CODEWITHSUNDEEP
amazon-web-serviceswebsocketamazon-dynamodbserverless
Braydon
Braydon

Reputation: 251

Is it possible to subscribe to a WebSocket in a serverless fashion using AWS?

A website offers a websocket to get real-time data from. I'm trying to record data received from the websocket in a DynamoDB table for a data source for a serverless application. Their example of how to use the websocket is some Node.JS code using socket.io-client. Being JavaScript I thought to use an AWS Lambda function but they are not purposed to run constantly. Is there an AWS service to handle this sort of subscription? I don't want to make a small EC2 instance to run a tiny application just for this purpose.

Things I've looked at:

Any help would be greatly appreciated!

Upvotes: 24

Views: 15406

Answers (4)

Marco Silva
Marco Silva

Reputation: 574

If we are talking about to be the client, there's no solution/service, until now, on Amazon AWS that is serverless and stays alive just for the socket's living time (from connect to disconnect).

Unfortunately, I think we are left to work with instances for this kind of scenario.

Upvotes: 27

Tim Bijnen
Tim Bijnen

Reputation: 21

I have spent quite some time finding a solution for the same problem but there doesn't seem to be a way to keep a websocket client running except for using an ec2 server.

The maximum running time of a Lambda function did increase to 15 minutes which could make it worth invoking a function that keeps connecting a client for up to 15 minutes.

https://aws.amazon.com/about-aws/whats-new/2018/10/aws-lambda-supports-functions-that-can-run-up-to-15-minutes/

using the pricing calculator it looks like it would be $5 at minumum to always keep a client running

Unit conversions Number of requests: 4 per hour * (730 hours in a month) = 2920 per month Amount of memory allocated: 128 MB x 0.0009765625 GB in a MB = 0.125 GB Amount of ephemeral storage allocated: 512 MB x 0.0009765625 GB in a MB = 0.5 GB Pricing calculations 2,920 requests x 900,000 ms x 0.001 ms to sec conversion factor = 2,628,000.00 total compute (seconds) 0.125 GB x 2,628,000.00 seconds = 328,500.00 total compute (GB-s) 328,500.00 GB-s x 0.0000166667 USD = 5.48 USD (monthly compute charges) 2,920 requests x 0.0000002 USD = 0.00 USD (monthly request charges) 0.50 GB - 0.5 GB (no additional charge) = 0.00 GB billable ephemeral storage per function Lambda costs - Without Free Tier (monthly): 5.48 USD

Upvotes: 2

Ashan
Ashan

Reputation: 19738

API Gateway now supports WebSockets where you can handle the events in Lambda and also respond in a simplified way. For more information refer Announcing WebSocket APIs in Amazon API Gateway

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Also there are two other services in AWS you can use to achieve this,

  • AWS IOT Websockets:- The idea is clients will subscribe to IOT Topics and from Lambda it will push messages to client.

enter image description here

  • AWS AppSync (Newly Introduced):- Having a layer in between Lambda and DynamoDB which will provide WebSocket support.

Note: You might need to request for the preview of AppSync at the moment.

Upvotes: 0

Warren Parad
Warren Parad

Reputation: 4072

API Gateway directly supports websockets. So you can connect you connect APIGW websocket api to a lambda function and connect this to DynamoDB.

Detailed step by step guide for setting up websockets in APIGW is available.

An example setup might be:

# 1. Create API Gateway Websocket
# 2. Create integration
aws apigatewayv2 create-integration 
  --api-id APIGW_ID --integration-type AWS_PROXY 
  --integration-method POST
  --integration-uri arn:aws:apigateway:REGION:lambda:path/2015-03-31/functions/LAMBDA_ARN/invocations

Upvotes: -5

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