Examples

REXX Examples

These examples run inside the CMS machine interactive console. Launch a machine and try them at the prompt:

mkdir -p /tmp/cms/a
cargo run -p cms-machine -- --userid ALICE --disk /tmp/cms

The example EXECs are in crates/cms-machine/execs/ and are loaded automatically from the A-disk.

GREET — Send an SMSG

Send a greeting message to another machine. Demonstrates SMSG from REXX with return code checking.

/* GREET EXEC — at the CMS prompt: GREET BOB */
parse arg userid .
if userid = '' then do
    say 'Usage: GREET userid'
    exit 24
end

say 'Sending greeting to' userid '...'
'SMSG' userid 'Hello from CMS!'
if rc = 0 then
    say 'Greeting sent successfully.'
else
    say 'Could not reach' userid '— RC='rc
exit rc

Ready; T=0.01/0.01
GREET BOB
Sending greeting to BOB ...
Greeting sent successfully.

COUNTER — Persistent State with GLOBALV

A counter that survives across EXEC invocations. Demonstrates GLOBALV groups for persistent state management.

/* COUNTER EXEC */
parse upper arg action .
'GLOBALV SELECT COUNTER'

if action = 'RESET' then do
    'GLOBALV SET COUNT 0'
    say 'Counter reset to 0.'
    exit 0
end

'GLOBALV GET COUNT'
if rc \= 0 then count = 0

count = count + 1
'GLOBALV SET COUNT' count
say 'Counter:' count
exit 0

Ready; T=0.01/0.01
COUNTER
Counter: 1
Ready; T=0.01/0.01
COUNTER
Counter: 2
Ready; T=0.01/0.01
COUNTER RESET
Counter reset to 0.

UPPER — Data Transformation with PIPE

Uses CMS Pipelines to transform text. Demonstrates the PIPE command from REXX.

/* UPPER EXEC */
parse arg text
if text = '' then do
    say 'Usage: UPPER some text here'
    exit 24
end
'PIPE literal' text '| console'

Ready; T=0.01/0.01
UPPER hello world
hello world

SPOOLQ — Spool Queue Status

Queries the virtual reader, printer, and punch queues. Demonstrates spool commands from REXX.

/* SPOOLQ EXEC */
parse upper arg device .
if device = '' then do
    say '--- Reader ---'
    'QUERY RDR'
    say ''
    say '--- Printer ---'
    'QUERY PRT'
    say ''
    say '--- Punch ---'
    'QUERY PUN'
end

Ready; T=0.01/0.01
SPOOLQ
--- Reader ---
No spool files.

--- Printer ---
No spool files.

--- Punch ---
No spool files.

DISPATCH — Multi-EXEC Composition

Composes COUNTER, GREET, and SPOOLQ into a single workflow. Demonstrates REXX EXECs calling other EXECs.

/* DISPATCH EXEC */
parse arg userid .

say '=== Running COUNTER three times ==='
do i = 1 to 3
    'EXEC COUNTER'
end

if userid \= '' then do
    say ''
    say '=== Sending greeting to' userid '==='
    'EXEC GREET' userid
end

say ''
say '=== Spool status ==='
'EXEC SPOOLQ'

say ''
say '=== Done ==='
exit 0

Ready; T=0.01/0.01
DISPATCH BOB
=== Running COUNTER three times ===
Counter: 1
Counter: 2
Counter: 3

=== Sending greeting to BOB ===
Sending greeting to BOB ...
Greeting sent successfully.

=== Spool status ===
--- Reader ---
No spool files.
...

=== Done ===

Rust Library Examples

These examples demonstrate the vm-iucv library API for embedding the actor framework in your own Rust programs. They require Rust and are run with cargo:

hello_smsg

Basic machine lifecycle: IPL two machines, send an SMSG, shut down.

cargo run -p vm-iucv --example hello_smsg --features examples

echo_server

Request/reply pattern: an ECHO machine replies to every SMSG with the same text. Uses ctx.try_send_smsg() inside a handler callback.

cargo run -p vm-iucv --example echo_server --features examples

multi_machine_pipeline

Multi-machine coordination: PRODUCER → TRANSFORM → SINK chain where each machine forwards modified messages via SMSG.

cargo run -p vm-iucv --example multi_machine_pipeline --features examples

connection_gating

IUCV connection security: a SECURE machine accepts connections only from an allowlist. Demonstrates on_connection_pending callback.

cargo run -p vm-iucv --example connection_gating --features examples

iucv_chat

Full IUCV path lifecycle: CONNECT → ESTABLISHED → SEND → SEVER between two machines.

cargo run -p vm-iucv --example iucv_chat --features examples