The document discusses the architecture and implementation of multi-tenancy applications using Java EE, outlining various challenges, strategies, and best practices. It covers tenant identification, UI customization, and database support, along with comparisons of multi-instance vs. multi-tenant frameworks. Additionally, it provides code examples for Java servlets, JSF, CDI, and JPA, illustrating approaches to effectively manage multi-tenant environments.

1. Supporting Multi-tenancy
Applications with Java EE
Rodrigo Cândido da Silva
@rcandidosilva

2. About Me
• Software Architect
• Java Platform
• JUG Leader of GUJavaSC
• http://gujavasc.org
• Twitter
• @rcandidosilva
• Personal
• http://rodrigocandido.me

3. Agenda
• Cloud Services Model
• Multi-tenancy
• Concepts
• Challenges
• Java EE + Multi-tenancy
• Tenant Identification
• UI Customization
• Custom Business Rules
• Database Support
• Demo

4. Cloud Services Model

5. SaaS Market

6. Multi-tenancy
• One application
instance to multiple
clients (tenant)
• Inverse of the multiple
instances architecture

7. Multi-instances vs. Multi-tenant

8. Multi-instances vs. Multi-tenant
Feature Multi-instances Multi-tenant
Cost Structure Can support only flat
pricing
Supports usage based
pricing
Resources Dedicated resources Shared resources
Operation and
Maintenance
Manage and administer
as many instances as
customers
Manager and administer a
single instance for a
number of customers
Scalable Model Not scalable Scalable

9. Cloud and Multi-tenancy

10. Challenges
• Data separation
• UI and business rules customization
• Access control by tenant
• Resource provisioning
• Integrations
• Application update
• Failover tolerance

11. Pros and Cons
• Pros
• Low maintenance cost
• Same source code for all customers
• High scalability
• Sharing resources between customers
• Cons
• High complexity
• Separation by tenant-id
• More failure risks
• If code breaks -> breaks to all customers
• Low flexibility available to the customers

12. Multi-tenancy Concepts
• Adoption levels
• Level 1 (Customized)
• Level 2 (Configurable)
• Level 3 (Scalable)
• Database Strategy
• Separate Databases
• Separate Tables
• Shared Database

13. Level 1 - Customized
• [N] applications and [N] databases

14. Level 2 - Configurable
• [1] application and [N] databases

15. Level 3 - Scalable
• [1] application and [1] database

16. Database Strategy
Separate Databases
Separate Tables
Shared Database

17. Database Strategy
Feature Separate DBs Separate Tables Shared Database
Data
Customization
Security
Inter-dependency
and Performance
Scalable Model
Customer On-
boarding

18. What is the Best Choice?
• Depends on…
• Data Customization
• Addition or removal of columns in the data store
• Function Customization
• The functionality executed for a specific business can vary by
customers
• Process Customization
• The business process can vary for each customer
• Licensing Features
• The product has multiple licenses which define the functionality
that is enabled for the customer

19. Java EE + Multi-tenancy
• Java Servlets
• Tenant Identification
• JavaServer Faces (JSF)
• UI Customization
• Context and Dependency Injection (CDI)
• Custom Business Rules
• Java Persistence API (JPA)
• Database with Multi-tenant Support

20. Java Servlets
• Tenant Identification
• DNS Resolver
• http://customer1.myapp.com
• http://customer2.myapp.com
• Sub-contexts Resolver
• http://www.myapp.com/customer1
• http://www.myapp.com/customer2
• Login Access Resolver

21. Java Servlets
public class TenantRequestListener implements ServletRequestListener {
...
@Override
public void requestInitialized(final ServletRequestEvent
servletRequestEvent) {
final HttpServletRequest request = (HttpServletRequest)
servletRequestEvent.getServletRequest();
loadTenant(request);
}
protected void loadTenant(HttpServletRequest request) {
...
}
}
• DNS and Sub-contexts resolver
public class TenantThreadLocal {
public static final ThreadLocal<String> tenantThreadLocal =
new ThreadLocal<String>();
}

22. JSF + Multi-tenancy
• Flexible software architecture
• Artifacts packaged in separated JAR’s
• Composition at runtime
• Templates and contracts
• Resource library
• Look-and-feel customization
• RenderKit features
• Localization support

23. JSF Facelets

24. JSF Multi-templating
• Resource Library Contracts
• Convention
• All available contracts discovered at startup
• Configuration
• faces-config.xml by <resource-library-contract>
• contracts attribute in <f:view>

25. JSF Multi-templating
<html xmlns="http://www.w3.org/1999/xhtml”
xmlns:h="http://java.sun.com/jsf/html”
xmlns:ui="http://java.sun.com/jsf/
facelets">
<body>
<ui:composition template="#{template}”>
...
</ui:composition>
</body>
</html>
<?xml version="1.0" encoding="UTF-8"?>
<web-app>
<context-param>
<param-name>javax.faces.view.TEMPLATE</param-
name>
<param-value>mybusiness</param-value>
</context-param>
</web-app>

