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By: Devesh Sharma Why Cloud Computing? ◦ Traditional Business Applications Expensive Complicated Difficult to manage Idea behind Cloud Computing ◦ Instead of organizations running their business applications by themselves in-house, run them on shared data centers. 1. Ease of use 2. Lower costs 3. Unlimited storage capacity 4. Highly automated 5. Allows IT to shift focus 6. Scalability Actors: Parents and Teacher Features: ◦ Application and database hosted on Google App Engine ◦ Developed Front End using Servlets and JSP’s ◦ Developed Back End using Google App Engine (non relational) datastore Demo Advantages: ◦ Easy to get started ◦ Automatic Scalability ◦ Reliability, performance and security of Google’s infrastructure ◦ Cost efficient hosting ◦ Risk free trial period The Mail Java API The Users Java API Other services: ◦ App Engine applications can send and receive email messages ◦ The Mail Service Java API supports the JavaMail interface for sending email messages ◦ Example ◦ App Engine applications can authenticate users who have Google Accounts ◦ Example ◦ Image manipulation, URL fetch, OAuth, etc Not a relational database, Object Oriented database instead Datastore stores and performs queries over data objects, known as entities An entity has one or more properties App Engine Java SDK includes implementations of the Java Data Objects (JDO) and Java Persistence API (JPA) interfaces Interaction with the datastore using a PersistenceManager object, obtained from PersistenceManagerFactory object Setting up a PersistenceManagerFactory instance takes time to initialize. Therefore, an app should reuse a single instance. An easy way: wrap it in singleton class, PMF.java Demo – PMF.java on Eclipse Defining Data classes ◦ Annotations: @PersistenceCapable @Persistent ◦ Relationships: One to One One to Many ◦ Show Users.java data class in Eclipse Creating data/Making Objects Persistent ◦ Example: PersistenceManager pm = PMF.get().getPersistenceManager(); Users user = new Users(“Devesh”, “Sharma”,..); try{ pm.makePersistent(user); }finally{ pm.close(); } Queries in App Engine: ◦ JDO includes a query language (JDOQL) for retrieving objects that meet a set of criteria. ◦ Query query = pm.newQuery(Users.class); query.setFilter("lastName == lastNameParam"); query.declareParameters("String lastNameParam"); try { List<Users> results = (List<Users>) query.execute(“Sharma"); if (results.iterator().hasNext()) { for (Users u : results) { // ... } } else { // ... no results ... } } finally { query.closeAll(); } Updating an Object ◦ Users u = pm.getObjectByID(Users.class, key); U.setFirstName(newFirstName); Deleting an object ◦ pm.deletePersistent(user); Use admin console to: Create a new application Add other people as developers View error logs and analyze traffic Blacklist IP addresses or subnets – DoS protection service ◦ Browse your application’s datastore and manage indexes ◦ Test new versions of your application, and switch the version that users see ◦ ◦ ◦ ◦ My Admin Console http://code.google.com/appengine/ http://code.google.com/appengine/docs/jav a/overview.html What is Cloud computing?. (n.d.). Retrieved from http://www.salesforce.com/cloudcomputing/