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Echo Endpoint

Echo requires a single HTTP endpoint (/api/echo or similar) to be exposed by your application. This endpoint is used to receive events from our Worker Engine.

You can view the Echo Endpoint as a webhook endpoint that Novu will call when it needs to retrieve contextual information for a given subscriber and notification.

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The serve function

We offer framework specific wrappers in form of an exported serve function that abstracts away:

  • Parsing the incoming request for GET, POST and PUT requests
  • HMAC Header Authentication
  • Framework Specific response and error handling

Currently, we offer serve functions for the following frameworks:

If we currently don’t support your framework, you can write a custom serve function that adheres to the following signature:

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Writing a custom serve function

Here is an example of a custom serve function for:

import { type Request, type Response } from 'express';
import { EchoRequestHandler, ServeHandlerOptions } from '@novu/echo';

export const serve = (options: ServeHandlerOptions): any => {
  const echoHandler = new EchoRequestHandler({
    frameworkName: 'express',
    ...options,
    handler: (
      incomingRequest: Request,
      response: Response,
    ) => ({
        method: () => incomingRequest.method,
        headers: (key) => {
            const header = incomingRequest.headers[key];
            return Array.isArray(header) ? header[0] : header;
        },
        queryString: (key) => {
                const qs = incomingRequest.query[key];
                return Array.isArray(qs) ? qs[0] : qs;
        },
        body: () => incomingRequest.body,
        url: () => new URL(incomingRequest.url, `https://${incomingRequest.headers.get("host") || ""}`),
        transformResponse: ({ body, headers, status }) => {
            Object.entries(headers).forEach(([headerName, headerValue]) => {
              response.setHeader(headerName, headerValue);
            });

            return response.status(status).send(body);
       },
    }),
  });

  return echoHandler.createHandler();
};

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