The 1st Java professional open source Convention Israel 2006

Transcription

1 The 1st Java professional open source Convention Israel 2006

2 The Next Generation of EJB Development Frederic Simon AlphaCSP

3 Agenda Standards, Open Source & EJB 3.0 Tiger (Java 5) & JEE What is EJB 3.0 How to use it Page 3

4 Standards and Open Source The open source community relation to specifications and standards. POSIX, JEE (Servlet, EJB,...), XML,... The de-facto standards And now EJB 3.0 Page 4

5 EJB 3.0 Goals Like before: EJB specified the interfaces between application code and JEE container Technical features should be applied separately But: Get the power not the burden The application developers should not deal with the technical code Page 5

6 EJB 3.0 Driving Forces EJB 1.x and 2.0: Too complicated not OO New development concepts: IoC, AOP, POJO JBoss and Hibernate proof Java 5 Page 6

7 EJB 3.0 Status Check the status: Status: In Progress Stage Start Finish Proposed Final Draft 21 Dec, 2005 Public Review Ballot 09 Aug, Aug, 2005 Public Review 27 Jun, Aug, 2005 Early Draft Review 2 08 Feb, Mar, 2005 Early Draft Review 30 Jun, Jul, 2004 Expert Group Formation 10 Jun, Mar, 2004 JSR Review Ballot 27 May, Jun, 2003 Page 7

8 Who is EJB 3.0? JBoss AS EJB 3.0 pack Sun RI GlassFish Oracle EJB3.0 Preview Page 8

9 Agenda Standards, Open Source & EJB 3.0 Tiger (Java 5) & JEE What is EJB 3.0 How to use it Page 9

10 Tiger and the Enterprise What Java 5 brings to JEE: Annotations Generics Performance, Profiler,... Annotations Page 10

11 Tiger and the Enterprise - Annotation (1) public interface HotelBarFacade { public Customer findcustomer(int roomnumber, Date date); public void addbarbill(customer customer, BarBill barbill); There is more information than you would like to see: Metadata This is a facade with a service name The customer is read-only the addbarbill is asynchronous the Customer parameter is just there for it's id Page 11

12 Tiger and the Enterprise - Annotation (2) Before Annotations it will look like: public interface HotelBarFacadeNoAnnotations extends Remote { public CustomerRO findcustomer(int roomnumber, Date date) throws RemoteException; public void addbarbill(int custid, BarBill barbill) throws RemoteException, AsynchronousException; Needs extra XML file for facade name No direct implementation is possible Business Signature contains a lot of technical pollution Page 12

13 Tiger and the Enterprise - Annotation (3) With Annotations it will look = "BarBilling") public interface HotelBarFacadeWithAnnotations public Customer findcustomer(int roomnumber, Date public void addbarbill(@idonly Customer customer, BarBill barbill); Implementation will use the facade directly Business Signature contains no technical pollution Page 13

14 Agenda Standards, Open Source and EJB 3.0 Tiger (Java 5) and JEE What is EJB 3.0 How to use it Page 14

15 What is EJB 3.0 The specification A bunch of annotations (@interface) That's all That's a lot And that's what's great From the Spec: The EJB 3.0 release is focused on a simplification of the Enterprise Java Beans from the developer s point of view. Page 15

16 What is EJB 3.0 The results All the power of a JEE container but: No more home interfaces No more interfaces to extend or implement (EJBObject, SessionBean, EntityBean...) No more deployment descriptors No more checked exceptions And a full O/R Mapping environment for the entity beans (based on Hibernate) Page 16

17 What is EJB 3.0 Stateless Example The Business Interface public interface HotelBarFacade { public Customer findcustomer(int roomnumber, Date date); public void addbarbill(customer customer, BarBill barbill); The public interface HotelBarFacadeBean implements HotelBarFacade { public Customer findcustomer(int roomnumber, Date date) { return customerdao.find(roomnumber,date); public void addbarbill(customer customer, BarBill barbill) { billingmanager.add(customer,barbill); // Dependency Injection code for customerdao and billingmanager Page 17

