Comsci Paper 2 - flashcards | Quizlet

Internet

- Interconnected set of networks and computers

- Permits transfer of data

- Permits delivery of services

- Data transfer governed by protocols (TCP/IP)

- Protocols and guidelines developed by W3C

World Wide Web (WWW)

- Set of hypertext-linked resources

- Resources identified by URIs (unique resource identifier)

- Transfers data between client and server via internet

- Resources can be read using a browser

Web 1.0

Consisted of read-only webpages made for information sharing; one-way content

Web 2.0

Consisted of read and write webpages in which people could interact, often used for social media; two-way content

Web 3.0

Consists of webpages that can read, write, and execute, designed for immersion; interconnected content

Hypertext

Text displayed with references (hyperlinks) to other text/files that the reader can immediately access, i.e. wikipedia.org links to Wikipedia's files

HTTP

Hypertext Transfer Protocol, governs transfer or exchange of hypertext. Protocol exists on the application layer

HTTPS

Hypertext Transfer Protocol Secure. Encrypts data wiht SSL or TLS to create a more secure form of HTTP

URL

Universal Resource Locator. Defines a pathway to a resource, i.e. web addresses. Consists of a protocol, domain name, directory, and file

Markup Language

Language that uses tags to annotate the information in a document for structuring, organization, and formatting

HTML

Hypertext Markup Language. Markup language for describing structure of a web page. May retrieve content with hyperlinks, and displays content sent over the internet

XML

Extensible Markup Language. A language for storing and transporting data. Extensible = easy addition of new information. Provides a common platform for sharing document information across applications.

XSLT

Extensible Stylesheet Language Transformations. Transforms XML into an output document, and contains template rules/instructions

JavaScript (JS)

Scripting language to add functionality to webpages. It is embedded into HTML along with CSS. Code is executed when page is download or an "event" (such as button press) is triggered, and allows dynamic web pages (changeable content without reload).

CSS

Cascading Style Sheets. Describes the visual presentation of a webpage, and is independent from HTML

DNS

Domain Name System. Part of the TCP/IP protocol, and translates text-based web addresses to numerical IP addresses, and vice versa.

TCP

Transmission Control Protocol. Receives packets of data from an application and divides it into segments, ready for IP. Establishes an initial connection.

IP

Internet Protocol. Delivers packets of data to the correct addresses. Defines the format of a packet, and includes routing information as a header in front of the TCP to tell where the packets should go.

TCP/IP

The set of protocols that governs the transfer of data over the Internet; TCP controls the retrieval, while IP controls the delivery.

FTP

File Transfer Protocol. Protocol for transferring files over a TCP based network.

Components of a Web Page

Header, Body, Footer, Navigation Bar, Banner, Hyperlinks, Sidebar

Meta tags

Information within the header that contains information about the webpage for search engines

Protocol

A set of rules to successfully carry out some process, i.e. TCP/IP for data transfer

Standards

Set of technical specifications that should be adhered to, to allow for functionality/safety/quality. Allows for interoperability (ability to exchange data) and accessibility (usable by as many people possible)

Search Engine

A program that searches for and identifies items in a database that correspond to keywords or characters specified by the user, used especially for finding particular sites on the World Wide Web

Web Crawler

AKA Web Spider/Web Robot. Browses the WWW and creates a copy of every web page it visits. It follows all the links of all the websites it visits (recursively), and indexes them, processing all their data and storing it in the search engine's database. It initially looks for robots.txt to know which links/pages to ignore.

Used by search engines to maintain real-time information by looking at metatags

SEO

Search Engine Optimization. Helps website to be better "crawled", or searched, by search engines

News Page

A website that provides relevant articles, audio and video on current news

Business Page

A website that is used to officially represent a brand on the Internet, and which is often used as the landing page for advertising content

Personal Page

A website created by an individual, or small group like a band, to contain content of a personal nature rather than content pertaining to a company, organization or institution

Blogs

Web log. A regularly updated website typically run by an individual or small group, that is written in an informal or conversational style on a particular topic

Forum

An online discussion site where people can hold conversations in the form of posted messages

Ecommerce Pages

Online portals that facilitate online transactions of goods and services through means of the transfer of information and funds over the Internet

Wiki

A website that allows collaborative editing of its content and structure by its users

Social Media

Forms of electronic communication (such as websites for social networking and microblogging) through which users create online communities to share information, ideas, personal messages, and other content (such as videos)

Static Webpage

Fixed webpage that does not change unless re-designed on the serverside. Allows no interaction nor any input

Dynamic webpage

Content may be changed by user or a program. Client-side scripting allows changes to be made in response to the user, and server-side scripting allows the page to produce different content depending on the user's profile/requests

PHP

Server-side scripting language, used to make dynamic and interactive web pages, mainly for data inputs.

