Oneledger SDK

Oneledger SDK is a series of highly customizable JavaScript libs that allow developers to interact with Oneledger network.

SDK has several codebase that taking care of different features.

• ons-SDK: Main codebase of Oneledger SDK, including online queries, offline transaction serialization and useful tools with default config export.
• hd-vault: HD wallet core, including HD wallet generation, master key management, key pair derivation, transaction sign and address verification.
• ons-faucet: Oneledger testnet faucet, including CLI and request functions for minting OLT on Oneledger testnet.
• middle_utility: Middle layer helper lib, including all pre-defined error code and error message and common tools that all other Oneledger SDK libs are using.
• sdk-interoperability: Oneledger interoperability lib of SDK, including support of Ethereum and Bitcoin lock&redeem feature.
• explorer-sdk-js: Oneledger Explorer SDK, including APIs of Oneledger transactions queries from Explorer server.

For hackathon event, here are some info you will need in the SDK, and these will be explained in the following tutorial

1. fullnodeUrl: https://comm-test-fn1.devnet.oneledger.network/jsonrpc
2. faucetServerUrl: https://comm-test-faucet.devnet.oneledger.network/jsonrpc
3. CustomizedTxType: 990201
4. CustomizedRPCMethod: vpart_query.GetVPart
5. json tag for creating the transaction that insert vehicle part:

    VIN:                 "vin"
    Part Type:           "partType"
    Dealer Name:         "dealerName"
    Dealer Address:      "dealerAddress"
    Stock Number:        "stockNum"
    Year of Manufacture: "year"
    Operator:            "operator"
   

6. Some restrictions in the vehicle part tracking app:
   1. Vehicle identification number (VIN) needs to be exact 17 characters in string
   2. Stock number needs to be exact 9 characters in string
   3. The combination of VIN and part type should be unique(same VIN with different part types will be recognized as different vehicle part entities, vise versa)
   4. Year of manufacture will be integer
7. json tag for querying the vehicle part:

    VIN:                 "vin"
    Part Type:           "partType"
   

0. Pre-Start

Install npm and node and make sure you have them as the following version:

    $ npm -v
      6.14.7

    $ node -v
      v10.21.0

Create your own project:

    $ mkdir my_awesome_project
    $ cd my_awesome_project
    $ npm init

Just follow the default settings during npm init would be fine, you can always make changes in package.json about your project later.

Download Oneledger SDK libs (Click on zip file and click Download button) and update package.json dependencies:

    "dependencies": {
        "hd-vault": "file:./hd-vault", 
        "middle_utility": "file:./middle_utility",
        "ons-SDK": "file:./ons-SDK",
        "ons-faucet": "file:./ons-faucet",
        "explorer-sdk-js": "file:./explorer-sdk-js"
    }

All Oneledger libs should be stored under the root dir of your project.

Your root dir should look like below:

.
├── explorer-sdk-js
├── hd-vault
├── middle_utility
├── node_modules
├── ons-SDK
├── ons-faucet
└── package.json

Install dependencies:

Run below command inside each Oneledger SDK dependency folder, then run it one more time in your project root dir.

    $ npm i

Create main.js file, this would be the main file of your project:

    $ touch main.js

Declare some const values that we need in this project later:

    const yourMasterKeyPassword = "5h$mY_SupEr_sTRong_%$passWorD123#@"; // password to encrypt/decrypt your HD wallet master key, choose for yourself
    const fullnodeUrl = "https://comm-test-fn1.devnet.oneledger.network/jsonrpc" 
    // fullnode URL is used to broadcast transactions and make query, please refer to the beginning of this tutorial
    const faucetServerUrl = "https://comm-test-faucet.devnet.oneledger.network/jsonrpc"; 
    // faucet server URL is used to request Test OLT, please refer to the beginning of this tutorial
    const requestAmount = 10000; // Test OLT amount to request
    const sendAmount = "2000"; // Test OLT amount to send

Tips: you can always run your code by $ node main.js in terminal.

1. Create HD Wallet:

Import HD vault to your project, in main.js

    const HDVault = require('hd-vault');

Master Key Derivation:

    const mnemonicWords = HDVault.mnemonicUtil.mnemonicGenerator24();
    const masterKey = new HDVault.MasterKeySeedManager(mnemonicWords, yourMasterKeyPassword);
    const {encryptedMasterKeySeed} = masterKey.getMasterKeySeedInfo();

This step is only needed once, after you get your master key seed info, put it into a variable to be used later.

