introduction to web application development
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This document provides an introduction to web application development, including the history of the World Wide Web and how it works. It describes the basics of web clients and servers, URLs, HTML, and how communication is established over the internet. It then distinguishes between static and dynamic web pages, and discusses client-side scripting like JavaScript and Java applets as well as server-side scripting using languages like PHP, ASP, and JSP to generate dynamic web content. Finally, it lists some common web development tools.
introduction to web application development
- 1. INTRODUCTION TO WEB APPLICATION DEVELOPMENT BIT05206 Web Application Development
- 2. Contents Introduction to WWW Web Application Development
- 4. WWW History 1989 - Birth of WWW ◦ Tim Berners-Lee & his associates at CERN 1990 - First Web Browser ◦ Used within CERN 1991 - Public offering of WWW 1993 - Birth of Mosaic ◦ Graphical, multimedia browser from NCSA 1994 - First commercial browser ◦ By Netscape communications founded by Jim Clark and Marc Andreessen
- 5. Web Advantages Creates a virtual hyperspace ◦ Beyond geographical constraints ◦ Break computer hardware and software obstacles ◦ Bring the whole world together A low cost way to Share, maintain, and distribute Information ◦ Intranet ◦ Electronic commerce ◦ Customer support
- 6. Web Client (browser) Internet
- 7. Web Server
- 8. Web Surfing (Logical View)
- 9. Web Surfing (Network View)
- 11. Network Basis TCP/IP protocol ◦ Transmission Control Protocol and Internet Protocol ◦ Specifies how two computer exchange data HTML ◦ Content-based or structural markup language, where the codes describe what the contents of the document are. ◦ Codes are used to indicate the various parts of the document, such as headings, paragraphs, lists, etc IP address ◦ Every computer has a unique IP address ◦ 32 bits in three 8 bit number groups ◦ 131.96.142.17
- 12. Network Basis Domain name system (DNS) ◦ Symbolic name for IP address stm1.uum.edu.my ◦ Communication is established by mapping a domain ◦ name to its IP address URL ◦ Internet address consist of protocol host name path
- 13. URL Abbreviation of Uniform Resource Locator, the global address of documents and other resources on the World Wide Web. The first part of the address indicates what protocol to use, and the second part specifies the IP address or the domain name where the resource is located. For example, the two URLs below point to two different files at the domain pcwebopedia.com. The first specifies an executable file that should be fetched using the FTP protocol; the second specifies a Web page that should be fetched using the HTTP protocol: •ftp://www.bbc.com/stuff.exe •http://www.bbc.com/index.html
- 14. URL <protocol> <host name> <path> HTTP--Hypertext Transfer Protocol ◦ Protocol for accessing World Wide Web documents FTP--File Transfer Protocol ◦ Protocol for transferring files from one computer to another Gopher ◦ Protocol for accessing documents via Gopher menus (archaic; no longer widely used) Telnet ◦ Protocol that allows users to logon to a remote computer
- 15. URL Host Name <protocol> <host name> <path> <host>.<organization>.<org type> www.ucc.co.tz www.google.com www.acm.org www.jpa.gov.my
- 16. Organization Types .org : non-profit organizations .com : commercial hosts .net : network hosts .edu : educational institutions .int : international treaty organizations .gov : government agencies and organizations .mil : U. S. military .tz : represent country (Tanzania)
- 17. URL Examples Full URL ◦ http://www.uum.edu.my/welcome.htm ◦ http://www.ucc.co.tz/services/index.ph p ◦ http://www.w3schools.com/html/ Not all characters can be used in URL
- 18. MIME Typing System Multipurpose Internet Mail Extensions A file type naming system on the Internet ◦ .html (or .htm), .gif, .mpeg, .xls Allow a browser to determine how to work correctly with given files ◦ Handle by the browser itself ◦ Call a helper application ◦ Example: use Adobe Acrobat to read .PDF files use Microsoft Excel to read .xls files
