Research: Solo-Para-Bridge-POC

[cuteolaf]

For the cross chain communication required in M2, we will use Parity's solo-para-bridge.

So it is mandatory to have a clear understanding of the following problems.

• What are the main principles of Substrate bridges?
• What are the main components of a Substrate-to-Substrate bridge?
• How do they work together to build a bridge?
• How do off-chain workers work in the project?
• How do we send cross-chain messages in the runtime?

[Lord-Nymphis]

Which format are we using for cross-messages?

How do we check computational problems written in different blocks of FB, given asynchronous block creation between FB and HB different block time? (randomization of block which issuing checked_ example_ if last "FB block batch" checked was between FB block n.12 and FB block n.24; are we in current "FB block batch" randomizing check between block 24 to 36)?

[cuteolaf]

Nice catch, @Lord-Nymphis

• Which format are we using for cross-chain messages?
  AFAIK, we have two options available at the moment - Encoded calls and XCM.
  But support for XCM messages is under development, so I think we should use encoded calls.
• How to handle the different block times of HB and FB?
  https://github.com/paritytech/parity-bridges-common/blob/master/docs/messages-relay.html

In each FB block, we will submit the result and hash of computational works done to the heavy blockchain.

[Lord-Nymphis]

• I think that if Encoded calls is more supported / developed, we should use that.

• According to the repo https://github.com/paritytech/parity-bridges-common/blob/master/docs/messages-relay.html it shouldn't be a problem. But are we actually randomizing the block number in which a specific random math_problem to be double checked is taken from?
  (meaning, in the example, if last block of the "FB block batch" is 36 and last block of last "FB block batch" checked was 24, is any math_problem solved between block 25 and block 36 going to be checked? So the checked_problem could randomly be from FB block 25 ; 26; ... 27; ...; 35 or 36?)

[cuteolaf]

It's possible.

[Lord-Nymphis]

So we should do it