Java Web Programming on Google Cloud Platform [1/3] : Google App Engine
-
Upload
imc-institute -
Category
Technology
-
view
1.144 -
download
2
description
Transcript of Java Web Programming on Google Cloud Platform [1/3] : Google App Engine
Google App Engine
Assoc.Prof. Dr.Thanachart NumnondaAsst.Prof. Thanisa Kruawaisayawan
www.imcinstitute.comJuly 2012
Agenda
What is Cloud Computing?What is Google App Engine?Google App Engine for JavaGoogle App Engine Development cycle
What is Cloud Computing?
Cloud computing : Definition (Wikipedia)
Cloud Computing is Internet-based computing, whereby shared resources, software, and information
are provided to computers and other devices on demand, like the electricity grid.
Cloud computing characteristics
Massive, abstracted infrastructureDynamic allocation, scaling, movement of applicationsPay per useNo long-term commitmentsOS, application architecture independentNo hardware or software to install
Grid to Cloud Evolution
Web 2.0 & Cloud ComputingWeb 2,0 concentrate on the private user and clouds
are decscendents of data centers which services the enterprise
Web 2.0 promote SaaSWeb 2.0 needs massive scaling technologiesUser centric Web 2.0 companies (Twitter, Slideshare)
are relying on Cloud Services
ISP to Cloud Evolution
Software as a Service (SaaS)SaaS is at the highest layer and features a complete
application offered as a service, on-demand,via multitenancy — meaning a single instance of the
software runs on the provider’s infrastructure and serves multiple client organizations.
Platform as a Service (PaaS)The middle layer, or PaaS, is the encapsulation of a
development environment abstraction and the packaging of a payload of services
PaaS offerings can provide for every phase of software development and testing, or they can be specialized around a particular area, such as content management
Infrastructure as a Service (IaaS)IaaS is at the lowest layer and is a means of delivering basic
storage and compute capabilities as standardized services over the network.
Servers, storage systems, switches,routers, and other systems are pooled (through virtualization technology, for example) to handle specific types of workloads — from batch processing to server/storage augmentation during peak loads.
Deployment ModelPublic Cloud: provider refers to the cloud platform that
targets any types of customers.Private Cloud: infrastructure that’s hosted internally, targeting
specific customers or sometimes exclusively within an organization.
Hybrid Cloud: the combination of public and private clouds, or sometimes on-premise services.
IaaS & PaaS: Developer's Perspectives IaaS normally provides up to O/S level as your choice; for
example Amazon Web Services (AWS) offers several types of Operating Systems such as Windows Server, Linux SUSE, and Linux Red Hat. Developer need to install own middleware, database, etc.
PaaS, given that the database server, VM, and web server VM are readily provisioned,
Setting Up App in IaaS
Source:http://acloudyplace.com/2012/01/comparing-iaas-and-paas-a-developers-perspective/
Setting Up App in PaaS
Source:http://acloudyplace.com/2012/01/comparing-iaas-and-paas-a-developers-perspective/
PaaS for JavaAmazon Elastic BeanstalkCloudBeesCloud FoundryGoogle App EngineHeroku for JavaRed Hat OpenShift
PaaS for Java: Comparison
PaaS for Java: Comparison
Source: http://www.infoq.com/articles/paas_comparison
What is Google App Engine?
Google App Engine : Definition (Wikipedia)
It is a platform for hosting web applications in Google-managed data centers. It is cloud computing
technology which virtualizes applications across multiple servers and data centers.