- 20. Static VS Dynamic HTML documents are usually static The contents can only be changed manually There are needs for dynamic documents ◦ Search results ◦ Database access ◦ Context sensitive reply Static ◦ page appears exactly as it was encoded, nothing changes Dynamic ◦ page is compiled, or able to be changed
- 21. Dynamic Web pages Applications executed by the server at run-time to process client input or generate document in response to client request Generating dynamic Web pages requires programming
- 22. Scripts: Server-Side VS Client- Side Server-side ◦ the first type possible on the Web ◦ action occurs at the server Client-side ◦ generally easier to implement ◦ may be prepared and implemented offline ◦ action occurs on the client side (browser)
- 23. Client-Side Scripting Client side scripts are embedded inside HTML document. They are interpreted by browser. When Web browser encounters a script, it calls a scripting interpreter, which parses and deciphers the scripting code. Provide response to questions and queries without interventions from the server ◦ Validate user data ◦ Calculate expressions ◦ Link to other applications
- 24. Client-Side Scripting Client side advantages ◦ Faster response time ◦ Better animation ◦ Simpler server programs Client side disadvantages ◦ Longer load time ◦ Browser compatibility ◦ Complexity in web page design
- 25. JavaScript JavaScript (most common) –a scripting language for Web pages, developed by Netscape in 1995 –JavaScript code is embedded directly in HTML (interpreted by browser) –good for adding dynamic features to Web page, controlling forms and GUI Advantage ◦ Easy to learn and use ◦ Wide browser support ◦ Protection of local resources Disadvantage ◦ Browser compatibility issues ◦ Not object oriented ◦ Unable to gain access to local resources
- 26. Java Applet Java applets – (can be server-side or client-side_ –can define small, special-purpose programs in Java called applets –provides full expressive power of Java (but more overhead) –applets are included in Web pages using special HTML tags –interpreted by the Java Virtual Machine embedded in the browser –good for more complex tasks or data heavy tasks, such as graphics
- 27. Example Visit this site Java Applet Java Script
- 28. Java Applet Advantage ◦ High functionality ◦ Object oriented and full graphics functionality ◦ Protection of local resources ◦ Wide Browser support ◦ With Java2, be able to gain access to local resources with signed applets Disadvantage ◦ JVM compatibility issues ◦ Difficulty to install and configure for local access ◦ Loading time and performance may be poor for large application.
- 29. Server-Side Scripting Advantages Allows creation of dynamic web pages Modifies HTML code on the server before sent to client Uses databases such as Access and Oracle Responds to user input Disadvantages More complicated then HTML (with debugging) Slower to load on the server Harder to learn Web server must be enabled
- 30. Examples of Server-Side Scripts CGI (Common Gateway Interface) ◦ A standard for interfacing external applications with information servers, such as HTTP or Web servers ◦ CGI program is any program designed to accept and return data that conforms to the CGI specification ◦ CGI program can be written in any language that allows it to be executed on the system, such as: C/C++, Fortran, PERL, TCL, Any Unix shell, Visual Basic, AppleScript etc. PHP (Hypertext Preprocessor ) Widely-used Open Source general-purpose scripting language that is especially suited for Web development and can be embedded into HTML.
- 31. Examples of Server-Side Scripts Active Server Pages (Microsoft) ◦ ASP is a Microsoft Technology and run on IIS (Internet Information Server) & PWS (Personal Web Server) Java Server Pages (Sun) ◦ Sun's solution for developing dynamic web sites ◦ JSP enable the developers to directly insert java code into jsp file, this makes the development process very simple and its maintenance also becomes very easy
- 32. Web Development Tools Many high-level tools exist for creating Web pages ◦ e.g., Microsoft FrontPage, Netscape Composer, Adobe PageMill, Macromedia DreamWeaver, ◦ also, many applications have "save to HTML" options (e.g., Word)