Features and Components

Feature tree The Features and Components page defines the physical (development) and logical (user-visible) organization of your product's contents in the installer. It also contains any merge modules that you have imported into your project.

Features are pieces of functionality that the customer can select or not select for installation. A feature can contain subfeatures in a hierarchical fashion; internally, a feature also contains the components that must be installed to provide the functionality that the feature offers.
Components are groups of installation items, such as files, shortcuts, registry settings, etc., that must be installed and removed together.
Assemblies are specialized components that define .Net or Win32 assemblies.
Merge modules are self-contained MSI databases that contain a group of components for use in an installer. Typically, merge modules are created by third-party developers to ensure that their products are correctly installed if you use them in your own product.

The Features and Components page has a tree view on the left and a list view on the right. The tree view contains the Features and Components tree plus the Merge Modules tree . The list view displays the contents of the currently selected tree view item.

Tip: You can use drag & drop to move features in the tree and to add components to features. You can also drag & drop objects from the list view of one component to another component in the tree view.

Example

Assume that you are designing an installer for a suite of office productivity tools. The suite might include a word processor, a database manager, and a spreadsheet. Each of those applications in turn may have one or more optional extras, such as content templates and additional help resources. The user may choose which tools to install (word processor, database, spreadsheet) and also which extras. Depending on the selected tools and extras, different sets of files and other items must be installed.

In your Tarma Installer project, this translates to features (shown as ) for each of the tools and extras, and components (shown as ) for each of the file sets.

In the installer, the features that you define for your product are visible as a tree of installation options; the branches of the trees (i.e., features and subfeatures) can be selected or not selected for installation. Components are not visible in the installer, but are present internally as part of the feature tree and selected with their parent feature.

Using Features and Components

Tarma installers have very relaxed rules for features and components. You can build a Tarma installer without using any features or components at all; in that case, there are no product options available (although the installation folder can still be selected by the customer) and all product contents are always installed. Most of the time, however, your Tarma installer will use some features and components, but Tarma imposes very few restrictions on the composition of your components.

However, you must use components in the following situations:

Platform-dependent files and items. If you have any files or other installation items that must be installed on some platforms (i.e., Windows versions) but not on others, then you must create a component for the items that are platform-dependent, set the component's Platforms option as required, and assign the files and other items to that component. See Component attributes for details.
Language-dependent files and items. If you have any files or other installation items that must be installed for some languages but not others, for example separate English, French and German versions of your software, then you must also create a separate component for each language or group of languages and use the component's Languages option as required. Again, see Component attributes for details.
Other conditional files and items. If there are other conditions that are not covered by the standard platform and language options, then you can use the component's Condition field to create a component that is subject to yet more checks at installation time, for example the presence of a special registry entry. You can use any conditional expression in the component's Condition field.

These options may be combined to create, for example, a component that is only installed during a French installation on a 64-bit Windows XP target system where a specific registry value is also present.

If you use components for any of these situations, then the component (and the installation items it controls) is installed if, and only if, all its platform, language, and free-form conditions are fulfilled, and its parent feature is selected for installation.

Using Assemblies

An Assembly represents either a .Net assembly or a Windows side-by-side assembly. Assemblies are specialized components, which means that they control the installation of the items that you put into them and are themselves subject to control by their parent feature. Assemblies differ from plain components in that an assembly can register itself on the target system as either a .Net assembly or a Windows side-by-side assembly.

See the following topics for information about assembly usage:

Tarma Installer's implementation of .Net and Windows side-by-side assemblies has one special feature: on Windows versions that do not support these assemblies, the files that make up the assembly are automatically redirected to the appropriate Windows System folder (32-bit or 64-bit). This allows some degree of backward compatibility and will allow most applications to operate correctly on older systems.

Merge modules

Although merge modules are MSI-based packages, you can use them for Tarma native installers. When you import a merge module into your project, Tarma Installer converts the MSI information in the merge module to Tarma's own project format; from then on, you can use the merge module's contents as you would any part of the project.

The merge module import typically results in the addition of a number of components to the product that are placed in their own feature (for easy of reference); any installation files in the merge module are automatically extracted and added to the project as well.

Tarma Installer 2.x upgrade notes

Tarma Installer 2.x did not use features or components; all product contents except shortcuts were always installed. However, it was possible in Tarma Installer 2.x to control installation of files and certain system settings by using a combination of language and platform options, and by using conditions.

In Tarma Installer, these options and conditions have moved to the component level. If you import a Tarma Installer 2.x project with any of these options into Tarma Installer, it will automatically create components that correspond to the various options. Wherever possible, files, registry settings, etc. that use identical options and conditions in the Tarma Installer 2.x project are assigned to the same component.