Google App EngineRunning your web application in Google infrastructureSupport different runtime environmentsJava (JRE 6 with limitation, Servlet 2.5, JDO, JPA)Python (2.5.2)
Apps run in sandbox.Automatic scaling and load balancingNo server restart, no network issues
Hosting Java web apps traditionallyNot so popular except enterpriseHigh rates as compared to PHP hostingShared Tomcat instance among usersRestrictions on any time deployments due to shared
serverDedicated hosts works fine but they are costly
You end up with all this
Google Datacenters at Dallas, Oregon
GAE Architecture
GAE Physical Deployment Diagram
Architecture : Application Server
Distributed web hosting platform
Distributed Datastore
Distributed memcache
Specialized services
Google Apps + your apps
Google App Engine for Java
GAE/JWas released on April 08 with Python support. Java
included on August 09
App Engine for Java : One Year
Source: What’s Hot in Java for App Engine Google Con 2010
GAE Java Runtime EnvironmentJava 6 VMServlet 2.5 ContainerHTTP Session support (need to enable explicitly)JDO/JPA for Datastore APIJSR 107 for Memcache APIjavax.mail for Mail APIjavax.net.URLConnection for URLFetch API
Java Standards on GAE
Services by App EngineMemcache API – high performance in-memory key-value cacheDatastore – database storage and operationsURLFetch – invoking external URLsMail – sending mail from your applicationTask Queues – for invoking background processesImages – for image manipulation Cron Jobs – scheduled tasks on defined timeUser Accounts – using Google accounts for authentication
LimitationsProgramming Model : Application runs in sandbox and
can notWrite to file systemMake arbitrary network connectionsUse multiple threads/processesPerform long-lasting processingPermissionsKnow about other instances/applications
Quotas (Requests, In/Out bandwidth, CPU time, API calls)
GAE Datastore
GAE Datastore
Storing data and manipulationBased on BigtableBigtable is proprietary and hidden from the app developers Not a relational database (No SQL)GQL (Google Query Language) to query Stores data as entitiesDistribution, replication, load balancing behind the scene Need to use JDO/JPA
User Service : Google Accounts
Google Accounts are encouraged as the preferred authentication mechanism for App Engine– It assumes that all users have a Google Account – Google authentication for private domains isn’t available yet
Access to Google account data -> email, idThe Development Server simulates Google AccountsAccess constraints based on roles
User API : Example
import com.google.appengine.api.users.*;
UserService userService = UserServiceFactory.getUserService();
User user = userService.getCurrentUser();
String navBar;
if (user == null) {
navBar = "<p>Welcome! <a href=\"" + userService.createLoginURL("/") +"\">Sign in or register</a> to customize.</p>";
} else {
navBar = "<p>Welcome, " + user.getEmail() + "! You can <a href=\"" +userService.createLogoutURL("/") +"\">sign out</a>.</p>";
}
import com.google.appengine.api.users.*;
UserService userService = UserServiceFactory.getUserService();
User user = userService.getCurrentUser();
String navBar;
if (user == null) {
navBar = "<p>Welcome! <a href=\"" + userService.createLoginURL("/") +"\">Sign in or register</a> to customize.</p>";
} else {
navBar = "<p>Welcome, " + user.getEmail() + "! You can <a href=\"" +userService.createLogoutURL("/") +"\">sign out</a>.</p>";
}
URLFetch APIInvoking external URLs from your application over HTTP and
HTTPs import java.net.*;
import java.io.*;
URL url = new URL("htp://...");
InputStream inp = new InputStreamReader(url.openStream());
BufferedReader reader = new BufferedReader(inp);
String line;
while ((line = reader.readLine()) != null) {
//do something
}
reader.close();
import java.net.*;
import java.io.*;
URL url = new URL("htp://...");
InputStream inp = new InputStreamReader(url.openStream());
BufferedReader reader = new BufferedReader(inp);
String line;
while ((line = reader.readLine()) != null) {
//do something
}
reader.close();
Mail APISend emails on the behalf of app administrator to the Google
account use.You can not receive emails import javax.mail.*;
Session session = Session.getDefaultInstance(new Properties(), null);
InternetAddress admins = new InternetAddress("admins");
Message msg = new MimeMessage(session);
msg.setFrom(admins);
msg.addRecipient(Message.RecipientType.TO, admins);
msg.setSubject("subject");
msg.setText("text");
Transport.send(msg);
import javax.mail.*;
Session session = Session.getDefaultInstance(new Properties(), null);
InternetAddress admins = new InternetAddress("admins");
Message msg = new MimeMessage(session);
msg.setFrom(admins);
msg.addRecipient(Message.RecipientType.TO, admins);
msg.setSubject("subject");
msg.setText("text");
Transport.send(msg);
Memcache Service
Distributed in memory cache, better than DataStore Key-value pair mappingConfigurable expiration time butUnreliable might be vanished at any timeSupported Interfaces :– JACHE (JSR 107: JCACHE – Java Temporary Caching API)– The Low-Level Memcache API
Memcache API : Example
import static java.util.Collections.emptyMap;
import javax.cache.*;
CacheFactory cacheFactory = CacheManager.getInstance().getCacheFactory();
Cache cache = cacheFactory.createCache(emptyMap());
cache.put(key, value);
cache.get(key);
import static java.util.Collections.emptyMap;
import javax.cache.*;
CacheFactory cacheFactory = CacheManager.getInstance().getCacheFactory();
Cache cache = cacheFactory.createCache(emptyMap());
cache.put(key, value);
cache.get(key);
Task Queues APIPerform background processes by inserting tasks into queues.Instructions need to be mention in file queue.xml, in the WEB-INF/ dir
import com.google.appengine.api.labs.taskqueue.Queue;
import com.google.appengine.api.labs.taskqueue.QueueFactory;
import com.google.appengine.api.labs.taskqueue.TaskOptions;
// ...
