Web Server vs. Application Server: What's the Difference?

Planning to develop and deploy an application but unsure where to start? Whether you’re new to software engineering or managing a team of developers for the first time, you’ve likely heard you need a server—but what kind? Aren’t all servers essentially the same? 

Not exactly. Servers play specialized roles in hosting and running applications, with web servers and application servers serving distinct purposes. In this post, we’ll explore what each does, how they differ, and help you decide which one is right for your project. 

A server’s a server, right? Well, yes and no. 

In general, a server is a central repository where information, programs, services and other resources are held and can be accessed by other devices (clients) in the same network. Both web and application servers meet this description and offer similar functionalities to this end. However, while a web server delivers web content, an application server deals with application operations performed between users and back-end business applications of the organization. Let’s have a closer look. 

Web Server vs. Application Server: An Overview  

Architecture and Processing  

While a web server is designed to process and deliver static resources quickly, responding to each HTTP request with pre-generated content, an application server typically takes a more complex approach, dynamically generating responses by executing business logic and interacting with databases. 

In practice, this means that a web server should use minimal resources to handle a high number of simultaneous connections. Also, it operates on event-driven or asynchronous models to achieve high concurrency with low overhead. Conversely, an application server generally utilizes more substantial resources and leverages multi-threaded or pooled-thread models to handle resource-intensive processing with high efficiency. 

Resource Management  

A web server is optimized for minimal memory usage and straightforward threading approaches, ensuring fast delivery of static content. It uses lightweight threading models that are optimized for handling many simultaneous connections with minimal resource use. In addition, a web server typically relies on asynchronous or event-driven mechanisms to handle large volumes of HTTP requests efficiently. 

In contrast, an application server manages resource-intensive processes, utilizing more robust threading approaches, such as thread pooling. Connection pooling is also key, as it helps to efficiently reuse connections to databases or external services. 

Protocol Support 

When it comes to protocols, web server technology has been traditionally focusing on HTTP/HTTPS for web content delivery, application server solutions have been mastering their support for a broader range of communication protocols. These include Simple Object Access Protocol (SOAP) and Representational State Transfer (RESTful) web services for interoperability, Remote Method Invocation (RMI) for object-level interactions in Java, as well as robust messaging systems such as Java Message Service (JMS) for asynchronous communications.  

The lines in what protocols each technology supports have been blurring, tough. Nowadays, an increasing number of application servers not only incorporate web server capabilities but use HTTP and other protocols to interface with web servers. 

Development Framework  

A web server is limited to serving content generated by external applications, acting primarily as intermediaries for static and pre-generated resources. As such, it does not natively provide tools for developing or running complex backend services. 

In contrast, an application server is a robust development platform that offers integrated tools and environments for deploying, managing and scaling enterprise-grade applications. For instance, an application server that is based on Jakarta EE, such as Payara Server, leverages a suite of APIs, tools and integrations. These support tasks like database interactions, transaction management and security integration to offer developers a development framework that enables them to create sophisticated business logic, run dynamic content workflows and ensure seamless integration with other services.  

What Is an Application Server?  

An application server provides a comprehensive platform for running business applications and it is typically used for hosting applications that require dynamic, data-driven content. It executes backend logic, processes data, and facilitates complex workflows, often coordinating with web servers to serve dynamic content. It handles tasks such as transaction processing, security, resource pooling and database interaction. An example of an application server is Payara Server, which is a robust enterprise-grade application server that is designed for Jakarta EE applications. 

If you think you never use application servers, you are wrong. Suppose you want to use an application on your workstation - it could be a spreadsheet editor, a word processor or anything else. You interact with a graphical user interface to open the application, e.g. to insert your login details. When you do that, a request is sent to the application server to provide access to the application to your device (client). After receiving the request, the application server generates a response to the client’s request. In this case, the response would be access to the application you want to use. This is sent to your device, and once it is received, you can then use the application. 

Now consider the number of people in your team and the whole organization that need to access a specific application in a typical workday. The number of requests can be extremely high, and the application server is designed to handle all these at once. It can do that through load balancing. In addition, an application server is built to have a high fault tolerance, so that the server can function as normal if any issue occurs. 

Key Features:

• Database Connectivity: Offers seamless and robust database integration for efficient data management. 
• Session Management: Advanced user session handling help deliver a positive and personalized user experience. 
• Transaction Support: Meet atomicity, consistency, isolation and durability (ACID) principles to offer ACID compliance while providing robust transaction processing. 
• Security Features: Provides enterprise-grade authentication, authorization and encryption to ensure cyber resilience. 
• Middleware Services: Provides comprehensive integration with other middleware solutions to support complex workflows.
• Clustering: Designed to deliver high availability and load balancing for mission-critical applications. 

To learn more about what an application server is and what it offers, read our blog post here.

What Is a Web Server? 

A web server is a computer program or device that hosts webpages and serves web content. As such, it offers a centralized platform to host and manage websites. A web server provides web functionalities by handing HTTP requests from clients, delivering static content like HTML, CSS and images directly to clients. Two well-known and widely used web servers are Nginx and Apache. 

How does a web server work, in practice? Take any website you want to visit. When you type the website address in a web browser, it generates an HTTP request that will be sent to the web server. On the web server, your request (the client request) is received, and the specific HTML page is retrieved. The web server responds by displaying the web page you want to see on your device. 

