Week 3

Day 21

Oracle: The Next
Generation

The purpose of this last lesson is to explore three topics:

• The Oracle Web Application Server, version 3.0—the latest version of Oracle's Web Server that significantly increases the accessibility of an Oracle database from a Web application through the use of cartridges
• Developer/2000 for the Web, release 1.4W—a new release of Developer/2000 that supports the deployment of Forms and Reports applications as both client/server and Web applications
• Oracle's Network Computing Architecture—a major computing initiative that emphasizes the role of the Internet and the World Wide Web, the growing importance of distributed objects, and support for open standards

Also, you probably will want to read Bonus Day 23, "Oracle8: New Features," which discusses new features of the Oracle8 server that are of interest to database designers and application developers.

Connecting an Oracle Database to the
Web: Using Oracle WebServer

In 1995, Oracle Corporation introduced a product that allowed access to an Oracle database from a Web browser: Oracle WebServer. The initial version of WebServer consisted of several components:

• One or more Web Listeners that listened for HTTP connection requests
• Web Agents that connected to a local or remote Oracle database via a specified Oracle account
• Two built-in PL/SQL packages containing procedures and functions that generate HTML tags

Since then, Oracle WebServer has been significantly enhanced. The current version, 3.0, is designed to support the Network Computing Architecture, Oracle's major initiative to provide an open, platform-independent, object-based, Web-based, distributed computing architecture.

Today, you look at the configuration of WebServer 3.0. You also build a few dynamic Web pages through the use of Oracle stored procedures that invoke components of the htp and htf packages.

Elements of the Oracle WebServer

The Oracle WebServer consists of several major components:

• Web Listener: A Web Listener named admin is created during the installation of the product. By default, the admin listener listens on port 8888. A second Web Listener named www is also created during the WebServer installation. By default, the www listener listens on port 80. However, you can modify its configuration, including the ports that it will service.
• Web Request Broker: This program forms the heart of the WebServer product. It dispatches HTTP requests to other WebServer programs, depending on the type of request.

• Database Access Descriptor: A file that describes how a PL/SQL Agent connects to an Oracle database. The Database Access Descriptor includes the name of the Oracle account that is to be used for the connection and the Oracle SID that identifies the database to which the agent will connect. Alternatively, the Database Access Descriptor can describe a SQL*Net2 database alias to be used for the Oracle connection.
• Cartridges: WebServer includes several cartridges, each supporting a different language. Included with the product are cartridges for PL/SQL, Java, Perl, and ODBC (allowing you to access non-Oracle databases via the Oracle WebServer).
• Web Agent: A given cartridge type can support one or more Web Agents. Each Web Agent is associated with a particular Database Access Descriptor that identifies how a connection to an Oracle database is to be made.

The Oracle WebServer must be installed on a server such as Solaris, HP-UX, or Windows NT. After you perform the initial installation, you can complete the installation and configuration with a Web browser. To do this, the initial URL you should use is http://server-name:8888 where server-name is the name of the server, including its domain. As you can see in Figure 21.1, the initial Web page will display nine links that you can choose from.

Figure 21.1.
Initial WebServer
administration page.

If you select the Web Application Server Manager link, another Web page will appear containing three links (see Figure 21.2):

• Oracle Database (enables you to start up or shut down an Oracle database on the server where Oracle WebServer is installed)
• Oracle Web Listener
• Oracle Web Application Server

Figure 21.2.
Viewing the Web
Application Server
Manager.

Web Listener

To configure the Web Listeners, select the Oracle Web Listener link as displayed on Figure 21.2. The page that appears is labeled Oracle Web Listener Administration. If you scroll down on that page, you will see two Web Listeners displayed: admin and www. Both of these Web Listeners are created during product installation. However, the admin Web Listener must be running to perform any other administrative tasks.

You can reconfigure the www Web Listener by selecting the CONFIGURE link. A page, titled Oracle Web Listener Advanced Configuration for Listener www, will appear. If you want to add another Directory Mapping, you can scroll down the frame on the right until you see the heading Directory Mappings. You probably will want to add a directory mapping to this list for each Web Agent that you plan to create. For example, Figure 21.3 displays a directory mapping, /flugle/owa, that will be used for the Flugle College Web agent that will be created shortly. Scroll down to the Modify Listener button and click it. To return to the previous page, you can click the Admin button on the bottom frame.

Figure 21.3.
Creating a directory
mapping for the www
Web Listener.

Web Application Server Administration

To access the Web Application Server Administration page, select the Web Application Server link (as shown previously on Figure 21.2). Another page, titled Oracle Web Applica-tion Server Administration, will appear. As you can see in Figure 21.4, there are nine links displayed on this page: