Cold chain smart contract

The purpose of this smart contract is for a cold chain deliveries tracker. It's completely developed in RUST.

Considerations

This is a project done in a UNIX-based system, as linux or MacOS.

If you are running Windows consider to install WSL for command terminal.

How to run the smart contract

First is required to compile the smart contract into binaries

./build.sh

In my case i needed extra permissions, so i give them to the file.

chmod +x ./build.sh

After use the near dev-deploy command and indicate where is your .wasm file. You can also use near deploy if you prefered to have it mainnet. Note: If permissions required write the following

near dev-deploy --wasmFile res/ncd_playground.wasm

Cold chain tracking

Imagine you are a want to send a cold chain package.

• Pay 10 NEAR for a new delivery for starting it, select the account to pay when the delivery is done.
• Record temperature in each arrival to a new location.
• Once the delivery is in the last location, withdraw 10 NEAR as payment for completing succesfully the delivery.
• Restart the cycle.

Also you can:

• Check the status of the contract if it is initialized.
• Get extra information of delivery (Truck plate, trucker name, temperature in ºF, fuel level, etc.)
• If the Temp goes out of range the payment is canceled and returned to smart contract.
• To start a new contract you need to pay the truck owner when you return to the origin

Locations (Simulated)

• 0 Tepic, Nayarit (Origin)
• 1 Guadalajara, Jalisco
• 2 Aguascalientes, Aguascalientes
• 3 Leon, Guanajuato
• 4 Ciudad de México (Destiny)

Note: We had de idea to do a get_location_verbose about this in the smart contract but we think was senseless and we could do that in frontend.

Deploy the smart contract inside the testnet

near dev-deploy --wasmFile res/ncd_playground.wasm

Note It can be required to delete this files to run correctly the SC

source neardev/dev-account.env 

echo $CONTRACT_NAME

Define your account inside your environment

export MY_ACCOUNT='mytest.testnet'
echo $MY_ACCOUNT

Commands in the smar contract

You can verify the status of the contract about a delivery by using get_initilized()

near call $CONTRACT_NAME get_initialized --accountId $MY_ACCOUNT

A new delivery will start using new_delivery(), you need to send 10 NEAR (--amount 10) and a JSON with the initial Temperature (ºC) and the account that will withdray the 10 NEARS if the delivery finish succesfully

near call $CONTRACT_NAME new_delivery '{"temp_c": -4.0, "payment_account_id": "alan1.testnet"}' --accountId $MY_ACCOUNT --amount 10

Creat a new arrival to a new location, temperature is saved.

near call $CONTRACT_NAME new_arrival '{"temp_c": -8.9}' --accountId 'alantest.testnet'  

If delivery is succesful, withdraw can be done and would be send to the account defined in new_delivery()

near call $CONTRACT_NAME withdraw --accountId $MY_ACCOUNT

JUST FOR DEBUG, decrement the location index, and reset the location index to 0.

near call $CONTRACT_NAME decrement --accountId $MY_ACCOUNT
near call $CONTRACT_NAME reset --accountId $MY_ACCOUNT 

Other commands inside the contract

Get location, range 0-4, 0 is origin and 4 is destiny.

near call $CONTRACT_NAME get_location --accountId $MY_ACCOUNT   

Get balance of smart contract, returns the balance in yocto.

near call $CONTRACT_NAME get_balance --accountId $MY_ACCOUNT    

Get temperatue, returns temp in a floating number.

near call $CONTRACT_NAME get_temp --accountId $MY_ACCOUNT    

Get payment account id (payment.test/payment.near)

near call $CONTRACT_NAME get_payment_account_id --accountId $MY_ACCOUNT  

Get initialized, returns a boolean.

near call $CONTRACT_NAME get_initialized--accountId $MY_ACCOUNT  

Testing the contract

Use cargo for running tests inside the contract

cargo test 

Wireframing

Figma link: https://www.figma.com/file/w4YSyB4ML1wtcSy6IueL9j/Cold-chain-Wireframe?node-id=1392%3A1130

Loom video

Video demo: https://www.loom.com/share/7ef30fb4deaf4088aad42600992dff97

What to do next? Some ideas for improving the code

In this ideation section, we give some items that could improve the code, but time in NCD bootcamp was not enough to do that.

• Add extra information about the delivery to be tracked (Truck plate, Driver ID, fuel level, etc.)
• Have multiple deliveries running at the same time in the smart contract.
• Define custom payment amount for delivery.
• Define a safe range for temperature, if it is out of range return the money.

Credits

This projects recovers ideas from many repositories, a list of those i remember. -https://github.com/near/core-contracts -https://github.com/near-examples/rust-status-message -https://github.com/Learn-NEAR/NCD-08--Communite/blob/master/assembly/index.ts