CFInterop

04/08/23

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Compact Framework InteropCompact Framework Interop

Douglas BolingPresidentBoling Consulting [email protected]

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About MeAbout Me

Independent Windows CE consultant Independent Windows CE consultant Microsoft Embedded MVPMicrosoft Embedded MVP

WriterWriter Author of “Programming Windows CE”Author of “Programming Windows CE” Various articlesVarious articles

Windows CE InstructionWindows CE Instruction Windows CE Application DevelopmentWindows CE Application Development Windows CE OAL and DriversWindows CE OAL and Drivers .NET Compact Framework.NET Compact Framework

www.bolingconsulting.comwww.bolingconsulting.com

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AgendaAgenda

Quick intro to the Compact FrameworkQuick intro to the Compact Framework

What is Interop?What is Interop?

P/Invoke BasicsP/Invoke Basics

Marshalling Marshalling

Calling native DLLsCalling native DLLs

Notifications from outsideNotifications from outside

What’s coming in Version 2.0What’s coming in Version 2.0

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Integration ImperativeIntegration Imperative

ClientClient

Web Web ApplicationsApplications

PartnerPartnerPartnerPartner

Credit Credit infoinfo

Ad-hocAd-hoc

ScreenScreenscrapescrape

Email

Email

FAXFAX

B2CB2Cwebsitewebsite

HTMLHTML

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Integration ImperativeIntegration Imperative

ClientClient

WebsiteWebsite

HTMLHTML

Screen

Scrape

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Windows XP EmbeddedWindows XP EmbeddedThe most complete embedded platform enabling advanced The most complete embedded platform enabling advanced devices by delivering the power of Windows in devices by delivering the power of Windows in componentized formcomponentized form

Windows CE Windows CE Windows CE integrates reliable real time capabilities with Windows CE integrates reliable real time capabilities with advanced Windows technologies to rapidly build a wide advanced Windows technologies to rapidly build a wide range of innovative, small-footprint devicesrange of innovative, small-footprint devices

Windows Embedded PlatformsWindows Embedded Platforms

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.NET on Embedded Devices.NET on Embedded Devices

Windows XP EmbeddedWindows XP Embedded Full v1.0 .NET runtimeFull v1.0 .NET runtime

1.1 in SP21.1 in SP2 Total compatibilityTotal compatibility

Windows CE .NETWindows CE .NET Specially designed runtimeSpecially designed runtime Smaller foot printSmaller foot print Tuned for low memory, low power devicesTuned for low memory, low power devices Limited to two languagesLimited to two languages

C#, Visual Basic .NETC#, Visual Basic .NET

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In short: .NET runtime for small devicesIn short: .NET runtime for small devices CLR + subset of FCLCLR + subset of FCL

1.0 supports1.0 supports Pocket PC 2000, 2002Pocket PC 2000, 2002 Windows Mobile 2003Windows Mobile 2003

Pocket PC and SmartphonePocket PC and Smartphone

Windows CE .NET 4.1 and laterWindows CE .NET 4.1 and later

2.0 supports2.0 supports Windows Mobile 2003 for Pocket PC onlyWindows Mobile 2003 for Pocket PC only Windows CE 5.0 and laterWindows CE 5.0 and later

.NET Compact Framework.NET Compact Framework

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Get the Latest Stuff!Get the Latest Stuff!

Two service packs have been releasedTwo service packs have been released

Service Pack 1Service Pack 1 Bug fixesBug fixes

Service Pack 2Service Pack 2 Minor class library additionsMinor class library additions Performance improvementsPerformance improvements Bug fixesBug fixes

Version 2.0 in Whidbey betaVersion 2.0 in Whidbey beta

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CF SimilaritiesCF Similarities

Same type safe executionSame type safe execution No uninitialized variablesNo uninitialized variables No unsafe castsNo unsafe casts No bad array indexingNo bad array indexing No bad pointer mathNo bad pointer math

Similar garbage collectionSimilar garbage collection No ref countingNo ref counting No leaksNo leaks

JIT compilation JIT compilation Compiled code kept in memoryCompiled code kept in memory Pitched in low memory situationsPitched in low memory situations

