Chapter 1 Service-Oriented Architectures At the core of (Web design seattle)
Chapter 1 Service-Oriented Architectures At the core of a service-oriented architecture lies the concept of service. A simplistic definition of service is a group of related components that carry out a given business process function, for example transferring funds between banks or booking an itinerary. A service-oriented architecture (SOA) thus is a paradigm focusing on development of services rather than piecemeal components such that these services provide a higher level of abstraction from a functional standpoint. Of course, there are more properties to SOA than mere coarse-granularity. One such characteristic property of SOA is that they are autonomous in nature. These independent entities can interact with others in spite of differences in the way they have been implemented or the platform they have been deployed on. The notion of putting together (integrating) such autonomous and loosely coupled services to address the changing business needs has a huge value proposition and it is well on its way to realization with the emergence of various choreography, orchestration and collaboration technologies such as WS-BPEL, EbXML BPSS, and WS Choreography. SOA and Web Services The terms Web Services and SOA are often used interchangeably and wrongly so. SOA is a paradigm. There are many possible ways of building software so that it implements salient features of SOA, mainly coarse granularity and loose coupling. One such way is Web services. Web Services are a group of XML technologies, which can be used for implementing SOA. Core Web service technologies mainly SOAP and WSDL form the basis of most of these Web service implementations today. Simple Object Access Protocol (SOAP) is an XML-based application-level protocol intended for exchanging information in a distributed network. SOAP supports both the models of distributed computing: RPC as well as document- style messaging. RPC style SOAP allows remote invocation of operations. Parameters and return in/out values of these operations are serialized in XML. Whereas, in document-style SOAP because an operation s input and output are XML, serialization of parameters and return value to XML is not needed. Although most of the Web service applications use SOAP over HTTP today, the standard does not preclude using SOAP over other IP protocols, such as SMTP. SOAP 1.2 is a W3C recommendation at the time of this writing. Web Service Description Language (WSDL) is an XML-based metadata standard that is used to describe the service interface in terms of the operations it supports, the parameters that the operations accept, and their return values in case of SOAP RPC, the XML schema that the input and output messages to the operations in case of document-style SOAP as well as service binding information in terms of the communication protocols, ports, service URL, and so