26. CDI + Multi-tenancy
• Custom Business Rules
interface Service {
public void businessMethod();
}
class Customer01Service implements Service {
public void businessMethod() {
...
}
}
class Customer02Service implements Service {
public void businessMethod() {
...
}
}
@Produces
public Service getService() {
switch(currentTenant) {
case "customer01":
return new Customer01Service();
case “customer02":
return new Customer02Service();
}
}

27. CDI + Multi-tenancy
• Method Interceptors
@Interceptor
@Priority(Interceptor.Priority.APPLICATION)
public class MultiTenantInterceptor {
@AroundInvoke
protected Object invoke(InvocationContext ctx) throws Exception {
...
}
}
<beans xmlns="...">
<interceptors>
<class>MultiTenantInterceptor</class>
</interceptors>
</beans>

28. JPA + Multi-tenancy
• There is no standard at this time
• EclipseLink
• Multi-tenancy support using @Multitenant
• Multitenant strategies
• @Multitenant(SINGLE_TABLE) – default
• @Multitenant(TABLE_PER_TENANT)
• @Multitenant(VPD)
• Hibernate
• Supports tenant identifier features
• MultiTenantConnectionProvider
• CurrentTenantIdentifierResolver

29. EclipseLink SINGLE_TABLE
@Entity
@Table(name=“EMP”)
@Multitenant(SINGLE_TABLE)
@TenantDiscriminatorColumn(name = “TENANT_ID”,
contextProperty = “tenant-id”)
public class Employee {
...
}
HashMap properties = new HashMap();
properties.put("tenant.id", "707");
...
EntityManager em = Persistence
.createEntityManagerFactory(
"multi-tenant”,properties)
.createEntityManager();
<persistence-unit name="multi-tenant">
...
<properties>
<property name="tenant.id"
value="707"/>
...
</properties>
</persistence-unit>

30. EclipseLink TABLE_PER_TENANT
<entity class="Employee">
<multitenant type="TABLE_PER_TENANT">
<tenant-table-discriminator type="SCHEMA" context-
property="eclipselink.tenant-id"/>
</multitenant>
<table name="EMP">
...
</entity>
@Entity
@Table(name=“EMP”)
@Multitenant(TABLE_PER_TENANT)
@TenantTableDiscriminator(type=SCHEMA,
contextProperty="eclipselink.tenant-id")
public class Employee {
...
}

31. EclipseLink VPD
@Entity
@Multitenant
@TenantDiscriminatorColumn(name = "USER_ID",
contextProperty = "tenant.id")
@Cacheable(false)
public class Task implements Serializable {
...
CALL DBMS_RLS.ADD_POLICY ('SCOTT',
'TASK', 'todo_list_policy', 'SCOTT',
'ident_func', 'select, update, delete'));
<properties>
<property name="eclipselink.session.customizer"
value="example.VPDSessionCustomizer" />
<property name="eclipselink.session-event-listener"
value="example.VPDSessionEventAdapter" />
<property
name="eclipselink.jdbc.exclusive-connection.mode"
value="Always" />
</properties>

32. Hibernate MultiTenantConnectionProvider
public class MultiTenantProvider
implements MultiTenantConnectionProvider {
public Connection getConnection(String tenantIdentifier)
throws SQLException {
final Connection connection = getAnyConnection();
connection.createStatement().execute(
"SET SCHEMA '" + tenantIdentifier + "'");
return connection;
}
public void releaseConnection(String tenantIdentifier,
Connection connection) throws SQLException {
releaseAnyConnection(connection);
}
}

33. Hibernate CurrentTenantIdentifierResolver
public class SchemaResolver implements
CurrentTenantIdentifierResolver {
@Override
public String resolveCurrentTenantIdentifier() {
return resolveTenant();
}
@Override
public boolean validateExistingCurrentSessions() {
return false;
}
}

34. Hibernate persistence.xml
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/
persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://
java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
<persistence-unit name="default">
<properties>
<property name="javax.persistence.provider"
value="org.hibernate.ejb.HibernatePersistence" />
<property name="hibernate.multiTenancy" value="SCHEMA"/>
<property name="hibernate.tenant_identifier_resolver"
value="SchemaResolver"/>
<property name="hibernate.multi_tenant_connection_provider"
value="MultiTenantProvider"/>
</properties>
</persistence-unit>
</persistence>

35. Demo
• EclipseLink MySports Demo
• http://wiki.eclipse.org/EclipseLink/Examples/MySports
• http://git.eclipse.org/c/eclipselink/examples.git

36. Questions
?

37. References
• http://msdn.microsoft.com/en-us/library/aa479086.aspx
• https://developers.google.com/appengine/docs/java/multitenancy/
• http://www.ibm.com/developerworks/java/library/j-multitenant-java/index.html
• http://www.eclipse.org/eclipselink/documentation/2.4/jpa/extensions/a_multitenant.htm
• http://2012.con-fess.com/sessions/-/details/122/JSF-and-JavaEE-7-for-multi-tenant-
applications
• http://jdevelopment.nl/jsf-22/
• http://picketlink.org
• https://developers.google.com/appengine/docs/java/multitenancy/
• http://www.jboss.org/quickstarts/picketlink/picketlink-authentication-idm-multi-tenancy/
• http://wiki.eclipse.org/EclipseLink/Examples/MySports

38. Thank you!
@rcandidosilva
rodrigocandido.me