Hyperledger Fabric Gateway SDK for Java

Note: this API is deprecated as of Fabric v2.5, replaced by the Fabric Gateway client API.

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).

    public static void main(String[] args) throws IOException {
        // Load an existing wallet holding identities used to access the network.
        Path walletDirectory = Paths.get("wallet");
        Wallet wallet = Wallets.newFileSystemWallet(walletDirectory);

        // Path to a common connection profile describing the network.
        Path networkConfigFile = Paths.get("connection.json");

        // Configure the gateway connection used to access the network.
        Gateway.Builder builder = Gateway.createBuilder()
                .identity(wallet, "user1")

        // Create a gateway connection
        try (Gateway gateway = builder.connect()) {

            // Obtain a smart contract deployed on the network.
            Network network = gateway.getNetwork("mychannel");
            Contract contract = network.getContract("fabcar");

            // Submit transactions that store state to the ledger.
            byte[] createCarResult = contract.createTransaction("createCar")
                    .submit("CAR10", "VW", "Polo", "Grey", "Mary");
            System.out.println(new String(createCarResult, StandardCharsets.UTF_8));

            // Evaluate transactions that query state from the ledger.
            byte[] queryAllCarsResult = contract.evaluateTransaction("queryAllCars");
            System.out.println(new String(queryAllCarsResult, StandardCharsets.UTF_8));

        } catch (ContractException | TimeoutException | InterruptedException e) {
This package provides the set of interfaces that enable a Java application to interact with a Fabric blockchain network.
This package provides the set of interfaces that enable a Java developer to extend the set of built in handlers for controlling gateway strategies.