How to subscribe AWS Lambda to Salesforce Platform Events - amazon-web-services

Question

We want to integrate Salesforce into out Micro Service Structure in AWS.
There is a article about this here
So we want to subscribe lambda to certain platform events in salesforce.
But i found no code examples for this. I gave it a try using node.js (without lambda). This works great:
var jsforce = require('jsforce');
var username = 'xxxxxxxx';
var password = 'xxxxxxxxxxx';
var conn = new jsforce.Connection({loginUrl : 'https://test.salesforce.com'});
conn.login(username, password, function(err, userInfo) {
if (err) { return console.error(err); }
console.error('Connected '+userInfo);
conn.streaming.topic("/event/Contact_Change__e").subscribe(function(message) {
console.dir(message);
});
});
But i am not sure if this is the right way to do it in lambda.

Answer 1

My understanding of Salesforce Platform Events is that they use CometD under the hood. CometD allows the HTTP client (your code) to subscribe to events published by the HTTP server.
This means your client code needs to be running and be in a state where it is subscribed and listening for server events for the duration of time that you expect to be receiving events. In most cases, this duration is indefinate i.e. your client code expects to wait forever in a subscribed state, ready to receive events.
This is at odds with AWS Lambda functions, which are expected to complete execution in a relatively short amount of time (max 15 minutes last time I checked).
I would suggest you need a long running process, such as a nodejs application running in Elastic Beanstalk, or in a container. The nodejs application can stay running indefinately, in a subscribed state. Each time it receives an event, it could call your AWS Lambda function in order to implement the required actions.