Java Programming with Oracle JDBC

Chapter 4. Servlet Database Connections

In this chapter, we’ll explore issues that are specific to using JDBC with servlets. Unlike applets, servlets can use the OCI driver as well as the Thin driver. Like applets, servlets have a distinct life cycle that will impact your selection of a connection strategy. Let’s begin our exploration by examining your driver choices when developing servlets.

Oracle Driver Selection

With servlets, you can use either the OCI driver or the Thin driver. As is the case when developing applications, I recommend you use the Thin driver unless one of the following considerations applies to your work:

• You make heavy use of stored procedures.

• You have the ability to make a Bequeath connection to the database.

For most practical purposes, the Thin driver is just as fast as the OCI driver. One exception is when you execute stored procedures. When stored procedures are invoked, the Thin driver can take up to twice as long as the OCI driver to execute a call. What does this mean in terms of response time? If it typically takes half a second for the OCI driver to make a stored-procedure call, then it will take the Thin driver one second. That’s not much of a problem if you make only one stored-procedure call for each call you make to your servlet. The situation changes, however, if you make multiple stored-procedure calls for each call to your servlet. In such a case, your response time can deteriorate quickly. In our scenario, three stored-procedure calls will lead to a three-second delay. So if your servlets typically make several calls to stored procedures, you should consider using the OCI driver.

The other reason to use the OCI driver is to allow your servlet to make a Bequeath connection to the database. Using the Bequeath protocol results in a direct connection to a dedicated server process that allows your servlet to communicate directly with the Oracle8i database. You bypass the Net8 listener process and eliminate the layer of software associated with TCP/IP. Consequently, a Bequeath connection can result in a significant gain in response time as opposed to a TCP/IP connection. Bequeath connections, however, can be made only in one situation -- your servlet container and your database must reside on the same host.

Now that you understand your options for selecting an Oracle driver for servlet development, let’s examine the life cycle of a servlet to see how it will affect your strategy for making a connection.