Re: Responsibilities of ApplicationServices versus DomainServices

Or other contexts etc.

On Monday, May 27, 2013, Wim van Gool wrote:

> **
>
>
> *Infrastructural Services*
> *- *To send mail or otherwise communicate (out) to external systems.
> *
> *
> *Application Services* (aka MessageHandlers)
> - Live in the ApplicationLayer.
> - Know about and handle messages of any kind (commands and events,
> external and internal)
> - Never contain any business logic, but delegate to the domain(services)
> for this.
> - Translates message-property values to Domain-instances where required.
> - May have some form of exception-handling to handle/convert exceptions
> raised by the domain.
>
> *Domain Services*
> - Live in the DomainLayer
> - Know nothing about messages - only plain arguments.
> - Primarily used to coordinate several calls to aggregates in one
> transaction, which should be a rather scarce case.
>
> *Remaining questions*:
> - Which service would you use to implement adding/removing aggregates and
> raise the appropriate DomainEvent?
>
>
> On Mon, May 27, 2013 at 11:44 AM, Greg Young <[email protected]<javascript:_e({}, 'cvml', '[email protected]');>
> > wrote:
>
>> **
>>
>>
>> Infrastructure service
>>
>> To send email
>>
>>
>> On Monday, May 27, 2013, Wim van Gool wrote:
>>
>>> **
>>>
>>>
>>> Everybody knows ApplicationServices and DomainServices are different and
>>> have different responsibilities. Yet, I think it would be convenient to
>>> have a clear list of what things should typically be handled by each
>>> service-type and what not. I'll kick it off by my own thoughts on the
>>> matter and hope others will correct me or help me complete the list (or add
>>> some open questions).
>>>
>>> *ApplicationServices* (aka MessageHandlers)
>>> - Live in the ApplicationLayer.
>>> - Know about and handle messages of any kind (commands and events,
>>> external and internal)
>>> - Never contain any business logic, but delegate to the domain(services)
>>> for this.
>>> - Translates message-property values to Domain-instances where required.
>>> - May have some form of exception-handling to handle/convert exceptions
>>> raised by the domain.
>>>
>>> *DomainServices*
>>> - Live in the DomainLayer
>>> - Know nothing about messages - only plain arguments.
>>> - Primarily used to coordinate several calls to aggregates in one
>>> transaction, which should be a rather scarce case.
>>>
>>> *Remaining questions*:
>>> - Which service would you use to implement adding/removing aggregates
>>> and raise the appropriate DomainEvent?
>>> - Which service would you use to send an email or otherwise call
>>> external services?
>>>
>>>
>>
>> --
>> Le doute n'est pas une condition agréable, mais la certitude est absurde.
>>
>>
>  
>


-- 
Le doute n'est pas une condition agréable, mais la certitude est absurde.