HTTP and Your Angry Dog

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Ross Tuck HTTP And Your Angry Dog April 13th, Whisky Web

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Who Am I?

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Ross Tuck

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Team Lead at Ibuildings Codemonkey Token Foreigner REST nut

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@rosstuck

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Today's topic:

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Dogs

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HTTP & Dogs

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The Agenda

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Basics

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Client Server Request Response

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POST /gists HTTP/1.1 Authorization: Basic xxxxxxxx Host: api.github.com Content-Length: 146 { "description": "the description for this gist", "public": false, "files": { ... Request

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POST /gists HTTP/1.1 Authorization: Basic xxxxxxxx Host: api.github.com Content-Length: 146 { "description": "the description for this gist", "public": false, "files": { ... Request 2 Parts

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POST /gists HTTP/1.1 Authorization: Basic xxxxxxxx Host: api.github.com Content-Length: 146 { "description": "the description for this gist", "public": false, "files": { ... Request The body

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POST /gists HTTP/1.1 Authorization: Basic xxxxxxxx Host: api.github.com Content-Length: 146 My application ... Request The body

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POST /gists HTTP/1.1 Authorization: Basic xxxxxxxx Host: api.github.com Content-Length: 146 { "description": "the description for this gist", "public": false, "files": { ... Request The body

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POST /gists HTTP/1.1 Authorization: Basic xxxxxxxx Host: api.github.com Content-Length: 146 { "description": "the description for this gist", "public": false, "files": { ... Request

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POST /gists HTTP/1.1 Authorization: Basic xxxxxxxx Host: api.github.com Content-Length: 146 { "description": "the description for this gist", "public": false, "files": { ... Request The headers

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POST /gists HTTP/1.1 Authorization: Basic xxxxxxxx Host: api.github.com Content-Length: 146 { "description": "the description for this gist", "public": false, "files": { ... Request The good stuff

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POST /gists HTTP/1.1 Authorization: Basic xxxxxxxx Host: api.github.com Content-Length: 146 { "description": "the description for this gist", "public": false, "files": { ... Request

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POST /gists HTTP/1.1 Authorization: Basic xxxxxxxx Host: api.github.com Content-Length: 146 { "description": "the description for this gist", "public": false, "files": { ... Request GET, POST, PUT, DELETE

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POST /gists HTTP/1.1 Authorization: Basic xxxxxxxx Host: api.github.com Content-Length: 146 { "description": "the description for this gist", "public": false, "files": { ... Request Key/Value pairs

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POST /gists HTTP/1.1 Authorization: Basic xxxxxxxx Host: api.github.com Content-Length: 146 { "description": "the description for this gist", "public": false, "files": { ... Request

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No content

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HTTP/1.1 201 Created Date: Sun, 09 Sep 2012 11:42:41 GMT Content-Length: 1848 Location: https://api.github.com/gists/a43a0cf58 { "description": "the description for this gist", "comments": 0, "created_at": "2012-09-09T11:42:40Z", ... Response Status code

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Status Codes

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• 2xx • 3xx • 4xx • 5xx OK! Over there! Client screwed up! Server screwed up!

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Content Negotiation

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GET /dogs/corgi HTTP/1.1 Host: api.example.com Request

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HTTP/1.1 200 OK Date: Sun, 26 Aug 2012 18:00:43 GMT { "cute": true, "big": false, "data_dog": true } Response

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HTTP/1.1 200 OK Date: Sun, 26 Aug 2012 18:00:43 GMT true Response

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GET /dogs/corgi HTTP/1.1 Host: api.example.com Request

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GET /dogs/corgi.json HTTP/1.1 Host: api.example.com Request

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/dogs/corgi.json !== /dogs/corgi.xml

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Imagine the URL as your primary key.

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GET /dogs/corgi HTTP/1.1 Host: api.example.com Request

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GET /dogs/corgi?_format=json HTTP/1.1 Host: api.example.com Request

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POST /dogs/corgi?_format=json HTTP/1.1 Host: api.example.com Request

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GET /dogs/corgi HTTP/1.1 Host: api.example.com Request

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GET /dogs/corgi HTTP/1.1 Host: api.example.com Accept: application/json Request

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More POWAH

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GET /dogs/corgi HTTP/1.1 Host: api.example.com Accept: application/json Request

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GET /dogs/corgi HTTP/1.1 Host: api.example.com Accept: application/json, application/xml Request How do I choose?

