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CISC103 WEB DEVELOPMENT BASICS: • WEB SITE: • HTTPS://WWW.EECIS.UDEL.EDU/~YARRINGT/103 • ALL ASSIGNMENTS AND INFORMATION IS POSTED ON WEB SITE • ALL ASSIGNMENTS MUST BE SUBMITTED VIA SAKAI • EMAIL: [email protected] • ALL LABS ARE DUE THURSDAY AT MIDNIGHT • ALL HOMEWORKS ARE DUE SUNDAY AT MIDNIGHT • UNLESS OTHERWISE NOTED • INSTALL NOTEPAD++ OR TEXT WRANGLER ON YOUR COMPUTER INTRO TO THE INTERNET • INTERNET: • A NETWORK OF NETWORK • THE INTERNET CONSISTS OF THOUSANDS OF SMALLER NETWORKS • THEY MAY BE EDUCATIONAL, COMMERCIAL, NONPROFIT, MILITARY ORGANIZATIONS, ETC. 2-2 BRIEF HISTORY • INTERNET HISTORY • • • • • BEGAN WITH 1969’S ARPANET FOR US DEPT. OF DEFENSE 62 COMPUTERS IN 1974 500 COMPUTERS IN 1983 28,000 COMPUTERS IN 1987 EARLY 1990S, MULTIMEDIA (WWW) BECAME AVAILABLE ON INTERNET 2-3 HOW DOES THE INTERNET WORK? • PROTOCOLS • SET OF RULES • INTERNET USES TCP/IP • RULES USED FOR ALL INTERNET TRANSACTIONS • BASE PROTOCOL ON WHICH ALL OTHER PROTOCOLS ARE BUILT 2-4 HOW DOES THE INTERNET WORK? • TCP • DEALS WITH TRANSFER OF DATA • HOW IT IS BROKEN UP AND REASSEMBLED TO BE SENT ACROSS THE INTERNET • PACKETS • FIXED-LENGTH BLOCKS OF DATA • FILES ARE BROKEN UP INTO PACKETS • NOT ALL PACKETS FROM THE SAME FILE FOLLOW THE SAME PATH • DATA IS REASSEMBLED AT THE OTHER END • IP ADDRESSES • INTERNET PROTOCOL ADDRESS – A UNIQUE ADDRESS THAT IDENTIFIES EVERY COMPUTER AND DEVICE CONNECTED TO THE INTERNET 2-5 KEY INTERNET MODEL: • CLIENT/SERVER MODEL • BUILT ON TOP OF TCP/IP • CLIENT: A COMPUTER REQUESTING DATA OR SERVICES • SERVER: A HOST COMPUTER, A CENTRAL COMPUTER SUPPLYING DATA OR SERVICES REQUESTED OF IT • SERVICES CAN BE REQUESTED OVER THE INTERNET • E.G., CHECK YOUR BANK ACCOUNT • GETTING EMAIL • DOWNLOADING WEB PAGE • OFTEN MULTIPLE CLIENTS SHARE THE SERVICES OF ONE SERVER 2-6 WWW • THE WORLD WIDE WEB: • USES CLIENT-SERVER MODEL • CLIENT : YOUR BROWSER • BROWSER REQUESTS WEB PAGE FROM WEB SERVER, • WHEN IT GETS THE WEB PAGE, IT DISPLAYS THE WEB PAGE • SERVER: A COMPUTER OR SET OF COMPUTERS (ELSEWHERE) THAT GIVES WEB PAGES TO CLIENTS. • CLIENT (BROWSER) REQUESTS WEB PAGES, IMAGES, SOUNDS, MOVIES, ETC FROM SERVER. • IF SERVER CAN LOCATE IT, IT SENDS IT BACK TO BROWSER • IF IT CAN’T LOCATE IT, IT SENDS BACK AN ERROR 2-7 WWW • BROWSERS DO TWO KEY THINGS: • LOCATE WEB SITES VIA UNIQUE ADDRESSES (URL) • READ WEB PAGES AND DISPLAY THEM (DISPLAYS HTML CODE, CSS, JAVASCRIPT, ETC.) 2-8 WWW: URL • URL • A WEBSITE’S UNIQUE ADDRESS • IT CONSISTS OF • • • • THE WEB COMMUNICATION PROTOCOL, HTTP THE DOMAIN NAME OF THE WEB SERVER THE DIRECTORY OR FOLDER ON THAT SERVER THE FILE WITHIN THE DIRECTORY, INCLUDING OPTIONAL EXTENSION HTTP://WWW.UDEL.EDU/FALL13/WEBFILE.HTML protocol domain name directory file name . extension 2-9 CLIENTS, SERVERS AND THE WEB • HTTP: • THE INTERNET PROTOCOL USED TO ACCESS THE WORLD WIDE WEB • RULES THAT GOVERN COMMUNICATION BETWEEN A WEB CLIENT AND A WEB SERVER • STANDS FOR HYPERTEXT TRANSFER PROTOCOL • HTTPS • THE SECURE VERSION OF HTTP THE WEB • HTML • THE LANGUAGE USED IN WRITING AND PUBLISHING WEB PAGES • THE SET OF TAGS USED FOR FORMATTING AND LINKING TO OTHER DOCUMENTS ON THE WEB • NOT A PROGRAMMING LANGUAGE (BUT IT CAN CONTAIN PROGRAMMING CODE) • HYPERTEXT LINKS CONNECT ONE WEB DOCUMENT TO ANOTHER 2-11 OTHER TERMS • CSS – • CASCADING STYLE SHEETS • USED FOR STYLING WEB PAGE • HTML IS FOR FORMATTING • CSS IS USED FOR STYLING • JAVASCRIPT • CLIENT-SIDE SCRIPTING LANGUAGE • NOT STAND-ALONE, BUT AN ADD-ON TO HTML • MOST POPULAR SCRIPTING LANGUAGE