1. By: Devesh Sharma

2.  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.

3.  1. Ease of use  2. Lower costs  3. Unlimited storage capacity  4. Highly automated  5. Allows IT to shift focus  6. Scalability

4.  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 Demo

5.  Advantages: ◦ Easy to get started ◦ Automatic Scalability ◦ Reliability, performance and security of Google’s infrastructure ◦ Cost efficient hosting ◦ Risk free trial period

6.  The Mail Java API ◦ App Engine applications can send and receive email messages ◦ The Mail Service Java API supports the JavaMail interface for sending email messages ◦ Example Example  The Users Java API ◦ App Engine applications can authenticate users who have Google Accounts ◦ Example Example  Other services: ◦ Image manipulation, URL fetch, OAuth, etc

7.  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

8.  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

9.  Defining Data classes ◦ Annotations:  @PersistenceCapable  @Persistent ◦ Relationships:  One to One  One to Many ◦ Show Users.java data class in Eclipse

10.  Creating data/Making Objects Persistent ◦ Example:  PersistenceManager pm = PMF.get().getPersistenceManager(); Users user = new Users(“Devesh”, “Sharma”,..); try{ pm.makePersistent(user); }finally{ pm.close(); }

11.  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 results = (List ) query.execute(“Sharma"); if (results.iterator().hasNext()) { for (Users u : results) { //... } } else { //... no results... } } finally { query.closeAll(); }

12.  Updating an Object ◦ Users u = pm.getObjectByID(Users.class, key); U.setFirstName(newFirstName);  Deleting an object ◦ pm.deletePersistent(user);

13.  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 My Admin Console

14.  http://code.google.com/appengine/ http://code.google.com/appengine/  http://code.google.com/appengine/docs/jav a/overview.html http://code.google.com/appengine/docs/jav a/overview.html  What is Cloud computing?. (n.d.). Retrieved from http://www.salesforce.com/cloudcomputing/ http://www.salesforce.com/cloudcomputing/