Download Java 2 Platform, Enterprise Edition (J2EE)

Java™ 2 Platform,
Enterprise Edition (J2EE)
Bruno Souza
Java Technologist, Sun Microsystems, Inc.
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Contents
• The Java™ 2 Platform, Enterprise Edition
(J2EE)
• J2EE Environment
• APM and key APM questions
• Application Scenarios and the
Sample Application
• Deployment and Security
• Resources
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A Short History of
Java Enterprise Technology
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The Java™ Platform
Where Have We Been?
Where Are We Going?
Year 1
• JDK All
Things to
Everyone
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Year 2
• JDK “All
Things to the
Enterprise”
• Early
Development
of Consumer
Java
• Early
Development
of “Enterprise”
APIs”
Year 3
• Micro
Edition
• Standard
Edition
• Enterprise
Edition
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Java 2 Platforms
Java Technology
Enabled Devices
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Java Technology
Enabled Desktop
Workgroup
Server
High-End
Server
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Why another Java™ 2 Platform?
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The Global Enterprise
D
EIS Tier
Middle-Tiers
Clients
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D
D
ERP Systems
DBMSs
Enterprise
Services
Device
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Enterprise Services Require
• Concurrency
(multi user)
• Scalability
• Administration
• Consistency
(Transactions)
• EIS Integration
• Security
• Distribution
• Availability
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The Java™ 2 Platform,
Enterprise Edition
• Develop
– With the J2EE App Model
• Deploy
– With the J2EE App unit
• Run
– On the J2EE Platform
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J2EE Platform
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What is the purpose of J2EE
Containers?
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J2EE Platform
HTTP/
HTTPS
JavaMail
JAF
JDBC
JMS
JAF
JNDI
JavaMail
JTA
JMS
App Client
Container
App
Client
JNDI
J2SE
EJB
RMI
RMI/IIOP
Servlet
JSP
JDBC
HTTP/
HTTPS
EJB Container
RMI/IIOP
Applet
Web Container
JTA
Applet Container
J2SE
J2SE
JDBC
RMI/IIOP
JMS
JNDI
RMI
J2SE
Database
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Containers and Components
• The container is the car
• The component is the driver
• The container is the platform
• The component is your application
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J2EE Containers
• Containers do their work invisibly
– No complicated APIs
– They control by interposition
• Containers implement J2EE
– Look the same to components
– Have great freedom to innovate
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J2EE Containers Handle
• Concurrency
(multi user)
• Scalability
• Administration
• Consistency
(Transactions)
• Integration
• Security
• Distribution
• Availability
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J2EE Components Handle
• Presentation
• Business logic
• Data access
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Container Perspectives
• To a J2EE vendor
– It is their product
• To a component developer
– It is a standard app model
• To an app assembler
– It is a standard app package
• To an executing component
– It is god
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Why Does J2EE Focus on
Deployment?
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Application Packaging
EJB
EJB
Module
EJB
1
1
DD
DD
Web Client
Module
2
APP
DD
EJB
WEB
2
WEB
DD
DD
Application
Client Module
3
DD
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Deployment
Tool
DD
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Application Life Cycle
Creation
Created by
Component
Developer
Assembly
Assembled
J2EE Modules and Augmented
by Application
Assembler
Deployment
J2EE APP
Processed
by Deployer
Deploy
J2EE Container
Enterprise
Components
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The Deployer
• Is an expert in the operational
environment
– Familiar with local security practices
– Familiar with local EIS configuration
– Familiar with local containers and their apps
• Uses J2EE platform product tools
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Deployment Summary
• Apps may be written without knowledge
of the operational environment
• Deployment Descriptor communicates
app’s needs
• A key interface between application
developer and platform
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What Exactly Is in J2EE?
