summary web programming introduction to web programming chapters (1)

internet

• Internet
• millions of computers connected together in some way
• example of devices ( phone lines , modems )
• they can share information.
• one big network of computers.
• The physical structure of the Internet uses
• fiber-optics cables, satellites, phone lines, and other telecommunications media that send data back and forth.
• internet → network of networks
• devices → PC - smart phones - modems - smart cars
• structure → wired - wireless
• the internet is
• content providers ( web pages ) → servers
• end users → client

www

• World Wide Web → a collection of electronic documents that are linked together like a spider web
• these documents are stored on computers called servers located around the world
• Web has evolved into
• a global electronic publishing medium
• and increasingly → a medium for conducting electronic commerce.
• website → static content - web application → dynamic content

web page

• web page → an electronic document written in a computer language called HTML (Hypertext Markup Language)
• Web pages can contain
• text, graphics, video, animation, sound
• as well as interactive features → such as data entry forms.
• examples of interactive features → entering data → users enter data ( as login pages )
• Each page has a unique address known as a URL (Uniform Resource Locator) → which identifies its location on the server.
• URL → is the path to access a certain web page → every webpage have a unique URL
• location of the URL → form the address bar

website

• website → is multiple web pages that are saved in directory's and sub directory's
• is there any limitation of web pages number ?
• yes → and the number of web pages depend on the storage space of the server
• A website → is one or more web pages that relate to a common theme, such as a person, business, organization, or a subject, such as sports.
• The first page is called the home page → which acts like an index, indicating the content on the site.
• From the home page → you can click hyperlinks to access other web pages.
• small summary’s
1. Webpage (home) is a specific page within a website; Website URL is the web address for the entire site.
• The website URL is usually the same as the home page, but if it's not, it could be the URL of another important page on the site.
2. A hyperlink is a clickable element on a webpage, and a URL specifies the web address.
3. "www" is a subdomain, and "http" ( hyper text transfer protocol ) or "https" are part of a URL.

• The development and maintenance of web pages → in order
1. plan a website → ( targets - recourse - goal - budget )
2. analyze and design a web site → the place where we put the security principles
• example : least privilege's - check user input - isolation
3. create a website
4. deploy a web site → deploy to let the website available to public
5. maintain a website → maintain is process of keeping a website up-to-date and running smoothly as well as performing optimally
• plan → analyze and design → create → deploy → maintain

• types of web sites
• Portal - News - Informational - Business/Marketing - Wiki - Online Social Network - Educational - Entertainment - Web Application - Personal

• Internet and web programming technologies are designed to be → portable
• portable → allowing you to design web pages and applications that run across an enormous range of Internet-enabled devices
• Client-side programming technologies → are used to build web pages and applications that are run on the client (in the browser on the user's device).
• Server-side programming → the applications that respond to requests from client-side web browsers, such as :
• searching the Internet - checking your bank-account balance - ordering a book from Amazon

HTML

• HTML (Hypertext Markup Language) → is a special type of computer language called a markup language designed to :
• specify the → content and structure of → web pages (also called documents) in a portable manner.
• HTML5, now under development → is the emerging version of HTML.
• HTML enables you to → create content that will render appropriately across the extraordinary range of devices connected to the Internet, including :
• smartphones, tablet computers, notebook computers, desktop computers, special-purpose devices such as large-screen displays at concert arenas and sports stadiums, and more.
• important for the exam → portable manner → run on multiple platforms OS ( Linux - iOS - etc. ) and devices
• browser → is the client → to see the webpages of a website

CSS

• Cascading Style Sheets (CSS) → are used to specify the presentation or styling of elements on a web page (fonts, spacing, sizes, colors, positioning).
• CSS was designed to style portable web pages independently of their content and structure.
• By separating page styling from page content and structure → you can easily change the look and feel of the pages on an entire website.
• CSS3 → is the current version of CSS under development.
• HTML5 → the structure - content of the website
• CSS → the styling - design - presentation of the webpage
• Cascading Style Sheets (CSS) is a simple mechanism for adding style (e.g., fonts, colors, spacing) to Web documents → one design will be imported to all the other pages not as HTML the require designing for each page
• example : I have 1000 pages → I want red color the update using CSS will be applied to all the pages at once - in HTML will be applied one by one
• Although HTML5 provides → some capabilities for controlling a document's presentation, it's better not to mix presentation with content.

