Differences between Application Server and Web Server
Contents
Web server vs. application server
Web servers and application servers are functional components of network infrastructure that deliver content to end users. While their roles frequently overlap in modern software stacks, they differ in the type of content they serve and the protocols they support. A web server primarily manages HTTP requests to deliver static content, such as HTML pages, CSS files, and images. An application server provides the business logic for software applications, often managing state, transactions, and database connections to generate dynamic content.[1]
Functionality and architecture
The primary function of a web server is to store, process, and deliver web pages to clients. When a user enters a URL in a browser, the browser sends an HTTP request to the server. The web server locates the requested file on its local disk or storage and sends it back to the browser. Examples of standalone web servers include Apache HTTP Server and Nginx.
Application servers extend this capability by providing a runtime environment for server-side code. They are designed to handle complex operations that go beyond simple file retrieval. An application server might manage a pool of database connections, handle user authentication, or execute asynchronous tasks. Because application servers often include a built-in web server component, they can handle HTTP requests directly, though they are frequently placed behind a dedicated web server in a three-tier architecture to improve security and load balancing.[2]
Comparison table
| Category | Web server | Application server |
|---|---|---|
| Primary content | Static content (HTML, CSS, JS, images) | Dynamic content and business logic |
| Protocols | Primarily HTTP and HTTPS | HTTP, HTTPS, RPC/RMI, IIOP, and FTP |
| Resource usage | Low to moderate; optimized for high concurrency | High; requires more CPU and memory for processing |
| Multi-threading | Often uses event-driven or simple thread pools | Supports heavy multi-threading and transaction management |
| Use case | Serving simple websites or front-end assets | Enterprise applications and complex data processing |
| Examples | Apache HTTP Server, Nginx, Microsoft IIS | GlassFish, Red Hat JBoss (WildFly), WebSphere |
Integration and overlap
The distinction between these two server types has become less rigid over time. Many modern web servers, such as Internet Information Services (IIS), include features that were traditionally reserved for application servers. Conversely, application servers like Apache Tomcat are frequently used as standalone web servers for small to medium-scale deployments.
In a typical enterprise deployment, a web server acts as a "reverse proxy." It receives the initial request from the internet, handles SSL termination, and serves static files. If the request requires data processing—such as logging into an account or searching a database—the web server forwards the request to the application server. This separation allows administrators to scale the web tier and application tier independently based on traffic demands.[3]
