Oracle Application Server 10g Essentials [Electronic resources] نسخه متنی

Chapter 1. Introducing Oracle Application Server

Over the past decade or so, IT environmentsparticularly those
supporting large amounts of datahave 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 reasonsincluding scalability, availability,
and securitya 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
10g. 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
10g. 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,
howeverfor example, a brief history of the evolution of
"application servers" and
Oracle's packagingare 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.