Languages on the Internet

Common Gateway Interface (CGI)

In the early days of the World Wide Web, when static HTML pages were the norm, the need to create dynamic, data‑driven content was already evident. The Common Gateway Interface, or CGI, emerged as the first standard to bridge that gap. Its design was deliberately simple: a web server would invoke an external program whenever it received a request that required server‑side processing. That external program could be written in any language capable of reading from standard input and writing to standard output, making CGI remarkably versatile. Perl, C, and, later, Python and Ruby were common choices, each bringing its own strengths to the table.

When a client submits a form, the web server forwards the form data to the CGI script as key‑value pairs in the query string or in the request body. The script parses this data, performs whatever logic is needed - database lookups, calculations, or file manipulations - and then outputs a complete HTML document back to the server. The server simply relays this output to the client, completing the round trip. This process gave early developers a way to create searchable websites, handle user registrations, and even support simple e‑commerce transactions.

CGI’s architecture, however, came with performance costs. Each request spawns a new process or thread, which is expensive in terms of CPU and memory. This inefficiency became a bottleneck as traffic grew. Moreover, security concerns rose with the exposure of the server’s file system and environment variables to poorly written scripts. Buffer overflows in C programs or unfiltered input in Perl scripts could lead to privilege escalation or data leaks.

To mitigate these issues, extensions such as FastCGI were developed. FastCGI keeps a pool of persistent worker processes alive, dramatically reducing the overhead of process creation. By decoupling the web server from the application logic, FastCGI also allows developers to write CGI‑compatible scripts in languages that support multi‑threading or non‑blocking I/O, thus improving scalability.

While modern web frameworks and microservice architectures have largely eclipsed raw CGI, the interface remains a foundational concept. Understanding CGI helps developers appreciate the evolution of server‑side scripting and the importance of separating concerns between web server logic and application code. Many contemporary technologies - Node.js, Go, Rust, and even Java with Servlet containers - borrow elements of CGI’s request‑response cycle, adapting it to newer performance and security requirements.

Today, most dynamic web sites no longer rely on CGI alone. However, the interface still finds use in lightweight applications, custom CGI scripts for legacy systems, and as an educational tool for learning how HTTP, processes, and inter‑process communication work in web environments.

JavaScript and Jscript: Client‑Side Scripting

JavaScript entered the scene as a quick, browser‑side solution to enhance interactivity without needing a round trip to the server. Originally called LiveScript, it was renamed JavaScript in 1995 to ride the popularity wave of Sun’s Java language. Though the names are similar, the two languages share little in common, aside from the fact that both are object‑oriented.

The browser became the runtime environment. A JavaScript engine parses the script, builds an abstract syntax tree, and then executes it within the browser’s memory sandbox. The Document Object Model (DOM) provides a tree‑structured representation of the web page, allowing scripts to read and modify elements, attributes, and styles on the fly. This capability turned static HTML into dynamic, responsive interfaces: drop‑downs that change options based on prior selections, image galleries that preload thumbnails, and modal dialogs that appear after a button click.

JavaScript’s event system is central to its interactive power. Browsers fire events - such as “click”, “mouseover”, “keyup”, or “load” - and scripts can attach handlers that react accordingly. This asynchronous model enables smooth user experiences: a single page can perform many tasks without reloading. For example, an e‑commerce site can update the cart count instantly after adding an item, without contacting the server.

While JavaScript originally served only the client, its ecosystem expanded dramatically. The standard evolved with ECMAScript editions, adding features like arrow functions, classes, promises, and modules. These changes, coupled with the emergence of powerful front‑end frameworks - React, Angular, Vue, Svelte - made it possible to build large, maintainable applications entirely within the browser.

Server‑side JavaScript also arrived with Node.js in 2009. Node runs the V8 engine (the same engine that powers Chrome) outside the browser, offering a non‑blocking I/O model that is ideal for real‑time applications. Node’s npm ecosystem provides thousands of reusable packages, making it possible to serve dynamic pages, build APIs, and manage server resources with the same language that powers the front‑end.

Security remains a key concern. Because the script runs on the client, it can be inspected, modified, or blocked by the user. Developers therefore treat JavaScript as an interface layer, performing input validation both client‑side (for usability) and server‑side (for security). Techniques such as Content Security Policy (CSP) headers help mitigate cross‑site scripting (XSS) attacks by restricting the sources from which scripts may be loaded.

Today, JavaScript dominates web development. Every major browser implements it, and virtually all web applications rely on it in some form. Understanding its origins, event loop, and modern syntax is essential for any developer working with dynamic web pages.

