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Browsing the WMI Schema

Browsing the WMI Schema

.NET Framework 1.1

The following code example shows an application that allows the user to browse the available WMI classes in a specified namespace:

using System;
using System.Collections;
using System.ComponentModel;
using System.Management;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;

namespace SchemaBrowser
{
   /// <summary>
   /// This application browses WMI classes available in the local namespace entered.
   /// </summary>
   public class WebForm1 : System.Web.UI.Page {
      protected System.Web.UI.WebControls.Label Label1;
      protected System.Web.UI.WebControls.TextBox namespaceValue;
      protected System.Web.UI.WebControls.Button searchButton;
      protected System.Web.UI.WebControls.ListBox classList;
      protected System.Web.UI.WebControls.Label Label3;
      protected System.Web.UI.WebControls.Label statusValue;
      protected System.Web.UI.WebControls.Label Label2;
      private int count;
   
      public WebForm1() {
         Page.Init += new System.EventHandler(Page_Init);
      }

      private void Page_Init(object sender, EventArgs e) {
         count = 0;
         InitializeComponent();
      }

      private void InitializeComponent() {    
         this.searchButton.Click += 
            new System.EventHandler(this.searchButton_Click);
      }

      private void searchButton_Click(object sender, System.EventArgs e) {
         // Initialize class counter and clear list view.
         count = 0;
         this.classList.Items.Clear();

         if (namespaceValue.Text.Equals("")) {
            this.AddNamespacesToList();
         }
         else {
            this.AddClassesToList();
         }
      }

      private void AddNamespacesToList() {
         try {
            // Enumerate all WMI instances of __namespace WMI class.
            ManagementClass nsClass = new ManagementClass(
               new ManagementScope("root"),
               new ManagementPath("__namespace"),
               null);
            foreach(ManagementObject ns in nsClass.GetInstances()) {
               this.classList.Items.Add(ns["Name"].ToString());
               count++;
            }
            this.statusValue.Text = count + " namespaces found.";
         }
         catch (Exception e)   {
            this.statusValue.Text = e.Message;
         }
      }

      private void AddClassesToList() {
         try {   
            // Perform WMI object query on selected namespace.
            ManagementObjectSearcher searcher = new ManagementObjectSearcher(
                new ManagementScope(namespaceValue.Text),
               new WqlObjectQuery("select * from meta_class"),
               null);               
            foreach (ManagementClass wmiClass in searcher.Get()) {
               this.classList.Items.Add(wmiClass["__CLASS"].ToString());
               count++;
            }
            this.statusValue.Text = count + " classes found.";
         }
         catch (Exception ex) {
            this.statusValue.Text = ex.Message;
         }
      }
   }
}

[Visual Basic]
Imports System
Imports System.Collections
Imports System.ComponentModel
Imports System.Management
Imports System.Drawing
Imports System.Web
Imports System.Web.SessionState
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.HtmlControls

Namespace SchemaBrowser
   ' This application browses WMI classes available in local 
   ' namespace entered.
   Public Class WebForm1
      Inherits System.Web.UI.Page
      Protected Label1 As System.Web.UI.WebControls.Label
      Protected namespaceValue As System.Web.UI.WebControls.TextBox
      Protected searchButton As System.Web.UI.WebControls.Button
      Protected classList As System.Web.UI.WebControls.ListBox
      Protected Label3 As System.Web.UI.WebControls.Label
      Protected statusValue As System.Web.UI.WebControls.Label
      Protected Label2 As System.Web.UI.WebControls.Label
      Private count As Integer


      Public Sub New()
         AddHandler Page.Init, AddressOf Page_Init
      End Sub 

      Private Sub Page_Init(sender As Object, e As EventArgs)
         count = 0   
         InitializeComponent()
      End Sub 

      Private Sub InitializeComponent()
         AddHandler searchButton.Click, AddressOf Me.searchButton_Click         
      End Sub
      
      Private Sub searchButton_Click(sender As Object, e As System.EventArgs) 
         ' Initialize class counter and clear list view.
         Me.statusValue.Text = "!!!"
         count = 0
         Me.classList.Items.Clear()    
         If namespaceValue.Text.Equals("") Then
            Me.AddNamespacesToList()
         Else
            Me.AddClassesToList()
         End If
      End Sub 
       
      Private Sub AddNamespacesToList()
         Try
            ' Enumerate all WMI instances of __namespace WMI class.
            Dim nsClass As New ManagementClass( _
               New ManagementScope("root"), _
               New ManagementPath("__namespace"), _
               Nothing)
            Dim ns As ManagementObject
            For Each ns In  nsClass.GetInstances()
            Me.classList.Items.Add(ns("Name").ToString())
            count += 1
            Next ns
            Me.statusValue.Text = count & " namespaces found."
         Catch e As Exception
            Me.statusValue.Text = e.Message
         End Try
      End Sub 
      
      
      Private Sub AddClassesToList()
         Try
            ' Perform WMI object query on selected namespace.
            Dim searcher As New ManagementObjectSearcher( _
               New ManagementScope(namespaceValue.Text), _
               New WqlObjectQuery("select * from meta_class"), _
               Nothing)
            Dim wmiClass As ManagementClass
            For Each wmiClass In  searcher.Get()
            Me.classList.Items.Add(wmiClass("__CLASS").ToString())
            count += 1
            Next wmiClass
            Me.statusValue.Text = count & " classes found."
         Catch ex As Exception
            Me.statusValue.Text = ex.Message
         End Try
      End Sub 
   End Class 
End Namespace
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