The Fabric Gateway SDK allows applications to interact with a Fabric blockchain network. It provides a simple API to submit transactions to a ledger or query the contents of a ledger with minimal code.
The Gateway SDK implements the Fabric programming model as described in the Developing Applications chapter of the Fabric documentation.
The following shows a complete code sample of how to connect to a fabric network, submit a transaction and query the ledger state using an instantiated smart contract (fabcar sample).
package org.example;
import java.nio.file.Path;
import java.nio.file.Paths;
import org.hyperledger.fabric.gateway.Contract;
import org.hyperledger.fabric.gateway.Gateway;
import org.hyperledger.fabric.gateway.Network;
import org.hyperledger.fabric.gateway.Wallet;
public interface Sample {
static void main(String[] args) throws Exception {
// Create a new file system based wallet for managing identities.
Path walletPath = Paths.get("wallet");
Wallet wallet = Wallet.createFileSystemWallet(walletPath);
// load a CCP
Path networkConfigPath = Paths.get("..", "..", "basic-network", "connection.json");
Gateway.Builder builder = Gateway.createBuilder();
builder.identity(wallet, "user1").networkConfig(networkConfigPath);
// create a gateway connection
try (Gateway gateway = builder.connect()) {
// get the network and contract
Network network = gateway.getNetwork("mychannel");
Contract contract = network.getContract("fabcar");
byte[] result = contract.submitTransaction("createCar", "CAR10", "VW", "Polo", "Grey", "Mary");
System.out.println(result);
result = contract.evaluateTransaction("queryAllCars");
System.out.println(new String(result));
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
git clone https://github.com/hyperledger/fabric-gateway-java.git
cd fabric-gateway-java
mvn install
The mvn install command will download the dependencies and run all the unit tests and scenario tests. It will also generate all the crypto material required by these tests.
All classes and methods have a high coverage (~90%) of unit tests. These are written using the JUnit framework
Scenario tests are written using the Cucumber BDD framework