What are web services? Explain role of SOAP in Web services

Web services are software systems designed to support interoperable machine-to-machine interaction over a network. They have an interface described in a machine-processable format, specifically Web Services Description Language (WSDL). Other systems interact with the web service in a manner prescribed by its description using SOAP messages, typically conveyed using HTTP with an XML serialization in conjunction with other web-related standards.

SOAP (Simple Object Access Protocol) is a messaging protocol that allows programs running on disparate operating systems to communicate with each other. It uses XML for its message format, which allows programs to communicate with each other even if they are not on the same platform.

The role of SOAP in web services is crucial. It provides a way to communicate between applications running on different operating systems, with different technologies and programming languages. It provides the following:

1. Extensibility: SOAP allows for any programming model and is extensible enough to allow for future upgrades.

2. Neutrality: SOAP can operate over any protocol such as HTTP, SMTP, TCP, or even JMS.

3. Independence: SOAP allows for any programming model and doesn't tie the client to the server and vice versa.

In summary, SOAP is a protocol for exchanging structured information in web services using XML. Its main function is to ensure that programs built on different platforms and programming languages can exchange data in a straightforward manner. It does this by using the HTTP protocol and XML as the format for data exchange.