Web Service is defined as the provision of a service that can be accessed through the Internet. It represents a well-defined business logic allowing interaction with clients.
These clients send well-defined requests and receive:
- synchronous responses, in which the client is blocked waiting for the service to complete its execution, and
- asynchronous, with no need to wait for the execution to end.
Services exposed as Web Services have business logic that must encapsulate rules or functionalities that represent business rules. They must be published and accessed through a standard language of publication and a specific communication protocol.
A Web Service has a weakly coupled internal structure, that is, the implementation of the service can change at any time without affecting its use by the client.
By adopting this type of technology we can make the systems better modularized and reach Levels of integration. It supports remote procedure calls (RPC), which allows the client to invoke remote object operations using an XML-based protocol. Each operation must optionally expose input parameters and set its return type.
Components of a Web Service
HTTP protocol: standard protocol for transmission of data over the Internet.
XML: standard format for information exchange. It has strict syntax and lightness in the data storage. Main element of the Web Services technology.
Simple Object Access Protocol (SOAP): Provides a standard packaging framework for transporting XML documents over the Internet.
Web Service Description Language (WSDL): XML technology that describes in a standardized way the interface of a Web Service. It determines:
- how the parameters of the external call input and output,
-the structure of the functions,
-the nature of the call (input / output and output only),
- the connection protocol with the service are represented, and
- how clients interact and execute services.
Universal Description, Discovery, and Integration (UDDI): describes a worldwide registry of services and serves as integration, advertisement, and service discovery. You can use this registry to discover services available on the Internet.
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