The example shows how some nodes could be executed several times in a cycle.
For example you want to send an email but something went wrong and the server is not available and you want to retry the operation.
mkdir ~/pvm-cycle
cd ~/pvm-cycle
composer req formapro/pvm:0.4.x-dev makasim/values:0.5.x-dev
# create such file with the code below
php cycle.php
cycle.php
failed to send email
failed to send email
failed to send email
email is sent
cycle.php
<?php
use Formapro\Pvm\DefaultBehaviorRegistry;
use Formapro\Pvm\ProcessEngine;
use Formapro\Pvm\Token;
use Formapro\Pvm\ProcessBuilder;
require_once __DIR__.'/vendor/autoload.php';
$process = (new ProcessBuilder())
->createNode('send_email', 'send_email')->end()
->createNode('email_sent', 'email_sent')->end()
->createTransition('send_email', 'send_email', 'retry')->end()
->createTransition('send_email', 'email_sent')->end()
->createStartTransition('send_email')->end()
->getProcess()
;
$engine = new ProcessEngine(new DefaultBehaviorRegistry([
'email_sent' => function(Token $token) {
echo 'email is sent'.PHP_EOL;
},
'send_email' => function(Token $token) {
$counter = $token->getValue('counter', 0);
$counter++;
$token->setValue('counter', $counter);
try {
if ($counter < $token->getValue('maxRetries')) {
throw new \LogicException('Mail server is down');
}
} catch (\Throwable $e) {
echo 'failed to send email'.PHP_EOL;
return 'retry';
}
},
]));
$token = $engine->createTokenFor($process->getStartTransition());
$token->setValue('maxRetries', rand(2, 4));
$engine->proceed($token);
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/Process.json",
"id": "8af6d1da-b7c0-482e-b567-cd7db708bd41",
"nodes": {
"send_email": {
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/Node.json",
"id": "send_email",
"behavior": "send_email"
},
"email_sent": {
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/Node.json",
"id": "email_sent",
"behavior": "email_sent"
}
},
"transitions": {
"37ff0e80-e9db-49c0-8cb1-4e85a2cb8ab8": {
"id": "37ff0e80-e9db-49c0-8cb1-4e85a2cb8ab8",
"weight": 1,
"async": false,
"active": true,
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/Transition.json",
"name": "retry",
"from": "send_email",
"to": "send_email"
},
"e8913f9f-2fa0-4c0e-a14c-fbb5e9c60117": {
"id": "e8913f9f-2fa0-4c0e-a14c-fbb5e9c60117",
"weight": 1,
"async": false,
"active": true,
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/Transition.json",
"from": "send_email",
"to": "email_sent"
},
"05252b47-a235-4519-80a3-8dd5ec92d335": {
"id": "05252b47-a235-4519-80a3-8dd5ec92d335",
"weight": 1,
"async": false,
"active": true,
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/Transition.json",
"to": "send_email"
}
},
"outTransitions": {
"send_email": [
"37ff0e80-e9db-49c0-8cb1-4e85a2cb8ab8",
"e8913f9f-2fa0-4c0e-a14c-fbb5e9c60117"
]
},
"inTransitions": {
"send_email": [
"37ff0e80-e9db-49c0-8cb1-4e85a2cb8ab8",
"05252b47-a235-4519-80a3-8dd5ec92d335"
],
"email_sent": [
"e8913f9f-2fa0-4c0e-a14c-fbb5e9c60117"
]
},
"tokens": {
"4f6329f7-82d1-45b2-b465-a347987c36d3": {
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/Token.json",
"id": "4f6329f7-82d1-45b2-b465-a347987c36d3",
"transitions": [
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "4f678ae1-3d73-4468-b9da-09847d0f565c",
"transitionId": "05252b47-a235-4519-80a3-8dd5ec92d335",
"weight": 1,
"state": "opened",
"time": 15857737719667
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "faba04ba-e308-4c52-b885-0f168df6c952",
"transitionId": "05252b47-a235-4519-80a3-8dd5ec92d335",
"weight": 1,
"state": "passed",
"time": 15857737719675
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "d305a2cd-3573-464e-9b57-2ef1dce68909",
"transitionId": "37ff0e80-e9db-49c0-8cb1-4e85a2cb8ab8",
"weight": 1,
"state": "opened",
"time": 15857737719680
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "d14974ec-3b2a-4316-88d0-558482765b2b",
"transitionId": "37ff0e80-e9db-49c0-8cb1-4e85a2cb8ab8",
"weight": 1,
"state": "passed",
"time": 15857737719688
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "0e1ebd3e-3657-4541-9783-759a9375bbdb",
"transitionId": "37ff0e80-e9db-49c0-8cb1-4e85a2cb8ab8",
"weight": 1,
"state": "opened",
"time": 15857737719693
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "d25453d4-55db-4ea1-bf2b-3720f9c113dc",
"transitionId": "37ff0e80-e9db-49c0-8cb1-4e85a2cb8ab8",
"weight": 1,
"state": "passed",
"time": 15857737719700
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "18b2d811-fb61-47a9-9ae9-fbdb0a8d511c",
"transitionId": "37ff0e80-e9db-49c0-8cb1-4e85a2cb8ab8",
"weight": 1,
"state": "opened",
"time": 15857737719705
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "5ff67052-c264-420f-af5b-658556de4fbc",
"transitionId": "37ff0e80-e9db-49c0-8cb1-4e85a2cb8ab8",
"weight": 1,
"state": "passed",
"time": 15857737719711
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "6d71dcb3-5637-4866-b8d8-d2ae45e2fb0b",
"transitionId": "e8913f9f-2fa0-4c0e-a14c-fbb5e9c60117",
"weight": 1,
"state": "opened",
"time": 15857737719716
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "5d0e6a72-b4af-4f50-9518-e025310320dd",
"transitionId": "e8913f9f-2fa0-4c0e-a14c-fbb5e9c60117",
"weight": 1,
"state": "passed",
"time": 15857737719721
}
],
"maxRetries": 4,
"counter": 4
}
}
}