Chapter 12: Networked Programs

Question 1

A Python library for parsing HTML documents and extracting data from HTML documents that compensates for most of the imperfections in the HTML that browsers generally ignore. You can download the code from www.crummy.com.

Answer 1

BeautifulSoup

Question 2

A number that generally indicates which application you are contacting when you make a socket connection to a server. As an example, web traffic usually uses ____ 80 while email traffic uses ____ 25.

Answer 2

port

Question 3

When a program pretends to be a web browser and retrieves a web page, then looks at the web page content. Often programs are following the links in one page to find the next page so they can traverse a network of pages or a social network.

Answer 3

scrape

Question 4

A network connection between two applications where the applications can send and receive data in either direction.
module must be imported

Answer 4

socket

import socket

Question 5

The act of a web search engine retrieving a page and then all the pages linked from a page and so on until they have nearly all of the pages on the Internet which they use to build their search index.

Answer 5

spider

Question 6

A set of precise and predetermined rules in hardware and software that determine how data is transmitted between different devices in the same network. Takes large scales processes and breaks them down into smaller functions so that devices can communicate.

Answer 6

protocol

Question 7

Internet protocol that defines how data is transmitted over the internet and determines how web servers and browsers should respond to commands.

data needs to be sent as bytes objects, not strings

Answer 7

HTTP(S)
hypertext transfer protocol (secure)

Question 8

syntax to signify EOL (end of line)
syntax to create blank line

Answer 8

\r\n (EOL)
\r\n\r\n (blank line)

Question 9

technique to receive data from socket in 512-character chunks and prints out data until no more to read (aka recv() returns empty string

Answer 9

while True:
data = mysock.recv(512)
if len(data) < 1:
break
print(data.decode(),end=’’)

Question 10

socket method to convert strings into bytes objects

Answer 10

.encode()

Question 11

socket method to convert bytes objects to strings

Answer 11

.decode()

Question 12

notation to convert strings to bytes objects

Answer 12

b’ ‘
eg. b’Hello World’

Question 13

method to set amount of time to wait before calling for more data in order to let the server catch up

Answer 13

time.sleep(0.25)
= wait 0.25 seconds between calls

import time

Question 14

The pausing of either the sending application or the receiving application

Answer 14

flow control

Question 15

python library that treats a web page like a file

Answer 15

urllib

import urllib.request

Question 16

command to open a web page with urllib
needs decode method

Answer 16

fhand = urllib.request.urlopen(filename)
for line in fhand:
print(line.decode().strip())

Question 17

urllib module that defines functions and classes which help in opening URLs

Answer 17

urllib.request

Question 18

urllib module that processes URL into components

Answer 18

urllib.parse

Question 19

urllib module that defines the exception classes for exceptions raised by urllib.request.

Answer 19

urllib.error

Question 20

opens a binary file for writing only

Answer 20

‘wb’

Question 21

module that allows program to access websites that strictly enforce HTTPS

Answer 21

ssl

import ssl

Question 22

file method that returns HTML source code as bytes object instead of returning an HTTPResponse object

Answer 22

.read()

Question 23

Unix/Linux commands used to retrieve web pages and remote files

Answer 23

curl
wget