Oracle JSQL, JDBC and JAVA Oracle Database Tips by Donald Burleson

Oracle JSQL, JDBC and JAVA

In the previous examples, we didn't deal with JAVA against persistent objects. To use JAVA against persistent objects in Oracle8 you will have to use the JDBC or JSQL protocols.

JDBC

The JDBC protocol sets up a predefined set of classes that allow access to SQL databases. The proper classes must be invoked against the proper database (be it SQLAccess or Oracle, or whatever.)

JSQL

The JSQL protocol is actually a pre-interpreter for JAVA scripts which adhere to the JSQL coding standards. A properly coded JAVA applet (an applet is a standalone section of JAVA code that is treated as an object) or script is fed into the JSQL pre-interpreter which converts all embedded SQL calls into something standard JAVA interpreters can understand. The pre-interpreted JSQL code is then used identically to standard JAVA applets or scripts.

Notice that the oci8 client connection is used in Listing 13.9, other possible values include oci7, and thin. The only valid driver for access of remote databases is thin. The difference between the thin type of driver and the oci7 or oci8 driver is that the thin driver is internally implemented while the others depend on externally defined DLL (Dynamic Link Libraries). This dependence on external files in the oci7 and oci8 drivers results in a security violation for remote database access attempts through JDBC if they are used for that purpose. The thin client is usually used in applets.

To access PL/SQL from within JAVA either the entire PL/SQL script is passed as a single argument, or, an execute call is made against a pre-built PL/SQL stored procedure or function. Obviously the latter is the option of choice because it will reduce the number of network round-trips required to perform the same function improving performance. The appletviewer, included with the JDK download, is used to test and execute applets. An example HTML wrapper used for testing applets is shown in Listing 8.