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": "b3cb0d3c-1ae9-4150-8b8e-abf28677b902",
"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": {
"22800688-83b3-4db0-a6db-b4551916bb53": {
"id": "22800688-83b3-4db0-a6db-b4551916bb53",
"weight": 1,
"async": false,
"active": true,
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/Transition.json",
"name": "retry",
"from": "send_email",
"to": "send_email"
},
"13a844f5-dad4-47c6-9fcc-7e4927eac103": {
"id": "13a844f5-dad4-47c6-9fcc-7e4927eac103",
"weight": 1,
"async": false,
"active": true,
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/Transition.json",
"from": "send_email",
"to": "email_sent"
},
"6480b313-218d-4208-a4fc-6b1291835a49": {
"id": "6480b313-218d-4208-a4fc-6b1291835a49",
"weight": 1,
"async": false,
"active": true,
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/Transition.json",
"to": "send_email"
}
},
"outTransitions": {
"send_email": [
"22800688-83b3-4db0-a6db-b4551916bb53",
"13a844f5-dad4-47c6-9fcc-7e4927eac103"
]
},
"inTransitions": {
"send_email": [
"22800688-83b3-4db0-a6db-b4551916bb53",
"6480b313-218d-4208-a4fc-6b1291835a49"
],
"email_sent": [
"13a844f5-dad4-47c6-9fcc-7e4927eac103"
]
},
"tokens": {
"cee65290-a70c-476d-93e9-92ffdf2cd1d3": {
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/Token.json",
"id": "cee65290-a70c-476d-93e9-92ffdf2cd1d3",
"transitions": [
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "151fef79-4692-440f-a169-9c36bbc72ea3",
"transitionId": "6480b313-218d-4208-a4fc-6b1291835a49",
"weight": 1,
"state": "opened",
"time": 15508389442047
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "ecf085ab-9a39-4fee-8d33-4880ebf912d3",
"transitionId": "6480b313-218d-4208-a4fc-6b1291835a49",
"weight": 1,
"state": "passed",
"time": 15508389442053
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "bd666da7-0826-44f5-89c8-fdb89bb1a4de",
"transitionId": "22800688-83b3-4db0-a6db-b4551916bb53",
"weight": 1,
"state": "opened",
"time": 15508389442057
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "f0bbd4ba-cb2f-42e5-9a16-e16148a0769f",
"transitionId": "22800688-83b3-4db0-a6db-b4551916bb53",
"weight": 1,
"state": "passed",
"time": 15508389442063
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "e7f467e9-8627-4c37-9f3c-3929ff94d306",
"transitionId": "22800688-83b3-4db0-a6db-b4551916bb53",
"weight": 1,
"state": "opened",
"time": 15508389442067
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "afc185c9-2d1e-4b21-9285-c29a783407ac",
"transitionId": "22800688-83b3-4db0-a6db-b4551916bb53",
"weight": 1,
"state": "passed",
"time": 15508389442072
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "86d4a022-7c6f-41da-b39c-2d693423acc6",
"transitionId": "22800688-83b3-4db0-a6db-b4551916bb53",
"weight": 1,
"state": "opened",
"time": 15508389442075
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "cf73d546-67ec-4836-a4c1-2f591f1b6579",
"transitionId": "22800688-83b3-4db0-a6db-b4551916bb53",
"weight": 1,
"state": "passed",
"time": 15508389442080
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "fd6cad15-a09a-428d-9946-ffca9f6378f8",
"transitionId": "13a844f5-dad4-47c6-9fcc-7e4927eac103",
"weight": 1,
"state": "opened",
"time": 15508389442083
},
{
"schema": "http:\/\/pvm.forma-pro.com\/schemas\/TokenTransition.json",
"id": "4f756d24-ce51-4b6a-b12a-4f054460d696",
"transitionId": "13a844f5-dad4-47c6-9fcc-7e4927eac103",
"weight": 1,
"state": "passed",
"time": 15508389442089
}
],
"maxRetries": 4,
"counter": 4
}
}
}