World Wide Web PDF

World Wide Web Péter Jeszenszky Faculty of Informatics, University of Debrecen [email protected] Last modified: September 8, 2024  The Birth of the Web (1) The World Wide Web was born in CERN. Both the idea and the implementation...

World Wide Web Péter Jeszenszky Faculty of Informatics, University of Debrecen [email protected] Last modified: September 8, 2024  The Birth of the Web (1) The World Wide Web was born in CERN. Both the idea and the implementation came from Tim Berners- Lee (TBL). – For more information about TBL, see: https://www.w3.org/People/Berners-Lee/ The idea: – Tim Berners-Lee. Information Management: A Proposal. March 1989. https://www.w3.org/History/1989/proposal.html He recommended a hypertext information system to CERN. – Tim Berners-Lee, Robert Cailliau. WorldWideWeb: Proposal for a HyperText Project. 12 November 1990. https://www.w3.org/Proposal.html 2  The Birth of the Web (2) TBL is the creator of the following: – The first web server (CERN httpd) (December 24, 1990) https://www.w3.org/Daemon/ – The first web browser and HTML editor (WorldWideWeb) (December 25, 1990) https://www.w3.org/People/Berners-Lee/WorldWideWeb.html – HTML (HyperText Markup Language) https://info.cern.ch/hypertext/WWW/MarkUp/MarkUp.html – HTTP (HyperText Transfer Protocol) https://www.w3.org/Protocols/HTTP/AsImplemented.html – URI (Universal Resource Identifier), originally called as UDI (Universal Document Identifier) https://info.cern.ch/hypertext/WWW/Addressing/Addressing.html 3  The Birth of the Web (3) The first public website: http://info.cern.ch/ (launched on: August 6, 1991) – See: Restoring the first website https://first-website.web.cern.ch/first-website/ 4  History See: – http://www.storyoftheweb.org.uk/ – https://thehistoryoftheweb.com/ 5  Idea Originally, the idea of the Web is based on the following cornerstones: – Identifying resources by global identifiers (URIs) – Client-server model – Hypertext markup language (HTML) 6  Web Architecture Architecture of the Web from a contemporary viewpoint: – Architecture of the World Wide Web, Volume One (W3C Recommendation, 15 December 2004) https://www.w3.org/TR/webarch/ The client-server model is not mentioned at all in the text! 7  Web Architecture: Concepts (1) World Wide Web: an information space in which the items of interest (referred to as resources) are identified by URIs. Resource: anything that might be identified by a URI. – Information resource: a resource which has the property that all of its essential characteristics can be conveyed in a message. Uniform Resource Identifier (URI): a global identifier in the context of the Web. Representation: data that encodes information about resource state. 8  Web Architecture: Concepts (2) Content negotiation: offering multiple representations for a resource and selecting the one that is the most appropriate when a representation must be served. Dereferencing a URI: using a URI to access the referenced resource. – Access may take many forms, including retrieving, adding, or modifying a representation of the resource, and deleting some or all representations of the resource. 9  Web Architecture: Concepts (3) Web agent: a person or a piece of software acting on the Web on behalf of a person, entity, or process. – For example, a web crawler. User agent: one type of Web agent, a piece of software acting on behalf of a person. – For example, a web browser. 10  Architectural Bases of the Web Identification: – Resources are identified by global identifiers called URIs. Interaction: – Web agents communicate using standardized protocols that enable interaction through the exchange of messages. Web protocols include, for example, HTTP, HTTPS, and WebDAV. – A message may include data as well as metadata about a resource, the message data, and the message itself. Data Formats: – The choice of interaction protocol places limits on the formats of representation data and metadata that can be transmitted. – The Web itself does not constrain the data formats that can be used by content providers. For a data format to be usefully interoperable between two parties, the parties must agree (to a reasonable extent) about its syntax and semantics. 11  Web Architecture: Example Scenario URI http://weather.example.com/debrecen Ide nti fi es Resource Representation Debrecen Weather Report Metadata: Content-Type: application/xhtml+xml; charset=utf-8 ts en es Data: r ep R 10 Day Weather Forecast for Debrecen... 