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Advanced Web Technology

Advanced Web Technology. What is Web. Web, is a way of accessing information over the medium of the Internet. It is an information-sharing model that is built on top of the Internet. The Web uses the HTTP protocol , only one of the languages spoken over the Internet, to transmit data.

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Advanced Web Technology

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  1. Advanced Web Technology

  2. What is Web

  3. Web, is a way of accessing information over the medium of the Internet. • It is an information-sharing model that is built on top of the Internet. • The Web uses the HTTP protocol, only one of the languages spoken over the Internet, to transmit data. • The Web also utilizes browsers, such as Internet Explorer or Firefox, to access Web documents called Web pages that are linked to each other via hyperlinks. • Web documents also contain graphics, sounds, text and video.

  4. How it works • AWeb page on the World Wide Web normally begins by typing the URL of the page into a Web browser. • The Web browser then initiates a series of communication messages, behind the scenes, in order to fetch and display it. • First, the server-name portion of the URL is resolved into an IP address using the domain name system. • This IP address is necessary to contact and send data packets to the Web server.

  5. The browser then requests the resource by sending an HTTP request to the Web server at that particular address. • The browser translates the data it has been given in to HTML and displays the results to the user.

  6. HTML

  7. HTML is a language for describing the web pages. • HTML stands for Hyper Text Mark-upLanguage • It provides a means to create structured documents by denoting structural semantics for text such as headings, paragraphs, lists etc as well as for links, quotes, and other items. • It allows images and objects to be embedded and can be used to create interactive forms. It is written in the form of HTML elements consisting of "tags" surrounded by angle brackets within the web page content. • HTML is not a programming language, it is a mark-up language • A mark-up language is a set of mark-up tags

  8. HTML uses mark-up tags to describe web pages • HTML is a data format, not a programming language. • A Web browser interpret the set of HTML tags within the page in order to display the page on your screen.HTML Documents - Web Pages • HTML documents describe web pages • HTML documents contain HTML tagsand plain text • HTML documents are also called web pages • The purpose of a web browsers (like Internet Explorer) is to read HTML documents and display them as web pages. The browser does not display the HTML tags.

  9. An HTML tag An HTML tag is a code element that tells the Web browser what to do with your text. Each tag will appear as letters or words between a < (less than sign) and a > (greater than sign). • Any Web page you create will contain the following tags at the start of the page: • <HTML>: tells the Web browser that this is the beginning of an HTML document • <HEAD>: tells that Web browser that this is the header for the page.

  10. <TITLE>: tells the Web browser that this is the title of the page • <BODY>: tells the Web browser that this is the beginning of the Web page content -- everything you want to say and see on your page will follow this tag.

  11. <html> <body> <h1>My First Heading</h1> <p>My first paragraph</p> </body> </html>

  12. Example Explained The text between <html> and </html> describes the web page The text between <body> and </body> is the visible page content The text between <h1> and </h1> is displayed as a heading The text between <p> and </p> is displayed as a paragraph

  13. HTM or HTML Extension? • When you save an HTML file, you can use either the .htm or the .html extension. • HTML Links • HTML links are defined with the <a> tag. • <a href="http://www.w3schools.com">This is a link</a> Note: The <a> tag contains an attribute (href) to provide the link address.

  14. HTML Images • In HTML, images are defined with the <img> tag.  • The <img> tag is empty, which means that it contains attributes only and it has no closing tag. • To display an image on a page, you need to use the src attribute. Src stands for "source". The value of the src attribute is the URL of the image you want to display on your page. • HTML images are defined with the <img> tag. • <img src="constr4.gif" width="144" height="50" /> • Note: The name of the image and the size are provided as attributes.

  15. ASP

  16. ASP stands for Active Server Pages. • ASP is a program that runs inside IIS. • IIS stands for Internet Information Services. • IIS comes as a free component with Windows 2000. • ASP is a Microsoft Technology. • To run IIS you must have Windows NT 4.0 or later version. • An ASP file can contain text, HTML, XML, and scripts . • Scripts in an ASP file are executed on the server. • An ASP file has the file extension ".asp“.

