purpose of offchain

Question

Hello Team,
1)What is the main purpose of offchain compared to onchain ?
2)Because as i learn about multichain offchain data i did not understand why it is creating binarycache. Is it for storing data in main chain when node is offline or disconnected to chain?
3) Also wanted to know can i implement it through nodejs api. It its avaiaible then please send me link for that.
 

Please help me to understand.

Advance thanks

Answer 1

The purpose of off-chain stream data is to allow larger amounts of data to be notarized on the blockchain (via hash/es) without every node needing to keep a copy of that data. There's an in-depth explanation here:

https://www.multichain.com/blog/2018/06/scaling-blockchains-off-chain-data/

The binary cache is just an efficient way to get large pieces of data into MultiChain, without having to send it in a single API request. It has no direct relationship to the on-chain vs off-chain question.

To use off-chain data you just need to add a single parameter to a regular publish API call, so if this is not currently supported by the Node.js library you are using, it should be easy to add.