Java and Applets: Early Enterprise Java on the Web

Java was introduced by Sun Microsystems in 1995 with the promise of “write once, run anywhere.” This principle was built around the Java Virtual Machine (JVM), an interpreter that converts Java bytecode into native machine instructions at runtime. Java’s portability made it attractive for building web‑based applications that could run on any platform with a JVM installed.

Early on, web browsers began adding support for Java applets - small Java programs embedded in HTML pages. Applets ran inside the browser’s JVM sandbox, providing a way to deliver interactive graphics, complex UI components, and rich media directly within a webpage. For instance, a real‑time data visualization or a 3D product model could be delivered to users without requiring additional plug‑ins or downloads.

Applets communicated with the server through the Java Networking API, enabling them to request resources, send user input, or receive updates. However, their reliance on a browser‑side JVM introduced several challenges. Users had to install a Java Runtime Environment (JRE) on each device, and many browsers deprecated applet support due to security vulnerabilities. Additionally, applets were not as lightweight as JavaScript, making them less suitable for simple interactive tasks.

To address the growing demand for server‑side Java capabilities, the Java Servlet specification was introduced. Servlets are Java classes that run on the server and generate dynamic content. By handling HTTP requests, they can access databases, perform business logic, and produce HTML, XML, or JSON responses. The introduction of JavaServer Pages (JSP) built on servlets, allowing developers to embed Java code directly within HTML, similar to how PHP or ASP injects logic into pages.

JavaBeans and Enterprise JavaBeans (EJB) further expanded Java’s role in large‑scale applications. JavaBeans encapsulate reusable components that can be manipulated visually in development environments, while EJBs provide transaction management, security, and concurrency control for enterprise systems.

Modern Java on the web has moved away from applets to frameworks like Spring, Micronaut, and Jakarta EE. These frameworks offer robust support for building RESTful APIs, microservices, and full‑stack applications with strong type safety, compile‑time checks, and a vibrant ecosystem of libraries. The original promise of portability remains relevant: Java applications can run on any operating system with a JVM, making deployment across cloud providers and on-premise servers straightforward.

Although applets are now largely obsolete, Java’s influence on web development persists. From secure backend services to Android app development, the same language that once powered interactive browser plug‑ins continues to be a cornerstone of enterprise technology stacks.

VBScript and Active Server Pages: Microsoft’s Early Web Technologies

As Microsoft entered the web arena in the late 1990s, it introduced VBScript - Visual Basic for Applications extended to the web. VBScript was tightly integrated with Internet Explorer, offering a familiar syntax for developers who had previously written desktop applications in Visual Basic. Because the language ran only in Internet Explorer, it did not cross‑browser, which limited its adoption outside the Windows ecosystem.

Complementing VBScript was Active Server Pages (ASP), a server‑side technology that allowed embedding VBScript or JavaScript code directly into HTML files. When the IIS web server processed an .asp page, it passed the request through the ASP interpreter, which executed the embedded script. This process generated a dynamic HTML document that was sent back to the client. ASP's simplicity and close integration with Windows technologies - COM objects, ActiveX, and the Windows registry - made it a powerful tool for building data‑centric web applications on Windows servers.

ASP enabled features such as session management, cookie handling, and database connectivity through OLE DB or ODBC drivers. By combining VBScript with server‑side objects, developers could create complex applications like content management systems, e‑commerce platforms, and intranets that ran natively on Windows infrastructure.

However, ASP had significant limitations. Its tight coupling to Internet Explorer and Windows restricted cross‑platform compatibility. Additionally, the language offered limited error handling and debugging capabilities compared to modern frameworks. Security vulnerabilities also emerged, as unvalidated user input could lead to injection attacks, and the use of COM objects made it difficult to sandbox code effectively.

Recognizing these constraints, Microsoft released ASP.NET in 2002. ASP.NET replaced the old interpreter with a robust, component‑based architecture that leveraged the Common Language Runtime (CLR). Developers could now write server‑side code in multiple languages - VB.NET, C#, F# - and benefit from advanced features such as strong typing, garbage collection, and a comprehensive class library. ASP.NET also introduced a more powerful page lifecycle, controls, and the ability to build reusable components with .NET’s Rich Client Library.

While VBScript and classic ASP remain in legacy systems, their principles continue to influence modern ASP.NET development. The shift from VBScript to .NET languages marked a move toward a more secure, scalable, and cross‑platform web technology stack within the Microsoft ecosystem.

