COM+ Application: Detail steps to create COM+ Application

Article
1/17/2024

Introduction

What is COM+?

it is an extension of Component Object Model, Microsoft's strategic building block approach for developing application programs. COM+ is intended to provide a model that makes it relatively easy to create business applications that work well with the Microsoft Transaction Server (MTS) in a Windows NT or subsequent system.

COM+ consists of interfaces and Method.

In our Article, we will explain how to create COM+ application using C#.net.

We will make client in Vb6 and COM+ application server in C#.net.

We will do simple example addition and subtraction.

COM+ Application

Client: Vb6

Server: C#.net

Launch Visual Studio

Create New Project

Select Visual C# - Class Library

Add service System.EnterpriseServises.

It will be at below location.

Modify your AssemblyInfo.cs class as below

While modifying below lines, it will throw an error.

To solve this, add

using System.EnterpriseServices;’
 
[assembly: ApplicationName("ComPlus")]
[assembly: Description("COMPlus Assmebly")]
[assembly: ApplicationActivation(ActivationOption.Server)]
[assembly: ApplicationAccessControl(false)]
 
[assembly: ComVisible(true)]

Create an interface class.

Example iInterface.cs

Add below method in iInterface.cs (Addition and Subtraction)

Make sure our interface is public.

- Add new class name ‘ComPlusClass’.

Implement Interface iInterface.

Add below code in class ‘ComPlusClass’

; Male sure class is public

Build the application

Make sure there are no error and build successful

We have to create strong key which we need to assign to the application

We will use VS command prompt to create it

Note: it is strong key name so name should be same as project name otherwise it won’t work

Our project name is: COMPlus

- Launch VS command prompt

Locate to your project folder

Type

sn -k COMPlus.snk**

- Add this strong key to the project

Application properties -> Signing -> Check the check Box (Sign the assembly)

Locate the key which is created in above steps

Compile the project in release mode

We have moved this strong key in release folder so it would be easy to use

Build/Rebuild the application

Next step to register the assembly

Use VS tool to register it

Locate to the release folder

Type:

regasm ComPlusExample.DLL

- Create Type Library using the same tool

Type:tlbexp COMPlus.DLL

Confirm that tlb file is created in release folder.

- Next step is to register the created COM+ application

Type: regsvcs COMPlus.DLL

-To view this registered COM+

go to Control Panel -> Administrative Tools -> Component Services. In Component Services -> Computers -> My Computer -> Com + Applications.

We have successfully created COM+ application.

Now let’s create client in VB6.

- Create new project

- Add two text box, one button

- Add reference of created assembly

Project -- References – Locate tlb file – Add

- Copy paste below code

Option Explicit
  
Private Sub  btnAddition()
Dim comAssembly As iInterface
Dim i As Integer
Dim a As Integer
Dim b As Integer
Dim c As Integer
  
Set comAssembly = New ComPlusClass 
  
a = Val(txtFirstNumber.Text)
b = Val(txtSecondNumber.Text)
  
c = comAssembly.Addition(a, b)
txtResult.Text = c
  
End Sub
  
Private Sub  btnSubtraction()
  
Dim comAssembly As iInterface
  
Set comAssembly = New ComPlusClass
Dim a As Integer
Dim b As Integer
Dim c As Integer
  
a = Val(txtFirstNumber.Text)
b = Val(txtSecondNumber.Text)
  
'Subtraction
  
c = comAssembly.Subtraction(a, b)
txtResult.Text = c
  
  
End Sub

- Compile the project

-Run the project

Addition: