Cohesion vs. Coupling
“High cohesion, low coupling” is one of the most cited, and yet, most misunderstood principles in software engineering.
So in this short post, let’s explain their difference with a few easy-to-understand examples.
Year in review, 2024
2024 was the year I got back and amongst the community, and it felt great to be back!
If numbers tell a story, then my 2024 numbers is the story of a busy bee :-P
– launched 2 MVPs for clients
– 52% newsletter open rate
– 350+ workshop students
– $10,000 wasted on ads ?
– 33 blog posts
– 353k blog views
– 255k blog visitors
– 13k newsletter readers
– 50 newsletter issues
– 31 public talks
– 16 podcast episodes, 17k listens, 26k views
– 34 YouTube videos, 130k views, 6500 hours watched
– 420 LinkedIn posts
– 8.9M LinkedIn impressions
– 71k reactions
– 6250 comments
How to end-to-end test microservices across bounded contexts?
There is more than one way to test user journeys that span multiple bounded contexts. Your choice depends on organizational structure, team responsibilities, and the maturity of your testing practices.
Ultimately, every part of the user journey should be tested, whether it’s done piecemeal by individual teams or centrally by a QA/cross-functional team.
In this article, let’s look at several ways you can approach this problem, depending on if you have full-stack teams or specialised frontend and backend teams. We will look at trade-offs and whether it’s best to host other teams’ services in your environment, or use mock APIs, or delegate testing user journeys to a QA team and use a dedicated integration environment for testing.
How to invalidate Cognito-issued JWT tokens
The ability to invalidate a user’s session with immediate effect is a common enterprise requirement.
However, this goes against how token-based authentication is designed to work. JWT tokens are stateless and are typically short-lived (for security reasons) but can be refreshed with refresh tokens.
So, is it possible to invalidate Cognito-issued JWT tokens?
The short answer is no.
The long answer is yes, you can achieve this effect with some work and some performance overhead.
How? Well, come in and find out!
Biggest re:Invent 2024 serverless announcements
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 …
Biggest pre:Invent 2024 serverless announcements
DynamoDB cuts on-demand price by 50% Announcement DynamoDB has reduced on-demand pricing by 50% and global tables by up to 67%. Amazing! Lambda SnapStart is now available for Python and .Net Announcement Previously, SnapStart was only available for Java. It makes sense to add support for .Net. But why Python and not Node.js? I guess …
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Here is one of the most misunderstood aspects of AWS Lambda
One of the most misunderstood aspects of Lambda is how throttling applies to async invocations. Or rather, how it doesn’t!
The TL;DR is that you will never experience throttling when you invoke a function asynchronously.
It also means that despite SNS and EventBridge having longer retry periods than Lambda’s internal queue, these have no practical impact in the case of Lambda throttling.
Read the full post to understand why.
When to use Light Events vs. Rich Events in Event-Driven Architectures
One under-appreciated aspect of designing an Event-Driven Architecture (EDA) is how much information you should include in your events.
Do you send light events or rich events?
Or perhaps you would send both, but in different circumstances?
In this post, let’s talk about the pros & cons of each and how they fit into my mental model of DDD and EDA.
EventBridge best practice: why you should wrap events in event envelopes
This article is about best practices for building event-driven architectures on AWS, with a focus on wrapping events in custom envelopes when using EventBridge.
While EventBridge provides metadata by default, a custom envelope allows for a standardized, consistent structure across all of your events, making it easier to manage and evolve the system over time.
By providing your own metadata, you can gain better interoperability between different services, end-to-end observability, idempotency control and versioning.
Should “serverless” just mean “function-as-a-service”?
Gregor Hohpe said something that has me mulling over for some time now. Essentially, he asked, “Should we narrow the definition of serverless to mean just function-as-a-service (FaaS)?” “Serviceful” For context, I’m firmly in the “serverless means serviceful” camp: a) Serverless is a mindset: To leverage managed services to deal with undifferentiated heavy lifting so …
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