Message Execution

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Execution Flow

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1. Campaign Trigger

1. The scheduler picks up the campaign
2. Validates configuration (sending list, audiences, creatives)
3. Begins audience evaluation

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2. Audience Evaluation

Audience A: 5,000 contacts
Audience B: 3,000 contacts
Overlap: 500 contacts
-----
Total unique: 7,500 contacts

• Exclude unsubscribed contacts
• Apply frequency capping (skip if sent recently)
• Verify phone numbers are valid

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3. Message Queuing

1. Select the message variant (based on percentage split or ML selection)
2. Resolve any placeholders (, personalization)
3. Create a QueuedTextMessage record
4. Set the sendtime

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Queue Priority

• FIFO (first-in, first-out)
• All messages from a campaign are queued together

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4. Message Delivery

1. Polls the queue for pending messages
2. Batches messages for efficiency
3. Sends via the configured SMS provider (Infobip, Twilio, etc.)
4. Handles rate limiting and retries

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Provider Integration

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Rate Limiting

• Respects per-second limits
• Backs off on errors
• Distributes load across time

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5. Status Tracking

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Delivery Webhooks

{
  "messageId": "msg_abc123",
  "status": "DELIVERED",
  "doneAt": "2024-01-15T10:30:00Z"
}

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Execution Timeline

• Audience size
• Queue depth
• Provider capacity

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Link Tracking

1. Original URLs are replaced with short links
2. MessageShortLink records are created
3. When clicked, the link service logs the click
4. User is redirected to the destination

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Failure Handling

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Retry Logic

• Provider timeout → retry in 30 seconds
• Rate limit hit → back off and retry
• 5xx error → retry with exponential backoff

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Permanent Failures

• Invalid phone number
• Blocked/blacklisted number
• Carrier rejection (spam)

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Alerts

• Delivery failures
• Spam complaints
• High error rates

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Monitoring Execution

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Dashboard

1. Go to Schedules
2. Click on an active campaign
3. See live stats: sent, delivered, failed

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Metrics

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Troubleshooting

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Architecture

┌─────────────┐     ┌─────────────┐     ┌─────────────┐
│  Scheduler  │────▶│   Queue     │────▶│  Executor   │
│ (triggers)  │     │  (MongoDB)  │     │  (worker)   │
└─────────────┘     └─────────────┘     └─────────────┘
                                               │
                                               ▼
                                        ┌─────────────┐
                                        │   Provider  │
                                        │ (Infobip)   │
                                        └─────────────┘

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Next Steps