Windows Phone Platform Overview A different kind of phone, designed for a life in motion

WINDOWS PHONE HARDWARE

Topics Windows Phone hardware examined

Processor and operating system Graphical Display Touch input Location sensors Camera Memory Network

The Windows Phone Device

The Windows Phone is a pretty powerful device

Best regarded as a computer that can make phone calls

Runs an operating system specially optimised for mobile devices

Windows Phone processor speed The Windows phone hardware standard requires

that a Windows Phone device will have a processor “clock speed” of at least 1 GHz

This means that something will go “tick” inside the phone 1,000,000,000 times a second A tick lasts a nanosecond, the time it takes light

to travel around 30 cm

Processors and Clocks Each time the clock in a Central Processor

Unit (CPU) goes “tick” a particular low-level operation will be performed Perform part of a hardware instruction Load data from memory Store data into memory

The faster the clock ticks, the faster the processor is running

Clocks and speeds A Windows PC processor runs at 2-4 GHz, a A Windows Phone processors start at 1 GHz

This does not mean a phone is around half the speed of a desktop PC

The clock speed is just one factor that determines computer speed A bit like engine size in a car

Speed and processors Some processors need more “ticks” to perform the

same action Phones use “Reduced Instruction Set Computing”

designs which reduce the amount they can do per clock tick

The desktop PC may contain multiple processors The Windows Phone cannot run at full speed all the

time as this would flatten the battery

Performance and programs When you write a Windows Phone application you

have to worry about performance There is not the spare processing power available

to compensate for poor programming techniques Performance must be considered at all times

This will turn us into better programmers The techniques we are going to learn will

improve all the programs we write

Windows Phone Operating System

Windows Phone 7 is not based on the Windows 7 operating system The numbering is coincidental

Windows Phone is actually based on Windows Compact Edition (Windows CE) This is an operating system specially built for use

in battery operated devices with low power processors

Operating Systems and Programs From the point of view of a programmer the

operating system is becoming less important We are going to write Silverlight and XNA

applications that make method calls to use the underlying system

How that underlying system works does not affect our programs directly They can run on any platform

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Windows Phone Graphical Display The Windows Phone has a high resolution display

with at least 800x480 pixel resolution This makes a lot of work for the hardware

The higher the resolution of the display the more work needed to keep it up to date

The display can be used in landscape and portrait mode The phone will detect how it is being held and a

program can change the display to match

Graphics Hardware Acceleration Desktop PCs have used graphical acceleration for a

long time The Graphical Processing Unit (GPU) draws the

display and performs image processing on it GPUs are now appearing in mobile phones The Windows Phone contains a GPU

Used to render user Silverlight user interfaces Also used to create 3D games in XNA

Touch Input Modern mobile devices are making

increasing use of touch screens These are now provided in addition to a

keyboard The Windows Phone user interface is

entirely touch based, using a capacitive multi-touch input device

Resistive Touch Input Screens Early mobile devices used resistive touch screens

Touching the screen connects two plastic membranes to form a circuit

The resistance across this circuit is used to work out the location of the touch

This technology is very precise (particularly if a stylus is used) But it cannot easily detect more than one touch

Capacitive Touch Input Capacitive touch sensors detect the change in

capacitance caused by touch event There is no physical movement The touch sensor can be printed on a glass

screen The resolution of a capacitive screen is not as great

as a resistive one This is not a problem as the user will be touching

with a finger, not a stylus A capacitive screen can track multiple touches

Touch and Gestures Gestures are particular movements made

with one or more finger Dragging an item on the screen Pinching movements to zoom in and out

The Windows Phone operating system has built in support for gesture input A program can be sent a message when

a user has performed a particular gesture

Location Support A Windows Phone contains a Global

Positioning System (GPS) receiver Works well when outdoors with a view of

the sky The phone will also other location

information Location of cellphone towers in use Location of WiFi access point

This “assisted” positioning makes it possible to determine position when inside buildings

Accelerometer The accelerometer can measure acceleration in

three directions (X, Y and Z) This can be used to detect movement of the phone It can also be used to determine how the phone is

being held This orientation information can be used to

control games by tipping the phone

Camera The camera will be at least 5Megapixels

This makes for good quality pictures The pictures which are taken are stored within the

phone and transferred to the Windows PC using the Zune software

Programs can load these pictures, and other pictures from the media in the phone Your programs can also initiate a photograph

