3.  Integration

This example demonstrates the calling of OpenVMS native routines from Java, as well as the manipulation of data structures. The original program is an example PL/I application called PHONE (not to be confused with the OpenVMS PHONE utility). It is a simple progam that presents an example for file I/O and screen management as a phone book.

For the purpose of demonstrating the integration utilities the file access routines were extracted and put into a run-time library. A Java-Swing application was then developed that uses this RTL to access and update the phone book file.

The main objectives were to:

• move the application to a Java-Swing based frontend,
• re-use the existing file access routines,
• avoid any major changes to the original application,
• allow the original application to continue being used in parallel with the new Java application.

All of these objectives were met and the whole process is demonstrated in the article, Calling Native OpenVMS Routines from Java.

A backup saveset containing the full source for both the PL/I and Java-Swing applications can be downloaded here. The saveset is also available inside a ZIP file here.

The following build instructions, as well as building the PHONE utility, also build the run-time library necessary to implement the jPhone utility shown below.

$ TYPE BUILD_PHONE.COM
$ PLI PHONE
$ PLI DATABASE
$ PLI SCREEN
$ LINK/SHARE=DATABASE_RTL.EXE,SYS$INPUT/OPTION
SYMBOL_VECTOR = ( -
    OPEN_PHONEBOOK = PROCEDURE, -
    CLOSE_PHONEBOOK = PROCEDURE, -
    GET_A_RECORD = PROCEDURE, -
    GET_A_MONTH_RECORD = PROCEDURE, -
    GET_A_DATE_RECORD = PROCEDURE, -
    WRITE_A_RECORD = PROCEDURE, -
    DELETE_A_RECORD = PROCEDURE -
    )
$ DEFINE/NOLOG DATABASE_RTL SYS$DISK:[]DATABASE_RTL
$ LINK PHONE,SCREEN,SYS$INPUT/OPTIONS
DATABASE_RTL/SHARE
$ IF (F$SEARCH("PHONE.DAT") .EQS. "") THEN CREATE/FDL=PHONE.FDL
$ EXIT 1
$ @BUILD_PHONE.COM

$ TYPE BUILD_JPHONE.COM
$ set noon
$ on control_y then goto bail_out
$
$ set process/parse_style=extended
$ define/nolog decc$efs_case_preserve enable
$ define/nolog decc$efs_case_special enable
$ define/nolog decc$efs_charset enable
$ define/nolog decc$argv_parse_style enable
$
$ jc = "''javac' -classpath - "
     + """/sys$library/j2vms$vs.jar:./bin"" -d ""./bin"""
$
$ set verify
$ $ ! Database Interface
$ jc Database.java
$ jc DATABASEDEF.java
$
$ ! Supporting classes
$ jc UpperCaseField.java
$
$ ! Application
$ jc EntryPanel.java
$ jc EventPanel.java
$ jc JPhone.java
$
$ set noverify
$
$ jphone == "''java' -classpath " -
          + """/sys$library/j2vms$vs.jar:./bin"" com.kednos.jphone.JPhone"
$
$ write sys$output "Type: ""jphone"" to run"
$bail_out:
$ set noverify
$ exitt 1
$ @BUILD_JPHONE.COM

$ javac -classpath "/sys$library/j2vms$vs.jar" put.java
$ java -classpath "/sys$library/j2vms$vs.jar:./" put

Assuming the correct J2VMS and Java setup has been performed, the following commands should build and execute the example program.

$ javac -classpath "/sys$library/j2vms$vs.jar" get.java
$ java -classpath "/sys$library/j2vms$vs.jar:./" get

This program is an example that demonstrates the use of OpenVMS disk drivers using RMS and QIO services. It is based on the C module of the same name and produces identical results. The C version can be found in SYS$EXAMPLES or can be downloaded here. The following comments are from the module header:

  DISK_DRIVER -- Programming example to demonstrate use of
  OpenVMS disk drivers using RMS and QIO services.  The module
  first uses RMS $CREATE to create a file called MYDATAFIL.DAT in
  the default directory and then writes one hundred 512-byte (1 disk
  block) records, each of which contains the record number
  repeated 512 times, using RMS $PUT.  It then uses QIO services
  to access, randomly read and write, and close the file, swapping the
  contents of each pair of records.  If any errors are detected,
  the program exits with the error status associated with the
  error.

Assuming the correct J2VMS and Java setup has been performed, the following commands should build and execute the example program.

$ javac -classpath "/sys$library/j2vms$vs.jar" disk_driver.java
$ java -classpath "/sys$library/j2vms$vs.jar:./" disk_driver

Assuming the correct J2VMS and Java setup has been performed, the following commands should build and execute the example program.

$ javac -classpath "/sys$library/j2vms$vs.jar" lock.java
$ java -classpath "/sys$library/j2vms$vs.jar:./" lock

Assuming the correct J2VMS and Java setup has been performed, the following commands should build and execute the example program.

$ javac -classpath "/sys$library/j2vms$vs.jar" get2.java
$ java -classpath "/sys$library/j2vms$vs.jar:./" get2