I've been experimenting with downloading large files using the Download File plugin, for the purpose of supporting some new functionality in my installer. The plugin has a checkbox called "Allow resume broken downloads," with the following statement in the help file:
This would suggest that if a file being downloaded by Download File is interrupted (e.g. a network failure), then the file would be left partially downloaded at the target location (Local file path and name). However, this does not seem to be the case. I have run several tests downloading a 170 MB file, all with the box checked, which takes a little over 2 minutes to download. The file does not appear at the target location until the download has completed successfully. If I disable my network before the download is complete (I tried about 3/4 of the way through), the plugin returns with ERROR and the file never appears, partial or otherwise. If I then call the plugin again, using the exact same parameters, rather than taking only 1/4 of the total time (to resume the broken download), it took over 2 minutes, which suggests to me that the broken download wasn't resumed but restarted from the beginning.Local file path and name
Enter the full path for the local copy of the file on the target system. If file already exists, and the Allow resume broken downloads checkbox is checked, it will be assumed to be a previously broken download and the Download File command will attempt to resume the download from where it left off.
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Allow resume broken downloads
Check this checkbox to permit continuation of broken downloads. Uncheck it to always download files from the beginning.
1. Is there an undocumented setting somewhere that forces the Download File plugin to save and update the partial file to disk at the target location as it downloads (rather than only writing the complete file to the target location on SUCCESS)?
2. If so, will the file be left there on ERROR, or will it be automatically deleted as some browsers seem to do (e.g. IE, Chrome)?
3. Since the plugin doesn't create or leave partial files, what is the purpose of the "Allow resume broken downloads" checkbox? How can you resume something that doesn't exist because it is never written?