SQL/MX Guide to Stored Procedures in Java (G06.24+, H06.03+)

Introduction

HP NonStop SQL/MX Guide to Stored Procedures in Java—523727-004

1-8

Effect of Invoking an SPJ

When an application issues a CALL statement, the Java method of the invoked SPJ

executes inside a JVM in an SQL/MX UDR server process. Figure 1-3 shows how

SQL/MX processes a CALL statement.

1. An SQL/MX application invokes an SPJ by issuing a CALL statement. The

SQL/MX executor reads the compiled SQL plan for the CALL statement.

2. The SQL/MX executor checks the procedure label to verify that the caller has

permission to invoke the SPJ.

3. If the caller has permission to invoke the SPJ, the SQL/MX executor starts sending

messages to the SQL/MX UDR server (shown as the MXUDR executable in

Figure 1-3) to execute the SPJ. The SQL/MX executor sends any input parameters

that the application passes to the SPJ to the SQL/MX UDR server.

4. Inside the SQL/MX UDR server process, an SPJ class loader loads the class

specified by the SPJ and executes the SPJ method.

5. The SQL/MX UDR server returns the output parameters of the SPJ to the SQL/MX

executor, and the SQL/MX executor returns the output to the application. If

exceptions occur during the execution of the Java method, the SQL/MX UDR

server returns them to the SQL/MX executor as SQL diagnostics.

Figure 1-3. Invoking an SPJ

VST003.vsd

/usr/mydir/Payroll.class

Procedure Label

Application

NonStop

SQL/MX

MXUDR

JVM

SQL Plan

CALL...