There will be no coherent vision
There will be no overall guiding vision on the project or its architecture.
Vision is needed at several stages and in several forms during the course of a project. The enterprise must have a vision that drives the business process design. The business process designers must have a vision of what a computerized system could do for them. The software vendor must have a vision of a product that would fill a need in the market. Out of one or more of these there will come a vision for the software development project, which aids in determining the scope of the project and identifying stakeholders. The requirements will form the basis upon which a vision of the logical and physical architecture of the system will be built. It is possible to progress without one or more of these ‘visions’, but at the risk of LackOfDirection and general wasted effort by heading in wrong directions.
Each project should ideally start with a VisionStatement stating what the project is to do and why it is doing it. This will aid in, but is not a necessary prerequisite to, establishing a UnityOfPurpose for the project team. Establish an Architect role, as described in ArchitectControlsProduct. One of the tasks of this role is to establish a technical vision for the product.
In modern Agile approaches, the business vision is assumed to be the responsibility of the customer, though he may require aid in establishing a coherent vision. The goals of the project are always to provide solutions to the highest priority requirements that the customer provides. Change is embraced, so there is less need to ‘get it right first time’ and thus less need for a guiding vision. XP has a particular variant of (architectural) vision known as the SystemMetaphor. DSDM defines a special role of Visionary to ensure overall business objectives are adhered to.