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

learn more… | top users | synonyms

6
votes
1answer
193 views

MVC - Do I create 'joint' layers when dealing with multiple models?

I'm new to MVC and the different layers architecture and this is what I have currently: 2 models: User, Company 2 service layers: UserService, CompanyService 2 interfaces which abstract the ...
0
votes
0answers
105 views

Is this approach scalable?

I am working to rewrite a legacy application (C++) to C# ASP.NET MVC with EF6 but plan to upgrade to ASP.NET Core1 and EF Core 1. The database schema is really arcane in that it has a single schema ...
5
votes
1answer
90 views

Choosing between Dependency Inversion and Dependency “Delegation” to a third module

Suppose I have MasterPackage containing a Master class, and BlasterPackage containing Blaster class. Since Master needs a Blaster to work, the higher level MasterPackage depends directly on ...
4
votes
1answer
73 views

Testing of a layered software architecture

I am currently building an application with a layered architecture in C. Currently, I have built and tested the bottom layer, which is a networking module, providing functionality such as ...
8
votes
3answers
725 views

Implementing a complexity hiding layer

As part of the dependencies that the project I'm working on has, we use several core services. These services, to which we can't make big changes, are a big mess. Depending on the method we invoke, we ...
1
vote
1answer
30 views

Can an outside component interact with lower layers directly in a strictly layered architecture

If we have a strictly layered architecture, can we allow outside components to interact directly with the lower layeres? More specifically: In my lower layers, I am providing a service, and in the ...
0
votes
2answers
146 views

In AngularJS - should $resource be used from controller or service?

All the documentation, examples and tutorials I've found on $resource were using it directly in the controller. So far I'm just using $http from services and those services are further used in the ...
1
vote
0answers
106 views

Refactoring to avoid circular references

I'm working on an ASP.NET MVC solution that has two projects, WebUI and DAL. WebUI references DAL. DAL has the repository and context, while WebUI contains Authentication and Authorization classes. ...
5
votes
2answers
183 views

Where should business logic go in a layered architecture?

First of all, i'm not talking about validation in the sense of the nullability or length of a field like in this and this questions where we can use isValid() methods in business classes or an ...
3
votes
3answers
151 views

Abstracton layer to control services access to denormalized db entity

Our db is optimized for minimum join count (partially denormalized). E.g. our User entity contains account data (nickname, facebook id, etc), user numerical statistics (total games played, total wins, ...
0
votes
0answers
42 views

Abstracting AutoLayout sensibly - why is this so conceptually tough and where should I begin?

Below are some babbling, probably incoherent thoughts, but I am so stuck on this problem and I feel like an elegant solution is possible. Though it is indisputably awesome, and makes programatic view ...
3
votes
1answer
352 views

OOP - How to refactor a “pyramid architecture”

Unbeknownst to me while I was building it, I built a "pyramid" architecture. I did not realize this until I laid it out in my new Visual Studio 2013 Layer Diagrammer. Each layer depends on the layer ...
1
vote
2answers
132 views

Do web applications use HTTP as a transport layer, or do they count as an integral part of the HTTP server?

Given an HTTP server (e.g. Apache, IIS) and a web application (user code running in the server using PHP, ASP.NET and the likes), which of those can decide which HTTP status code to return for any ...
4
votes
3answers
924 views

DDD, modularizing the application and domain layers without breaking the DIP

Quoting DDD theory: The application layer is thin in terms of domain logic - it merely coordinates the domain layer objects to perform the actual work. When it comes to modularization, and ...
3
votes
4answers
249 views

N-Layer architecture

I am attempting to structure my solution projects in such a manner as to improve testing, reuseability, separation of concerns and all that good stuff. Whilst I understand these concepts in theory, I ...
2
votes
6answers
960 views

Domain Model, validation, and pushing errors to the model

Looking into DDD and something I noticed is that business logic should be in the model, otherwise you just have property bags. That said how do you handle pieces of validation that require a trip to ...
0
votes
2answers
114 views

What layers reference each other in a multi layer design? [duplicate]

I'm creating a project and I'm having difficulty and contrasting opinions on how to do things when it comes down to separating layers. I'm not fully sure what layers should reference each other. I ...
1
vote
2answers
237 views

Where should the “not empty field” validation code be written on a 3-layer application?

When working with the 3-layer model, where should the validation code be placed? for: not empty fields, unchecked options, null values, wrong-written dates, etc. To keep total isolation between a ...
0
votes
3answers
1k views

Business Logic vs Presentation/View Logic

I often question myself of where to put the logic that organize the data to a view that is not necessarily a business logic in a 3-layered architecture (DAO, Business, View). I'll put an example to ...
1
vote
1answer
202 views

Confused about layered application development

So, for the first big project that I'm getting paid for, I decided I'd do things right. To that end, I've created several projects in my Solution. Some of these projects are generic and handle common ...
0
votes
2answers
246 views

Can a layer consist of multiple projects / dlls?

