Cumulocity IoT Feedback Portal
The download of binaries from the cumulocity platform does not support resuming already started downloads. If a device is switched off during a running download it will restart the download from the beginning when it starts again.
It would require to support the following headers to support the resume of downloads:
HEAD request to a binary URL returns the additional „Content-Length“ header which should be set to the filesize of the requested file in bytes. https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Length
When you then download a binary by a GET request it would require that the header „Range“ is supported which specifies the byte range which should be downloaded.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Range
As a result lot of traffic and bandwidth could be saved if downloads could be resumed, especially when there is a bad connection with a lot of interrupts.
With Cumulocity IoT 10.17 support for partial downloads for the binary API (https://cumulocity.com/api/core/#tag/Binaries) will be added.
Dear Christoph, thanks a lot for your feedback and apologies for the late response. We agree that supporting for partial downloads of software/firmware binaries is important and this is a request that we have also seen from other customers. As we currently have a very long backlog, we plan to implement support for partial downloads in one of the 2022 releases.