Camera Limitations Our programs can’t read a live video feed from the

camera in this Windows Phone release This is not a hardware limitation

Our programs can’t take a picture without user involvement This is to stop the creation of “spyware”

applications that take pictures without user consent

Hardware Buttons All Windows Phones have a specific set of physical

buttons Start, Back, Lock, Search, Camera, Volume

These will work in exactly the same way on every version of the phone

Programs are required to use them in a particular way too

Start Button Starts a new program When the user presses Start they are always

taken to the start menu to choose a program to run

The application that was running when Start was pressed is removed from memory

This is part of the way that Windows Phone enforces the “one program at a time” rule

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Back button This button has several uses

Within a particular program it moves you back to the previous menu

When at the top level menu of a program it is used to exit the program and return to the Start menu

At the Start menu the back button will return the user to the program they were running when they pressed Start to do something new

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The Back button and the Phone UI Back is rather hard to explain

But very easy for users to get to grips with It makes it easy to drop in and out of applications

on the phone without having to keep finding them and restarting them

For us developers it means that programs may be “woken up” from having been stopped

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Other Buttons Lock Button

Stops the currently running program and locks the phone

Search Starts a search operation. Your program should

respond to search appropriately Camera

Stop the current program and take a picture

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Phone Keyboard Some Windows Phone devices will be fitted with

hardware keyboards The system provides a “software” keyboard that

uses the touch screen When we design our programs we need to make

sure that they can be used with or without a physical keyboard

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Phone Memory There are two flavours of memory Main memory

This is where programs are loaded and executed Fast memory chips connected directly to the

processor Mass storage memory

This is where program, data and media are stored

Slower storage that holds its data when the power is turned off

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Main Memory A Windows Phone will have at least 256Mbytes of

main memory A few years ago this was a huge amount, but

these days it is not quite as impressive It can soon get eaten up by programs that use a

lot of graphics in their user interfaces In contrast a desktop PC will have around 8 times

that memory space, with at least 2Gbytes of RAM

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Mass Storage A Windows Phone will have at least 8Gbytes of

mass storage In program terms this is a lot, but most of it will be

used store media A single music track is around 8 Mbytes A high quality picture is around 2 Mbytes An hour of good quality video is around 1Gbyte

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Network Windows Phones have lots of connectivity options:

WiFi wireless network (high speed) 3G phone network (high to media speed) GPRS phone network (low speed) Out of coverage (no speed)

Software on a mobile device must deal with all these types of network

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Programming Considerations A Windows Phone is an amazing device

But it is limited by size and battery power Users will expect a high quality experience

This will be based on their experience on much more powerful devices which are not mobile

Our job as developers is to make the most of what the platform gives us This gives us more to think about when we write

our programs

The Good News Programming for a phone is fun! The range of features a device has, and the fact it is

mobile makes it possible to invent completely new applications

The development environment is really powerful and easy to use

You get a lot of help from the system in creating great user interfaces

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Review Windows Phone is a computer, but one working

specifically in the mobile environment All Windows Phone devices are built to a particular

standard with standard features Performance and storage is restricted and our

program design must reflect this Network connectivity is variable on a phone Programming a phone is harder than a desktop, but

still fun

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WINDOWS PHONE ECOSYSTEM

Topics The ecosystem that surrounds the Windows Phone

device Zune media management and connection Windows Live and Xbox Live and Windows Phone Bing search and Windows Phone Bing Maps and Windows Phone Windows Phone Notification Services

Windows Phone Ecosystem A Windows Phone device is surrounded by other

services which provide an “ecosystem” These services bind to software in the phone device We can write software that makes use of these

services to create brand new solutions In this section we are going to take a look at the

services and consider how we might use them

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Zune Software

The Zune software provides the link between the Windows Phone and the PC

It allows media to be synchronised with the phone

It also provides the link to the device for development with Visual Studio

Windows Live and Xbox Live A Windows Phone owner can

register their phone with Xbox Live

This will also connect them with their Xbox Gamertag if they have one

Games can use the gamertag to manage achievements and high scores

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Bing Maps Programs in the phone can

request maps from the Bing service

There is also a Silverlight control you can add to your programs to view and navigate the map