I am working on the architecture for a new web application and I am pretty much a complete newbie when it comes to architecture. Working my way through .NET Application Architecture Guide, 2nd Edition ...
2
votes
1answer
101 views

How to handle errors best addressed in a higher abstraction layer and dependent on state inferred in current layer?

I have a use-case that can be repaired, but the logic for repairing it is best done in a higher level of abstraction. Just throwing exception/failure is ugly because it's hard to pass back up through ...
3
votes
1answer
191 views

Where do utility libraries fit in a layered architecture?

Consider this mock-up of a software stack designed with layered architecture in mind : Every application layer is decoupled through API calls, but a memory handling library is used throughout. All ...
1
vote
1answer
299 views

Lazy Loading, DAL and BLL abstraction

I'm asking myself a question to code the right way on a new fresh project. I have a designed database and I mapped tables to equivalent POCO classes using Entity Framework 6 Code First. Then, I ...
4
votes
2answers
343 views

What are the advantages of strictly maintaining separate data | algorithm | interface layers?

I always separate the user interface from other functionality in my programs - its the way I have been taught, and it has obvious advantages since you can change the interface but keep the same ...
3
votes
2answers
195 views

Best practice for security checks, in surface or deep layer? [closed]

Let's take a server-side WebServices app, we need to make sure that all function applies every security rules, and keep the code clean. In such a case, I usually prefer to place my security checks on ...
1
vote
1answer
129 views

Data Access Layer for application

I am working on a retail application where currently I'm using raw SQL like insert into some_table values (Textbox1.Text, Textbox2.Text, ...) and update some_table set some_column = value for ...
1
vote
1answer
376 views

Where does non-MVVM code belong in an MVVM app?

By non-MVVM code, I mean things like highly generalized components, like one with common extension methods for CLR types, and other 'homeless' helper classes etc? I have a Core project that most ...
2
votes
3answers
3k views

What is an “abstraction layer”?

I need a very simple explanation because I'm not a professional programmer. I found the terminology "abstraction layer" reading the documentation of mysqli extension where is described the difference ...
2
votes
3answers
1k views

DAL vs BLL functions' return types

Here is how I see the main differences between the DAL and the BLL: The DAL directly query the database. The DAL doesn't create new information. It may execute complex sql requests, joining several ...
5
votes
1answer
239 views

How to avoid dragging arguments from function to function

When I do my code layout, I like to start with a rather high level view, and then start to delegate actual computation to class or functions that have a bit more detail. Then in these classes of ...
203
votes
11answers
53k views

How accurate is “Business logic should be in a service, not in a model”?

Situation Earlier this evening I gave an answer to a question on StackOverflow. The question: Editing of an existing object should be done in repository layer or in service? For example ...
6
votes
2answers
676 views

Is programming in layers real? [duplicate]

I am fairly new in product development and I am trying to work over a product. The problem that I have realized is that people draw diagrams and charts showing different modules and layers. But as I ...
0
votes
1answer
138 views

Layer style applied, but intuition is different

Currently, I'm developing an architecture for a system of the following kind: There are a couple of existing applications (front end) with which one can define UML profiles capturing some specific ...
0
votes
3answers
492 views

How do I create a simple yet complex business layer?

I'm working with a fairly complex web application. It's split up into the following layers: Presentation - HTML Service layer - A REST and SOAP API communicating with the business layer Business ...
2
votes
3answers
133 views

Efficiently “moving” data upward through a communication stack

I have implemented an application protocol stack that moves an incoming stream of data upward through several layers, as follows: copies a TCP segment from an OS buffer to my_buffer. after ...
2
votes
3answers
962 views

Which layer does async code belong?

I am developing an application that consumes data from an external service. The application is being implemented following a typical layered architecture with UI, Presentation, Domain and Data ...
0
votes
1answer
865 views

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 ...
61
votes
13answers
6k views

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 ...
3
votes
1answer
322 views

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 ...
5
votes
4answers
272 views

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 ...
5
votes
2answers
3k views

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 ...
5
votes
3answers
904 views

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 ...
3
votes
3answers
3k views

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 ...
1
vote
1answer
191 views

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 ...
28
votes
5answers
6k views

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, since the database belongs to the data layer whereas stored ...
0
votes
3answers
4k views

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 ...
7
votes
4answers
293 views

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 ...
23
votes
2answers
11k views

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, ...
1
vote
3answers
739 views

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 ...