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 valid for most integration tools and standards such as IBM WebSphere MQ, TIBCO, Vitria, SeeBeyond, WebMethods, BizTalk, JMS, MSMQ, Web Services etc.

This site is maintained by Gregor Hohpe. I lead the Enterprise Integration practice for ThoughtWorks, an application development and systems integration firm. I hope you find this material useful. Feel free to contact me with suggestions or feedback. Also, my company happens to be pretty good at helping clients build integration solutions, so don't hesitate to contact me if you are interested in our services.

Enterprise Integration Patterns - The Book

For quite a while I have been feeling that 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.

Martin Fowler noticed the same when he wrote Patterns of Enterprise Application Architecture. As a result, back in 2001 Martin and Kyle Brown started a series of discussions on messaging patterns. In early 2002 I joined the discussions and started collecting more patterns based on my ongoing client work. I teamed up with Bobby Woolf to document 65 integration patterns (see the links on the right). After multiple rounds of reviews, writer's workshops and conference presentations, the hard work bore fruits and the patterns catalog is now (Oct 2003) available in book form from Addison-Wesley, titled Enterprise Integration Patterns.

The book 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, Chief Architect, IQ Navigator
[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?

Somehow this book managed to get to market without me noticing. Springer Verlag is known for its in-depth academic books. This one is no exception with three Ph.D.'s among the authors. Nevertheless the book is pleasant to read and is chock full of real information on distributed systems architecture, with a particular focus on Web services. The book explains the rationale behind many of the Web services standardization efforts. For example, the book dedicates a whole chapter each to service coordination and service orchestration. The book is on the higher end of the price scale but the amount of content it is definitely worth it.