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CF SimilaritiesCF Similarities

Exceptions for error handlingExceptions for error handling

Language neutral type systemLanguage neutral type system Common scheme across all managed codeCommon scheme across all managed code

Use of assembliesUse of assemblies

PE file formatPE file format

Mutithread supportMutithread support

Windows Forms supportWindows Forms support

Can consume web servicesCan consume web services

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CF Difference StrategyCF Difference Strategy

V1 support for client processingV1 support for client processing Little support for devices as serversLittle support for devices as servers

Reduced resources on embedded devicesReduced resources on embedded devices Less CPU power/system memory renders some .NET features Less CPU power/system memory renders some .NET features

impracticalimpractical

CF Development scheduleCF Development schedule They had to ship!They had to ship!

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CF DifferencesCF Differences

No COM interop supportNo COM interop support Use P/Invoke to call unmanaged functionsUse P/Invoke to call unmanaged functions Manually create managed class that P/Invokes to DLL that then Manually create managed class that P/Invokes to DLL that then

calls COM interfacescalls COM interfaces

No remoting No remoting Client web services supportedClient web services supported

No ASP .NETNo ASP .NET

No generic serializationNo generic serialization

No install time compilationNo install time compilation No nGenNo nGen

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CF DifferencesCF Differences

No reflection emitNo reflection emit

Domain neutral code areas not supportedDomain neutral code areas not supported

Asynchronous delegates not supported Asynchronous delegates not supported

File change notifications not supportedFile change notifications not supported

No XML schema validationNo XML schema validation

No XML xpath queriesNo XML xpath queries

FCL SubsetFCL Subset

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Other ChangesOther Changes

.NET CF Class library about 25% of desktop class library.NET CF Class library about 25% of desktop class library

Runtime tuned for embedded systemsRuntime tuned for embedded systems Low memory devicesLow memory devices Low power CPUsLow power CPUs

Extra classes addedExtra classes added IrDA classesIrDA classes SQLCE classesSQLCE classes Pocket PC control supportPocket PC control support MessageWindow classMessageWindow class

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.NET CF Size.NET CF Size

Approximately 1.3 Mbytes on Pocket PC (ARM)Approximately 1.3 Mbytes on Pocket PC (ARM)

Needs approximately 1 Meg of RAMNeeds approximately 1 Meg of RAM

Application sizes quite smallApplication sizes quite small 5 – 100k5 – 100k

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.NET Framework.NET FrameworkSystem.WebSystem.Web System.Windows.FormsSystem.Windows.Forms

System.DrawingSystem.Drawing

System.XMLSystem.XMLSystem.DataSystem.Data

SystemSystem

ServicesDescriptionDiscoveryProtocols

UIHTML ControlsWeb Controls

Security

Session StateConfiguration

Cache

SQL Client

SQL ServerCEDesign

ADO.NET

IO

Net

Collections

Security

Reflection

Resources

Text

Globalization

Configuration

Service Process

Diagnostics

Threading

RuntimeInterop ServicesRemotingSerialization

Design

Drawing 2D

Imaging

XML Document

Xslt/XPath

Serialization

Reader/Writers

Printing

Text

Component Model

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.NET Compact Framework.NET Compact FrameworkSystem.WebSystem.Web System.Windows.FormsSystem.Windows.Forms

System.DrawingSystem.Drawing

System.XMLSystem.XMLSystem.DataSystem.Data

SystemSystem

ServicesDescriptionDiscoveryProtocols

UIHTML ControlsWeb Controls

Security

Session StateConfiguration

Cache

SQL Client

SQL ServerCEDesign

ADO.NET

IO

Net

Collections

Security

Reflection

Resources

Text

Globalization

Configuration

Service Process

Diagnostics

Threading

RuntimeInterop ServicesRemotingSerialization

Design

Drawing 2D

Imaging

XML Document

Xslt/XPath

Serialization

Reader/Writers

Printing

Text

Component Model

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.NET CF Interop.NET CF Interop

Why important?Why important? The v1 release of .NET Compact Framework will not support The v1 release of .NET Compact Framework will not support

everything necessary for a Windows CE applicationeverything necessary for a Windows CE application