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No content

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GET /dogs/corgi HTTP/1.1 Host: api.example.com Accept: application/json, application/xml Request

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HTTP/1.1 200 OK Date: Sun, 26 Aug 2012 18:00:43 GMT Content-Type: application/json { "cute": true, "big": false, "data_dog": true } Response

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Nifty.

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GET /dogs/corgi HTTP/1.1 Host: api.example.com Accept: application/json, application/xml Request

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text/html, text/plain

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text/html;key=value, text/plain

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text/html;key=value;foo=bar, text/plain

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text/html, text/plain

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text/html, text/plain;q=0.5 Quality (Default 1.0)

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text/html, text/plain;q=0.5, text/*;q=0.1 Wildcards

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text/html, text/plain;q=0.5, */*;q=0.1 Anything at all

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Accept Headers Little weird...

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But not so scary.

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text/html,application/xhtml+xml, application/xml;q=0.9,*/*;q=0.8

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Cool...

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What the heck is it good for?

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Accept is a “Pattern”

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Accept-Language Accept-Encoding Accept-Charset Accept-Ranges

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Content-Language Content-Encoding (works differently) Content-Range

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Resource vs Representation /dog/corgi JSON, Dutch, Gzipped, /dog/corgi

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Resource vs Representation

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Best way to version your API. Arguably. Right now.

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/v1/dogs/corgi

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Accept: application/vnd.dogipedia-v1+json

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Accept: application/vnd.dogipedia-v2+json

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No content

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No content

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Vary

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Client Server GET /dogs/corgi HTTP/1.1 Host: api.example.com

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Client Server GET /dogs/corgi HTTP/1.1 Host: api.example.com

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Client Server Proxy GET /dogs/corgi HTTP/1.1 Host: api.example.com

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Client Server Proxy GET /dogs/corgi HTTP/1.1 Host: api.example.com Accept: application/json, text/plain User-Species: cat

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Same URL. Different output. WTF should I return?

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Client Server Proxy GET /dogs/corgi HTTP/1.1 Host: api.example.com Accept: application/json, text/plain User-Species: cat

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Client Server Proxy

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Here's how. Hint: Involves the Vary header!

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Client Server Proxy /dogs/corgi Accept: application/json, text/plain User-Species: cat

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HTTP/1.1 200 OK Date: Sun, 26 Aug 2012 18:00:43 GMT Content-Type: application/json Vary: Accept {“json”: “omgz”} Response

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Client Server Proxy URL and Accept? Okay, I got this.

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Some time later...

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Client Server Proxy /dogs/corgi Accept: application/json, text/plain User-Species: aardvark

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Client Server Proxy Valid cache. I has it.

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Client Server Proxy ZZ Z Z Z Z

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HTTP/1.1 200 OK Date: Sun, 26 Aug 2012 18:00:43 GMT Content-Type: application/json Vary: Accept {“json”: “omgz”} Response

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HTTP/1.1 200 OK Date: Sun, 26 Aug 2012 18:00:43 GMT Content-Type: application/json Vary: Accept, User-Species {“json”: “omgz”} Response

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HTTP/1.1 200 OK Date: Sun, 26 Aug 2012 18:00:43 GMT Content-Type: application/json Vary: Accept, User-Species {“json”: “dogs rule, cats drool”} Response

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Request headers. Not Response!

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Bad Reputation? 2 Reasons

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1. Accept-Encoding -Language

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2. Internet Explorer

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Caching

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Expires Pragma Cache-Control

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Expires Pragma Cache-Control

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Expires Cache-Control HTTP 1.0 HTTP 1.1

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HTTP/1.1 200 OK Expires: Thu, 07 Feb 2013 22:00:00 GMT {“herp”: “derp”} Response

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HTTP/1.1 200 OK Cache-Control: max-age=120 {“herp”: “derp”} Response

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HTTP/1.1 200 OK Cache-Control: max-age=120 Response

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Expires Cache-Control HTTP 1.0 HTTP 1.1

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HTTP/1.1 200 OK Cache-Control: max-age=120 {“herp”: “derp”} Response

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HTTP/1.1 200 OK Cache-Control: max-age=120, s-maxage=120 {“herp”: “derp”} Response Dude, Where's my dash?

