Web server vs ap­pli­ca­tion server: Either/or, or so much more?

There are plenty of sim­i­lar­i­ties and dif­fer­ences between a web and ap­pli­ca­tion server, but the two can also work together to produce better results when building and managing websites.

What’s the web server vs ap­pli­ca­tion server debate all about?

Networks need to be able to serve numerous requests, some of which are extensive, within a very short time and in ac­cor­dance with the latest security standards. This is only possible if the various programs work together optimally. The client-server model has proven to be a suc­cess­ful system in which tasks and services can be dis­trib­uted for smooth operation. Two possible instances within this ar­chi­tec­ture are web servers and ap­pli­ca­tion servers. They’re often confused, but despite their sim­i­lar­i­ties they also have numerous dif­fer­ences. We’ll discuss them below. First, let’s take a closer look at the two.

What’s a web server?

When you’re browsing the internet, a web server is like your permanent point of contact. Contents of all websites are stored on such a server and then made available for users. As a rule, these servers are hosted by providers who make their services available to website operators. Larger companies may have their own web server for their internet content and op­tion­al­ly their intranet. The main task of a web server is to transfer data to the client. These are static in the process.

In addition, a web server fulfills several other tasks. These include:

• HTTP caching: To better handle large amounts of data, web servers can buffer elaborate content through caching
• Com­mu­ni­ca­tion: Errors and successes are shared with the re­spec­tive browser via status codes or error pages.
• Protocol: All requests are deposited and stored in a log file.
• Security: Web servers provide en­cryp­tion HTTPS.
• Cookie man­age­ment: Cookies can be managed by web servers.
• Redirects: Web servers can redirect to another document via a rewrite engine.
• Access re­stric­tion: The web server lets you query and confirm iden­ti­ties.

What’s an ap­pli­ca­tion server?

An ap­pli­ca­tion server provides and executes programs. These include services such as au­then­ti­ca­tion, trans­ac­tions, di­rec­to­ries and databases as well as office programs, ad­min­is­tra­tion software and calendars. The client then gains access to these programs. Ap­pli­ca­tion servers are often used in the IT in­fra­struc­ture of large companies. Among other things, this avoids software com­pat­i­bil­i­ty issues, strength­ens security ar­chi­tec­ture, and improves per­for­mance.

In addition to some specific char­ac­ter­is­tics that may vary by vendor, ap­pli­ca­tion servers have explicit and implicit char­ac­ter­is­tics. The explicit features are:

• Con­nec­tion to databases and higher-level services
• Asyn­chro­nous com­mu­ni­ca­tion
• En­cap­su­la­tion of data sources
• Per­sis­tence
• Directory services

In addition, there are some implicit features such as:

• Cal­i­bra­tion
• Runtime man­age­ment
• Logging functions
• Mon­i­tor­ing
• Scal­a­bil­i­ty
• Software lifecycle man­age­ment

What are the dif­fer­ences between a web server and an ap­pli­ca­tion server?

Glancing at the special features, it becomes clear that the two server types do have things in common, but they’re also clearly dif­fer­en­ti­at­ed by area of ap­pli­ca­tion and spec­i­fi­ca­tion. We’ll show you their dif­fer­ences by comparing web servers and ap­pli­ca­tion servers.

Dif­fer­ence 1: Intended use

A web server is software or hardware that helps to access websites via the internet or intranet. Visitors make requests that are answered via the web server. An ap­pli­ca­tion server, on the other hand, is a software framework that provides clients with specific programs or access to a database.

Dif­fer­ence 2: Content

A major dif­fer­ence is the type of content handled by the two types of servers. The content that web servers provide is static. The server responds to HTTP requests and performs the functions of a website. The content that’s hosted and delivered may be, for example, text, images, JavaScript, or CSS. An ap­pli­ca­tion server, on the other hand, delivers dynamic content. It provides the business logic for apps using various protocols. These protocols can be HTTP.

