Programming Guide

Chapter 1 . JPL Command Overview

Below is a summary of the JPL commands organized according to category. All JPL statements begin with one of these commands. For more information on each command, refer to Chapter 2, "JPL Command Reference."

Control Flow

**Table 1-1 JPL Control Flow Commands**
break	Exits a loop
for	Executes an indexed loop
if`...else if...else`	Conditionally executes statements
next	Skips to next iteration of loop
return	Exits a JPL procedure
while	Repeatedly executes statements while a condition is true

Procedure Structure

**Table 1-2**
parms	Declares parameters in an unnamed JPL procedure
proc	Begins a named procedure

Variable Declaration

**Table 1-3**
global	Declares global JPL variables
vars	Declares JPL variables in a procedure

Command/Function Execution

**Table 1-4**
call	Executes an installed function or JPL procedure

Module Access and Availability

**Table 1-5**
include	Includes contents of another module at current statement line
public	Reads a JPL module into memory and enables access to its named procedures
unload	Unloads modules loaded through the public command and releases their associated memory

Text Display

**Table 1-6**
flush	Flushes buffered output to the display
msg	Displays a message to the terminal

Data/Message Transfer

**Table 1-7**
receive	Receives data from a screen sent via send or from a remote client via `service_call`
send	Sends data to a buffer for retrieval by the receive command

Database Drivers

**Table 1-8**
dbms	Executes a command available in Prolifics's database drivers.

JetNet/BEA Tuxedo Processing

**Table 1-9**
jif_check	Determines if the JIF has changed
jif_read	Rereads the JIF
log	Logs a message to the machine event log

Connection

**Table 1-10**
client_exit	Closes the middleware session
client_init	Attaches a client to the middleware

Data/Message Transfer

**Table 1-11**
broadcast	Sends a message to a client
dequeue`**`	Releases a message from a reliable queue
enqueue`**`	Places a message on a reliable queue
notify	Sends an unsolicited message to a client
service_call	Initiates a service call from a client agent
service_forward	Forwards service request data to another service
service_return	Returns from a service request invocation
unload_data	Writes data received remotely via the middleware to target Prolifics variables
**BEA Tuxedo only

Service Request Processing

**Table 1-12**
advertise	Advertises services offered by a server to a client
service_call	Initiates a service call from a client agent
service_cancel	Cancels an outstanding service request
service_forward	Forwards service request data to another service
service_return	Returns from a service request invocation
unadvertise	Unadvertises services from a server
unload_data	Writes data received remotely via the middleware to target Prolifics variables
wait	Waits for service calls to return before processing re sumes

Event Broker Processing

**Table 1-13**
post`**`	Posts an event
subscribe`**`	Subscribes to an event
unsubscribe`**`	Unsubscribes from an event
**BEA Tuxedo only

Two-Phase Commit Transaction Processing

**Table 1-14**
xa_begin`**`	Starts a middleware transaction
xa_commit`**`	Commits a middleware transaction
xa_end`**`	Completes a middleware transaction
xa_rollback`**`	Aborts a middleware transaction
**BEA Tuxedo only

Component Processing (COM, EJB)

**Table 1-15**
log	Logs a message to server.log
raise_exception	Sends an error code back to the client
receive_args	Receives a method's parameters from the client
return_args	Returns the method's parameters to the client