Does your installation have specific requirements before the installation executes, such as the existence of a specific operating system or the installation of another application? By creating launch conditions, you can specify certain requirements for your installation. Launch conditions are system requirements that your installation needs to run successfully. If the requirements are not met, your installation displays a message to the user and then terminates.
You can easily specify the following system requirements by using the System Requirements page in Installation Expert
Windows NT Version
Internet Explorer Version
Windows Installer Runtime Version
To create additional system requirements, you can search the system and use the result to set a launch condition. For example, your application requires that the software, RequiredApplication, needs to be installed on the destination computer. Due to this requirement, your installation verifies if RequiredApplication is installed. If RequiredApplication is not on the computer, a message appears that states the requirements are not met, and then the installation is aborted.
Before modifying your installation, establish a registry key or file that is unique to RequiredApplication. To determine if RequiredApplication is installed, the installation searches for this file or registry key. The following steps demonstrate how to create a search using the System Search page in Installation Expert. You can then use that search to create a launch condition.
In the following procedure, you will search for the registry value InstallationPath in the registry key HKEY_LOCAL_MACHINE\Software\RequiredApplication. If the search locates this registry key, the installation recognizes that RequiredApplication installed on the destination computer.
To create a system search:
This search sets the criterion that determines whether the installation continues or aborts. Now, you add a launch condition based on this search result. To create a launch condition:
Note: When populating the condition field of the dialog be sure to "List the condition that has to be met for your installation to 'continue' and the error message that appears when the condition is 'not met'.
Note: Do not add the property that you entered in the Read Registry Value dialog (SEARCHRESULTS) to the Property table. If you do add the property to this table, it always has a value since the property was created during design time. This causes the condition to always be true even if the launch condition is not met.
By default, the AppSearch action appears after the LaunchConditions action, which evaluates each launch condition added on the Product tab in Setup Editor. Because the AppSearch action performs the searches created on the System Search page, this action needs to occur before the LaunchConditions action. The following procedure lets you modify the sequence of these actions.
To modify the LaunchConditions action sequence:
Note: If your .MSI supports silent installation, complete these steps in the Execute Immediate sequence. During a silent installation, the User Interface sequence does not execute.
By creating a launch condition based on a system search, you have the ability to control whether an installation runs or aborts based upon system requirements. Launch conditions save time in troubleshooting, eliminates unnecessary aborted installations, and gives you greater control over the installation.