Chapter 20

Chapter 19

1.	What is a computer network? What is the primary purpose of a computer network?
2.	Describe the two types of computer networking environments.
3.	Describe the purpose of the TCP/IP Internet networking protocols.
4.	What’s the difference between the terms server and server application? Client and client application?
5.	Describe the relationship between a server application and client application.
6.	List and describe at least two ways network applications can be distributed?
7.	What term is used to describe a server application that can handle multiple simultaneous client connections?
8.	What term is used to describe a network application logically divided into more than one functional layer? List and describe the purpose of three possible functional layers.
9.	List and describe the purpose of the layers of the Internet protocol stack. Describe how data is transmitted from one computer to another via the Internet protocols.
10.	What’s the difference between TCP and UDP?
11.	What services does IP provide?
12.	Describe a client-server network application connection scenario. Focus on the purpose and use of the classes ServerSocket, Socket, and the I/O stream classes InputStream & OutputStream.
13.	In what way does the URL class simplify network programming?
14.	Describe in general terms how Java’s Remote Method Invocation (RMI) works.

Answers

1.	- The primary purpose of a computer network is resource sharing. A resource can be physical (i.e. a printer or a computer) or metaphysical (i.e. knowledge or data).
2.	- homogeneous; heterogeneous
3.	- Transmission Control Protocol (TCP) and Internet Protocol (IP) — collectively referred to as TCP/IP, have emerged as the standard network protocols through which different types of computers can talk to each other.
4.	- The term server refers to the hardware on which a server application (software) runs; The term client refers to the hardware on which a client application (software) runs.
5.	- A server application provides one or more services to a client application.
6.	- Logically and physically
7.	- multithreaded
8.	- multitiered (or multilayered); data access tier, mission tier, presentation tier
9.	- Application layer, transport layer, network layer, data link and physical layers
10.	- TCP guarantees packet delivery whereas UDP does not
11.	- The Internet Protocol (IP) is a connectionless service that permits the exchange of data between hosts without a prior call setup.
12.	- a Socket object is used to connect to a ServerSocket object which is listening on a specified host and port. When the ServerSocket object detects an incoming client connection the accept() method will return a Socket object that can be used to communicate between server and client applications.
13.	- It hides the messy details of socket programming.
14.	- An RMI service is created and registered to run on a server via the RMI registry. Stub classes are generated for the service and deployed with the client. The client gets a reference to the remote object using the Naming.lookup() method.