Programming

Web applications can respond to user interaction and can have dynamic behavior when you use a programming language aside from Hypertext Markup Language (HTML). There are two types of programming in web applications: client-side and server-side programming.

Client-side programming means using a programming language that the user's web browser will execute. The most standard programming language by far for client-side programming is JavaScript. JavaScript can be included in separate text files that are referenced by the HTML files, or you can put it directly into the HTML in special HTML tags called scripttags. When the user's web browser encounters these script tags, it executes the JavaScript code contained in those tags or files.

Asynchronous JavaScript + XML (Ajax) is a term used to define a special use of JavaScript coding. You can use JavaScript code to make an HTML request to a URL and do something with the response, such as show it to a user or process it. The response is often in valid XML, which can be parsed easily by JavaScript components. Ajax allows web applications to get information for the user without the need for refreshing the web page the user is currently viewing. This behavior provides a fluid experience to the user and allows you to build web applications that provide more information.

Server-side programming refers to using computer languages to write code and execute it on the web server. This execution takes place after a user has made a request using a URL and before the web server software sends the HTML back to the user's web browser. Web applications that include server-side programming often access a database or files on the web server. Examples of web applications that use extensive server-side programming are e-commerce sites, social-networking sites, and wikis.

Server-side programming can be done using many different languages, as long as you have the server software to run the application. For example, to run Java™ web applications you will need an application server that runs Java applications such as IBM® WebSphere® Application Server or the integrated application server for IBM i. Another example would be extending the functionality of the IBM HTTP Server through the use of Common Gateway Interface (CGI) programs so that programs written in ILE RPG, COBOL, C, and C++ can be invoked. The HTTP Server can also be extended to run server-side scripting languages like Hypertext Preprocessor (PHP) and Net.Data®.

IBM provides a lot of information and resources for helping you build web applications as well as products that you can use to build enterprise-ready web applications.