This document discusses strategies for improving mobile application performance through caching and reducing API requests. It recommends caching responses from APIs and content delivery networks to reduce load on servers. Developer should add Cache-Control headers to responses to ensure caching by clients. The document also provides tips for organizing files in Amazon S3 buckets to optimize storage and retrieval performance.

1. MOBILE API AND
CACHING
Making the most of your APIs

2. PERFORMANCE
MATTERS.

3. MOBILE APPLICATION
AVERAGE API RESPONSE TIME.
1.24seconds
source: New Relic

4. TIME SPENT.
SERVER
20%
NETWORK
80%

5. BASIC MATHEMATICS.
session duration
request duration = requests
per session

6. WILDLY INACCURATE TESTS.
Check my balance
43 requests in 70 seconds
Check-in
46 requests in 30 seconds
Open a message
24 requests in 40 seconds

7. AVERAGE:
0.92second

8. THE HARD STUFF.
•INCREASE SESSION TIME.
•REDUCE REQUEST TIME.

9. DOING MORE.
session duration
request duration = requests
per session

10. MAKE FEWER
REQUESTS
PER ACTION.

11. BE SPECIFIC.

12. WEB BROWSER
CACHES EVERYTHING
UNLESS TOLD
OTHERWISE.

13. MOBILE APPLICATION
CACHES NOTHING
UNLESS TOLD
OTHERWISE.

14. BASIC REQUIREMENT.
ONE =object
ONE
URI

15. FOLLOWING JSON API
GUIDELINES HELPS ENSURE
OBJECT TO URI EQUIVALENCY.
http://jsonapi.org

16. HTTP, FOR YOU
IT WORKS.

17. GET /collections/12 HTTP/1.1
Host: flipbit.dev
!
HTTP/1.1 200 OK
Date: Thu, 17 Oct 2013 01:42:00 GMT
Accept-Ranges: bytes
Content-Type: application/vnd.api+json
Content-Length: 42
Connection: keep-alive
Location: http://flipbit.dev/collections/12

18. GET /collections/12 HTTP/1.1
Host: flipbit.dev
!
HTTP/1.1 200 OK
Date: Thu, 17 Oct 2013 01:42:00 GMT
Last-Modified: Thu, 17 Oct 2013 01:38:57 GMT
ETag: "b79f914dde3ab5e3095372de46591b46"
Expires: Thu, 24 Oct 2013 01:38:57 GMT
Cache-Control: max-age=604800, private
Accept-Ranges: bytes
Content-Type: application/vnd.api+json
Content-Length: 42
Connection: keep-alive
Location: http://flipbit.dev/collections/12

19. GET /collections/12 HTTP/1.1
Host: flipbit.dev
If-Modified-Since: Thu, 10 Oct 2013 20:14:48 GMT
If-None-Match: "a1846ac92492d2347c6235b4d2611184"
!
HTTP/1.1 200 OK
Date: Thu, 17 Oct 2013 01:42:00 GMT
Last-Modified: Thu, 17 Oct 2013 01:38:57 GMT
ETag: "b79f914dde3ab5e3095372de46591b46"
Expires: Thu, 24 Oct 2013 01:38:57 GMT
Cache-Control: max-age=604800, private
Accept-Ranges: bytes
Content-Type: application/vnd.api+json
Content-Length: 42
Connection: keep-alive
Location: http://flipbit.dev/collections/12

20. CACHE-CONTROL
ON AMAZON S3.

21. GET /buket.mycompany.com/welcome.json HTTP/1.1
Host: s3.amazonaws.com
!
HTTP/1.1 200 OK
x-amz-id-2: UleVE3wbOPZa2EW+RpWj834yy5OOMLNmi/w…
x-amz-request-id: 4ADBB2EBF80F5D46
Date: Thu, 17 Oct 2013 01:42:00 GMT
Last-Modified: Thu, 17 Oct 2013 01:38:57 GMT
ETag: "b79f914dde3ab5e3095372de46591b46"
Accept-Ranges: bytes
Content-Type: application/octet-stream
Content-Length: 23
Connection: keep-alive
Server: AmazonS3

22. GET /buket.mycompany.com/welcome.json HTTP/1.1
Host: s3.amazonaws.com
!
HTTP/1.1 200 OK
x-amz-id-2: UleVE3wbOPZa2EW+RpWj834yy5OOMLNmi/w…
x-amz-request-id: 4ADBB2EBF80F5D46
Date: Thu, 17 Oct 2013 01:42:00 GMT
Last-Modified: Thu, 17 Oct 2013 01:38:57 GMT
ETag: “b79f914dde3ab5e3095372de46591b46"
Cache-Control: ???
Expires: ???
Accept-Ranges: bytes
Content-Type: application/octet-stream
Content-Length: 23
Connection: keep-alive
Server: AmazonS3

23. CACHING IS UNCERTAIN.
•There’s no cache-control header so it’s left to the
client to decide.
•iOS most likely will cache between 6 hours and 1 day
and will always revalidate.
•Android it depends, but most likely won’t cache.

24. DON’T LET THE CLIENT DECIDE.
•Add the x-amz-meta-Cache-Control header when
doing a PUT to S3.
•It’s recommended to use a max-age of at least one
month.
•Don’t use x-amz-meta-Expires.
The object will not be cached after its expiry date.

