AWS Certified Foundational CLF-C02 Book

The architecture concept of the AWS Cloud that meets the requirements of the company that wants to migrate to the AWS Cloud and needs the ability to acquire and release resources as needed is elasticity. Elasticity means that AWS customers can quickly and easily provision and scale up or down AWS resources as their demand changes, without any upfront costs or long-term commitments. AWS provides various tools and services that enable customers to achieve elasticity, such as Amazon EC2 Auto Scaling, Amazon CloudWatch, and AWS CloudFormation. Elasticity helps customers optimize their performance, availability, and cost efficiency. Availability, reliability, and durability are other architecture concepts of the AWS Cloud, but they are not directly related to the ability to acquire and release resources as needed. Availability means that AWS customers can access their AWS resources and applications whenever and wherever they need them. Reliability means that AWS customers can depend on their AWS resources and applications to function correctly and consistently. Durability means that AWS customers can preserve their data and objects for long periods of time without loss or corruption12

 Spot Instances are spare Amazon EC2 instances that are available at up to 90% discount compared to On-Demand prices. They are suitable for workloads that can tolerate interruptions, such as batch processing, data analysis, and testing. Spot Instances are allocated based on the current supply and demand, and can be reclaimed by AWS with a two-minute notice when the demand exceeds the supply5. Convertible Reserved Instances are a type of Reserved Instances that provide a significant discount (up to 54%) compared to On-Demand prices and a capacity reservation for Amazon EC2 instances. They are available in 1-year or 3-year terms and allow users to change the instance family, size, operating system, or tenancy during the term. Standard Reserved Instances are another type of Reserved Instances that provide a larger discount (up to 75%) compared to On-Demand prices and a capacity reservation for Amazon EC2 instances. They are available in 1-year or 3-year terms and do not allow users to change the instance attributes during the term. Dedicated Hosts are physical servers with Amazon EC2 instance capacity fully dedicated to the user’s use. They are suitable for users who have specific server-bound software licenses or compliance requirements.

According to the AWS shared responsibility model, AWS is responsible for the security of the cloud, while the customer is responsible for the security in the cloud. This means that AWS provides the physical and environmental controls, the service and communications protection, and the awareness and training for its employees, while the customer provides the patch and configuration management, the identity and access management, the data encryption, and the firewall configuration for its resources3.

 The combination of AWS services that the application can use to migrate to a microservices-based application are Amazon Simple Queue Service (Amazon SQS) and AWS Lambda. Amazon SQS is a fully managed message queuing service that enables customers to decouple and scale microservices, distributed systems, and serverless applications. The application can use Amazon SQS to send, store, and receive messages between the microservices, ensuring that each message is processed only once and in the right order. AWS Lambda is a serverless compute service that allows customers to run code without provisioning or managing servers. The application can use AWS Lambda to create and deploy microservices as functions that are triggered by events, such as messages from Amazon SQS. AWS Migration Hub, AWS AppSync, and AWS Application Migration Service are not the best services to use for migrating to a microservices-based application. AWS Migration Hub is a service that provides a single location to track the progress of application migrations across multiple AWS and partner solutions. AWS AppSync is a service that simplifies the development of GraphQL APIs for real-time and offline data synchronization. AWS Application Migration Service is a service that enables customers to migrate their on-premises applications to AWS without making any changes to the applications, servers, or databases.