Building a Managed C++ Client using Early Binding by Gopalan Suresh Raj

Classic COM to .NET Interoperability
Building a Managed C++ Client using Early Binding

With early binding you import complete type information about a COM class at compile time. The compiler takes this information from the metadata assembly that is generated for the COM class.

Create a Visual C++, managed Application project. In our sample we use a managed C++ class as the client. To create the client you can use the Visual Studio AppWizard. Choose 'Managed C++ managed Application' as the target, I called the project QuoteClient, so the main source is called QuoteClient.cpp.

Clients that use COM objects should import metadata. In C++ you should use #using directive. The syntax is:

#using "filename"

where filename is the name of the metadata assembly.

Metadata should be accessible at compile time as well as at run time, so for simplicity, lets place QuoteServer.dll in the folder where your client code is located, as well as in the debug and release subfolders. As an alternative you can put the assembly in the folder with the client executable and reference it from source using a relative path.

Add the following line to QuoteClient.cpp file

#using "QuoteServer.dll"

At runtime the program finds the metadata assembly, uses this information to create a Runtime Callable Wrapper (RCW) object that is responsible for:

The RCW itself is a managed object so it is garbage collected. To import the library namespace, you should use the using namespace directive. Add the following line to your code

using namespace SimpleStocks;

QuoteClient.cpp

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// This is the main project file for VC++ application project
// generated using an Application Wizard.

#include "stdafx.h"

#using <mscorlib.dll>
#using "QuoteServer.dll"

using namespace System;
using namespace SimpleStocks;

// This is the entry point for this application
#ifdef _UNICODE
int wmain(int argc, char* argv[])
#else
int main(int argc, char* argv[])
#endif
{
  String *symbol = new String( "iCommware" );
  if (argc > 1) {
    symbol = new String( argv[1] );
  }
  else {
    Console::WriteLine( S"Usage: QuoteClient <symbol>" );
    Console::Write( S"Assuming Stock symbol is " );
    Console::WriteLine( String::Concat( symbol, " and proceeding..." ) );
  }

  // Create the Server Object
    QuoteServer *pQuoteServer = new QuoteServer;
  // Invoke operations on the Server
    float price = pQuoteServer->getQuote( symbol );

  Console::Write( "The price of " );
  Console::Write( String::Concat( symbol, " is : US $" ) );
  Console::WriteLine( price );

    return 0;
}

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	Classic COM to .NET Interoperability
	Developing a Classic COM Server Component using C# and .NET - The QuoteServer Example
	Developing a Classic COM Client Application using Visual Basic ver 6.0 to access the QuoteServer - The VB6Client Example
	Developing a Managed C++ Client Application which binds to the Server using Early Binding - The QuoteClient Example
	Developing a Managed C++ Client Application which binds to the Server using Late Binding - The cppLateBinding Example