chat
A technology showcase.
Why?
This repo is designed as a showcase for how to build apps that scale.
We have built chat example apps a couple of times
before
and the response has been good,
this time our mission is to operate within a very tight set of constraints:
- No Servers
- Progressive Enhancement (Works when JavaScript is OFF!)
- Precisely Predictable (Linear) Performance
What?
Chat. Probably the most scalable implementation you will see.
How?
Lambda
S3
We use S3 to render our initial page and host all our static content. https://aws.amazon.com/s3/
API Gateway
API Gateway routes the requests we make from the front-end through to the Lambda function that will process it. https://aws.amazon.com/api-gateway/
Lambda
https://aws.amazon.com/lambda/
DynamoDB
https://aws.amazon.com/dynamodb/
Cognito
IOT
WebRTC?
Over 50% of browsers (Firefox & Chrome) which means we can cut-out paying for IOT messages for the people who are using good browsers.
http://caniuse.com/#feat=rtcpeerconnection
This also means when we use Electron
How much ($£€) ?
How much does all of this cost...?
Let's break down the cost in the order of the Tech Stack.
S3
https://aws.amazon.com/s3/pricing/
API Gateway
https://aws.amazon.com/api-gateway/pricing/
What is a read/write capacity unit? http://aws.amazon.com/dynamodb/faqs/#What_is_a_readwrite_capacity_unit
Lambda
https://aws.amazon.com/lambda/pricing/
DynamoDB
https://aws.amazon.com/dynamodb/pricing/
Cognito
Amazon Cognito costs $0.15 for each 10,000 sync operations and $0.15 per GB of sync store per month.
https://aws.amazon.com/cognito/pricing/
IOT
$5 per million messages.
A message is a 512-byte block of data processed by AWS IoT – either published to or delivered by the Service. For example, a 900-byte payload is billed as two messages.
https://aws.amazon.com/iot/pricing/
Background Reading
Learning by Doing
- Access HTTP Headers: http://stackoverflow.com/questions/31372167/how-to-access-http-headers-for-request-to-aws-api-gateway-using-lambda
- Cookies on Lambda: http://stackoverflow.com/questions/31851860/access-http-request-headers-query-string-cookies-body-object-in-lambda-with
- Invoke Lambda by HTTP Request: http://stackoverflow.com/questions/29877220/invoke-a-aws-lambda-function-by-a-http-request
Discussion
We considered using S3 as our primary data store, but soon realized its not that "simple"... see: Why does S3 still not support Appending? https://news.ycombinator.com/item?id=10746969