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:
“If we dreamed the same thing every night, it would affect us much as the objects we see every day. And if a common workman were sure to dream every night for twelve hours that he was a king, I believe he would be almost as happy as a king who should dream every night for twelve hours on end that he was a common workman.”
—Blaise Pascal (1623–1662)
“The force of a death should be enormous but how can you know what kind of man you’ve killed or who was the braver and stronger if you have to peer through layers of glass that deliver the image but obscure the meaning of the act? War has a conscience or it’s ordinary murder.”
—Don Delillo (b. 1926)
“So while it is true that children are exposed to more information and a greater variety of experiences than were children of the past, it does not follow that they automatically become more sophisticated. We always know much more than we understand, and with the torrent of information to which young people are exposed, the gap between knowing and understanding, between experience and learning, has become even greater than it was in the past.”
—David Elkind (20th century)
“When the finishing stroke was put to his work, it suddenly expanded before the eyes of the astonished artist into the fairest of all the creations of Brahma. He had made a new system in making a staff, a world with full and fair proportions; in which, though the old cities and dynasties had passed away, fairer and more glorious ones had taken their places.”
—Henry David Thoreau (1817–1862)
“The truth is, that common-sense, or thought as it first emerges above the level of the narrowly practical, is deeply imbued with that bad logical quality to which the epithet metaphysical is commonly applied; and nothing can clear it up but a severe course of logic.”
—Charles Sanders Peirce (1839–1914)
“It seems a fantastic paradox, but it is nevertheless a most important truth, that no architecture can be truly noble which is not imperfect.”
—John Ruskin (1819–1900)