You can also make searches for items near your position

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Windows Notification Service It is often the case that external systems need to

send a message to a program in a phone Tell you that your dry cleaning is ready Challenge a gamer to a duel

Applications register with the Windows Phone notification service and servers can then use this to send messages to the phone user

These are buffered if the phone is not connected when the message is sent

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Creating a service of your own There is no reason why you can’t create your own

network based service for a Windows Phone client to use You need to write the server application too

You can write both ends of the service in C# and you could host the service in the Windows Azure cloud

Students can get free access to some cloud services

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Review A mobile phone is now a connected component of a

much larger “ecosystem” A Windows Phone can use several of these

Zune PC connection and media synchronisation Windows Live and Xbox Live Bing Maps Windows Notification Service

Your programs can use these elements to make brand new connected applications

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WINDOWS PHONE PROGRAM EXECUTION

Topics The Windows Phone Operating System Multi-tasking on Windows Phone Windows Phone and Managed Code Just in Time compilation Program “sandboxes” and Managed Code Developer Implications

The Windows Phone Operating System

Windows Phone 7 does not use Windows 7 as an operating system The fact they have the same number is

just a coincidence Windows Phone instead uses an operating

system called Windows CE This is specially designed for use on small,

battery powered, devices

Multi-Tasking Multi-tasking means running multiple programs at

once Windows PCs let you do this

You can have IE and Word both running at once Unfortunately multi-tasking places heavy demands

on the processor and uses a lot of memory Therefore the first version of Windows Phone does

not provide multi-tasking

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Missing Multi-Tasking A mobile device does not really have a screen large

enough to view two programs at once The phone has been designed to make it as easy as

possible to switch between programs Must users want task switching rather than multi-

tasking The operating system itself can multi-task

The music player and email programs can both run at the same time as user programs

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Programs on Windows Phone Programs for Windows Phone are written in

.NET and run within a Managed Code environment on the device

The phone performs Just in Time compilation of the intermediate language (Microsoft Intermediate Language – MSIL)

The programs that run are assemblies that are signed by the developer This is used to prove where the code

came from

Microsoft .NET .NET is the name for an architecture from Microsoft

that runs programs It includes standards for the following:

Design of MSIL and program file format Data types System libraries C# programming language VB .NET programming language

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The Microsoft Intermediate Language

The Microsoft Intermediate Language (MSIL) is a half way house between a high level language and machine code

It is designed to be easy to translate into machine code

The phone can run MSIL from any .NET compiler C#, Visual Basic, F#, IronPython, IronRuby, C++

The user interface code must be C#

Running .NET Assemblies When a .NET program needs to run something has

to convert the intermediate language into real machine code for the target processor

This happens in the instant before the program actually runs

It is called “Just In Time” compilation

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Just in Time Compilation

Target hardware Windows PC Xbox Windows Phone

C# source file

C# compiler

Assembly file

containing MSIL

Just In Time

compiler

Machine code in

memory

Visual Studio

Development

Environment

Just in Time Compilation

Target hardware Windows PC Xbox Windows Phone

C# source file

C# compiler

Assembly file

containing MSIL

Just In Time

compiler

Machine code in

memory

Visual Studio

Development

Environment

Programmer writes the

program

Just in Time Compilation

Target hardware Windows PC Xbox Windows Phone

C# source file

C# compiler

Assembly file

containing MSIL

Just In Time

compiler

Machine code in

memory

Visual Studio

Development

Environment

Visual Studio compiles the

source

Just in Time Compilation

Target hardware Windows PC Xbox Windows Phone

C# source file

C# compiler

Assembly file

containing MSIL

Just In Time

compiler

Machine code in

memory

Visual Studio

Development

Environment

The assembly file is

transferred to the target

Just in Time Compilation

Target hardware Windows PC Xbox Windows Phone

C# source file

C# compiler

Assembly file

containing MSIL

Just In Time

compiler

Machine code in

memory

Visual Studio

Development

Environment

When the program runs the Just In

Time compiler converts the MSIL

into binary

Just in Time Compilation

Target hardware Windows PC Xbox Windows Phone

C# source file

C# compiler

Assembly file

containing MSIL

Just In Time

compiler

Machine code in

memory

Visual Studio

Development

Environment

The machine code runs

inside the target

Intermediate Language Good things about intermediate languages

Can run on a range of platforms Can use lots of different programming

languages (as long as they compile down to MSIL)

