Introduction to Internet Computing

Slide 1:Introduction to Internet Computing

Dan Wang

Slide 2:Internet Computing

Internet Computing = Internet + WWW A new computing paradigm that is evolved from growth of Internet and the WWW. Integrate Web-related technologies, such as the client/server model, Applet, XML, Web security, etc. Combine advantages of Internet and WWW technologies.

Slide 3:Internet

What is the Internet? A collection of a huge variety of resources that can be reached electronically. A community of people who communicate electronically, sharing ideas and information either on a one-to-one basis, or in groups. A distributed network based on the TCP/IP protocols. Internet has been used for over 30 years. At early days, Internet is used for simple communication applications. These applications mainly use simple command prompt interface and provide straightforward ways to read, navigate and search; until WWW is created.

Slide 4:WWW

What is WWW? Acronym for World Wide Web. A hypertext-based, distributed information system initiated by Tim Bernes Lee in CERN. Hypertext is a technology for storing textual information with embedded cross references which are pointers to other information. (ex1) WWW introduces a new concept of user interface using hyperlink technology: Link to text, graphics and sounds. Link to information located on different systems or locations. Provide a simple and uniform access to various resources on the network. Can be viewed as a repository collection of documents distributed across Internet.

Slide 5:History of the Internet and WWW

Internet and WWW are exploding like wild fire. Number of web servers in organization exceeds other servers; More web-enabled applications in the last several years; “By 2004, only in Asia Pacific countries, over 95 million people will spend HK$17 billion online.”

Slide 6:History of the Internet and WWW

1957 USSR launches Sputnik, US formed Advanced Research Projects Agency (ARPA) as a response 1969, DoD’s Advance Research Projects Agency (ARPA) initiated the idea of developing a packet switch network called ARPANET. It was started with only three services: remote login (telnet), file transfer and remote printing. 1972, only 37 sites, email was introduced as one of the services. 1974, Initial design of TCP to connect multiple networks 1983, 500 sites. DARPA and UC Berkley work on implementing TCP/IP on BSD 4.2 Unix; ARPANET split into two networks: MILNET for military, ARPANET open for public.

Slide 7:History of the Internet and WWW

1987, NSFNET was created. NSF supported for education and research. A high-speed “backbone” network; ARPANET and NSFNET merged. 1989, Tim Bernes-Lee invented the WWW. Developed and released the protocols and HTML specifications. 1993, NCSA released Mosaic web browser for Unix 1994, Marc Andreessen left NCSA to start Netscape. 1995, Microsoft entered the Internet race with Internet Explorer 1.0. 1998, Larry Page and Sergey Brin set up Google Inc, a company that works on search engines.

Slide 8:Internet Pioneers

Slide 9:Internet Nowadays

Consists of various interconnected networks: ARPANET, NSFNET, CIX, BITNET, commercial networks, private networks, individual computers, PDAs, etc. Allows scientific, educational, research, commercial, and other applications. (Can you create new applications?) Keeps growing in a vary fast pace.

Slide 10:Internet Applications

Electronic mail (Email) Telnet File Transfer Protocol (FTP) Archie/Gopher/Veronica Wide Area Information Server (WAIS) Video conferencing (Netmeeting, CU-SeeMe) World Wide Web (IE, Netscape, FireFox) Instant Messenger (IRC, ICQ, QQ, Yahoo Messenger, MSN Messenger) VoIP (Skype) P2P (BitTorrent, eDonkey, eMule, Kazaa, etc.)

Slide 16:WWW Applications

WWW is one type of applications riding on the Internet, but it is a special one Applications Web browser Search engines

Slide 17:Web Browser

The web browser is the client-side software which interacts with the web server and performs invocation and interpretation of commands to exchange messages. May be window-based: Mosaic/Netscape/Internet Explorer/FireFox May be text-based: Lynx How to use?