  17. When a browser requests an ASP file, IIS passes the request to the ASP engine. • The ASP engine reads the ASP file, line by line, and executes the scripts in the file. • Finally, the ASP file is returned to the browser as plain HTML. • The ASP source code can contain procedures and functions. • With ASP, you can both create and retrieve cookie values. • The default scripting language used for writing ASP is VBScript, although you can use other scripting languages like JScript (Microsoft's version of JavaScript).

  18. What can ASP do for you? • Dynamicallyedit, change or add any content of a Web page • Respond to user queries or data submitted from HTML forms • Access any data or databases and return the results to a browser. • Customize a Web page to make it more useful for individual users. • Provide security since your ASP code can not be viewed from the browser • Clever ASP programming can minimize the network traffic

  19. DHTML

  20. DHTML stands for Dynamic HTML. • DHTML is a TERM used to describe the technologies used to make web pages dynamic and interactive. • DHTML combines HTML, JavaScript, DOM, and CSS. • JavaScript • JavaScript was designed to add interactivity to HTML pages • JavaScript is a scripting language • A scripting language is a lightweight programming language • JavaScript is usually embedded directly into HTML pages • JavaScript is an interpreted language (means that scripts execute without preliminary compilation) • Everyone can use JavaScript without purchasing a license

  21. DHTML is often used to make rollover buttons or drop-down menus on a web page. • disadvantages of DHTML are that it is difficult to develop and debug due to varying degrees of support among web browsers of the technologies involved. • Example 1 for DHTML • Example 2 for JavaScript • Example 3 for JavaScript

  22. The DOM defines a standard for accessing and manipulating HTML documents. • DOM is platform- and language-independent.

  23. HTML Vs DHTML

  24. HTML DHTML DHTML (Dynamic HTML) is HTML, JavaScript and CSS combined. DHTML is much more powerful. It is not simple and complicated to learn. DHTML Display the dynamic contents. File extension is .dhtml • It is only HTML. • It is not powerful. • HTML is simpler, and easier to learn. • HTML Display the static contents. • File extension is .html

  25. JSP Java Server Pages

  26. JSP is a server-side technology much like ASP developed by Sun. • With JSP you can create dynamic web pages by putting Java code inside your HTML pages this makes the development process very simple and its maintenance also becomes very easy.. • The code is executed by the web server before the page is returned to the browser. • Since JSP uses Java, the technology is not restricted to any server-specific platform. • JSP technology enables rapid development of web-based applications.

  27. JSP syntax has two basic forms, script let and mark-up. • JDBC provide excellent database connectivity in heterogeneous database environment. Using JSP and JDBC its very easy to develop database driven web application.  • The Java Server Pages specification extends the Java Servlet API to provide web application developers with a robust framework for creating dynamic web content on the server. JSP include HTML, and XML templates, and Java code, which is secure, fast, and independent of server platforms

  28. JSP pages are compiled first time before it is processed by server and after that JSP pages is directly executed , this helps the server to handle JSP pages more faster. • JSP supports • JDBC • RMI • JMS

  29. <HTML> <BODY> Hello!  The time is now <%= new java.util.Date() %> </BODY> </HTML> Notice that each time you reload the page in the browser, it comes up with the current time. The character sequences <%= and %> enclose Java expressions, which are evaluated at run time.

  30. To process a JSP file, we need a JSP engine that can be connected with a web server or can be accommodated inside a web server. • Firstly when a client browser requested for JSP file, the web server recognizes the .jsp file extension and understands that the requested resource is a Java Server Page. Request Response Web Server Client JSP Engine

  31. Then the web server passes the request to the JSP engine. • The JSP page is then translated into a Java class, which is then compiled into a Servlets and the Servlets are run on the server. • The result of the execution is send to the client’s browser in the form of HTML.

  32. CGI Common Gateway Interface

  33. (CGI) is a standardprotocol for interfacing external application software with an information server, commonly a web server. • The task of such an information server is to respond to requests (in the case of web servers, requests from clientweb browsers) by returning output. • Each time a request is received, the server analyzes what the request asks for, and returns the appropriate output. • The two simplest ways for the server to do this, are the following: • 1. if the request identifies a file stored on disk, return the contents of that file;

  34. 2. if the request identifies an executable command and possibly arguments, run the command and return its output • Normal HTTP documents are static; a text file that doesn't change • CGI is a program that is executed in real-time to produce output.

