Sending messages from Symfony with the Sent PHP SDK

This guide shows you how to wire Sent messaging into an existing Symfony app: install the PHP SDK, register a shared client service, send a template message from a controller, receive delivery webhooks, and verify the whole loop in sandbox mode.

Prerequisites

This guide assumes a working Symfony 7 app and familiarity with controllers, services, and attributes. You also need:

A Sent API key from the API Keys page in your Sent Dashboard
A public HTTPS URL for webhook delivery. For local work, open a tunnel as described in the webhook local development guide

Install the SDK

Add the SDK to your existing project:

composer require sentdm/sent-dm-php

Register the client service

Add the credentials to .env.local; the webhook secret arrives in step 4:

# .env.local
SENT_DM_API_KEY=your_api_key_here
SENT_DM_WEBHOOK_SECRET=whsec_your_signing_secret

# config/services.yaml (additions)
services:
    SentDm\Client:
        arguments:
            $apiKey: '%env(SENT_DM_API_KEY)%'

Send a template message from a controller

Define a validated payload DTO; the pass-through sandbox flag lets callers exercise the endpoint without delivering anything:

// src/Dto/SendMessageDto.php
namespace App\Dto;

use Symfony\Component\Validator\Constraints as Assert;

class SendMessageDto
{
    #[Assert\NotBlank]
    #[Assert\Regex(pattern: '/^\+[1-9]\d{1,14}$/', message: 'Phone number must be in E.164 format')]
    public string $phoneNumber;

    #[Assert\NotBlank]
    #[Assert\Length(min: 1, max: 100)]
    public string $templateName;

    public ?array $parameters = null;

    #[Assert\All([new Assert\Choice(choices: ['sms', 'whatsapp', 'rcs'])])]
    public ?array $channels = null;

    public bool $sandbox = false;   // true = validate and simulate only
}

Add the controller that maps the payload and calls messages->send:

// src/Controller/MessagesController.php
namespace App\Controller;

use App\Dto\SendMessageDto;
use SentDm\Client;
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\JsonResponse;
use Symfony\Component\HttpKernel\Attribute\MapRequestPayload;
use Symfony\Component\Routing\Attribute\Route;

#[Route('/api/messages')]
class MessagesController extends AbstractController
{
    public function __construct(private readonly Client $client) {}

    #[Route('/send', methods: ['POST'])]
    public function send(#[MapRequestPayload] SendMessageDto $dto): JsonResponse
    {
        $response = $this->client->messages->send(
            to: [$dto->phoneNumber],
            template: [
                'name' => $dto->templateName,        // reference by name or id, never both
                'parameters' => $dto->parameters ?? [],
            ],
            channel: $dto->channels,                 // omit to let Sent pick per recipient
            sandbox: $dto->sandbox,
        );

        $recipient = $response->data->recipients[0];
        return $this->json([
            'message_id' => $recipient->messageID,
            'status' => $response->data->status,
        ], 202);
    }
}

Sent accepts sends asynchronously: the API responds with status QUEUED and one message_id per recipient-and-channel pair. Store the message_id. Delivery outcomes arrive on your webhook endpoint instead of in this response.

Receive delivery webhooks

Add a webhook controller that verifies the X-Webhook-Signature header against the raw request body before trusting any event. The scheme is HMAC-SHA256 over {X-Webhook-ID}.{X-Webhook-Timestamp}.{rawBody}, keyed with the base64-decoded secret after stripping its whsec_ prefix. Refer to webhook signature verification for the full scheme. Every event arrives in the same envelope (field, event, timestamp, payload), so one handler routes all of them:

// src/Controller/WebhookController.php
namespace App\Controller;

use Psr\Log\LoggerInterface;
use Symfony\Component\DependencyInjection\Attribute\Autowire;
use Symfony\Component\HttpFoundation\JsonResponse;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\Routing\Attribute\Route;

class WebhookController
{
    public function __construct(
        #[Autowire(env: 'SENT_DM_WEBHOOK_SECRET')] private readonly ?string $webhookSecret,
        private readonly LoggerInterface $logger,
    ) {}

    #[Route('/webhooks/sent', methods: ['POST'])]
    public function handle(Request $request): JsonResponse
    {
        if (empty($this->webhookSecret)) {
            // Fail closed: never accept webhooks without a configured secret
            return new JsonResponse(['error' => 'Webhook not configured'], 500);
        }

        $signature = $request->headers->get('X-Webhook-Signature');
        if (!$signature) {
            return new JsonResponse(['error' => 'Missing signature'], 401);
        }

