MESSAGE ORIENTED MODEL (MOM). Slide 2CITE 4420 Message Oriented Model Message-Oriented Model (MOM)

MESSAGE ORIENTED MESSAGE ORIENTED MODEL (MOM)MODEL (MOM)

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Message-Oriented Model (MOM)Message-Oriented Model (MOM)

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Elements of the MOMElements of the MOM

• Correlation• Intermediary• Message• Message envelope• Message exchange pattern• Message header

• Correlation• Intermediary• Message• Message envelope• Message exchange pattern• Message header

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Elements of MOM (Cont’d)Elements of MOM (Cont’d)

• Message description language

• Message identifier

• Message path

• Message recipient

• Message sender

• Message description language

• Message identifier

• Message path

• Message recipient

• Message sender

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Elements of MOM (Cont’d)Elements of MOM (Cont’d)

• Message transport

• Reliable messaging

• Message transport

• Reliable messaging

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CorrelationCorrelation

• A means of associating a message with a context

– The message received is the one expected by this message recipient

Usually accomplished with a message identifier

• A means of associating a message with a context

– The message received is the one expected by this message recipient

Usually accomplished with a message identifier

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IntermediaryIntermediary

• An agent that is both a message recipient and a message sender

• May have partial access to the message it processes

• Forwards the message along the message path

• An agent that is both a message recipient and a message sender

• May have partial access to the message it processes

• Forwards the message along the message path

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MessageMessage

• A unit of data sent from one agent to another

• May be part of a message exchange pattern

• Described by a message description language

• A unit of data sent from one agent to another

• May be part of a message exchange pattern

• Described by a message description language

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Message (Cont’d)Message (Cont’d)

• Has a message sender

• Has a message identifier

• May have a message content

• Has zero or more message headers

• May have a message envelope

• Has a message sender

• Has a message identifier

• May have a message content

• Has zero or more message headers

• May have a message envelope

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Message EnvelopeMessage Envelope

• Is meta-data associated with a message

• Contains address information about intended recipients

• Contains the body of the message

• Is meta-data associated with a message

• Contains address information about intended recipients

• Contains the body of the message

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Message Exchange Pattern (MEP)Message Exchange Pattern (MEP)

• A template describing a generic pattern for the exchange of messages between agents

• A feature of the architecture• Should have a unique identifier• Is the life cycle of a message exchange

• A template describing a generic pattern for the exchange of messages between agents

• A feature of the architecture• Should have a unique identifier• Is the life cycle of a message exchange

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MEP (Cont’d)MEP (Cont’d)

• Describes the temporal and causal relationships, if any, of multiple messages exchanged in conformance with the pattern

• Describes the normal and abnormal termination of any message exchange conforming to the pattern

• Realizes the message correlation• Describes a service invocation• Must be mapped to a protocol

• Describes the temporal and causal relationships, if any, of multiple messages exchanged in conformance with the pattern

• Describes the normal and abnormal termination of any message exchange conforming to the pattern

• Realizes the message correlation• Describes a service invocation• Must be mapped to a protocol

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Message HeaderMessage Header

• Is part of a message• May contain routing information• May contain message security info• May contain message orchestration

information• May contain message transaction context

• Is part of a message• May contain routing information• May contain message security info• May contain message orchestration

information• May contain message transaction context

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Message OrchestrationMessage Orchestration

• Encapsulates and executes business process logic

• Can integrate with other applications to retrieve additional data

• Can invoke broker component• Can use application logic• Can reject data that fails validation

• Encapsulates and executes business process logic

• Can integrate with other applications to retrieve additional data

• Can invoke broker component• Can use application logic• Can reject data that fails validation

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Message Description LanguageMessage Description Language

• Describes the structure of the message

– Types of the elements– How recipients and senders are identified– Which headers are associated with the

message

• Describes the structure of the message

– Types of the elements– How recipients and senders are identified– Which headers are associated with the

message

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Message IdentifierMessage Identifier

• A field that uniquely identifies a message• Allows messages to be correlated within an

extended transaction• Supports message reliability• Supports message management and

accountability of services

• A field that uniquely identifies a message• Allows messages to be correlated within an

extended transaction• Supports message reliability• Supports message management and

accountability of services

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Message PathMessage Path

• Is a sequence of agents

• Contains zero or more intermediaries

• Has a unique originator and recipient

• Message may be processed by a number of interdediaries

• Is a sequence of agents

• Contains zero or more intermediaries

• Has a unique originator and recipient

• Message may be processed by a number of interdediaries

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Message RecipientMessage Recipient

• A agent that receives a message

• May be an intermediary

• Has an agent identifier

• Agent identifier is not used for broadcast messages

• A agent that receives a message

• May be an intermediary

• Has an agent identifier

• Agent identifier is not used for broadcast messages

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Message SenderMessage Sender

• The agent that transmits a message• Sender may be an intermediary• May be identified by its agent identifier

in the message envelope• Identifier not present in anonymous

interactions

• The agent that transmits a message• Sender may be an intermediary• May be identified by its agent identifier

in the message envelope• Identifier not present in anonymous

interactions

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Message TransportMessage Transport

• A mechanism that may be used by agents to deliver a message

• Examples:– HTTP over TCP– SOAP transport– Message-oriented middleware

• A mechanism that may be used by agents to deliver a message

• Examples:– HTTP over TCP– SOAP transport– Message-oriented middleware

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Message Transport (Cont’d)Message Transport (Cont’d)

• Responsibilities:– Timeliness of transport– Privacy– Reliability

• Responsibilities:– Timeliness of transport– Privacy– Reliability

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Reliable MessagingReliable Messaging

• A key infrastructure-level component of reliability

• Realized by a combination of message acknowledgement and correlation

• A key infrastructure-level component of reliability

• Realized by a combination of message acknowledgement and correlation