties support the following conversion table. The marked cases must be supported. The unmarked cases must throw a JMSException. The String to primitive conversions may throw a runtime exception if the primitives valueOf() method does not accept it as a valid String representation of the primitive.

A value written as the row type can be read as the column type.

 |        | 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
 |----------------------------------------------------------
 

In addition to the type-specific set/get methods for properties, JMS provides the setObjectProperty and getObjectProperty 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.

The setObjectProperty method accepts values of class Boolean, Byte, Short, Integer, Long, Float, Double and String. An attempt to use any other class must throw a JMSException.

The getObjectProperty method only returns values of class Boolean, Byte, Short, Integer, Long, Float, Double and String.

The order of property values is not defined. To iterate through a message's property values, use getPropertyNames to retrieve a property name enumeration and then use the various property get methods to retrieve their values.

A message's properties are deleted by the clearProperties method. This leaves the message with an empty set of properties.

Getting a property value for a name which has not been set returns a null value. Only the getStringProperty and getObjectProperty methods can return a null value. The other property get methods must throw a java.lang.NullPointerException if they are used to get a non-existent property.

JMS reserves the `JMSX' 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 JMS. Support for these properties is optional. The String[] ConnectionMetaData.getJMSXPropertyNames method returns the names of the JMSX properties supported by a connection.

JMSX properties may be referenced in message selectors whether or not they are supported by a connection. They are treated like any other absent property.

JSMX properties `set by provider on send' are available to both the producer and the consumers of the message. JSMX properties `set by provider on receive' are only available to the consumers.

JMSXGroupID and JMSXGroupSeq are simply standard properties 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.

JMS reserves the `JMS_' property name prefix for provider-specific properties. Each provider defines there own value of . This is the mechanism a JMS provider uses to make its special per message services available to a JMS client.

The purpose of provider-specific properties is to provide special features needed to support JMS use with provider-native clients. They should not be used for JMS to JMS messaging.

JMS provides a set of message interfaces that define the JMS message model. It does not provide implementations of these interfaces.

Each JMS provider supplies a set of message factories with its Session object for creating instances of these messages. This allows a provider to use implementations tailored to their specific needs.

A provider must be prepared to accept message implementations that are not its own. They may not be handled as efficiently as their own implementations; however, they must be handled.

A JMS message selector allows a client to specify by message header the messages it's interested in. Only messages whose headers match the selector are delivered. The semantics of not delivered differ a bit depending on the MessageConsumer being used (see QueueReceiver and TopicSubscriber).

Message selectors cannot reference message body values.

A message selector matches a message when the selector evaluates to true when the message's header field and property values are substituted for their corresponding identifiers in the selector.

A message selector is a String, whose syntax is based on a subset of the SQL92 conditional expression syntax.

The order of evaluation of a message selector is from left to right within precedence level. Parenthesis can be used to change this order.

Predefined selector literals and operator names are written here in upper case; however, they are case insensitive.

A selector can contain:

