Web service is intended for computers or machines across different networks to share data and services through applications that use the same programming language, which consists of an array of system protocols and rules. This allows interoperability among a number of computer systems that may be produced by different companies. The World Wide Web Consortium (W3C), which was developed for standardized protocol of the world wide web, defines web service as "a software system designed to support interoperable machine-to-machine interaction over a network."
Web services are used to build secure applications that have the accessibility from any computer system environment. They help with the intention of open system, which is the idea that applications and software have a foundation based on the same protocols that help make it available to anybody accessing the internet, and also help businesses, institutions, and government organizations better communicate and serve customers and clients. Web services help with Service Oriented Architecture (SOA), which is the notion of interacting software being able to process and exchange data easily.
Important to knowing web services is learning about HTTP & XML. HTML and XML are markup languages. Markup languages are instructions that specify how data and information should be structured on a website. HTML or Hypertext Mark-up Language is the language used for web pages, which focuses on how the data is displayed on web pages. XML is Extensible Markup Language, which was developed to further enhance markup language, and focuses on transporting and storing data.
Application Programming Interface helps with software applications. API focuses on the building and constructing of application software. The two types of ways that application programming interface is written is language-dependent and language-independent. These terms refer to the features that are available, which is how many different programming languages that it can be written in, which can affect the convenience of using applications.
There are XML specifications, messaging, meta data exchange, security, privacy, reliable messaging, resource, web services interoperability organization (WS-I), business process, transaction, management, presentation oriented, and draft specifications to name a few.
· XML Signature
· XML Encryption
· XML Schema
· WS Policy
· WS-I Basic Profile