Can Agile/XP go together with layered approach?
Should Agile/XP go together with layered approach?
Breaking the source code into layers requires extra efforts and thereby increases the development-time significantly.
N.B : By 'Layers' I mean separate assemblies with POCO, DA, etc.
Agile/XP is an approach to managing your project activities, deliverables and timelines.
Layered (N-tier) applications are a way to improve maintainability, scalability, and the ability for team members separate areas of responsibility.
They don't have much to do with each other, except that they both will require an additional investment in time if you're not familiar with each. Both will tend to improve the quality of your project if used properly, compared to traditional alternatives.