Serverless Bank Transfer

A rudimentary implementation of a bank transferring system, built using lambda functions and the serverless framework.

Requirements

Java == 8

Scala == 1.12

serverless framework

AWS credentials for an IAM user that can create lambdas and dynamodb tables.

Usage

cd serverless-bank-transfer
sbt assembly
serverless deploy

Then POST a request to the endpoint output by serverless, like:

curl -X POST https://REPLACE-ME.execute-api.us-east-1.amazonaws.com/dev/transfer/schedule --header 'content-type: application/json' --data @examples/no_scheduled_time_request.json

Test cases

TODO: Implement the following integration test cases:

Set-up for each of the following scenarios:

Balances table: Alice $100 Bob $50

Scenario 1 (insufficient balance for executed transfer)

#1: $100 Alice -> Bob now (success)

#2: $1 Alice -> Bob now (failure -- insufficient balance)

Scenario 2 (insufficient balance for scheduled transfer)

#1: $100 Alice -> Bob in 1 hour (success)

#2: $1 Alice -> Bob now (failure -- insufficient balance)

Scenario 3 (cancelling frees up available balance)

#1: $50 Bob -> Alice in 1 minute (success)

#2: $1 Bob -> Alice now (failure -- insufficient balance)

cancel transfer #1 (success)

#3: $50 Bob -> Alice now (success)

Scenario 4 (cancelling executed transaction fails)

#1: $1 Alice -> Bob now (success)

cancel transfer #1 (fails -- already executed)

Scenario 5 (same transfer ID re-sent)

#1: $1 Alice -> Bob now (success)

#2: Resend transfer #1 (failure -- transfer schedule request already processed)