scale your application while improving performance and lowering costs (svc203) | aws re:invent 2013
Post on 27-Jan-2015
112 Views
Preview:
DESCRIPTION
TRANSCRIPT
© 2013 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified, or distributed in whole or in part without the express consent of Amazon.com, Inc.
Cache is King: Scale Your Application while Improving
Performance and Lowering Costs
November 15, 2013
Cash is King Cash is King
Cache is Cash
Httparchive
Content Breakdown
87% of Your Site Consists Of Static/Re-usable Content
56% of The Internet’s Content is NOT Cached Today
But Wait…
Cache is King
Source: httparchive.org
300K Tracked Websites Oct 15 2012-Oct 1 2013
~56% {
CACHE EVERYTHING
Browser Cache
Edge Cache
Web Cache
Application Cache
Database Cache
Image Source: cakeormistake.wordpress.com
Speed of Light ~300,000 Km/s
Image Source: wordlesstech.com
~200,000 Km/s through fiber
Image Source: www2.wiringandcabling.com
Download Performance
Round Trip: 13,026 km
Download Performance
Round Trip: 13,026 km
Theoretical: 65 ms
Download Performance
Round Trip: 13,026 km
Theoretical: 65 ms
Measured: 68 ms
Time to First Byte
68 ms
Client Server
Time to First Byte
68 ms
68 ms
Client Server
SYN
SYN/ACK
Time to First Byte
68 ms
68 ms
68 ms
Client Server 136 ms
SYN
SYN/ACK
ACK,
GET /image.jpg HTTP/1.1
Browser Cache
Browser Caching
Set max-age or expiry date in the headers.
HTML5 Application Cache.
Helps eliminate network latency.
But… Browser cache size is limited. (e.g. IE is 8-50M, Chrome is < 80M, Firefox is 50MB, etc.)
Browser Cache
Edge Cache
Time to First Byte
68 ms
68 ms
68 ms
Client Server 136 ms
SYN
SYN/ACK
ACK,
GET /image.jpg HTTP/1.1
Bring the Bytes Closer to Your Users
68 ms
Client Origin
SYN
10 ms
SYN/ACK
GET /image.jpg HTTP/1.1 ACK,
GET /image.jpg HTTP/1.1
CloudFront
Saves 68 ms
RTT
SYN
SYN/ACK
Time to first byte: 20 ms vs. 136 ms
Amazon CloudFront: 46 Global Locations
=
Edge Cache: Amazon CloudFront
Amazon S3
Elastic Load
Balancing
Mobile Clients
Browsers/Desktop
Clients
Tablets/Devices
Amazon CloudFront
Edge Location
Edge Cache
How do you decide what to cache?
• Static or Re-Usable Content
• Customized Content
• On-Demand and Live Video
• Dynamic or Unique Content
Cache Static or Re-Usable Content
HTTP/1.0 200 OK
Date: Mon, 19 Mar 201 12:51:28 GMT
Server: Apache
Last-Modified: Mon, 19 Mar 2012 07:15:25 GMT
Accept-Ranges: bytes
Content-Length: 1918
Cache-Control: max-age=86400
Content-Type: image/jpeg Vary: Accept-Encoding
Age: 16
X-Cache: Hit from cloudfront
Connection: keep-alive
Cache Customized Content
Customized Content
Cache Video Content
Caching Your Live Stream?
Source
HTTP
Cache
Edge
Paris
New York
Encoder
HLS, HDS,
Smooth Streaming
Hong Kong
Dynamic Content?
Zero TTL – cannot be cached! CloudFront can still help…
Dynamic Content?
Zero TTL – cannot be cached! CloudFront can still help…
TCP/IP optimizations for the network path
Keep-Alive Connections to reduce RTT
SSL Termination close to viewers
POST/PUT upload optimizations
Latency Based Routing
Low prices, same as static content delivery!
“We are excited to use CloudFront's new
POST, PUT, PATCH, and DELETE capabilities
to accelerate our RESTful APIs on Amazon
EC2. With these new HTTP methods we can
now take advantage of CloudFront’s global
footprint and optimized connections back to
our origin servers in AWS. Routing our
customers’ API requests via a CloudFront edge
location near them will help improve their
experience by minimizing packet loss and
upload latency. This will help provide a
streamlined experience for our customers.”
