Lecture 4 -Looking deep into smartcontrats and other associated issues

Question 1

Name some of the things that Smart contracts enable

Answer 1

• Support data update and/or complex code rules.
• Responsible for processing transaction requests
• Determines transaction validity by executing business logic.

Question 2

Explain how you understand smart contracts

Answer 2

I see smart contracts as being APIs and defining the assets/data that the APIs interact with. (Database ORM and API in one)

Question 3

There are two types of smart contracts. What are they, and how do they differ?

Answer 3

• Installed smart contracts: install business logic on validators before network is launched.
• On-chain smart contracts: deploy business logic as a transaction committed to blockchain and then called by subsequent transactions.
  
  • Code that defines business logic becomes part of ledger.

Question 4

What’s the difference between chaincode and smart contracts?

Answer 4

Chaincode aims for permissioned smart contracts.
• Ethereum‘s smart contract offers a set of rules to build public smart contracts (builds for ICOs and public digital payment systems).
• Hyperledger and Ethereum are different in terms of privacy, decentralization, coding languages, involvement of cryptocurrency, and consensus mode used.
• Ethereum an edge over Hyperledger for applications requiring a payment instrument.

Question 5

What is meant by “Atomic transactions”?

Answer 5

• A transaction cannot be partly completed (ensures transaction integrity).
• Dependencies between multiple transactions can be specified.

Question 6

Because smart contracts are programs, they are subject to the following issues:

Answer 6

Syntax errors, Logic errors, malicious attack, coding errors, and poor design.

Furthermore:
Denial-of-Service (DoS) attack: resource become unavailable due to overloading.

If poorly designed, they can use excessive resources

Question 7

What is meant by endorsement policy?

Answer 7

Endorsement Policies:
• Describes endorsement policies before network start operations.
• Identifies which organizations must approve as valid transactions generated by smart contract.
• Each smart contract is deployed with an endorsement policy.
• A transaction can only be considered valid if it has been endorsed according to its policy

Question 8

Smart contracts in HLF is written in

Answer 8

Go, Javascript, or others

Question 9

Smart contracts in Ethereum are (typically) written in

Answer 9

Solidity

Question 10

What are NFTs

Answer 10

Unique and indivisible blockchain-based tokens introduced in late 2017.
• Every NFT is unique, and it cannot be divided or merged
• NFT improves tokenization of individual assets which is not feasible with fungible
tokens, as they cannot digitally represent uniqueness.
• NFTs were created to represent ownership over digital or physical assets.
• ERC-721 standard specifies that every NFT has a globally unique id, is transferable, and can optionally include metadata.
• Erc-20: a class of identical tokens (FT)