Programs are smaller than machine code

Programs can be digitally signed and verified

Bad things about intermediate languages The need to Just In Time (JIT) compile

them slows down program execution

Managed Code When your program runs on Windows Phone it

actually runs in a “managed” environment This means that what it does is validated before the

program is allowed to do it Array subscripts are checked Program not allowed to attempt to control

hardware directly This stops the phone from being affected by a

rogue application

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Review The built-in programs inside the phone can multi-

task but only one application can run at a time in the phone

The phone users the .NET Microsoft Intermediate Language for applications

These are “Just in Time” compiled when they are started and run inside a managed shell

This trades raw speed for safety and portability

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WINDOWS PHONE APPLICATION DEVELOPMENT

Topics Writing programs for Windows Phone The Windows Phone emulator Using the Windows Phone features from software Silverlight and XNA program development Development tools Windows Phone Marketplace

Windows Phone Programming Writing programs for Windows Phone is the same as

writing for any .NET platform Edit, compile and debug within Visual Studio

But you need to remember you are writing for a platform a bit more constrained than a PC

You can incorporate .third party NET libraries (assemblies) into your applications

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Windows Phone Emulator The emulator runs on your PC It contains exactly the same code as

the real phone, but compiled for the Windows PC

It lets you see what your programs look like and whether they work correctly It does not show you what the

application performance will be like on a real device

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Using Windows Phone from software

Windows Phone provides a library of “Launchers” and “Choosers” that your programs can invoke Launchers start other tasks in the phone

Start a phone call

Choosers allow the user to select an option and then restart your program so it can use the returned value

Select a contact from the Address Book

Network Connectivity A Windows Phone will be able to use the

3G phone network and WIFI to connect to the internet

Your programs will be able to interact with servers, call web services and engage in REST sessions

In the present version of the operating system there is no support for direct socket connections

Silverlight and XNA applications You can build two kinds of applications for

a Windows Phone Silverlight

Business applications and simple casual games

XNA XNA is a game development

environment with support for 2D and 3D games with hardware accelerated graphics

Silverlight Applications This is not a very good looking

Silverlight application But it does show that you

can build displays for user applications using Silverlight

There are lots of custom display components for the phone that you can use

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XNA Applications XNA is a game development

environment for Windows PC, Xbox and now Windows Phone

Existing XNA games are very easy to move onto the phone

The phone provides 3D graphics support for games Built in shaders

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Creating an Application You select the type of your application (XNA or

Silverlight) when you create the new project in Visual Studio

It is not possible to create a single program that uses both technologies

There is no technical reason why you could not create a Silverlight game or an XNA business application

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Development Tools The Development Tools for the platform are a free

download They tools provide a version of Visual Studio and

the Windows Phone emulator These will also integrate into an existing Visual

Studio installation You can also obtain free versions of the Expression

Blend user interface design tools for Silverlight

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Windows Phone Marketplace You can develop and test your application on the

emulator for free To sell your application or deploy it to a real device

you must register as a developer This costs $99 per year Students can become developers for free via

Microsoft DreamSpark

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Marketplace Rules In a year of your subscription you can publish any

number of “paid” applications and up to 5 free ones To distribute more free applications costs $20 per

application When you sell an application you get 70% of the

price you charge You can distribute “demo” and “time trialed”

versions of your application

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Marketplace approval A program submitted for sale via marketplace is

submitted to an approvals process This includes checks for matters of taste and

decency, along with proper application behaviour If the program fails the process you will be given a

report and can re-submit the application

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Review Windows Phone programs are developed in the

same way as any other .NET application The Windows Phone emulator does not emulate the

speed of the platform Programs can make use of phone functions Windows Phone programs either Silverlight

(business) or XNA (game) based The development tools are all free You need to join the marketplace to sell apps