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Ans. High bandwidth and availability in NAT Gateway
NAT Gateway is completely managed by AWS
NAT Gateway is auto scalable
NAT Instance is just like EC2 instance and hence backed by security group
NAT Instance can be used as bastion host whereas NAT Gateway cannot be.
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Ans. With the advent of Internet, HTTP is the most preferred way of communication. Most of the clients ( web thin client , web thick clients , mobile apps ) are designed to communicate using http only. Web Services using http makes them accessible from vast variety of client applications.
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Ans. Web Service promotes looser coupling but with comes with coding and performance overheads. Jars provide better performance and may be lesser coding but are problematic with update distribution. If the situation doesn't require frequent dependency updates and if it's only read operation of persistence, Having dependencies should be a better choice , otherwise web service.
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Ans. Request Body in case of Get Request has no meaning and hence it's not parsed when the request is received. Alternatively Request Parameters are passed as either Path Params or Query Params.
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Ans. A Web service is a service offered by one system to another, for communication over web through http. XML are JSON are usually used for sending across information from one system to another.
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Ans. There is no direct way to make stateful REST service but when first time request send to server, generate the token on server and send back to client. When every time new request is send the token is send to identify the request is coming from same client.
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Ans. RMI uses a standard mechanism for communicating with remote objects i.e stubs and skeletons. A stub for a remote object acts as a client's local representative. The caller invokes a method on the local stub which is responsible for carrying out the method call on the remote object.
Stub resides at the client that upon calling whose method results in establishing connection with the server, serializing and mar shelling the request and then waiting for the response whereas skelton resides at the server that receives the request, unmarshal it and then deserialize to fulfil the request.
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Ans. If the number of input values is large, we can go about passing them as query params instead of path params. If the number is even larger and complex , its better to create a post service that behaves like a get service. Though this practice is not recommended but technically it can be accomplished.I dont mind doing it if the exceptionally large number of input would make it much more confusing.
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Ans. These are the platforms or set of services provided by Amazon for cloud services , database storage , content delivery and other business applications and solutions.
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Ans. Amazon Elastic Compute Cloud or EC2 provides scalable computing capacity in the AWS cloud. It can be used to create Virtual Environments , storage and configure. EC2 enables to upgrade or downgrade infrastructure according to the rules defined ( with fluctuation in latency, traffic etc )
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Ans. Latency is the delay incurred while communicating a message i.e the time took the message in transit over network.
processing time is the delay it took for the server to process the request.
Response time is the sum total of latency and processing time.
For example -
Let's say it takes 1 ms for the request to reach from client to server and similar 1 ms for the response to come back to client. Moreover it takes approx 10 ms for the application to process the request. So The response time would be outward latency + processing time + inward latency = 12 ms
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Ans. Amazon CloudWatch is a monitoring service for AWS cloud resources like Beanstalk and DB instances. We can use CloudWatch to monitor the state of resources, collect metrices, set alarms and appropriate response to the alarm state.
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Ans. A shard is a uniquely identified group of data records in a stream or we can say that Shard is a partition in Kinesis stream. A shard supports a fixed bandwidth i.e fixed number of messages per second. The total capacity of the stream is the sum of the capacities of its shards. If the data rate changes, we can allocate / deallocate more shards to accommodate that.
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