• Literals:
  • A string literal is enclosed in single quotes with single quote represented by doubled single quote such as `literal' and `literal''s'; like Java string literals these use the unicode character encoding.
  • An exact numeric literal is a numeric value without a decimal point such as 57, -957, +62; numbers in the range of Java long are supported.
  • An approximate numeric literal is a numeric value in scientific notation such as 7E3, -57.9E2 or a numeric value with a decimal such as 7., -95.7, +6.2; numbers in the range of Java double are supported.
  • The boolean literals TRUE, true, FALSE and false.
• Identifiers:
  • An identifier is an unlimited length sequence of Java letters and Java digits, the first of which must be a Java letter. A letter is any character for which the method Character.isJavaLetter returns true. This includes `_' and `$'. A letter or digit is any character for which the method Character.isJavaLetterOrDigit returns true.
  • Identifiers cannot be the names NULL, TRUE, or FALSE.
  • Identifiers cannot be NOT, AND, OR, BETWEEN, LIKE, IN, and IS.
  • Identifiers are either header field references or property references.
  • Identifiers are case sensitive.
  • Message header field references are restricted to JMSDeliveryMode, JMSPriority, JMSMessageID, JMSTimestamp, JMSCorrelationID, and JMSType. JMSMessageID, JMSTimestamp, JMSCorrelationID, and JMSType values may be null and if so are treated as a NULL value.
  • Any name beginning with `JMSX' is a JMS defined property name.
  • Any name beginning with `JMS_' is a provider-specific property name.
  • Any name that does not begin with `JMS' is an application-specific property name. If a property is referenced that does not exist in a message its value is NULL. If it does exist, its value is the corresponding property value.
• Whitespace is the same as that defined for Java: space, horizontal tab, form feed and line terminator.
• Expressions:
  • A selector is a conditional expression; a selector that evaluates to true matches; a selector that evaluates to false or unknown does not match.
  • Arithmetic expressions are composed of themselves, arithmetic operations, identifiers (whose value is treated as a numeric literal) and numeric literals.
  • Conditional expressions are composed of themselves, comparison operations and logical operations.
• Standard bracketing () for ordering expression evaluation is supported.
• Logical operators in precedence order: NOT, AND, OR
• Comparison operators: =, >, >=, <, <=, <> (not equal)
  • Only like type values can be compared. An exact numeric value can only be compared with an exact numeric value. The same type correspondence restriction applies to comparison of approximate numeric, String and boolean values. If the comparison of non-like type values is attempted, the selector is always false.
  • String comparison is restricted to = and <>. Two strings are equal if and only if they contain the same sequence of characters.
• Arithmetic operators in precedence order:
  • +, - unary
  • *, / multiplication and division
  • +, - addition and subtraction
  • Arithmetic operations on a NULL value are not supported; if they are attempted, the complete selector is always false.
  • Arithmetic operations must use Java numeric promotion.
• arithmetic-expr1 [NOT] BETWEEN arithmetic-expr2 and arithmetic-expr3 comparison operator
  • age BETWEEN 15 and 19 is equivalent to age >= 15 AND age <= 19
  • age NOT BETWEEN 15 and 19 is equivalent to age < 15 OR age > 19
  • If any of the exprs of a BETWEEN operation are NULL the value of the operation is false; if any of the exprs of a NOT BETWEEN operation are NULL the value of the operation is true.
• identifier [NOT] IN (string-literal1, string-literal2,...) comparison operator where identifer has a String or NULL value.
  • Country IN (' UK', 'US', 'France') is true for `UK' and false for `Peru' it is equivalent to the expression (Country = ' UK') OR (Country = ' US') OR (Country = ' France')
  • Country NOT IN (' UK', 'US', 'France') is false for `UK' and true for `Peru' it is equivalent to the expression NOT ((Country = ' UK') OR (Country = ' US') OR (Country = ' France'))
  • If identifier of an IN or NOT IN operation is NULL the value of the operation is unknown.
• identifier [NOT] LIKE pattern-value [ESCAPE escape-character] comparison operator, where identifier has a String value; pattern-value is a string literal where `_' stands for any single character; `%' stands for any sequence of characters (including the empty sequence); and all other characters stand for themselves. The optional escape-character is a single character string literal whose character is used to escape the special meaning of the `_' and `%' in pattern-value.
  • phone LIKE `12%3' is true for `123' `12993' and false for `1234'
  • word LIKE `l_se' is true for `lose' and false for `loose'
  • underscored LIKE `\_%' ESCAPE `\' is true for `_foo' and false for `bar'
  • phone NOT LIKE `12%3' is false for `123' `12993' and true for `1234'
  • If identifier of a LIKE or NOT LIKE operation is NULL the value of the operation is unknown.
• identifier IS NULL comparison operator tests for a null header field value, or a missing property value.
  • prop_name IS NULL
• identifier IS NOT NULL comparison operator tests for the existence of a non null header field value or a property value.
  • prop_name IS NOT NULL

  JMS providers are required to verify the syntactic correctness of a message selector at the time it is presented. A method providing a syntactically incorrect selector must result in a JMSException.

  The following message selector selects messages with a message type of car and color of blue and weight greater than 2500 lbs:

  "JMSType = `car' AND color = `blue' AND weight > 2500"

  As noted above, property values may be NULL. The evaluation of selector expressions containing NULL values is defined by SQL 92 NULL semantics. A brief description of these semantics is provided here.

  SQL treats a NULL value as unknown. Comparison or arithmetic with an unknown value always yields an unknown value.

  The IS NULL and IS NOT NULL operators convert an unknown value into the respective TRUE and FALSE values.

