Showing posts with label system. Show all posts
Showing posts with label system. Show all posts

January 03, 2022

Top 20 Apache Tomcat Interview Questions and Answers

  

       Tomcat is a Java Servlet container and web server developed by the Apache Software Foundation's Jakarta project. Client browsers send queries to a web server, which the server answers to with web pages. Web servers can generate dynamic content based on the user's requests. Because it supports both Java servlet and JavaServerPages (JSP) technologies, Tomcat excels at this. Even if a free servlet and JSP engine is required, Tomcat can be utilised as a web server for a variety of applications. It can run on its own or alongside standard web servers like Apache httpd, delivering static pages while Tomcat handles dynamic servlet and JSP queries.

    Apache Tomcat is an open source Java Servlet, JavaServer Pages, Java Expression Language, and Java WebSocket implementation platform. Many firms are hiring Devops engineers, Apache Tomcat administrators, Linux Apache Tomcat jobs, and Hadoop developers at varying levels of experience. The most popular Web server is Apache, and you must be familiar with it if you plan to work as a Middleware/System/Web administrator. Apache HTTP is a free and open-source web server that runs on Windows and Linux.

 Apache Kafka Interview Questions and Answers

Ques. 1): Who is in charge of Tomcat?

Answer:

The Apache Software Foundation is the correct answer. The Apache Software Foundation is a non-profit organisation that oversees several Open Source projects.

The Apache Software Foundation's Java-based projects are referred to as Jakarta.

Tomcat is an Apache Jakarta project that manages server-side Java (in the form of Servlets and JSPs). Tomcat is the "reference" implementation of the Servlet and JSP specifications, which means that anything that runs in Tomcat should run in any compliant Servlet / JSP container.

 Apache Tapestry Interview Questions and Answers

Ques. 2): Difference between apache and apache-tomcat server?

Answer: 

Apache: Apache is mostly used to serve static content, but there are numerous add-on modules (some of which are included with Apache) that allow it to modify the content and serve dynamic content written in Perl, PHP, Python, Ruby, and other languages.

Apache is an HTTP server that serves HTTP requests.

Tomcat is a servlet/JSP container developed by Apache. It's written in the Java programming language. Although it can provide static information, its primary function is to host servlets and JSPs.

JSP files (which are comparable to PHP and older ASP files) are converted into Java code (HttpServlet), which is then compiled into.class files and run by the Java virtual machine by the server.

Apache Tomcat is used to deploy your Java Servlets and JSPs. So in your Java project, you can build your WAR (short for Web ARchive) file, and just drop it in the deploy directory in Tomcat.

Although it is possible to get Tomcat to run Perl scripts and the like, you wouldn’t use Tomcat unless most of your content was Java.

Tomcat is a Servlet and JSP Server serving Java technologies

 Apache Ambari interview Questions & Answers

Ques. 3):  What exactly is Coyote?

Answer:

Coyote is a Tomcat Connector component that acts as a web server and supports the HTTP 1.1 protocol. This enables Catalina, which is ostensibly a Java Servlet or JSP container, to additionally serve local files as HTTP documents.

Coyote monitors a specific TCP port for incoming connections to the server and transmits the request to the Tomcat Engine, which processes the request and returns a response to the requesting client.

Coyote is Tomcat's HTTP connector, which offers an interface for browsers to connect to.

 Apache Hive Interview Questions & Answers

Ques. 4): What is a servlet container?

Answer:

A servlet container is a web server component that communicates with Java servlets. The servlet container is in charge of managing servlet lifecycles, mapping URLs to specific servlets, and ensuring that the URL requester has the appropriate access privileges.

Requests to servlets, JavaServer Pages (JSP) files, and other types of files containing server-side code are handled by the servlet container. The Web container generates servlet instances, loads and unloads servlets, creates and manages request and response objects, and handles other servlet-related operations.

The web component contract of the Java EE architecture is implemented by the servlet container, which defines a runtime environment for web components that includes security, concurrency, lifecycle management, transaction, deployment, and other services.

Apache Spark Interview Questions & Answers 

Ques. 5): How Do I Can Change The Default Home Page Loaded By Tomcat?

