A great way of building data-driven apps using Felt is by triggering a workflow whenever something changes on a map, like someone drawing a polygon around an area of interest or updating the details on a pin.
Instead of polling by listing elements, comments or data layers on a fixed interval, a better alternative is to set up a webhook where Felt will send a notification any time a map is updated. This allows you to build integrations on top, such as sending a Slack message or performing calculations for the newly-drawn area.
Requirements
Two things are needed in order to make use of webhooks:
A Felt map which will serve as the basis for the webhook. Updates will be sent whenever something on this map changes.
A webhook URL where the updates will be sent in the form of POST requests.
Simply click on Generate new webhook, select a map to listen to changes and paste in a webhook URL where the updates will be sent to.
Using your new webhook
In order to use webhooks effectively, a receiving layer must be set up to trigger actions based on the updates sent by the Felt API. Here are some examples of how to set up a webhook using Felt and an external service.
Setting up an example webhook using Pipedream
Pipedream's RequestBin is an easy way to collect webhook requests and even run custom code as a result.
Create a free Pipedream account
On the left-hand sidebar, navigate to Sources, then click on New sourcein the top-right corner.
Select HTTP / Webhook, then New Requests (Payload Only), and give your newly-created source a name.
Copy the endpoint URL. It will look like https://XXX.m.pipedream.net
You may also add configure a script to run using the above input.
Setting up an example webhook using an AWS Lambda
Serverless functions like AWS Lambda or Google Cloud Functions are an excellent way of triggering code after a map update by setting them to run after a specific HTTP call.
In the AWS console, navigate to Lambda and click on Create function
Choose a name and runtime and, under Advanced Settings, make sure to check Enable function URL
Set Auth type to NONE and click on Create function
In the next screen, copy the Function URL. It should look like https://{LAMBDA_ID}.lambda-url.{REGION}.on.aws
Continue configuring your Lambda function as usual by editing the code that will run on map updates