# WebhookListener

## Purpose

To allow a Webhook Listener to be created in Business Central so that the URI can be provide to a Source application that will call the Webhook when a particular event occurs.

## Use Case

We are creating an interface with a third-party Web application that allows us to register a URL as a Webhook listener for a specific event (such as a user's phone number being updated, an order being completed, a document being signed, etc.). We create a Webhook listener to process the incoming request and update our customer record in BC, or take whatever action is required.

## Implementation Details

A new Codeunit Subtype called WebhookListener. When selected this will change the method signature of the OnRun trigger to accept an HTTPRequest and return an HTTPResponse.

codeunit 50100 MyCodeunit
{

Subtype = WebhookListener;

trigger OnRun(HttpRequest: HttpRequestMessage) HttpResponse: HttpResponseMessage
begin

end;

}

We expose the Webhook API endpoint in a similar way to how we expose a Codeunit as a Web service. We create a record in the Web Service table with Object Type = Codeunit, Object ID = 50100, ServiceName = SomeEventListener and tick the Published field.

If the subtype for the Codeunit is WebhookListener, this will create an OData V4 URL:

https://businesscentral.dynamics.com/{{tenantId}}/{{environmentName}}/companies({{companyId}})/{{serviceName}}

Once the Web service is published, any requests made to that URL (no authentication is needed) will result in the OnRun trigger of a new instance of the Codeunit being run with the HttpRequest containing the contents of the received request. It is up to the code within the codeunit to handle the request and set an appropriate response.