The Patch Existing File action allows you to compare the current version of a file with a previous existing file, generate a delta file as an update is being created, and then utilizing the delta file and the existing file to create the new file on deployed systems. This action utilizes the Microsoft Delta Compression API to generate the patch file, and re-create the new file starting from the existing file.
Prepare Stage
During the prepare stage, this action verifies permissions to the target folder.
Execute Stage
During the execute stage, the original existing file is backed up in case the update must be rolled back. The patch is then applied to the existing file. After the patch is applied, the hash of the resulting file is compared to the hash of the target file that was taken when the update was created. If the resulting file hash does not match, the action fails and a rollback is initiated.
Cleanup Stage
Removes the backup copies that were made during the execute stage.
Rollback Stage
Replaces the target file with the original back up created prior to performing the Execute stage.