.NET Mobile Application Development Designing Mobile Applications

1
.NET Mobile Application DevelopmentDesigning
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

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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

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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

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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 syncd 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

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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
  users 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

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Mobile ApplicationDesign 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.

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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
• Information should flow top-down, left-right
• Keep all editable controls above the soft input
  panel (SIP) region
• Standardize on a 4 4 metric
• The origin of a control always maps to a
  four-pixel increment
• All controls maintain a four-pixel gutter between
  themselves
• Reduce the number of unlabeled or complex icons
  use text to define features
• The Options dialog and Settings control panel do
  not have menus
• The content of a tab does not scroll

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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.

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Summary

• In this session we have discussed
• Mobile device characteristics and limitations
• Guidelines for developing mobile applications

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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.asp
  
• How to Maintain a Single Binary for Pocket PC and
  Smartphone, http//msdn.microsoft.com/library/en-u
  s/dnppcgen/html/mantsngbin.asp?frametrue
• Use Threading with Asynchronous Web Services in
  .NET Compact Framework to Improve User
  Experience, http//msdn.microsoft.com/library/defa
  ult.asp?url/library/en-us/dnppcgen/html/use_threa
  d_async_web_services.asp