georgemac510 / hyperledger

Hyperledger permissioned blockchain for enterprise applications.

Asset transfer basic sample

The asset transfer basic sample demonstrates:

• Connecting a client application to a Fabric blockchain network.
• Submitting smart contract transactions to update ledger state.
• Evaluating smart contract transactions to query ledger state.
• Handling errors in transaction invocation.

About the sample

This sample includes smart contract and application code in multiple languages. This sample shows create, read, update, transfer and delete of an asset.

For a more detailed walk-through of the application code and client API usage, refer to the Running a Fabric Application tutorial in the main Hyperledger Fabric documentation.

Application

Follow the execution flow in the client application code, and corresponding output on running the application. Pay attention to the sequence of:

• Transaction invocations (console output like "--> Submit Transaction" and "--> Evaluate Transaction").
• Results returned by transactions (console output like "*** Result").

Smart Contract

The smart contract (in folder chaincode-xyz) implements the following functions to support the application:

• CreateAsset
• ReadAsset
• UpdateAsset
• DeleteAsset
• TransferAsset

Note that the asset transfer implemented by the smart contract is a simplified scenario, without ownership validation, meant only to demonstrate how to invoke transactions.

Running the sample

The Fabric test network is used to deploy and run this sample. Follow these steps in order:

1. Create the test network and a channel (from the test-network folder).

   ./network.sh down
   
   ./network.sh up createChannel -c mychannel -ca
   

For javascript:

./network.sh deployCC -ccn basic -ccp ../asset-transfer-basic/chaincode-javascript/ -ccl javascript

2. Change directory to application-javascript

   cd ../asset-transfer-basic/application-javascript/

3. Set admin user:

Delete the wallet/ directory in application-javascript/

npm start Sign in admin admin

• This will give an error, but creates your admin password

4. Set new user

Click on the 3 lines at the top-right and go to Register.

Add a user name (in my case John), then choose Creator, then hit submit.

Go into wallet/ and create a new file user-password.txt. Copy and paste the privateKey from your user.id file into user-password.txt. Remove all instances of \r\n in the privateKey, then save the file.

Logout

5. Log into the app with your new username and password from user-password.txt

6. Click on 3 lines at the top-right again and choose Add asset. Fill in the data requested, upload vehicle image and hit submit. Your image will be uploaded to IPFS and will render when you click on All assets, then view next to the newly added asset.

General directions from Hyperledger Fabric samples

1. Deploy one of the smart contract implementations (from the test-network folder).

   # To deploy the TypeScript chaincode implementation
   ./network.sh deployCC -ccn basic -ccp ../asset-transfer-basic/chaincode-typescript/ -ccl typescript
   
   # To deploy the Go chaincode implementation
   ./network.sh deployCC -ccn basic -ccp ../asset-transfer-basic/chaincode-go/ -ccl go
   
   # To deploy the Java chaincode implementation
   ./network.sh deployCC -ccn basic -ccp ../asset-transfer-basic/chaincode-java/ -ccl java
   

2. Run the application (from the asset-transfer-basic folder).

   # To run the Typescript sample application
   cd application-gateway-typescript
   npm install
   npm start
   
   # To run the Go sample application
   cd application-gateway-go
   go run .
   
   # To run the Java sample application
   cd application-gateway-java
   ./gradlew run
   

Clean up

When you are finished, you can bring down the test network (from the test-network folder). The command will remove all the nodes of the test network, and delete any ledger data that you created.

./network.sh down