  35. CGI (Common Gateway Interface) is a way for web servers and server-side programs to interact with external program. • CGI is completely independent of programming language, operating system and web server. • Currently it is the most common server-side programming technique and it's also supported by almost every web server in existence. • Moreover, all servers implement it in (nearly) the same way, so that you can make a CGI script for one server and then distribute it to be run on any web server. • A CGI script is invoked by an HTTP server, usually to process user input submitted through an HTML <FORM> or <ISINDEX> element.

  36. Common Gateway Interface (CGI) ISS, 2005

  37. Java Script

  38. JavaScript is an interpreted programming. • In general, script languages are easier and faster to code in than the more structured and compiled languages such as C and C++. • JavaScript is used in Web site development to do such things as: • Automatically change a formatted date on a Web page • Provide popup window • Text or a graphic image to change during a mouserollover

  39. JavaScript is the most popular scripting language on the internet, and works in all major browsers, such as Internet Explorer, Firefox, and Opera. • JavaScript code can be imbedded in HTML pages and interpreted by the Web browser. • The HTML <script> tag is used to insert a JavaScript into an HTML page. • Loops in JavaScript are used to execute the same block of code a specified number of times or while a specified condition is true.

  40. VBScript is a scripting language • A scripting language is a lightweight programming language • VBScript is a light version of Microsoft's programming language Visual Basic • When a VBScript is inserted into a HTML document, the Internet browser will read the HTML and interpret the VBScript. • The VBScript can be executed immediately. • VBScript is installed by default in every desktop release of Microsoft Windows since Windows 98

  41. Other web browsers such as Firefox, and Opera do not have built-in support for VBScript. • VBScript provides functions and sub-routines, basic date/time, string manipulation, math, user interaction, error handling, and regular expressions. • Besides client-side web development, VBScript is used for server-side processing of web pages, most notably with Microsoft Active Server Pages (ASP).

  42. JavaScript vs. VbScript

  43. Java Script Vb Script web browsers such as Firefox, and Opera do not have built-in support for VBScript. The default scripting language used for writing ASP is VBScript, vbscript is mainly used on the server side Vb not case sensitive Vb script is developed by ms • Java Script works in all major browsers, such as Internet Explorer, Firefox, and Opera. • The default scripting language used for writing ASP is not Java Script, • it is used on client side • Java is case sensitive • Java script by Sunmicrosystems

  44. ISAPI provides a vendor-independent way of extending the functionality of your web server. • It offers more flexibility than the CGI interface and avoids all the performance limitations. • ISAPI code is written in C language. • ISAPI code is compiled as a shared object, also known as a dynamic library. This code automatically becomes part of the web server when a web site is started, and can then interact with data structures and talk with a connected client.

  45. Since the web server already has ISAPI code loaded, it is a very fast mechanism for dynamically providing or modifying content. • ISAPI consists of two components: Extensions and Filters. • Both Filters and Extensions must be compiled into DLL files which are then registered with IIS to be run on the web server.

  46. Extensions • ISAPI Extensions are true applications that run on IIS. • They have access to all of the functionality provided by IIS. ISAPI extensions are implemented as DLLs that are loaded into a process that is controlled by IIS. • Clients can access ISAPI extensions in the same way they access a static HTML page. • Certain file extensions or a complete folder or site can be mapped to be handled by an ISAPI extension.

  47. Filters • ISAPI filters are used to modify or enhance the functionality provided by IIS. • Filters can be programmed to examine and modify both incoming and outgoing streams of data. • Filters are implemented as DLL files and can be registered on an IIS server on a site level . • Handle encryption and compression. • Control which physical file gets mapped to the URL

  48. Common ISAPI applications • This is a list of common ISAPI applications implemented as ISAPI extensions: • Active Server Pages (ASP), installed as standard • ASP.NET, installed as standard on IIS 6.0 onwards • Perl ISAPI ,available for free to install • PHP, available for free to install.

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