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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)

SOA Pattern of the Week (#5): Service Decomposition

A service inventory is a living body of services that individually will need the freedom to evolve independently over time. What we learned when documenting the SOA design pattern catalog is that there are patterns that emerged not only at design-time but also during this post-implementation evolutionary stage in a service's lifecycle. There is one common scenario that repeatedly surfaced in many projects: When we model and design services during early stages of SOA adoption we are constrained by current infrastructure and technology. These constraints require that we limit the s... (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)

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 (#3): Domain Inventory

Enterprise-wide harmonization is a desirable and ideal target state that fully supports pretty much everything SOA and service-orientation stand for. For those that have achieved such a state, bless your standardized hearts. You have accomplished something that has eluded many others. However, not attaining this state does not mean you cannot successfully adopt SOA. In some circles it has become common to view an SOA initiative as an all-or-nothing proposition that demands an uncompromising commitment to an enterprise-wide transformation effort. For those that subscribe to this vi... (more)