Designing mobile applications

1. .NET Mobile Application Development
Designing Mobile Applications

2. Introduction
 In previous sessions we have considered
> Characteristics of mobile devices
> Contemporary distributed computing technologies
 In this session we will consider
> Issues that must be addressed in developing mobile applications
> Using distributed technologies from mobile applications

3. Mobile Device and Application
Characteristics
 Mobile application developers face three key challenges
> Resource constrained devices
­Battery
powered, limited memory, low-power CPU, etc
> Different user interface technologies / metaphors
­Limited
screen sizes, no keyboard, pen input, etc
­Capability
to enter and manage small amounts of information in short sessions
> Getting data to / from the application
­Data
sources often in network
­Network
not always available when required
­When
is data transferred to / from the device?

4. What do Users Want?
 Users want simple, responsive, task-oriented applications which
> Allow them to perform quick, specific tasks while they are away from their
desktop PCs
> Have simple and direct graphical user interface
> Provide feedback
> Automate as much as possible
 Users do not want to
>Wait!
> Guess at what the application may or may not be doing
> Spend time searching for menus / controls / information
> Continually reconfigure the device in response to changing (network) environment

5. Common User Tasks
 Mobile device, particularly PDA, users want to be
able to
>Communicate with others instantly.
>Manage e-mail, events, appointments, and notifications.
>Access and share personal and business information
>Play games and access media files.
>Customize the interface to suit personal tastes

6. Putting the User in Control
 Users value and feel more comfortable with products
they can control
 Applications should put users in control by
>Allowing users to complete tasks in different ways but with
fewer steps
­e.
g. Pocket PC Contacts application
>Provide ways for users to customize the application
>Provide the opportunity to reverse or continue actions
despite non-critical errors

7. User Interfaces
 Mobile devices user interfaces are drastically different to
desktop user interfaces
 What are the key user interface issues we should be aware of?
> No keyboard, Input is by stylus
­Entering
text is difficult
­User
accuracy, parallax errors, etc
> User does not want to wade through many forms / controls to achieve their task
 What principles should guide the design of mobile application
user interfaces?
> Simplicity of use
> Make common tasks easy
> Consistency – within application and with desktop

8. User Interface Design
Guidelines
 A good user interface should
> Show only relevant data
> Show only the most important controls directly on the interface
> Make controls easy to
­distinguish
and interpret
­find
­use
> Make controls
­predictable
­consistent
– within the application & with desktop apps
> Use standard controls (e.g. Soft Input Panel)
> Leave space between controls to avoid accidental selections

9. Menus in User Interfaces
 Menus can be very useful
> Use menus to organize related groups of functions
> Organize menu items in a similar order to desktop applications
> Include only necessary items in the menu
> Limit number of items in menus to help users find items they need more quickly
> Arrange items order of frequency of use in context-sensitive menus
> Avoid deep menu hierarchies
 Put frequently used actions directly on the menu bar
> reduces user time and effort needed to find the item

10. Network Connectivity
 Many mobile applications use data retrieved from other sources (e.g. desktop machine,
networked servers)
 This data needs to be moved to / from the mobile device via
> Cable connection when sync’d to a desktop machine
> Wireless network connection
 Wireless networking offers easiest route for data transfer but
> Network is not always available – intermittent connections
­How
does application cope when network connection disappears?
> Process of connecting to / disconnecting from the network should be automatic and not require user
involvement
> Application should still operate responsively when network is unavailable
 Caching may be required to store the data needed to support the application when the
device is disconnected
> When to synchronize cached data with networked sources?
 Good design practices can make the state of connectedness transparent to the user

11. User Interface and
Connectivity
 Users often need to know whether they are connected to
the network or not
> provide this information to the user in a non-invasive way
> e.g. Pocket PC Bluetooth connection indicator
 The movement between connected and disconnected
state should be clear but not disruptive to normal
application operation
> avoid displaying dialog boxes when connections are established
and lost
 Give considerable thought to how your the interface
will behave when a connection is unexpectedly dropped

12. Security and Trust
 Users must be able to trust mobile devices and applications with their
personal information. This requires
 Availablity
> Personal information must always be available
 Security
> Personal information stored on the device must only be used or modified in appropriate ways
> Users should be offered security measures to help them protect their information.
 Privacy
> Stored personal information must be under the user’s complete control
> Device must provide ways for users to guard against unauthorized access
> Users must have full control over information removed from and downloaded to the device

13. Mobile Application
Design Principles
 Optimize for 80 percent of the cases; support the remaining 20 percent.
 Use audio for User Interface feedback, not as a novelty
 Reduce redundancy; promote one way to do things
 Let the user "learn once, do everywhere"
 Design for performance
 Place frequently needed controls at the top of the dialog box
 Show the most important information in the main view of the
application. The rest of the information should be one step away.

14. Pocket PC Design Principles
 Emphasize data and content
 The title bar caption should contain the name of the
application, not the current dialog box context
 Only prompt for user confirmation on actions that
cannot be undone
 Menus should be structured by logical groupings
 Apply ergonomic principles to the placement of
controls and information:
- Stylus-accessible controls should be 5 mm square
on the screen

15. SmartPhone Design
Principles
 Menus should be structured by logical groupings
 The left soft key:
> Always displays the most likely user task
> Is the Done soft key that closes the window, when needed
 The right soft key:
> Displays the Menu soft key when there is a menu
­Command
represented by the left soft key should be on the menu
> Should display the second most likely user task if there is no menu
> Is blank if not needed
> Is the Cancel key any time state can be saved
 Do not use "..." after any menu items.
 Full-screen message boxes can have only two options (one for each
soft key). For example, you cannot have Yes, No, Cancel.

16. Summary
 In this session we have discussed
> Mobile device characteristics and limitations
> Guidelines for developing mobile applications

17. Reading and Resources
Reading
 Wigley & Wheelwright, Microsoft .NET Compact Framework Core Reference,
Microsoft Press, 2003
Resources
 Pocket PC User Interface Guidelines,
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/ui_guide_ppc/htm/_UIguide_start. How to Maintain a Single Binary for Pocket PC and Smartphone,
http://msdn.microsoft.com/library/en-us/dnppcgen/html/mantsngbin.asp?frame=true
 Use Threading with Asynchronous Web Services in .NET Compact Framework to
Improve User Experience, http://msdn.microsoft.com/library/default.asp?url
=/library/en-us/dnppcgen/html/use_thread_async_web_services.asp