A set of Java-related software practices and technologies for building enterprise-class applications

Emphasis on availability, security, reliability and scalability

Multi-tiered application model

Enterprises spread across multiple geographic and organization boundaries

Pendulum has swung from data center to desktop to somewhere in-between

Enterprise JavaBeans

Java Servlets Java Server Pages HTTP / HTTPS Java RMI-IIOP JavaIDL JDBC

Java Naming and Directory Interface

JavaMail and Java Activation Framework

Java Messaging Service

Java Transaction API

Partition app construction task by role Shift much of development burden to bean

containers by taking advantage of container services

Select desired services declaratively Support non-persistent (session) and

persistent (entity) usage

Bean provider Container provider Server provider Application assembler Application deployer System administrator

Implicit: distributed transaction management, security, resource management and component lifecycle, persistence, remote accessibility, multiclient support, component location transparency

Explicit: naming and directory services

Java RMI uses Java Remote Method Protocol (JRMP) as its default comm layer

Internet Inter-ORB Protocol (IIOP) is the standard protocol used by CORBA

Provides greater reusability, cross-language use, better integration into legacy systems, firewall navigation and context propagation

Addresses semantic differences between RMI and CORBA relating to distributed garbage collection, object conversion and type mapping

Provides access to most database management systems via SQL

Similar, though not identical to Microsoft ODBC

Provides a unified API for associating names with objects, accessing objects by their names and associating attributes with objects

Acts as an adapter to LDAP, Novell NDS, Sun NFS, Java RMI and both Unix-style and DOS-style file systems

Provides a high-level API for accessing an e-mail system

Uses service providers for SMTP, IMAP, POP3 and other protocols

JAF provides means to describe and display content of varying types

Provides an API for message-based interprocess communications

Supports point-to-point and publish/subscribe models

J2EE provides interfaces; third-party vendors supply implementations (IBM MQSeries, Progress SonicMQ, FioranoMQ)

Low-level API for defining units of work and maintaining the logical integrity thereof

Not explicitly used by EJB programmers

Reference implementation from Sun BEA Systems WebLogic IBM WebSphere Oracle 8i enhydra.org openejb.org

Updates to EJB, Servlet and JSP specs Addition of JAXP, JAAS Addition of message-driven bean type Addition of J2EE Connector Architecture Improvements to container-managed

persistence

Common Object Request Broker Architecture (CORBA)

Microsoft COM/DCOM, COM+, .NET

“Designing Enterprise Applications with the Java 2 Platform, Enterprise Edition”, http://java.sun.com/j2ee/blueprints/

“Mastering EJB” by Roman (Wiley) “Developing Java Enterprise Applications”

by Asbury and Weiner (Wiley) “Java Network Programming” by Harold

(O’Reilly)