Answer :

We can easily override home page via adding welcome-file-list in application $TOMCAT_HOME/webapps//WEB-INF /web.xml file or by editing in container $TOMCAT_HOME/conf/web.xml

In $TOMCAT_HOME/conf/web.xml, it may look like this:

    index.html

    index.htm

    index.jsp

Request URI refers to a directory, the default servlet looks for a "welcome file" within that directory in following order: index.html, index.htm and index.jsp

Apache NiFi Interview Questions & Answers 

Ques. 6): what is a difference between Apache and Nginx web server?

Answer:

Both are classified as Web Servers, but there are a few key differences. Nginx is an event-driven web server, whereas Apache is a process-driven web server.

Nginx has a reputation for being faster than Apache.

Whereas Nginx does not support OpenVMS or IBMi, Apache supports a wide range of operating systems.

Nginx is still catching up to Apache in terms of module interoperability with backend application servers.

Nginx is a lightweight web server that is rapidly gaining market share. If you're new to Nginx, you might be interested in reading some of my Nginx articles.

 Apache Ant Interview Questions and Answers

Ques. 7): How Do You Create Multiple Virtual Hosts?

Answer :

If you want tomcat to accept requests for different hosts e.g. www.myhostname.com then you must

Create ${catalina.home}/www/appBase , ${catalina.home}/www/deploy, and ${catalina.home}/conf/Catalina/www.myhostname.com

Add a host entry in the server.xml file

Create the the following file under conf/Catalina/www.myhostname.com/ROOT.xml

Add any parameters specific to this hosts webapp to this context file

Put your war file in ${catalina.home}/www/deploy

When tomcat starts, it finds the host entry, then looks for any context files and will start any apps with a context.

 

Ques. 8): In Apache Tomcat, what is Catalina?

Answer:

Once Jasper has completed the compilation, it turns JSP into a servlet, which Catalina can then manage. Catalina is a servlet container for Tomcat. It also implements all of the Java server page and servlet specs. Catalina is a Java engine embedded into Tomcat that provides an efficient environment for servlets to execute in.

 

Ques. 9): What exactly do you mean by Tomcat's default port, and can it be used with SSL?

Answer:

Tomcat uses port 8080 as its default port. Well, you can change it by editing the server.xml file in the Tomcat install directory's conf folder. By adjusting the property to the desired port connection port="8080" and then restarting Tomcat, the modifications will take effect.

Tomcat can use SSL, but it will require some configuration. You must complete the following tasks:

Generate a keystore

Then add a connector in server.xml

Restart Tomcat

 

Ques. 10): What is a mod_evasive module, and what does it do?

Answer:

Mod_evasive is a third-party module that accomplishes one simple task really well. It identifies when your site is under attack by a Denial of Service (DoS) attack and mitigates the harm that the attack causes. When a single client makes repeated requests in a short period of time, mod evasive recognises this and refuses additional requests from that client. The ban can last for a very short time because it is simply reissued the following time a request is discovered from that same host.

 

Ques. 11): Explain Directory Structure Of Tomcat?

Answer :

Directory structure of Tomcat are:

bin - contain startup, shutdown, and other scripts (*.sh for UNIX and *.bat for Windows systems) and some jar files also there.

conf - Server configuration files (including server.xml) and related DTDs. The most important file in here is server.xml. It is the main configuration file for the container.

lib - contains JARs those are used by container and Servlet and JSP application programming interfaces (APIs).

logs - Log and output files.

webapps – deployed web applications reside in it .

work - Temporary working directories for web applications and mostly used during in JSP compilation where JSP is converted to a Java servlet.

temp - Directory used by the JVM for temporary files .

 

Ques. 12): Explain How Running Tomcat As A Windows Service Provides Benefits?

Answer :

Running Tomcat as a windows service provides benefits like:

Automatic startup: It is crucial for environment where you may want to remotely re-start a system after maintenance

Server startup without active user login: Tomcat is run oftenly on blade servers that may not even have an active monitor attached to them. Windows services can be started without an active user

Security: Tomcat under window service enables you to run it under a special system account, which is protected from the rest of the user accounts

 

Ques. 13): How Do Servlet Life Cycles Work?

Answer:

The life-cycle of a typical Tomcat servlet is as follows:

Through one of its connectors, Tom-cat receives a request from a client.

