Design Considerations for Mobile Development
Decide if you will build a rich client, a thin Web client, or rich Internet application (RIA)
If your application requires local processing and must work in an occasionally connected scenario, consider designing a rich client. A rich client application will be more complex to install and maintain. If your application can depend on server processing and will always be fully connected, consider designing a thin client. If your application requires a rich user interface (UI), only limited access to local resources, and must be portable to other platforms, design an RIA client.
Determine the device types you will support
When choosing which device types to support, consider screen size, resolution (DPI), CPU performance characteristics, memory and storage space, and development tool environment availability. In addition, factor in user requirements and organizational constraints. You may require specific hardware such as a global positioning system (GPS) or a camera, which may impact not only your application type, but also your device choice.
Design considering occasionally connected, limited-bandwidth scenarios when required
If your mobile device is a stand-alone device, you will not need to account for connection issues. When network connectivity is required, mobile applications should handle cases when a network connection is intermittent or not available. It is vital in this case to design your caching, state management, and data-access mechanisms with intermittent network connectivity in mind. Batch communications for times of connectivity. Choose hardware and software protocols based on speed, power consumption and chattiness, and not just on ease of programming.
Design a UI appropriate for mobile devices, taking into account platform constraints
Mobile devices require a simpler architecture, simpler UI, and other specific design decisions in order to work within the constraints imposed by the device hardware. Keep these constraints in mind and design specifically for the device instead of trying to reuse the architecture or UI from a desktop or Web application. The main constraints are memory, battery life, ability to adapt to difference screen sizes and orientations, security, and network bandwidth.
Design a layered architecture appropriate for mobile devices that improves reuse and maintainability
Depending on the application type, multiple layers may be located on the device itself. Use the concept of layers to maximize separation of concerns, and to improve reuse and maintainability for your mobile application. However, aim to achieve the smallest footprint on the device by simplifying your design compared to a desktop or Web application.
Design considering device resource constraints such as battery life, memory size, and processor speed
Every design decision should take into account the limited CPU, memory, storage capacity, and battery life of mobile devices. Battery life is usually the most limiting factor in mobile devices. Backlighting, reading and writing to memory, wireless connections, specialized hardware, and processor speed all have an impact on the overall power usage.
Reference: Codeplex (Microsoft Patterns and Practices)