Unit 1: The Components in Web Application

The Components in Web Application 

- Web Server e.g. Apache
- Web client e.g. Firefox
- HTTP (HyperText Transfer Protocol)
- URL (Universal Resource Locator)
ex. http://localhost:8080/FirstServletProject/jsps/hello.jsp

 A web Server is a software that can process the client request and send the response back to the client. For example, Apache is one of the most widely used web servers. 
 A web client is a software that helps in communicating with the server. Some of the most widely used web clients are Firefox, Google Chrome, Safari etc.

HTTP (HyperText Transfer Protocol) is the communication protocol between server and client.
 URL is an acronym of Universal Resource Locator and it’s used to locate the server and resource. Every resource on the web has its own unique address.
http://localhost:8080/FirstServletProject/jsps/hello.jsp
HTTP:// – This is the first part of URL and provides the communication protocol to be used in server-client communication.
localhost – The unique address of the server, most of the times it’s the hostname of the server that maps to the unique IP address.
8080 – This is the port on which server is listening, it’s optional and if we don’t provide it in URL then request goes to the default port of the protocol. Port numbers 0 to 1023 are reserved ports for well-known services, for example, 80 for HTTP, 443 for HTTPS, 21 for FTP etc.
FirstServletProject/jsps/hello.jsp – Resource requested from server. It can be static html, pdf, JSP, servlets, PHP etc.

Java Servlet and JSPs are server side technologies to extend the capability of web servers by providing support for dynamic response and data persistence.