1. Java EE Overview
The problem Java Enterprise Edition attempts to solve: maximize the use of Java technologies by providing a suite of Java technology specifications that is
Integrated
Suitable for enterprise applications
Widely available
Includes all of the basic middleware capabilities for building distributed systems
11/24/2018
Architecture - Comp 650

2. Enterprise applications require
High throughput
Load balancing
Efficient communications
High availability
Highly reliable communications
Persistent, asynchronous communication option
Distributed transactions
High security
Ability to interoperate with whatever
Structured naming with de-centralized administration
11/24/2018
Architecture - Comp 650

3. Trademarks etc
Java, J2EE, J2SE, J2ME, and all Java-based marks are trademarks or registered trademarks of Sun Microsystems, Inc. in the United States and other countries.
Graphics on pages 3, 4, 5 Copyright © Sun Microsystems, Inc. All Rights Reserved.
11/24/2018
Architecture - Comp 650

4. The 3 Cs of Java Enterprise
Components
Containers
Connectors
11/24/2018
Architecture - Comp 650

5. Java Enterprise Overview
11/24/2018
Architecture - Comp 650

6. Presentation technologies
JSP (Java Server Pages)
JSP Standard Tag Library
Servlets
JSPs are compiled into servlets prior to execution
JSF (Java Server Faces)
11/24/2018
Architecture - Comp 650

7. Key middleware services
Communication: RMI-IIOP, JMS, JCA
Naming: JNDI (part of J2SE)
Persistence: JPA, JDBC, JDO
Transactions: EJB, JTA, JTS
Security: (next page)
11/24/2018
Architecture - Comp 650

8. J2SE v1.4 Security Features
JAAS – Java Authentication and Authorization Service
JCE – Java Cryptography Extension
JSSE – Java Secure Socket Extension
Java GSS-API – Kerberos V5 secure communications
Java Certification Path API
11/24/2018
Architecture - Comp 650

9. J2EE for web services Java Architecture for XML Binding (JAXB)
Java API for XML-Based Web Services (JAX-WS)
SOAP with Attachments API for Java (SAAJ)
Java API for XML RESTful Service (JAX-RS) new
Java API for XML Messaging (JAXM)
Java API for XML Processing (JAXP)
Java API for XML Registries (JAXR)
Java API for XML-Based Remote Procedure Call (JAX-RPC)
Two leading registry standards: ebXML Registry and Repository standard, UDDI (Universal Description, Discovery, and Integration)
SOAP was originally part of JAXM
11/24/2018
Architecture - Comp 650

10. Enterprise Java Beans Session beans
Represent business processes and data about an interaction with a client
Two types:
Stateless
Stateful
Entity beans (deprecated, essentially)
Represent persistent data and data integrity rules
Two types of persistence:
Container-managed persistence
Bean-managed persistence
11/24/2018
Architecture - Comp 650

11. Invoking an EJB 2 method JNDI EJB Container Home Object Client EJB3
Request new EJB object 5
Return EJB object reference
Client
EJB
Object 4
Create EJB object 6
Invoke method
JNDI
NS, eg
LDAP
Request home object 1 2
Return home object reference 7
Delegate request to enterprise bean(s)
Enterprise
Bean(s)
11/24/2018
Architecture - Comp 650

12. Message-driven beans MDB are stateless beans that MDB have no
Listen for and handle JMS messages
Participate in transactions if necessary
MDB have no
Home interface
Remote interface
Interfaces directly callable by clients (clients just send messages)
An MDB tutorial
An MDB article
11/24/2018
Architecture - Comp 650

13. If you remember one thing
Enterprise beans are
Single-threaded
Ignorant of security
Ignorant of transactions
Ignorant of networking
The container handles all that
Containers tend to be pricey
11/24/2018
Architecture - Comp 650

14. Leading EJB containers
BEA Weblogic
IBM Websphere
JBoss (open source)
Glassfish (open source)
11/24/2018
Architecture - Comp 650

15. Glassfish demo includes admin console calc-servlet
an EJB that the servlet uses
JAXB for XML response
11/24/2018
Architecture - Comp 650

16. Deployment descriptors
Deferred binding for many of the things the bean developer need not worry about, including
Access control
Transaction requirements
Persistence parameters
Type of bean
Classes used for home and remote interfaces
See pp 418 – 419 for examples
11/24/2018
Architecture - Comp 650

17. EJB roles
Source: Mastering Enterprise JavaBeans, Second Edition, by Ed Roman, Scott Ambler, and Tyler Jewell
11/24/2018
Architecture - Comp 650

18. Web sites (3 of thousands)
Sun’s Java EE site:
(was
Mastering EJB III (downloadable)
EJB design patterns (downloadable)
J2EE Architect’s Handbook (downloadable)
11/24/2018
Architecture - Comp 650

19. JEE and ABC Stakeholders: software community
Developing organization: software vendors
Technical environment:
OO paradigm
Distributed computing
Java
Architects’ experience: varied
Requirements: described earlier
See p 403
11/24/2018
Architecture - Comp 650

20. Tactics used See pp 411-412 Comments on these? 11/24/2018
Architecture - Comp 650

21. Some JEE anti-patterns
Excessive layering
Where are the (really) likely variation points?
Magic Servlet
Instead of “it reads phone numbers from a database and formats the results as HTML,”
Consider a servlet for LDAP interface and a JSP for result formatting
11/24/2018
Architecture - Comp 650

22. More anti-patterns Overstuffed Session
Data should default to request scope
Long-lived data should be in the business tier
Everything is an EJB (“golden hammer”)
EJBs are at their best when
Not using an existing database
Adding transactions
Adding secure remote access
If benefits are not there, DON’T USE EJBs!
11/24/2018
Architecture - Comp 650

23. Yet another anti-pattern
Excessive Round-Tripping
Introduce a Façade that makes lots of calls on the server side and returns a TransferObject
Stateful When Stateless Will Do
Use a client-side adapter to manage arguments
Stateless façade on top of entity beans
Cache data in the client
11/24/2018
Architecture - Comp 650