Generic Runtime Interaction Traits

[gnunicorn]

When interacting with a running node, a client often wants to either read some state or sent extrinsic (transaction) to the chain. While the first is pretty easy and quick to do for offchain workers as well as clients via rpc, the latter becomes rather complicated quickly. In general the following three steps must be taken in order to be able to submit a valid extrinsic: 1. generate the extrinsic call with types and values; 2. put the correct extra data on it (e.g. Era) and; 3. sign it properly – all of which are highly dependent on the exact configuration the runtime runs with.

Many attempts have been taken to tackle this, coming from various parts of the system (subtx, desub, offchain worker signed submitter), it is time to consolidate these efforts into a single set of traits a runtime should implement or provide information about for a substrate chain to be able to generate the correct extrinsic in a generic manner.

refs #4954
refs #917