During this week's live Q&A session, a student from the Production-Ready Serverless boot camp asked a really good question (to paraphrase): "When end-to-end testing an Event-Driven Architecture, how do you limit the scope of the tests so you don't trigger downstream event consumers?" This is a common challenge in event-driven architectures, especially when you have a shared event bus. The Problem As you exercise your system through these tests, the system can generate events that are consumed...
about 2 months ago • 2 min read
I recently helped a client launch an AI code reviewer called Evolua [1]. Evolua is built entirely with serverless technologies and leverages Bedrock. Through Bedrock, we can access the Claude models and take advantage of its cross-region inference support, among other things. In this post, I want to share some lessons from building Evolua and offer a high level overview of our system. But first, here’s some context on what we’ve built. Here [2] is a quick demo of Evolua: Architecture This is...
2 months ago • 4 min read
"High cohesion, low coupling" is one of the most misunderstood principles in software engineering. So, let's clear things up! TL;DR Cohesion is about the internal focus of a thing - how well its components work together to fulfil a single purpose. Coupling is about the external relationships between things - how much they depend on one another. Cohesion When applied to a code module, cohesion measures how closely related its functions are. An Authenticator module will likely have high...
3 months ago • 1 min read
This edition of the newsletter is written by Raj Saha, Principal Solutions Architect working at AWS where he designed multiple world-scale systems. He has trained students to get SA jobs through his bootcamp, and runs a YouTube channel "Cloud With Raj" with over 114K subscribers. Since all of you Yan’s readers are pretty savvy technically, let me go over how to represent your technical knowledge in the (in)famous STAR format, to get hired at high paying jobs. All big tech companies, including...
3 months ago • 4 min read
2024 was the year I got back and amongst the community, and it felt great to be back! Blog I published 33 new blog posts. As a whole, my blog garnered 353k views from 255k visitors. About half of them came through Google search. This is down from 2023... but the decline is offset by more people reading my content through my newsletter nowadays. Most read blog posts: Hit the 6MB Lambda payload limit? Here’s what you can do When to use Step Functions vs. doing it all in a Lambda function How to...
3 months ago • 4 min read
One of my favourite questions from the November cohort of Production-Ready Serverless [1] is, "How do you handle e2e tests involving multiple services across bounded contexts?" In a microservices environment, testing user journeys that span across multiple bounded contexts requires collaboration and a clear delineation of responsibilities. Depending on how your organisation is structured, different teams are responsible for testing parts or the entirety of the user journey. For example... The...
4 months ago • 4 min read
The ability to invalidate a user's session with immediate effect is a common enterprise requirement. For example: If a user's credentials are compromised, we need to immediately revoke the user's access and force the user to change credentials. If an employee is terminated or an external contractor's access is revoked, their session should be invalidated immediately to prevent misuse. Many regulations mandate strict access controls and the ability to prevent unauthorized access in real time....
4 months ago • 3 min read
So that's it for this year's re:Invent. Werner delivered his usual insightful keynote and shared some key lessons in dealing with complexity and warning signs to look out for. As Werner said, the number of moving parts is not a good measure of complexity on its own. And that's something so many people get wrong about serverless - that they judge complexity by the no. of components on an architecture diagram. Ok, on with the serverless announcements. Aurora DSQL (pronounced "dee-sequel")...
4 months ago • 2 min read
One of the most misunderstood aspects of Lambda is how throttling applies to async invocations. Or rather, how it doesn't! Every Lambda invocation has to go through its Invoke API [1], whether you're invoking the function directly or through an event source such as API Gateway or SNS. With the Invoke API, you can choose invocationType as either "RequestResponse" (i.e. synchronous) or "Event" (i.e. asynchronous). Synchronous invocations With synchronous invocations, throttling limits are...
5 months ago • 2 min read
