Write a program to evaluate a postfix expression.
2.2 The Web and HTTP HTTP - Hypertext transfer protocol, it is the Web’s application-layer protocol. It is implemented in two programs, a client and server. o Web browsers (Firefox, chrome, IE, etc.) implement the client side o Web servers (Apache, Microsoft Internet Information Server, etc) implement the server side Http defines how Web clients request Web pages from Web servers and how servers transfer Web pages to clients. HTTP uses TCP as its underlying transport protocol HTTP is a stateless protocol, which means that HTTP servers maintain no information about its clients. For example, if someone clicks on a link 10 times, the server sends that object to the client 10 times. Non-Persistent and Persistent COnnections o Non-persistent - Series of requests made between the client and server are sent over separate TCP connections. o Persistent - Series of requests made between the client and server are sent over the same TCP connection o Round trip time - The time it takes for a small packet to travel from client to server and then back o Default mode of HTTP uses Persistent connections with pipelining HTTP message format o There are two types, HTTP Request messages and HTTP response messages o HTTP Request Message First line is called the request line Has 3 fields: the method field, the URL field, and