A trigger is a configurable way of defining how an Azure Function is invoked. In our sample scenario, we would like our Function to be invoked when there is a message is available in the orders Service Bus queue:

[FunctionName("UpdateInventory")] 
        public async static void Run([ServiceBusTrigger("orders", Connection = "ShipAnyWhere_SERVICEBUS")]PurchaseOrder order 

The same configuration can also be done in the function.json file:

{ 
  "generatedBy": "Microsoft.NET.Sdk.Functions-1.0.24", 
  "configurationSource": "attributes", 
  "bindings": [ 
    { 
      "type": "serviceBusTrigger", 
      "connection": "ShipAnyWhere_SERVICEBUS", 
      "queueName": "orders", 
      "name": "order" 
    } 
  ], 
  "disabled": false, 
  "scriptFile": "../bin/ShipAnyWhere-AzureFunctions.dll", 
  "entryPoint": "ShipAnyWhere.UpdateInventory.Run" 
}