meli-xmen-rest-API CHALLENGE

A serverless mutant DNA analyzer REST API written in JavaScript (nodeJs v8.10) for AWS cloud.

AWS Services used by the project

The following services are used either directly or indirectly by the project

• CloudFormation
• S3
• API Gateway
• Lambda
• DynamoDB
• CloudWatch

Running/testing the API

The API is currently published under the following endpoints:

POST - https://nqao9fdx9a.execute-api.us-east-1.amazonaws.com/dev/mutant

GET - https://nqao9fdx9a.execute-api.us-east-1.amazonaws.com/dev/stats

Sample input data

Valid input json messages for DNA analysis are provided inside /test/*.json There's also sample data from DynamoDB of a couple of test runs inside /sample_data/sample_meli-xmen-rest-api-dev.csv

Sample output

Mutant DNA - HTTP 200

{
    "id": "4606cd60-ca0c-11e9-880d-19af2e5d92fe",
    "dnaSequence": [
        "ATGCGA",
        "CAGTGC",
        "TTATGT",
        "AGAAGG",
        "CCCCTA",
        "TCACTG"
    ],
    "mutant": 1
}

Human DNA - HTTP 403

{
    "id": "501f2ef0-ca0c-11e9-880d-19af2e5d92fe",
    "dnaSequence": [
        "ATGCGA",
        "CAGTGC",
        "TTATTT",
        "AGACGG",
        "GCGTCA",
        "TCACTG"
    ],
    "mutant": 0
}

Stats - HTTP 200

{
    "count_mutant_dna": 13,
    "count_human_dna": 4,
    "ratio": 3.25
}

Deploying the API from scratch

The API was built taking advantage of the serverless framework. Hence, deployment is rather easy.

Install the serverless framework

npm install -g serverless

Go to the root directory of the project and deploy the API

serverless deploy -v

For further info visit: https://serverless.com/framework/docs/providers/aws/

What's missing?

• Test cases were not coded due to lack of time, but json input messages for the different mutant strands are provided.
• Validation of any kind: input messages are not being validated (eg.: expected json; valid DNA strands; etc.)
• Performance: since the API was built using a serverless architecture, it's highly scalable and should be able to handle heavy loads. Nonetheless, further fine-tuning can be done to make it even more reliable and increase it's performance such as:
  • Enable cache in AWS API Gateway for GET methods
  • Enable DAX for DynamoDB
  • Review function logic
• Resiliency
• ...and many other features