Yan Cui Profile picture
Sep 25, 2020 7 tweets 3 min read Read on X
Editing my conversation with @lajacobsson for @RealWorldSls and there's a nugget of insight that I wanted to share with you about implicit coupling that we often overlook when using SNS with SQS.

#serverless #aws

1/
The topic is usually owned by the publisher and deployed in the publisher's stack, and the subscriber would reference its ARN via a CloudFormation stack output or something, creating an implicit coupling there.

2/
You need message attributes to do filtering, but the publisher has no idea what the subscriber cares about (nor should it, loose coupling and all). So teams that own the subscriber have to ask the publisher's team to add the message attributes they need.

3/
This creates inter-team dependency and coupling. The subscribers no longer have the autonomy to do their thing, project momentum is lost as teams have to rely on other teams to review, merge and deploy their changes.

I've seen too many projects die due to this type of dep.

4/
AND, you're limited to 10 attributes per message, so for populate messages (like "order_created" in an e-commence app), it's also possible to actually run out of space!

5/
It's something that I hadn't thought about, even though I've had plenty of other reasons to prefer EventBridge over SNS these days: lumigo.io/blog/5-reasons…

6/
There's so much other good stuff in this conversation, can't wait to share with you all in a few weeks. Until then, check out the other conversations we have published already🤘

realworldserverless.com

end/

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More from @theburningmonk

Nov 14
One of the most misunderstood aspects of Lambda is how throttling applies to async invocations.

Or rather, how it doesn't!

🧵
With Lambda's Invoke API, you can choose invocationType as "RequestResponse" (ie, sync) or "Event" (i.e. async).



With sync invocations, throttling limits are checked to make sure you stay within:
* regional concurrency limit
* the function's reserved concurrencydocs.aws.amazon.com/lambda/latest/…
However, this is not true for async invocations.

The Event Invoke Frontend service accepts the request and passes it onto an internal queue.

Concurrency limits are not checked at this point and are instead applied later when the internal poller attempts to invoke the function synchronously.

If you want to learn more about how Lambda works under the hood, make sure you watch @julian_wood's fantastic session from re:Invent 2022.

youtube.com/watch?v=0_jfH6…Image
Read 5 tweets
May 7
SNS & EventBridge share many capabilities and can be used interchangeably in many situations.

So, how do you know when to use which? 🧵

#aws #serverless Image
Instead of purely judging by the difference in capability (which is an important consideration!) e.g., SNS has FIFO.

It'd be helpful to also consider their respective design choices and let them inform your choice.
SNS is optimized for 1-to-N communications, whereas EventBridge is for N-to-N communications.

This is subtly telegraphed in their respective limits and resource names.
Read 11 tweets
Oct 17, 2023
I have written over 800 technical articles in the last 14 years and they have been read millions of times.

I see a lot of folks making the same mistakes I did early on in my journey.

So here are some principles to help you get better at writing.

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1. 𝗦𝗲𝗹𝗹 𝘁𝗵𝗲 𝗽𝗿𝗼𝗯𝗹𝗲𝗺, 𝗻𝗼𝘁 𝘁𝗵𝗲 𝘀𝗼𝗹𝘂𝘁𝗶𝗼𝗻

Like that scene in The Wolf of Wall Street where Di Caprio asked Jon Bernthal to sell him a pen.

First, create the demand, then supply the solution. Image
Sell the problem to the reader. Help them understand why it’s a problem worth solving.

If the readers are not interested in the problem you're solving, they won't care about whatever solution you propose, no matter how good the solution is.
Read 16 tweets
Nov 22, 2022
This is big!

Payload-based filtering was one of the key reasons to choose EventBridge over SNS. This makes SNS a much more viable option in Event-Driven Architecture.

aws.amazon.com/blogs/compute/…
Off the top of my head, this would:

1. Allow you to use one SNS topic for many types of messages, previously one tends to have many SNS topics, one for each type of message.
2. Reduce the coupling between publisher and consumer teams.

e.g. no need for you to pester the publisher team to add a message attribute so you can filter their messages
Read 6 tweets
Oct 24, 2022
This is a very interesting thread and the surrounding discussions. I've had similar discussions in the past, but I don't want to make too many assumptions here because I wasn't part of the conversation with the client.

But here are my thoughts.

First of all, serverless has been successfully adopted at a much bigger scale in other companies. LEGO for example have 26 squads working mostly with serverless, and PostNL has been all in on serverless since 2018.

So technology is probably not the problem.
From the clues I'm able to pick up, the team has given it a go but they faced tooling gaps when you have both serverful (RDS) and serverless components, and maybe needed help to navigate those hard edges and adapt their practices to work better with serverless
Read 15 tweets
Aug 11, 2022
Serverless is great, but it's not a free lunch.

The "serviceful" mindset means you'll need to learn and use many services in your architecture. Having the right tool to help you along can make a world of difference. And here are 7 of my favourites.
Serverless IDE is a VSCode extension that will save you countless hours when you work with CloudFormation, AWS SAM or the Serverless Framework.

Auto-completion, schema validation, CF docs on hover, and many more.

marketplace.visualstudio.com/items?itemName…
IAM Legend by @TastefulElk is another great VS Code extension and takes the chore out of writing IAM statements.

Follow security best practices and do IAM role per function? This will save you hours of looking up IAM docs.

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Read 12 tweets

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