Introduction to the Compact Framework

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Introduction to the Compact Framework

• Marcus Perryman
• Principal Consultant
• Microsoft

2
Agenda

• Design goals
• Key components
• Common features with the desktop
• Differences from the desktop
• Whats in and out

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What is Compact FrameworkDesign Goals

• Target mobile and embedded devices
• Portable subset of .NET Framework
• No new compact namespaces
• Visual Basic .NET C compiler support in v1
• Leverage Visual Studio .NET
• Run managed .EXEs and .DLLs directly
• Debug with Visual Studio .NET
• Peacefully co-exist with host OS
• Run on native threads, P/Invoke to call native
  code

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Key Components
.NET Compact Framework
Applications
App Domain Host
Execution Engine (MSCOREE.DLL) - CLR
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Compact CLR Common Features

• Verifiable type safe execution
• No uninitialized variables, unsafe casts, bad
  array indexing, bad pointer math
• Garbage Collection
• No ref-counting, no leaks
• JIT compilation
• Error handling with exceptions
• Common type system
• Call, inherit, and source-level debug across
  different languages

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Compact CLR Differences

• COM Interop
• Good support for calling native DLLs
• Support for calling a COM object through DLL
  wrappers
• No support for writing a COM / ActiveX object in
  C or Visual Basic
• No Install-time JIT (nGen)
• No Reflection Emit
• No Remoting
• Client web services is fully supported
• No Generic Serialization
• Datasets can be serialized to XML
• Subsets of other areas of functionality

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.NET Compact Framework
System.Web
System.WinForms
Services
UI
Design
ComponentModel
Description
HtmlControls
Discovery
WebControls
System.Drawing
Protocols
Caching
Security
Drawing2D
Printing
Text
Configuration
SessionState
Imaging
System.Data
System.Xml
ADO.NET
SqlClient
XmlDocument
Serialization
Design
SqlServerCe
Xslt/XPath
Reader/Writers
System
Collections
IO
Configuration
Runtime
InteropServices
Security
Net
ServiceProcess
Remoting
Text
Reflection
Diagnostics
Serialization
Globalization
Resources
Threading
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Supported Controls

• Supported controls

HScrollBar ImageList Label ListBox ListView TreeVi
ew FileSaveDialog
MainMenu NumericUpDown Panel PictureBox ProgressBa
r RadioButton
StatusBar TabControl TextBox Timer ToolBar VScroll
Bar

• Button
• CheckBox
• ComboBox
• ContextMenu
• DataGrid
• DomainUpDown
• FileOpenDialog

• Unsupported controls

GroupBox Printing Controls
RichTextBox
NotificationBubble (PPC)

• Unsupported controls not available in CE

HelpProvider LinkLabel NotifyIcon
ToolTip Splitter FontDialog
CheckedListBox ColorDialog ErrorProvider
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Framework Size

• Framework size (RAM or ROM)
• 1.5 MB
• Running RAM needs
• 1 MB (depends on app)
• Typical application sizes
• 5 - 100 KB
• Apps often smaller due to use of platform
  features in the framework

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DEMO

• Creating a basic form
• Consuming a web service

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Advanced .NET Compact Framework Development
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Agenda

• Under the hood what goes on with CF
• JIT, GC and Pitching
• Performance
• The art of tuning
• Platform Interop
• Getting to native code
• Marshalling
• Callbacks
• Summary

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Under the hood
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Architecture
.NET Compact Framework
Applications
App Domain Host
Execution Engine (MSCOREE.DLL)
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The EEA short review

• Compiled managed code is a binary in Microsoft
  Intermediate Language
• Code is just-in-time compiled to the native
  processor language on type-by-type,
  method-by-method basis
• Resulting native code is cached for later reuse
• Over the lifetime of the app, the up front cost
  of jitting is amortized, and becomes less and
  less significant

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Under the Hood

• Build process
• Same compilers
• Local exe produced additional Deploy step
• File format
• Standard PE format with no native code
• Module load upgraded on device
• Contains Intermediate Language (IL) blocks
• Resources bound in or deployed in parallel
• Deploy
• Uses Connection Manager not Platform Manager
• Again over Active Sync

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DEMO

• ILDASM
• Multiple environments

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Remote Deploy And Debug
Active Sync
Connection Manager
Device or Emulator
Windows
Visual Studio .NET
Debug Manager
App.pdb
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Per-Thread Control Flow
Execute Managed Method
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Garbage Collection

• Desktop

G 0
G 1
G 2
Mark
Mark
2k
Promote
Promote
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Garbage Collection

• Compact Framework

Threshold
Mark
Compact
Pitch Code? LRU
5K
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Performance
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What Is Performance?
Application performance is qualitatively measured
by how responsive the application is to the end
user

• Affected by two principles
• Absolute Performance of the system the raw
  processing horsepower
• Apparent Performance of the application affected
  by how the application is written

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Code Pitching

• Occurs when large volumes of allocated memory
  cause memory pressure
• Runtime will discard or pitch code from the code
  cache
• Qualitative inspection will tell you when this
  occurs

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Behavior Under Memory Pressure
Performance
Memory utilization
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Compact Framework Performance

• User Interface
• Version 1 performance is excellent!
• System.Drawing and System.Windows.Forms call to
  native APIs beneath
• Call batching where possible
• Pools and reuses Window Handles
• Data And XML Performance
• Version 1 performance is good
• Mostly implemented in managed code
• Memory pressure effect data perfomance

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Performance Tuning

• Analyze Performance of Application
• Discover where the application is slow
• Choose where to optimize
• Whats important to the customer scenarios?
• Understand The APIs
• How abstract is the API?
• Example XmlDocument vs XmlTextReader/Writer
• What work has to happen under the hood?
• Be aware of how events fire
• Keep responsiveness

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Performance Tips and Tricks
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Execution Engine

• Dont call GC.Collect()!
• Minimize the number of function calls
• Consider making functions larger rather than
  having incredibly deep call stacks
• Make use of asynchronous calls where useful, but
  avoid creating too many threads
• Reduce, reuse, recycle!
• The less memory you allocate, the faster your app
  will be!