Now you have a functioning HD wallet yourself, you can derive Oneledger key pairs from your HD wallet now.
There are few things you need to keep in mind before proceeding:

1. Things you need to store somewhere safe and never share with anyone else:
   a). 24 mnemonic words(specific in given order), this is used to generate your master key.
   b). Your master key password, this is used to encrypt/decrypt your master key.
   c). Never share your master key info.
2. If you forget your password, you can always recover with your 24 mnemonic words(in given order).
3. If you forget password AND 24 mnemonic words, you lose the access to your wallet forever.
4. Different master key can derive different key pair even with the same key type and the same key index.
5. HD wallet is an independent module that is used for key pair derivation and transaction signing based on key type, we only need Oneledger key pair here, key type is OLT.

2. Create Oneledger Account

Oneledger Key Derivation

    const derivedKeyData = {
        keyType: "OLT",
        keyIndex: 0, // Increment keyIndex for generating new keys
        password: yourMasterKeyPassword,
        encryptedMasterKeySeed: yourEncryptedMasterKeySeed
    };
    const {response} = await HDVault.derivedKeyManager.deriveNewKeyPair(derivedKeyData).catch(error => {
        // handler error here
    });
    const {keyIndex, address, publicKey} = response;

Notice:

1. yourEncryptedMasterKeySeed is from the last step
2. keyIndex can be any non-negative integer, different keyIndex will derive different key pair.
3. For security reasons, HD wallet does not expose private key, the repsonse only returns current key index, address and public key associated with this address.
4. This address will be the operator field in the insert vehicle part transaction.

3. Request Test OLT

You can only request test OLT on Testnet or local blockchain network.

This is needed so we can have some balance to pay the transaction fee when we broadcast the transaction to the blockchain network.

    const faucet = require('ons-faucet'); 
    
    const env = {url: faucetServerUrl};
    const {response} = await faucet.requestOLT(address, requestAmount, env).catch(error => {
        // handle error here  
    });
    const result = response;

4. Prepare Transaction

Here, we are taking send currency to an address transaction as example.

    const {transfer} = require('ons-SDK');
    
    const env = {
        url: fullnodeUrl,
        storeConfig: {
            platform: "electron",
            storeLocation: __dirname
        }
    };

    async function sendToAddrOffline(fromAddress, toAddress, currency, sendAmount, env) {
        const sendToAddrPayload = {
            fromAddr: fromAddress,
            to: toAddress,
            amount: {
                currency: currency,
                value: sendAmount
            }
        };

        let responseSendToAddrTx = '';
        try {
            responseSendToAddrTx = await transfer.sendToAddressTxOffline(sendToAddrPayload, env)
        } catch (err) {
            // handle error here
        }

        const rawTx = responseSendToAddrTx.response.rawTx;
    }

Notice:

1. Oneledger SDK is designed as highly customizable, so that some configurations like storage solution can be decided by developers based on the platform they work on. To achieve that, all SDK request functions will take one param named env.

   You can always construct your own env object based on the Oneledger network you are connecting to, or the platform you are working on.

   For example, you can replace fullnodeUrl with the Oneledger fullnode url you are connecting to, by default SDK is pointing to Oneledger Mainnet.

   Oneledger SDK provides two kinds of config storage solution:
   a). electron: If you are working on electron app(or any other app that has access to the local file system), choose this one and set proper storeLocation, __dirname would be used by default.
   b). browser: If your are working on Chrome extension app(or any other app that has access to browser window.localSotrage), choose this one and set proper storeLocation, __dirname would be used by default.

2. currency here we use OLT.

3. Destructure the response to get rawTx, this is the transaction that you need to sign with your OLT key later.

If you are working on customized transaction, please go to 8. Customized Transaction in SDK

5. Sign Transaction

Sign transaction with Oneledger Key derived by HD wallet.

    const signData = {
        message: rawTx,
        keyType: "OLT",
        keyIndex: 0,
        password: yourMasterKeyPassword,
        encryptedMasterKeySeed: encryptedMasterKeySeed
    };
    const {response} = await HDVault.derivedKeyManager.signTx(signData).catch(error => {
        // handler error here
    });
    const {signature} = response;

Notice:

1. rawTx in the payload should be a Base64 encoded string, which you get from transaction prepare step.
2. keyIndex here indicates which key you want to use for signing.
3. You need to pass correct master key password to authorize HD wallet for signing.
4. signature in return response will be used for broadcast later.

