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:
“This was the noblest Roman of them all.
All the conspirators save only he
Did that they did in envy of great Caesar.
He only, in a general honest thought
And common good to all, made one of them.”
—William Shakespeare (15641616)
“The force of a death should be enormous but how can you know what kind of man youve 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 its ordinary murder.”
—Don Delillo (b. 1926)
“I believe it has been said that one copy of The Times contains more useful information than the whole of the historical works of Thucydides.”
—Richard Cobden (18041865)
“The golden mean in ethics, as in physics, is the centre of the system and that about which all revolve, and though to a distant and plodding planet it be an uttermost extreme, yet one day, when that planets year is completed, it will be found to be central.”
—Henry David Thoreau (18171862)
“It is possibleindeed possible even according to the old conception of logicto give in advance a description of all true logical propositions. Hence there can never be surprises in logic.”
—Ludwig Wittgenstein (18891951)
“Polarized light showed the secret architecture of bodies; and when the second-sight of the mind is opened, now one color or form or gesture, and now another, has a pungency, as if a more interior ray had been emitted, disclosing its deep holdings in the frame of things.”
—Ralph Waldo Emerson (18031882)