Oracle Essentials: Oracle9i, Oracle8i and Oracle8, Second Edition

Oracle as an Internet Server

Oracle is the most popular database server in the world. By adding a few new features to their existing product, Oracle Corporation has been able to position the Oracleserver as the core of the Internet computing environment.

Listener

In order to be able to respond to requests from the Web, the Oracleserver has to have a way to receive requests that come to it over the standard web protocol of HTTP. Starting with Oracle 8.1.7, Oracleincludes a miniversion of iAS. The miniversion of iAS includes the HTTP listener and the connection to the PL/SQL engine, which is called mod_plsql.

When a user calls an Oracleprocedure, the listener uses two types of configuration information: a DAD, which defines the Oracle database and username/password combination used to access the database; and some form of passthrough identifier, which routes the call to a PL/SQL procedure.

The connection to the database is established through the DAD, which identifies the target database and either uses a specific username and password combination or prompts the user for a username and password. Each PL/SQL agent is associated with a DAD, and each DAD can be associated with several agents.

The web listener is configured to listen on a particular port. Requests come in the form of URLs consisting of the name of the server, the port number of the server, the name of the PL/SQL agent that will service the request, and the name of the stored procedure that is to be executed. For instance, ...