One-to-One Relationship

Branch Manager1 1

Each branch has a single manager

Each manager manages only one branch

Sue JamesCentral

HeadOffice Tony Dunn

HighStreet Ann Bond

10.1

Implement with a Reference

Branch Manager

myManager

Sue JamesCentral

reference

10.2

Inverse Reference

Branch Manager

myManager

Branch Manager

myBranch

myManager is the inverse reference of myBranch

myBranch is the inverse reference of myManager

10.3

Update Mode

Sue JamesCentral

A reference is set manually in a method

Sue JamesCentral

JADE automatically sets inverse reference

or

or10.4

Referential Integrity

// Suppose mgr1 is Sue James, not currently managing a branch // Suppose mgr2 is Tony Dunn, not currently managing a branch // Suppose br is Central branch, currently without a manager

br.myManager := mgr1; // Manually sets Central's myManager reference to Sue James // Automatically Sue James' myBranch reference set to Central

br.myManager := mgr2; // Manually sets Central's myManager reference to Tony Dunn // Automatically Sue James' myBranch reference set to null // Automatically Tony Dunn's myBranch reference set to Central

delete br; // Manually deletes the Central branch // Automatically Tony Dunn's myBranch reference is set to null

// Suppose mgr1 is Sue James, not currently managing a branch // Suppose mgr2 is Tony Dunn, not currently managing a branch // Suppose br is Central branch, currently without a manager

br.myManager := mgr1; // Manually sets Central's myManager reference to Sue James // Automatically Sue James' myBranch reference set to Central

br.myManager := mgr2; // Manually sets Central's myManager reference to Tony Dunn // Automatically Sue James' myBranch reference set to null // Automatically Tony Dunn's myBranch reference set to Central

delete br; // Manually deletes the Central branch // Automatically Tony Dunn's myBranch reference is set to null

10.5

PersistentTransient

TransientPersistent A persistent object, visible in all nodes, may not

reference a transient object, visible in only one node.

Allow Transient to Persistent Reference

PersistentPersistent

TransientTransient

A transient object may reference a persistent object provided the inverse is not maintained.

An object can reference another object with the same lifetime.

10.6

Relationship Type

PeerPeer

Object is deleted Peer not affected

or

or

ChildParent

Parent is deleted Child is deleted

Child is deleted Parent not affected

10.7

One-to-Many Relationship

Branch Customer1

Each branch has many customers

Each customer belongs to exactly one branch

G.Brown

Central V.Clark

C.Smith

D.Jones

HighStreet

T.Watson

10.8

Implement with a Collection

Branch Customer

allCustomers

exclusive collection

G.Brown

V.Clark

C.Smith

Central

10.9

Inverse Reference

Branch Customer

allCustomers

Branch Customer

myBranch

allCustomers is the inverse reference of myBranch

myBranch is the inverse reference of allCustomers

10.10

Referential Integrity

// Suppose br1 is the Central branch // Suppose br2 is the HighStreet branch // Each branch has a dictionary of customers keyed on ID number // Suppose cust is C.Smith, a customer who is not with any branch

cust.myBranch := br1; // Manually sets the customer's myBranch reference to Central // Automatically adds C.Smith to Central's allCustomers

cust.myBranch := br2; // Manually sets the C.Smith's myBranch reference to HighStreet // Automatically removes C.Smith from Central's allCustomers // Automatically adds C.Smith to HighStreet's allCustomers

cust.myID := '25485725'; // Manually changes C.Smith's key property (ID) // Automatically removes C.Smith from HighStreet's allCustomers // Automatically re-adds C.Smith into allCustomers with a new key

delete cust; // Manually deletes C.Smith // Automatically removes C.Smith from HighStreet's allCustomers

// Suppose br1 is the Central branch // Suppose br2 is the HighStreet branch // Each branch has a dictionary of customers keyed on ID number // Suppose cust is C.Smith, a customer who is not with any branch

cust.myBranch := br1; // Manually sets the customer's myBranch reference to Central // Automatically adds C.Smith to Central's allCustomers

cust.myBranch := br2; // Manually sets the C.Smith's myBranch reference to HighStreet // Automatically removes C.Smith from Central's allCustomers // Automatically adds C.Smith to HighStreet's allCustomers

cust.myID := '25485725'; // Manually changes C.Smith's key property (ID) // Automatically removes C.Smith from HighStreet's allCustomers // Automatically re-adds C.Smith into allCustomers with a new key

delete cust; // Manually deletes C.Smith // Automatically removes C.Smith from HighStreet's allCustomers

10.11

Many-to-Many Relationship

Employee Skill

Each employee has many skills

Each skill is possessed by many employees

F. Mills

DomesticCurrency

J. Wood

ForeignCurrency

MortgageSelling

10.12

Implement with Collections

Employee Skill

allSkills

Employee Skill

allEmployees

allSkills is the inverse reference of allEmployees

allEmployees is the inverse reference of allSkills

10.13

Multiple Inverses

Bank Customer1

allCustomersByAccount myBank

First relationship between Bank and Customer

When a customer’s myBank reference is set manually,the customer is automatically added to both collections

Bank Customer1

allCustomersByName myBank

Second relationship between Bank and Customer

10.14

Conditional Inverses

Branch BankAccount1

allBankAccountsallChequeAccountsallSavingsAccounts

myBranch

SavingsAccountChequeAccount

Three relationships are defined between Branch and BankAccount

Manually setting myBranch for a cheque accountautomatically adds the account to

allBankAccounts and allChequeAccounts

Manually setting myBranch for a savings accountautomatically adds the account to

allBankAccounts and allSavingsAccounts

10.15

Challenge #20

CustomerByLastName 1 Customer

myBank

Bank

allCustomersByLastName

ChequeAccountByNumber 1 BankAccount

myBank

Bank

allChequeAccountsByNumber

SavingsAccountByNumber BankAccount

myBank

Bank

allSavingsAccountsByNumber

1

BankAccountByNumber Customer

allBankAccountsByNumber

1 BankAccount

myCustomer

• Add dictionary classes with duplicate keys not allowed

• Define relationships with collections automatically maintained

10.16

Challenge #21

• Modify ChequeAccount::setPropertiesOnCreate method

• Modify SavingsAccount::setPropertiesOnCreate method

• Modify Customer::setPropertiesOnCreate method

• Code a JadeScript::createCustomerWithBankAccounts method

• Execute the JadeScript and inspect the new objects

10.17

Attributes before References

setPropertiesOnCreate(pAddress : String; pFirstNames : String; pLastName : String) updating;

begin self.myBank := app.myBank; self.address := pAddress; self.firstNames := pFirstNames; self.lastName := pLastName;end;

setPropertiesOnCreate(pAddress : String; pFirstNames : String; pLastName : String) updating;

begin self.myBank := app.myBank; self.address := pAddress; self.firstNames := pFirstNames; self.lastName := pLastName;end;

Why is this method inefficient?

10.18