end of CH 2 questions

Question 1

What are the different types of application architectures?

Answer 1

Host-based (all processing done on host system and all data on host with terminals providing access),

client-based (with processing done on client and all data stored on server),

and client-server (balanced processing; usually host provides data access and storage while the client provides application and presentation logic).

Question 2

Describe the four basic functions of an application software package.

Answer 2

Data storage, data access logic, application logic, and presentation logic.

Question 3

What are the ADVANTAGES of host-based networks?

Answer 3

• Centralized security
• Integrated architecture from single vendor
• Simpler, centralized installation

Question 4

What are the DISADVANTAGES of host-based networks?

Answer 4

• Having all processing on host may lead to overload
• Cost of software and upgrades; expensive infrastructure
• Terminal totally dependent on server

Question 5

What are the ADVANTAGES of client-server networks

Answer 5

• Balanced processing demands
• Lower cost; inexpensive infrastructure
• Can use software and hardware from different vendors
• Scalability

Question 6

What are the DISADVANTAGES of client-server networks?

Answer 6

Problems with using software and/or hardware from different vendors
-More complex installation or updating (although automated installation software helps greatly in this area).

Question 7

What is middleware and what does it do?

Answer 7

Middleware manages client-server message transfer and shields application software from impacts of hardware changes.

Middleware provides standard communication between products of different vendors through translation.

Question 8

Suppose your organization was contemplating switching from a host-based architecture to client-server. What problems would you foresee?

Answer 8

There may be somewhat greater complexity of upgrades, although newer software is reducing the impact of this kind of problem.

Question 9

Which is less expensive: host-based networks or client-server networks? Explain.

Answer 9

Client-server networks are less expensive because in a competitive market involving multiple vendors, software and hardware upgrades cost substantially less.

Question 10

Compare and contrast two-tiered, three-tiered, and n-tiered client server architectures. What are the technical differences, and what advantages and disadvantages do each offer?

Answer 10

Three-tiered architectures typical separate (1) presentation logic, (2) application logic, and (3) and data access logic and storage.
———-
In n-tiered architecture more than one tier may be used to support application logic, typically due to a Web server tier being included.
———-
Three-tiered or n-tiered architectures place a greater load on the network, but balances server load better and is more scalable.

Question 11

How does a thin client differ from a thick client?

Answer 11

Thick clients support all or most application logic while thin clients support little or no application logic.

Question 12

What are the benefits of cloud computing?

Answer 12

Benefits include gaining access to experts to manage the cloud, potentially lower costs, scalability, and pay-as-you-go.

Question 13

What is a network computer?

Answer 13

A network computer supports Internet access but has no hard disk local storage.

Question 14

For what is HTTP used?

Answer 14

n HTTP request from a Web browser to a Web server has three parts. Only the first two part is required; the last is optional.

Question 15

What are HTTP’s major parts? (part 1)

Answer 15

1. the request line, provides the URL, and ends with the HTTP version number that the browser understands.

Question 16

What are HTTP’s major parts? (part 2)

Answer 16

2. the request header, which contains a variety of optional information such as the Web browser being used the date, and a user id and password for use if the Web page is password-protected.

Question 17

What are HTTP’s major parts? (part 3)

Answer 17

3. the request body, which contains information sent to the server, such as information from a form.

Question 18

For what is HTML used?

Answer 18

HTML is the language in which web pages are created

Question 19

Describe how a Web browser and Web server work together to send a Web page to a user.

Answer 19

In order for the requests from the Web browser to be understood by the Web server, they must use the same standard protocol (HTTP)

Question 20

Describe how mail user agents and message transfer agents work together to transfer mail messages.

Answer 20

user sends the message (transfer agent) > agents read envelope > send message though network > arrives in the receiver’s mail box

Question 21

What roles do SMTP, play in sending and receiving e-mail on the Internet?

Question 22

What roles do POP play in sending and receiving e-mail on the Internet?

Answer 22

A different standard called Post Office Protocol (POP) defines how user agents operate and how messages to and from mail transfer agents are formatted.

Question 23

What roles do IMAP play in sending and receiving e-mail on the Internet?

Answer 23

With IMAP, e-mail messages can remain stored on the mail server after they are read.

Question 24

What are the major parts of an e-mail message?

Answer 24

body, which is the message itself.

Question 25

What is a virtual server?

Answer 25

A virtual server is one computer that acts as several servers.

Question 26

What is Telnet, and why is it useful?

Answer 26

Telnet enables users on one computer to login into other computers on the Internet. ------- Telnet can be useful because it enables access to servers or host computers without sitting at the dedicated computer’s keyboard.

Question 27

What is cloud computing?

Answer 27

With cloud computing, a company contracts with another firm to provide software services over the Internet, rather than installing the software on its own servers.

Question 28

Explain how instant messaging works.

Answer 28

An instant messaging (client) communicates with an IM server application.

Question 29

Compare and contrast the application architecture for videoconferencing with the architecture for e-mail.

Answer 29

Videoconferencing must deliver real-time services demanding high capacity data transfer for both image and voice transmission. ------ E-mail messages (typically without large attachments) are relatively small by comparison, can be received by any Internet-capable computer, and do not have to be consumed in real time.

Question 30

Which of the common application architectures for e-mail (two-tier client-server, Web-based) is "best"? Explain.

Answer 30

if a person wants to be able to access their e-mail from anywhere, then Web-based is best. ---------- If the person wants professional backup and storage within an organization, then two-tier client-server is best. -------- If the person wants storage of e-mail strictly under their control and they also want to be able to access their e-mail files off-line when there is a network service interruption, then host-based is best.

Question 31

Some experts argue that thin-client client-server architectures are really host-based architectures in disguise and suffer from the same old problems. Do you agree? Explain.

Answer 31

the two approaches are similar, but not exact, from a technological design perspective.