1. Programming Languages for Web Applications

Introduction

Web-related programming tasks include HyperText Markup language (HTML) page authoring, common gateway interface (CGI) programming, generating and parsing HTML and XML (eXtensible Markup Language) documents, creating dynamic HTML pages, Web site management, and Web applications. Programming languages used for Web programming include HTML, Java, JavaScript/JScript, VBScript, Visual Basic, C/C++, and Perl.

1.1 HTML (HyperText Markup Language) and DHTML

The HTML is a structure language with a formal definition for use in creating static Web pages or HTML documents that we load from Web servers. A Web page may include the following information:

• Text of its document with appropriate settings such as front, color, alignment, numbered and bulleted lists, etc; any hypertext links to other documents, images, and other media; tables and user feedback form
• Embed client-side scripts such as JavaScript or JScript
• Embed images and media
• Embed other objects such as Java Applet program, ActiveX, audio, video, and VRML objects
• Embed video, audio, and other formats via Plug Ins

Dynamic HTML

DHTML, Microsoft Dynamic HTML technology, is merely a browser featured-or enhancement that gives your browser the ability to be interactive with:

• Dynamic contents
• Dynamic styles
• Dynamic positioning

1.2 eXtensible Markup Language (XML)

The XML is standardized method from World Wide Web Consortium for putting structured document and data in a text file for use on the Web. It uses tags and attributes like HTML, but XML uses the tags for delimit pieces of data, and leave the interpretation of data completely up to other applications. Features of XML include:

• Another file format for storing information in hierarchical formats
• XML documents can describe both themselves and their content

• Meta-language that allows you to create and format your own document markups
• XML specification: http://www.w3.org/XML

1.3 JavaScript/JScript

JavaScript is a scripting language developed by Netscape for used in delivering dynamic Web pages, and enabling client-side programming for interactivity. JScript is a Microsoft version of JavaScript. ECMAScript (European Computer Manufacturer's Association: www.ecma.ch/stand/ecma-262.htm) is a standardized JavaScript/JScript. A dynamic Web page may contain JavaScript code, which is placed inside a SCRIPT element and will be executed as the Web page is loaded. It may also be used to monitor various user events and response to user requests. The JavaScript applications may include

• Customizing Web pages
• Creating dynamic Web page
• Validating user form for CGI
• Manipulating cookies
• Interacting with frames
• Calling Java program

1.4 VBScript

VBScript, a scaled down version of Microsoft' Visual Basic, allows active scripting to be added on Web client (IE 3.0 and up), and Web server scripting in Microsoft Internet Information Server (version 3.0 and up).

1.5 Perl

Perl (Practical Extraction Report Language) is a portable, interpreted language used primarily as a tool for writing scripts that perform such functions as:

• Manipulate text in files
• Manipulate files and processes
• Extract data from files
• Write reports
• Perform networking tasks
• Write CGI scripts to generate dynamic pages for form processing
• Interface to databases

1.6 Microsoft Visual C++

Visual C++ include many MFC library classes for supporting Internet and Web programming:

• CGI programming
• Winsocket
• WinInet is a higher-level API than Winsock supporting only HTTP, FTP and gopher client programs.
• IIS's API or the MFC (Microsoft Foundation Classes) ISAPI server extensions classes
• ODBC (Open Database Connectivity) for SQL Database access and DAO (Database Access Objects)
• MFC support for ActiveX document servers
• ActiveX controls

1.7 Java

A general purpose programming language that can be used to create Applets that execute after the Web page is loaded

Features of Java

Secure - virus-free, tamper-free

Robust - not memory overwrite

Portable - run on different machine without change

Java Components

· The Java compiler - translate Java code to byte code

· The Java interpreter - reading and executing Java byte code

· The applet viewer

Byte Code - A highly portable machine language for an imaginary Java computer

Java Virtual Machine (JVM) - a computer that runs Java byte code

Just-In-Time (JIT) compilation - some JVM can translate byte code into machine language

Java Programs

· Java stand alone applications (console or window-based)

• Java applets

Java applet

• Small Java programs that run in a JVM and is incorporated into a Web Browser
• An applet runs inside a Web browser or an applet viewer
• An applet cannot manipulate the computer file system
• An applet is launched from HTML page
• Java class extends java.applet.Applet
• Defined in the java.awt package

Java Applications

- Network programming (java.net)

- Applet for dynamic Hypertext Markup Language document (Java.Applet)

- Graphical User Interface

Stand-Alone Programs

• Programs that runs on the computer in the same manner as any other window-based application

1-8 C# Language

http://www.microsoft.com/PressPass/press/2000/jun00/CSharpPR.asp

"Microsoft Introduces Highly Productive .NET Programming Language: C#

New Language Enables Rapid Development of Web Services For the Microsoft .NET Platform

REDMOND, Wash. -- June 26, 2000 -- Microsoft Corp. today announced Microsoft^® C^# ("C sharp"), a modern, object-oriented programming language built from the ground up to exploit the power of XML-based Web services on the .NET platform, which was announced last week at Forum 2000. With its Visual C++^® development system heritage, C^# will enable millions of C and C++ developers to use existing skills to rapidly build sophisticated XML-based .NET applications. To simplify integration and interoperability, Microsoft is working with ECMA, an international standards body, to create a standard for C^#, enabling multiple vendors to deliver the language and supporting tools. "

1-9 Visual Basic.NET

http://msdn.microsoft.com/vstudio/nextgen/technology/langdefault.asp

"Language Enhancements: Visual Basic.NET provides the productivity features developers need to rapidly create enterprise-critical Web applications. With support for Web Forms, Web Services, and new object-oriented language features, Visual Basic.NET delivers power while maintaining the instant accessibility that has made it the world's most popular development tool."