12  Standards (1) A standard is a document that provides requirements, specifications, guidelines or characteristics that can be used consistently to ensure that materials, products, processes and services are fit for their purpose. – See: https://web.archive.org/web/20200101101550/https: //www.iso.org/standards.html 13  Standards (2) By origin, there are three types of standards: – De facto standards: arise from common usage or market acceptance. Examples: the QWERTY keyboard layout, TeX, PDF (before 2008). – De jure standards: are mandated by regulators at the local, state, federal, and/or international level. Examples: International System of Units (SI), PDF (from 2008). – Voluntary consensus standards: are specified within a range of private institutions, including engineering societies, trade associations, accredited standards-setting organizations, and industry consortia. Examples: the Internet protocol suite (commonly known as TCP/IP), HTML, CSS. See: – Andrew L. Russell. Open Standards and the Digital Age. Cambridge University Press, 2014. https://arussell.org/open/ 14  Open Standard (1) There is no single, universally accepted definition: – OpenStand: The Modern Paradigm for Standards (IEEE, ISOC, IETF, IAB, W3C, …) https://open-stand.org/ – Open Standards Requirement for Software (Open Source Initiative) https://opensource.org/osr/ – … Further information: Open standard https://en.wikipedia.org/wiki/Open_standard 15  Open Standard (2) In general, an open standard is a standard that is freely available for use and adoption to anyone. Open standards are typically developed via a collaborative process. 16  Web Standards The following organizations are responsible for web standards: – Ecma International https://www.ecma-international.org/ – International Organization for Standardization (ISO) https://www.iso.org/ – Internet Engineering Task Force (IETF) https://www.ietf.org/ – Unicode Consortium https://unicode.org/consortium/consort.html – Web Hypertext Application Technology Working Group (WHATWG) https://whatwg.org/ – World Wide Web Consortium (W3C) https://www.w3.org/ – … 17  Internet Assigned Numbers Authority (IANA) Coordinates the allocation of codes and numbers that form the basis for the operation of the Internet. https://www.iana.org/ – Manages the DNS root zone, and the.int and.arpa domains. – Coordinates the allocation of IP addresses globally. – Maintains registries of codes and numbers used in a variety of Internet protocols. See: Protocol Registries https://www.iana.org/protocols IANA is a function that is currently performed by the Internet Corporation for Assigned Names and Numbers (ICANN), a not-for-profit corporation. 18  Internet Engineering Task Force (IETF) An international standards organization developing Internet standards. – For example, IETF develops the Internet protocol suite (commonly known as TCP/IP). – The IETF has no formal membership, no membership fee, participation is open to anyone. Mailing lists: https://www.ietf.org/list/ – The technical work is done in working groups. Formation: 1986 – See: IETF Turns 25 on 16 January 2011 https://www.ietf.org/mail-archive/web/ietf-announce/current/msg08366.html Publishes Internet standards-related specifications in the RFC series of documents. 19  Request for Comments (RFC) (1) The RFC series contains technical and organizational documents about the Internet. The RFC series of documents began in 1969 as part of ARPANET project. – The first RFC: Steve Crocker. Host Software. RFC 1, 7 April 1969. https://www.rfc-editor.org/info/rfc1 20  Request for Comments (RFC) (2) RFC Editor edits, publishes, and catalogs RFCs. https://www.rfc-editor.org/ By origin, the RFC series is split into four streams: – The Internet Engineering Task Force (IETF) Stream – The Internet Architecture Board (IAB) Stream – The Internet Research Task Force (IRTF) Stream – The Independent Submission Stream Further information about the RFC series: – Russ Housley (ed.), Leslie L. Daigle (ed.). The RFC Series and RFC Editor. RFC 8729, February 2020. https://www.rfc-editor.org/rfc/rfc8729 21  Request for Comments (RFC) (3) Each RFC is identified by a number, such as RFC 9110. Each RFC is available in ASCII text, such as: https://www.rfc-editor.org/rfc/rfc9110.txt – The same RFC in HTML: https://www.rfc-editor.org/rfc/rfc9110.html The list of all RFCs: https://www.rfc-editor.org/rfc-index.html 