patterns & practices: App Arch Guide 2.0 Knowledge Base

Checklist – Mobile Application

Design Considerations

• You have determined the device types you will support.
• You have designed the application with occasionally-connected limited-bandwidth scenarios in mind.
• The user interface design is appropriate for the mobile device.
• You did not try to reuse a desktop application design or user interface.
• You have considered device resource constraints for battery life, memory size and program speed.

Authentication and Authorization

• You have designed authentication for over-the-air, cradled synchronization scenarios, Bluetooth discovery, and local SD card scenarios.
• You have considered that different devices may have variations in their programming security model, which can affect authorization to access resources
• You did not assume that security mechanisms available on larger platforms will be available on a mobile platform.
• You have designed authentication for access to Bluetooth devices.
• Trust boundaries are identified within your mobile application layers.

Caching

• Performance objectives are identified, such as minimum response time and battery life.
• You are caching static data that is useful, and avoided caching volatile data.
• You have considered data caching requirements for occasionally-connected scenarios.
• Your design supports low memory detection, and prioritization of data to discard, as available memory decreases.
• You chose the appropriate cache location, such as on the device, at the mobile gateway, or in the database server.

Communication

• Your design supports asynchronous, threaded communication to improve usability in occasionally-connected scenarios.
• You have considered the effects of receiving a phone call during communication or program execution.
• Communication over un-trusted connections, such as Web services and other over-the-air methods, is protected.
• You have considered using Web services for communication when you must access data from multiple sources, interoperate with other applications, or work while disconnected.
• You have considered message queuing when you need guaranteed delivery, asynchronous messaging, message security, or transaction support.

Configuration Management

• Your design supports the saving and restoration of configuration data after a device reset.
• Merge replication with a “buy and configure” application from a third party is used, if the enterprise data is in Microsoft SQL Server 2005 or 2008 and desire an accelerated time to market.
• You are using a binary format instead of XML for configuration files due to memory limitations.
• You are protecting sensitive data in device configuration files.
• You have considered using compression library routines to reduce the memory requirements for configuration and state information.
• You have considered using the Mobile Device Manager interface to manage group configuration of devices when you have an Active Directory infrastructure.

Data Access

• You have designed application to ensure data integrity.
• You are using the device database services (such as SQL Server Compact Edition) when your application must access a disconnected database.
• You are using merge replication to synchronize large volumes of data in one operation over a high bandwidth network connection.
• You have considered the overall size and impact on performance when you use XML to store or transfer data.
• You are using custom data transfer objects instead of DataSets to reduce memory overhead and improve performance.
• You are using the Microsoft Sync Framework when you must synchronize individual sets of a data over a remote connection.

Debugging

• You understand debugging costs associated with devices you need to support.
• You are using an emulator for initial testing and debugging.
• You are using the device for final testing.
• You have tested fully-disconnected scenarios in the design.
• You understand that it may be difficult to maintain context between different types of code running on a device.

Deployment

• Your design supports over-the-air deployment when users must be able to install and update applications while away from the office.
• You are using ActiveSync to deploy your application when the application relies heavily on a host PC.
• You are using the post-load mechanism to automatically load your application immediately after the Windows Mobile OS starts up when you are deploying a baseline experience running on top of Windows Mobile.
• You have included multiple device executables in the CAB when you are using CAB file distribution.
• Application will be deployed using an SD memory card if the application will be run only at a specific site and you want to manually control distribution.

Device

• The application is optimized for the device by considering factors such as screen size and orientation, network bandwidth, memory and storage space, and other hardware capabilities.
• Device-specific capabilities have been considered that will enhance your application functionality, such as accelerometers, GPUs, GPS, haptic (touch, force and vibration) feedback, compass, camera and fingerprint readers.
• You have designed a core functionality sub set when you are developing for more than one device.
• You have considered adding customization for device-specific features, including functionality to detect when the code is running on a device that can utilize this functionality.
• You have created modular code that can be removed if separate executable files are required due to device memory size constraints.

Exception Management

• Your application is designed to recover to a known good state after an exception.
• You did not use exceptions to control logic flow.
• Sensitive information in exception messages and log files are not revealed to users.
• Unhandled exceptions are dealt with appropriately.
• You have designed an appropriate logging and notification strategy for critical errors and exceptions.

Logging

• You did not store sensitive information in log files.
• You have considered using the Mobile Device Manager to extract logs from mobile devices when you have an Active Directory infrastructure.
• You have considered using platform features such as health monitoring on the server, and mobile device services on the device, to log and audit events.
• You have considered logging in an abbreviated or compressed format to minimize memory and storage impact when you carry out extensive logging on the device.
• You have used OpenNetCF on the device if you do not require extensive logging.
• You have decided what constitutes unusual or suspicious activity on a device, and logged information based on these scenarios.

Porting

• The application was re-written in its entirety when porting a Rich Client application from the desktop.
• The user interface has been redesigned for the smaller screen size when porting a Web application to a mobile device.
• You have researched details to discover what code will port without modification when porting a RIA client.
• You have researched and utilized tools to assist in porting.
• You have tested the custom controls which when porting to a mobile application and based on the results decided to rewrite to find an alternative.

Power

• The user interface is not updated while the application is in the background.
• Communication methods that use the least amount of power necessary are used.
• Power profiles have been implemented to increase performance when device is plugged into external power and not charging the battery.
• Power consumption has been considered when using the device CPU, wireless communication, screen, or other power-consuming resources while on battery power.
• Device functionality is allowed to be powered down when not in use or not needed. Common examples are screen backlighting, hard drives, GPS functions, speakers, wireless communications.

Synchronization

• Your design supports recovery when synchronization is reset, and is able to manage synchronization conflicts.
• You have considered the Microsoft Sync Framework when you want easy-to-implement one-way synchronization.
• You have considered using merge replication synchronization when you must support bidirectional synchronization to SQL Server.
• You have considered including over-the-air synchronization in your design when users must synchronize data when away from the office.
• You have considered including cradled synchronization in your design when users will be synchronizing with a host PC.
• You have considered store and forward synchronization using WCF over email or SMS (text message) mechanisms.

User Interface (UI)

• You have provided the user with a visual indication of blocking operations; for example, an hourglass cursor.
• You did not place menu bars at the top of the screen as they are difficult to see when using a stylus or touch screen input.
• The design of your layout considers input from various sources. For example, making buttons large enough for devices that supports touch screen.
• Your design supports various screen sizes and orientations associated with devices you need to support.

Performance Considerations

• Your design supports configurable options to allow the maximum use of device capabilities.
• You have considered using lazy initialization to optimize for mobile device resource constraints.
• You have considered limited memory resources and optimized your application to use the minimum amount of memory.
• You have considered using programming shortcuts as opposed to following pure programming practices that can inflate code size and memory consumption.
• You have balanced performance requirements with power consumption requirements.