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J2EE API Summary
• J2SE 1.2
• JNDI 1.2
• JDBC™ 2.0
• JTA 1.0
• RMI/IIOP 1.0
• JMS 1.0
• EJB 1.1
• JavaMail™ 1.1
• Servlet 2.2
• JAF 1.0
• JSP 1.1
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J2EE Standards
• TCP/IP
• HTTP 1.0
• HTML 3.2
• SSL 3.0
• IIOP 1.0
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The Java™ 2 Platform,
Enterprise Edition
• Platform Specification
– Defines J2EE requirements
• Compatibility Test Suite
– Validates J2EE platform compatibility
• Reference Implementation
– Operational J2EE platform
• Application Programming Model
– Describes how to build J2EE applications
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Java™ 2 Platform, Enterprise Edition
Application Programming Model (APM)
• Organized set of design patterns,
templates and architectural principles
– Focus is on design of manageable, deployable
and maintainable J2EE applications
– Results in faster product delivery time to market
of enterprise solutions
• Recommends how the J2EE specifications
should be applied to application domains
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Some Key APM Questions
• Choose Servlets or JavaServer Pages™
technology (JSP)?
• Access EIS Resources via Enterprise
JavaBeans™ technology (EJB) server
or Directly from JSP?
• Session Beans or Entity Beans?
• Distributed transactions or local
transactions?
• How to exchange Data with
External Systems?
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The J2EE Environment
Enabling End-to-end Solutions
Firewall
Client
Application
Server
Client
Enterprise
JavaBean
Enterprise
Information
Systems (EIS):
Enterprise
JavaBean
Relational-Database,
Legacy Applications,
ERP Systems
Client
Client
Web Server
JSP, Servlet,
HTML, XML
Client
Other Services:
JNDI, JMS,
Java Mail
Client Tier
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Middle Tier
EIS Tier
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Web Access
• Exposes application logic to web client(s)
as coarse grained service(s):
– Responsible for handling “user” input/application
presentation
– Named via URI
– Modeled as HTML (or XML)
• Comprised of dynamic and static content
– Java Server Pages for dynamic content:
• Higher level of abstraction than Servlets
• Easier to generate HTML
(and XML in future)
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“Other” Clients
• EJB from another “application”:
– RMI/IIOP now, JMS later
• Standalone “clients”:
– CORBA client:
• IIOP access direct to application logic
– Java technology client:
• RMI/IIOP or JMS access
– Desktop productivity application:
• MS desktop integration solution via
plug-in, JRE and RMI/IIOP
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Application Logic
• Modeled using EJBs:
– SessionBean (stateless & stateful)
– EntityBean (CMP or BMP)
– Componentize:
• Workflow, processes, business rules and entities…
• Fine grain imperative interface contract
• External resources are logically
named internally
– Customized via deployment descriptor
– Resolved by deployer at deployment time
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Enterprise Information
Services (EIS)
• Integration is achieved by either:
– Directly using platform API such as:
• JDBC™
• JMS
• Java Naming and Directory Interface™ (JNDI)
– Or via Connector(s):
• Connector is:
– Resource adapter, Access Bean,
integration tool(s)
• Ubiquitous Connector APIs for specific
EIS products
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EJB Components
JNDI
EJB Container
Client
Entity EJP
Data Access
Bean
Connector
EIS
Session EJP
Data Access
Bean
Connector
EIS
HTTP(S) Service
Servlet/JSP
Middle Tier
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Application Scenarios
Web Server
App. Server
6
7
1
Web Server
Browser
EIS
Resources
App. Server
Stand-alone
5
2
3
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Core Application Scenarios
1
• n-tier Web Access
– HTML, XML, HTTP client
– JSP/Servlets, RMI/IIOP
– EJBs, JDBC (Connectors)
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Sample
App.
• n-tier Intranet Access
– EJB Client, EJB Sever
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• 2-tier Java Client
– JSP/Servlets and JDBC
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• B2B Enterprise Transactions
– EJBs, JMS and XML
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Sample Application
High Level Requirements
• Must offer Web Presence
• Must be Robust and Scalable
• Must leverage existing EIS resources
• Must utilize core competencies of diverse
development teams
• Must facilitate B2B transactions
• Get it done yesterday!