Slide 18:Web Browser

There are three major components when the Web was created: Uniform Resource Locator (URL) HyperText Markup Language (HTML) HyperText Transfer Protocol (HTTP)

Slide 19:Web Browser

Uniform Resource Locator (URL) uniformly address the location of the resources residing in the Web space. Three important components in a URL: Protocol to access the resource Location of the server hosting the resource Name of the resource at the server E.g. http://www.polyu.edu.hk/staff.html, ftp://ftp.sura.net/pub/nic/agricultural.list

Slide 20:Web Browser

Hypertext Markup Language (HTML) With documents spanning across servers, there is need to have a way to organize the documents and standardize the display format. Designed to be simple and easy to learn. Success factors of HTML: HTML directly supports the use of simple tag markups to provide hypertext reference to other related documents. HTML is specified using simple and standardized ASCII character codes that are open and platform independent. Require no special or proprietary tools to create and publish (compare to other software such as MS Word, Word Perfect, etc) True portability and content-independence of HTML allows publication of documents across heterogeneous servers and read by multi-platform clients

Slide 21:Web Browser

Hypertext Transfer Protocol (HTTP) Control and management protocol that coordinates the transfer of resources over the web. It defines a standard protocol for web components to communicate. Application layer protocol that runs over TCP/IP. Exchange of messages is in a form of client/server model using straightforward request-reply cycle. Client sends Request while server responses to the request. HTTP is a stateless protocol. Each request-reply cycle is independent, no state is maintained between cycles.

Slide 22:Web Browser

The architecture is comprised of three modules: Controller module performs co-ordination functions between user input and invocation of other modules within the framework. Interpreter module contains all the interpreter drivers that are required to parse and interpret contents of the incoming documents. (What is the core interpreter of a web browser?) Service module houses all the drivers supporting the various transfer service protocol such as http, ftp, gopher, telnet and SMTP. (How do you specify the service to use in the web browser?)

Slide 23:Search Engines

Software programs to search for desired information on Internet Based on criteria specified by users. Composed of three major components: Spiders (or crawlers) Indices (or catalogs). Searching engines (query processor).

Slide 24:Search Engines

Two major types of searches: Keyword-based: Exact/partial match Case in/sensitive Concept-based Context-sensitive May match synonyms Some popular search engines Google (http://www.google.com) AltaVista (http://www.altavista.com) Excite (http://www.excite.com) Yahoo (http://www.yahoo.com ) Lycos (http://www.lycos.com) Mamma (http://www.mamma.com) Baidu (http://www.baidu.com) (Chinese search engine)

Slide 25:Search Engines

How does search engines work? A spider visits web pages, reads contents, follows links to other pages within the web page The web page is said being “spidered”, or “crawled”. It then builds an index, a giant list, of the visited web pages and information in them. This index forms a search engine database of searchable web pages. A site is visited regularly to keep information up-to-date. An actual search program (search engine) will then go through the database of searchable web pages to find matched indices to a search criteria. The search results are ranked in order of what it believes is most relevant.

Slide 26:Benefits of Internet Computing

Improve customer’s quality of service through directly participating and monitoring the customer’s workflow process online. Shortest path to the customers. By web-enabling services, company can immediately reach billions of customers worldwide directly. Low deployment cost. Internet and WWW is a dream marriage for companies. Low investment, and potentially high returns. Opportunities! Opportunities! Opportunities! Internet and WWW are creating more millionaires and businesses than any other business, e.g. Yahoo, Amazon, E-Travel, Google,…anyone with an IDEA, a computer, and Internet access can start your own business. Ubiquity access. Web browsers everywhere! PC, Mac, Unix, Palm, GSM Phones, T.V…The universal software!!!

Slide 27:Internet Organization

No one runs the Internet Basic workings are coordinated by various technical groups The Internet Society (ISOC) The Internet Architecture Board (IAB) The Internet Engineering Task Force (IETF) The Internet Research Task Force (IRTF) The Internet Corporation for Assigned Names and Numbers (ICANN)

Slide 28:Standardization

Open standard of Web technology is an important driving force behind the popularity of the WWW. Although HTML and HTTP came from CERN and NCSA, these two entities has been superseded by W3C and IETF W3C is a vendor-neutral consortium to drive the development of web. IETF is the protocol engineering and development arm of the Internet. IETF steers standards through a series of RFC (Request for Comments). Starts off with Internet Drafts and may proceed to RFCs HTML has evolved from ver 1.0, 2.0, 3.2 to the latest ver 4 , while HTTP evolved from ver 0.9, 1.0, to current 1.1

Slide 29:Future of Internet Computing

Interactive multimedia Video-on-demand Online gaming Electronic newspapers Electronic commerce Distance education Pervasive computing Mobile, wireless and ubiquitous More