Scripting Language versu system programming languages

The content posted here are the main points copied from http://home.pacbell.net/ouster/scripting.html

1. Introduction

Scripting languages and system programming languages are complementary, and most major computing platforms since the 1960's have provided both kinds of languages. The languages are typically used together in component frameworks, where components are created with system programming languages and glued together with scripting languages. However, several recent trends, such as faster machines, better scripting languages, the increasing importance of graphical user interfaces and component architectures, and the growth of the Internet, have greatly increased the applicability of scripting languages. These trends will continue over the next decade, with more and more new applications written entirely in scripting languages and system programming languages used primarily for creating components.

2. System Programming Languages

These are higher level and strongly typed compared to the assembly languages.

Higher level: Details such as register allocation, memory allocation, procedure calling sequences, passing on the parameters to the procedures are hiden from the code point of view.

Strongly Typed: From Computer point of view each location is typeless. Means we can store anything and interpret as whatever we want. But to bring stability and decrease the complexity of systems we develop languages become typed. This means a memory location might be thought to contain only integers or strings based on the type associated in the program.

And these languages are compiled before they can be run. This means they become machine depended instructions before they get executed with some exceptions.

3. Scripting Languages

Scripting languages assume that there already exists a collection of useful components written in other languages. Scripting languages aren't intended for writing applications from scratch; they are intended primarily for plugging together components.

In order to simplify the task of connecting components, scripting languages tend to be typeless: all things look and behave the same so that they are interchangeable. A typeless language makes it much easier to hook together components. There are no a priori restrictions on how things can be used, and all components and values are represented in a uniform fashion. Thus any component or value can be used in any situation; components designed for one purpose can be used for totally different purposes never foreseen by the designer.

Another key difference between scripting languages and system programming languages is that scripting languages are usually interpreted whereas system programming languages are usually compiled. Interpreted languages provide rapid turnaround during development by eliminating compile times. Interpreters also make applications more flexible by allowing users to program the applications at run-time.

4. Different tools for different tasks

In deciding whether to use a scripting language or a system programming language for a particular task, consider the following questions:

• Is the application's main task to connect together pre-existing components?
• Will the application manipulate a variety of different kinds of things?
• Does the application include a graphical user interface?
• Does the application do a lot of string manipulation?
• Will the application's functions evolve rapidly over time?
• Does the application need to be extensible?

"Yes" answers to these questions suggest that a scripting language will work well for the application. On the other hand, "yes" answers to the following questions suggest that an application is better suited to a system programming language:

• Does the application implement complex algorithms or data structures?
• Does the application manipulate large datasets (e.g. all the pixels in an image) so that execution speed is critical?
• Are the application's functions well-defined and changing slowly?

Take a look @  http://home.pacbell.net/ouster/scripting.html for elaborate explaination.

Unicode Character Set

Before talking about this particular character set we need to talk about what a character set is? Character Set is a set of symbols that represent a particular language or set of languages or can be anything one can rely on for his language representation.

Now knowing what a character set is we will talk about unicode character set. After the introduction of ASCII encoding for the common english character set which only required first 7bits of a byte, people started using the code points from 128 to 255 without any common standard. In fact few languages can't be even represented completely with one byte which ASCII was doing at that time. By the time internet got a boom and people started accessing one other's information the encoding became pretty important as the same code point represented differently in different computers as they had their own character encodings i.e. the mapping of characters to the code points. Hence to solve this, Unicode came up with a universal character set that contained almost all the writable characters in the world. And the best part is this was not restricted to only one byte or in fact any number of bytes to represent a character.

Internalization and Localization

Internalization & Localization are two buzz words when we come to web applications. People usually get confused thinking both are one and the same.

But the fact is Localization is a prerequisite to the internalization in some way.

Internalization

From a web application perspective internalization means input, output can be expected to be of any language. In more detail, say we have a comments section, where we can comment our thoughts in any language. And in see all comments we can see our inputted comment shown in the same way what we inputted.

For the above thing to happen, we need to cater all languages while taking the input and be able to process it and then store it. So every input has to be tagged with a proper character set. That means for hindi characters we need to have a character set (mapping of characters to numbers) which covers hindi characters whose code points(mapped numbers) need to be stored and while displaying use the store code point and the character set.

Saying that the character set which can take care of all the language writable symbols need to be used or we need to provide mechanism for supporting many character sets, tagging each string with appropriate character set. But to our luck we have Unicode character set which can cater all language symbols.

Localization

As said earlier localization is a kind of prerequisite for internalization. Localization is nothing but making the data represented with respect to a locale from a web application point of view. Locale is a set containing preferences like language, time format, currency and can be anything which personalizes an individual person.

For example we might want to cater to the people who doesn't know english. To do that we need to represent our data in the language they know. Say for example we want to say Hello to a french guy. Then we would like show him Bonjour. To make this happen we need to have proper database which can have translations of the things which we show in our web page.

Unicode and various encodings of it might be the next step of internalization from a developer point of view.

Enabling Rewrite Rules in apache or xampp

I installed xampp apache server recently. After using this for a while i wanted to make a rewrite rule which couldn't get set due to the default behavior of xampp which is rewrite_module not loaded.

So to enable it, goto your httpd conf file, add the following line
LoadModule rewrite_module modules/mod_rewrite.so
grep for the AllowOverride None which should be changed to AllOverride all.

Now before your rewrite rule have the folling lines
RewriteEngine on
Options +FollowSymLinks

Also sometimes you might end up getting 403 forbidden error. To solve this check for
line which is followed by
Order deny,allow
allow from None

which should be changed to the following
Order allow,deny
allow from all

Happy xampping

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