Even if it did, embedded devices frequently need to be closer to Even if it did, embedded devices frequently need to be closer to the hardware than PC applicationsthe hardware than PC applications

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General Strategy General Strategy

Enable developers to provide their own solutionsEnable developers to provide their own solutions Decent P/Invoke supportDecent P/Invoke support COM ready managed threadsCOM ready managed threads

Basic support for notifying managed code of external eventsBasic support for notifying managed code of external events Somewhat of an afterthoughtSomewhat of an afterthought

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General ArchitectureGeneral Architecture

Managed applications are managed as Windows CE processesManaged applications are managed as Windows CE processes Subject to the same limitations of a Windows CE processSubject to the same limitations of a Windows CE process

32/64 Meg memory space32/64 Meg memory space DLL issues in Pocket PC 2002DLL issues in Pocket PC 2002

Native DLLs are loaded into the process space of the managed Native DLLs are loaded into the process space of the managed applicationapplication

Unmanaged DLLs not loaded until called Unmanaged DLLs not loaded until called Call your unmanaged DLLs earlyCall your unmanaged DLLs early

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What is SupportedWhat is Supported

Supported Supported Calling unmanaged functions in DLLsCalling unmanaged functions in DLLs

““P/Invoke” supportP/Invoke” support

UnsupportedUnsupported Directly calling COM interfacesDirectly calling COM interfaces

Only by calling unmanaged DLLs that deal with COM Only by calling unmanaged DLLs that deal with COM objectsobjects

ActiveX controlsActiveX controls Third party solution availableThird party solution available

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Steps for Calling Native CodeSteps for Calling Native Code

Decide what you need to doDecide what you need to do

Look for a managed wayLook for a managed way Always choose the managed way before P/InvokeAlways choose the managed way before P/Invoke

Look in the SDK for the unmanaged callLook in the SDK for the unmanaged call Yes, you’ll still need to know the APIYes, you’ll still need to know the API

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Create managed class to wrap P/Invoke callsCreate managed class to wrap P/Invoke calls

Declare an static, extern function with matching call Declare an static, extern function with matching call parametersparameters

Declare function as externalDeclare function as external C# – Mark with the DllImport attributeC# – Mark with the DllImport attribute VB .NET – Use Lib keywordVB .NET – Use Lib keyword

Create public methods that call P/Invoke methodsCreate public methods that call P/Invoke methods

Steps for Calling Native CodeSteps for Calling Native Code

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Two General PossibilitiesTwo General Possibilities

Call Win32 API directlyCall Win32 API directly SimplestSimplest Doesn’t require native DLLDoesn’t require native DLL Limited marshalling supportLimited marshalling support

Calling native DLLCalling native DLL Enables custom marshallingEnables custom marshalling Native DLL can Native DLL can

Call APIs with complex argumentsCall APIs with complex arguments Call COM interfacesCall COM interfaces

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Calling Win32 FunctionsCalling Win32 Functions

Finding the APIFinding the API

Declaring the APIDeclaring the API

Calling the APICalling the API

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Finding the Win32 FunctionFinding the Win32 Function

Understand the difference between the Pocket PC and an Understand the difference between the Pocket PC and an embedded Windows CE deviceembedded Windows CE device

Pocket PCs are based on Windows CEPocket PCs are based on Windows CE Contain some unique APIsContain some unique APIs Don’t support every single Windows CE APIDon’t support every single Windows CE API

Embedded Windows CE devices can have different APIsEmbedded Windows CE devices can have different APIs Check the specific SDK for that deviceCheck the specific SDK for that device

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Declaring External FunctionsDeclaring External Functions

Function to call should be declared with matching Function to call should be declared with matching parametersparameters

Function must be marked Function must be marked ““static” and “extern” in C#static” and “extern” in C# DllImport attributeDllImport attribute

[DllImport(“coredll.dll")]public static extern unsigned int GetTickCount ();

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External Functions in VBExternal Functions in VB

VB .NET function declarationVB .NET function declaration Use Lib keyword to declare external functionUse Lib keyword to declare external function

Declare Function GetTickCount Lib "coredll.dll" () _As Integer

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External Function PrototypesExternal Function Prototypes

Check documentation Check documentation Pocket PC 2000 and 2002Pocket PC 2000 and 2002

Need Embedded Visual C++ 3.0Need Embedded Visual C++ 3.0 Windows Mobile 2003Windows Mobile 2003

Need Embedded Visual C++ 4.0Need Embedded Visual C++ 4.0

Look in .h files in SDKLook in .h files in SDK SDKs available on Microsoft’s web siteSDKs available on Microsoft’s web site

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Which DLL?Which DLL?

