Content Delivery Network
Definition
A service that provide global caching.Benefits
Reduce latency by routing client to nearest data node.
Distribute load to multiple nodes
Redundancy by replication
Availability
scalability
First access to the file is slower(subsequent access is faster by accessing local region cache)
Cache content (files) on many nodes globally around the world.
Only master copy matters.
It differs from multisite deployment in term of content vs application, reading vs reading and writing.
Using URL provided by CDN provider so that CDS can determine when to use cache
Whenever user want to access content controlled by CDN service, CDN will determine closest CDN node to serve client. anycast protocal)
Cached content has expiration period, and changes will be propagated by CDN service.
scalability
Drawbacks
First access to the file is slower(subsequent access is faster by accessing local region cache)
Mechanics
Edge caching. providing content to user from closest location. CDN's role is to provide edge caching.Cache content (files) on many nodes globally around the world.
Only master copy matters.
It differs from multisite deployment in term of content vs application, reading vs reading and writing.
Using URL provided by CDN provider so that CDS can determine when to use cache
Whenever user want to access content controlled by CDN service, CDN will determine closest CDN node to serve client. anycast protocal)
Cached content has expiration period, and changes will be propagated by CDN service.
Challenges
Cache can be out of dated. Sync needs time to happen. (example of eventual consistency. immediate consistency is traded off to availability ad scalability)Usage
Good for repeatedly used files, big multimedia files such as video and voice content
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