Logic Apps Triggers — HTTP, Recurrence, and Service Bus

What You'll Learn

How triggers work in Logic Apps, the difference between push and polling triggers, and how to configure the three most common trigger types.

Prerequisites

• Completed: Create Your First Logic App

Understanding Triggers

Every Logic App workflow starts with exactly one trigger. Triggers determine when and how your workflow runs.

┌─────────────────────────────────────────────────────────┐
│                    TRIGGER TYPES                         │
├─────────────────────────────────────────────────────────┤
│                                                         │
│  PUSH Triggers          │  POLLING Triggers             │
│  (Event fires workflow) │  (Workflow checks for events) │
│                         │                               │
│  • HTTP Request         │  • Recurrence (timer)         │
│  • Event Grid           │  • Service Bus (peek-lock)    │
│  • Service Bus (push)   │  • SQL (check for new rows)   │
│  • Webhook              │  • File System (new files)    │
│                         │                               │
└─────────────────────────────────────────────────────────┘

Trigger 1: HTTP Request (Push)

The HTTP trigger fires immediately when a request arrives — zero delay.

Create the workflow

1. In your Logic App → Workflows → + Add
2. Name: http-trigger-demo, State: Stateful
3. Open Designer → Add trigger → When a HTTP request is received

Configure with JSON Schema

To validate incoming requests, add a JSON schema:

{
  "type": "object",
  "properties": {
    "orderId": { "type": "string" },
    "amount": { "type": "number" },
    "customer": { "type": "string" }
  },
  "required": ["orderId", "amount"]
}

Key settings:

Trigger 2: Recurrence (Polling/Timer)

Runs your workflow on a schedule — like a cron job.

Create the workflow

1. Workflows → + Add → Name: scheduled-task, State: Stateful
2. Add trigger → Search Schedule → Select Recurrence

Configure the schedule

Advanced scheduling

For complex schedules (e.g., weekdays at 9 AM and 5 PM):

Interval: 1
Frequency: Week
On these days: Monday, Tuesday, Wednesday, Thursday, Friday
At these hours: 9, 17
At these minutes: 0

Trigger 3: Service Bus Queue (Polling)

Fires when a message arrives in a Service Bus queue.

Prerequisites

• Azure Service Bus namespace (Standard tier)
• A queue named orders

Create the connection

1. Workflows → + Add → Name: sb-processor, State: Stateful
2. Add trigger → Search Service Bus → Select When messages are available in a queue

3. Create a new connection:

4. Configure the trigger:

How polling works

The Service Bus trigger uses long polling — it checks the queue every few seconds. When messages arrive, the workflow fires. The trigger uses peek-lock — messages are locked during processing and completed on success.

Queue has messages? ──▶ YES ──▶ Lock message ──▶ Run workflow ──▶ Complete message
         │
         ▼
        NO ──▶ Wait (polling interval) ──▶ Check again

Trigger Comparison

Best Practices

1. Always add a JSON schema to HTTP triggers — enables IntelliSense in downstream actions
2. Use Managed Identity for Service Bus connections — no connection strings to manage
3. Set concurrency limits on triggers to prevent overwhelming downstream systems
4. Enable split-on for batch triggers to process each item as a separate run

Setting concurrency on a trigger:

In the trigger settings → Concurrency Control → Enable → Set degree of parallelism (e.g., 10)

What You Learned

Next Tutorial

→ Working with Connectors — SQL, Blob Storage, Outlook