http-wrapper.md

Microservice HTTP client wrappers

Motivation

Each microservice specifics should be abstracted from the current microservice code. A minimal number of classes should be aware of base URI or format of other microservices. Therefore, these specifics can be abstracted by a wrapper.

Description

MicroserviceHttpClientInterface is an HTTP client wrapper that adapt HTTP calls according to the targeted microservice configuration. This service could be retrieve by the id: api_platform_ms.http.client.{microservice_name}

If the targeted microservice could only be known at runtime, the HttpClient class allows you to request any microservice given as method argument.

Furthermore, if you need to replace the real HTTP client during runtime (which could be useful when using scoped clients), you can use the setWrappedHttpClient method of any ReplaceableHttpClientInterface.

Example

services:
    ProductService:
        arguments:
            $productHttpClient: 'api_platform_ms.http_client.microservice.product'

use Mtarld\ApiPlatformMsBundle\HttpClient\GenericHttpClient;
use Mtarld\ApiPlatformMsBundle\HttpClient\MicroserviceHttpClientInterface;
use Mtarld\ApiPlatformMsBundle\Microservice\MicroservicePool;

class ProductService
{
    private $httpClient;
    private $productHttpClient;
    private $microservices;

    public function __construct(
        GenericHttpClient $httpClient,
        MicroserviceHttpClientInterface $productHttpClient,
        MicroservicePool $microservices
    ) {
        $this->httpClient = $httpClient;
        $this->productHttpClient = $productHttpClient;
        $this->microservices = $microservices;
    }

    public function updateProductName(int $id, string $name): void
    {
        $productMicroservice = $this->microservices->get('product');
        $this->httpClient->request($productMicroservice, 'PUT', '/products/'.$id, ['name' => 'newName']);
    }

    public function createEmptyProduct(): void
    {
        $this->productHttpClient->request('POST', '/products', new ProductDto());
    }
}

Replacing the real HTTP client during runtime

use Mtarld\ApiPlatformMsBundle\HttpClient\GenericHttpClient;
use Mtarld\ApiPlatformMsBundle\HttpClient\MicroserviceHttpClientInterface;
use Mtarld\ApiPlatformMsBundle\Microservice\MicroservicePool;

class ProductService
{
    private $productHttpClient;
    private $superPrivilegedClient;

    public function __construct(
        MicroserviceHttpClientInterface $productHttpClient,
        HttpClientInterface $superPrivilegedClient
    ) {
        $this->productHttpClient = $productHttpClient;
        $this->superPrivilegedClient = $superPrivilegedClient;
    }

    public function createProduct(): void
    {
        $response = $this->productHttpClient->request('PUT', '/products/uuid', ['enabled' => true]);

        // retry with higher privileges
        if (403 === $response->getStatusCode()) {
            $this->productHttpClient->setWrappedHttpClient($this->superPrivilegedClient);
            $this->productHttpClient->request('PUT', '/products/uuid', ['enabled' => true]);
        }
    }
}