Enterprise Integration PatternsMessaging Patterns

Process ManagerProcess Manager

Messaging Patterns

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The Routing Slip demonstrates how a message can be routed through a dynamic series of processing steps. The solution of the Routing Slip is based on two key assumptions: the sequence of processing steps has to be determined up-front and the sequence is linear. In many cases, these assumptions may not be fulfilled. For example, routing decisions might have to be made based on intermediate results. Or, the processing steps may not be sequential, but multiple steps might be executed in parallel.

How do we route a message through multiple processing steps when the required steps may not be known at design-time and may not be sequential?

Use a central processing unit, a Process Manager, to maintain the state of the sequence and determine the next processing step based on intermediate results.

First of all, let me clarify that the design and configuration of a Process Manager is a pretty extensive topic. We could probably fill a whole book (Volume 2, maybe?) with patterns related to the design of workflow or business process management. Therefore, this pattern is intended primarily to "round off" the topic of routing patterns and to provide a pointer into the direction of workflow and process modeling. By no means is it a comprehensive treatment of business process design.


Related patterns: Aggregator, Asynchronous Implementation with MSMQ, Asynchronous Implementation with TIBCO ActiveEnterprise, Content-Based Router, Correlation Identifier, Emerging Standards and Futures in Enterprise Integration, Message Channel, Message History, Message Store, Message Translator, Pipes and Filters, Publish-Subscribe Channel, Routing Slip, Claim Check

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Enterprise Integration Patterns Find the full description of this pattern in:
Enterprise Integration Patterns
Gregor Hohpe and Bobby Woolf
ISBN 0321200683
650 pages
Creative Commons Attribution License Parts of this page are made 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.

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