  The boolean operators use three valued logic as defined by the following tables:

  The definition of the AND operator

   | AND  |   T   |   F   |   U
   +------+-------+-------+-------
   |  T   |   T   |   F   |   U
   |  F   |   F   |   F   |   F
   |  U   |   U   |   F   |   U
   +------+-------+-------+-------
   

  The definition of the OR operator

   | OR   |   T   |   F   |   U
   +------+-------+-------+--------
   |  T   |   T   |   T   |   T
   |  F   |   T   |   F   |   U
   |  U   |   T   |   U   |   U
   +------+-------+-------+-------
   

  The definition of the NOT operator

   | NOT
   +------+------
   |  T   |   F
   |  F   |   T
   |  U   |   U
   +------+-------
   

  When used in a message selector JMSDeliveryMode is treated as having the values `PERSISTENT' and `NON_PERSISTENT'.

  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 an approximate numeric values).

  SQL comments are not supported.

  Version:

  1.0 - December 1998

  Author:

  Bill Collins

  See Also:

  Message, BytesMessage, MapMessage, ObjectMessage, StreamMessage, TextMessage

  Field Summary

  Fields inherited from interface javax.jms.Message

  DEFAULT_DELIVERY_MODE, DEFAULT_PRIORITY, DEFAULT_TIME_TO_LIVE

  Method Summary

  void	acknowledgeAndForward(Destination destination) A SonicMQ extension - acknowledge this message and forward it to a new destination.
  void	acknowledgeAndForward(Destination destination, int deliveryMode, int priority, long timeToLive) A SonicMQ extension - acknowledge this message and forward it to a new destination.
  int	getBodySize() Return the size of the Message body.
  Channel	getChannel() Retrieve the channel attached to this message.
  Destination	getDestinationProperty(java.lang.String name) Return the value of the javax.jms.Destination property with the specified name.
  java.util.Hashtable	getProperties() Get message properties.
  boolean	hasChannel() Return true if this message has a channel attached.
  boolean	isDestinationProperty(java.lang.String name) Indicates whether a property is a javax.jms.Destination property.
  void	setChannel(Channel channel) Add the given channel to the message.
  void	setChannel(Message message) Add the channel associated with the given message to this channel.
  void	setDestinationProperty(java.lang.String name, Destination value) Set a javax.jms.Destination property value with the specified name into the Message.

  Methods inherited from interface javax.jms.Message

  acknowledge, clearBody, clearProperties, getBooleanProperty, getByteProperty, getDoubleProperty, getFloatProperty, getIntProperty, getJMSCorrelationID, getJMSCorrelationIDAsBytes, getJMSDeliveryMode, getJMSDestination, getJMSExpiration, getJMSMessageID, getJMSPriority, getJMSRedelivered, getJMSReplyTo, getJMSTimestamp, getJMSType, getLongProperty, getObjectProperty, getPropertyNames, getShortProperty, getStringProperty, propertyExists, setBooleanProperty, setByteProperty, setDoubleProperty, setFloatProperty, setIntProperty, setJMSCorrelationID, setJMSCorrelationIDAsBytes, setJMSDeliveryMode, setJMSDestination, setJMSExpiration, setJMSMessageID, setJMSPriority, setJMSRedelivered, setJMSReplyTo, setJMSTimestamp, setJMSType, setLongProperty, setObjectProperty, setShortProperty, setStringProperty

  Method Detail

  acknowledgeAndForward

  void acknowledgeAndForward(Destination destination,
                             int deliveryMode,
                             int priority,
                             long timeToLive)
                             throws JMSException

  A SonicMQ extension - acknowledge this message and forward it to a new destination.

  This method can be called only on messages that were received in a progress.message.jclient.Session.SINGLE_MESSAGE_ACKNOWLEDGE session. The acknowledgment and the move to the new destination are performed as an atomic operation - SonicMQ guarantees that either both succeed or both fail. Other messages that might have been received before this message, through the same session, are not affected. acknowledgeAndForward can be only if the message was not yet acknowledged.

  acknowledgeAndForward should be used for better performance - similar functionality can be achieved by acknowledging the message and then sending it to the new destination in a transacted session - but acknowledgeAndForward is more efficient.

  acknowledgeAndForward is currently supported only by messages that were received from a queue destination and are forwarded to a queue.

