Using JDBC to Execute Stored Procedures with Output Parameters

PeopleSoft allows developers to execute database stored procedures using PeopleCode that resembles SQLExec("EXEC PACKAGE.PROC_NAME(:1, :2)", &bind1, &bind2);. Even though stored procedures can have input and output parameters, SQLExec discards output parameters. Several years ago I found an interesting post that described how to use DBMS_PIPE with Oracle database to return output parameters, but, it appears the author removed that post. What made the DBMS_PIPE solution so compelling was that it shared the PeopleSoft database connection. The alternative presented below, unfortunately, requires you to maintain a user name and password, preferably encrypted and stored in a secure location. Because of the class loading issues mentioned in my post Using Oracle JDBC from PeopleCode, this post uses the Oracle specific data access classes. If you use a different database, the classes will differ, but the concept is the same. Furthermore, if you use a different database and JDBC driver, you may be able to use the standard, generic JDBC classes as described in the PSST0101 post Writing to Access Databases

Before demonstrating how to call a stored procedure from PeopleCode, we need a stored procedure to call. The following PL/SQL describes a stored procedure that has two parameters: one in and one in/out. The implementation of the procedure hard codes the output value for simplicity.

CREATE OR REPLACE PACKAGE JJM_IN_OUT AS

  PROCEDURE P(
    IN1    IN     VARCHAR2,
    INOUT1 IN OUT VARCHAR2);
END JJM_IN_OUT;
/

CREATE OR REPLACE PACKAGE BODY JJM_IN_OUT AS
  PROCEDURE P(
    IN1    IN     VARCHAR2,
    INOUT1 IN OUT VARCHAR2) IS
  BEGIN
    INOUT1 := 'Hello World';
  END P;
END JJM_IN_OUT;
/
show errors

To build this package, copy the PL/SQL above into a text editor and then run it from SQLPlus. The procedure test follows:

SQL> var out1 varchar2(100)
SQL> exec JJM_IN_OUT.P('x', :out1);

PL/SQL procedure successfully completed.

SQL> print out1

OUT1
-------------------------------------------------------
Hello World

SQL>

The following IScript demonstrates calling a procedure with in/out parameters from PeopleCode:

Function IScript_OutParms()
   Local JavaObject &driver = CreateJavaObject("oracle.jdbc.OracleDriver");;
   Local JavaObject &info = CreateJavaObject("java.util.Properties");
   
   &info.put("user", "dbuser");
   &info.put("password", "secret");
   
   Local JavaObject &conn = &driver.connect("jdbc:oracle:thin:@server:1521:SID", &info);
   Local JavaObject &stmt = &conn.prepareCall("{call JJM_IN_OUT.P (?,?)}");
   Local JavaObject &types = GetJavaClass("java.sql.Types");
   
   REM ** set input parameter values;
   &stmt.setString(1, "aa");
   &stmt.setString(2, "bb");
   
   REM ** register the second parameter as a output parameter;
   &stmt.registerOutParameter(2, &types.VARCHAR);
   
   REM ** execute the SQL statement;
   &stmt.execute();
   
   %Response.SetContentType("text/plain");
   
   REM ** Display the value of the second parameter;
   %Response.WriteLine("JJM_IN_OUT.P output parameter value: " | &stmt.getString(2));
   
   &conn.close();
End-Function;

After making the connection, the code prepares an SQL statement: {call JJM_IN_OUT.P (?,?)}. JDBC procedure calls use the syntax {call proc_name (?,?)} (the question marks represent the procedure's parameters).

The code above is for demonstration purposes only. Be sure to store the database user name and password in a secure manner. When executing SQL using a second connection, be sure to consider deadlock, race conditions, etc.

Using Oracle JDBC from PeopleCode

PSST0101's post Writing to Access Databases demonstrates how to call standard JDBC boiler plate code from PeopleCode. I tried it with the Oracle JDBC driver, but couldn't get the driver to load. First, class.forName kept throwing java.lang.ClassNotFoundException: oracle/jdbc/OracleDriver. Since the intent of class.forName is to register the driver with the JDBC DriverManager, I thought I would see if I could register it manually:

Local JavaObject &driverManager = GetJavaClass("java.sql.DriverManager");
&driverManager.registerDriver(CreateJavaObject("oracle.jdbc.OracleDriver"));

This time the JVM found the class, but, when I executed DriverManager.getConnection, the JVM threw java.sql.SQLException: No suitable driver.

The point of boiler plate JDBC code is to abstract the persistence layer from the code tier, allowing for configurable data repositories. Since PeopleCode requires Java class names as strings, PeopleCode affords us this configurable feature without the JDBC abstraction. Therefore, we can skip the JDBC niceties in favor of direct driver usage:

Local JavaObject &driver = CreateJavaObject("oracle.jdbc.OracleDriver");
Local JavaObject &info = CreateJavaObject("java.util.Properties");

&info.put("user", "john_doe");
&info.put("password", "secret");

Local JavaObject &conn = &driver.connect("jdbc:oracle:thin:@servername:1521:SID", &info);
Local JavaObject &stmt = &conn.createStatement();
Local JavaObject &rs = &stmt.executeQuery("SELECT ROLENAME FROM PSROLEDEFN WHERE ROWNUM < 11");
Local number &rowIdx;

While &rs.next()
   &rowIdx = &rowIdx + 1;
   MessageBox(0, "", 0, 0, "Row " | &rowIdx | " column 1: " | &rs.getObject(1).toString());
End-While;

REM ** Close JDBC resources per Cheryl's comment below;
&rs.close();
&stmt.close();
&conn.close();

Even though I find this example thought provoking, I have not used it in production. When integrating with other applications, I first consider Integration Broker's asynchronous services. Integration Broker provides services such as queuing that aren't available with direct access. If I can't find a delivered target connector and can't create a custom target connector to suit my needs, then my next consideration is Oracle database links.

PeopleSoft's flexible architecture provides developers with a vast array of options. It is important for us as developers to know how and when to use these options.

Update (March 24, 2009)

Nicolas pointed out that users should not hard code user names and passwords. I absolutely agree. The code above is provided as an example. If you implement a solution like this, I strongly encourage you to Encrypt the password and store it somewhere else. PeopleCode has Encrypt and Decrypt functions for this purpose. You can either store the user name and password encrypted in the database or store it in a protected file off line. Furthermore, don't use a privileged user. Use a database user that only has the database access required to accomplish the coded task.

Besides a hard coded password, the code above contains a hard coded SQL string literal. I strongly discourage this practice as well. Use App Designer SQL definitions to store SQL statements. Unlike string literals, PeopleSoft change management tools can search, compare, and maintain managed objects referenced in SQL definitions.

Using JDBC from PeopleCode

PSST0101 wrote a very good example of using JDBC from PeopleCode in a post titled Writing to Access Databases. Even though this example is Microsoft Access specific, you will notice it uses standard JDBC code, and, therefore, could be used to connect to any database that has a JDBC driver. Just make sure you put your target database JDBC driver in your classpath. On a standard app server, that is either $PS_HOME/class or %PS_HOME%\class.