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Mansoor Ahmed Bughio 1 Reference H.M. Deitel, P.J. Deitel and T.R. Nieto, Internet and World Wide Web: How to Program, Prentice Hall, 2002 2 Web Engineering is the application of systematic, disciplined and quantifiable approaches to development, operation, and maintenance of Webbased applications. It is both a pro-active approach and a growing collection of theoretical and empirical research in Web application development. 3 The Internet is a global system of interconnected computer networks. In contrast, the World Wide Web is one of the services transferred over these networks. It is a collection of text documents and other resources, linked by hyperlinks and URLs, usually accessed by web browsers, from webservers. 4 The Web has a massive and permanent influence on our lives! Economy, industry, education, healthcare, public administration, entertainment Tourism Systems, Train Information, Stores, . .. Web Application the Web as an application medium The reason for this: availability and to the global and permanent the comfortable and uniform access often widely distributed information producible by anyone in the form of Web pages 5 A Web application is a software system based on technologies and standards of the World Wide Web Consortium (W3C) that provides Web specific resources such as content and services through a Web browse The World Wide Web Consortium (W3C) is the main international standards organization for the World Wide Web (abbreviated WWW or W3c) 6 Web pages are stored on a Web server as ready-made, i.e. static, HTML documents and sent to the Web client in response to a request . These Web pages are usually updated manually using respective tools Disadvantages: significant cost factor for Web sites with frequent updates danger of outdated information danger of inconsistencies due to redundant storage. 7 Advantages: simplicity and stability of the system short response time Examples: static homepages simple web presences for small businesses 8 Programming network applications Large amounts of internet sites Auctions, advertising, commerce, portals with collections of sites concerning business, music, film, software, info, reports of various kinds books, search engines, education, . . Kinds of application programs . E-mail News Web based databases Client-server, per-to-peer Telephone Video . 9 Networks. A network is in this respect a collection of interconnected computers and/or other kinds of equipment Terminology: Node, a machine that is connected to the network (computer, printer, bridge, vending machine, . . . ) host, a fully autonomous computer connected to the network address, each node has a unique Address (a number of bytes) 10 packet, modern networks are packet based, meaning that the information is broken down to and sent as small chunks, each chunk of information handled separately. protocol, rules, specifying how to perform communication. 11 The client-server model Today, the client-server model is the prevailing when constructing distributed, cooperating application programs. a client asks a server for a service (as eg. information about the time) I a server accomplishes the corresponding task and delivers the service (like sending time info, sending a file from its local file system, eg. a web page) both following a protocol that enables asking for and providing services over the network 12 4. Internet Programming 4. Internet Programming 13 4. Internet Programming Web site development To develop a Web site, three steps: 1. Obtain the appropriate equipment Web Server – hardware and software 2. Register the Web Server to an Internet Service Provider (ISP) Obtain the IP address and DNS address 3. Develop the contents Internet Programming 14 4. Internet Programming Internet Programming Web service is a kind of client / server process Need interaction between client and server Programming for providing Web service can also be divided into – – Client-side programming: to define the operation to be performed on the client’s machine Server-side programming: to define the operation to be performed on the server 15 4. Internet Programming Internet Database Web Server Web Client Server-side Programming Client-side Programming Skills that are often required: • CGI • PHP • ASP • Perl • Java Servlet, … Skills that are often required: • XHTML • Javascript • Java • Dreamweaver • Flash • SMIL, XML … 16 4. Internet Programming - XHTML 4.1 XHTML – Extensible HyperText MarkUp Language 17 4. Internet Programming - XHTML Web programming using XHTML Nowadays, there are many tools that help to develop Web page – Dreamweaver, Visual studio Provide sophisticated tools to allow Web page developed in a graphical manner Finally, the job of these tools is to convert the user design to XHTML code Understanding of XHTML allows us – – fine tuning the codes generated by these tools understand the source of a Web page 18 4. Internet Programming - XHTML WHAT IS XHTML? • Unlike procedural programming languages, e.g. C, C++, XHTML is a markup language that specifies the format of document to be seen in browser • XHTML has replaced the HTML as the primary means of describing the Web page content • Become a World Wide Web Consortium (W3C) recommendation • W3C is an industry consortium • Seeks to promote standards for the evolution of the Web and interoperability between WWW products by producing specifications and reference software • Compared with HTML, XHTML provides more robust, richer and extensible features 19 4. Internet Programming - XHTML FEATURES OF XHTML • Platform independent • The same piece of code can give the same display in Mac, Linux and Windows • Text-based • Program is written with ASCII characters • Can be written using a text editor, such as notepad • An XHTML file must have an extension of .html or .htm • Information is generally enclosed inside paired tags • E.g. <html> … </html> • There are many tags in XHTML. They specify different information required to display the Web page content start tag end tag (with a /) 20 4. Internet Programming - XHTML BASIC STRUCTURE OF XHTML <html> <!-- This is a comment --> <head> <title> This is title, describing the content </title> </head> <body> This is body, main part of the page </body> </html> 21 HTML Images HTML images are defined with the <img> tag. <html> <head> <title>Page Title</title> </head> <body> <img src=“" C:\Users\Bughio\Pictures\d12.jpg" wi dth="104" height="142“> <h1>My First Heading</h1> <p>My first paragraph.</p> </body> </html> 22 HTML Elements HTML documents are made up by HTML elements. HTML elements are written with a start tag, with an end tag, with the content in between: <tagname>content</tagname> The HTML element is everything from the start tag to the end tag: 23 Nested HTML Elements HTML elements can be nested (elements can contain elements). All HTML documents consist of nested HTML elements. 24 HTML ATTRIBUTES HTML Attributes HTML elements can have attributes Attributes provide additional information about an element Attributes are always specified in the start tag Attributes come in name/value pairs like: name="value" 25 HTML Background Color The background-color property defines the background color for an HTML element: This example sets the background for a page to lightgrey: <html> <body style="background-color:lightgrey;"> <h1>This is a heading</h1> <p>This is a paragraph.</p> </body> </html> 26