Amazon CloudFront is a content delivery network (CDN) that speeds up distribution of files like web site content, APIs, video streams and more. It works by caching content at edge locations close to users to avoid fetching files from origin servers each time. Users receive responses from the closest edge server, improving performance. CloudFront also integrates with other AWS services and charges based on data transfer, requests and invalidations.

1. Amazon CloudFront
An introductory discussion

2. What is Amazon CloudFront?
• Amazon CloudFront is a web service for content
delivery.
• It integrates with other Amazon Web Services to
give developers and businesses an easy way to
distribute content to end users with low latency,
high data transfer speeds, and no commitments.
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3. How does Amazon CloudFront provide higher performance?
• Amazon CloudFront employs a network of edge locations that cache copies of
popular files close to your viewers.
• Amazon CloudFront ensures that end-user requests are served by the closest edge
location. As a result, requests travel shorter distances to request objects,
improving performance.
• For files not cached at the edge locations, Amazon CloudFront keeps persistent
connections with your origin servers so that those files can be fetched from the
origin servers as quickly as possible.
• Finally, Amazon CloudFront uses additional optimizations – e.g. wider TCP initial
congestion window – to provide higher performance while delivering your content
to viewers.
• Amazon CloudFront also uses techniques such as collapsing simultaneous viewer
requests at an edge location for the same file into a single request to your origin
server. This reduces the load on your origin servers reducing the need to scale your
origin infrastructure, which can bring you further cost savings.
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4. What is the price of Amazon CloudFront?
• Amazon CloudFront charges are based on actual usage of the service in three
areas:
• Data Transfer
– You will be charged for the volume of data transferred out of the Amazon CloudFront
edge locations, measured in GB. You can see Amazon CloudFront data transfer
pricing here.
• HTTP/HTTPS Requests
– You will be charged for number of HTTP/HTTPS requests made to Amazon CloudFront
for your content. You can see the rates for HTTP/HTTPS requests here.
• and Invalidation Requests
– You may invalidate up to 1,000 files each month from Amazon CloudFront at no
additional charge. Beyond the first 1,000 files, you will be charged per file for each file
listed in your invalidation requests. You can see the rates for invalidation requests here.
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5. Where are the edge locations
United States Europe Asia South America
Ashburn, VA (2) Amsterdam Hong Kong Sao Paulo
Dallas/Fort Worth, TX (2) Dublin Osaka
Jacksonville, FL Frankfurt (2) Singapore (2)
Los Angeles, CA (2) London (2) Sydney
Miami, FL Milan Tokyo
New York, NY (2) Paris (2)
Newark, NJ Stockholm
Palo Alto, CA
San Jose, CA
Seattle, WA
South Bend, IN
St. Louis, MO
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6. How does Amazon CloudFront speed up my entire website?
• Amazon CloudFront uses standard cache control headers you set on your files to
identify static and dynamic content.
• When using AWS origins, you benefit from improved performance, reliability, and
ease of use as a result of AWS’s ability to track and adjust origin routes, monitor
system health, respond quickly when any issues occur, and the integration of
Amazon CloudFront with other AWS services.
• You also benefit from using different origins for different types of content on a
single site – e.g. Amazon S3 for static objects, Amazon EC2 for dynamic content,
and custom origins for third-party content – paying only for what you use.
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7. How long will Amazon CloudFront keep my files at the edge locations?
• By default, if no cache control header is set, each edge location checks for an
updated version of your file whenever it receives a request more than 24 hours
after the previous time it checked the origin for changes to that file. This is called
the “expiration period.”
• You can set this expiration period as short as 0 seconds, or as long as you’d like, by
setting the cache control headers on your files in your origin.
• Amazon CloudFront uses these cache control headers to determine how
frequently it needs to check the origin for an updated version of that file.
• For expiration period set to 0 seconds, Amazon CloudFront will revalidate every
request with the origin server.
• If your files don’t change very often, it is best practice to set a long expiration
period and implement a versioning system to manage updates to your files.
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8. What are Distributions?
• After you store your objects in your origin server, you create a distribution, which
tells CloudFront where your objects are.
• Suppose your origin is an Amazon S3 bucket called myawsbucket that contains an
image called images/image.jpg. You want to display the image on your web page.
If you display the image directly from your Amazon S3 bucket, the link is:
– http://myawsbucket.s3.amazonaws.com/images/image.jpg
• If you instead display the image using CloudFront the link is:
– http://myawsbucket.cloudfront.net/images/image.jpg
• If you already have a domain name (for example, example.com) that you want to
use for links to your objects, you can specify up to 10 alternate domain names,
also known as CNAMEs. If you add a alternate domain name for example.com, the
link is:
– http://example.com/images/image.jpg
• You can create two types of distributions:
– A download distribution.
– A streaming distribution delivers
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9. How CloudFront Delivers Content
1 You configure your origin servers, which are the servers from which CloudFront gets your files for distribution at edge
locations all over the world. For this example:
You create an Amazon S3 bucket for your image files, and you make the files publicly available.
You configure an HTTP server for your HTML content.
2 You upload your files to your origin servers.
3 You create a CloudFront distribution, which tells CloudFront which origin servers to get your files from when end users
request the files through your web site or application. For this example, you configure your distribution so CloudFront
gets your image files from one server and PHP files from another.
A distribution also specifies details like whether you want CloudFront to log all requests and whether you want the
distribution to be enabled as soon as it's created.
4 CloudFront returns the domain name that you use for your objects as you develop your web site or application. For
example, if CloudFront returns d1234.cloudfront.net as the domain name for your distribution, the URL for image.jpg in
your Amazon S3 bucket (or in the root directory on an HTTP server) will be http://d1234.cloudfront.net/image.jpg.
You can also configure your CloudFront distribution so you can use your own domain name. In that case, the URL
might be http://www.example.com/image.jpg.
5 CloudFront distributes information about your distribution to all of its edge locations.
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10. How CloudFront Delivers Content – contd…
6 You develop your website or application to use the domain name that CloudFront returned in Step 4 or to use your
own domain name, depending on how you configured your distribution.
You can optionally configure your origin server to add headers to the files; the headers indicate how long you want the
files to stay in the cache in CloudFront edge locations. By default, each object stays in an edge location for 24 hours.
7 An end user accesses your website or application and requests an image file and an HTML file.
8 CloudFront determines which edge location can best serve the end user's request. In this example, let's say it's Tokyo.
9 In the Tokyo edge location, CloudFront checks its cache for the requested files. If the files are in the cache, CloudFront
returns them to the end user.
If the files are not in the cache:CloudFront compares the request with the specifications in your distribution and
forwards the request for the files to the applicable origin server for the corresponding file type: to your Amazon S3
bucket for image files and to your HTTP server for the HTML files.
The origin servers send the files back to the CloudFront edge location in Tokyo.
CloudFront forwards the files to the end user and adds the files to the cache in Tokyo for the next time someone
requests those files.
10 After an object has been in an edge cache for 24 hours or for the duration specified in your file headers (see Step 6),
CloudFront forwards the next request for the object to your origin to determine whether the edge location has the
latest version. If the version in the edge location is the latest, CloudFront delivers it to your end user. If not, your origin
sends the latest version to CloudFront, and CloudFront delivers the object to your end user and stores the latest
version in the cache at that edge location.
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11. Everything you need to know about CloudFront is available online…
• http://aws.amazon.com/cloudfront/
• http://aws.amazon.com/cloudfront/pricing/
• http://docs.amazonwebservices.com/AmazonCloudFront/latest/DeveloperGuide/I
ntroduction.html
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