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Google App Engine
 

Google App Engine

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Google App Engine

Google App Engine

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Assoc.Prof. Dr.Thanachart Numnonda
Asst.Prof. Thanisa Kruawaisayawan

Mini Master of Java Technology
KMITL
July 2012

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    Google App Engine Google App Engine Presentation Transcript

    • Google App EngineAssoc.Prof. Dr.Thanachart Numnonda Asst.Prof. Thanisa Kruawaisayawan Mini Master of Java Technology KMITL July 2012
    • AgendaWhat is Cloud Computing?What is Google App Engine?Google App Engine for JavaGoogle 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 infrastructureDynamic allocation, scaling, movement of applicationsPay per useNo long-term commitmentsOS, application architecture independentNo hardware or software to install
    • Grid to Cloud Evolution
    • Web 2.0 & Cloud ComputingWeb 2,0 concentrate on the private user and clouds are decscendents of data centers which services the enterpriseWeb 2.0 promote SaaSWeb 2.0 needs massive scaling technologiesUser 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 ModelPublic 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: Developers 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 IaaSSource:http://acloudyplace.com/2012/01/comparing-iaas-and-paas-a-developers-perspective/
    • Setting Up App in PaaSSource:http://acloudyplace.com/2012/01/comparing-iaas-and-paas-a-developers-perspective/
    • PaaS for JavaAmazon Elastic BeanstalkCloudBeesCloud FoundryGoogle App EngineHeroku for JavaRed Hat OpenShift
    • PaaS for Java: Comparison
    • PaaS for Java: ComparisonSource: 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 EngineRunning your web application in Google infrastructureSupport different runtime environments Java (JRE 6 with limitation, Servlet 2.5, JDO, JPA) Python (2.5.2)Apps run in sandbox.Automatic scaling and load balancingNo server restart, no network issues
    • Hosting Java web apps traditionallyNot so popular except enterpriseHigh rates as compared to PHP hostingShared Tomcat instance among usersRestrictions on any time deployments due to shared serverDedicated 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/JWas released on April 08 with Python support. Java included on August 09
    • App Engine for Java : One YearSource: What’s Hot in Java for App Engine Google Con 2010
    • GAE Java Runtime EnvironmentJava 6 VMServlet 2.5 ContainerHTTP Session support (need to enable explicitly)JDO/JPA for Datastore APIJSR 107 for Memcache APIjavax.mail for Mail APIjavax.net.URLConnection for URLFetch API
    • Java Standards on GAE
    • Services by App EngineMemcache API – high performance in-memory key-value cacheDatastore – database storage and operationsURLFetch – invoking external URLsMail – sending mail from your applicationTask Queues – for invoking background processesImages – for image manipulationCron Jobs – scheduled tasks on defined timeUser Accounts – using Google accounts for authentication
    • LimitationsProgramming Model : Application runs in sandbox and can not Write to file system Make arbitrary network connections Use multiple threads/processes Perform long-lasting processing Permissions Know about other instances/applicationsQuotas (Requests, In/Out bandwidth, CPU time, API calls)
    • GAE Datastore
    • GAE DatastoreStoring data and manipulationBased on BigtableBigtable is proprietary and hidden from the app developersNot a relational database (No SQL)GQL (Google Query Language) to queryStores data as entitiesDistribution, 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, idThe Development Server simulates Google AccountsAccess constraints based on roles
    • User API : Exampleimport com.google.appengine.api.users.*; import com.google.appengine.api.users.*;UserService userService == UserServiceFactory.getUserService(); UserService userService UserServiceFactory.getUserService();User user == userService.getCurrentUser(); User user userService.getCurrentUser();String navBar; String navBar;if (user == null) {{ if (user == null) navBar == "<p>Welcome! <a href="" ++ userService.createLoginURL("/") navBar "<p>Welcome! <a href="" userService.createLoginURL("/") +"">Sign in or register</a> to customize.</p>"; +"">Sign in or register</a> to customize.</p>";}} else {{ else navBar == "<p>Welcome, "" ++ user.getEmail() ++ "! You can <a href="" navBar "<p>Welcome, user.getEmail() "! You can <a href="" +userService.createLogoutURL("/") +"">sign out</a>.</p>"; +userService.createLogoutURL("/") +"">sign out</a>.</p>";}}
