Call, trigger, or nest workflows with HTTP endpoints in logic apps

• 03/31/2017
• 8 minutes to read
• Contributors
  • 
  • 
  • 
  • 
  • 
  • all

You can natively expose synchronous HTTP endpoints as triggers on logic apps so that you can trigger or call your logic apps through a URL. You can also nest workflows in your logic apps by using a pattern of callable endpoints.

To create HTTP endpoints, you can add these triggers so that your logic apps can receive incoming requests:

• Request

• API Connection Webhook

• HTTP Webhook

  Note

  Although these examples use the Request trigger, you can use any of the listed HTTP triggers, and all principles identically apply to the other trigger types.

Set up an HTTP endpoint for your logic app

To create an HTTP endpoint, add a trigger that can receive incoming requests.

1. Sign in to the Azure portal. Go to your logic app, and open Logic App Designer.

2. Add a trigger that lets your logic app receive incoming requests. For example, add the Request trigger to your logic app.

3. Under Request Body JSON Schema, you can optionally enter a JSON schema for the payload (data) that you expect the trigger to receive.

   The designer uses this schema for generating tokens that your logic app can use to consume, parse, and pass data from the trigger through your workflow. More about tokens generated from JSON schemas.

   For this example, enter the schema shown in the designer:

   {
     "type": "object",
     "properties": {
       "address": {
         "type": "string"
       }
     },
     "required": [
       "address"
     ]
   }
   

   

   Tip

   You can generate a schema for a sample JSON payload from a tool like jsonschema.net, or in the Request trigger by choosing Use sample payload to generate schema. Enter your sample payload, and choose Done.

   For example, this sample payload:

   {
      "address": "21 2nd Street, New York, New York"
   }
   

   generates this schema:

   {
      "type": "object",
      "properties": {
         "address": {
            "type": "string" 
         }
      }
   }
   

4. Save your logic app. Under HTTP POST to this URL, you should now find a generated callback URL, like this example:

   

   This URL contains a Shared Access Signature (SAS) key in the query parameters that are used for authentication. You can also get the HTTP endpoint URL from your logic app overview in the Azure portal. Under Trigger History, select your trigger:

   

   Or you can get the URL by making this call:

   POST https://management.azure.com/{logic-app-resourceID}/triggers/{myendpointtrigger}/listCallbackURL?api-version=2016-06-01
   

Change the HTTP method for your trigger

By default, the Request trigger expects an HTTP POST request, but you can use a different HTTP method.

1. On your Request trigger, choose Show advanced options.

2. Open the Method list. For this example, select GET so that you can test your HTTP endpoint's URL later.

   Note

   You can select any other HTTP method, or specify a custom method for your own logic app.

   

Accept parameters through your HTTP endpoint URL

When you want your HTTP endpoint URL to accept parameters, customize your trigger's relative path.

1. On your Request trigger, choose Show advanced options.

2. Under Method, specify the HTTP method that you want your request to use. For this example, select the GET method, if you haven't already, so that you can test your HTTP endpoint's URL.

   Note

   When you specify a relative path for your trigger, you must also explicitly specify an HTTP method for your trigger.

3. Under Relative path, specify the relative path for the parameter that your URL should accept, for example, customers/{customerID}.

   

4. To use the parameter, add a Response action to your logic app. (Under your trigger, choose New step > Add an action > Response)

5. In your response's Body, include the token for the parameter that you specified in your trigger's relative path.

   For example, to return Hello {customerID}, update your response's Body with Hello {customerID token}. The dynamic content list should appear and show the customerID token for you to select.

   

   Your Body should look like this example:

   

6. Save your logic app.

   Your HTTP endpoint URL now includes the relative path, for example:

   https://prod-00.southcentralus.logic.azure.com/workflows/f90cb66c52ea4e9cabe0abf4e197deff/triggers/manual/paths/invoke/customers/{customerID}...

7. To test your HTTP endpoint, copy and paste the updated URL into another browser window, but replace {customerID} with 123456, and press Enter.

   Your browser should show this text:

   Hello 123456

Tokens generated from JSON schemas for your logic app

When you provide a JSON schema in your Request trigger, the Logic App Designer generates tokens for properties in that schema. You can then use those tokens for passing data through your logic app workflow.

For this example, if you add the title and name properties to your JSON schema, their tokens are now available to use in later workflow steps.

Here is the complete JSON schema:

{
   "type": "object",
   "properties": {
      "address": {
         "type": "string"
      },
      "title": {
         "type": "string"
      },
      "name": {
         "type": "string"
      }
   },
   "required": [
      "address",
      "title",
      "name"
   ]
}

Create nested workflows for logic apps

You can nest workflows in your logic app by adding other logic apps that can receive requests. To include these logic apps, add the Azure Logic Apps - Choose a Logic Apps workflow action to your trigger. You can then select from eligible logic apps.

Call or trigger logic apps through HTTP endpoints

After you create your HTTP endpoint, you can trigger your logic app through a POST method to the full URL. Logic apps have built-in support for direct-access endpoints.

Reference content from an incoming request

If the content's type is application/json, you can reference properties from the incoming request. Otherwise, content is treated as a single binary unit that you can pass to other APIs. To reference this content inside the workflow, you must convert that content. For example, if you pass application/xml content, you can use @xpath() for an XPath extraction, or @json() for converting XML to JSON. Learn about working with content types.

To get the output from an incoming request, you can use the @triggerOutputs() function. The output might look like this example:

{
    "headers": {
        "content-type" : "application/json"
    },
    "body": {
        "myProperty" : "property value"
    }
}

To access the body property specifically, you can use the @triggerBody() shortcut.

Respond to requests

You might want to respond to certain requests that start a logic app by returning content to the caller. To construct the status code, header, and body for your response, you can use the Response action. This action can appear anywhere in your logic app, not just at the end of your workflow.

Construct the response

You can include more than one header and any type of content in the response body. In the example response, the header specifies that the response has content type application/json. and the body contains title and name, based on the JSON schema updated previously for the Request trigger.

Responses have these properties:

Here's what the JSON schema looks like now for the Response action:

"Response": {
   "inputs": {
      "body": {
         "title": "@{triggerBody()?['title']}",
         "name": "@{triggerBody()?['name']}"
      },
      "headers": {
           "content-type": "application/json"
      },
      "statusCode": 200
   },
   "runAfter": {},
   "type": "Response"
}

Q & A

Q: What about URL security?

A: Azure securely generates logic app callback URLs using a Shared Access Signature (SAS). This signature passes through as a query parameter and must be validated before your logic app can fire. Azure generates the signature using a unique combination of a secret key per logic app, the trigger name, and the operation that's performed. So unless someone has access to the secret logic app key, they cannot generate a valid signature.

Q: Can I configure HTTP endpoints further?

A: Yes, HTTP endpoints support more advanced configuration through API Management. This service also offers the capability for you to consistently manage all your APIs, including logic apps, set up custom domain names, use more authentication methods, and more, for example:

• Change the request method
• Change the URL segments of the request
• Set up your API Management domains in the Azure portal
• Set up policy to check for Basic authentication

Q: What changed when the schema migrated from the December 1, 2014 preview?

A: Here's a summary about these changes:

Get help

To ask questions, answer questions, and learn what other Azure Logic Apps users are doing, visit the Azure Logic Apps forum.

To help improve Azure Logic Apps and connectors, vote on or submit ideas at the Azure Logic Apps user feedback site.

Next steps

• Author logic app definitions
• Handle errors and exceptions