- Ilan Rabinovitch, Tech Lead, Site Reliability Engineering
Browser Cache
Edge Cache
Web Cache
You can’t have dessert,
until you have your dinner!
-An Experiment. https://secure.flickr.com/photos/stephen-oung/6319155216/
Experiment Premise
• Start with basic infrastructure. – Single m1.large EC2 instance running Amazon Linux
– Single non-Multi-AZ m1.xlarge RDS MySQL 5.6 instance
– Apache httpd-2.2.25
– PHP 5.3.27
– Drupal Commerce Kickstart 7.2
– EIP on Instance
• Throw a ton of traffic at it. – 8,000,000 queries, 40 per second, from 4 other instances.
• Profile it. – New Relic PHP agent
– webpagetest.org
Experiment Infrastructure
Web/App
Instance
Elastic IP Amazon RDS
DB Instance Clients
Results? (not pretty)
14.7 second responses
Mostly Static Data
Low RPM
Web Cache
Webserver or proxy caches would live between
your CDN/Users and your web tier and can offer
up increased cost performance via reducing
internal application and database load. Can also
offer up increased edge to origin speed for lots of
content.
Web Cache
Popular solutions: – Varnish
– Nginx
– Apache with mod_cache/mod_proxy
– Squid
– Perlbal
– Language/framework caches (i.e., APC, Zend)
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing
Internet
Gateway
Amazon
Route 53
Amazon
CloudFront
Customer
Traffic
Web Cache
• Opt for in-memory caching when possible.
• Pay attention to your cache hit/miss ratios. It could be a sign that you need to re-size the instances or re-size the number of nodes in your cache pool.
• Set smart TTLs so that you don’t affect new deploys or cache content for too long.
• Be smart about what cookies can burst cache and what cookies can’t. Don’t serve up other people’s content or stale dynamic pages.
Web Cache
How do you decide what to cache? – All logged out user pages
– Any completely static pages
– Traffic/log analysis
• Look at your web logs/CDN logs
• Find heavily hit pages
• Figure out how often they actually change
• Apply a TTL to that page to be cached
– Even 60 second TTLs could help drastically!
Browser Cache
Edge Cache
Web Cache
Application Cache
Application Cache
Application level caches for information such
as session data, temporary application data
such as cart information, and live aggregation
of data feeds.
Application Cache
Popular solutions: – Memcached
– Redis
– Cassandra
– Amazon DynamoDB
Application Cache
Availability Zone
VPC Subnet VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing ElastiCache
Cache Node
Availability Zone
VPC Subnet VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing ElastiCache
Cache Node
Internet
Gateway
Application Cache
Availability Zone
VPC Subnet VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing ElastiCache
Cache Node
Availability Zone
VPC Subnet VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing ElastiCache
Cache Node
Internet
Gateway
Amazon DynamoDB Session Handler for PHP
https://aws.amazon.com/sdkforphp/
Application Cache
Internet
Gateway
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing Squid Proxy
Instances Amazon
DynamoDB
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing Squid Proxy
Instances
Application Cache
Internet
Gateway
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing Squid Proxy
Instances Amazon
DynamoDB
Availability Zone
VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing Squid Proxy
Instances
Application Cache
Use Cases: – Session information
– Temporary data
• Cart info, metadata
– Rate limiting
• Fight abuse of APIs, spamming, functionality abuse
– Counters
• Views, Scores, Leader Boards
Application Cache
How do you decide what to cache?
– Ideally, you have to treat data you cache at this tier as
loss tolerant if working with in-memory caches.
– Session information that wouldn’t make sense in
cookies or in a true DB.
– Look at the kind of data your application is generating
and storing in a DB that it might not need to.
Browser Cache
Edge Cache
Web Cache
Application Cache
Database Cache
Database Cache
Reduce workload on database servers by
caching commonly requested information, or
any information that might not change
frequently (i.e., user info, listing info, product
info).
Database Cache
Popular solutions: – In-engine query caches
– Memcached
• On dedicated host
• On DB host (built in w/ MySQL 5.6)
– Redis
• On dedicated host
Database Cache
A word of caution: In-engine DB caches are often not recommended for
many use cases, as they can significantly impact the
performance of many databases. Depending on the
workload and dataset you have, an in-engine query
cache might not be a good idea for you. We recommend
off DB caches where possible.