MySQL

Database system used on the web to store data

Web Browser

Software application for retrieving, presenting, and traversing information resources on the World Wide Web

Browser Plugin

External program that runs within a web browser, usually to manage content that a browser is not designed to process

Client-Side Scripting

Scripts that run on the client device which allow changes in the webpage to be made in response to the user's actions, i.e. JS

Server-Side Scripting

Scripts that run on the server to produce different content depending on the user's profile/requests. Generally used to customize the content of a webpage for the user, i.e. personal customization, paywalls, etc.

Cookie

A piece of data from a website that is stored within a web browser that the website can retrieve at a later time

Server-Side Database

An organized collection of data stored on the server, often used to store user data

Server-Side XML

XML on the server-side, rather than storing user data, stores data for the features of the server and webpages

CGI

Common Gateway Interface. An interface which tells the webserver how to pass data to and from the database. It describes how the data in requests are transferred (inputted and outputted to and from databases/web browser)

CGI Scripts

Used to process a query (request) from the user and function as the glue between the query and the database

Surface Web

Pages that can be reached by search engine or links from other sites

Deep Web

Pages that can NOT be reached by search engine, considerably larger than surface web

Deep Web Content

Deep Web may include dynamically generated pages, password protected pages, or pages without inlinks such as academic databases or legal documents

Inlinks

Links from other pages/sites which link INTO a page

Outlinks

Links from a page which links OUT to another page

Algorithm

A process or set of rules to be followed in calculations or other problem-solving operations, especially by a computer

Google PageRank Algorithm

Importance of a webpage is determined by how many inlinks it has (other webpages linking/pointing to it). Other factors alongside this algorithm such as time the page has existed and frequency of search keywords determine what Google shows

Hubs

Page that contains large directories or compilations of links to authorities. The more high-authority pages it links to, the better the hub page/hub score

Authority

Page that contains information on specific topics. The more hubs linked to it, the better the authority page/authority score

HITS Algorithm

Hyperlink-Induced Topic Search. Search algorithm that ranks pages by the sum of their hub and authority score. Good hubs link to good authorities, and vice versa. Iterative/repetetive process, and thus relatively slow, and more susceptible to spamming

Web Scraper

Copies content from other sites to be used in other places. Allows the user to format said data to fit their needs

Meta Tags

Words inserted by the web designer which contains keywords/concepts for the web crawler to quickly understand what the page is about, and the description/title can be shown in search results

Web Crawler Types

Some web crawlers only focus on the metadata, while others will also include titles and subtitles, or sometimes even every single word on the page

Local/On Premises Hosting

Hosting a system onsite/at the business. Can be better for larger/more complex systems, more consistent, faster, and better security. However, higher costs as the business itself needs to maintain it

Remote/Cloud Hosting

Hosting a system offsite. Allows for better scalability and better outsourcing, and may be used anywhere, but likely to be less efficient than local hosting

IaaS

Infrastructure as a Service. Only thing being remotely hosted is the infrastructure required, such as servers and storage, while platform (OS+middleware) and software is hosted locally

PaaS

Platform as a Service. Remotely hosting the infrastructure and platform (OS+middleware), while software is hosted locally

SaaS

Software as a Service. Remotely hosting everything, from infrastructure to the platform and software, e.g. google docs

Distributed Systems

Type of network spread over multiple networks

Distributed Systems Function

Can distribute systems management, communication, and data processing, and network management software helps oversee systems/allow access. Allows for higher fault tolerance, stability, scalability, privacy, and data portability, but harder to maintain/manage

Mobile Computing

Also called nomadic computing. Use of portable computing devices and mobile communications technology, e.g. phones, laptops, tablets

Mobile Computing Features

Reduced size

- Light

- Portable

- Has batter power

- Lower power CPUs/processors

- SSDs

Ubiquitous Computing

Also called pervasive computing. Incorporation of scalable computing devices into daily life, e.g. IoT devices (fridges, speakers, etc.). Middleware is used to help connect systems

