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Ans. In AWS Lambda we can run a function in synchronous or asynchronous mode. In synchronous mode, if AWS Lambda function fails, then it will just give an exception to the calling application. In asynchronous mode, if AWS Lambda function fails then it will retry the same function at least 3 times.If AWS Lambda is running in response to an event in Amazon DynamoDB or Amazon Kinesis, then the event will be retried till the Lambda function succeeds or the data expires. In DynamoDB or Kinesis, AWS maintains data for at least 24 hours.
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Ans. JSON is "JavaScript Object Notation", primarily used for client-server or server-server communication. Its a much lighter and readable alternative to XML. JSON is language independent and is easily parse-able in all programming languages.
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Ans. Tomcat is a web server and a Servlet container. It is often used as an application server for web-based applications but does not include the complete suite of capabilities that a Java EE application server would supply.
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LikeDiscussCorrect / Improve  tomcat   j2ee   web server   application server   build management
Q9. Example of Observer Design Pattern ?
Ans. Listeners.
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Ans. In terms of compute options and configurations, Reserved Instances and On Demand instances are the same. The only difference between the two is that a Reserved Instance is one you rent (reserved) for a fixed duration, and in return you receive a discount on the base price of an On Demand instance.
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Ans. We can create API gateway and give the name of lambda function in order to be linked with lambda function, deploy the API and whenever request will be made from API it will directly be linked to lambda function to perform further process.
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Ans. Just like people , AWS resources too have execution roles or permissions. Seems like in such a situation Lambda function may not have sufficient privileges to perform operations on S3. For example - The execution role of Lambda may just have read permissions on S3 and we may be trying to perform PutObject operation.
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Ans. LDAP servers are typically used in J2EE applications to authenticate and authorise users. LDAP servers are hierarchical and are optimized for read access, so likely to be faster than database in providing read access.
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LikeDiscussCorrect / Improve  java   j2ee   ldap   servers   authentication   authorization   architecture   technical lead   technical architect  production support Asked in 1 Companies
Ans. Http is connection less by default. header informs hosts to keep the connection alive so that the same connection can be reused for multiple communication.
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Q20. Explain Application / Server architecture being used in your project ?
or
Explain your project architecture ?
Ans. We are using cluster of Web servers and Application servers. Load Balancer is used to manage the load between them. Down the layer we have middleware server and then DB server to access database.
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Q21. How do you monitor the server resources if inadvertently high traffic is reported ?
Ans. We use SAR command for that purpose. We also have GUI system monitoring tool to keep real time check of requests, load and memory usage.
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LikeDiscussCorrect / Improve  server monitoring   production support   servers   website traffic   system monitoring   sar   application support
Ans. It is the ability to deploy changes on the fly without need to first build , deploy and then restart. All these functions happens on the fly as soon as the changes are made to the code.
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LikeDiscussCorrect / Improve  hot deployment  deployment   container   application server  production support
Ans. Cold Deployment is a conventional deployment mechanism that follows the multi step process to deploy code changes to the running app i.e Build -> Deploy - Restart.
whereas
Hot Deployment is deployment changes on the fly without need to first build , deploy and then restart. All these functions happens on the fly as soon as the changes are made to the code.
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LikeDiscussCorrect / Improve  Hot deployment  cold deployment  application server  production support
Q24. Which Web and Application server is being used by your application ?
Ans. By specifying XSiteScriptingProtection within wc-server.xml. Prohibited characters and attributes are specified within XSiteScriptingProtection to protect the application from any XSS attach.
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Ans. A sandbox is a testing environment that isolates untested code changes and outright experimentation from the production environment or repository.
It's an environment that's usually reserved for integration testing with external clients and modules with mock code so as to enable some sort of integration testing before the actual project is deployed.
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Ans. Load Balancing is a provision to improve performance by reducing load on a single machine / server. Traffic or load is distributed among different machines and hence resulting in better performance / response time by leveraging more resources.
Failover is a provision to achieve better availability by switching to a backup server in case of failure.
Load Balancing aims as improving performance whereas failover aims at improving availability.
We can achieve both together by using a Load Balancing system which will isolate an instance in case of it's failure.
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Q29. What do you understand by "Scaling Trigger" ?
Ans. It's a configuration for auto scaling environment that specify the attributes / conditions for scaling instances up and down. For example - We may like environment to scale up when the number of requests / sec increases a particular threshold and scale down when it decreases below a threshold.
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Ans. Manual scaling is the process of scaling instances up and down in a an enviornment manually by observing the scaling trigger whereas Auto scaling is the process wherein a Trigger condition specified as a scaling trigger will trigger scaling up and down of instances.
for example - If an organization has a policy of scaling up if requests / sec / instance exceeds 10000, Operations team will have to manually monitor the metric and they can request scaling up and down as the need arise. Manual scaling offers flexibility as team can scale on the basis of combination of factors and can take decision on flyby requires continuous monitoring.
The same trigger can be fed as triggering policy to the environment and can be taken care by the system. This requires availability of such triggering policy within the environment configuration but as it's automatically handled, requires no supervision.
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LikeDiscussCorrect / Improve  Scaling  manual scaling   auto scaling   manual vs auto scaling  production support