Chris Schalk, Developer Advocate, Google Ikai Lan, Developer Programs Engineer, Google Dave Westwood, Creator of BuddyPoke

January 20, 2010

Google App Engine and Social Apps

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Google App Engine

• Easy to build

• Easy to maintain

• Easy to scale

Leveraging Google’s platform to better serve your customers

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Some App Engine Partners

Gartner’s view on Cloud Computing

4 * Source: Yefim Natis, Gartner, AADI 2009

•  Correctly sees App Engine as a “Platform as a Service”

•  Just focus on the code, don’t worry about infrastructure •  Application infrastructure •  System infrastructure

•  Rapid application deployment and change

•  Fully delegated data center responsibility

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App Engine Platform Details

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Specialized services

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Language runtimes

Duke, the Java mascot Copyright © Sun Microsystems Inc., all rights reserved.

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Ensuring Portability

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Extended Language support through JVM

•  Java •  Scala •  JRuby (Ruby) • Groovy • Quercus (PHP) • Rhino (JavaScript) •  Jython (Python)

Duke, the Java mascot Copyright © Sun Microsystems Inc., all rights reserved.

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Application management in the cloud

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App Engine Dashboard

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Development Tools for App Engine

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Google App Engine Launcher

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SDK Console

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Google Plugin for Eclipse

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Feature Roadmap

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Apr 2008 Python launch

May 2008 Memcache, Images API

Jul 2008 Logs export

Aug 2008 Batch write/delete

Oct 2008 HTTPS support

Dec 2008 Status dashboard, quota details

Feb 2009 Billing, larger files

Apr 2009 Java launch, DB import, cron support, SDC

May 2009 Key-only queries

Jun 2009 Task queues

Aug 2009 Kindless queries

Sep 2009 XMPP

Oct 2009 Incoming Email

Dec 2009 Blobstore

18+ months in review

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•  Dashboard •  AppLauncher •  Eclipse Plugin

Demos!

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App Engine as a Social Platform

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App Engine + Social Apps (mobile too!)

•  App Engine works well as a backend server for Social Apps of all types –  OpenSocial

•  Tutorials, example code - “Building an OpenSocial App with Google App Engine”

•  http://wiki.opensocial.org/index.php?title=Building_an_OpenSocial_App_with_Google_App_Engine

–  Facebook •  BuddyPoke

–  Dave Westwood here to speak on his FB implementation of BuddyPoke on GAE

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A social example: BuddyPoke

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A social example: BuddyPoke (on FaceBook)

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BuddyPoke Architecture at a glance

Is an fbml application, with an embedded fb:swf to load the Flash swf file.

Services include:

•  Save avatar appearance •  Hug, Kiss, Poke a friend •  Change mood •  Create & Upload image to FB

Main Functionality

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BuddyPoke User Validation

•  FB automatically passes fb_sig params to the fb:swf file

•  Makes direct calls from the swf file to GAE for Avatar saving functionality (appearance, mood, etc).

•  Pass the fb_sig params along with any http call to GAE

•  GAE then uses fb_sig params to validate any calls from a user

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Making calls to FaceBook

•  fb:swf will have a session key that can be used to make direct calls to Facebook, so a lot of the time you can just do requests straight from Flash -> facebook.

• This is great for things like loading user data, friend data, fql queries etc.

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BuddyPoke User Data in GAE

•  Main ‘User’ data model •  Used 99% of time •  not indexed, no queries, use keys •  key name based on FB id •  fast performance

•  Additional User info model •  Stores additional user info •  ex: install date •  Is indexed, can be queried •  Used less

•  Additional models for: • Virtual currency, blobs for user icons …

Data models for user data

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Storing Unique Icons per User

•  Each user has maximum of N icons to avoid using up too much datastore space.

•  When a user does a hug, poke, changes mood etc, an icon is sent to GAE using multi-part message. The icon will overwrite the previous oldest icon in the datastore and return a unique icon url to use in the feed.

•  Icons are mem-cached, so better performance & saves money!

On FB, a unique icon is generated for each poke/mood change. These icons appear in the feed/wall.

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Updating profile page FBML

•  BuddyPoke has a box on the profile page. It contains fbml that shows icons for the last 4 activities.

• When you hug a friend it will update your profile page, and your friend's profile page. Facebook's servers can be very slow.. So rather than tie up App Engine I create a facebook batch request, sign it on App Engine, and then pass it back to the Flash swf client.

• The client then makes the call to FaceBook's servers with the signed request to update the profile data.

• For OpenSocial, I'd just make the calls directly from App Engine to an OpenSocial server. But if you have 4+ operations to do on facebook those calls can take a long time, so I just get the Flash client to send the request and do all the waiting.

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Updating profile page FBML, cont.

So let's say I wanted to update 20 images on facebook's image caching servers I'd sign a request on App Engine using something like:

def sig_batch_refreshImgSrc(self, urls, call_id): methods = [] for url in urls: sig_param = {} sig_param['url'] = url sig_param['call_id'] = str(call_id) call_id = call_id+1 self._build_post_args("facebook.fbml.refreshImgSrc", sig_param) methods.append(urllib.urlencode(sig_param)) batch_param = {} batch_param['method_feed'] = json.write(methods, True) batch_param['call_id'] = str(call_id) self._build_post_args("facebook.batch.run", batch_param) return '"run":%s' % json.write(batch_param, True)

Then I'd pass that back to the Flash client, and the Flash client can send the request and sit their waiting for 10 seconds while FaceBook forces the image refresh.

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Payments using Paypal

I have Paypal hit App Engine any time there is a new transaction. Paypal will pass a bunch of params, you then ping Paypals server with a _notify-validate using a urlfetch to verify the params came from paypal.

if self.request.get('payment_status') == 'Completed': parameters = self.request.POST.copy() if parameters: parameters['cmd']='_notify-validate’ status = urlfetch.fetch(url = PP_URL, method = urlfetch.POST, payload = urllib.urlencode(parameters) ).content if status == "VERIFIED": ...

Then I'd pass that back to the Flash client, and the Flash client can send the request and sit their waiting for 10 seconds while FaceBook forces the image refresh.

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Communicating with via Email

“Use the email API to send yourself messages about anything important.

Very soon, with the FaceBook changes, I expect I'll be using the email API a lot more.

And the beauty of App Engine is I can just pay for as much email quota as I need. No hassles setting up email servers..”

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Thank you!

code.google.com/appengine

twitter.com/cschalk twitter.com/ikai twitter.com/app_engine