what's the difference between application layer and business logic layer? I kind of understand that business layer provides business specific services and application layer couples business services and provides services to the end user (webservice, UI, etc) am i right?
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133answers:
5
+1
A:
As I understand it the business layer is in charge of the business decisions AKA the logic involving the protocols of the client.
The application layer are the raw processes that have nothing to do with business decisions.
Javier Parra
2010-04-13 15:21:40
+6
A:
To summarize:
The application layer consists of those elements that are specific to this application. So that would contain the UI, back-end processing for the UI, and any bindings between the application and your business logic layer. In a perfect world, this layer would not contain any logic of the business domain.
The business logic layer (BLL) contains logic specific to the business domain. Also, if you are going to create a separate BLL, this layer should contain logic that could be used by other applications as well as this one. For example, a set of web services exposing a well-defined API. This de-couples the BLL from your application and allows you the flexibility to build other applications on top of it in the future.
Justin Ethier
2010-04-13 15:21:53
Can you provide a source for this? Your first bullet sounds like what I normally hear referred to as the presentation layer.
Bill the Lizard
2010-04-13 15:31:18
Unfortunately, no. I took his comment to mean the layers of his code specific to the application, as opposed to a business-specific BLL layer. But you are right, normally `Application Layer` is used in the context of the OSI model.
Justin Ethier
2010-04-13 16:18:10
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A:
Within the confines of Multitier architecture, the application layer and the business logic layer refer to the same thing. (I think this is what you're talking about.)
The term Application Layer is also used in protocol stacks, which can be confusing, but it's not really related. In this context it really encompasses all tiers of your application.
Bill the Lizard
2010-04-13 15:24:10
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A:
That sounds about correct.
The business layer implements the Domain Model in a boundary-technology-neutral way. In other words, it doesn't depend on any particular UI or service interface-related technology, such as web libraries or windowing APIs. You should be able to consume the business layer from any type of application - web, rich client, web service, etc.
The application layer bridges the gap between the business layer and the boundary techology.
Mark Seemann
2010-04-13 15:25:44
A:
I think of it as infrastructure. Depending on the application, it can contain the plumbing for configuration, reporting, the UI shell, etc.
Big Endian
2010-04-13 15:26:43