1. Google App Engine Google APIs OAuth Facebook Graph API
Twitter Bootstrap
Google Developer Group
Presentation & Albertian Institute of Science & Technology – 19th October 2013
Shashidhar Gurumurthy

2. Agenda Session Objectives App Engine Overview Environment Setup
App Engine Services
OAuth
Google APIs
Facebook APIs
References
Play on shashi-demo.appspot.com

3. Session Objectives Describe App Engine & its offerings
Get you started on App Engine development using Java
Usage of commonly used App Engine services
OAuth
Working with Google APIs
Working with Facebook APIs
Help you develop your first App Engine application and use few Google & Facebook APIs

4. Session Objectives – Prerequisites
Familiarity with Servlet development using a Servlet container such as Tomcat is assumed
Some familiarity with Eclipse IDE
That’s it… that’s all you need to get started on developing awesome apps with Google App Engine.
Objectives

5. Session Objectives – What’s not covered
Google App Engine applications can be written in Python and Go programming languages as well. This session uses Java.
All Services provided are not covered due to time constraints
Objectives

6. So… what is Google App Engine
Overview
Google App Engine lets you:
Run web applications on Google’s infrastructure
Easy to build, maintain and scale
No servers to maintain – just upload your application
Costs nothing to get started:
All applications get a free limit on resources
When billing is enabled for an application, free limits are raised but you still pay only for resource usage above free levels
Applications run in a secure environment with limited access to underlying operating system
Applications can only access other computers on the internet through provided URL Fetch and services
Applications cannot write to the file systems
Application code only runs in response to a web request, queued task or a scheduled task

7. The Java Runtime Environment
Overview
Java runtime environment uses Java 6 (Java 7 support is experimental with SDK )
App Engine Java SDK supports Java 5 or 6
Java Servlet and JSPs
The SDK provides implementations of Java Data Objects (JDO) & Java Persistence API (JPA) interfaces for interaction with App Engine Datastore
JavaMail API can be used to send mail with App Engine Mail service
java.net.HTTP APIs access the App Engine URL Fetch service

8. Development Workflow
Overview
App Engine SDK includes tools for local emulation of App Engine services
SDK includes tools for uploading application to App Engine
The App Engine admin console is the web-based interface for managing applications running on the App Engine. Use it to:
Create new apps
Configure domain names
Change which version of application is live
Examine logs
Browse application datastore
View Memcache
App Engine Console

9. App Engine Information on web
Environment Setup
Setup
Install Java SDK (1.7 or 1.6) – 1.7 is experimental and available on App Engine SDK only
If using Eclipse, install Google Plugin for Eclipse
If not using Eclipse, download App Engine Java SDK
In this case you will also need Apache Ant to enable you to interact with App Engine via command line interface – we will not cover this case.
Setup details:
App Engine Information on web

10. Services – Users
Services
App Engine applications can authenticate using one of three methods:
Google Accounts
Accounts on Google Apps Domains
OpenID identifier – federated authentication
Application can access a signed in user’s address (or OpenID identifier)
The app can detect whether the current user is an administrator

11. Services – Datastore
Services
The App Engine Datastore is a schemaless object datastore
The Datastore holds data objects known as entities
Each entity is identified by its kind which categorizes the entity for the purpose of queries, and a key that uniquely identifies it within its kind
The Datastore can execute multiple operations in a single transaction
While the Datastore interface has similar features as traditional relational databases, it differs in the way it describes relationships between data objects
Entities of the same kind can have different properties

12. Services – Java Datastore API
The App Engine Java SDK provides a low-level Datastore API with simple operations on entities
The SDK also includes implementation of the Java Data Objects (JDO) and Java Persistence API (JPA) interfaces for modeling and persisting data
App Engine Datastore service is a large area of study
We will briefly review JDO for persisting and querying entities

13. Services – Scheduled Tasks
The App Engine Cron Service allows scheduling of tasks that operate at defined times or regular intervals
A Cron job will invoke a URL using an HTTP GET request at a given time of day
A cron.xml file in WEB-INF directory of the application controls cron
The Admin Console allows you to view the state of your cron jobs
The dev appserver does not automatically run the cron jobs