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public private no-store no-cache no-transform must-revalidate proxy-revalidate

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Mark Nottingham's Caching Tutorial http://www.mnot.net/cache_docs/ Much better than me.

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Conditional Requests

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Conditional Requests

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The Part About ETags

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Conditional Requests

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DELETE /ross/reputation HTTP/1.1 Host: api.joind.in If-Talk-Quality: Crap Request

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if ($talkQuality === 'Crap') { delete($rossReputation); } Not real code Server

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What kind of conditions?

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If-Match If-None-Match If-Modified-Since If-Unmodified-Since If-Range ETags Datetimes Either

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Wait a second, Ross. Audience

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What the heck is an ETag, anyways?

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A string. Any string.

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One rule:

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Represent the current state.

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“14” “a381bedb5d4478053eb04be35f8798dd” “winnie-the-pooh”

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...for the current representation.

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etag(“v14-json-en”) !== etag(“v14-xml-en”) Don't cross the streams Server

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Last Modified Date sounds easier... Audience

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Wed, 15 Nov 1995 04:58:08 GMT One second of precision

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Caching With Conditionals

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Use Case

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GET /gists/3481910 HTTP/1.1 Host: api.github.com Accept: */* Request

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HTTP/1.1 200 OK Server: nginx/1.0.13 Date: Sun, 26 Aug 2012 18:00:43 GMT Vary: Accept ETag: "f4e15911542b92b44bb38186e71cc8f5" "history": [ { "version": "529f6311d5518977534b6e1fd313...", ... Response

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... "user": { "gravatar_id": "c26bfcbd5f786591e036fa0", "avatar_url": "https://secure.gravatar...", "login": "rosstuck", "url": "https://api.github.com/users/rosstuck", "id": 146766 }, "change_status": { "additions": 1, "deletions": 0, "total": 1 }, Response

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"url": "https://api.github.com/gists/348...", "committed_at": "2012-08-26T17:40:03Z" } ], "git_pull_url": "git://gist.github.com/34819...", "forks": [ ], "html_url": "https://gist.github.com/3481910", "git_push_url": "[email protected]:3481910.git", "comments": 0, "user": { Response

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No content

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HTTP/1.1 200 OK Server: nginx/1.0.13 Date: Sun, 26 Aug 2012 18:00:43 GMT Vary: Accept ETag: "f4e15911542b92b44bb38186e71cc8f5" { "history": [ { "version": "529f6311d5518970903cb5427534b6e1fd313aca", "user": { "gravatar_id": "c26bfcbd5f786591e036fa0958a11e8b", "avatar_url": "https://secure.gravatar.com/avatar/c26bfcbd5f786591e036fa0958a11e8b?d=https://a2... "login": "rosstuck", "url": "https://api.github.com/users/rosstuck", "id": 146766 }, "change_status": { "additions": 1, "deletions": 0, "total": 1 }, "url": "https://api.github.com/gists/3481910/529f6311d5518970903cb5427534b6e1fd313aca", "committed_at": "2012-08-26T17:40:03Z" } ], "git_pull_url": "git://gist.github.com/3481910.git", Response "forks": [ ], "html_url": "https://gist.github.com/3481910", "git_push_url": "[email protected]:3481910.git", "comments": 0, "user": { "gravatar_id": "c26bfcbd5f786591e036fa0958a11e8b", "avatar_url": "https://secure.gravatar.com/avatar/c26bfcbd5f78659....",} "login": "rosstuck", "url": "https://api.github.com/users/rosstuck", "id": 146766 }, "public": true, "created_at": "2012-08-26T17:40:03Z", "files": { "gistfile1.txt": { "type": "text/plain", "filename": "gistfile1.txt", "raw_url": "https://gist.github.com/raw/3481910/8b6946739e8098408ee3af96... "content": "Hello PFC!", "language": null, "size": 10 } }, "description": "", "url": "https://api.github.com/gists/3481910", "updated_at": "2012-08-26T17:40:03Z", "id": "3481910" }

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No content

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GET /gists/3481910 HTTP/1.1 Host: api.github.com Accept: */* If-None-Match: "f4e15911542b92b44bb38186e71cc8f5" Request