This request will be processed. This request is routed through Tomcat to the proper server.

Tomcat checks that the servlet class has been loaded after the request has been forwarded to the proper servlet. If it isn't, Tomcat wraps the servlet in Java Bytecode, which is executed by the JVM and creates a servlet instance.

The servlet is started by Tomcat by invoking its init method. The servlet includes code that can inspect Tomcat configuration files and take appropriate action, as well as declare any resources it might need.

Once the servlet has been started, Tomcat can call the servlet’s service method to proceed the request

Tomcat and the servlet can co-ordinate or communicate through the use of listener classes during the servlet’s lifecycle, which tracks the servlet for a variety of state changes.

To remove the servlet, Tomcat calls the servlets destroy method.

 

Ques. 14): In Tomcat, what is the difference between a host and a context?

Answer:

In Tomcat, the host is a component. It's a network name association for the server. On the other hand, context is an element that indicates a web application that is running on a certain virtual host. Web applications are built on top of a Web Application Archive (WAR) file or a corresponding directory that contains all of the unpacked content indicated in the servlet description.

 

Ques. 15): What Is The Distinction Between A Webserver And An Application Server?

Answer:

The main distinction between a web server and an application server is that a web server can only execute web applications, such as servlets and JSPs, and has just one container, the Web container, that is used to understand and execute web applications. The application server has the ability to run Enterprise applications, i.e. (servlets, jsps, and EJBs)

it is having two containers:

Web Container(for interpreting/executing servlets and jsps)

EJB container(for executing EJBs).

it can perform operations like load balancing , transaction demarcation etc.

 

Ques. 16): Apart from Apache Tomcat, what are the different kinds of Web Servers?

Answer:

There are many web servers as mentioned below:

LiteSpeed Web Server

GWS Web Server

Microsoft IIS Web Server

Nginx Web Server

Jigsaw Web Server

Sun Java System Web Server

Lighttpd Web Server

 

Ques. 17): How to limit upload size?

Answer:

I have a web application that allows users to upload files such as word documents, pdf and so on.  How do I limit file upload by users?

You can make use of the LimitRequestBody directive to limit upload file size.

<Directory "usr/local/apache2/uploads">

LimitRequestBody 9000

</Directory>

The value assigned to the LimitRequestBody allows Apache to accept and store file uploads of 9000 bytes by users. You can adjust the value based on the requirement.

 

Ques. 18): Explain how to use WAR files to deploy a web application.

Answer:

JSPs, servlets, and their associated files are placed under Tomcat's web applications directory in the appropriate subdirectories. You can combine all of the files in the web apps directory into a single compressed file with the extension.war. A web application can be run by placing a WAR file in the webapps directory. When a web server starts up, it extracts the contents of the WAR file and places them in the proper webapps sub-directories.

 

Ques. 19): How can an Apache Service be stopped by its control script?

Answer:

The Apache Service is controlled using a script called the apachectl.

So, to stop the service, we need to run the below-mentioned commands.

#apachectl stop [for Ubuntu based system]

# /etc/inid.t/httpd.stop [for red hat based system]

 

Ques. 20): What is the purpose of the Listen property in Apache Tomcat?

Listening is very important for Apache Tomcat and the developers.

If a developer has numerous IPs on the server, we must explicitly indicate IP and PORT in the Listen Drive if we want Apache to evaluate only one of them.

For example: 10.10.10.20

 

 

November 17, 2021

Top 20 Edge Computing Interview Questions & Answers


Ques: 1). What is edge computing, and how does it work?

Answer:

With the passage of time, technology tends to become smaller and faster. As a result, previously "dumb" items such as light bulbs and door locks can now contain modest CPUs and RAM. They can perform calculations and provide information on usage. This computing enables analytics to be performed at the network's most granular levels, often known as the edge.

Edge computing puts processing power closer to the end user or the data source. In practise, this implies relocating computation and storage from the cloud to a local location, such as an edge server. Read more about edge computing in our overview.

 

Ques: 2). Is the footprint of this edge service appropriate for my needs?

Answer:

Different edge computing applications may have drastically different needs for geographic coverage and proximity. Consider the requirements of your project. Edge computer nodes could be located within or near each factory, but only for a limited number of locations.