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User Interface

• Reduce number of method calls
• Example use Control.Bounds instead of
  Control.Location Control.Size
• Create the Window tree top down, rather than
  bottom up
• Opposite of what VS.NET does by default
• Minimize control addition on Form.Load()
• Defer loading of controls until they are used

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Handling Data

• Make asynchronous requests
• Defer data loading until it is required, discard
  when data no longer in use
• Minimize data in memory at any time
• Forward only reading is always faster than in
  memory representations
• XmlDocument versus XmlTextReader
• DataReader versus DataAdapter
• Use StringBuilder for complex string
  manipulations

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Interop
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Types Of Native CodeInterop

• Calling native DLLs from C and VB .NET
• DLL Interop with P/Invoke is supported
• Some limitations
• No support for COM Interop
• Some COM support through P/Invoke and DLL
  wrappers
• Exposing managed code objects as native DLLs, COM
  or ActiveX objects
• Not supported

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Overall Native CodeInterop strategy

• Focus on enabling versus exhaustive
• PInvoke is powerful, but advanced or edge case
  scenarios are more difficult than the desktop
• It is possible for COM and .NET components to
  peacefully coexist in the same process/thread
• Focus on simplicity for Version 1.0
• Native code interop is very fast and simple

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Platform InvocationPInvoke

• Allows users to call custom native code and
  Windows APIs
• Declare statement in Visual Basic
• DLLImport Attribute in C
• Very flexible
• Good support on the device
• Extensively used in Forms and other parts of the
  framework

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Simple ExampleMessageBox

• int MessageBox(
• HWND hWnd,
• LPCTSTR lpText,
• LPCTSTR lpCaption,
• UINT uType )

DllImport("coredll.dll") private static extern
int MessageBox( IntPtr hWnd, string lpText,
string lpCaption, uint uType)
Private Declare Function MessageBox Lib
"coredll.dll" ( _ ByVal hwndOwner As IntPtr,
_ ByVal lpText As String, _ ByVal lpCaption
As String, _ ByVal uType As Integer) As
Integer
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MessageBox

• using System.Runtime.InteropServices
• DllImport("coredll.dll")
• private static extern int MessageBox(
• IntPtr hWnd,
• string lpText,
• string lpCaption,
• uint uType)
• MessageBox(IntPtr.Zero, "Hello World!",
  "Interop1", 0)

• Loads and initialises coredll.dll
• Locates the entry point MessageBox
• Calls into the unmanaged code
• Completes and returns back to managed code

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DEMO

• Calling MessageBox

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Data Marshaling

• Simple Types
• Direct Translation
• Simple Objects and ValueTypes
• Objects that contain simple types
• Execution engine points at the data of the object
• Some exceptions
• Complex Objects and Value Types
• Objects containing other objects need to manually
  marshal data

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Marshaling Of Simple Types

• The execution engine marshaling of simple data
  types

bool and Boolean DO NOT convert to a Win32 BOOL
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Marshaling Simple Objects

• Members of classes are always laid out
  sequentially
• Only classes containing simple types will be
  automatically marshaled

C public class Rect int left int top int
right int bottom
Native Code - C typedef struct _RECT LONG
left LONG top LONG right LONG bottom
RECT
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Marshaling Complex Objects

• Marshal class
• Located in System.Runtime.InteropServices
• Provides advanced functionality to customize
  marshaling
• Allows you to get copy managed objects into
  native code
• Allows you to read and write raw memory if needed

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DEMO

• Make a phone call

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Callbacks

• No support for direct native to managed function
  calls
• Use MessageWindow
• Part of Microsoft.WindowsCE.Forms
• Steps for Callback
• Create a MessageWindow in Managed
• Pass window handle to native
• Native sends messages back with it
• Managed code can trap window messages

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DEMO

• Using MessageWindow

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Summary

• Performance
• Understand what is acceptable for data
  freshness
• Think asynchronously for best UI performance
• Design, test and iterate on your design
  considering multiple approaches
• Reduce, reuse and recycle objects
• Interop
• Native DLL entry points can be called
• COM objects can be wrapped by std DLLs
• ActiveX controls not supported (3rd party
  solution)
• C and Visual Basic components cannot be exposed
  as COM components or ActiveX controls

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Advanced .NET Compact Framework Development
BRIEF In this session we will examine some of
the more advanced topics around .NET CF starting
with a look under the hood at what Compact
Framework actually does. We will consider some
design approaches and coding techniques that can
lead to higher performance of your application,
explore how to call and be called by native code,
see the flexibility in ADO.NET on the device and
finish by looking at the packaging, deployment
and installation options available.