Design Strategies for Loosely Coupled Systems

Answer - B and D.

The below diagram shows the ideal design which uses SQS and separate environments for web and worker processes.

The SQS queue manages the communication between the web and worker roles.

One example is the way Elastic beanstalk manages worker environments.

For more information on this, please visit the below URL:

The ideal design strategy when designing loosely coupled systems is to have the web and worker roles running on separate EC2 instances, and to use SQS to establish communication between them.

Loosely coupled systems are designed to have minimal dependencies between components, allowing for increased flexibility, scalability, and maintainability. In order to achieve this, it is recommended to keep components separated from each other and to use messaging services to establish communication.

Option A, having the web and worker roles running on the same set of EC2 instances, goes against the principle of loose coupling as it introduces dependencies between the roles. If the web role experiences a spike in traffic, it could potentially affect the performance of the worker role, leading to decreased efficiency and reliability.

Option C, using SNS to establish communication between the web and worker roles, is a valid option, but it does not address the issue of separation of roles. SNS is a publish-subscribe messaging service that allows multiple recipients to receive messages from a single publisher. While it can be used to communicate between components, it does not guarantee separation of roles.

Option D, using SQS to establish communication between the web and worker roles, is the recommended approach for designing loosely coupled systems. SQS is a fully managed message queuing service that allows for decoupling of components, and ensures reliable and scalable communication between them. By using separate EC2 instances and SQS, the web and worker roles can operate independently of each other, ensuring optimal performance and scalability.

In summary, the best design strategy for designing loosely coupled systems involves using separate EC2 instances and SQS to establish communication between components, while avoiding dependencies between them.