Code Notes for J2Ee Ejb, Jdbc, Jsp and Servlets

Chapter 1: Introduction Orientation, History, Background What Is the Java 2 Enterprise Edition (J2EE)? Depending upon whom you ask, Java 2 Enterprise Edition (J2EE) is one of many things. A systems architect might tell you that J2EE is a platform and design philosophy for large enterprise systems. Your local server administrator might tell you that J2EE is a combination of vendor products, WAR, JAR, and EAR files. A developer might tell you that J2EE is marketing spin wrapping up a suite of toolkits. In fact, J2EE comprises three major components. 1. A conceptual definition for enterprise systems architecture. This definition provides a rigorous design philosophy for building large, scalable, web-enabled systems. 2. A collection of API extensions that relate to enterprise systems. These APIs range from e-mail access to database connectivity, bridging concepts as different as distributed computing and web-based applications. 3. A new deployment specification for packaging Java components into a single enterprise solution. Basic Java uses a simple "Java Archive" standard for packaging a set of common class objects into a single deployable file. J2EE extends this concept to Web Archive (WAR) and Enterprise Archive (EAR) formats for deploying larger enterprise systems. This deployment specification includes support for role-based security. History In 1999, Sun announced a fundamental redefinition of the Java platform. Java had originally been designed as an all-encompassing "Write Once, Run Anywhere" system; but Java applications rapidly exploded across a tremendous range of platforms, from smart cards to air conditioners (e.g., www.myappliance.com) to distributed, mission-critical enterprise systems. Obviously, the requirements for an offline payment system on a smart card are vastly different from those of an enterprisewide, web-enabled stock trading platform. Sun initially supported the different platforms by providing a core SDK and an assortment of extension APIs. This approach rapidly became unwieldy, and Sun redefined the Java platform into three distinct versions: Java 2 Micro Edition (for embedded applications such as smart cards), Java 2 Standard Edition (for normal Java applications), and Java 2 Enterprise Edition (for large-scale, distributed, web-enabled applications). The J2EE APIs When the initial J2EE specification was announced, many of the enterprise APIs already existed as independent packages. Thus it is often difficult to tell whether an API is part of Java 2 Enterprise Edition or Java 2 Standard Edition, or is a stand-alone package, or is included in more than one edition. As the various Java editions mature and the literature catches up with the changes in the Java platform, these distinctions should become clearer. The most important J2EE 1.2.1 components are: -JDBC 2.0JDBC is the primary mechanism for using Java to communicate with SQL-compliant databases. J2EE requires the JDBC 2.0 Optional Package, an extension to the core JDBC API included with the Java 2 Standard Edition. Chapter 3 explains the core concepts of JDBC and working with relational databases. -Java Servlets 2.2Servlets are server-side web programs that are primarily gateways between web interfaces and middle-tier components. Servlet technology is an essential component to building secure, scalable web-enabled systems. Chapter 5 covers fundamental Servlet concepts and provides the framework for JavaServer Pages. -JavaServer Pages (JSP) 1.1JavaServer Pages (Chapter 6) extend the power of Servlets by providing a simple mechanism for decoupling web content generation from application and business logic. -Java Naming and Directory Interface (JNDI) 1.2JNDI provides a transparent Java interface to various naming and directory sBrill, Gregory is the author of 'Code Notes for J2Ee Ejb, Jdbc, Jsp and Servlets', published 2002 under ISBN 9780812991901 and ISBN 0812991907.