1. Introduction to the Internet & WWW by Dr. Khalil 1 Introduction to the Internet and World Wide Web Dr. Awad Khalil Computer Science Department AUC

2. Introduction to the Internet & WWW by Dr. Khalil 2 Internet Protocols  Web Environment – the Internet  Internet History  Internet Characteristics  The Web Building Blocks  Intranet & Extranet  Intranet Services  HTTP  Web Applications

3. Introduction to the Internet & WWW by Dr. Khalil 3 Web Environment – The Internet  The Internet is the new server for millions of clients. The Internet and the World Wide Web are evolving rapidly, if not explosively.  The WWW now increases the prominence of the Internet in information systems, strategic planning and implementation.  Organizations want to integrate the Internet “ seamlessly ” into their information systems.  Internet technology is the most widely used and successful example of client/server (thin client/fat server) technology in use today.  The Internet has reached critical mass by allowing hundreds of millions of users to connect with each other, thus making it inevitable that managers everywhere would see it as the new frontier to conquer in the quest for business profits and enhanced public services.  The use of Internet technologies facilitates the sharing of heterogeneous information in an environment that provides multiple benefits at a fraction of the cost.

4. Introduction to the Internet & WWW by Dr. Khalil 4 Web Environment – The Internet  The Internet is the new server for millions of clients. The Internet and the World Wide Web are evolving rapidly, if not explosively.  The WWW now increases the prominence of the Internet in information systems, strategic planning and implementation.  Organizations want to integrate the Internet “ seamlessly ” into their information systems.  Internet technology is the most widely used and successful example of client/server (thin client/fat server) technology in use today.  The Internet has reached critical mass by allowing hundreds of millions of users to connect with each other, thus making it inevitable that managers everywhere would see it as the new frontier to conquer in the quest for business profits and enhanced public services.  The use of Internet technologies facilitates the sharing of heterogeneous information in an environment that provides multiple benefits at a fraction of the cost.

5. Introduction to the Internet & WWW by Dr. Khalil 5 History of the Internet  ARPAnet  Implemented in late 1960’s by ARPA (Advanced Research Projects Agency of DOD)  Networked computer systems of a dozen universities and institutions with 56KB communications lines  Grandparent of today’s Internet  Intended to allow computers to be shared  Became clear that key benefit was allowing fast communication between researchers – electronic-mail (email)

6. Introduction to the Internet & WWW by Dr. Khalil 6 History of the Internet (Cont’d)  ARPA’s goals  Allow multiple users to send and receive info at same time  Network operated packet switching technique  Digital data sent in small packages called packets  Packets contained data, address info, error-control info and sequencing info  Greatly reduced transmission costs of dedicated communications lines  Network designed to be operated without centralized control  If portion of network fails, remaining portions still able to route packets

7. Introduction to the Internet & WWW by Dr. Khalil 7 History of the Internet (Cont’d)  Transmission Control Protocol (TCP)  Name of protocols for communicating over ARPAnet  Ensured that messages were properly routed and that they arrived intact  Organizations implemented own networks  Used both for intra-organization and communication to route packets

8. Introduction to the Internet & WWW by Dr. Khalil 8 History of the Internet (Cont’d)  Huge variety of networking hardware and software appeared  ARPA achieved inter-communication between all platforms with development of the IP  Internetworking Protocol  Current architecture of Internet  Combined set of protocols called TCP/IP  The Internet  Limited to universities and research institutions  Military became big user  Next, government decided to access Internet for commercial purposes

9. Introduction to the Internet & WWW by Dr. Khalil 9 History of the Internet (Cont’d)  Internet traffic grew  Businesses spent heavily to improve Internet  Better service their clients  Fierce competition among communications carriers and hardware and software suppliers  Result  Bandwidth (info carrying capacity) of Internet increased tremendously  Costs plummeted

10. Introduction to the Internet & WWW by Dr. Khalil 10 History of the Internet (Cont’d)  Internet traffic grew  Businesses spent heavily to improve Internet  Better service their clients  Fierce competition among communications carriers and hardware and software suppliers  Result  Bandwidth (info carrying capacity) of Internet increased tremendously  Costs plummeted

