Appsync Subscription Pattern

• 1. How Appsync Subscriptions work
• 2. How to trigger a subscription from a Lambda function
• 3. The lifecycle of websocket connections and subscriptions

AWS Demonstration of the same concept

• Video

Authorization Options

• Appsync Authorization Usecases

For the subecsription, we can write vtl to check if the logged in user matches the userId input or the PK of the item returned:

#if(! ${context.result})
    $utils.unauthorized()
#elseif(${context.identity.cognitoIdentityId} != ${context.arguments.userId})
    $utils.unauthorized()
#else
    $util.toJson($ctx.result)
#end