What Is Oracle9iAS?
Oracle9iAS is Oracle Corporation's integrated Web server. Figure 8.9 illustrates Oracle's Web server technology. This offering from Oracle Corp is a web server and application server combined. Along with processing HTTP/HTML/XML type requests, it can host Oracle Forms, Java, Perl, PL/SQL, and many more engines as well as cache both HTTP and database requests. When a listener receives an HTTP transaction from a Web browser (end user), the transaction is passed to the Oracle/Apache HTTP Server. The HTTP Server then decides what kind of request this is and routes it properly through the Web server to the appropriate facilities. For example, if you are running a Web-based Oracle Form, the request will be routed to the business logic service that is running the Oracle Form itself (as discussed in Chapter 5, “Building Oracle Forms”).
Figure 8.9. Oracle9iAS.
NOTE
Virtual Mappings— The part of the URL that can specify a location after the computer's address. This location is virtual in that it is converted by the Web listener process into a real computer directory location on the computer hosting the Web server. This virtual address can be named anything because it is simply a name to be looked up and converted by the Web listener.
Oracle refers to this technology as 3-tier because the client is the first tier, the iAS is the middle tier, and the database server is the third tier. For scalability and performance reasons, there is no reason that the various components of Oracle9iAS cannot reside on different physical machines in the computing network. Oracle9iAS has many features such as multiple caching mechanisms, high availability features, and redundant features to ensure connectivity. An in-depth look at Oracle9iAS is beyond the scope of this book.