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My ongoing thoughts about the present and future of integration, SOA and Web services. [see all]
Reflecting on Enterprise Integration Patterns
(January 1, 2008)
Google Gears Live From Japan
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Popular Articles
SOA Patterns - New Insights or Recycled Knowledge?
Let's Have a Conversation
(IEEE Internet Computing)
Programming Without a Call Stack - Event-driven Architectures
(ObjektSpektrum, 2006)

Your Coffee Shop Does Not Use Two-Phase Commit
(IEEE Software Magazine)

Developing in a Service-Oriented World
(Whitepaper)

Integration Patterns with BizTalk Server 2004
(Whitepaper)
An Asynchronous World
(Software Development Magazine, July 2003)
Test-Driven Development in Integration Projects
(Whitepaper)

XML Abuse
(Software Development Magazine, Dec 2002)

 
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Video of Conversations Between Loosely Coupled Services on infoQ.
Video of Developing in a Service-oriented World now available on infoQ.
Guest article on conversations published in IEEE Internet Computing.
"Starbucks Does Not Use Two-Phase Commit" selected for "The Best Software Writing"
 
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Developing in a Service-Oriented World

Programming without a Call Stack: Event-driven Architectures

Software Visualization and Model Extraction

Conversations Between Loosely Coupled Systems

Enterprise Integration Patterns

Patterns Roundtable
MSDN TV
Roundtable on .NET Patterns

 

 
 
 

Patterns and Best Practices for Enterprise Integration

This site is dedicated to making the design and implementation of integration solutions easier. The solutions and approaches described here are relevant for integration tools and platforms such as IBM WebSphere MQ, TIBCO, Vitria, SeeBeyond, WebMethods, BizTalk, JMS,WCF, MSMQ, ESB's such as Sonic, Fiorano, ServiceMix, or Mule, plus SOA and Web-service based solutions.

All content on this site is original and is maintained by Gregor Hohpe. I have been building integration solutions for large clients for many years and enjoy sharing my findings with the community. I hope you find this material insightful and useful. Please contact me if you have suggestions or feedback.

Enterprise Integration Patterns - The Book

Enterprise integration remains harder than it really should be. While integration is inherently complex I felt that one of the major stumbling blocks is the lack of a common vocabulary and body of knowledge around asynchronous messaging architectures used to build integration solutions. Under the guidance of Martin Fowler and Kyle Brown, I teamed up with Bobby Woolf to create such a language in the form of 65 integration patterns (see the links on the right)

The book Enterprise Integration Patterns provides a consistent vocabulary and visual notation framework to describe large-scale integration solutions across many technologies. It also explores in detail the advantages and limitations of asynchronous messaging architectures. You will learn how to design code that connects an application to a messaging system, how to route messages to the proper destination and how to monitor the health of a messaging system. The patterns in the book are technology-agnostic and come to life with examples implemented in different messaging technologies, such as SOAP, JMS, MSMQ, .NET, TIBCO and other EAI Tools. Download a sample chapter!

"If you are involved with the operation or development of an enterprise application, there will doubtless come a time when you will need to integrate your application with another using the emerging preferred approach of messaging. When that time comes, this book will be your most valuable reference."
--Randy Stafford, Oracle [More Testimonials]

Why Do We Need Integration?

Today's business applications rarely live in isolation. Users expect instant access to all business functions an enterprise can offer, regardless of which system the functionality may reside in. This requires disparate applications to be connected into a larger, integrated solution. This integration is usually achieved through the use of some form of "middleware". Middleware provides the "plumbing" such as data transport, data transformation, and routing.

What Makes Integration so Hard?

Architecting integration solutions is a complex task. There are many conflicting drivers and even more possible 'right' solutions. Whether the architecture was in fact a good choice usually is not known until many months or even years later, when inevitable changes and additions put the original architecture to test. Unfortunately, there is no "cookbook" for enterprise integration solutions. Most integration vendors provide methodologies and best practices, but these instructions tend to be very much geared towards the vendor-provided tool set and often lack treatment of the bigger picture, including underlying guidelines, principles and best practices.

