ServiceTechMag.com > Archive > Issue XXIX: May/June 2009

Issue XXIX May/June 2009

SOA and the XML Factor:
Designing Service-Oriented Solutions with Extreme XML Compatibility

Ronald Murphy

Ronald Murphy

Interfaces of all kinds are subject to change. When we make a change to the operations or data offered by a service contract, this change will have an impact the consumers of the interface. In the world of SOA and service-orientation, attention to interface - or service contract - versioning is paramount because the average service-oriented enterprise ends up establishing many more dependencies on a published technical interface than traditional, silo-based application environments. One change can therefore have a ripple effect by impact numerous service consumers, each of which may have been composing the service for a different purpose. This article explores common service contract versioning challenges and proposes different approaches with an emphasis on helping you achieve "extreme" XML compatibility. To make a change "backwards compatible," we try to ensure that the data and operations already being used will continue to work. If this doesn't happen, any existing coded uses will need to be updated - usually meaning rebuilding significant parts of the service logic. The first-order effects of this consequence are consumers that don't appreciate the inconvenience you have caused them - and this effect only gets worse with repetition! There are a number of second-order effects as well: You can't usually expect consumers to upgrade instantly. Many of them operate on their own fixed release cycles. The more service consumers you have, the more the diversity in the release cycles...


Principles for Implementing a Service-Oriented Enterprise Architecture

Tyson Brooks

Tyson Brooks

This article provides four key principles and actions an organization can undertake for implementing a Service-Oriented Enterprise Architecture (SOEA). SOEA adopts the concepts used in enterprise architecture and service-oriented systems design and adapts them to the enterprise level using service-oriented computing (SOC). A SOEA should provide the guidance to enterprise transformation of the organizational, business process management/modeling and reengineering, enterprise resources and information technology (IT) systems and application development in support of the organization. Although technical in nature, the SOEA form of architecture does not focus solely on network (i.e. infrastructure, core services), information (i.e. data, enabling services), and resources (i.e. providers and consumers of services and data) architectural views. One of the most intriguing new information systems methodological approaches in IT to come along is SOA. The emergence of the SOC paradigm and Web service technology, in particular, has aroused enormous interest in SOA [REF-1]. As organizations grow and become more complex, consumers make greater demands of their business functions and models. Organizations have continually enhanced and expanded their IT infrastructures more and more as information has become available in electronic form. SOA activities focus on hypothesizing new ways of working by developing practical implementation scenarios that build on and exploit existing information systems and networking technology. Organizations have recognized that collecting and disseminating data represents...


Workflow-Enabled Services with Windows Workflow Foundation

Nitin Gandhi

Nitin Gandhi

A workflow is a collection of activities that describes a business process. Modeling business processes is a key requirement for developing service compositions. Workflows provide a way of describing business process logic by expressing the order of execution and relationships between various activities. This article, comprised of introductory pre-release content from the upcoming SOA with .NET book [REF-1], introduces the Windows Workflow Foundation (WF) and explores how it can be used to model and implement workflow logic in support of carrying out that logic via composed services. In some cases the business process is automated, while in other cases it may involve human intervention. Very often it is possible to describe a process as a discrete series of steps that may involve people and software. A workflow is a set of activities that co-ordinate people and software. The duration of the business process is an important consideration when modeling a workflow; some business processes may involve systems and human intervention and potentially run for several hours, days, or even weeks. Windows Workflow Foundation (WF), introduced in .NET 3.0, was created to meet these requirements, as shown in Figure 1. Windows Workflow Foundation (WF) is the single workflow technology for Windows. At the core, WF enables execution of steps required to complete a business process and is used to construct workflow-enabled applications on the Microsoft platform. Workflow solutions are becoming increasingly important as the process-oriented view of software grows...


Towards an SOA Manifesto

Thomas Erl

Thomas Erl

The service-oriented architectural model and the service-orientation paradigm have reached a stage of maturity where the principles, intentions, and ambitions that embody their underlying philosophy and goals can be expressed in a formal manifesto. On October 23, 2009 at this year's 2nd International SOA Symposium in Rotterdam, the "Towards and SOA Manifesto" working group will be following in the footsteps of the agile community by announcing the SOA Manifesto for the first time...


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