Today we resume our discussion on the AWS papers in software architecture which suggests five pillars:
- Operational Excellence for running and monitoring business critical systems.
- Security to  protect information, systems, and assets with risk assessments and mitigation strategies.
- Reliability to  recover from infrastructure or service disruptions
- Performance Efficiency to ensure efficiency in the usage of resources
- Cost Optimization  to help eliminate unneeded cost and keeps the system trimmed and lean.
The guidelines to achieve the above pillars include:
1. Infrastructure capacity should be estimated not guessed
2. Systems should be tested on production scale to eliminate surprises
3. Architectural experimentation should be made easier with automation
4. There should be flexibility to evolve architectures
5. Changes to the architecture should be driven by data
6. Plan for peak days and test at these loads to observe areas of improvement
We look at the security pillar today:
The security pillar emphasizes protection of information, systems and assets. There are six design principles for security in the cloud:
It implements a strong identity foundation where the privileges are assigned on a need by need basis. and there is separation of concerns. It centralizes privilege management and reduces usage of long term credentials.
It also monitors, alerts and audits actions to respond and take actions.
It applies security at all layers and not just the one at the edge so that the impact radius is covered in full
It automates mechanisms that are necessary for controls and restrictions
It protects data in transit and at rest with the use of access tokens and encyrption
It prepares for security events when many are affected.

#codingexercise
Check if a number is Fibonacci :
boolean is Fibonacci(uint n)
{
return IsSquare(5*n*n + 4)  || IsSquare(5*n*n - 4);
}
A way to test for squares is to binary chop the squares until we find something closest to either or both of the required values