JavaScript

• JavaScript → helps you build dynamic web pages (pages that can be modified "on the fly" in response to events → such as user input, time changes, and more) and computer applications.
• enables you to do the client-side programming of web applications.
• JavaScript was created by Netscape.
• JavaScript is a portable scripting language.
• Programs written in JavaScript can run in web browsers across a wide range of devices.
• JavaScript → interactive website ( entre values - retrieve values ) - dynamic web pages

W3C

• World Wide Web Consortium (W3C) was founded → In October 1994
• Goal of W3C → is to make the Web universally accessible regardless of disability, language, culture.
• W3C → Standardization Organization.
• Web technologies standardized by W3C are called → Recommendations.
• Recommendations include → Hypertext Markup Language 5 (HTML5), Cascading Style Sheets 3 (CSS3), and the Extensible Markup Language (XML).
• W3C → responsible for → HTML - CSS - XML
• to be more compatible between between nations and devices
• Extensible Markup Language (XML) lets you define and store data in a shareable manner. XML supports information exchange between computer systems such as websites, databases, and third-party applications. → tags
• CSV (comma-separated values) file is a text file that has a specific format which allows data to be saved in a table structured format. → comma

• what is the needed for the web
• personal computer.
• Web browser → software to access the Web.
• connection → to an Internet service provider (ISP).
• Servers → to host the data.
• Routers and switches → to direct the flow of data.

• There are three main ways to move between web pages or websites:
• Clicking a text hyperlink.
• Clicking a hyperlinked graphic image → such as a button, photograph, or drawing.
• Typing the URL of a web page in the location box (also known as → the address field) of your web browser and then pressing the Enter or Return key.

• how the web pages works
• Web pages are stored on web servers located around the globe.
• Entering the (Uniform Resource Locator) URL of a web page in your web browser or clicking a link sends a request to the server which hosts the page.
• The server sends the web page to your computer, and your web browser displays it on your screen.

• The Web is a client/server application → Web browsers are → clients which send requests to Web servers → which send responses back.
• Different browsers → Microsoft Internet Explorer, Netscape, lynx (UNIX).
• Although browsers share a common set of features, each browser might render pages differently.
• browser is a client that will request the content
• browser use client-server communication
• note: Peer-to-Peer (P2P) Service? A peer-to-peer (P2P) service is a decentralized platform whereby two individuals interact directly with each other, without intermediation by a third party

URL

• Uniform Resource Locators (URLs) are used to identify Web pages → basically a URL is a web address.
• URLs have 3 components:
• A Prefix → (usually http://) → data transfer protocol → required to request to the server
• A Hostname → (such as www.cityu.edu.hk) → identify the computer in the internet
• A Path → (such as /scm/index.htm) → identify the file in hierarchal directory structure on the server

IP - DNS

• Every computer connected to the Internet must have a → unique IP address, no matter whether → it's a client or a server (or both).
• An IP address → is just a number that identifies a host on the Internet.
• Example: 212.171.218.34 or 144.214.5.218
• The Domain Name System (DNS) → is a database that matches IP addresses to host names.
• the Domain Name System (DNS) translates host names into IP addresses, which are then used by TCP to establish connections between HTTP clients and servers.
• Domain names are administered in such a way that they are guaranteed to be unique.
• Domain names are organized in a → hierarchical structure.

top - second - third level domain

• www.apple.com
• Top-level domain → country domains → important for exam
• .com - Commercial, .net - Network, .gov - Government, .edu - Education, .co - Company, .jo - Jordan, .us - United States, .uk - United Kingdom, .ca - Canada, .au - Australia, .de - Germany.
• .com → generic Top level domain gTDL
• second level domain → actual name of the organization or service → contains : letter - 0 to 9 - dashes ( - ) → apple
• third level domain → strings of character that designate different hosts within second level domain or services
• www → core - main website
• sweb.cityu.edu.hk → sweb → sub network within the cityu

TCP / IP

• TCP → transitions Control Protocol
• Messages are sent → are made up of packets which include sender IP and destination IP.
• IP address internet protocol → every machine has a unique IP address.
• FTP: File transfer protocol
• SMTP: simple mail transfer protocol
• NNTP: network news transfer protocol
• HTTP: Hypertext Transfer protocol