technische universität dortmund service computing service computing prof. dr. ramin yahyapour it...

technische universität dortmund

Service Computing Prof. Dr. Ramin Yahyapour

IT & Medien Centrum12. November 2009


EJB


3

EJB CartBean Example (1)import java.util.*;import javax.ejb.*;

public class CartBean implements SessionBean { String customerName; String customerId; Vector contents;

public void ejbCreate(String person) throws CreateException {

if (person == null) { throw new CreateException("Null person not allowed."); } else { customerName = person; }

customerId = "0"; contents = new Vector(); }

public void ejbRemove() {} public void ejbActivate() {} public void ejbPassivate() {} public void setSessionContext(SessionContext sc) {}

…


4

EJB CartBean Example (2)

… public void addBook(String title) { contents.addElement(title); }

public void removeBook(String title) throws BookException { boolean result = contents.removeElement(title); if (result == false) { throw new BookException(title + "not in cart."); } }

public Vector getContents() { return contents; }

public CartBean() {}

}


5

CartBean –Home Interface

import java.io.Serializable;import java.rmi.RemoteException;import javax.ejb.CreateException;import javax.ejb.EJBHome;

public interface CartHome extends EJBHome {

Cart create(String person) throws RemoteException, CreateException;

}


6

CartBean –Remote Interface

import java.util.*;import javax.ejb.EJBObject;import java.rmi.RemoteException;

public interface Cart extends EJBObject { public void addBook(String title) throws RemoteException;

public void removeBook(String title) throws BookException, RemoteException;

public Vector getContents() throws RemoteException;}


7

Savings Account -Database Definition

CREATE TABLE savingsaccount (id VARCHAR(3) CONSTRAINT pk_savingsaccount PRIMARY KEY, firstname VARCHAR(24), lastname VARCHAR(24), balance NUMERIC(10,2));


8

Savings Account –ejbCreate

public String ejbCreate(String id, String firstName, String lastName, BigDecimal balance) throws CreateException {

if (balance.signum() == -1) { throw new CreateException ("A negative initial balance is not allowed."); }

try { insertRow(id, firstName, lastName, balance); } catch (Exception ex) { throw new EJBException("ejbCreate: " + ex.getMessage()); }

this.id = id; this.firstName = firstName; this.lastName = lastName; this.balance = balance;

return id;}


9

Savings Account –ejbRemove

public void ejbRemove() { try { deleteRow(id); catch (Exception ex) { throw new EJBException("ejbRemove: " + ex.getMessage()); } }}


10

Savings Account –ejbLoad/ejbStore

public void ejbLoad() {

try { loadRow(); } catch (Exception ex) { throw new EJBException("ejbLoad: " + ex.getMessage()); }}

public void ejbStore() {

try { storeRow(); } catch (Exception ex) { throw new EJBException("ejbStore: " + ex.getMessage()); }}


11

Savings Account –Finder Methods

SavingsAccount jones = home.findByPrimaryKey("836");...Collection c = home.findByLastName("Smith");...Collection c = home.findInRange(20.00, 99.00);

public Collection ejbFindByLastName(String lastName) throws FinderException {

Collection result;

try { result = selectByLastName(lastName); } catch (Exception ex) { throw new EJBException("ejbFindByLastName " + ex.getMessage()); } return result;}

For every finder method available to a client, the entity bean class must implement a corresponding method that begins with the prefix ejbFind. The SavingsAccountBean class, for example, implements the ejbFindByLastName method as follows:


12

Savings Account –Finder Methods (2)

public String ejbFindByPrimaryKey(String primaryKey) throws FinderException {

boolean result;

try { result = selectByPrimaryKey(primaryKey); } catch (Exception ex) { throw new EJBException("ejbFindByPrimaryKey: " + ex.getMessage()); }

if (result) { return primaryKey; } else { throw new ObjectNotFoundException ("Row for id " + primaryKey + " not found."); }}

the ejbFindByPrimaryKey method is required other Finder methods are optional


13Winter 2009/10

Lifecycle of a Stateful Session Bean


14Winter 2009/10

Lifecycle of a Stateless Session Bean


15Winter 2009/10

Lifecycle of a Message-Driven Bean


16Winter 2009/10

Lifecycle of an Entity Bean


17Winter 2009/10

Java Application Server


18

Deployment Descriptor

<?xml version="1.0" encoding="UTF-8"?><ejb-jar>

<description>JBoss Hello World Application</description><display-name>Hello World EJB</display-name><enterprise-beans> <session>

<ejb-name>HelloWorld</ejb-name><home>com.mastertech.sample.HelloWorldHome</home><remote>com.mastertech.sample.HelloWorld</remote><ejb-class>com.mastertech.sample.HelloWorldBean</ejb-

class><session-type>Stateless</session-type><transaction-type>Bean</transaction-type>

</session></enterprise-beans>

</ejb-jar>


19

Deployment Descriptorwith Query Definition

<query> <query-method> <method-name>findByName</method-name> <method-params> <method-param>java.lang.String</method-param> </method-params> </query-method> <ejb-ql> select object(p) From CEntityBean2 as p where p.prof = ?1 </ejb-ql></query>


20Winter 2009/10

Message Driven-Beans


21Winter 2009/10

JNDI Architecture


22

JNDI Name Service Example

try { // Create the initial context Context ctx = new InitialContext(env);

// Look up an object Object obj = ctx.lookup(name);

// Print it System.out.println(name + " is bound to: " + obj);

} catch (NamingException e) { System.err.println("Problem looking up " + name + ": " + e);}


23

JNDI Directory Service Example

try {

// Create the initial directory context DirContext ctx = new InitialDirContext(env);

// Ask for all attributes of the object Attributes attrs = ctx.getAttributes("cn=Ted Geisel, ou=People");

// Find the surname attribute ("sn") and print it System.out.println("sn: " + attrs.get("sn").get());

} catch (NamingException e) { System.err.println("Problem getting attribute:" + e);}


24

JNDI Create Context

{ Hashtable env = new Hashtable(); env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.fscontext.RefFSContextFactory");

Context ctx = new InitialContext(env); …}

{ Hashtable env = new Hashtable(); env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.ldap.LdapCtxFactory"); env.put(Context.PROVIDER_URL,

"ldap://localhost:389/o=JNDITutorial"); DirContext ctx = new InitialDirContext(env); …}

technische universität dortmund service computing service computing prof. dr. ramin yahyapour it...

Documents

public cartbean

optional slide

beans slide

public void ejbpassivate

public void ejbactivate

public void ejbstore

public class cartbean

entity bean slide