I am a newbie and started learning dapp on ethereum. Up till now, I wrote smart contracts; created frontend with html, css and js; deployed smart dapp on either private network(geth, ganache) or rinkeby testnet. I connected directly to blockchain via (frontend)js which is loaded by html pages.
I want to write a dapp that is deployed on two blockchain one private and one public i.e., certain data will be stored on private and rest will be stored on a public chain. The dapp should connect to these blockchain from backend Not from frontend. I have looked on the internet and found some sample of connecting a dapp from backend(nodejs) but I cannot find anything related with multi blockchain dapp. As far as i know, we configure our smart contract deployment configuration in "truffle-config.js" file. Now i need one group of contracts to be deployed on private chain and another group of contracts to be deployed on a public chain. Note that both groups are part of same dapp. What I want to know is:
How should i design this(please explain folder structure and truffle-config.js for multi deployment) ?
Will there be two web3 objects in backend(nodejs) ?
Is there any open source dapp that uses multiple blockchain?