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Sample Application
High Level Technical Decisions
• Client tier
– Chose HTML Clients for End-User Web Access
– Chose XML for selective Data externalization
• Web Server tier
– Chose JSP/Servlets to be WS neutral
• App Server tier
– Chose EJB’s to be AS neutral
– JDBC Data Access Beans to encapsulate
EIS access
– Chose to optionally support distributed
transactions
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SA—Scenario
• Web-based browsing of a product catalog
• Creation and maintenance of a
shopping cart
• User account creation
• Placing orders
• Secure order processing
– B2B transactions
– Externalization of order data
(expressed in XML)
– Order confirmation using e-mail
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SA—Activity Diagram
Customer
Sales
Warehouse
View Catalog
Add to Cart
Select Account
Process Order
Pull Stock
Ship Order
Receive Order
Bill Customer
Pay Bill
Close Order
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SA—DB Schema
table
table
product
...)
table
...)
lineitem
(
orderid
linenum
itemid
table
orders
(
orderid
userid
...)
...)
table
category
(
suppid
(
productid
category
table
supplier
attrdesc
(
attrcode
(
...)
catid
...)
table
account
(
userid
table
inventoryitem
itemid
productid
supplier
...)
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...)
(
table
orderstatus
(
orderid
linenum
...)
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SA—Architecture
Session Beans
Entity Beans
Access Beans
Tables
Physical
DBs
Account
UserValidatorEJB
AccountEJB
AccountDAB
Orders
MailerEJB
OrderEJB
OrderDAB
OrderStatus
db1
ShoppingCartEJB
Line item
EStoreKeeperEJB
CatalogDAB
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db2
Product
CatalogEJB
InventoryEJB
Category
InventoryDAB
Inventory
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SA—JSP Usage
<html>
<jsp:request include="/banner.html"/>
<form action="validatenewuseraccount.jsp" name="login">
<table border ="0">
<tr><td>User ID:</td>
<td align="left"><input type="text" size="15" name="user_name"></td>
</tr>
<tr><td>Password:</td>
<td align="left"><input type="password" size="15" name =
"password"></td>
</tr>
…..
</table>
</html>
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SA—JSP Usage
<html>
…
<% if (formValid){ %>
<jsp:useBean id="useraccount"
class="com.sunw.estore.account.jspbeans.UserAccountJSPBean"
scope="session" />
<jsp:setProperty name="useraccount" property="init" value="<%= session %>"
/>
<jsp:setProperty name="useraccount" property="billingLastName"
param="last_name" />
...
<% } else { %>
...
<% } %>
</html>
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SA—Controller Interface
public interface EStorekeeper extends EJBObject {
public Catalog
getCatalog()
throws RemoteException;
public ShoppingCart getShoppingCart() throws RemoteException;
public Credential
getCredential()
throws RemoteException;
public Account
getAccount()
throws RemoteException;
public Enumeration getOrders()
throws RemoteException,
FinderException;
public void handleEvent(EStoreEvent se) throws RemoteException;
}
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SA—Controller Implementation
public class EStorekeeperEJB implements SessionBean {
public void ejbCreate() throws RemoteException {
sm = new StateMachine(this);
}
public Catalog getCatalog() throws RemoteException {
Locate Catalog
if (catalog == null) {
EJB’s H/I using JNDI
try {
Context initial = new InitialContext();
Object objref = initial.lookup (EJBUtil.jndiNameOfCatalogHome);
CatalogHome catalogHome = (CatalogHome)
PortableRemoteObject.narrow(objref, CatalogHome.class);
catalog = catalogHome.create();
} catch (NamingException ne) {
...
}
return catalog;
}
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Application Model
• Makes Recommendations across all tiers
–
–
–
–
–
–
–
Client
Middle-tier (includes Web server and EJB)
Data access
Messaging
External application integration
Communication protocols
Deployment file formats
• Results in Faster product delivery
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J2EE Resources
• White paper:
– http://java.sun.com/j2ee
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