Windows CE API DLL is Windows CE API DLL is COREDLL.DLLCOREDLL.DLL Almost everything is hereAlmost everything is here

Some other DLLs are usedSome other DLLs are used AYGShell.dll – Pocket PC shell functionsAYGShell.dll – Pocket PC shell functions CommCtrl.dll – Common control libCommCtrl.dll – Common control lib WinSock.dll – Windows SocketsWinSock.dll – Windows Sockets Phone.dll – High level phone controlPhone.dll – High level phone control SMS.dll – SMS messaging APISMS.dll – SMS messaging API

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Using DllImportUsing DllImport

DllImport attribute class parametersDllImport attribute class parameters EntryPoint – Specifies different native function nameEntryPoint – Specifies different native function name SetLastError – Maintains last error valueSetLastError – Maintains last error value

[DllImport ("\\windows\\UnManaged.dll", EntryPoint="TestProcW", SetLastError=true)]

public static extern int TestProc (int a, byte[] b);

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At RuntimeAt Runtime

Calling function causes the CLR:Calling function causes the CLR: Load the DLL using LoadLibraryLoad the DLL using LoadLibrary Use GetProcAddress to get entry pointUse GetProcAddress to get entry point Call the functionCall the function

Problems resolving the function results in Problems resolving the function results in MissingMethodException in managed applicationMissingMethodException in managed application

Unhandled exceptions in the unmanaged code results in app Unhandled exceptions in the unmanaged code results in app termination termination

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Tips for using P/InvokeTips for using P/Invoke

Isolate P/Invoke calls to custom classesIsolate P/Invoke calls to custom classes

Make P/Invoke functions privateMake P/Invoke functions private

Public functions call P/Invoke functions in try / catch wrapperPublic functions call P/Invoke functions in try / catch wrapper This also allows parameter checking and necessary marshaling This also allows parameter checking and necessary marshaling

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Data MarshalingData Marshaling

Simple TypesSimple Types Direct TranslationDirect Translation

Simple Objects and ValueTypesSimple Objects and ValueTypes Objects that contain simple typesObjects that contain simple types Execution engine points at the data of the objectExecution engine points at the data of the object Some exceptionsSome exceptions

Complex Objects and Value TypesComplex Objects and Value Types Objects containing other objects need to manually marshal dataObjects containing other objects need to manually marshal data

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Marshaling DifferencesMarshaling Differences

Objects marshaled only one level deepObjects marshaled only one level deep Objects that contain objects must be manually marshaledObjects that contain objects must be manually marshaled

Datatypes are marshaled according to typeDatatypes are marshaled according to type MarshalAs attribute is not supportedMarshalAs attribute is not supported

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Marshaling Differences 2Marshaling Differences 2

Object data is always laid out sequentiallyObject data is always laid out sequentially StructLayout attribute is not usedStructLayout attribute is not used Packing always set to 4Packing always set to 4

Floating point and 64-bit integer parameters need to be passed Floating point and 64-bit integer parameters need to be passed in as binary datain as binary data

Cannot use delegates with native codeCannot use delegates with native code

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Marshaling Of Simple TypesMarshaling Of Simple Types

The execution engine marshaling of simple data typesThe execution engine marshaling of simple data types

C#C# Visual BasicVisual Basic Native CodeNative Code

intint IntegerInteger int (32-bit integer)int (32-bit integer)

shortshort ShortShort short (16-bit)short (16-bit)

boolbool BooleanBoolean BYTE (8-bit)BYTE (8-bit)**

charchar CharChar wchar (16-bit)wchar (16-bit)

StringString StringString wchar *wchar *

Array Array

int []int []

ArrayArray

Integer ()Integer ()

