Difference between 3 tier and 3 layer architecture

Question

Vincent Maverick Durano · Answer

Your question has been asked many times before. Please try to do a quick search on google to get more informations about it. But just to give you a quick overview between them then here's my take on the subject: Tiers- A Tier is simply the physical separation of your app components. Layers- Layers act as more logical separators that exist to separate and organize your actual code. You'll often hear terms like Business Logic Layer Presentation Layer and others. These are simply ways to organize all of the code within your application. If you have a web app that contains your Data Access and Business Logic which is running on the same machine/Server then you will have 3-layered app in 1-Tier. Now if your Data Access is hosted on different machine/server and your Business is also hosted in different machine/server then you will now have a 3-layered app in 3-Tier.

Bikesh Srivastava · Answer

Hi this is the best answer.  N-tier and n-layer are entirely different concepts. People often use this term interchangeably during the design of the application architecture. N-tier refers to the actual n system components of your application. For ex: Suppose you create a web application its components include your application server where it is being hosted the database being used with it on another server and the user machine who access the application forms the third component. These are referred to as the 3 tiers of your application. So they may be n in number and so the term n-tier application. So tiers are the physically separate components of the same system . On the other hand layers refer to the internal architecture of your component. For ex: in your code you divide the code into different layers like Data access layer Business logic layer etc.. So they are internal to the component and these layers interact with each other internally to form the entire component.

Vinay Singh · Answer

Hi Logical layers are merely a way of organizing your code. Typical layers include Presentation Business and Data – the same as the traditional 3-tier model. But when we’re talking about layers we’re only talking about logical organization of code. In no way is it implied that these layers might run on different computers or in different processes on a single computer or even in a single process on a single computer. All we are doing is discussing a way of organizing a code into a set of layers defined by specific function. Physical tiers however are only about where the code runs. Specifically tiers are places where layers are deployed and where layers run. In other words tiers are the physical deployment of layers. check the link http://freefeast.info/tutorials-for-beginners/dotnet-tutorials/3-tier-vs-3-layer-architecture-difference-between-3-layer-and-3-tier-architecture/ http://www.hanselman.com/blog/AReminderOnThreeMultiTierLayerArchitectureDesignBroughtToYouByMyLateNightFrustrations.aspx