6. Broadcast Transaction

    const {request, requestConfig} = require('ons-SDK');

    async function broadcastTx({publicKey, rawTx, signature}, env) {
        const broadcastBody = {
            broadcastType: requestConfig.BroadcastType.Sync,
            rawTx: rawTx,
            signature: signature,
            publicKey: {
                keyType: requestConfig.PublicKeyTypes.publicKeyType,
                data: publicKey // Make sure you use the publicKey here that derived from the same KeyIndex that used to sign your transaction.
            }
        };
        const {response} = await request.broadcastTx(broadcastBody, env).catch(error => {
           // handler error here
        });
        const {txHash, height} = response;
    }

If this function is called, you will see similar result as below:

{ response:
   { txHash:
      '0x64B3AADE349775974A3FFA9927C732669566EFA673954241A4A3AA3B84256D96',
     height: undefined } }

Notice:

1. broadcastType could be Async, Sync and TxCommitMtSig, we recommend to use Sync here.
2. publicKey.keyType should always be requestConfig.PublicKeyTypes.publicKeyType which is ed25519.
3. publicKey is the public key of the key pair that used to sign this transaction.
4. txHash in return response could be used for later tx query, each tx has its own unique txHash, height might be undefined if tx been broadcasted by Sync.
5. To successfully broadcast a transaction to Oneledger network, you should have enough OLT balance in the signing account, to get test OLT, please refer to 3. Request Test OLT

7. Query Account Balance

    const {request} = require('ons-SDK');

    async function queryBalanceForAddr({address, currency}, env) {
        const queryBalanceObj = {
            address: address,
            currency: currency
        };
        const {response} = await request.queryCurrencyBalanceForAccount(queryBalanceObj, env).catch(error => {
            // handle error here
        });
        const balance = response;
    }

Notice:

1. currency is optional, it will query all currency that address owns if currency not given.

8. Customized Transaction&Query in SDK

In this section, you will learn how to implement your own transaction and query in Oneledger SDK.

8.1 Prepare customized transaction type

    const CustomizedTxType = "YourTransactionType";

YourTransactionType must be registered on Oneledger protocol already, otherwise Oneledger blockchain will not recognize it.

This should be a six-digit number starting with 99. This is provided in the beginning of this tutorial.

8.2 Implement customized transaction prepare function

In main.js of your project.

    const {request, util, offlineSerialize} = require('ons-SDK');
    const {ErrorUtil} = require("middle_utility").TierError;

    const env = {
        url: fullnodeUrl,
        storeConfig: {
            platform: "electron",
            storeLocation: __dirname
        }
    };

    async function youCustomizedTx({youParameters, gasAdjustment = 0}, env) {
        // do the input check
    
        // query current gas price from Oneledger network
        let gasPrice;
        try {
            const result = await request.queryGasPrice(env);
            gasPrice = result.response
        } catch (err) {
            return Promise.reject(err)
        }
        
        // construct your customized transaction data
        const tx_dataObj = {
            // `fieldName` has to be explicitly defined in the customized transaction in Oneledger protocol as json tag name, in the vehicle part tracking app, this will be `vin` and so on.
            fieldName: parametersYouWantToPassHere 
            ...
        };

        const assembledTx = util.assembleTxData(CustomizedTxType, tx_dataObj, gasPrice, gasAdjustment);
        assembledTx.fee.gas = 400000
        const {gas} = assembledTx.fee;
        const feeEstimationResult = await util.txFeeEstimator(gas, gasPrice).catch(error => {
            return Promise.reject(error)
        });
        return Promise.resolve(ErrorUtil.responseWrap({...util.rawTxStructure(offlineSerialize.jsonObjectToBase64(assembledTx)), ...{feeEstimation: feeEstimationResult.response}}))
    }

Notice:

1. Oneledger SDK is able to support different type of transactions by different implementation of transaction prepare. Transaction prepare step will gather all data which transaction needed and encode it into rawTx.
2. gasAdjustment is used for providing more gas to speed up your transaction, it's 0 by default, we don't need to modify it.
3. youCustomizedTx defined above will return you rawTx along with feeEstimation which gives you a heads-up about how much the transaction fee is gonna cost.
4. After your get rawTx, you can continue from 5. Sign Transaction.

8.3 Customized Query in SDK

In this section, you will learn how to implement your own query in Oneledger SDK.

In main.js of your project.

    const {request} = require('ons-SDK');
    const env = {
        url: fullnodeUrl,
        storeConfig: {
            platform: "electron",
            storeLocation: __dirname
        }
    };
    async function queryValue(youParameters, env) {
        // `fieldName` here needs to be be explicitly defined in Oneledger protocol as json tag name, this is provided in the beginning of this tutorial, it should be `vin` and so on.
        const params = {
            fieldName: parametersYouWantToPassHere
            ...
            } ;
        //this custom method needs to be explicitly registerd in Oneledger protocol, this provided in the beginning of this tutorial
        const method = "YourCustomizedRPCMethod";
        const result = await request.queryCustom(method, params, env).catch(err => {
            // handle error here
            return Promise.reject(err)
        })
        return Promise.resolve(result)
    }

To Learn more about Oneledger SDK, please go to Full Documentation.