Layer (or abstraction level, or a layer of abstraction) is a way of hiding the implementation details of a particular set of functionality.

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Trying to understand 3 layer programming [closed]

I am confused to understand the structure of a 3 layer programm. Where is good place for exceptions, entity and etc.? If I use MVC, in my UI model, how to transfer entity class to model class and etc.?...
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Why is it a good idea for “lower” application layers not to be aware of “higher” ones?

In a typical (well-designed) MVC web app, the database is not aware of the model code, the model code is not aware of the controller code, and the controller code is not aware of the view code. (I ...
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Why doesn't layered architecture translate easily to tiered architecture?

Basically, I'm trying to understand why layered and tiered are that different, and why they don't translate easily to each other. I understand that layered could be 3 separate class files for UI, BL ...
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Large teams with layered application

I work in a fairly large team (~15 developers) which is currently discussing our working methodology. The software we work on is quite feature-rich and expanding rapidly in terms of scope so the ...
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How do the Application and Database Interface Layers interact at their boundary?

I was watching one of Uncle Bob's videos and he brought up the Database Interface Layer. He had this diagram showing it: These arrows show that the DB Interface Layer is aware of and calls the ...
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Good practices to implement mappers in a multi-tier application

When you are working with a multi-tier application very often you run into task of converting objects in one layer to objects in another layer. This could be converting database objects into domain ...
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Presentation VS Application layer in DDD

I have trouble drawing a clear line between Presentation and Application layer in Domain Driven Design. Where should Controllers, Views, Layouts, Javascript and CSS files go? Is it in the ...
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When do domain concepts become application constructs?

I recently posted a question regarding recovering a DDD architecture that became an anemic domain model into a multitier architecture and this question is a follow-on of sorts. My question is when ...
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Do stored procedures violate three-tier separation?

Some colleagues of mine have told me that having business logic in stored procedures in the database violates the three-tier separation architecture, since the database belongs to the data layer ...
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PHP - Data Access Layer

I am currently reviewing a code base and noticed that a majority of the calls (along with DB connections) are just buried inside the PHP scripts. I would have assumed that like other languages they ...
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Processing a stream. Must layers be violated?

Theoretical situation: One trillion foobars are stored in a text file (no fancy databases). Each foobar must have some business logic executed on it. A set of 1 trillion will not fit in memory so the ...
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Does it make sense to use ORM in Android development?

Does it make sense to use an ORM in Android development or is the framework optimized for a tighter coupling between the UI and the DB layer? Background: I've just started with Android development, ...
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Event driven design and separation of core/UI logic

I am new to event driven development, and I feel lost when I try to implement events that should pass the core/UI boundary. In my program I have the following (example in c#): UI.RuleForm Core....
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Effective programming of data layer management/access

Short Version: What is the term/concept which describes the efficient design of programming the data layer for efficient data access and what are some sources/books/articles/website which discuss this ...
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Validation and authorization in layered architecture

I know you are thinking (or maybe yelling), "not another question asking where validation belongs in a layered architecture?!?" Well, yes, but hopefully this will be a little bit of a different take ...
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What are the pros and cons of implementing this requirement in different layers?

I have a CRUD app for <DomainObject>s. They are persisted in a database. There is a new requirement: keep track of the <DomainObject>s that have been created since the app was opened, ...
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n-layers architecture design, really worth the effort?

I was building an application in .Net for almost a year (almost alone), I took the decision to build it with a 3-layer design. Recently when finished the project, I analyzed if the effort of creating ...
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Entity Framework and “ViewModel”

Earlier I asked a question about "Entity Framework and layer seperation" and found out that some people use a ViewModel to show their data in the UI. For example if we got a "Person" table and an "...
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Entity Framework and layer separation

I'm trying to work a bit with Entity Framework and I got a question regarding the separation of layers. I usually use the UI -> BLL -> DAL approach and I'm wondering how to use EF here. My DAL would ...
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How to document/verify consistent layering?

I have recently moved to the dark side: I am now a CUSTOMER of software development -- mainly websites. With this new role comes new concerns. As a programmer i know how solid an application ...
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Recommended content for layers

As an expansion from my previous question about using separate projects for seperate layers - Good practice on Visual Studio Solutions I now wish to know if I am putting the right functionality in ...
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GUI, BLL, DAL Organization In A Project

I'm reading about application layers, and want to use this design in my next project (c#, .Net). Some questions: Is the separation of layers done through namespaces? Project.BLL.Whatever, Project....
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What are “User Process Components”?

This article about application architecture design mentions "User Process Components" as part of the presentation layer. User process components. Your user process components help synchronize and ...
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Can it be useful to build an application starting with the GUI?

The trend in application design and development seems to be starting with the "guts": the domain, then data access, then infrastructure, etc. The GUI seems to usually come later in the process. I ...