Data of the ArrayData of the Array

int *int *

longlong LongLong Not Supported (64-bit)Not Supported (64-bit)

doubledouble DoubleDouble Not Supported (floating pont)Not Supported (floating pont)

*bool and Boolean do NOT always convert to a Win32 BOOL*bool and Boolean do NOT always convert to a Win32 BOOL

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Marshaling Simple ObjectsMarshaling Simple Objects

Parameter TypeParameter Type Marshaling ActionMarshaling Action

ArrayArray Point at the array dataPoint at the array data

String Builder*String Builder* Make a copy and point at the string data Make a copy and point at the string data (LPSTR)(LPSTR)

StringString Point at the string data Point at the string data (LPSTR)(LPSTR)

ByRef String*ByRef String* Make a copy of the string and point at the Make a copy of the string and point at the data data (LPSTR)(LPSTR)

Other objectsOther objects Point at the member dataPoint at the member data

*Execution Engine will resize managed strings after native function call*Execution Engine will resize managed strings after native function call

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public class Rect {

int left;int top;int right;int bottom;

}

Marshaling Simple ObjectsMarshaling Simple Objects

Classes are laid out sequentially Classes are laid out sequentially Packing always set to 4Packing always set to 4

Only classes containing simple types will be automatically Only classes containing simple types will be automatically marshaledmarshaled

Native Code - CC#

typedef struct _RECT {

LONG left; LONG top; LONG right; LONG bottom;

} RECT;

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Marshaling Complex ObjectsMarshaling Complex Objects

Marshal classMarshal class Located in System.Runtime.InteropServicesLocated in System.Runtime.InteropServices Provides advanced functionality to customize marshalingProvides advanced functionality to customize marshaling

Allows you to get copy managed objects into native codeAllows you to get copy managed objects into native code

Allows you to read and write raw memory if neededAllows you to read and write raw memory if needed

When all else fails use byte arrayWhen all else fails use byte array

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Classic P/Invoke AreasClassic P/Invoke Areas

The registry APIThe registry API

Interprocess communicationInterprocess communication

Managing very large memory blocksManaging very large memory blocks

Anything hardware relatedAnything hardware related

Anything with a COM InterfaceAnything with a COM Interface Obex, Pocket Outlook (POOM), … Obex, Pocket Outlook (POOM), …

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Writing Native DLLsWriting Native DLLs

Standard Windows CE dllStandard Windows CE dll

Created with Embedded Visual C++Created with Embedded Visual C++

CPU specificCPU specific Need a version for each CPU supportedNeed a version for each CPU supported

Beware C++ name manglingBeware C++ name mangling

Callable functions must be exported Callable functions must be exported

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Tips for Writing Native DLLsTips for Writing Native DLLs

Use Extern “C” Use Extern “C” Simplifies your exported function nameSimplifies your exported function name

Depends.exe and Dumpbin /Exports are your friendDepends.exe and Dumpbin /Exports are your friend

Test with a simple native applicationTest with a simple native application Make sure the DLL loads properlyMake sure the DLL loads properly Make sure the function is exposed as you expectedMake sure the function is exposed as you expected

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Limitations Limitations

Functions in DLLs should not block for long periods of timeFunctions in DLLs should not block for long periods of time

DLLs can’t call into managed codeDLLs can’t call into managed code Events must be signaled using window messagesEvents must be signaled using window messages

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Code ExampleCode Example

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External EventsExternal Events

How can a .NET CF application be notified of external How can a .NET CF application be notified of external events?events?

MessageWindow classMessageWindow class CF unique class for external event reportingCF unique class for external event reporting

Basically, it’s a window that exposes its WndProc to the Basically, it’s a window that exposes its WndProc to the managed codemanaged code

Helper methods to send/post messages to other windowsHelper methods to send/post messages to other windows

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MessageWindow ClassMessageWindow Class

Apps can send and receive window messagesApps can send and receive window messages

Messages have two 32 bit parametersMessages have two 32 bit parameters

No support for marshaling data pointed to by window No support for marshaling data pointed to by window parametersparameters

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MessageWindow ClassMessageWindow Class

