What is the Shared Kernel in Domain-Driven Design?

[@MilanJovanovicTech]

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[@aweklin]

Love this series. This is the exact same thing I did in one of my projects... Just made life much easier.

[@MilanJovanovicTech]

Awesome! :)

[@saddamhossaindotnet]

Love this series my friend. Keep up the awesome work! 🙂

[@MilanJovanovicTech]

Glad you enjoy it!

[@woendi]

Love this series. Keep up the good work!

[@MilanJovanovicTech]

Glad you enjoy it!

[@kasunjalitha2300]

Wow great! This is something I asked previously. Thank you so much 😊 please keep up the good work.

[@MilanJovanovicTech]

My pleasure 😊

[@acodersjourney]

Great video! Thanks for sharing your insights and knowledge.

[@MilanJovanovicTech]

Glad it was helpful!

[@mylesdavies9476]

Great video. A video on Nuget and publishing options would be good as it was mentioned at the end.

[@MilanJovanovicTech]

Yeah, great idea actually. As this is the easiest way to distribute a Shared Kernel :)

[@Rhazizi]

Great video! Thanks for sharing your knowledge.

[@MilanJovanovicTech]

Glad you enjoyed it! :)

[@savedbygrace8061]

Would you consider adding classes from the application layer like the logging pipeline behavior to the shared kernel?

[@MilanJovanovicTech]

No - the Shared Kernel should be applicable for the domain primarily.

[@krccmsitp2884]

The Domain should always follow the Infrastructure Ignorance Principle, and you don't want to have leaky abstractions here.

[@mohamedal-qadeery6530]

Can you show Authentication using Identity following DDD ? thanks for your video

[@MilanJovanovicTech]

Yes

[@PeterPeter-jz1hb]

What are benefits using IDateTimePrivider in shared kerner?

[@MilanJovanovicTech]

Being able to use it from Domain services

[@sunzhang-d9v]

how use@@MilanJovanovicTech

[@juankasem4911]

Thanks for the video. I believe I've got a couple of questions to ask, however. First, Isn't referencing the shared kernel project in the domain layer violating one of the clean architecture principles which states that the Domain layer should be independent and free of any other project references.? second, Should we create service classes in the domain layer to contain the logic & validations rather than doing that in the application layer (command & query handlers)? and in that case what would be the return type in those handlers, should we use the Result pattern there too?

[@MilanJovanovicTech]

- No, referencing the Shared Kernel isn't a problem. It's just an extension of the Domain anyhow - Domain services are helpful, but I wouldn't overuse them

[@pedrosilva1437]

I think you should have shown some shared entities and/or value types in this shared kernel video. It would be more representative of how that is described in DDD.

[@MilanJovanovicTech]

Agreed

[@SiyawashZahedi]

For Each bounded context we have four layers (domain, app, infra, Presentation)?

[@MilanJovanovicTech]

Bounded context is most relevant to the Domain

[@SiyawashZahedi]

@@MilanJovanovicTech so we have multiple Domain projects?

[@sunzhang-d9v]

error :("Email.Empty", "Email is empty"), everytime print :("The value of a failure result can't be accessed")?

[@MilanJovanovicTech]

Good thing

[@sunzhang-d9v]

return new Email(email); return type is Result ,why? no error?

[@MilanJovanovicTech]

Implicit operators

[@gusflopes]

I didn't get the reason behid the DateTimeProvider. Doesn't it already exists as default in the language? The purpose is to limit to only use UtcNow or something?

[@MilanJovanovicTech]

It was only added in .NET 8

[@gusflopes]

@@MilanJovanovicTech thanks for clarifying 👍

[@svorskemattias]

No, this is wrong, I think. This is not what a Shared Kernel is. The Shared Kernel is a Bounded Context just like other forms of Bounded Contexts. It contains domain entities that teams agree to share because they are so common! All teams that are invited to use the bounded context should have a say in how changes are to be made within the Shared Kernel. The base Entity model, Result object etc just belongs in some library. They´re just technical aspects of implementing DDD in whatever language and won't show up in your context map.

[@MilanJovanovicTech]

Well, if you watch the part where I talk about the share diagram - that's basically what I said

[@svorskemattias]

The share diagram?

