Commands & Events: What's the difference?

One of the building blocks of messaging are, you guessed it, messages! But there are different kinds of messages: Commands and Events. So what's the difference? Well they have very distinct purposes, usage, naming, ownership, and more!

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0:00 Intro
0:35 Commands
2:15 Events
3:37 In Combination
5:08 Code Example

#eventdrivenarchitecture #messaging #softwarearchitecture

[markovcd]

Procrastinaging at work. You posted this video just in time! :)

[MrAyuub]

Thanks for making this video! I was thinking what were the differences exactly when you replied to my comment

[mikeyim]

I was looking for exactly this. Perfect timing!

[osman]

Good video and I was wondering if there is more advanced reference example app that shows a kinda "real world" CreateOrder, PlaceOrder examples?

[garylafferty]

Thank you for the video!
Can we access your source code without having to sign up for a monthly fee?
Seems like everything is behind paywall these days.

[ruekkart]

From a CQRS point of view, how would the queries fit here? Would the HTTP API handle them directly or should each microservice expose its own query handlers and the main API just delegate the call?

[RM-bgcd]

Thank you for the video as always. May I ask where is the video hyperlink about types of events that you mentioned? Something about fat events, thin events, etc.

[haraheiquedossantos]

Is it normal to create Command messages from Integration Events inside an Integration Event Handler, and then call the CommandHandler?
I'm asking this because in eshopcontainers Microsoft project I saw many times creating a Command from a Integration Event (that acts like a consumer) inside Order bounded context. Is this the recommended way or depends of scenarios? Or is not necessary and I can do all logic inside my consumer/integration handler?

[thedacian]

So command handler resides on application area (are application services) rather then in Domain Model, and is it possible that an Bounded Context to contain more then one phisicall app?.Thanks!

[Zeft_Dylis]

Hello, thanks for your work. I didn't understand a point. Why CRUD should not be assimilated as commands ? From my comprehension, all commands are not CRUD but when a service asks to another to create an entity, it should be Seen as a command. Or am i wrong ?

[drewjaqua]

For clarity, when you say there is only one consumer for a command (but that events can have multiple consumers), are you suggesting that commands should/do conform to the produce-consume paradigm, while events conform to the publish-subscribe paradigm?