Dif­fer­ence 3: Main features

There are also major dif­fer­ences in terms of main functions. The main feature of the web server is the con­sis­tent provision of HTML, PHP and ASP files for the re­spec­tive web browsers. If a user then accesses the cor­re­spond­ing web page, its contents are im­me­di­ate­ly delivered. The ap­pli­ca­tion server provides various ap­pli­ca­tions that can be used by any client in a network.

Dif­fer­ence 4: More features

Web servers can also be used for some other ap­pli­ca­tions. For example, some games, en­ter­prise ap­pli­ca­tions or data storage rely on a web server for support. In addition to its main function, the ap­pli­ca­tion server also provides web-based software and en­ter­prise-based programs.

Dif­fer­ence 5: Use of resources

A big dif­fer­ence emerges in the use of resources. Compared to a web server, an ap­pli­ca­tion server usually requires sig­nif­i­cant­ly more resources. This is due, in par­tic­u­lar, to larger files and longer processes. The data traffic is sig­nif­i­cant­ly higher when using an ap­pli­ca­tion server than a web server.

Dif­fer­ence 6: Mul­ti­thread­ing

Mul­ti­thread­ing means the si­mul­ta­ne­ous pro­cess­ing of several tasks or the parallel execution of different processes. This mode of operation is supported by the ap­pli­ca­tion server, which allows multiple requests to be processed at the same time. A web server, on the other hand, does not offer this option, instead always executing tasks one after the other.

Dif­fer­ence 7: Achi­tec­ture

The ar­chi­tec­ture of a network with a web server is much simpler. Here, a client sends a request in HTTP format directly to the web server. The server accesses a database and returns the requested files in the form of an HTTP response. The structure is com­par­a­tive­ly simple and uses the most direct paths possible.

The ap­pli­ca­tion server, on the other hand, is located between the web server and the database. In this case, the client also sends an HTTP request to the web server. This sends it on to the ap­pli­ca­tion server, which in turn converts it into a servlet request and sends it to the database. There the request is processed and sent back to the ap­pli­ca­tion server. The ap­pli­ca­tion server passes the response to the web server, which converts it back into HTTP format and passes it to the client. Dynamic content can also be made available in this way.

Dif­fer­ence 8: Provider

The most popular and widely used web server providers include:

• Apache HTTP Server
• Caddy
• Cherokee
• LiteSpeed Web Server
• Microsoft IIS
• NGINX

The most popular ap­pli­ca­tion servers are:

• Apache Tomcat
• IBM CICS
• LiteSpeed Web Server
• NGINX
• Oracle Web Logic
• Red Hat JBoss En­ter­prise Ap­pli­ca­tion Platform
• Wildfly

There are com­mer­cial and open-source solutions for both web and ap­pli­ca­tion servers.

Can the two servers work together?

Although there are some major dif­fer­ences in the ar­chi­tec­ture of web servers and ap­pli­ca­tion servers, they can be used together. If a website plans to offer static and dynamic content, it’s worth combining the two server types. The web server forwards the requests to the ap­pli­ca­tion server and returns its responses to the client. So, an either-or decision is not always necessary. Some ap­pli­ca­tion servers already contain web servers.

Web server vs. ap­pli­ca­tion server: Which one is the right choice?

Since the web server is primarily re­spon­si­ble for the con­tin­u­ous and rapid display of website content, and the ap­pli­ca­tion server is primarily re­spon­si­ble for the business logic and avail­abil­i­ty of various ap­pli­ca­tions, you may be asking yourself which server type is most suitable for your website.

If you only want to include static content on your website, go with a web server. If you have dynamic content, use a com­bi­na­tion of a web server and an ap­pli­ca­tion server.

However. the number of websites only dis­play­ing static content is dwindling and such websites may become obsolete in the future. The bound­aries between a web server and ap­pli­ca­tion server are also becoming in­creas­ing­ly blurry. It makes sense then to regard web servers and ap­pli­ca­tion servers as two options for tailoring your website instead of as opponents. To meet the demands of modern websites, popular providers such as Apache or NGINX already offer a com­bi­na­tion of both server types.