20 Application Server Interview Questions and Answers

An Application Server is a software program that provides the infrastructure and services for a network application. When interviewing for a position that requires knowledge of Application Servers, expect questions about your experience and skills working with this software. In this article, we review some of the most common Application Server interview questions and provide tips on how to answer them.

Application Server Interview Questions and Answers

Here are 20 commonly asked Application Server interview questions and answers to prepare you for your interview:

1. What is an application server?

An application server is a type of server that is designed to host applications. Application servers typically provide a platform for running applications, as well as a set of tools and services that can be used by developers to create, deploy, and manage their applications.

2. Can you explain the difference between a Web Server and an Application Server?

A Web server is designed to serve HTML pages and other static content to clients. An application server, on the other hand, is designed to run applications and provide dynamic content to clients. In order to do this, application servers typically provide a runtime environment, as well as a set of services that applications can use, such as database access, security, and so on.

3. What are some of the most popular application servers in use today?

Some of the most popular application servers in use today include Apache Tomcat, JBoss, and Websphere.

4. What’s your understanding of custom applications on top of JBoss EAP? How would you deploy them?

A custom application on top of JBoss EAP is an application that has been specifically designed to work with the JBoss EAP application server. In order to deploy a custom application on top of JBoss EAP, you will need to first ensure that the application is compatible with the application server. Once you have verified compatibility, you can then use the JBoss EAP management console to deploy the application.

5. What does it mean to “load balance” an application server?

Load balancing is a technique used to distribute workloads evenly across a network of computers, servers, or other resources. By distributing the workload in this way, it helps to ensure that no single resource is overwhelmed by the demand, and that overall performance is improved.

6. What are the main features of an application server?

The main features of an application server are its ability to host applications and provide access to them, as well as its ability to manage and monitor the performance of those applications. An application server will also typically provide a number of other features and services that are designed to make it easier to develop, deploy, and manage applications.

7. Can you describe how you might go about troubleshooting issues that occur when using an application server?

When troubleshooting issues with an application server, the first step is to identify where the problem is occurring. Is the issue with the application server itself, or with the applications that are running on the server? Once you have identified the source of the problem, you can then begin to look at log files and other information to try to pinpoint the cause of the issue. If the problem is with the application server itself, then you will need to contact the vendor for support.

8. Can you explain what JVM heap size is? How do you configure it for an application server?

JVM heap size is the amount of memory that the Java Virtual Machine will use for its heap. This can be configured when starting up the application server. For example, to set the JVM heap size to 512 MB, you would use the -Xmx512m flag.

9. What is the relationship between JDBC, Java Messaging Service (JMS), and transactions?

JDBC is a Java API that allows Java programs to access databases. JMS is a Java API that allows Java programs to send and receive messages. Transactions are a way to ensure that a set of database operations are all completed successfully, or all rolled back if any one of them fails.

10. What does it mean to say that an application server is thread safe?

A thread safe application server is one where multiple threads can safely execute at the same time. This means that the application server must be designed in such a way that no two threads will interfere with each other’s execution. This can be achieved through a variety of means, such as by using locks or by designating certain areas of code as being off-limits to concurrent execution.

11. What are the differences between Apache Tomcat, Glassfish, Weblogic, and JBoss?

Apache Tomcat, Glassfish, Weblogic, and JBoss are all application servers. They are all used to deploy and run Java applications. However, they each have their own unique features and capabilities.

Apache Tomcat is an open source application server that is lightweight and easy to use. Glassfish is also an open source application server that is more robust and has more features than Tomcat. Weblogic is a commercial application server that is used by large enterprises. JBoss is an open source application server that is similar to Weblogic in terms of features and capabilities.

12. How much experience do you have with Oracle WebLogic?

I have worked with Oracle WebLogic for about two years now. In that time, I have become quite familiar with its various features and capabilities. I have used it to deploy and manage a number of web-based applications, and I have also used it to create and configure web services. Overall, I have found it to be a very reliable and robust application server.

13. Can you explain what a resource adapter is?

A resource adapter is a software component that allows an application server to communicate with an external resource. This could be a database, a messaging system, or any other type of system that the application needs to interact with. The resource adapter handles all of the communication between the application server and the external resource, making it easier for the application to access the data it needs.

14. Which middleware technologies have you worked with?

I have worked with a number of middleware technologies, including Apache Tomcat, JBoss, and WebLogic. I have also worked with a number of application servers, such as WebSphere and GlassFish.

15. How can you find out which processes are running on an application server?

You can use the ps command to find out which processes are running on an application server.

16. What are some common security problems associated with an application server?

One common security problem is that application servers can be used to launch denial of service attacks. This is because they can be used to generate a large amount of traffic very quickly. Additionally, application servers can be used to host malicious code that can then be used to attack other systems. Finally, application servers can be used to bypass firewalls and gain access to internal networks.

17. What types of authentication methods are typically supported by an application server?

The most common authentication methods supported by application servers are Basic Authentication and Form-based Authentication. Basic Authentication is the simplest form of authentication, and typically just involves sending a username and password with each request. Form-based Authentication is a bit more complex, and involves the server sending a login form to the client, which the client then submits with their credentials.

18. What is clustering? Have you ever used it with an application server?

Clustering is a method of horizontally scaling an application server by adding additional servers to a group. This allows for increased capacity and improved availability, as each server can take on a portion of the load. I have used clustering with an application server in the past, and it was a great way to improve performance and ensure that the server was always available.

19. What is XA transaction?

XA transaction is a distributed transaction that involves two or more resource managers, such as databases, message queues, or web services. XA transaction ensures that all the resource managers involved in the transaction either commit or roll back the changes, so that the data remains consistent.

20. What is the maximum number of threads allowed per servlet container?

The maximum number of threads allowed per servlet container is typically 200, but this can vary depending on the application server being used.