CS61065 Assignment 2- Ethereum Basics Solution

Assignment 2: Ethereum Basics
In this assignment you will get familiar with the basics of Ethereum. You will learn how to connect to the Ethereum main network, access test networks, manage your accounts and execute transactions. You will also get started with Ethereum JavaScript API (web3.js) and do some basic operations in the test networks.
Submission Instructions
Submit the answers to the questions of Part A and Part B in the following google forms link: https://forms.gle/rNgESTWMcqSw3izQ8
Part A
We recommend you install Geth by following the instructions in the documentation page, and try it out: https://geth.ethereum.org/docs/install-and-build/installing-geth
For the rest of the assignment, create an account in https://infura.io/ , and use it to connect to the goerli test network.
Infura provides you JSON-RPC over HTTP interface. Use JSON-RPC calls to answer the following questions in the google form link provided above. Provide the (a) the answer, (b) the JSON payload used in the JSON-RPC, and (c) the response from the RPC call for each question.
[Note: each question will need a single RPC call only] A.0. Query the latest block number (converted to decimal).
Sample Answer:
a. 7527989
b.
{
"jsonrpc":"2.0",
"method":"eth_blockNumber",
"params":[],
"id":1
}
c.
{"jsonrpc":"2.0","id":1,"result":"0x72de35"}
A.1. Query the current gas price in wei. Give the answer as an integer (not in hex).
A.2. Find the number of transactions in the block with hash:
“0x78f20591bc53a4a06d28cc3a841608dc8637e669999f9cc854addd0a66024e78”. Give the answer as an integer.
A3. Query transaction receipt for the transaction with hash
“0x4210f581dda42ea2a2676fefa9edf784095a30ae2b49920e0965588d8fa78bf9”. Find out
(i) the blockNumber (integer),
(ii) blockHash,
(iii) cumulativeGasUsed (integer),(iv) transactionIndex (integer).
A.4. Find the number of peers connected currently to your Geth client (in infura).
A.5. Get the balance of the account “0x35F18427567108F800BDC2784277B9246eED37fA”. Answer in integer (wei).
A.6. Find the hash of the transaction in block number 5417322, at index 1.
Part B
Use the Goerli faucet (https://faucet.goerli.mudit.blog/) to obtain some ethereum in your account.
Use web3.js to query and execute the following smart contract:
Smart Contract Address: 0x709830edf8feF92B0d879dE9ee9BdB2400BB5662
The smart contract stores your roll number corresponding to your ethereum account address. Generate the ABI from the contract code. The code of the contract is as follows:
contract AddressRollMap {
mapping(address => string) public roll;
function update(string calldata newRoll) public {
roll[msg.sender] = newRoll;
}
function get(address addr) public view returns (string memory) {
return roll[addr];
}
function getmine() public view returns (string memory) {
return roll[msg.sender];
}
}
B.1. Query the roll for the address:
0x8AF72Ec4f53704FfF24737f0445ddB40483eebd1
B.2. Input your own roll through the update function. Submit your ethereum account address from which you made the transaction, and the transaction id.