The following four layers are the most common layers in a logical multilayered architecture for an information system with an object-oriented design:
- Presentation Layer (a.k.a. UI Layer, View Layer, Presentation Tier.)
- Application Layer (a.k.a. Service Layer or GRASP Controller Layer )
- Business Layer (a.k.a Business logic layer (BLL))
- Infrastructure Layer (Data access layer, Persistence layer, Logging, Networking, and other Services which are required to support a particular Business Layer.)
Some common purposes of the above four layers are for example described in the book about domain-driven design at page 68-74, which is a book that otherwise is focused on describing the Domain layer
Sometimes there is no explicit distinction between the Business Layer and the Application Layer, e.g. the Application Layer is considered as being a part of the Business Layer. On the other hand, it is also possible to even further divide the Application/Business Layers into more layers. For example, if the Model View Presenter pattern is used, then you can consider the Presenter Layer as being a layer between the User Interface Layer and the Application Layer.
The Business Layer can also use a Business Infrastructure Layer (aka low-level business 'services' layer) logically positioned between Business Layer(s) and Infrastructure Layer(s). That layer (BI) is very general and can be used in several application tiers, e.g. a CurrencyConverter.
The Infrastructure Layer may be partitioned into different levels (high-level or low-level technical services). Though, it is not unusual that developers only consider the persistence (data access) and therefore only talk about the Persistence Layer or the Data Access Layer (instead of an Infrastructure Layer or Technical services Layer). In other words, the other kind of technical services are not always being explicitly thought of as being part of any particular layer.
Regarding that all types are not always considered as belonging to one particular layer, according to the "POSA book" (Pattern-Oriented Software Architecture A System of Patterns, page 39) a relaxed layered system (as opposed to a strict layered system) can use so called "shared data definition modules" which are types not belonging in a particular layer.
Famous quotes containing the words common, layers, information, system, logical and/or architecture:
“There comes Poe, with his raven, like Barnaby Rudge,
Three-fifths of him genius, and two-fifths sheer fudge.
Who talks like a book of iambs and pentameters,
In a way to make people of common sense damn metres,
Who has written some things quite the best of their kind,
But the heart somehow seems all squeezed out by the mind.”
—James Russell Lowell (18191891)
“I think its the real world. The people were writing about in professional sports, theyre suffering and living and dying and loving and trying to make their way through life just as the brick layers and politicians are.”
—Walter Wellesley (Red)
“Information networks straddle the world. Nothing remains concealed. But the sheer volume of information dissolves the information. We are unable to take it all in.”
—Günther Grass (b. 1927)
“[Madness] is the jail we could all end up in. And we know it. And watch our step. For a lifetime. We behave. A fantastic and entire system of social control, by the threat of example as effective over the general population as detention centers in dictatorships, the image of the madhouse floats through every mind for the course of its lifetime.”
—Kate Millett (b. 1934)
“I see mysteries and complications wherever I look, and I have never met a steadily logical person.”
—Martha Gellhorn (b. 1908)
“Poetry is not only dream and vision; it is the skeleton architecture of our lives. It lays the foundations for a future of change, a bridge across our fears of what has never been before.”
—Audre Lorde (19341992)