The creator of an augmented reality programme that customers can use in stores to get real-time product ratings and pricing comparisons might want edge nodes on every street corner, or as near to that as possible.

 

Ques: 3). Why Edge Computing?

Answer:

This technique optimises bandwidth efficiency by analysing data at the edge, as opposed to the cloud, which requires data transfer from the IoT, which requires high bandwidth, making it beneficial for application in remote locations at low cost. It enables smart applications and devices to react to data practically simultaneously, which is critical in business and self-driving automobiles. It can process data without putting it on a public cloud, which assures complete security.

While on an extended network, data may become corrupt, compromising the data's dependability for companies to use. The utilisation of cloud computing is limited by data computation at the edge.

 

Ques: 4).  What are the main Key Benefits and services Of Edge Computing?

Answer:

  • Faster response time.
  • Security and Compliance.
  • Cost-effective Solution.
  • Reliable Operation With Intermittent Connectivity.

Edge Cloud Computing Services:

  • IOT (Internet Of Things)
  • Gaming
  • Health Care
  • Smart City
  • Intelligent Transportation
  • Enterprise Security

 

Ques: 5). Is there really a need for that much computation at the edge?

Answer:

Another way to phrase this question is: Which data-intensive tasks would benefit the most from network offloading? Not all applications will be eligible, and many will require data aggregation that is beyond the capability of local computing. Look for situations where processing data closer to the consumer or data source would be more efficient. These three, according to Steven Carlini, are the best prospects for edge computing.

 

Ques: 6). Is there really a need for that much computation at the edge?

Answer:

Another way to phrase this question is: Which data-intensive tasks would benefit the most from network offloading? Not all applications will be eligible, and many will require data aggregation that is beyond the capability of local computing. Look for situations where processing data closer to the consumer or data source would be more efficient. These three, according to Steven Carlini, are the best prospects for edge computing.

 

Ques: 7). How much storage should be available at the edge?

Answer:

Large volumes of data that would have been saved in the cloud will now be stored locally thanks to edge computing. While storage technology is inexpensive, management costs are not. Will the cost of keeping and managing device data at the edge justify the move? How will edge devices be protected?

Processing data at the edge, rather than uploading raw data to the cloud, may be a better way to secure user privacy. Edge computing's dispersed nature, on the other hand, renders intelligent edge devices more susceptible to malware outbreaks and security breaches.

 

Ques: 8). Why is it important to concentrate on edge computing right now?

Answer:

Edge is ripe now, thanks to new technology and demand for new applications. Consumers seek reduced latency for content-driven experiences, while businesses need local processing for security and redundancy. If you're interested in learning more about where edge computing is going, check out our article on the future of edge computing.

 

Ques: 9). What kind of apps, services, or business strategies would your edge computing platform deliver?

Answer:

Determine which workloads should run on the edge rather than in a central location, if you haven't previously, says Yugal Joshi, vice president of Everest Group. IT leaders should also look into whether any existing initiatives (such as IoT or AI) could benefit from edge processing.

 

Ques: 10). Will the organization's operating model have to alter as a result of edge computing?

Answer:

The usage of edge computing to support operational technologies is common. In such circumstances, technology leaders must determine who will own and manage the edge environment, whether greater alignment between the operating and information technology groups is required, and how performance will be monitored.

 

Ques: 11). What is the distinction between edge computing, cloud computing, and fog computing?

Answer:

Data collection, storage, and calculation are all done on edge devices in edge computing.

Cloud computing is the storing and computation of data on servers that are primarily more powerful and connected to edge devices. The edge devices transfer their data across the network to the cloud, where it is processed by a more sophisticated system.

Fog computing is a hybrid of the two approaches. The cloud servers are sometimes too far away from the edge devices for data analytics to happen quickly enough. As a result, a fog computing intermediary device is set up as a hub between two fog computing devices. This device does the computation and analytics required by the edge device.

 

Ques: 12). What role does a database play in edge computing?

