Web services

Web services can be viewed as web applications that don't include a presentation layer. Service-oriented architecture allows a web service provider to integrate easily with the consumer of that service. Web services enable different applications to share data and functionality among themselves. They allow consumers to access data over the internet without the application knowing the format or the location of the data.

This becomes extremely critical when you don't want to expose the data model or the logic used to access the data, but you still want the data readily available for its consumers. An example would be a web service exposed by a stock exchange. Online brokers can use this web service to get real-time information about stocks and display it on their own websites, with their own presentation style and branding for purchase by end users. The broker's website only needs to call the service and request the data for a company. When the service replies back with the data, the web application can parse the information and display it.

Web services are platform independent. The stock exchange application can be written in any language, and the service can still be called regardless of the underlying technology used to build the application. The only thing the service provider and the consumer need to agree on are the rules for the exchange of the data.

There are currently two different ways to develop web services:

• Simple Object Access Protocol (SOAP)
• Representational State Transfer (REST), also known as RESTful web services.