Asynchronous Messaging Architectures

Asynchronous messaging architectures have proven to be the best strategy for enterprise integration because they allow for a loosely coupled solution that overcomes the limitations of remote communication, such as latency and unreliability. The trend towards asynchronous messaging has manifested itself in a variety of EAI suites as well emerging standards for reliable, asynchronous Web services. Unfortunately, asynchronous messaging is not without pitfalls. Many of the assumptions that hold true when developing single, synchronous applications are no longer valid. What is needed is vendor-independent design guidance on building robust integration architectures based on asynchronous messaging.

How can Patterns Help?

Patterns are a proven way to capture experts’ knowledge in fields where there are no simple “one size fits all” answers, such as application architecture, object-oriented design, or message-oriented integration . Each pattern poses a specific design problem, discusses the considerations surrounding the problem, and presents an elegant solution that balances the various forces or drivers. In most cases, the solution is not the first approach that comes to mind, but one that has evolved through actual use over time. As a result, each pattern incorporates the experience base that senior integration developers and architects have gained by repeatedly building solutions and learning from their mistakes. This implies that we did not “invent” the patterns; patterns are not invented, but rather discovered and observed from actual practice in the field.

The patterns on this site are by no means a complete treatment of all things integration. We focused on developing a cohesive set of patterns that would make a well rounded book. We continue to discover new patterns as part of our daily client work and hope to find the time to document them in the future.

What am I Reading Right Now?

POSA 4 Pattern-Oriented Software Architecture: A Pattern Language for Distributed Computing, Volume 4
Frank Buschmann, Kevlin Henney, Douglas C. Schmidt, Wiley, 2007

OK, I have only read an early manuscript but I already pre-ordered this one. Frank, Kevlin, and Doug cataloged common distributed systems patterns (including many of our messaging patterns) and describe their relationships in the context of an overarching pattern language. Available May 7.

 

Distributed Event-based Systems
Mühl, Fiege, Pietzuch, Springer Verlag, 2006

There is a lot of talk these days about event-driven systems being the next step beyond SOA. I am not sure where on the hype cycle this observation falls, but I have had a long-standing interest in event-driven systems. Accordingly, my eyes lit up when I discovered this title. Like most Springer books, it manages to walk the fine line between academic precision and practical relevance, that is, as long as you are not afraid of greek letters and the occasional formalism. For example, Chapter 2, titled "Basics", makes ample use of temporal logic to define the precise semantics of event-based systems. While it is certainly not a light read, this book is the first one I have seen so far that dives deep into the implementation trade-offs of event-based systems, such as routing, matching algorithms etc.

 
Integration Patterns
Integration Patterns Overview
Table of Contents
Revision History
Introduction
Preface
Introduction
Solving Integration Problems using Patterns
Integration Styles
Introduction
File Transfer
Shared Database
Remote Procedure Invocation
Messaging
Messaging Systems
Introduction
Message Channel
Message
Pipes and Filters
Message Router
Message Translator
Message Endpoint
Messaging Channels
Introduction
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
Introduction
Command Message
Document Message
Event Message
Request-Reply
Return Address
Correlation Identifier
Message Sequence
Message Expiration
Format Indicator
Interlude: Simple Messaging
Introduction
JMS Request/Reply Example
.NET Request/Reply Example
JMS Publish/Subscribe Example
Message Routing
Introduction
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
Introduction
Envelope Wrapper
Content Enricher
Content Filter
Claim Check
Normalizer
Canonical Data Model
Interlude: Composed Messaging
Introduction
Synchronous (Web Services)
Asynchronous (MSMQ)
Asynchronous (TIBCO)
Messaging Endpoints
Introduction
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
Introduction
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