Java Applet (applet)
It is also possible to create small programs to interface in a programming language like Java. These little programs are called applets or applets. They are completely autonomous but possibly parameterized and integrated into a webpage. They are uploaded to the web page and executed by the client computer.
The code is independent of the platform through the Java Virtual Machine (a small plug-in Java).
Java programming is complex and requires good programming skills. Many tools exist for development.
Performance is limited by the download and installation of the virtual machine.
On the web, we found a large number of application applets: games, ‘chats’, menus, etc. Applets run well on multi-user. The functionality of applets is strictly limited level security (for example, an applet could never launch an application on the client machine).
Attention all security levels of all browsers does not accept the launching applets.
In addition, the Java virtual machine runs its own memory allocations (in C language, memory is managed manually), and Java applications take more resources.
ActiveX is a solution for creating applications developed by Microsoft. The operating principles are very similar to the operation of applets. See also Component Object Model
The code is dependent on the platform most often (usually Windows and Internet Explorer)
Programming can be done with multiple languages (C, Visual Basic, Java) but requires good programming skills. Many tools exist for development.
Performance is good with the possibility of compiling and the possibility of memorization program at the client.
The possibilities of using ActiveX are enormous and there are few limitations safe. Because of this and the link with a platform, ActiveX are often reserved for Intranets.
The Client-Side Web Programming
The objects do not provide all the solutions to the needs of interactive and dynamic sites or are sometimes cumbersome to implement. You can then move on to programming for better interaction with the HTML page.
When a visitor requests a simple HTML page (with or without objects) by entering an address or URL, the web server it simply returns the contents of the requested page, the browser interprets the HTML content and plug-ins interpreting objects, calling in turn the object content to the web server.
If the code client side is inserted into the page, the web server also return the page to the client, including code. So, again the web browser should interpret the code and do what the code asks.
The client-side programming will be used mainly in the case of form validation (mandatory fields, small stones, etc.) and creating small animations (scrolling menus etc.).
The program uses client-side scripting languages. Unlike other programming languages, such languages are not compiled. They are interpreted by the visitor’s web browser, and their syntax is less stringent than the language of developers (non-typed variables, a ‘priori’, the semicolon at the end of instruction is optional etc.):
- VBScript is the scripting language developed by Microsoft based on the Visual Basic. This language is interpreted by browsers based on those developed by Microsoft (or Internet Explorer and Maxthon). It is rarely used on the Internet (but sometimes used on intranets).
Advantages And Disadvantages Of Client-Side Programming
The client-side programming is lightweight and relatively simple to implement (not too complex syntax).
The code is sent as is to the client, and therefore visible to him (if he looks at the sources of his page) and therefore insecure. The smooth running of the program depends entirely on the client’s browser, its configuration and its security level.
There is thus no question of linking the website to a database.
The Server-Side Web Programming
When inserting server-side programming in a page when the visitor requests the page, the server will first read it, it will interpret the code server and encapsulate the result in the HTML page. This will be shipped to the visitor without any trace of the server code. The visitor is then a pure html page (possibly even the client code).
In this process, we gain enormously in securing the code. It was also a large number of possible interactions with other systems or applications such as databases.
The page files “server side” generally an extension other than .htm or .html. The extension will depend on the technology used.
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