I have a simple question if i use
off chain workers to get calls to https://somecoinexchange/ to get data for
some calculation, what will be the
gas usage. I was presuming that since no chain work is done, no gas will be used.
FRAME doesn't use the concept of gas. It uses weight, which is currently determined based on running benchmarks on some standard hardware. However, everything that runs in
offchain_worker doesn't use any weight at all. The runtime code itself is seen as trusted code, but nodes are still allowed to opt-out from running
TDLR: Your assumption that no weight/gas is being used is correct.