[@clem_grim]

I totally agree, I was thinking the same. This video is more about "how to share common base classes to reduce duplication" and that does not seem related to what a shared kernel is in DDD.

[@sunzhang-d9v]

public static implicit operator Result(Error error) => Failure(error); ok?

[@MilanJovanovicTech]

Implicit can't know the generic argument

[@ahmedgaber3714]

Thank you ♥️ . What is your theme

[@MilanJovanovicTech]

ReSharper syntax highlighting

[@sunzhang-d9v]

public static implicit operator Result(TValue? value) => value is not null ? Success(value) : Failure(Error.NullValue); Email create() , return null, Not executed ，It feels like a lot of error value tests are problematic，

[@MilanJovanovicTech]

Can't use the generic version with implicit operator

[@sunzhang-d9v]

public static implicit operator Result（TValue？ value） => value is not null ？Success（value） ： Failure（Error.NullValue） Isn't that what the video shows？ why see : Can't use the generic version with implicit operator @@MilanJovanovicTech

[@kasunjalitha2300]

How about making a video regarding multiple IdentityUsers in same application with best practices? Customizing IdentityUser with strongly typed Ids for rich domain model etc... 🤞

[@MilanJovanovicTech]

Identity is on the list, it's coming!

[@bas10oli4]

No datetimeoffset 😮

[@MilanJovanovicTech]

Never needed it 🤷‍♂️

[@krccmsitp2884]

When you're using UTC-only date and time value, there is no reason to use DateTimeOffset at all.

[@SalmanShafiq-y3q]

That's what i am looking for ❤❤ if i use multiple project for multiple bounded context, then should i keep the common thing in application project in SharedKernel? Like, Behaviour, Caching, Some Contracts like ICommand, IQuery etc?

[@MilanJovanovicTech]

I typically have a few projects with cross-cutting concerns. One for each CA layer. So that i don't mix these responsibilities. But you can freely keeping everything in one project, if you want to.

[@lukaskuchta1010]

Shared kernel is something like building blocks for multiple contexts, isn't it ?

[@MilanJovanovicTech]

Yes

[@svorskemattias]

No

[@andreibicu5592]

Hi Milan. I usually like your videos and I am 99% into agreement with what you do. Now it's different. 1. I see you marked your domain model as an entity. Shouldn't the entities be a separate model used to map the structure of the tables? This seems wrong. 2. I don't see a reason in adding the validations for the Result class. Why would you throw an exception if the purpose of the Result class is to eliminate that? 3. I would group all the Result types together (Fluent related), but separate from the other abstractions that have no Fluent meaning. I hope this will make sense for you too!

[@MilanJovanovicTech]

1. This is a DDD Entity concept (not an EF entity) But I will still use the same class to map to DB, no need for duplication 2. Defensive coding 3. What do you mean?

[@rcstann]

It's a good, bloody thing that KZbin lets me stop and restart repeatedly. This moves along at a rather surrepitis pace but does eventually click.

[@MilanJovanovicTech]

Learned a new word today 😁

[@KritX01]

I see more microphone than face

[@MilanJovanovicTech]

Look closer

[@adeysam5475]

@@MilanJovanovicTech 🤣

[@microtech2448]

I don't get it. Separating out those abstractions into another project, how that is helping you better manage things. If there were some projects which should not reference domain project just for the Result or its generic version then it makes sense else that all seems a lot of work. That's my opinion.

[@MilanJovanovicTech]

Think about using this across your teams/projects

[@sunzhang-d9v]

😘

[@MilanJovanovicTech]

😁😁

[@baranacikgoz]

I love your videos, but your Result monad implementation (at this video and previous videos, all) really shallow. Only having bind and match does not make 'Result', Result monad should be applicative functor, should have Apply and many more methods

[@MilanJovanovicTech]

You can implement as many or as few of those as you need for the project. This implementation is pretty "complete" for the current project requirements. If I need more in the future, it's not a big deal to add it...

[@krccmsitp2884]

The Result Type pattern and monads are first of all distinct concepts. It is mostly desirable to implement a Result type as monad, but you're not obliged to it.

[@kodindoyannick5328]

Great video! I like it. Thanks Milan!

[@MilanJovanovicTech]

Glad to hear that!

[@sunzhang-d9v]

😘

[@MilanJovanovicTech]

✅