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Thomas Erl

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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 alignment with business models. The models themselves may need to be built or further refined in order to fully incorporate service-orientation principles. Then, of course, there's the middle ground - an approach that tries to balance the requirements of the top-down strategy with the efficiency... (more)

SOA Pattern of the Week (#2): Non-Agnostic Context

Should a service only be considered a service if it's reusable? The answer to this question, as asserted by this pattern, is a firm "no." While agnostic services (services providing multi-purpose logic with reuse potential, as per the Agnostic Context pattern), receive the most attention during service modeling and design phases, it can often be short-sighted to focus only on agnostic service logic. Non-agnostic logic represents any type of functionality that is unique to a given business process or task. In other words, non-agnostic logic is single-purpose in nature and therefo... (more)

SOA Pattern of the Week (#4): Service Normalization

Like data normalization, the Service Normalization pattern is intent on reducing redundancy and waste in order to avoid the governance burden associated with having to maintain and synchronize similar or duplicate bodies of service logic." You can see it introduces the Pattern on our publisher page. When designing data architectures, you can easily end up with different databases or even different database tables containing the same or similar data. This has been the root of many well documented data maintenance and quality issues that helped establish data normalization as widel... (more)

Cloud Computing, SOA and Windows Azure - Part 3

For a complete list of the co-authors and contributors, see the end of the article. A cloud service in Windows Azure will typically have multiple concurrent instances. Each instance may be running all or a part of the service's codebase. As a developer, you control the number and type of roles that you want running your service. Web Roles and Worker Roles Windows Azure roles are comparable to standard Visual Studio projects, where each instance represents a separate project. These roles represent different types of applications that are natively supported by Windows Azure. There ... (more)

Cloud Computing, SOA and Windows Azure - Part 4

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 Studi... (more)