        $payload   = $request->getContent();
        $webhookId = $request->headers->get('X-Webhook-ID', '');
        $timestamp = $request->headers->get('X-Webhook-Timestamp', '');

        // Strip the "whsec_" prefix and base64-decode to get the raw HMAC key
        $keyBase64 = str_starts_with($this->webhookSecret, 'whsec_') ? substr($this->webhookSecret, 6) : $this->webhookSecret;
        $keyBytes  = base64_decode($keyBase64);
        // Signed content = "{webhookId}.{timestamp}.{rawBody}"; signature format = "v1,{base64(hmac)}"
        $signed    = "{$webhookId}.{$timestamp}.{$payload}";
        $expected  = 'v1,' . base64_encode(hash_hmac('sha256', $signed, $keyBytes, true));

        if (!hash_equals($expected, $signature)) {
            $this->logger->warning('Invalid webhook signature', ['ip' => $request->getClientIp()]);
            return new JsonResponse(['error' => 'Invalid signature'], 401);
        }

        $event   = json_decode($payload, true) ?? [];
        $subType = $event['event'] ?? null;      // omitted for template events
        $data    = $event['payload'] ?? [];

        if (($event['field'] ?? null) === 'message') {
            match ($subType) {
                'message.delivered' => $this->logger->info('Message delivered',
                    ['message_id' => $data['message_id'] ?? null]),
                'message.failed' => $this->logger->error('Message failed',
                    ['message_id' => $data['message_id'] ?? null, 'status' => $data['message_status'] ?? null]),
                'message.received' => $this->logger->info('Inbound message',
                    ['from' => $data['inbound_number'] ?? null, 'text' => $data['text'] ?? null]),
                default => $this->logger->info('Message status updated',
                    ['message_id' => $data['message_id'] ?? null, 'status' => $data['message_status'] ?? null]),
            };
        }

        return new JsonResponse(['received' => true]);
    }
}

Keep this route outside your firewall's authenticated area (config/packages/security.yaml), because Sent authenticates with the signature. Then tell Sent where to deliver events. If you prefer a UI, use the webhooks getting started guide; otherwise register over the API:

curl -X POST https://api.sent.dm/v3/webhooks \
  -H "x-api-key: $SENT_DM_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "display_name": "Symfony integration",
    "endpoint_url": "https://your-domain.example/webhooks/sent",
    "event_types": ["message"]
  }'

Copy two values from the response: the webhook id (used to test delivery in the next step) and signing_secret. Put the secret in SENT_DM_WEBHOOK_SECRET. The message event type covers every message event; the webhook event types reference lists all payload fields.

Verify the integration

Start the app with your credentials loaded:

symfony server:start

Send a sandbox message through your new endpoint. Full validation runs, but nothing is delivered and no credits are consumed:

curl -X POST http://localhost:8000/api/messages/send \
  -H "Content-Type: application/json" \
  -d '{"phoneNumber": "+14155551234", "templateName": "welcome",
       "parameters": {"name": "Ada"}, "sandbox": true}'

The response should contain a message_id and "status": "QUEUED". A 422 here means the request shape is wrong: sandbox requests return real validation errors.

Now confirm webhook delivery end to end. Ask Sent to deliver a signed test event, replacing the ID with the webhook id you copied:

curl -X POST https://api.sent.dm/v3/webhooks/YOUR_WEBHOOK_ID/test \
  -H "x-api-key: $SENT_DM_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"event_type": "message.delivered"}'

Your application log should show a Message delivered line, and the endpoint should have answered 200 {"received": true}. Test events travel the same signed delivery pipeline as real events, so a 401 in your log means the signing secret or verification code is wrong. Sent attempts a test event exactly once, so re-run the command after each fix.

Adapt this to your app

Sent retries non-2xx webhook responses with backoff, so make processing idempotent. Keying status updates on payload.message_id achieves this naturally; see handling webhook retries.
If you send outside the request cycle, dispatch a Messenger command and let a worker call the API. The appendix below has the pattern.
If you rate-limit send endpoints, use Symfony's rate_limiter component. The appendix has the configuration.
To send free-form text instead of a template, pass text instead of template, since each send carries exactly one of the two.

Appendix: production scaffolding

The numbered steps stay on the core messaging tasks. The blocks below are optional scaffolding for a production Symfony stack. Adapt them to your own conventions rather than adopting them wholesale.

Next steps

Review the webhook event types reference for every payload field
Work through the webhook production checklist before going live
Explore the PHP SDK reference for retries, timeouts, and error types
Read the SDK best practices guide for production deployments

Async sends with Symfony Messenger

Rate limiting send endpoints

Testing the webhook signature

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