SmartContractTrading-wFabric1-4-VSCodeExt

SmartContract Trading using IBM Blockchain Platform Extension for VSCode (supports Fabric 1.4)

Welcome to Part 2 of building a Blockchain application using the IBM Blockchain Platform. This is a continuation of Create a Blockchain Network on IBP V2.0. You should be already familiar with setting up a network in VSCode or IBM Blockchain Platform from the previous pattern in this series. This pattern focuses on how you create a smart contract. The Smart Contract is at the heart of a blockchain network. It enables a participant to change the state of an asset. In this use case, the assets are Commodities and Traders and the participant is able to execute the following transactions or smart contracts: Trade or CheckQuantity. IBM Blockchain Platform Extension for VSCode makes it very easy to create and test out smart contracts. Let's give it a try.

When you have completed this code pattern, you will understand how to use the IBM Blockchain Platform Extension for VSCode to:

Create a smart contract
Package the smart contract
Install and instantiate a smart contract package
Test the smart contracts

Architecture flow

Setup and launch the VSCode Platform
Develop a smart contract using Node.js
Start a local instance of a Fabric Network within the VS Code Platform
Install and instantiate the smart contract
Test out the smart contract transactions

Included components

IBM Blockchain Platform Extension for VS Code is designed to assist users in developing, testing, and deploying smart contracts -- including connecting to Hyperledger Fabric environments.

Featured technologies

Hyperledger Fabric v1.4 is a platform for distributed ledger solutions, underpinned by a modular architecture that delivers high degrees of confidentiality, resiliency, flexibility, and scalability.
Node.js is an open source, cross-platform JavaScript run-time environment that executes server-side JavaScript code.

Prerequisites

Running the application

Follow these steps to set up and run this code pattern. The steps are described in detail below.

Steps

Install the prerequisites
Clone the repo
Edit package json file
Create the smart contract
Package the smart contract
Start the local network
Install and Instantiate the Smart Contract
Test the transactions

1. Install the Prerequisites

Ensure you have the following installed

Visual Studio Code
Visual Studio Code Extension

Navigate to the Visual Studio Code Extension marketplace page
Click Install
Restart Visual Studio Code to complete the installation of the extension

If you are using Windows, you must also ensure the following:

Your version of Windows supports Hyper-V and Docker:
Windows 10 Enterprise, Pro, or Education with 1607 Anniversary Update or later
Docker for Windows is configured to use Linux containers (this is the default)
You have installed the C++ Build Tools for Windows from windows-build-tools
You have installed OpenSSL v1.0.2 from Win32 OpenSSL
Install the normal version, not the version marked as “light”
Install the Win32 version into C:\OpenSSL-Win32 on 32-bit systems
Install the Win64 version into C:\OpenSSL-Win64 on 64-bit systems

You can check your installed versions by running the following commands from a terminal:

node --version
npm --version
docker --version
docker-compose --version

Once you have installed Visual Studio Code, the first thing you need to do is to install the IBM Blockchain Platform VSCode extension. To do this, you need to install the latest version of VSCode; to see if you have the latest VSCode extension, go to Code > Check for Updates. If VSCode crashes at this point, it likely means you don’t have the latest version. Update your VSCode, and once you’re done, click on extensions in the sidebar on the left side of your screen. At the top, search the extension marketplace for IBM Blockchain Platform. Click Install and then click reload. Now you should be all set to use the extension!

2. Clone the repo

Clone this repository in a folder of your choice

            `git clone https://github.com/IBM/SmartContractTrading-wFabric1-4-VSCodeExt.git`

3. Edit Package JSON File

The first thing you need to do is edit the Package.json file. In this file - you will need to state the name of the smart contract. In this instance we will call it auction.

You can also supply a description.

4. Create the Smart Contract

Recall from the intro that the Smart Contract defines the different states of an object or asset. Additionally, it governs the processes or transactions that can occur that moves the object between different states. Developers use smart contracts to define the key business processes and data that can be shared across organizations within a blockchain network.

The next task is to edit the provided smart contract and code up the transactions. A copy of this pattern's smart contract is contained in \contract\lib\auction.js. Take a look at it in more detail.

You will see that at the top of it, the requirement for the fabric contract API package and we are extending the contract class:

                 `class Auction extends Contract {`

The first function that is called when the smart contract is instantiated is called instantiate. Sometimes you will see developers call it init.

The next function CreateAssetsandMembers which will actually write data to the fabric network.

In this function, we are creating 2 instances of the Commodity asset (Gold & WonderDrug) and 2 instances of a Trader participant (SI1 and RT2). Note the example of creating an asset:

                 `var commKey = 'GOLD';
                 var commodity = { 
                   docType: 'commodity', 
                   description: 'Yellow Bars',
                   mainExchange: 'London',
                   quantity: 100,
                   owner: 'SI1'
                };`

The data being written to the ledger are created as JSON objects that are then 'stringified' with this command:

                `await ctx.stub.putState(commKey, JSON.stringify(commodity));`

We will add a checkQuantity function to query or read from the network. We will use the getState() method from the smart contract context to read the data and then pass in the output into a JSON object. This transaction function will take the Hyperledger Fabric context and one argument, commKey, which identifies which commodity to process the transaction against.

