Internet intrarnet CIS class 1

Internet / Intranet CIS-536 Getting Started Introduction to Internet Technologies Class Agenda • Introduction – Syllabus – Homework • Introduction to Internet Technologies – Internet History and Protocols – Networking Principles: TCP/IP Web Hierarchy TECHNOLOGY Key Components Web Applications Web Forms World Wide Web Core Internet Protocols The Internet Networking Scripting CGI HTML, Browsers, Web Servers SMTP (Mail), FTP, Telnet TCP/IP, DNS, Backbone OSI Model, Ethernet, LANs Operating Systems UNIX, Windows, Other O/S Computers Mainframes, Minis, PC’s Networking Roots • Why? A Need to Transfer Data Between Computers • Issue: Computers Vary Widely – Multiple Manufacturers, Types • • • – – Variations: Speed, Disk Space, Peripherals, Technology Operating System (O/S): • • – Mainframes: IBM, BUNCH Minis: Same + DEC, DG, HP, etc PC’s: IBM, Apple Now: Unix, Windows, Mac, Other Before: IBM, BUNCH, Unix, VMS User Interface: Text-Based, Graphical, Hand-Held • The Need: – File Transfer Between Computers – Data Transfer Between Computers • Session-Based Networking Options • Basic: (One Sender / One Recipient at a Time) “Print and ReKey” – “SneakerNet” – Direct “Dumb” Connection • E.g Parallel Port – Modem • Protocols: • File Transfer Protocols – E.g XMODEM, ZMODEM • Advanced: Non-Dedicated – Shared Connection • Broadcast – Filters • Routing – Physical Networking Issues • Distance Between Machines – Local – LAN – Metropolitan (MAN) – National / International (WAN) • Public vs Private Networks • Cable Type: (e.g UTP, Coax, Fiber) • Wiring Topology 10 Network Topologies DIRECT STAR RING BUS 11 Communication Issues • Connection Type – Circuit vs Packet • Circuit: Session Based • Packet: Package Based – Packet Details • Size • Format – Routing – Bandwidth Sharing • Load Balancing • Routing – Error Handling – Security 12 The OSI Networking Model • An Attempt to Separate Physical Issues, Communication Issues, etc • The Concept: – Each Layer Is Independent • “Black Box Approach” • A Layer Has No Knowledge of Other Layer’s Internal Structure • Allows Layers to Be Swapped In and Out Easily • The Reality: – Pure OSI is Too Slow – Most Implementations Cross Layers – Nevertheless: Useful Conceptual Model to Understand Networking 13 OSI Networking Model Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data Link Layer Physical Layer 14 Internet: Pre-Commercialization – NSF’s Acceptable Use Policy: • For Research and Education Only • Commercial / For-Profit Activity Excluded – Independent Bulletin Board Systems (BBS) Begin to Convert to Usenet • 1985 – The WELL (Whole Earth Electronic Link) – New Protocols Join email, telnet, usenet • Gopher – Campus Information System • WAIS – Document Retrieval – 1987 – Over 10,000 nodes – 1990 – 100,000 nodes countries 41 Before the Web • Information Shared Publicly via FTP – Relevant Documents Listed in a Directory • Must Be Organized By Directory • User Must Know That Directory Exists • File Names Only – No Descriptive Information • Clearly a Need to Organize Information – Archie • Catalog of FTP Servers – Gopher • Menu Based Organization of Files – WAIS • Library of Files With Search Capabilities 42 Archie – – – – – The First Search Engine? Maintains a Catalog of Anonymous FTP Servers • Client Contacts Each Server Monthly – Lists All of the Files Available via Anonymous FTP – Maintains This List Locally – Based on FTP: No Special Process Needed on Server Users Login to an Archie Server • Can Search by Keyword • Lists FTP Servers Where File Can Be Found Descriptive Index • Administrator’s Keep Index of Available Files – Add Comments – No Standard Format • Comments Become Searchable Email Interface • Submit Search via email, Get Results Back as an email 43 Gopher – A Desire to Distribute Campus Information Online • Originated at University of Minnesota – Session Based • Requires a Client and Server • TCP/IP Communication via Port 70 – Menu Based System • List of Menu Choices • Can “Drill Down” a Menu • Text-Based – Most Terminals Support 25 Lines of Text – Allows Links to Other Gopher Sites • Allows Different Groups to Maintain Their Own Files • CSO – Text Based Forms / Processing • Allows FTP Through Same Interface 44 WAIS – Wide Area Information Service • Improved Search Engine • Full-Text Search and Retrieval • Session Based – TCP/IP Communication via Port 210 • Requires a “Librarian” to Maintain an Index • Servers Can Ask Another to Perform a Search • XWAIS – X-Windows GUI to WAIS 45 Internet – Pre-Commercialization • Non-Commercial Culture Develops • Lots of Public Domain Software – UNIX – The Free Software Foundation • Richard Stallman • General Public License • Spirit of Cooperation – Newsgroups • “Netiquette” – Self-Policing Rules 46 Web Hierarchy TECHNOLOGY Key Components Web Applications Web Forms World Wide Web Core Internet Protocols The Internet Networking Scripting CGI HTML, Browsers, Web Servers SMTP (Mail), FTP, Telnet TCP/IP, DNS, Backbone OSI Model, Ethernet, LANs Operating Systems UNIX, Windows, Other O/S Computers Mainframes, Minis, PC’s 47 Web Beginnings • 1991 - Internet Commericalization – NSF lifts restriction forbidding commercial traffic • 1990 – Tim Berners-Lee Proposes Web Structure to CERN (Center for European Research) – Goal: To Distribute Research Across CERN’s Many Laboratories and Affiliates • New Protocol: HTTP – Encapsulates Multiple Internet Protocols • FTP, Gopher, etc – Files Identified by URL – Uniform Resource Locator 48 Web Beginnings (2) • Hypertext Markup Language (HTML) – Modification of SGML – Standard Generalized Markup Language – Hypertext • Includes “Links” to Other Places Within the Document • Includes Links to Other Documents – Why Hypertext? • Allows Distributed Documents • Maintainability - Documents More Current • Storage Doesn’t Need to Be Duplicated 49 The Need For HTML – Need For Portable Method to Distribute Technical Documents • • • – Options • • • – GUI’s Not Prevalent – Most Used “Dumb Terminals” » Fonts, Characters Per Line, Lines Per Screen Varied Many Different Operating Systems – Hardware Limitations No Standard Word Processing Applications Plain Text – No Formatting Print-Based – Postscript, GIF – Large Files, No Searching Text-Based – TeX, RTF, nroff – Describe How to Print Document » Display Capabilities Vary Solution: HTML • Describes Document’s Content, Not its Format 50 Web Client (Browser) Development • HTML Requires an Application to Display it • First Browser: www (1991) – Text Based • GUI’s Becoming More Prevalent – Apple Macintosh – MS-Windows – X/Motif (UNIX) • First Graphical Browsers – 1993 - Mosaic (NCSA – National Center for Supercomputing Applications) • • Available on all Platforms Public Domain • Netscape Communications Corporation (1994) – Private Corporation Founded By Mosaic’s Creators • Microsoft Internet Explorer 51 Browser Wars • Netscape – Extended HTML With “Custom” Extensions – “Plug-Ins” – Allow Local Applications to Run Within Browser • Microsoft Internet Explorer – – – Based on Spyglass’ Mosaic Custom Extensions to HTML Active X – Microsoft Equivalent of Plug-Ins • Other Browsers Left Behind – – Custom Extensions Make it Difficult to Keep Up Changes the Web Significantly • – Universal Accessibility is Sacrificed – Requires GUI – Requires Current Hardware HTML Standards Expand Rapidly • Goal: To Create a Single Standard Used by Both Browsers 52 Who’s Managing the Web? • Web Commercialization/Competition Changes Culture – Internet Experiences Exponential Growth • 1994 - CERN/MIT Found the World Wide Web Consortium (W3C) – – – Attempt to Manage/Control Standards Member Organizations Only IETF – Internet Engineering Task Force • Protocol Engineering and Development – Open to Individuals • CERN Drops Out – INRIA Takes Over for CERN (Funded by EC) • New Extensions to Web Usage – – Two-Way Communications (e.g Forms) Advanced UI Functionality (Scripting, Java) 53 Web Hierarchy TECHNOLOGY Key Components Web Applications Web Forms World Wide Web Core Internet Protocols The Internet Networking Scripting, Applets CGI HTML, Browsers, Web Servers SMTP (Mail), FTP, Telnet TCP/IP, DNS, Backbone OSI Model, Ethernet, LANs Operating Systems UNIX, Windows, Other O/S Computers Mainframes, Minis, PC’s 54 For More Information – Portal • http://www.internet.com – Internet History • Hobbes Internet Timeline – http://info.isoc.org/guest/zakon/Internet/History/HIT.html • Free Software Foundation /GNU – http://www.gnu.org – Networking • Brandeis: Computer Networks and Data Communications – TCP/IP, FTP, etc • Brandeis: TCP/IP • Winsock Programming – Windows Sockets Network Programming by Bob Quinn and Dave Shute Addison-Wesley Brandeis University Internet/Intranet Spring 2000 57 ... UCLA 16 4.67.80.0 J Smith 16 4.67.80 .12 3 Chicago 19 8.23.0.0 Polaroid 12 9.64.95.0 Waltham 12 9.64.0.0 Brandeis 12 9.64.99.0 Feldberg 12 3 12 9.64.99 .12 8 Cambridge 12 9.70.0.0 MIT 12 9.70.53.0 Lab 12 9.70.53. 41. .. Networks) – IP addresses: 1. 0.0.0 to 12 7.0.0.0 • Class B (Large Networks) – IP addresses: 12 8.0.0.0 to 19 1.254.254.254 • Class C (Small/Medium Networks) – IP addresses: 19 2.0.0.0 to 223.254.254.254 Subnetting... Application Doing the Communication 16 TCP / IP • The Basic Protocol of the Internet • Covers Layers 3-4 of the OSI Model ( Network / Transport Layers) • Multiple Layer 1- 2 (Physical / Data Transport)