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