                `let commodityBytes = await ctx.stub.getState(commKey);`

The last thing we will do is execute a trade where a new owner gets assigned a new commodity. The logic requires you first read the data from the ledger, validate it and then a new block to the ledger assigning a new owner to the commodity. Assuming everything is valid, we will make the update using the putState method.

                 `await ctx.stub.putState(commKey, JSON.stringify(commodity));`

Voila' You have completed writing the smart contract.

5. Package the smart contract

Now that your smart contract is written - we need to install it and instantiate it on the network using the IBM Blockchain Platform VSCode Extension

If you didn't create the code inside of VSCode - you will need to add the contract folder into the tool. You will see this:

Note - it is important - if you get an error about not recognizing the programming language, ensure you only loaded the contract directory and not your whole github directory.

Click the IBM Blockchain Platform extension button (it looks like a square all the way on the bottom of the left sidebar). This will show the packaged contracts on top and the blockchain connections on the bottom.

Next, click on the 3 dots and select Package a Smart Contract Project. You will see the following once your project has been packaged.

6. Start the Local Network

Now you are ready to deploy to the local fabric network. Before you can install the smart contract on the network, you need to first connect to a network. The network that comes with the VSCode extension is perfect for development — it offers the minimal resources to develop and test your contract. The following Docker containers are started on your local machine, each with a different role in the network: Orderer, Certificate Authority, CouchDB, and Peer.

Click on the extension, you should see FABRIC ENVIRONMENTS on the left side of the editor. Under this section, you should see Local Fabric. Click it to start the Local Fabric.

Your extension will now provision those Docker containers that will act as nodes in your network. Once the provisioning is finished and the network is up and running, you will see this in VSCode:

7. Install and instantiate the smart contract

Now that the Fabric network is running, we need to install our smart contract onto the peer.

Install

In the FABRIC ENVIRONMENTS section near the bottom, click on Smart Contracts > Installed > Install. You will see a pop-up similar to the graphic below.

Then select the packaged contract: [email protected] Packaged Note The 0.0.1 comes from your package.json line: "version": "0.0.1"

After the install is complete, you should get a message Successfully installed on peer peer0.org1.example.com. You should also see that the contract is listed under Installed under FABRIC ENVIRONMENTS.

Instantiate

Under Smart Contracts you will see a section that says Instantiated. Click on + Instantiate under it.
The extension will then ask you which contract and version to instantiate — choose [email protected] Installed.
The extension will then ask you which function to call on instantiate — type in instantiate
Next, it will ask you for the arguments to the function. There are none, so just hit enter.
Next, the extension will then ask you do you want to use a provide a private data collection configuration file? - Click on no.
Lastly, the extension will then ask you do you want to choose a smart contract endorsement policy. Choose Default (single endorser, any org).

Once instantiation of thee contract completes, you should get the message Successfully instantiated smart contract and you should see [email protected] under Instantiated under FABRIC ENVIRONMENTS.

8. Test the transactions

You can test out the transactions right in the VSCode platform. Under the Fabric Gateways section, click on Local Fabric, then click on mychannel, then click on [email protected] - expand it to show the following:

Notice that all of the transactions that you created in the auction.js file are listed. If you right-click on the CreateAssetsandMembers transaction and then select Submit Transaction, a pop-up will come up. Hit return (don't enter any arguments). Hit return again (there is no transient data for the transaction), you should get a response that the transaction was successfully submitted.

At this point, you will have created the 2 instances of commodities and 2 instances of traders.

Now let's submit the checkQuantity transaction. As before, right-click on the the checkQuantity transaction and select Submit Transaction. This time you do have to enter an argument. Enter ["GOLD"] as the argument. Hit return. Hit return again (there is no transient data for the transaction). You should see the following response in your output window:

Now let's submit the trade transaction. Provide ["GOLD", "RT2"] as the list of arguments. Hit return. Hit return again (there is no transient data for the transaction). You should see the following response in your output window:

Extending the code pattern

You learned how to create, package, install, instantiate and invoke a smart contract using the VSCode Platform that supports IBM Blockchain Platform. If you want to extend this pattern:

You can leverage a network instantiated using the IBM Blockchain Platform Service along with IBM Cloud Kubernetes Service on IBM Cloud.
You can write a standalone application that executes the transactions. You can learn more about these extensions in the third pattern of this series. Emit events from Blockchain Platform
Create a wallet for every member and use the member's wallet to interact with the application.
Add a UI application in place of the invoke.js node application to execute the transactions.

License

This code pattern is licensed under the Apache Software License, Version 2. Separate third-party code objects invoked within this code pattern are licensed by their respective providers pursuant to their own separate licenses. Contributions are subject to the Developer Certificate of Origin, Version 1.1 (DCO) and the Apache Software License, Version 2.

Apache Software License (ASL) FAQ

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