title: hyperledger: how to check authorization in the chaincode
body: <p>I have built a hyperledger chaincode for a blockchain service that contains all the regular init, invoke, read/write methods. However, to make it work in the real world, I need to add authorization check for which user can call which method. For example, user-A from peer-0 can call certain read/write while user-B from peer-1 can only call read.  I am not finding any examples so far, can someone please provide some example or guidelines on how to do that?</p>