25. CACHE-CONTROL
WITH RUBY ON RAILS.

26. GET /collections/12 HTTP/1.1
Host: app.mycompany.com
!
Cache-Control: max-age=0, private, must-revalidate
Content-Type: application/json; charset=utf-8
ETag: "4a200c9d8fb14925e7461d63b59f4e82"
Server: nginx/1.2.3 + Phusion Passenger 3.0.17
(mod_rails/mod_rack)
Set-Cookie: request_method=GET; path=/
Status: 200
Content-Length: 144
Connection: Close

27. FIXING CACHE-CONTROL.
class FlipsController < ApplicationController
respond_to :json
!
def index
# ...
!
# Last-Modified and ETag
flipbit_etag = Digest::MD5.digest(@flipbit.to_s).to_s
fresh_when last_modified: DateTime.now, etag: flipbit_etag
!
# Cache-Control
expires_in 3.day, :must_revalidate => false, :public => true
# ...
end
end

28. GET /collections/12 HTTP/1.1
Host: app.mycompany.com
!
Cache-Control: max-age=86400, public
Content-Type: application/json; charset=utf-8
ETag: "4a200c9d8fb14925e7461d63b59f4e82"
Server: nginx/1.2.3 + Phusion Passenger 3.0.17
(mod_rails/mod_rack)
Set-Cookie: request_method=GET; path=/
Status: 200
Content-Length: 144
Connection: Close

29. CACHING IS BETTER.
•iOS will honour the cache-control header as long as
there’s cache space.
•Android apache’s HttpClient does not handle
caching, android-query does.

30. CACHING ON
THE DEVICE.

31. NEVER HARD CODE
CACHE LOGIC.

32. MAKE SURE YOU HAVE
ENOUGH STORAGE.

33. CACHE ON iOS.
- (BOOL)application:(UIApplication *)application
didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
NSUInteger mb = 1024*1024;
!
// Configure NSURLCache with larger storage
[NSURLCache setSharedURLCache:
[[NSURLCache alloc] initWithMemoryCapacity:(50*mb)
diskCapacity:(100*mb)
diskPath:nil]
];
!
// ...
// ...
return YES;
}

34. MAKE EVERY
ROUND-TRIP COUNT.

35. BONUS MATERIAL.
Amazon S3 performance.

36. S3 GET PERFORMANCE.
•Make sure you set your Cache-Control headers
using x-amz-meta-Cache-Control.
•Intensive objects benefit from CloudFront by a
factor of 2 or more.

37. S3 PUT PERFORMANCE.
•Avoid sequential keys. S3 stores key names in
alphabetical order; key name dictates which
partition the key is stored in.
http://bit.ly/s3performance

38. AVOID DATES AS PREFIX.
examplebucket/2013-26-05-15-00-00/cust1234234/photo1.jpg
examplebucket/2013-26-05-15-00-00/cust3857422/photo2.jpg
examplebucket/2013-26-05-15-00-00/cust1248473/photo2.jpg
examplebucket/2013-26-05-15-00-00/cust8474937/photo2.jpg
examplebucket/2013-26-05-15-00-00/cust1248473/photo3.jpg
...
examplebucket/2013-26-05-15-00-01/cust1248473/photo4.jpg
examplebucket/2013-26-05-15-00-01/cust1248473/photo5.jpg
examplebucket/2013-26-05-15-00-01/cust1248473/photo6.jpg
examplebucket/2013-26-05-15-00-01/cust1248473/photo7.jpg
...

39. USE HASH AS PREFIX.
examplebucket/232a-2013-26-05-15-00-00/cust1234234/photo1.jpg
examplebucket/7b54-2013-26-05-15-00-00/cust3857422/photo2.jpg
examplebucket/921c-2013-26-05-15-00-00/cust1248473/photo2.jpg
examplebucket/ba65-2013-26-05-15-00-00/cust8474937/photo2.jpg
examplebucket/8761-2013-26-05-15-00-00/cust1248473/photo3.jpg
examplebucket/2e4f-2013-26-05-15-00-01/cust1248473/photo4.jpg
examplebucket/9810-2013-26-05-15-00-01/cust1248473/photo5.jpg
examplebucket/7e34-2013-26-05-15-00-01/cust1248473/photo6.jpg
examplebucket/c34a-2013-26-05-15-00-01/cust1248473/photo7.jpg
...

40. SHARING A BUCKET?
examplebucket/my_beautiful_app/40434b70/avatar.jpg
examplebucket/my_beautiful_app/4ee66b70/avatar.jpg
examplebucket/my_beautiful_app/753da383/avatar.jpg
examplebucket/my_beautiful_app/91255df0/avatar.jpg
examplebucket/my_beautiful_app/98e26030/avatar.jpg
examplebucket/my_very_nice_app/a2cb3fdb/video.mpg
examplebucket/my_very_nice_app/cf763412/video.mpg
examplebucket/my_very_nice_app/d6e93451/video.mpg
examplebucket/my_very_nice_app/e68f7670/video.mpg
...

41. USE SHORT FIXED PREFIX!
examplebucket/mba/40434b70/avatar.jpg
examplebucket/mba/4ee66b70/avatar.jpg
examplebucket/mba/753da383/avatar.jpg
examplebucket/mba/91255df0/avatar.jpg
examplebucket/mba/98e26030/avatar.jpg
examplebucket/mvna/a2cb3fdb/video.mpg
examplebucket/mvna/cf763412/video.mpg
examplebucket/mvna/d6e93451/video.mpg
examplebucket/mvna/e68f7670/video.mpg
...