For products that install modules as shared components (modules that are used by multiple components of a product or by multiple versions of a product), install the modules in the Common Files folder along with other shared components. For example, suppose that Fabrikam has a binary module for its product. After you install multiple versions of the product, the value of the PSModulePath variable might resemble the following value:

$Env:PSModulePath = "C:\Users\username\Documents\WindowsPowerShell\Modules;C:\Windows\System32\WindowsPowerShell\v1.0\Modules;C:\Program Files\Common Files\Fabrikam\Modules"

The file structure might resemble the following file structure. Note that the common "Modules" folder contains a subfolder for each module.

C:\ProgramFiles
    CommonFiles
        Fabrikam
            Modules
                Fabrikam8
                    Fabrikam8.psd1 (Manifest file)
                    FabrikamCmdlets.dll (assembly)
                Fabrikam9
                    Fabrikam9.psd1 (Manifest file)
                    FabrikamCmdlets.dll (assembly)

For products that do not treat their modules as shared components, or if the modules have the same names, design the modules so that the user can specify the Version parameter when running the Import-Module cmdlet to force a particular module version to be imported. In this case, the value of the PSModulePath variable might resemble the following value:

$Env:PSModulePath = "C:\Users\username\Documents\WindowsPowerShell\Modules;C:\Windows\System32\WindowsPowerShell\v1.0\Modules;C:\Program Files\Fabrikam\Fabrikam8;C:\Program Files\Fabrikam\Fabrikam9"

The file structure might resemble the following file structure. Note that in this case, separate module folders exist for each version of the Fabrikam product so that the PSModulePath variable contains paths to the module folder of each version.

C:\ProgramFiles
    Fabrikam
        Fabrikam8
            FabriKamModule
                FabrikamModule.psd1 (Manifest file: ModuleVersion = “8.0”)
                FabrikamCmdlets.dll (assembly)
        Fabrikam9
            FabrikamModule
                FabrikamModule.psd1 (Manifest file: ModuleVersion = “9.0”)
                FabrikamCmdlets.dll (assembly)

In both of the previous scenarios, the user could have version 8, version 9, or both versions loaded in a Windows PowerShell session by running either or both of the following commands:

Import-Module FabrikamModule –Version8

Import-Module FabrikamModule –Version9

To handle the conflicts that can occur when modules import multiple elements that have the same name, the Prefix parameter of the Import-Module cmdlet can be used to add version number prefixes to the elements when they are exported. If prefixes are not added, the default behavior is to let the last exported element overwrite the previous element.

Version numbers can be added to module names if the module name matches the major version number of a product. For example, Fabrikam8Module and Fabrikam9Module work well for the Fabrikam 8.0 and Fabrikam 9.0 products. However, putting the version in the module name may not be appropriate when only the minor version number of the product changes, such as Fabrikam8.1Module and Fabrikam8.2Module.

Concepts