11. Introduction to the Internet & WWW by Dr. Khalil 11 Internet Characteristics  Hardware and software independence  Common and simple user interface  Location independence  Rapid development at manageable costs

12. Introduction to the Internet & WWW by Dr. Khalil 12 The Web Building Blocks  Internet  World Wide Web (WWW or Web)  Web Page  HyperText Markup Language  Hyperlink  Web browser  Static Web page  Dynamic Web page  Web server  Web site  HyperText Transfer Protocol

13. Introduction to the Internet & WWW by Dr. Khalil 13 The Web Building Blocks (Cont’d) 1. 1. Internet  Worldwide network of computers connected together through a standard network protocol known as Transmission Control Protocol/Internet Protocol, or TCP/IP, You can think of the Internet as the “highway” on which data travel, as in the phrase “the information super-highway.” The terms Internet and World Wide Web are often used interchangeably, but they are not synonyms. 2. World Wide Web (WWW or Web)  Worldwide network of servers that store collections of specially formatted files known as Web pages. The Web is just one of many services provided by the Internet. However, it is the World Wide Web that truly opened the Internet to the World.

14. Introduction to the Internet & WWW by Dr. Khalil 14 The Web Building Blocks (Cont’d) 3. 3. Web Page  A text document containing labels and special commands (or tags) written in a Markup Language (HTML or XML). 4. 4. HyperText Markup Language  Standard document- formatting language for Web pages. 5. Hyperlink  Web pages are linked to each other – that is, each Web page can call other Web pages – creating the effect of a “web.” Because this link can connect to different types of documents such as text, graphics, animated graphics, video, and audio, it is known as a “hyperlink.”

15. Introduction to the Internet & WWW by Dr. Khalil 15 The Web Building Blocks (Cont’d) 6. 6. Web browser  The end user application used to browse or navigate (jump from page to page) through the Web. The browser is a graphical interface that runs on the client computer, and its main function is to display Web pages. The Web browser (e.g., Netscape Navigator, Internet Explorer) requests Web pages from the Web server. 7. Static Web page  A Web page whose contents remain the same (when viewed in a browser) unless the page is manually edited. An example of a static Web page is a standard price list posted by a manufacturer. 8. Dynamic Web page  A Web page whose contents are automatically created and tailored to an end user’s needs each time the end user requests the page. For example, an end user can access a Web page that displays the latest stock selections entered by that end user.

16. Introduction to the Internet & WWW by Dr. Khalil 16 The Web Building Blocks (Cont’d) 9. 9. Web server  A specialized application whose only function is to “listen” for clients’ requests and to send the requested Web page(s). 10. 10. Web site  Term used to refer to the Web server and the collection of Web pages stored on the local hard disk of the server computer or an accessible shared directory. The Web server and the Web client communicate using a special protocol known as HyperText Transfer Protocol or HTTP. 11. HyperText Transfer Protocol  The standard protocol used by the Web browser and Web server to communicate.

17. XML, by Dr. Khalil17 Evolution !!

18. Introduction to the Internet & WWW by Dr. Khalil 18 Intranet & Extranet  Intranet is a locally owned and operated Internet whose access is carefully controlled.  Intranet architecture is based on the same basic components of the Internet: Web servers, clients using Web browser, the TCP/IP and HTTP protocols, and HTML/XML formatting.  An Extranet extends the Intranet to the corporation’s value chain.

19. Introduction to the Internet & WWW by Dr. Khalil 19 HTTP

20. Introduction to the Internet & WWW by Dr. Khalil 20 HTTP  HTTP is based on a request-response paradigm:  Connection – the client establishes a connection with the Web server  Request – The client sends a request message to the Web server.  Response – The Web server sends a response (e.g., an HTML document) to the client.  Close – The connection is closed by the Web server.

21. Introduction to the Internet & WWW by Dr. Khalil 21 HTTP Request  An HTTP request consists o a header indicating the type of request, the name of a resource, the HTTP version, followed by optional body. The main HTTP request types are:  GET – Retrieves (gets) the resource the user has requested.  POST – Transfers (posts) data to the specified resource.  HEAD – Returns only an HTTP header instead of response data.  PUT Uploads the resource to the server.  DELETE – Deletes the resource from the server.  OPTIONS – Requests the server’s configuration options.

