Explain Web Services in detail.

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 Web Services

  • Web service refers to the software system designed to support interoperable machine-to-machine or web interaction over the computer network and World Wide Web. A server running on the network listens for requests at a certain port and serves web content such as HTML, JSON, XML, etc. Web services are self-contained, modular, distributed, dynamic programs that may be specified, published, located, or invoked through a network to produce products and services. These apps might be local, distributed, or based. Web services are client and server applications that interact using the HyperText Transfer Protocol (HTTP) over the World Wide Web (WWW).
  • Web Service is "a software system designed to support interoperable machine-to-machine interaction over a network". Web services, as defined by the World Wide Web Consortium (W3C), provide a common mechanism for interoperating across software applications running on various platforms and frameworks. Web services are distinguished by their high interoperability and extensibility, as well as machine-processable descriptions made possible by the use of XML.
  • Any program, application, or cloud technology that enables standardized web protocols (HTTP or HTTPS) to interoperate, interact, and exchange data messages - commonly XML (Extensible Markup Language) across the internet is considered a web service. Web services are data interchange systems based on XML that use the Internet for A2A (Application-to-Application) communication and interfacing. Programs, messages, documents, and/or objects are all involved in these processes. Figure 8.1 depicts a web service model consisting of three main entities: Service provider, Service Consumer and Service Broker, each performing publish, find and service registration roles respectively.
  • A key aspect of web services is that applications developed in different languages connect by transferring data over a web service between clients and servers. A client invokes a web service by submitting an XML request, and the service responds with an XML response. Service-Oriented Architecture (SOA) is frequently related to web services. For example, a client may activate a web service by submitting an XML message and then waiting for an XML answer. Because all communication is done in XML, web services are not limited to a single operating system or programming language  - Java may communicate with Perl, and Windows programs can communicate with Unix programs. 

A web service must perform the following functions:

  • Accessible through the Internet or intranet networks
  • An XML communications protocol that is standardized
  • Unconstrained by a particular operating system or programming language 
  • Self-description using the standard XML language
  •  Discoverable through a simple location method

A web service allows several programs to communicate using HTML, XML, WSDL, SOAP, and other open standards. XML tags the data, SOAP transports the message, and WSDL explains the accessibility of the service. For instance, a web service lies between two sets of Java, .Net, or PHP programs, allowing them to connect across a network. A java program, for example, communicates with Java, .Net, and PHP programs on the other end via a web service communicating in an independent language.

Characteristics of Web Services

  • Web services are XML-Based Web service is Loosely Coupled
  • Web service can be Synchronous or Asynchronous 
  • Web service supports Remote Procedure Calls (RPCS)
  • Web service supports Document Exchange 

Example of Web Services

Web template, JSON-RPC, JSON-WSP, Web Services Description Language (WSDL), Web Services Conversation Language (WSCL), Web Services Flow Language (WSFL), Web Services Metadata Exchange (WS.MetadataExchange), XML Interface for Network Services (XINS), etc. are some more examples of web services.




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