Differential Releases

InstallShield 2013

Project: This information applies to InstallScript projects.

In an InstallScript project, you can define and build a differential release—that is, a release that contains the files that are absent from—and/or have a different date, time, size, or attribute than the version in—one or more of a specified set of existing releases. A differential release is used to update the versions of your product that were installed by those existing releases. This type of upgrade also includes all of the maintenance/uninstallation feature’s files. The new versions of Data1.hdr, Data1.cab, and Layout.bin do not overwrite the existing versions but are placed in a new folder.

Note: Since a differential release consists of only the changed files between the specified existing media and the new media, installing a differential release on a system that does not have a specified earlier version of the product would most likely not produce a valid application. To update a system that does not have an earlier version of the product, create a full release.

Files Included in a Differential Release

When you define a differential release, you specify one or more existing releases to which the current project should be compared when new differential release is created. You specify these existing releases in the Update panel of the Release Wizard. A file in the current project is included in the differential release if any of the following are true:

The file is absent from—or has a different date, time, size, or attribute than the copy in—at least one of the specified comparison releases.
The file is in a component whose Difference property is set to Include Always.
The file is in a component that is absent from at least one of the specified comparison releases.
The file is in a component whose name is different in at least one of the specified comparison releases.
The file is in a component whose Destination, Languages, or Operating Systems properties are different in at least one of the specified comparison releases.
The file is in a component that is associated with a feature whose name or path within the feature hierarchy is different in at least one of the specified comparison releases.

Installing a Differential Release

When an installation initializes and the ADDREMOVE system variable is nonzero, the installation automatically attempts to initialize any differential releases that have been installed with the same product code. The installation enumerates all subfolders of the DISK1TARGET folder and searches these subfolders for differential releases; a differential release is found and loaded if all of the following conditions are met:

The subfolder contains a Data1.hdr file that is a valid InstallShield X or later, InstallShield DevStudio 9, or InstallShield Professional 6 or later Data1.hdr file for a differential release.
The product code stored in the header file matches the product code of the installation.
The product version of the differential release is newer than the product version of the installation.

See Also