TaskOptions taskOptions =
TaskOptions.Builder.url("/send_invitation_task")
.param("address", "[email protected]")
.param("firstname", "Juliet");
Queue queue = QueueFactory.getDefaultQueue();
queue.add(taskOptions);
import com.google.appengine.api.labs.taskqueue.Queue;
import com.google.appengine.api.labs.taskqueue.QueueFactory;
import com.google.appengine.api.labs.taskqueue.TaskOptions;
// ...
TaskOptions taskOptions =
TaskOptions.Builder.url("/send_invitation_task")
.param("address", "[email protected]")
.param("firstname", "Juliet");
Queue queue = QueueFactory.getDefaultQueue();
queue.add(taskOptions);
Cron JobsUp to 20 scheduled tasks per appCron jobs (scheduled tasks) supported in cron.xml in WEB-INF dirSchedule instructions contain Englis-like format
<?xml version="1.0" encoding="UTF-8"?>
<cronentries>
<cron>
<url>/listbooks</url>
<description>Repopulate the cache every day at
5am</description>
<schedule>every day 05:00</schedule>
</cron>
</cronentries>
<?xml version="1.0" encoding="UTF-8"?>
<cronentries>
<cron>
<url>/listbooks</url>
<description>Repopulate the cache every day at
5am</description>
<schedule>every day 05:00</schedule>
</cron>
</cronentries>
Images API
Manipulation of imagesTransformation of imagesChanging image formats
GAE Development Cycle
GAE Development Cycle
Getting Started
The application owner must have a Google Account to get the tools regardless of language.
Use Java 6 for development.Eclipse and Netbeans have official plugins.Both SDKs ship with a Development Web Server that
runs locally and provides a sandbox almost identical to the real run-time.
Software Development Kit
App Engine SDK– Includes web server (Jetty)–Emulates all the GAE services
SDK includes an upload tool to deploy app to GAECommand line tools included.
Google Plugin for Eclipse
Development Environment
Development ServerApplication lifecycle
managementEclipse/NetBeans plugins /
Firefox plugin (GWT).
Google Plugin for Eclipse
Development Server
http://localhost:8888
Development Server Admin Console
http://localhost:8888/_ah/admin
Deployment Environment
Application is deployed as .war which contains.Deployment is integrated in IDEDeploy multiple version of the application at the same
timeYour app lives at–<app_id>.appspot.com or–Custom domain with Google Apps
Running your app on Google
http://<version>.<appid>.appspot.com/some/path
Managing Applications
Administration Console http://appengine.google.com/a/yourdomain.comApplication DashboardMultiple application versionsAnalyzing log files (including admin)Analyzing resource usag
GAE Dashboard
ResourcesGoogle App Engine at a glance, Stefan ChristophDeveloping Java Based Web Applications in Google App Engine, Tahir Akram, Dec. 2009Google App Engine, Patrick Chanezon, Mar 2010