Key Features:

• HTTP Processing: Handles solely HTTP/HTTPS requests and responses but does so with high efficiency.
• Static Content Delivery: Optimized for serving static files quickly. 
• Caching: Implements advanced caching mechanisms to maximize content delivery speed. 
• Virtual Hosting: Supports hosting multiple websites on the same server. 
• Basic Security: Provides only SSL/TLS encryption for secure communication. 
• Load Management: Typically limited load balancing, as it is only used to manage traffic efficiently. 

Differences Between Web Servers and Application Servers 

Primary Function 

The key purpose of a web server is to serve content hosted on websites by acting as the interface between the browser (client) and the server, handling HTTP/HTTPS requests and delivering requested files, data or other pieces of information. As such, a web server processes requests and responses with high efficiency. Even more, it does so with minimal resource consumption. 

Conversely, the role of an application server extends beyond merely responding to requests, as it is designed to execute and manage backend business logic and workflows for enterprise-grade applications. This means that an application server, such as Payara Server, is a platform for deploying, running and scaling applications that require business logic.  

It serves dynamic content by processing requests that involve database interactions, complex algorithms and middleware services. Also, an application server handles activities such as resource pooling, transaction management and session handling. To support all these resource-intensive activities, an application server has a greater capacity and utilizes more resources. 

Content Type 

Web servers are typically designed for the quick delivery of static content, such as HTML, CSS, JavaScript, and images, whereas application servers, such as Payara Server, support a wide range of applications. In particular, they perform complex business operations and generate dynamic content by executing business logic, interacting with databases and performing other back-end processing. Examples of dynamic content handled by application servers include personalized dashboards or user-specific data retrieved from databases, dynamic forms and reports generated by backend logic as well as complex workflows, such as e-commerce checkouts or booking systems, involving multiple layers of processing. 

As web servers are well suited for static content while application servers are designed to handle dynamic content, many production environments combine the two. More precisely, they have web server acting as reverse proxy to application servers. In practice, this means that a web server interprets page requests and server any static contents. It also identifies dynamic content requests, which are forwarded to the application server. For example, a number of projects combine Payara Server in conjunction with dedicated Apache or Nginx web servers in production environments.  

Beside the combination of web and application servers, current trends involve more sophisticated web servers, which can support plug-ins for scripting languages, such as ASP, JSP, PHP and Perl. As a result, such solutions can generate dynamic content based on server-side logic. Simultaneously, a growing number of application servers go beyond incorporating web servers or their capabilities. In fact, they can use HTTP and other protocols to interface with web servers. 

Performance and Scalability  

A web server is designed for high-speed, lightweight static content delivery with minimal overhead. It typically handles predictable content demands from websites. Scalability can be supported by adding more servers (horizontal scaling) to handle higher traffic loads without significantly increasing complexity. 

An application server, like Payara Server, is built for performance under scalability-intensive scenarios. As such, it relies on advanced resource management techniques to withstand high user loads while maintaining uptime and application’s reliability. In addition, an application server is designed to scale both horizontally, by adding more servers, and vertically, by increasing resources on existing servers. This flexibility gives an application server the ability to effectively handle dynamic, resource-intensive workflows. In effect, by being able to distribute tasks across multiple nodes in a cluster, an application server is ideal for enterprise applications with unpredictable and demanding performance requirements. 

While the theoretical distinctions between web and application servers regarding performance and scalability are clear, the boundaries often blur in practice. In fact, many modern web applications use reverse proxy, clustering, redundancy, load balancing and other services that are typically associated to application servers to improve performance and reliability.  

Similarly, an application server like Payara Server enables real-time, bi-directional communication between clients and servers via WebSockets, a capability often associated with modern web servers. This is particularly useful for applications requiring low-latency updates, such as chat apps or live dashboards. 

Security and Middleware Support  

When it comes to cybersecurity, a web server primarily focuses on implementing basic security measures, such as SSL/TLS encryption, to secure communications over HTTP and HTTPS. These measures ensure data integrity and protection against common threats, like eavesdropping and man-in-the-middle attacks. However, their functionality is often limited to securing static content and ensuring safe transmission protocols. 

An application server needs to provide a much more comprehensive suite of security features to effectively support enterprise applications. These include advanced authentication methods, such as Single Sign-On (SSO) and OAuth, role-based access control (RBAC), as well as robust authorization mechanisms. For example, applications using Payara Server as their application server can rely on a number of authentication mechanisms, such as OpenID, OAuth 2.0, Yubikey and JSON Web Token. 

In addition, as an application server integrates with middleware systems, it must offer features like encryption for sensitive data, intrusion detection systems and compliance with relevant standards, such as the EU’s GDPR or the US’ HIPAA. 

Conclusions 

You’ve reached the end of our comparison, so you should now be able to understand the key differences between web servers and application servers. By understanding the capabilities and strengths of each, you can select the most suitable solution for your project.  

This overview serves as a starting point. In effect, we highlighted areas where the demarcation between the two technologies is blurring. For example, modern web servers are often enhanced with scripting capabilities to support dynamic content, while application servers frequently integrate web server functionalities to streamline deployment and performance. In addition, in many cases, a combination of both servers is ideal, with a web server acting as a reverse proxy and serving static content while delegating dynamic processing to the application server. 

Ready to advance your application server expertise? Download Payara Platform Community for free to begin experimenting.