Development hiring managers and potential interviewees may find these sample CSS proficiency interview QAs and code snippets useful. In this tutorial, we have listed the 50 most popularly asked Selenium interview questions including Selenium WebDriver interview questions. The answers provided here. Download absolutely free Basic Networking JOB interview questions and answers guide in PDF format. Free download of Python interview questions and answers ebook that contains 100 questions and answers for programmers. Purple1/v4/9a/52/8d/9a528dac-b4d4-774e-a054-52c8fa3ed620/source/1200x630bb.jpg' alt='Html Css Javascript Interview Questions And Answers Pdf Free Download' title='Html Css Javascript Interview Questions And Answers Pdf Free Download' />Software Scalability Questions Answers for Architect Interview. Web applications scalability is a common problem most of the web architect face. Any internet facing web application may require to be highly scalable due to heavy load of traffic. Now a days, developing a smart web application is much more than creating dynamic Web pages. Irrespective of programming languages like Java, PHP,. NET, Python, Ruby or others, these challenges are faced by software architects everyday. If you are a software tester looking for the job of test automation or testing, you are at the right place. We have listed over 50 Selenium interview questions to. As the web is growing, our need of building larger and more scalable applications is also becoming more important. In this decade, lot of distributed web applications are being developed that can utilize the resources from multiple machines, by separating the application functionality into manageable group of tasks that can be deployed in a distribute systems. British Dance Edition London 2012 there. There are numerous benefits to dividing applications this way, some of the most important are re usability, scalability, and manageability. 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What Do You Mean By High Availability Having better service capacity with high availability and low latency is mission critical for almost all businesses. Availability means the ability of the application user to access the system, If a user cannot access the application, it is assumed unavailable. High Availability means the application will be available, without interruption. Achieving high availability for a application is not always a easy task. Using redundant server nodes with clustering is a common way to achieve higher level of availability in web applications. Availability is commonly expressed as a percentage of uptime in a given year. What Is Scalability Scalability is the ability of a system, network, or process to handle a growing amount of load by adding more resources. The adding of resource can be done in two ways. Scaling Up. This involves adding more resources to the existing nodes. For example, adding more RAM, Storage or processing power. Scaling Out. This involves adding more nodes to support more users. Any of the approaches can be used for scaling upout a application, however the cost of adding resources per user may change as the volume increases. If we add resources to the system It should increase the ability of application to take more load in a proportional manner of added resources. An ideal application should be able to serve high level of load in less resources. However, in practical, linearly scalable system may be the best option achievable. Poorly designed applications may have really high cost on scaling upout since it will require more resourcesuser as the load increases. What Is A Cluster A cluster is group of computer machines that can individually run a software. Clusters are typically utilized to achieve high availability for a server software. Clustering is used in many types of servers for high availability. App Server Cluster. An app server cluster is group of machines that can run a application server that can be reliably utilized with a minimum of down time. Database Server Cluster. An database server cluster is group of machines that can run a database server that can be reliably utilized with a minimum of down time. Why Do You Need Clustering Clustering is needed for achieving high availability for a server software. The main purpose of clustering is to achieve 1. A typical server software can be running on one computer machine and it can serve as long as there is no hardware failure or some other failure. By creating a cluster of more than one machine, we can reduce the chances of our service going un available in case one of the machine fails. Doing clustering does not always guarantee that service will be 1. However it in not very likely in case you have many machines and they are located at different location or supported by their own resources. What Is Middle Tier Clustering Middle tier clustering is just a cluster that is used for service the middle tier in a application. This is popular since many clients may be using middle tier and a lot of heavy load may also be served by middle tier that requires it be to highly available. Failure of middle tier can cause multiple clients and systems to fail, therefore its one of the approaches to do clustering at the middle tier of a application. In java world, it is really common to have EJB server clusters that are used by many clients. In general any application that has a business logic that can be shared across multiple client can use a middle tier cluster for high availability. What Is Load Balancing Load balancing is simple technique for distributing workloads across multiple machines or clusters. The most common and simple load balancing algorithm is Round Robin. In this type of load balancing the request is divided in circular order ensuring all machines get equal number of requests and no single machine is overloaded or underloaded. The Purpose of load balancing is to. Optimize resource usage Avoid overload and under load of any machines. Achieve Maximum Throughput. Minimize response time. Most common load balancing techniques in web based applications are. Round robin. Session affinity or sticky session. IP Address affinity. What Is Sticky Session session Affinity Load Balancing What Do You Mean By session Affinity Sticky session or a session affinity technique another popular load balancing technique that requires a user session to be always served by a allocated machine. Why Sticky Session In a load balanced server application where user information is stored in session it will be required to keep the session data available to all machines. This can be avoided by always serving a particular user session request from one machine. How It Is Done The machine is associated with a session as soon as the session is created. All the requests in a particular session are always redirected to the associated machine. This ensures the user data is only at one machine and load is also shared. In Java world, this is typically done by using jsessionid cookie. The cookie is sent to the client for the first request and every subsequent request by client must be containing that same cookie to identify the session. What Are The Issues With Sticky Session There are few issues that you may face with this approach. The client browser may not support cookies, and your load balancer will not be able to identify if a request belongs to a session. This may cause strange behavior for the users who use no cookie based browsers. In case one of the machine fails or goes down, the user information served by that machine will be lost and there will be no way to recover user session. What Is IP Address Affinity Technique For Load Balancing IP address affinity is another popular way to do load balancing. In this approach, the client IP address is associated with a server node. All requests from a client IP address are served by one server node. This approach can be really easy to implement since IP address is always available in a HTTP request header and no additional settings need to be performed.