22  Request for Comments (RFC) (4) Published RFCs never change. Various errors are fixed by errata. Amendments can be also made by writing and publishing a revised RFC. – An RFC can obsolete or update earlier RFCs. 23  Request for Comments (RFC) (5) Example: Hypertext Transfer Protocol – HTTP/1.1 RFC 9112 RFC 9110 RFC 9111 RFC 7230 RFC 7231 RFC 7232 RFC 7233 RFC 7235 RFC 7234 RFC 2616 RFC 2068 24  Request for Comments (RFC) (6) The series of IETF RFCs contains the following two important sub-series: – Best Current Practice (BCP): BCPs document guidelines, processes, or the operation of the IETF itself. BCP Index: https://www.rfc-editor.org/rfc/bcp/ – Internet Standard (STD): STD Index: https://www.rfc-editor.org/rfc/std/ 25  Request for Comments (RFC) (7) BCPs and STDs are assigned a number in their subseries while retaining their RFC number. – Example: Scott O. Bradner. The Internet Standards Process – Revision 3. BCP 9, RFC 2026, October 1996. https://www.rfc-editor.org/rfc/rfc2026 Tim Berners-Lee, Roy T. Fielding, Larry Masinter. Uniform Resource Identifier (URI): Generic Syntax. STD 66, RFC 3986, January 2005. https://www.rfc-editor.org/rfc/rfc3986 Several RFCs may share the same BCP or STD number. – For example, an STD number identifies a standard not a document. 26 Request for Comments (RFC) (8) BCP 9: The Internet Standards Process RFC 5657 RFC 6410 Obsoleted Obsoleted by by RFC 1310 RFC 1602 RFC 2026 … Updated by RFC 8789 RFC 9282 27  Request for Comments (RFC) (9) Standards Track: the set of maturity levels of RFCs that are intended to become Internet Standards. – Originally, three maturity levels were used: Proposed Standard Draft Standard Internet Standard – Currently, the Proposed Standard and Internet Standard maturity levels are used. See: – Scott O. Bradner. The Internet Standards Process – Revision 3. BCP 9, RFC 2026, October 1996. https://www.rfc-editor.org/rfc/rfc2026 – Russell Housley, Dave Crocker, Eric W. Burger. Reducing the Standards Track to Two Maturity Levels. BCP 9, RFC 6410, October 2011. https://www.rfc-editor.org/rfc/rfc6410 28  Request for Comments (RFC) (10) Internet-Draft: a draft version of a specification made available for informal review and comment during the development. – May or may not eventually be published as an RFC. – Is subject to change or removal at any time. – Is valid for a maximum of six months. – Should not be cited or quoted in any formal document, except as “work in progress”. – Example: Austin Wright (ed.), Henry Andrews (ed.), Ben Hutton (ed.), Greg Dennis. JSON Schema: A Media Type for Describing JSON Documents. 10 June 2022. https://datatracker.ietf.org/doc/id/draft-bhutton-json-schema-01.html 29  Request for Comments (RFC) (11) On nearly every April 1 since 1989, one ore more funny RFCs has been published. – Example: Jogi Hofmueller (ed.), Aaron Bachmann (ed.), IOhannes Zmoelnig (ed.). The Transmission of IP Datagrams over the Semaphore Flag Signaling System (SFSS). RFC 4824, April 1 2007. https://www.rfc-editor.org/info/rfc4824 See: – April Fools' Day Request for Comments https://en.wikipedia.org/wiki/April_Fools%27_Day_Req uest_for_Comments 30 World Wide Web Consortium (W3C) The W3C is an international community where member organizations, a full-time staff, and the public work together to develop open web standards. – See: https://www.w3.org/about/ W3C publishes documents called Recommendations that define Web technologies and are considered Web standards. – See: https://www.w3.org/standards/ 31  W3C Design Principles Web for All: the Web must be available to all people, whatever their hardware, software, network infrastructure, native language, culture, geographical location, or physical or mental ability – Related concepts: web accessibility, internationalization Web on Everything: the Web must be accessible from a wide variety of devices. – E.g., mobile phones, smart phones, interactive television systems, domestic appliances, … See: – Our mission – Our design principles https://www.w3.org/mission/#principles – Vision for W3C https://www.w3.org/TR/w3c-vision/ 32  History of the W3C Was founded at MIT in October 1994. The director is Tim Berners-Lee, the inventor and creator of the Web. Has published more that 300 recommendations since 1996. – See: https://www.w3.org/TR/?status%5B0%5D=standard 33  W3C: A Few Milestones (1) October 1996: PNG (Portable Network Graphics) Specification Version 1.0 