What are application servers?

To provide software to a client in a network, an application server is a good choice for security and compatibility reasons. Disadvantages of an application server include additional costs and more serious consequences when bugs or other problems occur.

What is an application server used for?

In ever larger systems, you need solutions that can shoulder data volume while still maintaining the desired speed and serving access volume. In a client-server network, an application server can be one such solution. An application server usually hosts different application programs and makes them available to clients. To do this, it uses server-side business logic to generate dynamic content and serve it to a client. Typical examples of software found on an application server include office programs, address management, corporate calendars and database access. Sensitive processes such as transactions or authentications can also be carried out via an application server.

What are the features of application servers?

Application servers offer various features to simplify and improve processes. A distinction is made between explicit and implicit features. In addition, there are other features that are more or less pronounced depending on the type of application server. However, common features include:

Explicit features

• Encapsulation of data sources
• Interfaces to other higher value services
• Asynchronous communication
• Preservation of persistence
• Directory services
• Standards for the connection of databases

Implicit features

Using a system with an application server creates some implicit features that can provide benefits for all users. These include:

• Better scalability without additional modification of individual applications
• Monitoring
• Logging functions
• Calibration options
• Runtime management
• Software lifecycle management through patching, upgrading, delivery and deployment

How does an application server work?

To better understand the general function of an application server, it’s important to first understand its place within a network. It ranks between individual clients and the database. It receives HTTP requests and responds to them, but it can also issue servlet requests and process the corresponding responses. This is one of the main differences between an application server and a web server. We elaborate on how the two models differ beyond that in our comparison of web servers and application servers. An application server works together with a web server in the following manner:

1. A user wants to visit a website. They open a browser and navigate to the website.
2. The HTTP request is sent to the web server that processes the request and returns the requested website to the client. This works as long as they’re static requests.
3. If an interactive tool is used instead, the procedure is the same, but the web server won’t output the response directly. Instead, it’s forwarded to the application server.
4. The application server receives the HTTP request and converts it into a servlet request.
5. It’s forwarded to the database.
6. The database server processes the request and sends a servlet response back to the application server.
7. In the final step, the application server sends the servlet format to the web server. This converts the response to HTTP and makes it available to the client.

What are the advantages and disadvantages of application servers?

If you’re thinking about using an application server, it’s worth taking a look at the advantages and disadvantages of such servers. The table below provides an overview:

What are the advantages of application servers?

An application server offers numerous advantages. They include:

Compatibility

By installing an application server in your network, you ensure all clients work with the same software version. As a result, all exchanged and stored data is compatible. If you do without an application server, problems may arise due to missed updates or outdated software.

Security

The implementation of an application server can be advantageous for security reasons. For example, it prevents a direct connection between a website and its own database. Malware attacks such as SQL injection programs can often be prevented.

Performance

Application servers can improve overall performance. Performance improvements are particularly noticeable for large and/or frequently used software. Scaling options can help to improve performance as well as bundle and control access to the database.

Configuration

Centralization via an application server means configuration doesn’t have to be performed on each individual device. This simplifies configuration and saves time and resources.

Scalability

Due to numerous connection possibilities with the database, higher scalability is possible. This also ensures greater flexibility for users.

What are the disadvantages of application servers?

However, there are a few disadvantages when using an application server. The following are worth mentioning:

Additional costs

Installation and maintenance of an application server cost money and time. You should carefully consider whether the implementation is necessary. If this is the case, costs should be considered.

Possible delays

Delays may occur during the deployment of an application server. This is especially true if the installation is performed behind a firewall.

Demanding programming

Programming requirements are higher for an application server. A little experience and prior knowledge are therefore advantageous.

Bandwidth

When several large applications are used simultaneously and multiple users access them, this can have a negative impact on speed and overall performance.

Impact of problems and bugs

While bundling is an advantage of using an application server, problems and bugs are much more pronounced as a result. Since numerous clients depend on a single source, problems with one piece of software affect several participants. Solutions for such problems are usually a bit more complicated.

What are examples of application servers?

You can choose from numerous different application servers. The best-known and most popular vendors and models include:

• Apache Geronimo: Suitable for Java EE
• Apache Tomcat: For Servlets and JavaServer Pages (JSP)
• ColdFusion: The oldest application server
• GlassFish: Open-source solution for Java EE
• Jetty: Servlet and JSP container
• Resin: For Java and PHP5
• WEBrick: Solution based on Ruby
• Zope: An application server based on Python