22. Introduction to the Internet & WWW by Dr. Khalil 22 HTTP  HTTP is currently a stateless protocol – the server retains no information between requests.  This means that the information a user enters on one page is not automatically available on the next page requested.  The stateless property of HTTP makes it difficult to support the concept of a session that is essential to basic DBMS transactions.

23. Introduction to the Internet & WWW by Dr. Khalil 23 Web Application Advantages  Simplicity  Platform independence  Graphical User Interface  Standardization  Cross-platform support  Transparent network access  Scalable deployment  Innovation Disadavantages  Reliability  Security  Cost  Scalability  Limited functionality of HTML  Stateless  Bandwidth  Performance  Immaturity of development tools

24. Introduction to the Internet & WWW by Dr. Khalil 24 Web Application Architecture  Web applications may be created using various approaches. However, there are a number of components that will form essential building blocks for such applications. Typically, the Web application architecture is a three- tier architecture in which:  A Web Browser acting as the “thin” client.  A Web Server acting as the application server.  A Database Server acting as the third tier.

25. Introduction to the Internet & WWW by Dr. Khalil 25

26. Introduction to the Internet & WWW by Dr. Khalil 26 Browser Layer  The browser is the client of a Web application, and it has two major functions:  First, it handles the layout and display of HTML documents.  Second, it executes the client-side extension functionality such as Java, JavaScript, and ActiveX (a method to extend a browser’s capabilities).  The two most popular browsers at the present are Netscape Navigator (Netscape for short) and Microsoft Internet Explorer (IE). They have their own advantages and disadvantages with respect to Web applications.

27. Introduction to the Internet & WWW by Dr. Khalil 27 IE versus Netscape  Both browsers support Java, JavaScript, and IE also supports ActiveX.  Netscape is supported on numerous platforms, whereas IE runs only on Microsoft systems (e.g., Windows 2000, 98 and NT).  IE offers compatibility with other Microsoft products and can easily be integrated with existing tools such as Word, Excel and PowerPoint. The drawback is that IE heavily dependent on the Windows platforms and other Microsoft proprietary systems.  ActiveX is designed to extend the functionality of IE, and works only on Windows platforms and Macintosh System 7+.

28. Introduction to the Internet & WWW by Dr. Khalil 28 The Application Logic Layer  The application logic layer is the part of a Web application with which a developer will spend the most time. It is responsible for:   collecting data for a query (e.g., an SQL statement);  preparing and sending the query to the database via the database connection layer;  retrieving the results from the connection layer;  formatting the data for display.

29. Introduction to the Internet & WWW by Dr. Khalil 29 The Application Logic Layer (Cont’d)

30. Introduction to the Internet & WWW by Dr. Khalil 30 The Database Layer  This is the place where the underlying database resides within the Web database application.  The database is responsible for storing, retrieving, and updating data based on user requirements, and the DBMS can provide efficiency and security measures.  In many cases, when developing a Web application, the underlying database has already been in existence. A major task, therefore, is to link the database to the Web (the connection layer) and to develop the application logic layer.

31. Introduction to the Internet & WWW by Dr. Khalil 31 The Database Connection Layer  This is the component which actually links a database to the Web server.  Many current Web database building tools offer database connectivity solutions and they are used to simplify the connection process.  The database connection layer provides a link between the application logic layer and the DBMS. Connection solutions come in many forms, such as  DBMS net protocols,  API (Application Programming Interface) or class libraries, and programs that are themselves database clients. Some of these solutions resulted in tools being specifically designed for developing Web database applications.  In Oracle, for example, there are native API libraries for connection and a number of tools, such as Web Publishing Assistant, for developing Oracle applications on the Web.  The connection layer within a Web database application must accomplish a number of goals. They have to provide access to the underlying database, and they also need to be easy to use, efficient, flexible, robust, reliable, and secure. Different tools and methods fulfill these goals to different extents.

32. Introduction to the Internet & WWW by Dr. Khalil 32 The Database Connection Layer (Cont’d)

33. Introduction to the Internet & WWW by Dr. Khalil 33 Thank you