chapter 2

Question 1

what is the network applications

Answer 1

these are the software packages that run in the application layer

Question 2

Application architecture

Answer 2

It is the way in which the functions of the application layer software are spread among the clients and servers in the network.
              5 general functions:
1 Data storage 
2 data access logic 
3 application logic
4 presentation logic 
5 services logic

Question 3

Four fundamental application architectures

Answer 3

1 host-based architecture = the server (or a host computer) performs virtually all the work.
2 In client-based architectures = the client computers perform most of the work.
3 client-server architectures = the work is shared between the servers and clients
4 cloud-based architectures = the cloud provides services to the client.

Question 4

Cloud Computing deployment models

Answer 4

Private Cloud = by one company
Public cloud = multiple organizations that share the same cloud resources
community cloud = organizations that have a common purpose. It is the subset of public cloud

Question 5

Host based architectures

Answer 5

The server performs all functions:
Problem: 1 server must process all messages
2 High cost to upgrade `

So the server has: 
1 Presentation logic 
2 services logic 
3 application logic 
4 data access logic 
5 data storage

Question 6

Client based architectures

Answer 6

• Client are personal computers on a LAN
• the server is usually another personal computer on the same network.
  Problem = all the data on the server must travel to the client for processing.
  Client (personal computer)
• Presentation logic
• application logic
• data access logic
  Server (personal computer)
• data storage

Question 7

Middleware

Answer 7

• The advantage of the client-server is that they enable software and hardware from different vendors to be used together
• (middleware )This software sits between the application software on the client and application software on the server

Question 8

Middleware standards

Answer 8

Two most important:
1 Distributed computing environment
2 Common object request broker architecture.

Question 9

two-tier architectures

check this one this might be wrong

Answer 9

server
1 Presentation logic
2 application logic  
3 Data access logic 
server 
data storage

Question 10

Three-tier architectures

Answer 10

uses three sets of computers
- client 
   presentation logic 
- application server 
    service logic and application logic 
-  server 
    data access logic 
    data storage

Question 11

n-tier architectures

Answer 11

Client-server
- Presentation logic 
database server
- data access logic 
- data storage 
web-server 
- application logic 
application server 
- services logic 
 - application logic

ADvantage
It balances the load between different servers in a better way.

Two primary disadvantages

• it puts greater load on the network
• difficult to program and test software in n-tier architectures that in two-tier architectures

Question 12

thin client and thick client

Answer 12

• places little or no application logic on the client

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

Question 13

Cloud Computing architectures

Answer 13

they outsource part or all of the infrastructure to other firms
– Three common cloud-based architecture models that an organization can pick from.
1 infrastructure as a service
2 platform as a service
3 software as a service

Question 14

Software as a Service (SAAS)

Answer 14

With this the organization outsource the entire application to the cloud.
SaaS is based on multitenancy = This means that having copies of the same application, only one application that everybody shares, but people can customize it for hir of her needs

CRM is another SaaS

Question 15

Platform as a Service

Answer 15

You can build your own application and manage your own data on the cloud infrastructure provided by your cloud supplier.
Hardware and software infrastructure is rented from the cloud provider

Question 16

Infrastructure as a service

Answer 16

Cloud provider manages the hardware, including servers, storage, and networking components
The organization is responsible for all the software, including operating system , database software, and its applications and data.

Question 17

Peer to peer

Answer 17

All computers performs all four functions
data can be installed on the network
challenge is finding the data
security is a major concern in the most p2p networks

Question 18

How the web works

Answer 18

1 it is a two-tier client-server architecture
2 each client computer needs a web browser
3 each server on a network needs a web server
4 to get a page on a web, the user must type the
Internet uniform resource locator (URL)
for the page they want.
5 The protocol for communication between a web browser and a web server is Hypertext Transfer Protocol (HTTP)
6 Web browser issues a special packet called an HTTP request that contains the URL and other information about the web page requested
7 The server processes it and sends back an HTTP response

Question 19

Inside an HTTP request

Answer 19

an HTTP reuqest from a web browser to a web server has three parts
the first two are required but the last is optional
1` the request line
2 request line
3 request body

Question 20

Inside an HTTP response

Answer 20

Response status = it contains http version number the server has used, a status code, and a reason phrase.
Response header = a variety of optional information, such as the web server being used, the date and the exact URL of the page in the response
response body = which is the web page itself