  Parameters:

  destination - The new destination (queue only) of this message.

  deliveryMode - the delivery mode to use.

  priority - the priority for this message.

  timeToLive - the message's lifetime (in milliseconds).

  Throws:

  InvalidDestinationException - if this destination is not a valid queue.

  JMSSecurityException - if this client doesn't have permission to send to the new queue destination.

  java.lang.IllegalStateException - if this message was not received through a SINGLE_MESSAGE_ACKNOWLEDGE session or was already acknowledged.

  JMSException - if JMS fails to acknowledge and forward the message due to some internal error.

  acknowledgeAndForward

  void acknowledgeAndForward(Destination destination)
                             throws JMSException

  A SonicMQ extension - acknowledge this message and forward it to a new destination.

  This method can be called only on messages that were received in a progress.message.jclient.Session.SINGLE_MESSAGE_ACKNOWLEDGE session. The acknowledgment and the move to the new destination are performed as an atomic operation - SonicMQ guarantees that either both succeed or both fail. Other messages that might have been received before this message, through the same session, are not affected. acknowledgeAndForward can be only if the message was not yet acknowledged.

  acknowledgeAndForward should be used for better performance - similar functionality can be achieved by acknowledging the message and then sending it to the new destination in a transacted session - but acknowledgeAndForward is more efficient.

  acknowledgeAndForward is currently supported only by messages that were received from a queue destination and are forwarded to a queue.

  The delivery parameters - JMSDeliveryMode, JMSPriority and JMSTimeToLive of this message are used by default for forwarding it to the new destination.

  Parameters:

  destination - The new destination (queue only) of this message.

  Throws:

  InvalidDestinationException - if this destination is not a valid queue.

  JMSSecurityException - if this client doesn't have permission to send to the new queue destination.

  java.lang.IllegalStateException - if this message was not received through a SINGLE_MESSAGE_ACKNOWLEDGE session or was already acknowledged.

  JMSException - if JMS fails to acknowledge and forward the message due to some internal error.

  getChannel

  Channel getChannel()
                     throws JMSException

  Retrieve the channel attached to this message.

  Throws:

  JMSException

  setChannel

  void setChannel(Channel channel)
                  throws JMSException

  Add the given channel to the message.

  Throws:

  JMSException

  setChannel

  void setChannel(Message message)
                  throws JMSException

  Add the channel associated with the given message to this channel.

  You will receive an javax.jms.IllegalStateException if you attempt to set a channel on a message that already has a channel, you attempt to set an active channel onto another message, or the message does not already have a channel.

  This method is useful if you wish to forward a message with a channel to another location using a different message other than the one you received it on.

  Parameters:

  message - The Message to retrieve the channel from.

  Throws:

  JMSException - If there is an internal JMS error.

  hasChannel

  boolean hasChannel()
                     throws JMSException

  Return true if this message has a channel attached.

  Throws:

  JMSException

  getBodySize

  int getBodySize()
                  throws JMSException

  Return the size of the Message body.

  Returns:

  The size of the message body in bytes.

  Throws:

  JMSException

  getProperties

  java.util.Hashtable getProperties()

  Get message properties.

  Returns:

  the message properties.

  isDestinationProperty

  boolean isDestinationProperty(java.lang.String name)

  Indicates whether a property is a javax.jms.Destination property.

  Parameters:

  name - the name of the property to test

  Returns:

  true if a property with the specified name exists and the type of the property is javax.jms.Destination; otherwise, this method returns false

  getDestinationProperty

  Destination getDestinationProperty(java.lang.String name)
                                     throws JMSException

  Return the value of the javax.jms.Destination property with the specified name.

  Parameters:

  name - the name of the Destination property

  Returns:

  the javax.jms.Destination property value with the given name.

  Throws:

  JMSException - if JMS fails to get Property due to some internal JMS error.

  MessageFormatException - if this type conversion is invalid.

  setDestinationProperty

  void setDestinationProperty(java.lang.String name,
                              Destination value)
                              throws JMSException

  Set a javax.jms.Destination property value with the specified name into the Message.

  Parameters:

  name - the name of the javax.jms.Destination property

  value - the javax.jms.Destination property value to set in the Message.

  Throws:

  JMSException - if JMS fails to set Property due to some internal JMS error.

  MessageNotWriteableException - if properties are read-only