If a service-oriented architecture is to be effective, we need a clear understanding of the term service. A service is a function that is well-defined, self-contained, and does not depend on the context or state of other services.
A service-oriented architecture is essentially a collection of services. These services communicate with each other. The communication can involve either simple data passing or it could involve two or more services coordinating some activity. Some means of connecting services to each other is needed.
The .Net technology introduces the SOA by mean of web services.
The SOA can be used as the concept to connect multiple systems to provide services. It has it's great share in the future of the IT world.
According to the imaginary diagram above, we can see how the Service Oriented Architecture is being used to provide a set of centralized services to the citizens of a country. The citizens are given a unique identifying card, where that card carries all personal information of each citizen. Each service centers such as shopping complex, hospital, station, and factory are equipped with a computer system where that system is connected to a central server, which is responsible of providing service to a city. As an example when a customer enter the shopping complex the regional computer system report it to the central server and obtain information about the customer before providing access to the premises. The system welcomes the customer. The customer finished the shopping and then by the time he leaves the shopping complex, he will be asked to go through a billing process, where the regional computer system will manage the process. The payment will be automatically handled with the input details obtain from the customer identifying card.
The regional system will report to the city (computer system of the city) while the city will report to the country (computer system of the country).
Source:
http://www.service-architecture.com/web-services/articles/web_services_explained.html
Web Service
Web Services refers to the technologies that allow for making connections. Services are what you connect together using Web Services. A service is the endpoint of a connection. Also, a service has some type of underlying computer system that supports the connection offered.
The Web Services Description Language (WSDL) forms the basis for Web Services. The following figure illustrates the use of WSDL. At the left is a service provider. At the right is a service consumer. The steps involved in providing and consuming a service are:
- A service provider describes its service using WSDL. This definition is published to a directory of services. The directory could use Universal Description, Discovery, and Integration (UDDI). Other forms of directories can also be used.
- A service consumer issues one or more queries to the directory to locate a service and determine how to communicate with that service.
- Part of the WSDL provided by the service provider is passed to the service consumer. This tells the service consumer what the requests and responses are for the service provider.
- The service consumer uses the WSDL to send a request to the service provider.
- The service provider provides the expected response to the service consumer.
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