google app engine overview - barcamp phnom penh 2011
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Google App Engine
(Google App Engine Overview)
Barcamp Phnom Penh 2011
Phnom Penh, Cambodia
Guy Flysher
About me
● Developer in the Emerging markets team.
● Joined Google in 2007.
● Previously worked on Social graphs,Gmail and Google Accounts.
● Currently work on SMS products (Chat SMS, G+ SMS and more to come...)
● G+ profile: http://gplus.name/GuyFlysher
Agenda
● Part I: What is App Engine?
● Part II: App Engine Product Usage
● Part III: How to use App Engine ○ Hello world example○ App Engine Services○ Code examples○ Demos of non web uses
Why does App Engine exist?
App Engine is a full development platform
Tools
Hosting
APIs
App Engine provides great tools, APIs & hosting
Easy to build Easy to manage Easy to scale
Language Runtime Options
GOJavaExperimental
App Engine APIs/Services
BlobstoreImages
Mail XMPP Task Queue
Memcache Datastore URL Fetch
User Service
Administration Console
Agenda
● Part I: What is App Engine?
● Part II: App Engine Product Usage
● Part III: How to use App Engine ○ Hello world example○ App Engine Services○ Code examples○ Demos of non web uses
App Engine - A Larger Number
1,500,000,000+Page views per day
Notable App Engine Customers
Royal Wedding - Scalability Success
Official blog & live stream apps hosted on App Engine
On Wedding day...Blog app served:
● Up to 2k requests per second● 15 million pageviews ● 5.6 million visitors
Live stream app served:● Up to 32k requests per second● 37.7 million pageviews ● 13.7 million visitors
http://goo.gl/F1SGc
Not all apps user-facing or web-based!
● Need backend server processing? Want to build your own?● Go cloud with App Engine!● No UI needed for app to talk to App Engine, just need HTTP or XMPP● Great place for user info e.g., high scores, contacts, levels/badges, etc.● Better UI: move user data off phone & make universally available
Agenda
● Part I: What is App Engine?
● Part II: App Engine Product Usage
● Part III: How to use App Engine○ Servlets and JSP files○ Hello world example○ App Engine Services and code examples○ Demos of non web uses
Java HttpServlet
● Abstract class for processing HTTP requests.
● Override its methods for processing various HTTP requests, e.g:
○ doGet○ doPost○ doHead○ etc
● Part of Java (not App Engine specific)
HttpServlet example
public class Hello_worldServlet extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
String userIp = req.getRemoteAddr(); resp.setContentType("text/plain"); resp.getWriter().println("Hello, " + userIp); }}
JSP - JavaServer Pages
● Used to create dynamically generated web pages based on HTML.
● A mix of Java and HTML.
● Can be though of as the Java equivalent of PHP.
JSP example
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html><head> <title> Welcome!</title></head><body>
<% if (request.getParameter("name") != null) {%><p>Hello, <%= request.getParameter("name") %> </p><% } else {%><p>Hello, stranger. </p><% }%>
Hello World Demo
Deploy from scratch(In under 3 minutes)
App Engine setup
Servlets and other Java code
JSP, html and other static files
App Engine setup
Configuration files
web.xml
Used to map URLs to the servlets that will handle them:
web.xml
web.xml
Used to map URLs to the servlets that will handle them:
App Engine Services
The User Service
The user system
Building your own user system is a lot of work
● Needs to be very secure - destructive result if broken into.
● Needs to be very reliable - if it is down your app can't be used.
● Lots of other services you need to build - a recovery mechanism etc.
The Google user system
App Engine User Service lets you use Google's user system for your app.Benefits:
● Users don't need to create a new account to use your app, they can use their Google account
● Very secure, highly reliable.
● Already has recovery mechanisms etc.
● Very easy to use!
The User Service
Checking if a user is logged in:<% UserService userService = UserServiceFactory.getUserService(); User user = userService.getCurrentUser(); if (user != null) {%>
<p>Hello, <%= user.getNickname() %> </p>!<p>Our records show your email as: <%= user.getEmail() %> </p>
<% } else {%>
<p>Hello! Please log in. </p>
<% }%>
The User Service
Creating a sign in/out links
<% UserService userService = UserServiceFactory.getUserService(); User user = userService.getCurrentUser(); if (user != null) {%>
<p>Hello, <%= user.getNickname() %>!<p> <a href="<%= userService.createLogoutURL(request.getRequestURI()) %>">Sign out </a></p>
<% } else {%><p><a href="<%= userService.createLoginURL(request.getRequestURI()) %>">Sign in</a</p>...
App Engine Services
The XMPP (chat) Service
Sending a chat message
...
JID fromJid = new JID("gday-chat@appspot.com");JID toJid = new JID("chatty.cathy@gmail.com");Message msg = new MessageBuilder() .withRecipientJids(toJid) .withFromJid(fromJid) .withBody("Hi there. Is this easy or what?") .build(); XMPPService xmpp = XMPPServiceFactory.getXMPPService(); SendResponse status = xmpp.sendMessage(msg); boolean messageSent = (status.getStatusMap().get(toJid) == SendResponse.Status.SUCCESS);
...
App Engine Services
The Mail Service
Sending an email message
...
Properties props = new Properties();Session session = Session.getDefaultInstance(props, null);
try { Message msg = new MimeMessage(session); msg.setFrom(new InternetAddress( "anything@my-app-name.appspotmail.com", "Guy's App Engine App")); msg.addRecipient(Message.RecipientType.TO, new InternetAddress("my.client@gmail.com")); msg.setSubject("You confirmation email"); msg.setText("..."); Transport.send(msg);
} catch (AddressException e) { ... } catch (MessagingException e) { ... } catch (UnsupportedEncodingException e) { ... }
...
Demos
�����!
Q&AMore documentation and information:
http://code.google.com/appengine
Backup
Receiving a chat message
Signup your app to receive chat messages
<inbound-services> <service>xmpp_message</service> </inbound-services>
appengine-web.xml
<servlet> <servlet-name>xmppreceiver</servlet-name> <servlet-class>gday.ReceiveChatMessageServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>xmppreceiver</servlet-name> <url-pattern>/_ah/xmpp/message/chat/</url-pattern> </servlet-mapping>
web.xml
Receiving a chat message
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
XMPPService xmpp = XMPPServiceFactory.getXMPPService(); Message message = xmpp.parseMessage(req);
JID fromJid = message.getFromJid(); String body = message.getBody(); String emailAddress = fromJid.getId().split("/")[0]; if (body.equalsIgnoreCase("hello")) { ... return; }
...
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