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DetourDetour

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A Wire Tap is useful to inspect messages that travel across a channel. Sometimes, though, we need to modify or reroute the messages instead of simply inspecting them.

How can you route a message through intermediate steps to perform validation, testing or debugging functions?

Construct a Detour with a context-based router controlled via the Control Bus. In one state the router routes incoming messages through additional steps while in the other it routes messages directly to the destination channel.

The Detour uses a simple context-based router with two output channels. One output channel passes the unmodified message to the original destination. When instructed by the Control Bus, the Detour routes messages to a different channel. This channel sends the message to additional components that can inspect and/or modify the message. Ultimately, these components route the message to the same destination.

...

Related patterns: Control Bus, Publish-Subscribe Channel, Wire Tap


Enterprise Integration Patterns Find the full description of this pattern in:
Enterprise Integration Patterns
Gregor Hohpe and Bobby Woolf
ISBN 0321200683
650 pages
Addison-Wesley
Creative Commons License Parts of this page are available under the Creative Commons Attribution license. You can reuse the pattern icon, the pattern name, the problem and solution statements (in bold), and the sketch under this license. Other portions of the text, such as text chapters or the full pattern text, are protected by copyright.

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Table of Contents
Revision History
Preface
Introduction
Solving Integration Problems using Patterns
Integration Styles
File Transfer
Shared Database
Remote Procedure Invocation
Messaging
Messaging Systems
Message Channel
Message
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
Request-Reply
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
Splitter
Aggregator
Resequencer
Composed Msg. Processor
Scatter-Gather
Routing Slip
Process Manager
Message Broker
Message Transformation
Envelope Wrapper
Content Enricher
Content Filter
Claim Check
Normalizer
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
Detour
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
Appendices
Bibliography