Template storing

[mame82]

A proper serialization mechanism for the state instance objects is needed, along with a proper storing mechanism for the serialized data

• should be used to store templates
• persistent storage (on SD card)
• has to sync FS as soon as data is written, because the situation of power loss is common (f.e. when powered by host USB and detached)
• as protobuf is already used to transfer data (gRPC), a method for storing serialized protobuf messages would be prefered

Candidates for serialization:

• protobuf
• JSON
• gob ??

Candidates for storage

• file based (not prefered, because of the need to manage multiple files with additional metadata)
• sqlite --> has to be checked for the "immediate FS sync" requirement

A database driven solution is preferred for the storage problem

[mame82]

Chosen database: https://github.com/dgraph-io/badger

• allows syncing DB writes to disk
• simple KV storage
• native Go implementation (no cgo)
• compatible license (Apache-2.0)

[mame82]

For encoding the gRPC protobuf encoding is used:
--> Only structs with protobuf support are valid for storing (this means every storeable type/struct should be defined in the proto file ;-))

[mame82]

Solved with badger and protobuf (only data defined in proto files is storable)