Uses for scripting languages,web scripting in perl
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Scripting languages have the following key characteristics: - They are often interpreted which allows for an interactive development cycle without needing to compile code. Most languages today use a hybrid approach of compiling to an intermediate form then interpreting. - They prioritize ease of use over efficiency by sacrificing performance for quicker development and the ability to easily change requirements. - They typically have simple syntax that requires minimal programming knowledge and allows complex tasks to be performed with relatively few steps.
Uses for scripting languages,web scripting in perl
- 1. CHARACTERISTICS OF SCRIPTING LANGUAGE • Integrated Compile and Run Scripting Language behave as if they were interpreted. They are often an interactive, experimental activity that doesn’t fit well with the “edit-compile-link- run” cycle of conventional programming. A few Scripting Languages like Unix Shell and TCL(Tool Command Language) version 7 are indeed implemented as strict interpreters. However most of the languages in current use opt for hybrid technique which involve compiling to an intermediate form which is then interpreted. • Low Overhead and ease of use Based on the usage variables can be declared and initialized . Later focus was on explicit variable declaration, which requires that you declare every variable before you use it. Eg: Dim sum As Integer (or) sum=10; • Enhanced Functionality Most of the languages provide powerful string manipulation based on the use of regular expression(A regular expression is a string of characters that define the pattern or patterns you are viewing. ). Some languages support easy access to API or Object model exported by application. 6/13/2016 1Introduction to scripts and scripting
- 2. CHARACTERISTICS OF SCRIPTING LANGUAGE • Efficiency is not an issue Ease of use is achieved at the expense of efficiency eg: interpretation rather than compiling Focus is not on high performance but on the speed of development together with ability to make changes to meet new requirement. • Interpreted languages also have a simple syntax which, for the user: makes them easy to learn and use. • assumes minimum programming knowledge or experience. • allows complex tasks to be performed in relatively few steps. • allows simple creation and editing in a variety of text editors. • allows the addition of dynamic and interactive activities to web pages. • Also, interpreted languages are generally portable across various hardware and network platforms and scripts can be embedded in standard text documents for added functionality. 6/13/2016 2Introduction to scripts and scripting
- 3. Web Scripting Processing Web Forms Dynamic Web pages Dynamically generated Web pages • Processing Web Forms
- 4. DYNAMIC WEB PAGES • DHTML is about creating web pages that reacts to (user)events. • DHTML is about using JavaScript and the HTML DOM to change the style and positioning of HTML elements.
- 5. Dynamically generated HTML • It is another form of dynamic web page is one in which some or all of the HTML is generated by scripts executed on the server. • A common application is to construct a page whose content is retrieved from a database. • Examples: 1) Microsoft IIS Web Server which implements Active Server Pages(which has scripts in java script or vb script)
- 6. UNIVERSE OF SCRIPTING LANGUAGES • There is scripting universe, containing multiple overlapping worlds • The original UNIX world of traditional scripting using Perl and Tcl • The Microsoft world of visualbasic and active x controls. • The world of VBA for scripting compound documents. • The world of client-side and server-side web scripting. • Overlapping of them is very complex, as Web scripting can be done in VBScript,JavaScript,Perl or Tcl. • Perl and Tcl are used to implement complex application for large organization. 1. Eg. Tcl has been used to develop major banking system. 2. Perl is used to implement enterprise wide document management system for leading aerospace company.
- 7. TYPICAL USES OF SCRIPTING LANGUAGES INCLUDING JAVASCRIPT INCLUDE: Image or text rollovers: If the user rolls the mouse over a graphic or hypertext then a text or graphic box will appear: Creating a pop-up window to display information in a separate window from the Web page that triggered it. This is useful if the user requires to perform a simple calculation or consult a calendar for inputting dates. This is achieved by embedding ActiveX controls or Java applets into the script. Validating the content of fields: When filling in forms, each field, especially required fields denoted by an asterisk, are validated for correct input. If the field is left blank or incorrect information entered then a user message will be generated and you may not continue.
- 8. USES OF SCRIPTING LANGUAGES • Scripting languages are of two kinds: 1.Traditional Scripting 2.Modern Scripting Traditional Scripting: The activities which require traditional scripting include 1. System administration 2. Controlling Remote Applications 3. System and Application extensions 4. Experimental programming 5. Command Line interface Modern Scripting 1. Visual Scripting 2. Scriptable components 3. Client-side and Server-side Web scripting