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HTTP/1.1 304 Not Modified Server: nginx/1.0.13 Date: Sun, 26 Aug 2012 18:00:43 GMT Vary: Accept ETag: "f4e15911542b92b44bb38186e71cc8f5" Response

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HTTP/1.1 304 Not Modified Server: nginx/1.0.13 Date: Sun, 26 Aug 2012 18:00:43 GMT Vary: Accept ETag: "f4e15911542b92b44bb38186e71cc8f5" Response

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HTTP/1.1 304 Not Modified Server: nginx/1.0.13 Date: Sun, 26 Aug 2012 18:00:43 GMT Vary: Accept ETag: "f4e15911542b92b44bb38186e71cc8f5" Response No giant body!

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Caching. You has it.

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GET /gists/3481910 HTTP/1.1 Host: api.github.com Accept: */* If-None-Match: "a381bedb5d4478053eb04be35f8798dd" Request

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GET /gists/3481910 HTTP/1.1 Host: api.github.com Accept: */* If-None-Match: "ross-is-a-poo-poo-head" Request

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HTTP/1.1 200 OK Server: nginx/1.0.13 Date: Sun, 26 Aug 2012 18:00:43 GMT Vary: Accept ETag: "f4e15911542b92b44bb38186e71cc8f5" "history": [ { "version": "529f6311d5518977534b6e1fd313...", Response

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Recap

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No ETag Old ETag Matching ETag Full Body Full Body No Body → → →

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...on supported servers.

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Why?

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Parsing Bandwidth Response time Probably ...Maybe

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However...

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“The fastest request is one you don't make.” - Jesus

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More Fun With ETags

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Optimistic Concurrency Control “Record Versioning”

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Request

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GET /gists/3481910 HTTP/1.1 Host: api.github.com Accept: */* If-None-Match: "f4e15911542b92b44bb38186e71cc8f5" Request

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PATCH /gists/3481910 HTTP/1.1 Host: api.github.com Accept: */* If-None-Match: "f4e15911542b92b44bb38186e71cc8f5" Request

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PATCH /gists/3481910 HTTP/1.1 Host: api.github.com Accept: */* If-Match: "f4e15911542b92b44bb38186e71cc8f5" Request

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PATCH /gists/3481910 HTTP/1.1 Host: api.github.com Accept: */* If-Match: "f4e15911542b92b44bb38186e71cc8f5" { "description": "cheese om nom nom" } Request

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Response

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Response HTTP/1.1 200 OK Server: nginx/1.0.13 Date: Sat, 01 Sep 2012 14:01:38 GMT ETag: "899b76047a5e68445668374c2e0faa32" { "description": "cheese om nom nom", "user": { "login": "rosstuck", ...

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It works.

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So what?

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What if I send something...

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No content

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PATCH /gists/3481910 HTTP/1.1 Host: api.github.com Accept: */* If-Match: "899b76047a5e68445668374c2e0faa32" { "description": "cheese om nom nom" } Request

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PATCH /gists/3481910 HTTP/1.1 Host: api.github.com Accept: */* If-Match: "stay-puft-marshmellow-dog!" { "description": "cheese om nom nom" } Request

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HTTP/1.1 412 Precondition Failed Server: nginx/1.0.13 Date: Sun, 26 Aug 2012 18:00:43 GMT Response

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Response

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if (“stay-puft-marshmellow-dog” == “f4e1591..”) { patchTheRecord(); } Server

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if (“stay-puft-marshmellow-dog” == “f4e1591..”) { patchTheRecord(); } else { sendScary412Message(); } Server

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Your ETag is out of date.

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“Two guys on the same record” problem

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Other Scary Precondition Errors

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Disclaimer New Stuff Ahead

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DELETE /gists/3481910 HTTP/1.1 Host: api.github.com Request

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HTTP/1.1 428 Precondition Required Server: nginx/1.0.13 Date: Sun, 26 Aug 2012 18:00:43 GMT Response

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Am I operating on the latest version?

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DELETE /gists/3481910 HTTP/1.1 Host: api.github.com Request

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DELETE /gists/3481910 HTTP/1.1 Host: api.github.com If-Match: "f4e15911542b92b44bb38186e71cc8f5" Request

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HTTP/1.1 204 No Content Server: nginx/1.0.13 Date: Sun, 26 Aug 2012 18:00:43 GMT Response