Event Sinks

Event sinks are the entry points that trigger flow executions. They define how external events (HTTP requests, scheduled tasks, bot messages) invoke your workflows.

Overview

Flow-Like supports multiple sink types, each with different characteristics:

Sink Type	Trigger Mechanism	Local Support	Remote Support
HTTP	REST API calls	✅ Polling	✅ Webhook
Telegram	Bot messages	✅ Long Polling	✅ Webhook
Discord	Bot interactions	✅ Gateway	✅ Interactions Webhook
Cron	Scheduled time	✅ Local scheduler	✅ Server scheduler
Webhook	Generic webhooks	❌	✅ Webhook

Local vs Remote Execution

Flow-Like can run workflows in two modes:

Local Mode (Desktop App)

When running the desktop application:

• HTTP: The app exposes a local server (default port 9657) that accepts requests
• Telegram: Uses long polling to fetch messages from Telegram’s API
• Discord: Connects via Discord Gateway (WebSocket) to receive events
• Cron: Uses local system scheduler to trigger at specified times

Advantages:

• No server infrastructure needed
• Direct access to local resources (files, applications)
• Lower latency for local operations
• Privacy - data stays on your machine

Limitations:

• Computer must be running
• Not accessible from the internet (without tunneling)
• Limited scalability

Remote Mode (Server/Cloud)

When deployed to a backend server:

• HTTP: Server exposes public endpoints that accept webhooks
• Telegram: Telegram sends webhooks directly to your server
• Discord: Discord sends interaction webhooks to your server
• Cron: Server-side scheduler triggers executions

Advantages:

• Always available (24/7)
• Publicly accessible
• Scalable infrastructure
• Handles high volume

Limitations:

• Requires server infrastructure
• Additional hosting costs
• Network latency for operations

Hub Configuration

The hub’s supported_sinks configuration determines which sinks are available:

{
  "supported_sinks": {
    "http": true,
    "telegram": true,
    "discord": true,
    "cron": true,
    "webhook": true
  }
}

When a sink type is disabled in the hub configuration, the corresponding event types will only be available for local execution.

Sink Architecture

┌─────────────────────────────────────────────────────────────────┐
│                      External Trigger                            │
│  (HTTP Request / Telegram Message / Discord Interaction / Cron)  │
└────────────────────────────────┬────────────────────────────────┘
                                 │
                    ┌────────────▼────────────┐
                    │      Sink Endpoint       │
                    │  /sink/trigger/{type}/   │
                    └────────────┬────────────┘
                                 │
                    ┌────────────▼────────────┐
                    │    Authentication &      │
                    │      Verification        │
                    │  (Tokens, Signatures)    │
                    └────────────┬────────────┘
                                 │
                    ┌────────────▼────────────┐
                    │    Event Lookup &        │
                    │    Sink Resolution       │
                    └────────────┬────────────┘
                                 │
                    ┌────────────▼────────────┐
                    │      Dispatcher          │
                    │  (async/streaming)       │
                    └────────────┬────────────┘
                                 │
                    ┌────────────▼────────────┐
                    │    Flow Execution        │
                    └─────────────────────────┘

Security

Each sink type has its own security mechanisms:

• HTTP: Optional Bearer token authentication
• Telegram: Secret token header verification + IP allowlist
• Discord: Ed25519 signature verification
• Cron: Internal scheduling (no external access)
• Webhook: Configurable authentication

See the individual sink documentation for detailed security configuration.