World Wide WebShort history of WWW application Using WWWFunctioning principles of WWWURL System Creating Web pages HTML languageHTML Editors

World Wide Weba hardware & software context which ensures user-friendly access to information stored on thousands of Internet web serversThe most popular Internet information applicationuser-friendly interface ensures obtaining a large amount of information in an expressive form & in a short amount of time

World Wide Web short historyWeb evolved from an application used for displaying results of particle physics experiments appeared in 1989 at CERN, Geneva - Tim Berners Leeaim to ensure efficient network sharing of experimental resultsfirst prototype presented at Hypertex91 Conference (December), San Antonio, TexasFebruary 1993 - first graphical interface - Mosaic - NCSA (National Center for Supercomputer Applications)

World Wide Web - evolutionMarc Andersen founded Netscape Communications Inc., dedicated to developing Web software - Netscape NavigatorNetscape became a public company in 1995 (1.5 billion dollars)1994: CERN & MIT form the WWW consortium, aiming at developing the Webprotocol standardization, site compatibility Address: http://www.w3.org

Using WWWWeb - a collection of information spread on web servers, structured in pages & sitespages may contain links to other pages - hypertexts, hyperlinksclick on a hyperlink the associated is page is loaded (transferred / the associated resource is accessed)browsing a large amount of information in a user-friendly manner (limited only by time , connection speed)

Using WWWWeb Browsers - programs that browse web pages, accessing their hyperlinks (associated resources)browsers bring the requested page & display their content, interpreting containing commands (text formatting , object inclusion )Web page elements : text, hyperlinks, mail addresses, objects integrate (images, graphics, multimedia objects )

Using WWWNavigation / web browsing - using hyperlinks, Back, Forward buttons + bookmarksbrowser configuration optionsother interfaces: text (lynx), voice basedhypermedia pages - contain multimedia sequences (some objects may be opened with specific programs ie Media Player)The problem of loading images / large objects (first texts, then resolution is successively improved; compressions)

WWW - special pages Maps allow zooming on selected zonesForms - accessible fill in Web forms (using specific dialogue objects) which ensure information collecting data will be retained in web databasesApplications: e-commerce (on-line orders, e-transactions, e-payments), web surveys, quiz tests, forms to fill-in personal information for accessing la various Internet services

WWW Application Search engines : www.google.com, www.altavista.com, www.yahoo.comNavigated pages are retained in cache memory browsers may run on computers that are directly connected to the Internet (phone line, TV cable) or to an Internet server / router (Internet integrated ) information transfer is based on TCP connections

WWW Functioning PrinciplesHTTP (HyperText Transfer Protocol) = protocol that describes (client) requests+ (server) answers in accessing web pagesURL (Uniform Resource Locator) - resource addressing system protocol://server/resourceHow? Where? What?URL accesses within browsers various types of resources (implicitly http protocol)

WWW Functioning Principlesfor transferring a requested web page (specified by URL) the browser:gets the servers IP (based on DNS addressing) & establishes a TCP connection sends a FTP transfer command for the requested file (the connection is released consequent to the transfer)displays file in specified format (interprets HTML source)HTTP = simple ASCII protocol (MIME type requests & answers)

WWW Functioning Principles

WWW Functioning Principlesproxy Servers Are used as communication gateways between browsers - the web server proxy solution - physical & logical (programs)a proxy server may be used for more client computers within a LAN, as a gateway that ensures Internet browsing for those computerscache memory mechanisms for browsed pagesaccess configuring mechanisms for certain web addresses by using proxy web servers

URL System a uniform system for addressing web pages + various other resources by means of web browsersprotocol://server/resource - integrate in an accessible form, various services Internet accessible using browsersimplicit protocol = http (for web pages )appear in the addressing line, hyperlinks or bookmarkshttp://www.euro.ubbcluj.ro, http://www.ubbcluj.ro/, http://www.yahoo.com, http://www.netscape.com, http://www.microsoft.com/, http://www.unige.ch/eua implicit main file - index.htm (index.html)

URL System - protocolshttp - native protocol for web pages ftp - compatibility with File Transfer Protocolftp://ftp.ubbcluj.ro/ , ftp://ftp.utcluj.rofile opening a local file -name+pathtelnet remote connectionnews - access to news (from the browser)news://comp.infosystems.www.providersgopher - system that preceded WWW (created at the Univ. of Minnesota)mailto opens an e-mail form mailto:euro@euro.ubbcluj.ro

HTML Language HyperText Markup Language describes web pages format HTML files are interpreted by browsersbased on tag principles (tags) text file files written in tag languages are portable, their interpretation being uniform & similar in different contexts (LaTeX compared to Word)Usual document processors hide tags (What You See Is What You Get)

HTML Evolution

Creating web pages directly in HTML using a text processor user un-friendly (syntax has to be well known)Using an HTML editor, which automatically generates code HTML consequent to introducing the objects using a visual interface Examples: Netscape Composer, Microsoft Front Page, Front Page Editorusing Microsoft Office web integration facilities & saving in HTML format

HTML Elements Tags (simple & parameterized) ...

Tag typesbasic - page delimiters, title, bodydocument structuring - subtitles, paragraphsformatting text & listshyperlinksobject insertion - tables, formulae, images, multimedia objects, formslatest versions - frames, Java applets, PHP tags

HTML Language Basic tagsheader ; containspage title body Tags for document structuring subtitles new line ; horizontal line new paragraph

HTML Language Text formatting tagsbold - italic - Underline - fonts & colors - List tagslist element - ordered list - unordered list -

HTML Language hyperlink tags- addresses URLfiles / local resources (local links )internal links, to document zonesParameters:HREF = URL address or local file pathNAME = name hyperlink or page zone METHODS = access methods Examples: text - local link / URL - internal link

HTML Language Tags for inserting objectsTables: parameters: BORDER, RULEStitle: ; header columns: with ALLIGN parameter (=LEFT, CENTER, RIGHT)new line : ; cell (with ALLIGN)Images: . Parameters:SRC = image / local file path - URLALLIGN = TOP, MIDDLE, BOTTOM (allign)ALT = text d to display instead of the image (if image display is deactivated ) ; ISMAP - mapspecific parameters for multimedia objects

HTML Editors MS Front Page EditorUser-friendly, visual interfacesGenerates HTML language (files are saved as HTML files)Web file saving options in Word, Excel, PowerpointExtensions XML - eXtended Markup Language different types of tags can be defined Actions: programming language sequences: Java, ASP (database), php (database) php system example: facebook)