14. Services – Mail App Engine applications can send email messages
Apps can receive s at various addresses
Apps send messages using the Mail service
Apps receive messages in the form of HTTP requests initiated by App Engine and posted to the app
The Mail service Java API supports the JavaMail interface for sending messages
The development server does not send messages

15. Services – URL Fetch
Services
App Engine applications can fetch resources and communicate with other hosts over the internet using HTTP & HTTPS requests
Apps use URL Fetch service to make requests
The URL Fetch service uses Google’s network infrastructure for efficiency and scaling purposes
Apps use java.net.URLConnection and related classes to make connections

16. Services – Task Queues
Services
Applications can perform work outside of a user request.
The application adds tasks to task queues to be executed later
Two types of queues:
Push Queues function within App Engine environment.
Configure a queue and add tasks to it. App Engine handles the rest.
Pull Queues allows consumers inside or outside of App Engine environment to process tasks
In this case application needs to scale workers based on processing volume

17. Services – Google Cloud Storage
The Google Cloud Storage offers another method for your application to store and serve data
Similar to AWS S3
Access via a RESTful API as well as Cloud Storage Java API for Google App Engine

18. Services – Memcache Distributed in-memory data cache
Speed up common datastore queries
If many requests make the same query with the same parameters, app can cache the results in memcache

19. Services – Multitenancy
Multitenancy refers to a software architecture whereby one instance of an application serves many client organization
Namespaces API allows you to compartmentalize Google App Engine data
App Engine supports Namespaces in the following APIs
Datastore
Memcache
Task Queue

20. Services – Google Cloud Endpoints
Consists of tools, libraries and capabilities to generate endpoints and client libraries from an App Engine backend to simplify client access to that back end.
Introduced in Feb 2013 with SDK 1.7.5

21. Services – Others App Identity
Identifying itself
Asserting identity to Google APIs and other systems
Blobstore: Datastore allows blobs of max 1M. For storing larger objects, use Blobstore
Channel: Use to create persistent connection to send messages to Javascript client in real time.
Images: Manipulate image data using dedicated image service
Logs: Provides access to request and application logs
OAuth: Use App Engine application as OAuth service provider
Capabilities, Search, Prospective Search & XMPP (IM)

22. Google APIs & OAuth
Google provides access to many of its services via APIs
You can use these APIs within your applications
Most of the APIs require authenticated access; OAuth provides the authentication mechanism
OAuth also provides a mechanism to gain access to private data via scoped authorization
Steps to use Google API:
Define a project on Google API console
Select the required services
Create OAuth client id ( & secret)
Use the OAuth flow to get access token
Send Access token in request header of the HTTP call to Google API
OAuth Playground
Google APIs Console

23. Google OAuth Flow (for Web Server Applications)

24. Facebook API Usage Similar access mechanism as Google API
Uses OAuth for authorization
Steps to use Facebook API:
Define a Facebook App on developers.facebook.com
This gives you App ID & App Secret
Use the App ID & App Secret along with required permissions to get access token
Send Access token as request parameter in the HTTP call to Facebook API
Facebook Developers

25. What else do I need? Something to make the UI look better
Frameworks for responsive client
Best ones to start with
jQuery
Twitter Bootstrap
Some More
Mustache Templates
jQuery Mobile

26. Demo – Sample Starter Applications
Starter Apps which you can use to begin developing App Engine application using Google APIs or Facebook APIs
Google API used – Calendar API to get Calendar list
Facebook API used – Get logged in user’s profile
How to use?
To learn, copy/paste piece by piece into a new App Engine project OR
Import whole project and enhance / modify

27. Environment Setup Create App Engine Project & Deploy Use Google and/or
Let’s Play
Environment Setup
Create App Engine
Project & Deploy
Use Google and/or
Facebook API
In Your Project

28. References
Google App Engine Home:
App Engine Java Home:
App Engine Admin Console:
Google APIs Console:
Google OAuth documentation & flow:
OAuth Playground:
Facebook Developers:
Demo Source Code:
Google APIs starter project: ect.zip
Google + Facebook APIs starter project: ookStartupProject.zip