Ubiquitous Computing Features

- CPUs/processors embedded into everyday objects

- Uses wireless technology for connection

- Unobtrusive

- Devices can "talk" to each other

P2P Networks

Peer-to-Peer Networks. Network without distinctive clients and servers where individual nodes, or peers, both deliver and receive data, e.g. piracy

P2P Network Features

- Each computer may function as both server and client

- Used primarily for file sharing

- Often used to maintain user privacy

- May use a central server for coordination, but largely decentralized

Decentralized vs Centralized Network

Decentralized networks have no "main hub" for control, being distributed across nodes, while centralized networks have a single entity which controls the network

Grid Computing

Use of remote computers to act as a larger virtual unit, often used for data intensive problems

Grid Computing Features

- Distributed system with central control

- Geographically dispersed (computers in diff locations)

- Little/no communication between nodes

- "Virtual" supercomputer

- Highly scalable

- Uses standard computers

Node

Any device in a network that may act as a client, server, or both

Compression

Reducing a file's size by altering different properties of a file, encoding information using fewer bits than the original. Often done with images, audio, and video which typically take more storage. May be done with groups of files, e.g. ZIP

Compression Benefits

Reduces file size, saves network bandwidth, and higher performance when viewing/listening (since less data to load). However, may have reduced data quality (if lossy) and additional time is needed to compress+decompress

Lossy Compression

Some data removed to reduce size, higher compression ratio over lossless. Usually done when users won't notice, e.g. when resized down like a pfp

Lossless Compression

No loss of data, but lower compression ratio over lossy. Usually done when quality is needed, e.g. Marcell's ASA picture

Usability

A measure of how well a specific user in a specific context (i.e. non-disabled people) can use a product/design to achieve a defined goal effectively, efficiently and satisfactorily

Intuitive Design

Software designed to be simple and obvious to use and understand even without conscious reasoning, high degree of usability

Ergonomics

The scientific discipline which studies how humans interact with a system and its elements, to optimize both wellbeing and performance

Accessibility

Design of products, devices, services, or environments for people with disabilities or specific needs, with a goal of being inclusive. Different from usability

Key Usability Issues

- Difficult to handle hardware

- Difficult to understand software

- Complex UI

- Need to have prior knowledge

- Specialist support needed to use device

- No standards for similar devices

Examples to Improve Accessibility

1. Touchscreen

2. Voice recognition, e.g. Siri

3. TTS (Text-To-Speech)

4. Braille Keyboard

Common Usability Issues

- Hard to navigate

- Unclear instructions

- Layout/design complexity

- Not user friendly

Usability Issue Examples

Voice recognition - trouble with accents

Ticketing system - Unclear instructions, design complexity

Online payroll - Too many steps, not user friendly

Parallel Web Crawling

Simultaneously visiting multiple web pages using multiple threads or processes. Crucial for efficiently collecting and processing large amounts of data

Parralel Web Crawling Uses

Used in search engines, data mining, market research, and social media analysis with the goals of:

- Maximizing performance

- Minimizing overheads

- Avoiding duplication

- Communicate with each other

- Work across different geographical areas

Web Indexing

Method used to prioritize and/or organize the contents of a website, or the whole internet. Typically uses keywords and metadata for more practical/useful terms in searching the web

Search Engine Metrics

A standard of measurement used by search engines to help classify the quality of websites, such as popularity

White Hat SEO

Follows the guidelines given by search engines to improve website rankings, such as quality content and image descriptions

Black Hat SEO

Goes against search engine guidelines to improve website rankings, and can be illegal

Black Hat SEO Methods

- Duplicate content

- Keyword stuffing

- Link farming

- Hidden text

- Doorway pages

- Comment spamming/botting

- Scraping (plagiarism)

Search Issues

- Information overload (sifting relevant info may be difficult)

- Content quality (difficult to classify "high quality")

- Natural language processing (NLP, AI generated content)

- Multilingualism (Lots of content in different languages)

- Personalization (Users often want more customizable or personalized options)

- Privacy (History should be private)

Copyright

The exclusive right to publish and sell a work, protecting it form unauthorized duplication/selling

Copyleft

An approach which allows for the modification and distribution of a work (with limits)