support for delta updates

[koehlma]

It would be nice if we could support efficient delta updates. To this end, we first need to define a proper artifact format (see issue #25). An artifact may then contain a delta encoding of a filesystem (e.g., in the VCDIFF or a similar format).

Design requirements:

• R1: There should be a mechanism to make sure that the blocks used from another filesystem indeed have the expected contents.

Design notes:

• While being an open standard with tool support (e.g., Xdelta), VCDIFF does not seem to have a built-in mechanism to check the integrity of copied blocks. We would need to somehow add this on-top, e.g., by computing the hash over the entire update and checking whether it matches our expectations.

Blockers:

• #25

[sergi0g]

Is there any timeline for this feature?

[koehlma]

There is no timeline yet. We may add this towards the end of the year, but I cannot promise anything right now.