teewurst/pipeline

Recursive Pipeline Construct

v1.0 2020-01-14 19:20 UTC

This package is auto-updated.

Last update: 2020-10-14 21:13:36 UTC


README

With this lib, we are able to separate long executions into multiple tasks. A pipeline enables you to better fulfill single responsibility requirements. This results in better maintainability and testability.

How to

  • The Pipeline passes the Payload and its self into the task.

public function __invoke(PayloadInterface $payload, PipelineInterface $pipeline): PayloadInterface;

  • The first task calls the next task, calls the next task, calls the next task ...

$payloadAfterAllSteps = $pipeline->handle($payload);

  • Like in PSR-7 (the request object) you are now able to handle all information by adding and getting information from a payload object
$value = $genericPayload->getValue();
$value++;
$genericPayload->setValue($value);
Step-by-Step
  1. Create Task(s)
  2. Initialize Pipeline
  3. Fill Payload
  4. Execute Pipe
  5. Evaluate Pipe

Use Pipeline Service

You are able to simple create your pipelines from your DI (PSR-11 Container Service Manager required). It just takes two lines of code (+Config)

The PipelineService class allows you to pass tasks as service hashes.

// .. In your factory
$tasksFromEnvConfig = $config->getTasks() // somewhere in your config: [Task1::class, Task2::class, Task3::class];
$pipeline = (new PipelineService)->createPsr11($serviceManager, $tasksFromEnvConfig);

With teewurst/Pipeline you are able to create quite complex tasks in no time:

// Configuration of BiPRO Request (= German XML Request Standard)
$tasklist = [
    CheckServiceAvailabilityTask::class,
    [ // do Request
        ErrorHandlerTask::class, // catch execution of submission even on error
        [
            PrepareDataTask::class,
            ValidateDataTask::class,
            DoGetOfferRequestTask::class
        ],
        // .. some additional things like set quote, upload documents etc.
    ],
    [ // do something additionally
        LogResultLocalyTask::class,
        LogResultInDWTask::class,
    ]
];

Best Practices

  • Use RecursivePipeline to create "Sub Pipelines" => Dynamic Tasks
  • Because of the Structure every task has a "before handle next step" and "after handle next step"
  • Interrupt pipeline by throwing an exception or return $payload without handling the next step

Examples

Initialize Pipeline manually

Of course it would be better to use DI instead of new all the time

// Create Tasks in order of execution
$tasks = [
    new ExceptionTask(),
    new ErrorBagTask(),
    new OpenStreamTask(),
    new ReadValuesTask(),
    new ValidateValuesTask(),
    new RequireDocumentsTask(),
    new HandleImportTask(),
];

// Create Pipeline
$pipeline = new \teewurst\Pipeline\Pipeline($tasks);

// Create Payload
$payload = new ImportPayload();

// Setup Payload
$payload->setEnvironment($env); // <= here you also could use $pipeline->setOptions(...)
$payload->setConfig($config);

// Do the thing the pipeline is constructed for
$payload = $pipeline->handle($payload);
// Evaluate result
$payload->getMessage();
Simple Task which does something

Use the pipeline object to pass configuration and handle data between tasks

public function __invoke(PayloadInterface $payload, PipelineInterface $pipeline): PayloadInterface {
    // there is something, so we need to continue with our tasks
    if ($payload->getValue() > 0) {
        return $pipeline->handle($payload);
    }
    
    // we do not allow negative values => Completely interrupt process
    if ($payload->getValue() < 0) {
        throw new \Exception("Negative Values are not allowed here");
    }

    // Value is 0, let's pretend there is nothing more to do. => Interrupt from here and go back up the callstack
    return $payload;
}
Exception Handling Task

Handle (maybe only certain) exceptions within the pipe

public function __invoke(PayloadInterface $payload, PipelineInterface $pipeline): PayloadInterface {
    try {
        // handle next steps BEFORE doing something
        $payload = $pipeline->handle($payload);
    } catch (\Throwable $e) {
        $this->logger->logException($e, ['context' => $payload]);
    }
    return $payload;
}
Error Bag

Process multiple errors with error bags

public function __invoke(PayloadInterface $payload, PipelineInterface $pipeline): PayloadInterface {
    // Do something before handle next steps
    $payload->setErrorBag($this->errorBag);

    // Pipeline will add errors to error bag
    $payload = $pipeline->handle($payload);

    // "On the way back" and after handling, we check if something is inside the error bag
    if ($payload->getErrorBag()->hasErrors()) {
        $payload->setMessage($payload->getErrorBag()->toString());
    }
    
    return $payload;
}