This document discusses several ways to call AWS Lambdas including through API Gateway, direct invocation, Step Functions, SNS, SQS, and Kinesis. API Gateway exposes Lambdas through public URLs but has limited error handling. Direct invocation uses IAM auth but requires handling errors. Step Functions provides graphical workflows for complex orchestrations. SNS is for publish/subscribe between decoupled services while SQS supports message queues, batching, and ordering. Kinesis can process large amounts of data across shards with retrying.

1. Hello Lambda!
How to Call Lambdas on AWS
David Roberts
Chain.io
@drobtravels

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API Gateway
● Expose Lambda to a Public URL
● 30s Timeout
● No error handling
● Some built in auth / rate limiting
features
Public APIs
Internal Microservices

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Direct Invoke / SDK
● Directly invoke Lambdas
● IAM authentication
● Sync or Async
● Must handle errors
Synchronous requests
❓Code Smell?

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Step Functions
● Graphical flow
● Visibility
Complex orchestrations
Constrained resources

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Simple Notification Service (SNS)
● Publish / Subscribe
● Retry handling
De-coupled Services
Constrained resources

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Simple Queue Service (SQS)
● Message Queue
● Batching
● FIFO queue allow guaranteed
ordering / exactly once
● Resiliency
Constrained resources
Decoupled services

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SNS to SQS
● Best of Both
● Downstream resources can control
flow independently
Constrained resources
Decoupled services

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Kinesis
● Retries really hard
● Poison Pills
● Sharding
Processing Large amounts of data
Constrained resources
Logging
Message Queue