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
`switch...case...default`	Execute different statements based on the value of an expression
`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

Command/Function Execution

**Table 1-4**
`call`	Executes an installed function or JPL procedure
`runreport`	Run a report

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 Panther's database drivers.

JetNet/Oracle 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
**Oracle 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 Panther variables
`wait`	Waits for service calls to return before processing resumes

Event Broker Processing

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