    • URLFetch APIInvoking external URLs from your application over HTTP and HTTPsimport java.net.*; import java.net.*;import java.io.*; import java.io.*;URL url == new URL("htp://..."); URL url new URL("htp://...");InputStream inp == new InputStreamReader(url.openStream()); InputStream inp new InputStreamReader(url.openStream());BufferedReader reader == new BufferedReader(inp); BufferedReader reader new BufferedReader(inp);String line; String line;while ((line == reader.readLine()) != null) {{ while ((line reader.readLine()) != null) //do something //do something}}reader.close(); reader.close();
    • Mail APISend emails on the behalf of app administrator to the Google account use.You can not receive emailsimport javax.mail.*; import javax.mail.*;Session session == Session.getDefaultInstance(new Properties(), null); Session session Session.getDefaultInstance(new Properties(), null);InternetAddress admins == new InternetAddress("admins"); InternetAddress admins new InternetAddress("admins");Message msg == new MimeMessage(session); Message msg new MimeMessage(session);msg.setFrom(admins); msg.setFrom(admins);msg.addRecipient(Message.RecipientType.TO, admins); msg.addRecipient(Message.RecipientType.TO, admins);msg.setSubject("subject"); msg.setSubject("subject");msg.setText("text"); msg.setText("text");Transport.send(msg); Transport.send(msg);
    • Memcache ServiceDistributed in memory cache, better than DataStoreKey-value pair mappingConfigurable expiration time butUnreliable might be vanished at any timeSupported Interfaces : – JACHE (JSR 107: JCACHE – Java Temporary Caching API) – The Low-Level Memcache API
    • Memcache API : Exampleimport static java.util.Collections.emptyMap; import static java.util.Collections.emptyMap;import javax.cache.*; import javax.cache.*;CacheFactory cacheFactory == CacheManager.getInstance().getCacheFactory(); CacheFactory cacheFactory CacheManager.getInstance().getCacheFactory();Cache cache == cacheFactory.createCache(emptyMap()); Cache cache cacheFactory.createCache(emptyMap());cache.put(key, value); cache.put(key, value);cache.get(key); cache.get(key);
    • Task Queues APIPerform background processes by inserting tasks into queues.Instructions need to be mention in file queue.xml, in the WEB-INF/ dirimport com.google.appengine.api.labs.taskqueue.Queue; import com.google.appengine.api.labs.taskqueue.Queue;import com.google.appengine.api.labs.taskqueue.QueueFactory; import com.google.appengine.api.labs.taskqueue.QueueFactory;import com.google.appengine.api.labs.taskqueue.TaskOptions; import com.google.appengine.api.labs.taskqueue.TaskOptions;// ... // ...TaskOptions taskOptions == TaskOptions taskOptionsTaskOptions.Builder.url("/send_invitation_task") TaskOptions.Builder.url("/send_invitation_task") .param("address", "juliet@example.com") .param("address", "juliet@example.com") .param("firstname", "Juliet"); .param("firstname", "Juliet");Queue queue == QueueFactory.getDefaultQueue(); Queue queue QueueFactory.getDefaultQueue();queue.add(taskOptions); queue.add(taskOptions);
    • Cron JobsUp to 20 scheduled tasks per appCron jobs (scheduled tasks) supported in cron.xml in WEB-INF dirSchedule instructions contain Englis-like format<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?><cronentries> <cronentries><cron> <cron><url>/listbooks</url> <url>/listbooks</url><description>Repopulate the cache every day at <description>Repopulate the cache every day at5am</description> 5am</description><schedule>every day 05:00</schedule> <schedule>every day 05:00</schedule></cron> </cron></cronentries> </cronentries>
    • Images APIManipulation of imagesTransformation of imagesChanging 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 GAECommand line tools included.
    • Google Plugin for Eclipse
    • Development EnvironmentDevelopment ServerApplication lifecycle managementEclipse/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 IDEDeploy multiple version of the application at the same timeYour app lives at – <app_id>.appspot.com or – Custom domain with Google Apps
    • Running your app on Googlehttp://<version>.<appid>.appspot.com/some/path
    • Managing ApplicationsAdministration Console http://appengine.google.com/a/yourdomain.comApplication DashboardMultiple application versionsAnalyzing log files (including admin)Analyzing resource usag
    • GAE Dashboard
    • ResourcesGoogle App Engine at a glance, Stefan ChristophDeveloping Java Based Web Applications inGoogle App Engine, Tahir Akram, Dec. 2009Google App Engine, Patrick Chanezon, Mar 2010
    • Thank you thananum@gmail.com twitter.com/thanachartwww.facebook.com/thanachart