#aws

Overview of recommender system design, from a two-tower four-stage architecture to an AWS Personalize and generative-AI marketing solution, with a comparison of the two approaches.

Walkthrough of a TikTok-style two-tower recommender for H&M and an AWS Personalize plus Bedrock ad-copy solution, with a comparison of when to use each.

Notes on an adaptive A/B testing tool architecture that uses Amazon Bedrock and MCP to assign variants based on user context.

The AWS 7 Rs migration strategies (rehost, relocate, replatform, refactor, repurchase, retire, retain) and AWS Prescriptive Guidance on large portfolio migrations — move first, modernize later.

Explains how AWS VPCs relate to Regions, Availability Zones and subnets, including core VPC components, subnet types and CIDR examples.

A real story of an AWS Lambda bill exploding 70x from a copy-pasted Terraform memory setting, with the cost drivers and lessons for controlling it.

Analysis of the axios vulnerability chain (prototype pollution → CRLF injection → request smuggling) that bypasses AWS IMDSv2 and steals IAM credentials.

Explains the hostname routing pattern, which isolates API services by giving each one its own hostname, with typical use cases and trade-offs.

Explains the HTTP header routing pattern, where a request header selects the target service, action, version, or feature, along with its pros and cons.

Explains the path routing pattern, which groups APIs under one hostname and separates services by URI, with NGINX, API Gateway, and CloudFront implementations on AWS.

Describes the Circuit Breaker pattern, which stops a caller from repeatedly calling a failing or slow service, its three states, and how to build it on AWS.

Describes the Event Sourcing pattern, which stores every state-changing event in an immutable event store and rebuilds state by replay, with challenges and AWS implementations.

Describes the Hexagonal Architecture (Ports and Adapters) pattern for loosely coupled, independently testable applications, including how to apply it on AWS Lambda.

Describes the Retry with Backoff pattern, which automatically retries operations that failed from transient errors using exponential backoff and jitter, with AWS implementations.

Describes the Saga Choreography pattern, which keeps data consistent across services through event subscriptions instead of a central coordinator, with an AWS order-flow example.

Describes the Saga Orchestration pattern, which uses a central orchestrator such as AWS Step Functions to coordinate distributed transactions and compensating actions.

Describes the Strangler Fig pattern for incrementally migrating a monolith to microservices behind a proxy layer, with AWS implementations, benefits, and challenges.

Describes the Transactional Outbox pattern, which solves the dual-write problem by saving events in the same transaction as the data, using an outbox table or change data capture.