PHP: The Open‑Source Alternative

PHP, short for “PHP: Hypertext Preprocessor,” began as a set of Common Gateway Interface scripts written by Rasmus Lerdorf in 1994. Its original purpose was simple: track visitor statistics on his personal website. From those humble origins, PHP evolved into a full‑featured scripting language that could be embedded directly into HTML. The key advantage was that PHP code runs on the server, generating HTML dynamically before it reaches the client.

Because PHP is interpreted, developers can write scripts that handle form submissions, query databases, manipulate files, and perform server‑side validation - all within the same file that delivers the page. Its integration with the Apache web server was straightforward, and the LAMP stack (Linux, Apache, MySQL, PHP) became a popular choice for web hosting providers in the early 2000s.

PHP’s syntax bears resemblance to C, Perl, and Java, making it approachable for many programmers. The language includes a rich set of built‑in functions for string manipulation, date handling, and regular expressions. PHP’s database abstraction layer, PDO, provides a consistent API for interacting with MySQL, PostgreSQL, SQLite, and other databases, simplifying data‑centric application development.

Security in PHP has always been a topic of discussion. Early versions had weak default configurations, but modern PHP (7.x and beyond) includes robust input filtering, prepared statements to prevent SQL injection, and improved memory management. The PHP community actively maintains a suite of security best practices, and the language’s package manager, Composer, encourages dependency isolation and version control.

Frameworks such as Laravel, Symfony, and CodeIgniter have elevated PHP from a scripting language to a full application framework. They offer MVC architecture, routing, ORM, and testing utilities, enabling developers to build scalable, maintainable systems. The widespread adoption of PHP is evident in content management systems like WordPress, Drupal, and Joomla, which power a significant portion of the web.

While some developers criticize PHP’s inconsistencies, the language’s continuous evolution - particularly the performance gains in PHP 7 and the introduction of typed properties in PHP 8 - has addressed many past shortcomings. Its open‑source nature and large community ensure that PHP remains relevant, especially for small‑to‑medium sized projects and rapid prototyping.

XML: Structured Data for the Web

eXtensible Markup Language (XML) was created to provide a flexible, platform‑independent way to describe and transport structured data. Unlike HTML, which has a fixed set of tags, XML allows developers to define custom tags that precisely match the semantics of their data. This flexibility made XML a natural choice for data interchange between heterogeneous systems.

XML’s hierarchical structure mirrors that of a tree: a root element contains child elements, which in turn can contain their own children. Attributes provide additional metadata, and character data can be nested within elements. Validation through Document Type Definitions (DTDs) or XML Schemas ensures that XML documents conform to a predefined structure, reducing errors when exchanging data.

In web development, XML served multiple purposes. First, it acted as a serialization format for server responses. APIs that returned XML allowed clients - whether browsers, mobile apps, or other servers - to parse and display data consistently. Technologies like SOAP (Simple Object Access Protocol) used XML to encapsulate messages, enabling remote procedure calls over HTTP.

Second, XML played a vital role in configuration. Many Java EE servers, web frameworks, and build tools (e.g., Maven’s pom.xml) rely on XML to describe application settings, dependencies, and deployment descriptors. This convention provided a unified way to manage complex systems without hardcoding configuration into code.

Third, XML enabled data interchange formats such as RSS and Atom, which deliver syndicated content to readers and aggregators. While JSON has largely supplanted XML for RESTful APIs due to its lighter weight and native support in JavaScript, XML still holds ground in enterprise environments where strict schema validation and namespace support are essential.

Parsing XML on the client side can be achieved with the Document Object Model (DOM) or with XMLHTTPRequest in browsers. Server‑side languages offer robust libraries - DOM, SAX, StAX for Java; ElementTree and lxml for Python; SimpleXML for PHP - to read, write, and transform XML efficiently.

Today, the proliferation of microservices and the need for data portability have driven the adoption of formats that combine XML’s expressive power with lightweight parsing, such as JSON and YAML. Nonetheless, XML remains a cornerstone for many legacy systems, document formats (e.g., DOCX, XLSX), and industry standards where strict validation and namespace resolution are required.

About the Author

Manish Sharma has been developing the web since 1996. He leads SimplyGraphix.com, a web development and advertising agency in India, building sites across real‑estate, insurance, biotech, medical, software, education, gaming, finance, and web‑portal sectors. He also runs Fontmagic.com, one of the world’s largest font archives, and Webdevelopersnotes.com, an online resource for web developers.