HTTP, HTTPS, HTML, URL, XML, XSLT, CSS

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Web Science[1]


Characteristics of the web[edit]

You must memorize this content. You should be able to recognize these acronyms and identify the characteristics of each.


HTTP Definition[edit]

The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, and hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web.[2].

HTTP Characteristics[edit]

  • HTTP is an application-layer protocol
  • HTTP functions as a request–response protocol [4]
  • HTTP is the protocol to exchange or transfer hypertext [5]
  • HTTP is stateless - Each transaction between the client and server is independent and no state is set based on a previous transaction or condition.[6]
  • HTTP Uses requests from the client to the server and responses from the server to the client for sending and receiving data. [7]
  • HTTP utilizes headers at the start of each message.[8]

HTTPS Definition[edit]

HTTPS (also called HTTP over TLS, HTTP over SSL, and HTTP Secure) is a protocol for secure communication over a computer network which is widely used on the Internet. HTTPS consists of communication over Hypertext Transfer Protocol (HTTP) within a connection encrypted by Transport Layer Security, or its predecessor, Secure Sockets Layer. The main motivation for HTTPS is authentication of the visited website and protection of the privacy and integrity of the exchanged data.[9]

HTTPS Characteristics[edit]

  • HTTPS URLs begin with "https://" and use port 443 by default, whereas HTTP URLs begin with "http://" and use port 80 by default
  • HTTPS encrypts the request and response. If you were to snoop (or spy) on the network data, you would only (theoretically) see the origin and destination IP and port numbers
  • HTTPS piggybacks (or rides) on top of HTTP

HTML Definition[edit]

HyperText Markup Language, commonly referred to as HTML, is the standard markup language used to create web pages[10]. Please see our wiki page on HTML for a deeper discussion of HTML.

HTML Characteristics[edit]

  • HTML is a markup language. A markup language is a system for annotating a document in a way that is syntactically distinguishable from the text [11]
  • HTML markup consists of several key components, including those called tags (and their attributes), character-based data types, character references and entity references.[12]
  • HTML tags most commonly come in pairs although some represent empty elements and so are unpaired. [13]
  • The first tag in such a pair is the start tag, and the second is the end tag (they are also called opening tags and closing tags).[14]

URL Definition[edit]

A Uniform Resource Locator (URL), is a reference to a web resource that specifies its location on a computer network and a mechanism for retrieving it. A URL is a specific type of Uniform Resource Identifier (URI).[15]

URL Characteristics[edit]

  • URL's have different parts. Every URL MUST have:
    • scheme and host
  • URL's have different parts. Every URL MIGHT have:
    • user information
    • port
    • query
    • fragment

Please click here for an example of these different parts. In your normal day-to-day use, you probably only use a scheme and a host.

XML Definition[edit]

In computing, Extensible Markup Language (XML) is a markup language that defines a set of rules for encoding documents in a format that is both human-readable and machine-readable.[16]

XML Characteristics[edit]

  • XML consists mostly of markup and content[17]
    • Generally, strings that constitute markup either begin with the character < and end with a > [18]
    • The text between the markup is the content[19]
  • XML has tags.
    • A tag is a markup construct that begins with < and ends with >. Tags come in three flavors, start tag, end tag, and empty-element tag[20]
  • XML may have a declaration that describes some information about themselves.[21]

XSLT Definition[edit]

XSLT (Extensible Stylesheet Language Transformations) is a language for transforming XML documents into other XML documents or other formats such as HTML for web pages, plain text or XSL Formatting Objects, which may subsequently be converted to other formats, such as PDF, PostScript and PNG. XSLT 1.0 is widely supported in modern web browsers. [22]

XSLT Characteristics[edit]

CSS Definition[edit]

Cascading Style Sheets (CSS) is a style sheet language used for describing the presentation of a document written in a markup language. CSS is designed primarily to enable the separation of document content from document presentation, including aspects such as the layout, colors, and fonts. This separation can improve content accessibility, provide more flexibility and control in the specification of presentation characteristics, enable multiple HTML pages to share formatting by specifying the relevant CSS in a separate .css file, and reduce complexity and repetition in the structural content. [23]

CSS Characteristics[edit]

  • CSS has selectors. Selectors declare which part of the markup a style applies to by matching tags and attributes in the markup itself.[24]
  • CSS has declaration block. A declaration block consists of a list of declarations in braces. Each declaration itself consists of a property, a colon (:), and a value.[25]
  • CSS has specificity. Specificity refers to the relative weights of various rules. It determines which styles apply to an element when more than one rule could apply.[26]
  • CSS has inheritance. Inheritance is a key feature in CSS; it relies on the ancestor-descendant relationship to operate. Inheritance is the mechanism by which properties are applied not only to a specified element, but also to its descendants[27]

Do you understand this?[edit]

You must simply memorize these. There isn't anything fancy about this. If you need help memorizing, please use a mnemonic strategy.

Standards[edit]

These standards are used from the IB Computer Science Subject Guide[28]

  • Identify the characteristics of the following: HTTP, HTTPS, HTML, URL, XML, XSLT, CSS.

References[edit]

  1. ↑ http://www.flaticon.com/
  2. ↑ https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol
  3. ↑ https://www.lsr.com/white-papers/the-power-of-802-15-4-and-ethernet
  4. ↑ https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol
  5. ↑ https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol
  6. ↑ http://www.comptechdoc.org/independent/web/http/reference/httprfccopy.html
  7. ↑ http://www.comptechdoc.org/independent/web/http/reference/
  8. ↑ http://www.comptechdoc.org/independent/web/http/reference/
  9. ↑ https://en.wikipedia.org/wiki/HTTPS
  10. ↑ https://en.wikipedia.org/wiki/HTML
  11. ↑ https://en.wikipedia.org/wiki/Markup_language
  12. ↑ https://en.wikipedia.org/wiki/HTML#Markup
  13. ↑ https://en.wikipedia.org/wiki/HTML#Markup
  14. ↑ https://en.wikipedia.org/wiki/HTML#Markup
  15. ↑ https://en.wikipedia.org/wiki/URL
  16. ↑ https://en.wikipedia.org/wiki/XML
  17. ↑ https://en.wikipedia.org/wiki/XML
  18. ↑ https://en.wikipedia.org/wiki/XML
  19. ↑ https://en.wikipedia.org/wiki/XML
  20. ↑ https://en.wikipedia.org/wiki/XML
  21. ↑ https://en.wikipedia.org/wiki/XML
  22. ↑ https://en.wikipedia.org/wiki/XSLT
  23. ↑ https://en.wikipedia.org/wiki/Cascading_Style_Sheets
  24. ↑ https://en.wikipedia.org/wiki/Cascading_Style_Sheets
  25. ↑ https://en.wikipedia.org/wiki/Cascading_Style_Sheets
  26. ↑ https://en.wikipedia.org/wiki/Cascading_Style_Sheets
  27. ↑ https://en.wikipedia.org/wiki/Cascading_Style_Sheets
  28. ↑ IB Diploma Programme Computer science guide (first examinations 2014). Cardiff, Wales, United Kingdom: International Baccalaureate Organization. January 2012.

Provide an answer from a number of possibilities. Recognize and state briefly a distinguishing fact or feature.

Give a specific name, value or other brief answer without explanation or calculation.

a group or system of interconnected people or things.

Develop information in a diagrammatic or logical form.

Give a sequence of brief answers with no explanation.

Use an idea, equation, principle, theory or law in relation to a given problem or issue.

Provide an answer from a number of possibilities. Recognize and state briefly a distinguishing fact or feature.

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