SendMessageSendMessage Sends a messageSends a message

PostMessagePostMessage Posts a messagePosts a message

HwndHwnd Handle to native windowHandle to native window

WndProcWndProc Override to receive messages Override to receive messages sent to windowsent to window

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Using MessageWindowUsing MessageWindow

Derive class from MessageWindowDerive class from MessageWindow

Override the WndProc methodOverride the WndProc method

Interpret window messages as necessary eventsInterpret window messages as necessary events Use WM_USER+xUse WM_USER+x

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Using MessageWindowUsing MessageWindow

Pass window handle of MessageWindow class to native DLLPass window handle of MessageWindow class to native DLL

When native DLL detects event, use SendMessage to send When native DLL detects event, use SendMessage to send WM_USER+x message to MessageWindow classWM_USER+x message to MessageWindow class

When MessageWindow derived class receives message, fire When MessageWindow derived class receives message, fire event to signal ‘other’ managed code.event to signal ‘other’ managed code.

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Compact Framework 2.0Compact Framework 2.0

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V2 .NET CF ImprovementsV2 .NET CF Improvements

Performance improvementsPerformance improvements Better JIT’erBetter JIT’er Often used paths optimizedOften used paths optimized

XML SerializationXML Serialization Schema Schema XSD XSD C# Classes C# Classes

XML SchemasXML Schemas

XPathXPath

SQL CE Result SetSQL CE Result Set Typed direct access to SQL CE databaseTyped direct access to SQL CE database Works with DataBinderWorks with DataBinder

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V2 .NET CF ImprovementsV2 .NET CF Improvements

Improved support for COM interopImproved support for COM interop Runtime Callable wrappersRuntime Callable wrappers Improved marshalling supportImproved marshalling support

More typesMore types Embedded arraysEmbedded arrays MarshalAs attributeMarshalAs attribute

Additional controls supportedAdditional controls supported Web BrowserWeb Browser Doc ListDoc List Date/Time PickerDate/Time Picker Rich InkRich Ink Month CalendarMonth Calendar SplitterSplitter Link LabelLink Label Data ContainerData Container Notification BubbleNotification Bubble

Control’s window handle exposedControl’s window handle exposed

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V2 Language ImprovementsV2 Language Improvements

Compact Framework picks up the improvements to the C# Compact Framework picks up the improvements to the C# compiler scheduled for Visual Studio 2005compiler scheduled for Visual Studio 2005

Generics Generics Anonymous methodsAnonymous methods Partial Classes Partial Classes

VB developers get the My* namespaceVB developers get the My* namespace

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V2 Base Class Library ImprovementsV2 Base Class Library Improvements

Serial Port ClassSerial Port Class

Registry ClassRegistry Class

Cryptology ClassesCryptology Classes

ClipboardClipboard

Messaging Messaging

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New XML/Database SupportNew XML/Database Support

XML SerializationXML Serialization Schema Schema XSD XSD C# Classes C# Classes

XML SchemasXML Schemas

XPathXPath

SQL CE Result SetSQL CE Result Set Typed direct access to SQL CE databaseTyped direct access to SQL CE database Works with DataBinderWorks with DataBinder

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SummarySummary

Try to avoid interopTry to avoid interop

Calling native code is fairly straightforward Calling native code is fairly straightforward

Use eVC help and “Where defined”Use eVC help and “Where defined”

Export unmangled DLL functions Export unmangled DLL functions

Remember you’re still on Windows CERemember you’re still on Windows CE

2.0 looks cool2.0 looks cool

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Suggested Reading And Resources

Visit the Microsoft Press Kiosk today to receive Visit the Microsoft Press Kiosk today to receive 40%40% off books off books purchased from Amazon.compurchased from Amazon.com

Microsoft Press books are available at the TechEd Bookstore Microsoft Press books are available at the TechEd Bookstore and also at the Ask the Experts area in the Expo Halland also at the Ask the Experts area in the Expo Hall

The tools you need to put technology to work!The tools you need to put technology to work!

TITLETITLE AvailableAvailable PricePrice

TodayToday $59.99$59.99Programming Microsoft Programming Microsoft Windows CE .NETWindows CE .NET®®

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QuestionsQuestions

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