Let's suppose you have a C# class that acts as a server and you need clients to consume it across network.
There are two options:
This will create a COM+ application called calctest and hosts SillyCalc.WSC as shown below
The output
Managed COM component
Add the component in a COM+ application by executing the command:
The output
Set breakpoint and debugger breaks.
There are two options:
- DCOM via COM+
- WCF
Presently .NET framework provides RCW (Remote callable wrapper) mechanism for .NET code to interface with COM components. However it does not support late binding and has following limitations notably:
- Early bound requires tlb or dll to be part of the project for unmanaged dlls
- Managed com dlls cannot be consumed using tlb by managed client
- Don't support remote activation to work across network.
- Generate C# based late binding client code
- Generate VBScript based late binding client code
- Generate remote registration files
- Supports .Net framework 3.5
- Generate code that can be deployed as a WCF Server using COM+ Integration
- Generate code to start and stop COM+ application
Example
WSC COM component
As described in the previous post, use sillycalc.wsc. Load the wsc file as shown below and generate the wrapper code.
Add the component in a COM+ application by executing the command
COM+ services offers features such as thread pooling, object pooling, just in time activation, security etc. These services can be availed by hosting COM components in a COM+ application.
This also allows the COM component to be consumed across the network using DCOM.
ComAppHelper.exe -ins -app:testcalc -reg D:\Github\TechBlog\COM+\WSC\server\sillycalc.wsc
C# client
The
outputfile.cs contains a class COM_LB_SillyCalc_WSC_1 which can be
instantiated to create a proxy for the server. This class also contains wrapper
code for calling the methods and properties defined in the server.
Below is an
example:
class Program
{
public static void Main()
{
var lbclient = new COM_LB_SillyCalc_WSC_1("127.0.0.1");
Console.WriteLine("40+6={0}", lbclient.add(40, 6));
}
}
VBScript client
outputfile.vbs
contains a class COM_LB_SillyCalc_WSC_1 which can be
instantiated to create a proxy for the server. This class also contains wrapper
code for calling the methods and properties defined in the server.
Add
following at the bottom of outputfile.vbs, Edit add function to remove set.
set x = new COM_LB_SillyCalc_WSC_1
x.createcomobject("127.0.0.1")
msgbox (x.add(10,2))
Execute as
shown below:
cscript outputfile.vbs
The output
Managed COM component
As described in the previous post, use CalcServer.Calucalator. Load the dll file as shown below and generate the wrapper code.
Add the component in a COM+ application by executing the command:
ComAppHelper.exe -ins -app:calctest -reg -runforever D:\Github\TechBlog\COM+\Managed\server\bin\CalcServer.dll
This will create a COM+ application called calctest and hosts CalcServer.dll as shown below
C# client
The outputfile.cs contains a class COM_LB_CalcServer_Calucalator which can be instantiated to create a proxy for the server. This class also contains wrapper code for calling the methods and properties defined in the server.
Below is an example:
class Program
{
public static void Main()
{
var lbclient = new COM_LB_CalcServer_Calucalator("127.0.0.1");
Console.WriteLine("40+6={0}", lbclient.add(40, 6));
}
}
VBScript client
outputfile.vbs contains a class COM_LB_CalcServer_Calucalator which can be instantiated to create a proxy for the server. This class also contains wrapper code for calling the methods and properties defined in the server.
Add following at the bottom of outputfile.vbs, Edit add function to remove set.
set remoteclient = new COM_LB_CalcServer_Calucalator
remoteclient.CreateComObject "127.0.0.1"
msgbox remoteclient.add(10,2)
Execute as shown below:
cscript outputfile.vbs
The output
Debugging a Component in COM+ Application
To debug, simply attach to the dllhost process in visual studio. 
Make sure correct pdb files are copied.
Set breakpoint and debugger breaks.
