Registry Key attributes

A Registry Key object represents a registry key for installation or removal. You can add or remove keys, and you can optionally remove all their subkeys and values as well.

Installation or removal of a registry key is controlled by its component. If the component is installed, the registry key's Install action is executed (which may actually remove the key); if the component is removed, the Remove action is executed. If a registry key is not linked to a component, its Install action is executed during installation of your product, and its Remove action when the product is removed.

In addition to the explicit installation and removal actions, registry keys are automatically created if a subkey or value is installed under the key, and removed if they become empty (unless Remove action is set to Do not remove).

Registry key removal warning

Removing a non-empty registry key is potentially a dangerous operation, even more so if its subkeys are also removed. During the removal process, all values under the key (and potentially under its subkeys) are removed regardless of their installation status. This may cause serious problems on the target system. If at all possible, you should selectively remove registry values by using registry value installation and removal actions (see Registry Value).

Attributes

This pane contains the following attributes and options.

Attribute	Description
Key name	Enter the name of the registry key. You may use symbolic references in the name; they will be resolved when the registry key is installed.
Alias	Enter the alias for the registry key. This alias must be unique in the project. Tarma Installer uses the alias as if it were a symbolic variable; for example, you can use expressions like <@regkey_alias\value> to retrieve registry value data during installation.
Install action	Select the desired installation action from the drop-down list. The installation action is executed when the registry key's component is installed. If the registry key is not linked to a component, the action is executed when the product as a whole is installed. See Installation actions below for the full list of actions.
Remove action	Select the desired removal action from the drop-down list. The removal action is executed when the registry key's component is removed. If the registry key is not linked to a component, the action is executed when the product as a whole is removed. See Removal actions below for the full list of actions.
Registry view	Select the desired registry view from the drop-down list. See Registry views below for an explanation of registry views.

Installation actions

The installer can create or remove the registry key and its values during product installation.

Note: As a side effect, removal of a key may lead to removal of its parent key if the key is empty after the key is removed. This in turn may lead to removal of the grandparent key, etc.

Install action	Description
Create on demand	The registry key is created, if it does not already exist, when its first value or subkey is installed.
Create always	The registry key is created if it does not already exist, regardless of any values or subkeys under it.
Remove if empty	If the registry key exists but has no values or subkeys, it is removed. If it contains one or more values or subkeys, it is left as-is.
Remove key and values	If the registry key exists, its values (but not subkeys) are removed. If it contains no subkeys, the key itself is then removed. If it does contain one or more subkeys, the registry key is retained (but its values are gone).
Remove key and subkeys	If the registry key exists, its values and all of its subkeys are removed recursively, then the key itself is removed.

Removal actions

The installer can remove or retain the registry key during product removal.

Note: As a side effect, removal of a key may lead to removal of its parent key if the key is empty after the key is removed. This in turn may lead to removal of the grandparent key, etc.

Remove action	Description
Do not remove	The registry key is left as-is.
Remove if empty	If the registry key exists but has no values or subkeys, it is removed. If it contains one or more values or subkeys, it is left as-is.
Remove key and values	If the registry key exists, its values (but not subkeys) are removed. If it contains no subkeys, the key itself is then removed. If it does contain one or more subkeys, the registry key is retained (but its values are gone).
Remove key and subkeys	If the registry key exists, its values and all of its subkeys are removed recursively, then the key itself is removed.

Registry views

On 64-bit Windows systems, the registry is internally subdivided into 32-bit and 64-bit "views". 64-bit programs see the 64-bit version of the registry, while 32-bit programs see the 32-bit version. To a large extent these views are identical and correspond to the same underlying registry keys and values, but they may differ in the following ways:

Some 64-bit registry keys are mirrored in the 32-bit registry and vice versa, so although they are physically distinct, they contain the same values and data.
Some 64-bit registry keys co-exist with 32-bit registry keys that have the same name, but contain different values or data.

Microsoft introduced these different views to accommodate 64-bit and 32-bit software side-by-side on a single system, for example 32-bit and 64-bit versions of in-process COM servers such as ActiveX controls. In many cases the 64/32 registry distinction is either immaterial to an application, or the default registry view (64-64 or 32-32) achieves the desired result.

Tip: The different views apply at the registry key level; any registry values that you create use the same view as their parent key. It is not possible to change the registry view on a per-value basis; this must be done at the registry key level.

Note: These remarks and the following only apply to 64-bit Windows versions. On 32-bit Windows versions, there is only one registry view and all registry actions operate on that single view.

When do you need to be aware of registry views?