Answer:

A device on the edge must be able to store and manage the data it generates efficiently. These devices have very little CPU and storage space, and they may power cycle frequently and unpredictably. A database system is the only means to store and use data in a secure manner. Additionally, the data may need to be easily transferred to a cloud system or accessed from a remote location. A database system  with SymmetricDS can provide a developer with a simple set of APIs to accomplish this.

 

Ques: 13). What is the sturdiness of this edge solution? How will the edge provider ensure that the application recovers if it fails?

Answer:

As businesses move beyond experimenting with edge computing to leveraging it for more significant applications, questions like these will become increasingly essential. To mitigate the risks of the innovative edge components, IT architects will want to use tried-and-true technologies whenever possible. Service level agreements and quality of service guarantees are important to business leaders. Even so, there will be setbacks.

 

Ques: 14). What is our long-term plan for managing edge resources?

Answer:

It's difficult enough to manage network and computer resources that are split between company data centres and the cloud. The difficulty could be amplified with edge computing.

You should inquire about what systems management resources an edge service provider provides, as well as how well-known systems management software vendors are addressing the unique aspects of edge computing.

There's also the issue of labour division: how much control will the enterprise have over how software is deployed to and updated on edge nodes? How much of that will it entrust to a third-party service provider?Will the enterprise even have the option of exercising control over the management of cloud nodes, or will the service provider consider that its own business?

 

Ques: 15). What safeguards do we have in place to avoid becoming enslaved to this cutting-edge solution?

Answer:

For the most part, open source software and open standards have prevailed in the cloud, and they're likely to win on the edge for the same reasons, according to Drobot. Open internet technologies are the most adaptable and portable, making them popular among clients as well as cloud providers who need to improve their solutions on a regular basis. He predicts that the same dynamics will apply to edge computing. The biggest exceptions so far have been related to edge computing resource metering and billing technology. Technology for managing edge computing that is specific to a particular vendor’s environment could make it harder to move your applications elsewhere.

 

Ques: 16). How might edge computing aid in the real-time visualisation of my business?

Answer:

Because data is handled in parallel across several edge nodes, edge computing allows industrial data to be processed more efficiently. Furthermore, because data is computed at the edge, delay from a round trip across the local network, to the cloud, and back is not required. Edge computing is hence well suited for real-time applications. Edge computing can assist in the prevention of equipment failure by detecting and forecasting when faults may occur, allowing operators to respond earlier. Real-time KPIs can provide decision makers with a complete picture of their system's state. Identifying which information is most valuable to receive in real-time can scope edge computing projects to focus on what’s important.

 

Ques: 17). How can I put Machine Learning to work at the edge?

Answer:

At the edge, machine learning algorithms can reduce raw sensor data by removing duplicates and other noise. Machine Learning can greatly reduce the amount of data that has to be transferred over local networks or kept in the cloud or other database systems by identifying useful information and discarding the rest. Machine learning in edge installations ensures cheaper running costs and more efficient operation of downstream applications.

 

Ques: 18). Where do you see possibilities for integrating with existing systems?

Answer:

According to a survey conducted by IDC Research, 60% of IT workers have five or more analytical databases, and 25% have more than ten. Edge computing allows these external systems to be integrated into a single real-time experience. Edge computing systems can easily consider other systems as new nodes in the system by employing bridges and connections, whereas integration has previously been a big difficulty. As a result, seeing integration opportunities early on can help you get the most out of your edge computing solution.

 

Ques: 19). What kinds of costly incidents may be avoided if I was alerted sooner?

Answer:

Edge computing architectures' real-time advantages can help minimise costly downtime and other unintended consequences. You may more effectively prioritise the desired objectives for your edge computing project by analysing which events can be the most disruptive to your organisation. Edge computing can assist identify the conditions that cause failure in real-time and enable operators to intervene sooner, whether your objective is to reduce downtime, develop an effective predictive maintenance strategy, or ensure that logistical operations are made more efficient.

 

Ques: 20). What can I do to make it more secure?

Answer:

Edge deployments are complicated, as each node adds to the vulnerability surface area. As a result, security planning is vital to the success of any edge computing project. Edge computing enables the encryption of critical data at the point of origin, ensuring an end-to-end security solution. Additional security steps can be taken by separating edge services from the rest of the programme, guaranteeing that even if one node is hacked, the remainder of the application can continue to function normally.