Chapter 1. Introducing Oracle Application Server

Over the past decade or so, IT environments ”particularly those supporting large amounts of data ”have been moving toward a different kind of overall architecture. In the past, most IT systems were deployed over two primary tiers: a client , which ran the applications, and a server , which hosted the database and some other types of generalized logic and services.

For a number of reasons ”including scalability, availability, and security ”a new tier has been introduced between the client and the server. This middle tier hosts a variety of services that function as intermediaries between the client machines (which act as user interfaces) and the data they use. These services include virtual machines that run application logic, specialized server processes that deliver specific functionality (e.g., reporting or integrating information into portals), and infrastructure services (e.g., handling web communications or caching information for improved performance).

Oracle Application Server consists of a set of components that deliver all this functionality, and more. For example, Oracle Application Server can:

• Respond to HTTP requests

• Run application code

• Provide a security infrastructure

• Supply some specific capabilities, such as business intelligence tools, mobile tools and applications, and a messaging system

• Offer improved performance and response time

• Provide the high availability and scalability needed in an enterprise environment

This book is designed to give you a broad overview of the components that make up Oracle Application Server and how they operate . The goal of the book is to provide you with a clear understanding of the concepts and capabilities of Oracle Application Server, particularly those available in the latest release of the product, Oracle Application Server 10 g . This latest release provides a wide range of functionality, and this book tries to explain what that functionality is, rather than how to implement specific examples. This book isn't merely a description of components, however: it attempts to give you a thorough grounding in the concepts and technology that make up Oracle Application Server 10 g . With this framework, you will be able to understand the full range of the product and more rapidly assimilate the details of the product's implementation.

This first chapter sets the stage for the rest of the book. It provides an introduction to a range of topics, most of which are described in greater detail later in the book. A few of the basics, however ”for example, a brief history of the evolution of "application servers" and Oracle's packaging ”are described only in this chapter, so we encourage you to read it carefully , even if you already have some familiarity with Oracle Application Server.

Before diving into the specific foundations of the product, we'll take a step back to provide some context. We'll discuss why application servers were created and how they evolved, and then we'll move on to introduce the basic features and configurations of Oracle Application Server.