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Getting to 2nd Base with your ContentDelivery Network
Mike BrittainEngineering Architect
Overview
1. Measure your performance2. Tweak your cache TTLs3. Cache dynamic objects4. Cache whole pages5. Inspect origin hits6. Use proper HTTP headers7. Use multiple CDNs8. Review CDN documentation9. Engage your vendor
Overview
20 Minutes
Overview
1. Cache dynamic objects2. Inspect origin traffic3. Cache HTML pages
Typical Setup
Typical Setup
CDN Storage
$$$
Origin Pull
CDN lingo for “reverse proxy”
Response Headers
Cache-control: max-age=3600
Last-Modified: Mon, 16 Mar …
ETag: “82c7-378-8e2a”
http://www.askapache.com/htaccess/apache-speed-etags.html
Revalidation Requests
GET /images/generated.css HTTP/1.1
Host: origin.example.com
If-Modified-Since: Mon, 16 Mar …
If-None-Match: ”82c7-378-8e2a”
HTTP/1.1 200 OK
Content-Length: 35043
... or ...
HTTP/1.1 304 Not Modified
$$$
$
Review Origin Logs
Requests URL Size
28 /images/logo.gif 2 KB
17 /images/nav_tabs.png 5 KB
4,613 /images/annual_report.ppt 16 MB
31 /images/flames.gif 13 KB
Avoid Double Paying
16 MB x 4,600 @ 0.35/GB ≈ $25 (CDN)
16 MB x 4,600 @ 0.50/GB ≈ $36 (origin)
$61
Avoid Double Paying
16 MB x 4,600 @ 0.35/GB ≈ $25 (CDN)
16 MB x 23 @ 0.50/GB ≈ $0.18 (origin)
$25- ish
Cache HTML Pages
Cache HTML Pages
Cache HTML Pages
Page built just
for Mike
Cache HTML Pages
Serve generic version to
the CDN
Use client-side logic for
personalization
Cache HTML Pages
Replace generic
sections with tailored
versions
Cookies,
JavaScript
Cache HTML PagesTrack short history of
user interactions
Fresh data only
where needed
Ajax, Cookies,
JavaScript
Cache HTML PagesUse tracking pixels for
page views
Real time data with Ajax,
or fake it
Ajax, Cookies,
JavaScript
Cache HTML Pages
Search Results,
HTML frag., Public APIs,
XML, JSON, RSS
Do you GET it?
Cache HTML Pages
Cache HTML Pages
TTLs of 3 mins to 1 hr
Psst… under 60 seconds is okay, too.
Cache HTML Pages
92%
Wait… You’re still here?
No, seriously… go away!
HTTP Headers
cURL, telnet, Charles, Fiddler, Firebug, etc.
CDNs Fail
Plan B Split traffic between (similar)
CDNs Origin servers Cloud storage
CDNs Fail
CDNs Fail
Amazon CloudFront: $0.17/GB*
Rackspace Cloud Files: $0.22/GB
JetS3t, Cyberduck, Transit, S3 Browser, S3Fox Plug-in, s3sync.rb, APIs, etc.
Multiple CDNs
Cost vs. Performance
Time
Views