18 What is EJB 3.0 Stateful Example (1) The Business Interface is the same than stateless: A simple Java Interface The Bean Implementation is also almost identical except for one thing: How EJB 3.0 specifies home.remove() and ejbremove() without a home interface? Page 18

19 What is EJB 3.0 Stateful public class ShoppingCartBean implements ShoppingCart, Serializable { private Map<String,Integer> cart = new HashMap<String,Integer>(); public void buy(string product, int quantity) { cart.put(product, quantity); public Map<String, Integer> getcartcontents() { return public void checkout() { System.out.println("To be implemented"); Page 19

20 Before/After - Stateless and Stateful Size OO Client Before 2-4 Interfaces 1 Class, 1 XML (+vendor specific) Implement or extends javax.ejb.xxx => Extra Classes and Interfaces to keep OO design About 10 lines of code After 1-2 Interface(s) 1 Class Pure Java Classes and Interfaces => Keep OO design Page 20

21 What is EJB 3.0 Entity Beans Migrated from EJB 2.0 abstract class mechanism to a full O/R mapping based on a persistence manager service architecture Client Container EJB Object Home/Bean My EB 2.0 abstract class EJB Container generated class DB My EB 3.0 real class Client Entity Manager DB Page 21

22 What is EJB 3.0 = "CUSTOMER") public class Customer implements java.io.serializable { private int id; private String first; private public int getid() { return = "FIRST") public String getfirst() { return = "LAST") public String getlast() { return last; // Standard constructors with no id // Simple setters for first and last names Page 22

23 Before/After - Entity Size OO Client Before 2-3 Interfaces 1-2 Classes, 1 XML (+vendor specific) Implement or extends javax.ejb.xxx => No OO design More than 10 lines of code for every CRUD operation After 1 Class that can inherit and implements whatever you like Pure Java Classes and Interfaces => Keep OO design Just new XXX(), find, store, delete on EntityManager Page 23

24 Agenda Standards, Open Source and EJB 3.0 Tiger (Java 5) and JEE What is EJB 3.0 How to use it Page 24

25 How to use it Design Time Free your design from previous EJB experience Create the purest OO design possible and then apply annotations to it OO design patterns are more relevant in EJB 3.0 than previous EJB design patterns Page 25

26 How to use it Your Annotations When you master the annotation mechanism, create your own You can then use AOP for a full AADA development methodology Page 26

27 How to use it Callbacks (1) If I need to do something on insert or load of an entity? If I need to do something when a Stateful Bean is removed? How do I receive callbacks from the JEE container? Page 27

28 How to use it Callbacks (2) Answer: Annotations. In EJB 3.0 there are 2 different techniques for solving the callbacks need: Standard Listeners: No technical dependency with the JEE container Interceptors: Need Invocation Context management Annotations advantage: Implement just what you need Page 28

29 How to use it = public class Customer implements java.io.serializable { public class CustomerCallbackListener public void validatecustomer(customer customer) { // Validate Customer before public void addsoaevent(object customer) { // Created Customer add event to ESB system // The same for remove, public void auditaccess(customer customer) { // Increment audit system count Page 29

30 How to use @Interceptors({LifecycleInterceptor.class) public class CustomerDAOBean implements CustomerDAO { // public void postconstructcallback() public void predestroycallback() { public class LifecycleInterceptor public void daoconstructed(invocationcontext ctx) { try { System.out.println("LifecycleInterceptor postconstruct"); ctx.proceed(); catch(exception e) { throw new RuntimeException(e); Page 30

31 How to use public class CustomerDAOBean implements CustomerDAO private EntityManager manager; public int create(string first, String last) { Customer customer = new Customer(first, last); manager.persist(customer); return customer.getid(); public Customer find(int id) { return manager.find(customer.class, id); public List findbylastname(string last) { return manager.createquery("from Customer c where c.last = :last").setparameter("last", last).getresultlist(); public void merge(customer c) { manager.merge(c); Page 31

32 Issues? Performance? Testability? Learning Curve? Page 32

33 Conclusion EJB 3.0 Specification is a Landmark Brings some fresh air to software development (cf Seam Framework) AADA Page 33

34 Your Turn Now Q & A Page 34

35 The 1st Java professional open source Convention Israel 2006