setEntityContext

• use to set associated entity context
• context is access to runtime entity context ....identify caller, access current transaction state, change state, obtain primary key.

unsetEntityContext

• Container calls before removing instance.

ejbActivate

• same as for session beans

ejbPassivate

• same as for session beans

ejbLoad

• container invokes this method to instruct the instance to synchronize its state by loading it from underlying database.
• BMP: instance variables are refreshed by writting code here to read from the database.
• CMP: container loads the bean's state from the database.

ejbStore

• container invokes this method to instruct the instance to synchronize its state by storing it to the underlying database.
• BMP: write code to update database
• CMP: prepare container-managed fields to be writtent to database.

ejbRemove

• same as for Session bean

ejbCreate

• Container calls after create EJB

ejbPostCreate

• Container calls after ejbCreate()....can use to further initialize bean

findbyPrimaryKey(String key)

• allows client to locate entity beans.
• BMP: define in the home interface and implement a corresponding method that begines with prefix ejbFindByPrimaryKey
• CMP: you DO NOT write this method. GENERATED automatically by the container
• e.g. of use:
  
  StudentLocalHome home = .....;
  StudentLocal student = home.findByPrimaryKey("123445555");

findbyX(Object x)

• allows client to locate entity beans.
• BMP: define in the home interface and implement a corresponding method that begines with prefix ejbFindByPrimaryKey
• CMP: you DO NOT write this method. GENERATED automatically by the container
• e.g. findbyLastName(String lastname)

public class StudentEJB implements EntityBean {

private String studentID; //also primary key
private String firstName;
private String lastName;
private String address;

public String ejbCreate(String s, String f, String l, String a) throws CreateException {

studentID =s;
firstName =f;
lastName = l;
address = a;

Conection con = null
PreparedStatement ps = nu;;

try {

con = getConnection();
ps = con.preparedStatement("insert into students (student_id, "+ " first_name, lastname, address) values (?,?,?,?)");

ps.setString(1, studentID);
ps.setString(1,firstName);
ps.setString(1, lastName);
ps.SetString(1,addresss);

if(ps.executeUpdate() != 1) {

String error = "JDBC did not create any row";
log(error);
thow new CreateException(error);
}

return studentID;
} catch(SQLException sqe) { ....} finally { cleanup(con,ps); }

}

public interface StudentLocalHome extends EJBLocalHome {

StudentLocal create(String studetnID, String name, String password, String address) throws CreateException;

......
}

client creates a new entity object

StudentLocalHome home =

Student student = home.create("1,", "Sam", "password", "123 first ave, Hayward, CA");

public abstract class OrderEJB implements EntityBean {

//get and set methods for cmp fields
public abstract String getOrderID();
public abstract void setOrderID(String id);
public abstract java.sql.Timestamp getOrderDate();
public abstract void setOrderDate(java.sql.Timestamp timestamp);
public abstract String getStatus();
public abstract void setStatus(String status);

public abstract double getAmount();
public abstract void setAmount(double amount);

//get and set methods for relationship fileds
public abstract Collection getLineItems();
public abstract void setLineItems(Collection lineItems);

public abstract StudentLocal getStudent();
public abstract void setStudent(StudentLocal student);

public Stgring ejbCreate(String orderID, StudentLocal student, String status, double amount) throws CreateException {

setOrderID(orderID);
set OrderDate(new java.sql.TImestamp(System.currentTimeMillis()));
setStatus(status);
setAmount(amount);

return null;

}

}

persistent fields

represent and store single unit of data

typically mapped to columns of a table the entity bean is mapped to

container synchronizes the state with the database entry state.

e.g. orderDate, status, amount

How to access: through get* and set* methods in the EJB.

relationahip fields

represents and stores a reference to another entity bean

like "foreign key".

e.g. lineItems, student

Abstract Persistent Schema

located in deployment descriptor

abstract representation of an entity bean's persistent fields and relationship fields.

<cmp-version>2.x</cmp-version>
<abstract-schemap-name>Order</abstract-schema-name>
<cmp-field> <field-name>orderID</field-name> </cmp-field>

<cmp-field> <field-name>orderDate</field-name></cmp-field>

<cmp-field> <field-name> status </field-name></cmp-field>

<cmp-field> <field-name>amount</field-name></cmp-field>

.....

version = 2.x if you want EJB 2.0 container managed persistence

declares 4 container-managed fields

names MUST match the get* and set* methods

EJB Query Language

• new in EJB 2.0
• similar to SQL
• lets you write queries in methods in database independent way.