The dual-vee model is an extension of V-model. It is technically defined as a process of maintaining "system of systems". This model can be classified as Architecture Vee and Entity Vee. The Dual Vee model can be picturised as the letter V in english alphabet. It can be related to the conventional vee model where there exists a test plan corresponding to each phase of Sofwtare Development Life Cycle.
A system as a whole consists of various entities. Each entity integrated together forms a complete system architecture. So precisely, an Architecture Vee manages the system and the Entity Vee manages the subsystem.
The anatomy of a 'Dual Vee Model' is, while developing a complex software application there are a lot of facts to be considered, therefore the model presents the application’s ‘architecture’ in one ‘V’ and each component or entity of that completes the architecture. Hence the dual vee model is always represented as two overlapping V's, implying an association among entities and how those entities communicate to form a complete system architecture.
Let us understand this with the help of a real world example. For instance, a GPS needs a collection of satellites,a ground control network and of course it's users. So there needs to be a control mechanism at the ground to control the functioning of the whole GPS system. This entire system of GPS represents an architechture vee and each component of it an entity vee.
The diagram can referred to a 'GPS Architecture', that is, the way the entire system operates and the subsystems which form an important part at the various layers are - base station, internet, local/web server via which the final transmission to the destination systems take place.
Now let's discuss the two Broad classification of the model in greater detail.
Since the inception of a dual vee model,the system engineer must have a system baseline under the scanner.
One should be ready with the design documents,user manuals and the product when delivered must convey an answer, whether it solves the purpose it was meant for or not.
However with the progress in the development phase,there are bound to be changes in the baseline.As layers get added in project's development cycle, so does its complexity. Therefore architecture vee constantly emphasises on building the right product with the right resources.
The Architecture Vee can be understood as the one where there exists an integration,verification and validation planning for the overall system as well as for the subsytem. There exists a series of verfication and validation activities like – are we building the right product , is the product being built correctly?
This model comprises of integration among entities. How each entity can be collaborated with the other.
The topmost layer deals with stakeholder requirements which requires validation in the form of customer confirmation. The next subsequent phases are defining entity requirements,architechture selection,design the architecture and then finally building the code. These can be categorised as left side activities of the Vee model. So technically it is the left leg of the Vee.
The right leg of the Entity Vee states the verification mechanisms to be used on the right corresponding to the left side activities.
The dual Vee model emphasises on the fact that with each activity that is planned from the very beginning till the end product is realeased, there has to be a certain step by step planning alongside the activities carried out. There is an upward communication with the stakeholders that checks whether the end product suits their requirement. Whereas the downward communication helps in determining the best approach to be adopted for the Vee model.