1/ What are Web services?
A Web Service is can be defined by following ways:
- is a client server application or application component for communication.
- method of communication between two devices over network.
- is a software system for interoperable machine to machine communication.
- is a collection of standards or protocols for exchanging information between two devices or application.
Let’s understand it by the figure given below:
As you see the figure, java, .net or PHP applications can communicate with other applications through web service over the network.
(Refer from http://www.javatpoint.com/what-is-web-service)
2/ Components of Web Services
The basic web services platform is XML + HTTP. All the standard web services work using the following components:
- SOAP (Simple Object Access Protocol)
- UDDI (Universal Description, Discovery and Integration)
- WSDL (Web Services Description Language)
3/ How does a Web service work?
A web service enables communication among various applications by using open standards such as HTML, XML, WSDL and SOAP. A web service takes the help of:
- XML to tag the data
- SOAP to transfer a message
- WSDL to describe the availability of service.
You can build a Java-based web service on Solaris that is accessible from your Visual Basic program that runs on Windows.
You can also use C# to build new web services on Windows that can be invoked from your web application that is based on Java Server Pages (JSP) and runs on Linux
Consider a simple account-management and order processing system. The accounting personnel use a client application built with Visual Basic or JSP to create new accounts and enter new customer orders.
The processing logic for this system is written in Java and resides on a Solaris machine, which also interacts with a database to store information.
The steps to perform this operation are as follows:
- The client program bundles the account registration information into a SOAP message.
- This SOAP message is sent to the web service as the body of an HTTP POST request.
- The web service unpacks the SOAP request and converts it into a command that the application can understand.
- The application processes the information as required and responds with a new unique account number for that customer.
- Next, the web service packages the response into another SOAP message, which it sends back to the client program in response to its HTTP request.
- The client program unpacks the SOAP message to obtain the results of the account registration process.
(Refer from https://www.tutorialspoint.com/webservices/what_are_web_services.htm)