Keeping *internal* API and ABI compatibility makes working with an already
complex codebase more mentally demanding than it needs to be.
Remember: plugins should be in-tree and upstream! If your out of tree plugin
stops working then it should be upstream.
The public-facing libfwupd will remain API and ABI stable for obvious reasons.
The former drags on glib-networking and then gsettings-desktop-schemas, which
add over 5Mb to the minimal IoT and CoreOS composes. Everything already uses
libcurl (even NetworkManager!) and so this is an easy way to reduce image size.
A Jcat file can be used to store GPG, PKCS-7 and SHA-256 checksums for multiple
files. This allows us to sign a firmware or metadata multiple times (perhaps
by the OEM and also then the LVFS) which further decentralizes the trust model
of the LVFS.
The Jcat format was chosen as the Microsoft catalog format is nonfree and not
documented. We also don't want to modify an existing .cat file created from WU
as this may make it unsuitable to use on Windows.
More information can be found here: https://github.com/hughsie/libjcat
