Enterprise Integration Patterns
Messaging Patterns
Smart ProxySmart ProxyMessaging Patterns » System Management

A pair of Wire Taps can be used to track messages that flow through a component. However, this approach assumes that the component publishes messages to a fixed output channel. However, many service-style components publish reply messages to the channel specified by the Return Address included in the request message.

How can you track messages on a service that publishes reply messages to the Return Address specified by the requestor?

Use a Smart Proxy to store the Return Address supplied by the original requestor and replace it with the address of the Smart Proxy. When the service sends the reply message route it to the original Return Address.

The Smart Proxy intercepts messages sent on the request channel to the Request-Reply service. For each incoming message, the Smart Proxy stores the Return Address specified by the original sender. It then replaces the Return Address in the message with the channel the reply channel that the Smart Proxy is listening on. When a reply message comes in on that channel, the Smart Proxy retrieves the stored Return Address and uses a Message Router to forward the unmodified reply address to that channel.


Related patterns: Correlation Identifier, Message Router, Request-Reply, Return Address, Wire Tap

Table of Contents
Solving Integration Problems using Patterns
Integration Styles
File Transfer
Shared Database
Remote Procedure Invocation
Messaging Systems
Message Channel
Pipes and Filters
Message Router
Message Translator
Message Endpoint
Messaging Channels
Point-to-Point Channel
Publish-Subscribe Channel
Datatype Channel
Invalid Message Channel
Dead Letter Channel
Guaranteed Delivery
Channel Adapter
Messaging Bridge
Message Bus
Message Construction
Command Message
Document Message
Event Message
Return Address
Correlation Identifier
Message Sequence
Message Expiration
Format Indicator
Interlude: Simple Messaging
JMS Request/Reply Example
.NET Request/Reply Example
JMS Publish/Subscribe Example
Message Routing
Content-Based Router
Message Filter
Dynamic Router
Recipient List
Composed Msg. Processor
Routing Slip
Process Manager
Message Broker
Message Transformation
Envelope Wrapper
Content Enricher
Content Filter
Claim Check
Canonical Data Model
Interlude: Composed Messaging
Synchronous (Web Services)
Asynchronous (MSMQ)
Asynchronous (TIBCO)
Messaging Endpoints
Messaging Gateway
Messaging Mapper
Transactional Client
Polling Consumer
Event-Driven Consumer
Competing Consumers
Message Dispatcher
Selective Consumer
Durable Subscriber
Idempotent Receiver
Service Activator
System Management
Control Bus
Wire Tap
Message History
Message Store
Smart Proxy
Test Message
Channel Purger
Interlude: Systems Management Example
Instrumenting Loan Broker
Integration Patterns in Practice
Case Study: Bond Trading System
Concluding Remarks
Emerging Standards
Revision History

Enterprise Integration Patterns

Find the full description of this pattern in:
Enterprise Integration Patterns
Gregor Hohpe and Bobby Woolf
ISBN 0321200683
650 pages

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