Thomas Erl

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For a complete list of the co-authors and contributors, see the end of the article. The following section demonstrates the creation of a simple "Hello World" service in a Windows Azure hosted application. Note: If you are carrying out the upcoming steps with Visual Studio 2008, you will need to be in an elevated mode (such as Administrator). A convenient way of determining whether the mode setting is correct is to press the F5 key in order to enter debug mode. If you receive an error stating "the development fabric must be run elevated," then you will need to restart Visual Studio as an administrator. Also, ensure the following on your SQL Express setup: SQL Server Express Edition 2008 must be running under the ‘.\SQLEXPRESS' instance Your Windows account must have a login in .\SQLEXPRESS Your login account is a member of the sysadmin role If SQL Express isn't confi... (more)

A Look Ahead to the Service-Oriented World

BEA recently announced that it is broadening its SOA consulting practice, and that it has created a tool companies can use to learn about SOA and figure out how prepared they are to transition to the new architectural model. While BEA and other major vendors, such as IBM and Microsoft, continue to deepen their investments in SOA, many of us are still struggling to understand what SOA actually is. How well do you know SOA? If you were asked to write a definition right now, what would it be? One of the challenges has always been to distinguish SOA from a standard distributed archit... (more)

Paths to SOA

Many are comparing notes on two well-publicized paths to achieving SOA. The bottom-up approach is currently the most common variety, where Web services are created on an "as need" basis to fulfill mostly integration-related requirements. These services are typically application specific and simply re-create traditional integration channels over the open Web services communication framework. The top-down approach, on the other hand, is one of analysis, deep thought, and patience. Service-orientation is infused into the business process layer so that services can be modeled in ali... (more)

Introducing SOA Design Patterns

Originally inspired by techniques used to design buildings and cities, and popularized by the Gang of Four during the mainstream emergence of object-orientation, design patterns have seen us through the various shifts in architecture, technology, and, of course, design. Pattern catalogs have periodically emerged, one building on the other, and each revealing a set of problem-solving techniques and providing invaluable insights as to how and when those techniques should be used to help us attain our design goals. SOA has its own history, having risen out of a haze of ambiguity to e... (more)

SOA Pattern of the Week (#1): Service Façade

One of the fundamental goals when designing service-oriented solutions is to attain a reduced degree of coupling between services, thereby increasing the freedom and flexibility with which services can be individually evolved. Achieving the right level of coupling "looseness" is most often considered a design issue that revolves around the service contract and the consumer programs that form dependencies upon it. However, for the service architect there are opportunities to establish intermediate layers of abstraction within the service implementation that further foster reduced... (more)