Module 12

Caching Analogy

Things that should be cached

• Static and frequently accessed data

• Results of computationally intensive calculations

• Results of time-consuming, frequently used, or complex database queries

Content Delivery Network

• Is a globally distributed system of caching servers

• Has intermediary servers between the client and the application

• Caches copies of commonly requested files (static content)

• Delivers a local copy of the requested content from a nearby cache edge or point of presence

Types of data that should be cached by CloudFront

CloudFront

• Is a CDN service that delivers content across the globe securely with low latency and high transfer speeds

• Provides high-speed content distribution by delivering through edge locations

• Improves application resiliency from distributed denial of service (DDoS) attacks by leveraging services such as AWS Shield and AWS WAF

Edge Locations	Regional Edge caches
A lot and closer to users	Fewer and farther away frm users
Smaller caches	Bigger caches
Helps server popular content	Help with les popular content

CloudFront Operations

CloudFront Distributions

Used for when you ant CloudFront to distribute your content

Elasticache

• Is a fully managed, key-value, in-memory data store with sub-millisecond latency

• Sits between an application and an origin data store

• Decreases access latency and eases the load of databases and applications

• Provides a high performance and cost-effective in-memory cache

• Is fully compatible with open source Redis and Memcached engines

Two Types

ElastiCache for Memcached

Elasticache for Redis

A time to live must be set for the cached data

Handling Stale Data

Lazy Loading	Write-Through
This strategy updates the cache after the data is requested	This strategy updates the cache immediately after updating the primary database
The cache contains only data that the application actually requests	The cache is up-to-date with the primary database (most likely data will be found in the cache)
This strategy requires a programmatic strategy to handle keeping the cache as up to date	This strategy results in an increase in cost from storing data in-memory that you might not use

Lazy Loading Operations

The information won't update the cache until it gets a READ request from a user

Write-Through Operations

Real-time updating of the cache