What Is an Application Server?

ServerWatch content and product recommendations are editorially independent. We may make money when you click on links to our partners. Learn More.

Applications come in all shapes, sizes, and use cases. In a world where we rely on a host of critical business processes, application servers are the high-powered computers providing application resources to users and web clients.

Application servers physically or virtually sit between database servers storing application data and web servers communicating with clients. App servers and akin middleware are the operating systems supporting an application’s development and delivery. Whether it’s a desktop, mobile, or web app, application servers play a critical role in connecting a world of devices.

We look at how application servers fit into a network’s service architecture, how app servers support web servers, native applications, and mobile apps, and the current state of application servers in the 2020s.

Application server terminology

Application server’s role in service architecture

When application users, be it staff or web clients, request access to an application, the application server often does the heavy lifting on the backend to store and process dynamic application requests.

Why Do We Need Application Servers?

Billions of web clients make HTTP requests every day, expecting instant access to you-name-the-app. Headspace during the morning routine, Google Docs for the extensive report, Twitter during a coffee break, no matter the application in use, it’s being pulled from an application server and delivered via a web server.

Web servers are responsible for serving web clients HTTP requests with HTTP responses. Unlike app servers, the web server design is light enough to process static data requests for multiple applications (or websites) while maintaining security. Dynamic requests, often in the form of applications, require additional assistance.

Application servers optimize traffic and add security

To achieve optimal web server agility, managing both HTTP requests from web clients and passing or storing resources from multiple websites doesn’t work. Application servers fill this gap with a high-powered design built for handling dynamic web content requests.

Application servers also provide program redundancy and an added layer of security. Once deployed between a database and web server, the job of preserving and duplicating application architecture across the network is more feasible. The additional step between potential malicious web communications and the crown jewels in the database server adds an extra security layer. Because application servers can process business logic requests, an attempted SQL injection is also that much harder.

Organizations can further protect their data with a reverse proxy server positioned in front of their databases. Proxy servers and VPNs can do wonders for anonymizing and encrypting communication to protect users and company data.

How Do Application Servers Work?

Like most servers today, application servers contain features for security, transactions, services, clustering, diagnostics, and databases. Where application servers deviate is their ability to process servlet requests from a web server.

In the above image, we show the general flow for web application servers:

1. The client opens a browser and requests access to a website
2. The web server receives the HTTP request and responds with the desired webpage
3. The web server handles static data requests, but the client wants to use an interactive tool
4. As a dynamic data request, the web server transfers the request to an application server
5. The application server receives the HTTP request and converts it into a servlet request
6. The servlet reaches the database server, and the app server receives a servlet response
7. The app server translates the servlet response into HTTP format for client access

Upon receiving a servlet request from a web server, the application server processes the request and responds to the web server via servlet response . Because application servers primarily work with business logic requests, the web server translates the servlet response and passes an HTTP response accessible to the user.

Application Server vs. Web Server

Application servers in the 2020s

The application server market expects to grow at a CAGR of 13.2% , rising from near $17 billion in 2020 to $41 billion in 2026. Continued growth is no surprise as internet connectivity and reliance on applications grow.

The migration to cloud platforms and services and the boom of IoT devices are two key drivers in the modern application infrastructure and middleware market. Add to this a movement toward BYOD policies and a remote workforce dependent on increased connectivity and operational efficiency. There’s no mistaking the value assigned to these powerful modules and their role in serving clients with application resources.

Application Server Vendors

Application servers: A web server’s best friend

Application servers are critical to today’s interconnected demands. Enterprises ultimately are beholden to client interests, and without a scalable and stable connection to application resources, modern customers run for the hills.

Application servers take on the role of connector and best friend for web servers. When web servers have a client request that’s too much to bear, app servers make it possible to keep communication seamless with dynamic web content.

Featured Partners: Server Management Software

BDRSuite

BDRSuite offers comprehensive server management capabilities, providing oversight of backup and disaster recovery operations on servers and hosts within your environment. Effortlessly protect your critical data across diverse environments, including Virtual, Physical, Cloud workloads, and SaaS applications. BDRSuite's robust server management features ensure seamless monitoring, management, and protection of your valuable data.