4+1 View Model

This reading is about the 4+1 view model, its advantages and how it is used. Philippe Kructhen originally presented the 4+1 View Model to describe the architecture of software-intensive systems. This model is actually used to separate different stakeholders concerns it is widely accepted by the software industry to represent application architecture blueprints.

For the stakeholders architecture means different things i.e a Network Engineer would only be interested in hardware and network configuration of the system, a Project Manager in the key components to be developed and their timelines, a Developer in classes that makeup the component and so on. This is exactly where the 4+1 View Approach will aid us, it is an architecture style to organize an application architecture representations into views to meet individual stakeholder needs. The following image describes the 4+1 Model:

Logical View - Focuses on the realizing an application's functionality in terms of structural elements, key abstractions and mechanisms. Architects use this view for functional analysis.

Process View - This view considers the non-functional requirements such as performance, scalability and throughput, it addresses the issues of concurrency, distribution and fault tolerance.

Implementation or Development View - This is a view of a system's architecture that encompasses the components used to assemble and release a physical system. It focuses on configuration management and actual software module organization in the development environment.

Deployment View - This view encompasses the nodes that form the system's hardware topology on which the system executes; it focuses on distribution, communication and provisioning.

And finally and most important the Use Case View - It encompasses the use cases that describe the behavior of the system as seen by its end users and other stakeholders. This view represents the scenarios that tie the four views together, and forms the reason why all the other views exist. With all other views in place, this view seems redundant (hence +1).

The 4+1 Model will help us to approach the different views that stakeholders might need, this way it will show the usefulness of it and will achieve the main goal of the UML, to communicate the requirements to the stakeholders of the project. This is it for today folks! I will see you next time.