I want to build a blockchain network such that if one node updates, all the other linked nodes gets update too. Think of it as Centralized Hospital record in multiple cities, if any of the city pushes the record it gets updated on each node. Any idea how to get started on that? I have pretty basic knowledge on building DAPP's any help will be highly appreciated, thanks.
closed as too broad by shane, Ismael, alberto, Majd TL, Sanjay S B Oct 3 at 6:25
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Well, that's what Blockchain does.
since you mentioned "Centralised" then probably you want to go with a private Blockchain, such as Hyperledger Fabric or sawtooth, R3 Corda, Quorum .... etc.
Hyperledger Fabric is the most popular, check out the doc to learn more: https://hyperledger-fabric.readthedocs.io/en/latest/
If you want an academic course about Blockchain, you can check out the Berkeley Courses https://blockchain.berkeley.edu/courses/
Here is a link of a collection of resources to help you learn blockchain: https://www.codementor.io/learn/blockchain
Hope this would help.
As stated in the comments this is basically what normal blockchains (including Ethereum) already do. All data is propagated to all connected nodes and all (full) nodes process all the information.
So what you need is a program inside the blockchain which retains your information - in Ethereum those are called smart contracts. Basically you upload your contract to the blockchain and different nodes push information (transactions) to the blockchain which update the contract's state (data). All nodes then process the information and see the same data.
For learning more about writing smart contracts I recommend CryptoZombies tutorial: https://cryptozombies.io/