During installation of software on a 64-bit Windows system you may need to take the required registry view into account, in particular if you are installing a 32-bit application on a 64-bit system. Pay extra attention if all of the following are true:

You are installing a 32-bit application on a 64-bit Windows system; and
As part of your installer, you are explicitly creating one or more registry keys or values that are used by your application (registry values created by self-registering DLLs etc. may be ignored for this purpose); and
The registry keys or values that you create are subject to the 64/32 registry view distinction (this is only the case for some registry keys and values under HKEY_LOCAL_MACHINE).

To find out if condition #3 is true, start the Windows Registry Editor on a 64-bit system that has your application installed, and look for the HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node registry key branch. If your registry keys and values appear under this branch, then they were created under the 32-bit view of the registry and you must take special action to install them correctly.

Default installer actions

The default Tarma Installer 64/32-bit registry actions on 64-bit Windows systems differed in previous versions, as follows:

Tarma Installer version	Registry behavior on 64-bit Windows systems
QuickInstall 2.x	Always uses the 32-bit view.
ExpertInstall 3.x	Always uses the 32-bit view, except for some uninstaller information.
Installer 5.0, Installer 5.1	32-bit Setup stubs use the 32-bit view, except for some uninstaller information; 64-bit Setup stubs use the 64-bit view. See Setup stubs for details about the different Setup.exe versions provided with Tarma Installer.
Installer 5.2 and later	By default, uses either the existing key (64-bit or 32-bit, in that order), or the native view (64-bit on a 64-bit Windows system). However, you can specify any view; see Available registry view options below.

Available registry view options

As of Tarma Installer 5.2, you can specify the registry key behavior on 64-bit Windows versions (and to some extent on Windows 32-bit versions). The following registry view options are available in the Registry view attribute associated with each registry key.

Note: This behavior is independent of the Setup stub that your installer uses; it only depends on the target system: 32-bit Windows or 64-bit Windows.

Registry view option	32-bit Windows	64-bit Windows
Existing key, else Native	Always uses 32-bit registry	Checks 64-bit and 32-bit views (in that order) and uses the first that already contains the key. If neither does, uses the 64-bit registry.
Native only	Always uses 32-bit registry	Always uses 64-bit registry
64-bit, then 32-bit	Always uses 32-bit registry	Tries to use the 64-bit view first, followed by the 32-bit one if the 64-bit failed. Note: This option differs from Existing key, else Native in that it will not try the 32-bit registry view if the registry action succeeds in the 64-bit view, even if the key already exists in the 32-bit view.
64-bit only	Always fails	Always uses 64-bit registry
32-bit only	Always uses 32-bit registry	Always uses 32-bit registry

Should you install under Wow6432Node?

As an alternative to the registry views offered by Tarma Installer 5.2 and later, you may consider installing your 32-bit registry keys and values directly under HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node on a 64-bit Windows system. However, we advise against this for the following reasons:

Microsoft documentation states that the 64/32 -bit registry view is implementation-dependent and may change in future versions of Windows. Your installer might not be compatible with those future versions in that case. In contrast, Tarma Installer's Setup program uses documented registry flags to access the 64-bit and 32-bit registry views, which should be independent of any future implementation changes in Windows.
The Wow6432Node registry node does not exist on 32-bit Windows versions. The installer will still create the requested registry keys, but they will have no effect, or at least not the effect that you intended. In contrast, Tarma Installer's Setup program automatically falls back to the 32-bit registry view on 32-bit Windows versions.

What if you need both 64-bit and 32-bit versions of the same registry key or value?

If you need to install both 64-bit and 32-bit versions of the same registry keys or values (but perhaps with different data) on 64-bit Windows systems, then you must create two versions of the same named registry keys and values, and control them by separate components, as follows:

Create (or reuse) at least two components on the Features and Components project page. Set the Platforms... of the first component to include all the 32-bit and 64-bit platforms that you are interested in, and the Platforms... of the second component to all the 64-bit platforms (both x64 and IA64, if need be), but no 32-bit platforms.
Create the registry keys and values that you want to use for the 32-bit data. Set the Registry view attribute of each key to 32-bit only and assign each key and each value to the mixed 32/64-bit component that you created in step 1.
Create an identical set of registry keys and values that you want to use for the 64-bit data. Set the Registry view attribute of each key to 64-bit only and assign each key and each value to the 64-bit only component that you created in step 1.

With this configuration, both sets of registry keys and values will be installed (separately) on 64-bit Windows systems, but only the 32-bit set on 32-bit Windows systems.