Database Cache
Availability Zone
VPC Subnet VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing ElastiCache
Cache Node
Availability Zone
VPC Subnet VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing ElastiCache
Cache Node
Internet
Gateway
RDS Instance
Primary (M-AZ)
RDS Instance
Standby (MAZ)
Database Cache
Availability Zone
VPC Subnet VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing ElastiCache
Cache Node
Availability Zone
VPC Subnet VPC Subnet VPC Subnet
Elastic Load
Balancing Cache
Instances
Web/App
Instances
Elastic Load
Balancing ElastiCache
Cache Node
Internet
Gateway
RDS Instance
Primary (M-AZ)
RDS Instance
Standby (MAZ)
Memcached – Code Sample function retrieveValue($query)
{
$queryId = md5($query);
if ($myValue = $memcache->get($queryId))
{
return $myValue;
}
else
{
$myValue = dbfetch($query);
$memcache->set($queryId, $myValue);
return $myValue;
}
}
MySQL 5.6 + Memcached
RDS MySQL supports version
5.6 with integrated Memcached
on the instance: – Part of the InnoDB engine
– Memcached running as part of MySQL
talks directly to data in InnoDB tables,
essentially turning MySQL into a fast
“key-value store”
– From the opposite view point, adds
persistence to Memcached
– Same Memcached API as standalone
https://dev.mysql.com/doc/refman/5.6/en/innodb-memcached-intro.html
AWS Marketplace & Partners Can Help
• Customers can find, research, buy
software.
• Simple pricing, aligns with Amazon
EC2 usage model.
• Launch in minutes!
• Marketplace billing integrated into your
AWS account.
• 1100+ products across 24+ categories.
Learn more at: aws.amazon.com/marketplace
Back To Our
Experiment!
https://secure.flickr.com/photos/toyochin/1382531438/
Experiment Infrastructure (original)
Web/App
Instance
Elastic IP Amazon RDS
DB Instance Clients
Results? (not pretty)
14.7 second responses
Mostly Static Data
Low RPM
Experiment Infrastructure (with cake)
• Added in ElastiCache Memcached cache.m1.large
• Added in Amazon CloudFront for static content – Tuned expires and cache headers in Apache
• Added in APC for PHP caching – Increased memory to 128Mb, no other changes
• Did nothing to the DB
• Drupal memcached & CDN modules
CloudFront
Experiment Infrastructure (with cake)
Web/App
Instance
Elastic IP
Amazon RDS
DB Instance
Clients
ElastiCache
Cache Node
Results? (AWESOME!)
response time ~1/2
~2x RPM
Repeat Page view from 15.8sec to 2.75sec
Easy as Pie!
https://secure.flickr.com/photos/linecon0/2654865842/
Toronto Star
• Canada’s largest daily newspaper
• Focused on metro Toronto
• 3.3 million monthly unique visitors
• Small in-house digital group,
supported by vendors & corporate IT
• Digital group run as “startup” within
corporate structure
• Tech stack includes Java, PHP,
Ruby, Python
mystar
Wheels.ca
Toronto.com
Thegridto.com
Why Cache?
