Introduction to Web server, web browser and HTTP

Introduction to Web server, web browser and HTTP



A web application is unlike a standard Windows application. It does not run in a single process on a single machine. Instead, it is typically hosted on a Web server and accessed via a Web browser on a client machine. The communication between the web server and web browser is sent by using HTTP.


The communication process between browser and server can be categorized into the following steps.



1. A user uses his/her Web browser to initiate a request for a Web server resource.



2. HTTP is used to send a GET request to the Web server.



3. The Web server processes the GET request on the server.



4. The Web server then sends a response back to the Web browser. The HTTP protocol is used to send the HTTP response back to the Web browser.



5. The user’s web browser then processes the response (typically HTML and JavaScript) and renders the Web page for display to the user.



6. The user may then enter data and perform an action such as clicking submit button that cause his/her data to be sent back to the Web server for processing.



7. HTTP is used to POST the data back to the Web server.



8. The web server then processes the POST request.



9. The web server then sends a response back to the Web browser. HTTP is used to send the HTTP response to the Web browser.



10. The web browser again processes the response and displays the Web page to the user. This process is repeated over and over during a typical Web application session.



The Web Server’s Role



The first Web servers were responsible for receiving and processing simple user requests from browsers via HTTP. The Web server handled its request and sent a response back to the Web browser. The Web server then closed any connection between it and the browser and released all resources that were involved with the request



The Web Browser’s Role



The Web browser provides a platform-independent means of displaying Web pages that were written in HTML. HTML was designed to be able to render information on any operating system while placing no constraint on the window size.



Understanding the Role of Hypertext Transfer Protocol



HTTP is a text-based communication protocol that is used to request Web pages from the Web server and send responses back to the Web browser. HTTP messages are typically sent between the Web server and Web browser using port 80, or port 443 when using Secure HTTP (HTTPS).