https://www.w3.org/TR/REC-png-961001 December 1996: Cascading Style Sheets, level 1 https://www.w3.org/TR/REC-CSS1-961217 February 1998: Extensible Markup Language (XML) 1.0 https://www.w3.org/TR/1998/REC-xml-19980210 April 1998: Mathematical Markup Language (MathML) 1.0 Specification https://www.w3.org/TR/1998/REC-MathML-19980407/ 34  W3C: A Few Milestones (2) October 1998: Document Object Model (DOM) Level 1 Specification https://www.w3.org/TR/REC-DOM-Level-1/ November 1999: XSL Transformations (XSLT) Version 1.0 https://www.w3.org/TR/1999/REC-xslt-19991116 December 1999: HTML 4.01 Specification https://www.w3.org/TR/html401/ January 2000: XHTML 1.0: The Extensible HyperText Markup Language https://www.w3.org/TR/2000/REC-xhtml1-20000126/ May 2001: XHTML 1.1 – Module-based XHTML https://www.w3.org/TR/2001/REC-xhtml11-20010531/ 35  W3C: A Few Milestones (3) October 2004: XML Schema https://www.w3.org/TR/xmlschema-0/ https://www.w3.org/TR/xmlschema-1/ https://www.w3.org/TR/xmlschema-2/ June 2011: Cascading Style Sheets Level 2 Revision 1 (CSS 2.1) Specification https://www.w3.org/TR/CSS2/ September 2011: Selectors Level 3 https://www.w3.org/TR/2011/REC-css3-selectors-20110929/ June 2012: Media Queries https://www.w3.org/TR/2012/REC-css3-mediaqueries-20120619/ October 2014: HTML5 – A vocabulary and associated APIs for HTML and XHTML https://www.w3.org/TR/2014/REC-html5-20141028/ 36  W3C: A Few Milestones (4) December 2019: WebAssembly Core Specification https://www.w3.org/TR/wasm-core-1/ April 2020: Web of Things (WoT) Architecture https://www.w3.org/TR/wot-architecture10/ January 2021: WebRTC 1.0: Real-Time Communication Between Browsers https://www.w3.org/TR/2021/REC-webrtc-20210126/ April 2022: Media Queries Level 3 https://www.w3.org/TR/mediaqueries-3/ May 2023: EPUB 3.3 https://www.w3.org/TR/epub-33/ August 2024: Geolocation https://www.w3.org/TR/geolocation/ 37  W3C Operation (1) Currently, W3C has 360 Members from around the world (September 8, 2024). – The list of members: https://www.w3.org/membership/list/ Adobe, Amazon, Apple, CERN, Google, IBM, Intel, Meta, Microsoft, SZTAKI, … Geographic or interest-based communities of individuals interested in W3C's activities: W3C Chapters https://chapters.w3.org/ – Hungary Chapter https://chapters.w3.org/hungary/ 38  W3C Operation (2) Development is carried out by working groups. Deliverables produced by working groups include technical reports, test suites, and open source software. Working groups are composed of experts in the area in question, each of whom can be any of the following: – a member of the W3C Team (e.g., a W3C employee), – an individual representing a member organization (typically, an employee of a member organization) – an individual participating as an invited expert. 39  W3C Operation (3) Currently, W3C has 43 working groups (September 8, 2024). https://www.w3.org/groups/wg/ – Cascading Style Sheets (CSS) Working Group https://www.w3.org/Style/CSS/members – HTML Working Group https://www.w3.org/groups/wg/htmlwg/ – Internationalization Working Group https://www.w3.org/International/i18n-activity/i18n-wg/ – Web Applications Working Group https://www.w3.org/groups/wg/webapps/ – Web Machine Learning Working Group https://www.w3.org/groups/wg/webmachinelearning/ – … 40  W3C Participation Participation is open to the public, you can: – Review specifications and provide feedback https://www.w3.org/standards/review/ – Join mailing lists https://www.w3.org/email/ – Join community and business groups https://www.w3.org/community/ – Contribute to W3C open source software https://www.w3.org/Status – Translate specifications and other resources https://www.w3.org/Consortium/Translation/ – Attend events (e.g., conferences, workshops) organized by W3C https://www.w3.org/events/ – … See: https://www.w3.org/get-involved/ 41  W3C Technical Reports See the following about the various technical reports published by W3C: – W3C Process Document (3 November 2023) https://www.w3.org/Consortium/Process/ – Types of documents W3C publishes https://www.w3.org/standards/types All technical reports: https://www.w3.org/TR/ W3C documents are licensed under the W3C Document License. – See: Document License https://www.w3.org/copyright/document-license/ – Further information: https://www.w3.org/copyright/ 42  Maturity Levels of W3C Technical Reports (1) Working draft (WD): a document that is published for review by the community (including W3C members), the public, and other technical organizations. – Some, but not all, Working Drafts are meant to advance to Recommendation. Candidate Recommendation (CR): a document that has already received wide review and is published to gather implementation experience. Proposed Recommendation (PR): a document that is of sufficient quality to become a Recommendation. Recommendation (REC): a Web standard suitable for wide adoption. Group Note (NOTE): a document that is not intended to be a formal standard. – Are published to document information other than technical specifications, such as use cases motivating a specification and best practices for its use. 43  Maturity Levels of W3C Technical Reports (2) A recommendation may become superseded,obsolete, or rescinded: – Superseded Recommendation: a specification that has been replaced by a newer version. Example: – XHTML 1.0 The Extensible HyperText Markup Language (Second Edition) https://www.w3.org/TR/xhtml1/ – Obsolete Recommendation: a specification that the W3C has determined lacks sufficient market relevance to continue recommending it for implementation. Example: – The 'view-mode' Media Feature https://www.w3.org/TR/view-mode/ – Rescinded Recommendation: a specification that W3C no longer endorses. 44  Maturity Levels of W3C Technical Reports (3) WD CR PR REC 45  WHATWG (1) Web Hypertext Application Technology Working Group (WHATWG) https://whatwg.org/ – A community committed to the evolution of the Web that develops standards implementable in web browsers. – Pronunciation: what-wee-gee, what-wig, what-double- you-gee Lásd: How do you spell and pronounce WHATWG? https://whatwg.org/faq#spell-and-pronounce – Further information: WHATWG – FAQ https://whatwg.org/faq 46  WHATWG (2) Standards: – DOM https://dom.spec.whatwg.org/ – Fullscreen API https://fullscreen.spec.whatwg.org/ – HTML https://html.spec.whatwg.org/ – URL https://url.spec.whatwg.org/ – WebSockets https://websockets.spec.whatwg.org/ – XMLHttpRequest https://xhr.spec.whatwg.org/ – … See: WHATWG – Standards https://spec.whatwg.org/ 47  WHATWG (3) History: – It was founded by programmers of Apple, the Mozilla Foundation, and Opera Software in 2004 who were concerned about the W3C’s activity related to the development of HTML. Operation: – Its operation is coordinated by the Steering Group whose current members are Apple, Google, Microsoft, and Mozilla. Participation: – Participation is open to the public. – See: WHATWG – Participation https://participate.whatwg.org/ 48  WHATWG (4) Development model: – The WHATWG develops specifications called “Living Standards” that are continuously updated. Living standards are licensed under the CC BY 4.0 license. https://creativecommons.org/licenses/by/4.0/ – See: WHATWG – Intellectual Property Rights Policy https://whatwg.org/ipr-policy 49  Size of the Web The total number of indexed web pages: > 4 billion. – See: https://www.worldwidewebsize.com/ The total number of web sites: > 1 billion. – See: Netcraft – August 2024 Web Server Survey https://www.netcraft.com/blog/august-2024-web-ser ver-survey/ 50  Wayback Machine (1) A service that allows people to visit archived versions of Web sites. – Website: https://archive.org/web/ – It makes the phrase “The internet doesn't forget” true. – A sub-project of the Internet Archive project launched in 1996. – Contains over 2 petabytes of data compressed, or 150+ billion web captures, including content from every top-level domain, 200+ million web sites, and over 40 languages. Further information: – https://help.archive.org/help/wayback-machine-general-information/ – https://help.archive.org/help/using-the-wayback-machine/ – https://blog.archive.org/2016/10/23/defining-web-pages-web-sites-and-web -captures/ 51  Wayback Machine (2) Collects web pages that are publicly available. When a dynamic page contains forms, JavaScript, or other elements that require interaction with the originating host, the archive will not contain the original site's functionality. 52  Wayback Machine (3) Example: – Snapshots saved for https://www.w3.org/: https://web.archive.org/web/*/https://www.w3.org/ – Snapshot saved on September 3, 2003 at 14:02:22: https://web.archive.org/web/20030903140222/https://www.w 3.org/ 53  Wayback Machine (4) A useful feature: Save Page Now – Capture a web page as it appears now for use as a trusted citation in the future. – Saves a specific web page one time only. 54