4+1 Architectural View Modal
4+1 is a view model used for “describing the architecture of software-intensive systems, based on the use of multiple, concurrent views”. The views are used to describe the system from the viewpoint of different stakeholders, such as end-users, developers, system engineers, and project managers.
History & The Evolution
In 1995, Ma Philippe Kruchten introduced the 4+1 Software Architectural View Model in his paper of “Architectural Blueprints — The ‘4+1’ View Model of Software Architecture”. Where he had supported a various view modeling approach for programming structures, which the utilization case view is the bringing together view of the other four views.
There he characterized 4 simultaneous views according to the perspective of the different partners. The logical view, the process view, the physical view and the development view.
In 1996, he was appointed the Director of Process at Rational Software where he led the development of the “Rational Unified Process” (RUP). The 4 + 1 views are a key concept in the RUP section on Analysis and Design.
4+1 views model is an information organization framework; it includes logical, process, development, physical layout and end-user perspective information of an application.
This Logical view id for developers and Engineer managers. which captures the functional requirements of the application as decomposition of structural elements or abstractions. Which has 3 steps:
- Object Decomposition means capturing application behaviors into classes and packages. It is the base of functional analysis in case of Object-Oriented Paradigm. Classes can be represented by UML class diagrams and packages can be represented by UML package diagrams.
- Data modelling is the analysis of data gathering and organizing data into logical entities. ER diagrams can be used to represent entities and relationships.
- System and subsystems view is breaking down of application into modules and arrangement of their responsibilities and relationships. UML component diagram can be used.
Process view captures non-functional requirements such as, process, behavior, task concurrency, and flow of information. This view shows the processes rules of system and how they communicate with each others. UML diagrams such as sequence diagrams, communication diagrams and activity diagrams, can be used to represent the process view.
In Physical View, it represents the deployment layout or infrastructure of an application. In essence, it captures hardware mapping of application components or processes. Physical connections between software components will be concerned using UML diagrams.
This view focuses on the management of an application for managers and developers. This view is also known as implementation view. And it uses UML Components diagrams to describe system components.
In today’s world, The 4+1 Architectural View Model is rarely utilized. Engineers started to see less value in explicitly documenting the separate views, with rie of Service Oriented Architecture (SOA).
Why it is called “4+1” over “5”?
The use case view is unique in that it specifies a system’s high-level needs, whereas other views clarify how those requirements are implemented. It’s basically redundant after the other four perspectives are done. All other points of view, on the other hand, would be impossible to achieve without it.