Knowledge Base

HOW TO: Access the Registry on a Remote Computer by Using Visual Basic 6.0 and the Windows API

Article ID: 315586

Article Last Modified on 10/26/2002

APPLIES TO

Microsoft Visual Basic 6.0 Enterprise Edition

This article was previously published under Q315586

IN THIS TASK

SUMMARY

Requirements
Create a Demonstration Application
Verification

REFERENCES

SUMMARY

This article explains how to use a Visual Basic application to access the registry on a remote computer in conjunction with the Windows application programming interface (API).

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Requirements

You need the following hardware and software to perform the procedures in this article:

A Microsoft Windows XP, Microsoft Windows 2000, or Microsoft Windows NT 4.0-based computer
Visual Basic 6.0

NOTE: If the remote registry is on a system that is running Windows NT 4.0, Windows 2000, or Windows XP, you must run the code from an account that has permission to read that registry.

You also need the following skills:

Visual Basic 6.0 programming experience
Familiarity with the Windows registry

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Create a Demonstration Application

Start Visual Basic 6.0, and then create a new project of type Standard EXE.
Right-click the form, and then click View Code on the Shortcut menu. Add the following statement at the start of the code:
```
Option Explicit
                    
```

Add the following code to declare the constants used to access the registry:

Private Const HKEY_CLASSES_ROOT = &H80000000
Private Const HKEY_CURRENT_USER = &H80000001
Private Const HKEY_LOCAL_MACHINE = &H80000002
Private Const HKEY_USERS = &H80000003

Private Const KEY_QUERY_VALUE = &H1
Private Const KEY_SET_VALUE = &H2
Private Const KEY_ALL_ACCESS = &H3F

Private Const REG_SZ  As Long = 1
Private Const ERROR_SUCCESS = 0&

Add the following code to declare the entry points for the registry functions in the Windows application programming interface (API):

Private Declare Function RegConnectRegistry Lib "advapi32.dll" _
Alias "RegConnectRegistryA" _
    (ByVal lpMachineName As String, _
     ByVal hKey As Long, _
     phkResult As Long) As Long

Private Declare Function RegCloseKey Lib "advapi32.dll" _
    (ByVal hKey As Long) As Long

Private Declare Function RegOpenKeyEx Lib "advapi32.dll" _
Alias "RegOpenKeyExA" _
    (ByVal hKey As Long, _
     ByVal lpSubKey As String, _
     ByVal ulOptions As Long, _
     ByVal samDesired As Long, _
     phkResult As Long) As Long
   
Private Declare Function RegQueryValueExString Lib "advapi32.dll" _
Alias "RegQueryValueExA" _
    (ByVal hKey As Long, _
     ByVal lpValueName As String, _
     ByVal lpReserved As Long, _
     lpType As Long, _
     ByVal lpData As String, _
     lpcbData As Long) As Long

Add the following global variable declaration:

Private hRemoteReg As Long

Add the following code to handle the Form_Load event. This code calls the RegConnectRegistry function to connect to the remote registry. Replace the \\RemoteMachineName parameter with the name of the computer whose registry you want to access:

Private Sub Form_Load()
    Dim lRet As Long
    
    'Connect to the remote registry 
    lRet = RegConnectRegistry("\\RemoteMachineName", _
                              HKEY_LOCAL_MACHINE, _
                              hRemoteReg)
    
    If (lRet = ERROR_SUCCESS) Then
        MsgBox "Successfully connected to remote registry"
    Else
        MsgBox "Error:" & Err.LastDllError
        Unload Me
        Exit Sub
    End If
End Sub

Add the following code to handle the Form_Unload event:

Private Sub Form_Unload(Cancel As Integer)
    Dim lRet As Long
    If hRemoteReg <> 0 Then
        lRet = RegCloseKey(hRemoteReg)
    End If
End Sub

In the Form Designer, add a Command control to the form. The control has the default name of Command1.

Double-click Command1 to create a click handler for the command button. Add the following code to the click handler function:

Private Sub Command1_Click()
    Dim lRetVal As Long
    Dim hKey As Long
    Dim sValue As String
    
    lRetVal = RegOpenKeyEx(hRemoteReg, _
        "HARDWARE\DESCRIPTION\System", 0, KEY_QUERY_VALUE, hKey)
    If lRetVal <> ERROR_SUCCESS Then
        MsgBox "Cannot open key"
    Else
        sValue = String(255, " ")
        lRetVal = RegQueryValueExString(hKey, _
            "SystemBIOSVersion", 0&, REG_SZ, sValue, 255)
        If lRetVal <> ERROR_SUCCESS Then
            MsgBox "Cannot query value"
        Else
            MsgBox sValue
        End If
        lRetVal = RegCloseKey(hKey)
        If lRetVal <> ERROR_SUCCESS Then
            MsgBox "Cannot close key"
        End If
    End If
End Sub

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Verification

Press F5 to build and run the application.
A message box appears, indicating that the registry on the remote computer has been contacted. Click OK.

The main form of the application appears.
Click Command1. The value stored in the following location in the remote registry is displayed:

HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\SystemBIOSVersion
To verify this registry value, run regedit.exe on the remote computer. In Registry Editor, click Find on the Edit menu. Type SystemBIOSVersion, and then click Find Next. After a short pause, Registry Editor displays the value for this key; verify that this is the same value displayed in your Visual Basic application.

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REFERENCES

For additional information, click the article number below to view the article in the Microsoft Knowledge Base:

145679 HOWTO: Use the Registry API to Save and Retrieve Setting

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Keywords: kbhowto kbhowtomaster kbinfo kbregistry kbapi KB315586

Microsoft KB Archive/315586

Contents

HOW TO: Access the Registry on a Remote Computer by Using Visual Basic 6.0 and the Windows API

IN THIS TASK

SUMMARY

Requirements

Create a Demonstration Application

Verification

REFERENCES