1.5 Database Connection Features
The connection between the client and
the database server is a key component of the overall architecture of
a computing system. The database connection is responsible for
supporting all communications between an application and the data it
uses. Oracle includes a number of features that establish and tune
your database connections.The following features relate to the way the Oracle database handles
the connection between the client and server machines in a database
interaction. We've divided the discussion in this
section into two categories: database networking and Oracle
Application Server.
1.5.1 Database Networking
Database users connect to the database by establishing a network
connection. You can also link database servers via network
connections. Oracle provides a number of features to establish
connections between users and the database and/or between database
servers, as described in the following sections.
1.5.1.1 Oracle Net
Oracle's network interface,
Oracle Net, was
formerly known as Net8 when used in Oracle8, and SQL*Net when used
with Oracle7 and previous versions of Oracle. You can use Oracle Net
over a wide variety of network protocols, although TCP/IP is by far
the most common protocol today.Features associated with Oracle Net, such as shared servers, are
referred to as Oracle Net Services.
1.5.1.2 Oracle Names
Oracle Names
allows clients to connect to an Oracle server without requiring a
configuration file on each client. Using Oracle Names can reduce
maintenance efforts, because a change in the topology of your network
will not require a corresponding change in configuration files on
every client machine.
1.5.1.3 Oracle Internet Directory
The Oracle Internet Directory (OID)
was introduced with Oracle8i. OID serves the
same function as Oracle Names in that it gives users a way to connect
to an Oracle Server without having a client-side configuration file.
However, OID differs from Oracle Names in that it is an LDAP
(Lightweight Directory Access Protocol) directory; it does not merely
support the Oracle-only Oracle Net protocol.
1.5.1.4 Oracle Connection Manager
Each connection to the database takes up
valuable network resources, which can impact the overall performance
of a database application. Oracle's Connection
Manager, illustrated in Figure 1-3, reduces the number of Oracle Net
client network connections to the database through the use of
concentrators,
which provide connection multiplexing to implement multiple
connections over a single network connection. Connection multiplexing
provides the greatest benefit when there are a large number of active
users.
Figure 1-3. Concentrators with Connection Managers for a large number of users

You can also use the Connection Manager to provide multiprotocol
connectivity when clients and servers run different network
protocols. This capability replaces the multiprotocol interchange
formerly offered by Oracle, but it is less important today because
most companies use TCP/IP as their standard protocol.Oracle Database 10g introduces dynamic Connection Manager
configuration, enabling changing of CMAN parameters without shutting
down the CMAN process.
1.5.1.5 Advanced Security Option
The Advanced Security Option was once known
as the Advanced Networking Option (ANO). Key features include network
encryption services using RSA Data Security's RC4 or
DES algorithm, network data integrity checking, enhanced
authentication integration, single sign-on, and DCE (Distributed
Computing Environment) integration.
1.5.1.6 Label Security Option
Oracle Label Security controls access
to data by comparing labels assigned to data with label
authorizations granted to users. Multiple authorization levels are
possible within a single database. Label security authorizations are
managed through the Policy Manager. Policies are enforced in the
database instead of through views, thus greatly simplifying
management of data accessibility and providing a more secure
implementation.
1.5.1.7 Availability
Advanced networking features such as the Oracle Connection Manager,
Advanced Security Option, and Label Security Option have typically
been available for the Enterprise Edition of the database, but not
for the Standard Edition.
1.5.2 Oracle Application Server
The popularity of Internet and intranet applications has led to a
change in deployment from client/server (with fat clients running a
significant piece of the application) to a three-tier architecture
(with a browser supplying everything needed on a thin client). The
Oracle Application Server provides a means of implementing the middle
tier of a three-tier solution for web-based applications,
component-based applications, and enterprise application integration.
Oracle9iAS
and Oracle Application
Server 10g (referenced here together as Application Server) replaced
a previous Oracle Application Server (OAS) and Oracle Web Application
Server. Oracle's Application Server can be scaled
across multiple middle-tier servers.This product includes a web listener based on the popular Apache
listener, servlets and JavaServer Pages (JSPs), business logic,
and/or data access components. Business logic might include
JavaBeans, Business Components for Java (BC4J), and Enterprise
JavaBeans (EJBs). Data access components can include JDBC, SQLJ,
BC4J, and EJBs.
TopLink provides a
mapping tool that links Java objects to the database via JDBC such
that the Java developer need not build SQL calls and or face broken
Java applications due to database schema changes.
Oracle's Application
Server offers additional solutions in the cache, portal,
intelligence, and wireless areas:Cache
Oracle
Application Server Web Cache introduced a middle tier for the caching
of web pages or portions of pages. An earlier cache, Oracle
Application Server Database Cache, was used for caching PL/SQL
procedures and anonymous PL/SQL blocks but is no longer supported
with Oracle Application Server 10g.
Portal
The Oracle
Application Server Portal is also a part of the Oracle Developer
Suite (discussed later in this chapter) and is used for building
easy-to-use browser interfaces to applications through servlets and
HTTP links. The developed portal is deployed to the Application
Server.
Business Intelligence
Application Server Business Intelligence components include the
Portal, but also:Oracle Reports, which provides a scalable middle tier for the
reporting of prebuilt query resultsOracle Discoverer, for ad hoc query and relational online analytical
processing (ROLAP)A deployment platform for OLAP and data mining applications
custom-built with JDeveloper
These capabilities are discussed in Chapter 9.
Wireless
Oracle Wireless
Edition (formerly known as Oracle Portal-to-Go) includes:
Content adapters for transforming content to XMLDevice transformers for transforming XML to device-specific markup
languagesPersonalization portals for service personalization of alerts, alert
addresses, location marks, and profiles; the wireless personalization
portal is also used for the creation, servicing, testing, and
publishing of URL service and for user management
1.5.2.1 Availability
Because Oracle Application Server is a separate product, it can be
used with various versions of the Oracle database and with either
edition.The Application Server packaging includes a Standard Edition, an
Enterprise Edition, and a Java Edition (including key components for
Java developers). Portal and
TopLink are included in the Standard
Edition. The Enterprise Edition adds the following capabilities:
Forms Services, Reports Services, Discoverer Viewer, Oracle Internet
Directory, Oracle Workflow, and Oracle Application Interconnect. The
Java Edition bundle includes a HTTP Server, OC4J, TopLink, BC4J, and
JDeveloper. For more details about Application Server, see Chapter
14.