Serverless Architecture

Serverless is a cloud-computing execution model which developers do not need care about the allocation of hardware resources (which will be managed by cloud providers).

Lambda

Lambda functions can be used in mainly two ways:
- Event-driven compute service: code is run in response to events, such as changes in S3 bucket or DynamoDB table;
- Normal compute service: code is run in response to HTTP requests via API Gateway (or AWS SDKs).
It is important to understand the tradeoff between traditional architecture vs serverless architecture.
- Traditional architecture (but on the cloud): ELB + EC2 + RDS (MySQL or PostgreSQL);
- Serverless architecture: API Gateway + Lambda + Aurora (or DynamoDB).
The pricing model of lambda functions is based on the number of requests + the compute duration.
Lambda scales out (but not scale up) automatically.
AWS X-ray can help to debug lambda functions when the architecture goes too complex.

Alexa is a cloud-based voice service provided by AWS.
It is possible to build custom skills for Alexa, which can then trigger lambda functions to perfom powerful actions.