• Performance
• Scalability
• Reliability
• Cost
Breaking News
Breaking News: Client View
Breaking News: Server View
The Caching Onion
DB
App
Reverse proxy
Edge
Edge – The Onion Skin
• Examples: Akamai,
CloudFront
• Static Asset caching
• Full site caching
• Origins
• Behaviors
• thestar.com, wheels.ca,
toronto.com, thegridto.com
Edge
Edge – The Onion Skin
Production - US East Region
Elastic Load Balancer
Dispatcher/ApacheAmazon Linux 64 Bit
C1 Medium
Dispatcher/ApacheAmazon Linux 64 Bit
C1 Medium
Publish CQ/CRXAmazon Linux 64 Bit
C1-Xlarge
Master
Author CQ/CRXAmazon Linux 64 Bit
C1-Xlarge
Dispatcher/ApacheAmazon Linux 64 Bit
C1 Medium
Availability Zone A Availability Zone DAvailability Zone B
Cloudfront
VPC
Standby
Author CQ/CRXAmazon Linux 64 Bit
C1-Xlarge
Publish CQ/CRXAmazon Linux 64 Bit
C1-Xlarge
Publish CQ/CRXAmazon Linux 64 Bit
C1-Xlarge
Publish CQ/CRXAmazon Linux 64 Bit
C1-Xlarge
Publish CQ/CRXAmazon Linux 64 Bit
C1-Xlarge
Publish CQ/CRXAmazon Linux 64 Bit
C1-Xlarge
Thestar.com
architecture
Production - US East Region
Elastic Load Balancer
Dispatcher/ApacheAmazon Linux 64 Bit
C1 Medium
Dispatcher/ApacheAmazon Linux 64 Bit
C1 Medium
Publish CQ/CRXAmazon Linux 64 Bit
C1-Xlarge
Master
Author CQ/CRXAmazon Linux 64 Bit
C1-Xlarge
Dispatcher/ApacheAmazon Linux 64 Bit
C1 Medium
Availability Zone A Availability Zone DAvailability Zone B
Cloudfront
VPC
Standby
Author CQ/CRXAmazon Linux 64 Bit
C1-Xlarge
Publish CQ/CRXAmazon Linux 64 Bit
C1-Xlarge
Publish CQ/CRXAmazon Linux 64 Bit
C1-Xlarge
Publish CQ/CRXAmazon Linux 64 Bit
C1-Xlarge
Publish CQ/CRXAmazon Linux 64 Bit
C1-Xlarge
Publish CQ/CRXAmazon Linux 64 Bit
C1-Xlarge
Whole Site Delivery
• Cache everything possible
• No server side cookies written,
only select pages pass query
strings
• Control caching granularly using
19 different rules
• We use a single origin, but Elastic
Load Balancing and multi-tiered
multi-AZ configuration on backend
• Planning a multi-region DR
architecture that will also leverage
Amazon CloudFront
Reverse Proxy / Web Accelerator
• Examples: Varnish, Nginx, Apache
• Serves “static” content
• Reduce load on app server
• wheels.ca, mystar, thestar.com, thegridto.com
Reverse proxy
Reverse Proxy / Web Accelerator
mystar
Reverse Proxy / Web Accelerator
mystar
Reverse Proxy / Web Accelerator
Wheels.ca
App-level caching
• Examples:
Memcached, Reddis – ElastiCache now supports
both
• Session caching
• View caching
• mystar
App
App-level caching
Database caching
• Example:
Memcached
• Cache frequent SQL
queries
• Reduce DB server
load, response time
• mystar, wheels.ca
DB
Database Caching
Wheels.ca
Database Caching
Wheels.ca
Please give us your feedback on this
presentation
As a thank you, we will select prize
winners daily for completed surveys!
SVC203
APPENDIX
Reverse Proxy / Web Accelerator
Varnish Cache is a web application accelerator also
known as a caching HTTP reverse proxy. You install it
in front of any server that speaks HTTP and configure
it to cache the contents. Varnish Cache is really, really
fast. It typically speeds up delivery with a factor of 300
- 1000x, depending on your architecture.
- varnish-cache.org
Reverse Proxy / Web Accelerator
Nginx (pronounced "engine x") is an open
source reverse proxy server for HTTP,
HTTPS, SMTP, POP3, and IMAP protocols,
as well as a load balancer, HTTP cache, and
a web server (origin server). The nginx
project started with a strong focus on high
concurrency, high performance and low
memory usage.
- Wikipedia
App-level caching Memcached
Free & open source, high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load.
Memcached is an in-memory key-value store for small chunks of arbitrary data (strings, objects) from results of database calls, API calls, or page rendering
App-level caching
Redis
Redis is an open source, BSD licensed, advanced
key-value store. It is often referred to as a data
structure server since keys can contain strings,
hashes, lists, sets and sorted sets. – Redis.io
Edge – The Onion Skin
“A content delivery network is a large distributed
system of servers deployed in multiple data
centers across the Internet. The goal of a CDN is
to serve content to end-users with high availability
and high performance.” - Wikipedia
Reverse Proxy / Web Accelerator
“A web accelerator is a proxy server that
reduces web site access times. They can be
a self-contained hardware appliance or
installable software.” - Wikipedia
top related