This slide contains a bunch of screenshots for my linkedin article.

1. Locate to hello contract directory provided by eos

2. The source code of hello contract

3. Compile the contract & generate the abi

4. Create the hello account

5. Deploy the hello contract

6. Run the contract

7. Switch to the nodeos server to see the contract output

8. Modify the contract to add a line for user authentication

9. Re-deploy & run the modified contract. Now the ‘hi’ action failed

10. Run the contract with the permission of tester. It works

11. Terminate the keosd & nodeos servers before exit