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Flashcards in Chapter 2 Deck (45):
1

What is a network application?

-The software packages that run in the applicationlayer.

2

What is an application architecture?

-The way in which the functions of the application layer software are spread among the clients and servers in the network.

3

What are the four general functions of the work done by an application program?

-Data storage
-data access logic
-application logic
-presentation logic

4

Describe data storage.

-programs require data to be stored and retrieved.

5

Describe data access logic.

-the processing required to access data such as database queries(SQL)

6

Describe application logic.

-business logic, simple or complex depending on the application

7

Presentation logic.

-the presentation of information to the user and the acceptance of the user's commands.

8

What are the four fundamental application architectures?

-host-based architectures
-client-based architectures
-client-server architectures
-peer-to-peer architectures.

9

Describe host-based architecture.

-A server or large mainframe performs all four functions.

10

What are two problems with host based architectures?

-server must process all messages. Server can become overloaded.
-can't prioritize, slow response time.
-lumpy upgrades

11

Describe client based architecture.

-client and server are both personal computers.
-client responsible for presentation, application, and data access logic.
-server responsible for data storage

12

What is a drawback to the client based architecture?

-all data on server must transfer to client for processing.
-can overload network circuits.

13

Describe client-server architectures.

-balance the processing between the client and the server by having both do some of the logic.
-client responsible for presentation logic
-server responsible for data access logic and data storage.
-application logic can reside on both or be split between both.

14

What is a strength and disadvantage of the client-server architecture?

-software and hardware from different vendors can be used but it's hard to get them to work together and you need middleware.

15

What is middleware?

-software that sits between the application software on the client and the application software on the server.

16

What two things does middleware do?

-provides standard way of communicating that can translate between software from different vendors.
-manage message transfer from clients to servers

17

Describe a two-tier architecture?

-only uses one set of clients and one set of servers.

18

Describe a three-tier architecture

-uses three sets of computers.
-Client: presentation logic.
-server: application logic
-server: data access logic and data storage.

19

Describe a n-tier architecture

-client responsible for presentation logic.
-database server responsible for data access logic and data storage.
-application logic is spread across two or more different sets of servers.

20

What is an advantage of an n-tier architecture?

-separates processing that occurs to better balance the load on the different servers.
-is more scalable.

21

What are the disadvantages to an n-tier architecture?

-puts a greater load on the network.
-much more difficult to program and test software.

22

Describe a thin-client.

-little or no application on the client.

23

Describe a thick-client.

-places all or almost all of the application logic on the client.

24

Describe the distributed computing model.

-application systems use web browser as client software with java javascriptor AJAX downloaded as needed.

25

Describe a peer-to-peer architecture.

-all computers act as both a client and a server.
-all clients perform all four function

26

What is scalability?

-the ability to increase or decrease the capacity of the servers to meet changing needs.

27

Describe the benefits of the client-server architecture.

-more scalable
-more reliable
-the cheapest.
-enables cloud computing

28

What is server virtualization?

-the opposite of scaling.
-install many virtual or logical servers on the same physical computer.

29

What is green computing?

-environmentally sustainable computing.

30

What is HTTP?

-the standard protocol for communication between a web broser and a web server.

31

What is a HTTP request?

-special packet that contains URL and other information

32

What is an HTTP response?

-response or error message from server.

33

What are the three parts of an HTTP request?

-request line: starts with command "get", provides web page, ends with HTTP version number.
-request header: variety of option info(browser used and date)
-request body(info user has typed)

34

What are the three parts of the HTTP response?

-response status: http version number and status code
-response header: web server, date, and exact URL
-response body: web page

35

Describe SMTP

-Simple Mail transfer protocol: most commonly used email standard
-implemented as a two-tier thick client-server application.

36

Describe a two-tier email architecture.

-each client computer runs an application layer software package called a mail user agent(email client)
-user agent sends SMTP packet to a mail server running a mail transfer agent software packet.
-covers transmission between mail servers.

37

What do POP and IMAP do?

-get mail between receiver's email client and his or her mail server.

38

Describe POP.

-before email can be read, must be copied to clients hard disk and deleted from server.

39

Describe IMAP.

-email messages can remain stored on the mail server after they are read.

40

Describe a three-tier thin client-server email architecture.

-uses web server and web browser to provide access to your email.(web-based email).
-browser sends form information inside http request.
-server takes http request, builds SMTP packet, sends HTTP response back to client, sends SMTP packet to mail server
-mail server processes SMTP packet as though it came from a client computer.

41

Describe an SMTP packet.

-heasder: source and destination email address, date, subject
-body: word DATA followed by the message.
-

42

What does MIME software do?

-Multipurpose Internet Mail Extension.
-takes nontext files and translates each byte into a special code that looks like regular text.

43

Describe telnet.

-enables users to log in to servers.
-uses account name and password of an authorized user to log in.
-keystrokes sent over in plain text.

44

What is videoconferencing?

-provides real-time transmission of video and audio signals to enable people in two or more locations to have a meeting.

45

What is webacsting

-one-directional videoconferencing.