使用 COM+ 管理目录的介绍性示例

以编程方式使用 COM+ 管理员目录时，通常执行以下常规步骤（此处未按严格顺序提供）：

• 在本地计算机上打开与 COM+ 目录的会话。 （可选）连接到远程计算机上的 COM+ 目录。
• 执行诸如启动或停止服务之类的操作，这些操作与特定的 COM+ 应用程序无关。
• 执行一些操作，如安装或导出 COM+ 应用程序，或将组件安装到应用程序中，这些操作与读取或写入文件有关。
• 向集合中添加新项，例如通过向“Applications”集合中添加一个新项来创建新的 COM+ 应用程序。
• 设置或获取集合中项的属性。
• 保存或放弃对目录的挂起更改。
• 处理可能发生的任何错误。

为了显示使用 COMAdmin 对象时这些步骤的外观，下面提供了 Microsoft Visual Basic 示例。 其中简要说明了上面描述的一些典型步骤，例如查找集合、枚举集合以检索项以及设置该项的属性。

在下面的示例中，将执行以下操作：

1. 创建新的 COM+ 应用程序“MyHomeZoo”。
2. 在应用程序中安装一些组件 Cat 和 Dog。 这两个组件都包含在一个必须已经存在的 DLL 中：MyZoo.DLL。
3. 通过定义两个角色为应用程序配置基于角色的安全性：ZooKeeper 和 AllergicToCats。
4. 为整个应用程序分配 ZooKeeper 角色访问权限。
5. 将 AllergicToCats 角色访问权限仅分配给 Dog 组件。
6. 启用安全属性，以便为应用程序强制实施角色检查。
7. 将 MyHomeZoo 应用程序导出到文件，以便可以将其安装在其他计算机上。

若要在 Visual Basic 中使用此示例，请添加对 COM+ 管理类型库的引用。

Function SetupMyZoo() As Boolean  ' Return False if any errors occur.

    '  Initialize error handling for this function.
    SetupMyZoo = False 
    On Error GoTo My_Error_Handler

    '  Open a session with the catalog.
    '  Instantiate a COMAdminCatalog object. 
    Dim objCatalog As COMAdminCatalog
    Set objCatalog = CreateObject("COMAdmin.COMAdminCatalog")

    '  Create a new COM+ application.
    '  First get the "Applications" collection from the catalog.
    Dim objApplicationsColl As COMAdminCatalogCollection
    Set objApplicationsColl = objCatalog.GetCollection("Applications")

    '  Add a new item to this collection. 
    Dim objZooApp As COMAdminCatalogObject
    Set objZooApp = objApplicationsColl.Add

    '  The "Applications" collection determines the available properties.
    '  Set the "Name" property of the new application item. 
    objZooApp.Value("Name") = "MyHomeZoo"

    '  Set the "Description" property of the new application item. 
    objZooApp.Value("Description") = "My pets at home"

    '  Save changes made to the "Applications" collection. 
    objApplicationsColl.SaveChanges

    '  Install components into the application.
    '  Use the InstallComponent method on COMAdminCatalog. 
    '  In this case, the last two parameters are passed as empty strings.
    objCatalog.InstallComponent "MyHomeZoo","MyZoo.DLL","","" 

    '  Define the roles ZooKeeper and AllergicToCats 
    '  by adding them to the "Roles" collection related to MyHomeZoo. 
    '  First get the "Roles" collection related to MyHomeZoo.
    '  Use the GetCollection method on COMAdminCatalogCollection,
    '  passing in the name of the desired collection, "Roles", 
    '  and the Key property value of objZooApp.   
    '  The Key property uniquely identifies the object, serving
    '  here to distinguish the "Roles" collection related 
    '  to MyHomeZoo from that of any other application. 
    Dim objRolesColl As COMAdminCatalogCollection
    Set objRolesColl = objApplicationsColl.GetCollection("Roles", objZooApp.Key)

    '  Add new items to this "Roles" collection. 
    Dim objZooKeeperRole As COMAdminCatalogObject
    Dim objAllergicToCatsRole As COMAdminCatalogObject
    Set objZooKeeperRole = objRolesColl.Add
    Set objAllergicToCatsRole = objRolesColl.Add

    '  Set the "Name" for the new items.
    objZooKeeperRole.Value("Name") = "ZooKeeper" 
    objAllergicToCatsRole.Value("Name") = "AllergicToCats" 

    '  Save changes made to any items in this "Roles" collection. 
    objRolesColl.SaveChanges

    '  Assign the AllergicToCats role to the Dog component to 
    '  restrict its scope of access. (The ZooKeeper role, if assigned
    '  only at the application level, can access the whole application.)
    '  First get the "Components" collection related to MyHomeZoo.
    '  Use the GetCollection method on COMAdminCatalogCollection,
    '  passing in the name of the desired collection, "Components", and
    '  the Key property value of objZooApp. 
    Dim objZooComponentsColl As COMAdminCatalogCollection
    Set objZooComponentsColl = objApplicationsColl.GetCollection("Components", objZooApp.Key) 

    '  Find the Dog component item in this "Components" collection.
    '  First Populate the collection to read in data for all its items. 
    objZooComponentsColl.Populate

    '  Enumerate through the "Components" collection 
    '  until the Dog component item is located. 
    Dim objDog As COMAdminCatalogObject 
    For Each objDog in objZooComponentsColl
        If objDog.Name = "Dog" Then 
            Exit For
        End If
    Next 
    '  Set the role checking property at the component level for Dog.
        objDog.Value("ComponentAccessChecksEnabled") = True 

    '  Save these changes.
        objZooComponentsColl.SaveChanges
    '  Get the "RolesForComponent" collection related to the 
    '  Dog component, using the Key property of objDog. 
    Dim objRolesForDogColl As COMAdminCatalogCollection 
    Set objRolesForDogColl = objZooComponentsColl.GetCollection("RolesForComponent", objDog.Key) 

    '  Add a new item to this "RolesForComponent" collection. 
    Dim objCatSneezerRole As COMAdminCatalogObject
    Set objCatSneezerRole = objRolesForDogColl.Add

    '  Set the "Name" of the new item to be "AllergicToCats". 
    objCatSneezerRole.Value("Name") = "AllergicToCats" 

    '  Save changes made to this "RolesForComponent" collection. 
    objRolesForDogColl.SaveChanges

    '  Now set properties to enforce role-based security. 
    '  First set role-based security at the application level.
    objZooApp.Value("ApplicationAccessChecksEnabled") = True 
    objZooApp.Value("AccessChecksLevel") = COMAdminAccessChecksApplicationComponentLevel 

    '  Save these changes.
    objApplicationsColl.SaveChanges

    '  Finally, export the new configured MyHomeZoo application to an 
    '  MSI file, used to install the application on other machines.
    '  Use the ExportApplication method on COMAdminCatalogObject.
    objCatalog.ExportApplication "MyHomeZoo", "c:\Program Files\COM applications\MyHomeZoo.MSI", 4

    '  Exit the function gracefully.
    SetupMyZoo = True

My_Error_Handler:
    If Not SetupMyZoo Then
        MsgBox "Error # " & Err.Number & " (Hex: " & Hex(Err.Number) & ")" & vbNewLine & Err.Description
    End If
    objCatSneezerRole = Nothing
    objRolesForDogColl = Nothing
    objDog = Nothing
    objZooComponentsColl = Nothing
    objAllergicToCatsRole = Nothing
    objZooKeeperRole = Nothing
    objRolesColl = Nothing
    objZooApp = Nothing
    objApplicationsColl = Nothing
    objCatalog = Nothing
Exit Function

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