Customer Reviews

SOA Design Patterns (The Prentice Hall Service-Oriented Computing Series from Thomas Erl)

5 star:		(15)
4 star:		(5)
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This text provides a wonderful and thorough explanation of base SOA principles. The core definitions are concrete, base references well chosen and contains many useful points for consideration. The key topics are covered in a logical structure and approached in logical order. This makes the text much more useful for building a foundation on SOA than its competitors.

However, the text clearly overstates the issues. The use of non-illuminating case studies coupled with needlessly complex re-definition of key terminology makes this reference sheer overkill. This book provides a key example of taking simple concepts and turning them in on themselves to make them appear much more complex than they really are. I am unsure whether this is because of the author's desire to become the biblical reference that Distributed Systems: Principles and Paradigms is or if it is simply because the author wants to make the topic seem more intellectually difficult to grasp than it really is.

I do not want to take away from the value of the content covered, but there are much more succinct and light-hearted publications that will lead you to the same base understanding. It is VERY wordy and over-stated, but it is worth having in your stack of SOA, Web Services, etc. etc. etc. reference stack. If for nothing else, than key citations and consideration points.

Possibly the most value thing I got from this book was the ability to ask additional questions and put key things to consideration that would have otherwise been missed. Sometimes the most obvious things are taken for granted and hence overlooked -- this book touches on that wonderfully.

To summarize: a wonderful book with a thorough examination of core SOA principles, but it breaks the primary principle of "I'm sorry this letter is so long, I didn't have time to make it shorter."

I enjoyed the author's/publisher's other books on the topic, but this one was a bit of a disappointment - perhaps it should have been first on my list instead of close to last. I highly recommend ignoring the fruitless illustrations/diagrams and sticking to the text, as well.

I think this book shares the same defect as the rest of the books in the SOA/Erl series: it's essentially an over-modeled collection of diagrams and abstractions with little real information, wrapped in advertising for the Erl/SOA brand. The modeling reaches the point of absurdity when models are given to depict where you are in the process or pattern, and when diagrams are used in place of concise text. (I kid you not; there's one "pattern" where the text makes the vapidly obvious claim that large problems can be broken into smaller ones, and large solutions can be broken into smaller ones, then proceeds to model that claim with two large diagrams of large problems and large solutions being broken into smaller problems and smaller solutions, respectively.)

Each pattern has lots of abstract claims and diagrams, and then is usually followed by a snippet of an XML configuration file with the one line that characterizes the "pattern" in bold. IOW, the whole pattern could have been reduced to one paragraph with an XML snippet. I don't have the book in front of me, but to give you an example of what I'm talking about, imagine a whole chapter on the "Services Security Pattern" with fifty pages of text and block diagrams talking at a high level about how security is important (including large diagrams that model concepts like [User] -> [Login] -> [Authentication], followed by an XML web service configuration file snippet that enables the use of WS-Basic.

I get the impression that these books are just promotional material for the class that Erl & Co. are trying to get readers to pay for. The few books in this series that I've read or perused seem to plug Erl's SOA brand, plug his web site, plug his courses, and then spend 800 pages describing a few technical concepts at level appropriate for the sales team or the CIO. The technical content of this book could probably be distilled down to a chapter or two.

If you're an architect or developer, I'd recommend skipping this book and the rest of the series.

In summary, the SOA Design Patterns book isn't structured with the same rigor and coherence as other Design Patterns books. The content is unusually wordy and repetitive. There are a lot of diagrams but a majority of them provide little insight. The book takes well known concepts in computer science and regurgitates them as design patterns essentially taking what is obvious and making them obscure. Despite the poor quality of most of the book, its saving grace is that there are but a few patterns that have been submitted by contributors that are of a high quality.

However considering the pervasively poor quality of SOA books in general, I'm going to say it is one of the more valuable SOA books. Even if this bar is extremely low, this is of the few SOA books where you can indeed find some true nuggets of wisdom. (The book's website has a lot more interesting patterns that weren't published with the book) However, you have to dig very hard and long to find them because the map that is provided can is deliberately obscuring and more of a hindrance than an aid. Read it only if you know what to look for.

More details here: [...].

The book SOA Design Patterns by Thomas Erl offers a very clean and straight-forward explanation of to the many different facets and options of implementing SOA.

I particularly enjoyed Chapter 13: Service Security Patterns and Chapter 20: Service Interaction Security Patterns. Discussed intelligibly in these chapters are security standards such as WS-Security, SAML, WS-BPEL (which goes towards data integrity), XML Encryption and XML Signature. It was for me a good bridge between security concepts I have applied in different areas (such as PKI, Kerberos, etc.) and how to implement these same solutions in a service-oriented architecture.

In addition to the two chapters dedicated to security, I also found the following sections interesting from a security perspective.

Chapter 19-3: Atomic Transaction Services
All tasks, or web services, within a transaction must be followed by an acknowledgement to indicate that the task completed. If no such commit is received by task coordinator defined for the transaction, all the tasks within the transaction can be rolled back (or other mitigating actions can take place.) The web service specifications WS-Coordination and WS-Atomic Transactions can be utilized to employ this safer method of transaction management.

Chapter 19-5: Compensating Service Transaction
This allows for a web service to have an "undo" event, defined at the task level, which can protect the encompassing transactions against individually failing web services. These tasks can operate asynchronously, and the other inline web services are notified when an exception occurs so that they can handle the event appropriately without sacrificing the entire transaction. This helps build robust exception management and defend against resource starvation attacks.

Chapter 18-9: Reliable Messaging
The method helps ensure message delivery. Messages can be tracked via acknowledgements similar to TCP/IP packets, and persist messages during failure conditions. Reliable messaging can help protect against data integrity and service availability attacks.

Chapter 12-5: Partial Validation
At first this sounds like disabling some of the data validation performed by a web service, which is definitely discouraged (remember, all input is evil), but instead what this does is use a language like XPath to filter out unnecessary data from a message so that only a subset of the data is validated; the omitted data is dropped off before the validation phase. This can be used as an optimization technique.

Chapter 18-6: Service Callback
This allows for asynchronous web service calls, which can be helpful for web services that can take a long time to process and respond. A callback address is provided so that the web service can be polled at intervals to see if it is ready to return data. This can also be used to protect against resource starvation attacks.

While the book is sometimes light on implementation details (the author maintained platform agnosticism throughout) it definitely provides a good starting point for managers, coders and architects by including sample SOAP headers, messages and WSDL definitions. What I also appreciated is that keywords are followed by the page number in parenthesis to easily look up the definition of that term. Lastly, not only is the book filled with useful information, but the inside covers themselves is a pattern list reference.

The book may be a challenge to read cover to cover, but is an excellent reference. It is a bookshelf staple for anyone implementing, or interested in, SOA.

Much better than Erl's Service Oriented Architecture, but Erl still has a penchant for repetition, resulting in a bloated book. And the "case studies" don't add much insight. The book does serve a purpose of most patterns books in naming the patterns and providing for a common terminology. I'm moving on to SOA in Practice, which is already much more concrete in just the opening chapters.

Note: Read on Kindle DX, text was well formatted but many of the diagrams were difficult to understand since there is a heavy reliance on color-coding of the diagram blocks. This is not a big loss, the diagrams did not add a lot. However, PC and iPhone Kindle software do present the diagrams in color when needed.

There are only a few who understand service-oriented computing like Thomas Erl. But, Erl stands alone when it comes to Excellence in SOA publications! "SOA Design Patterns", is a milestone in SOA literature. It is a comprehensive design pattern catalog that documents a master pattern language for SOA and serves as an invaluable multi-dimensional reference for developing and evolving an enterprise SOA portfolio.

While the depth and breadth of the design patterns alone is a remarkable body of work, a key strength of this publication lies in its structural presentation of the content. First, a simple, well structured pattern notation is used to represent different types of design patterns, pattern application sequences and pattern relationships.

Second, the format used for presenting each design pattern by far is the best I have ever encountered. Each pattern is described using a well organized profile summary format, which allows the reader to absorb the information rather than trying to mentally process and organize the material.

Finally, the detailed figures that reinforce the textual description of the specific design issue and solution are excellent, as are the Case Study examples. Each design pattern presentation ends with an example of how the specific pattern was applied to solve a "real world" design challenge.

"SOA Design Patterns" has already proven to be an invaluable resource in the design of our organization's SOA portfolio that provides health information exchange services to all providers in California. This exceptionally valuable book is not a "nice to have" publication for one's technology bookshelf, but a "Must Have"! Thanks once again Thomas!!

M Allison, Chief Technology Officer, California Regional Health Information Organization (CalRHIO)

I'm a fan of Thomas Erl's work. In general, he does an excellent job of speaking about SOA in plain English and giving examples that are practical and help developers and architects alike get started. His latest work is just as well-written and practical, and an excellent counterpoint to his Principles of SOA book.

With SOA Design Patterns, Erl has made a very valuable contribution to the SOA body of knowledge. Working with many practitioners over the span of many years, he has collected the wisdom of the industry and presented it in a structured and usable way. And the patterns have been collected and refined through a very open and transparent community process.

But the contribution to the field doesn't end with the book. What makes this work different from other works, besides the comprehensive and exhaustive content is the support sites. The official book site at[....] doesn't have much besides links to the other books/topics in the series, but the community site at [....] has a wealth of information

on the patterns, as well as links to podcast interviews with the authors.

Overall, and excellent addition to your SOA library.

We are in the third year of our SOA adoption, and the Thomas Erl SOA books have been an invaluable resource for that effort. "SOA Design Patterns" is an excellent addition to Erl's SOA series. This book is valuable in both its breadth and its depth; the book lucidly presents many (80+) thoroughly researched SOA patterns, and for each pattern includes rationale behind the pattern and a clear case-study example. As with the Gang of Four patterns and OO development, the benefit is that most of the problems you will encounter in your own SOA initiative will have already been solved; understanding and applying these SOA patterns to your SOA will help enable the success of your effort, and ensure that both your service architecture and development follow proven approaches.

Once again, thank you Thomas Erl.

I work for the IT department of a medium-sized company as a technical architect. We are in the middle of an SOA adoption, and this book has been immensely helpful to us. We are using information from the book to "get it right" the first time, so that we can begin our SOA using the correct patterns, rather than learning as we go and ending up with legacy systems that are difficult to maintain.

Mr. Erl, thanks for this great book!

If you are assembling a SOA team of any size - one of the first immediate challenges is establishing clear communications.

How to quickly and efficiently solve the challenge of adopting a set of common terms, a common lexicon for concepts, and a library of reusable architectural patterns?

SOA Design Patterns is an excellent reference for a team to adopt as an initial stake-in-the-ground. Later you can evolve your own library of patterns - extending upon this excellent body of work.

Much of this material will be known by some team members - but the thoroughness of the text provides a great level-set when assembling a team of mixed levels of experience.