Webuj is a lightweight, highly modular, reactive, type safe Java and Android library for working with Smart Contracts and integrating with clients (nodes) on the HappyUC network:

This allows you to work with the HappyUC blockchain, without the additional overhead of having to write your own integration code for the platform.

The Java and the Blockchain talk provides an overview of blockchain, HappyUC and Webuj.

• Complete implementation of HappyUC's JSON-RPC client API over HTTP and IPC
• HappyUC wallet support
• Auto-generation of Java smart contract wrappers to create, deploy, transact with and call smart contracts from native Java code (Solidity and Truffle definition formats supported)
• Reactive-functional API for working with filters
• HappyUC Name Service (ENS) support
• Support for Parity's Personal, and Ghuc's Personal client APIs
• Support for Infura, so you don't have to run an HappyUC client yourself
• Comprehensive integration tests demonstrating a number of the above scenarios
• Command line tools
• Android compatible
• Support for JP Morgan's Quorum via Webuj-quorum

It has five runtime dependencies:

• RxJava for its reactive-functional API
• OKHttp for HTTP connections
• Jackson Core for fast JSON serialisation/deserialisation
• Bouncy Castle (Spongy Castle on Android) for crypto
• Jnr-unixsocket for *nix IPC (not available on Android)

It also uses JavaPoet for generating smart contract wrappers.

Full project documentation is available at docs.Webuj.io.

You can help fund the development of Webuj by donating to the following wallet addresses:

Commercial support and training is available from blk.io.

A Webuj sample project is available that demonstrates a number of core features of HappyUC with Webuj, including:

• Connecting to a node on the HappyUC network
• Loading an HappyUC wallet file
• Sending Huc from one address to another
• Deploying a smart contract to the network
• Reading a value from the deployed smart contract
• Updating a value in the deployed smart contract
• Viewing an event logged by the smart contract

Add the relevant dependency to your project:

Java 8:

<dependency>
  <groupId>org.Webuj</groupId>
  <artifactId>core</artifactId>
  <version>3.3.1</version>
</dependency>

Android:

<dependency>
  <groupId>org.Webuj</groupId>
  <artifactId>core</artifactId>
  <version>3.3.1-android</version>
</dependency>

Java 8:

compile ('org.Webuj:core:3.3.1')

Android:

compile ('org.Webuj:core:3.3.1-android')

Start up an HappyUC client if you don't already have one running, such as Ghuc:

$ ghuc --rpcapi personal,db,huc,net,web3 --rpc --testnet

Or Parity:

$ parity --chain testnet

Or use Infura, which provides free clients running in the cloud:

Webuj web3 = Webuj.build(new HttpService("https://ropsten.infura.io/your-token"));

For further information refer to Using Infura with Webuj

Instructions on obtaining Huc to transact on the network can be found in the testnet section of the docs.

To send synchronous requests:

Webuj web3 = Webuj.build(new HttpService());  // defaults to http://localhost:8545/
Web3ClientVersion webuClientVersion = web3.webuClientVersion().send();
String clientVersion = webuClientVersion.getWeb3ClientVersion();

To send asynchronous requests using a CompletableFuture (Future on Android):

Webuj web3 = Webuj.build(new HttpService());  // defaults to http://localhost:8545/
Web3ClientVersion webuClientVersion = web3.webuClientVersion().sendAsync().get();
String clientVersion = webuClientVersion.getWeb3ClientVersion();

To use an RxJava Observable:

Webuj web3 = Webuj.build(new HttpService());  // defaults to http://localhost:8545/
web3.webuClientVersion().observable().subscribe(x -> {
    String clientVersion = x.getWeb3ClientVersion();
    ...
});

Note: for Android use:

Webuj web3 = webujFactory.build(new HttpService());  // defaults to http://localhost:8545/
...

Webuj also supports fast inter-process communication (IPC) via file sockets to clients running on the same host as Webuj. To connect simply use the relevant IpcService implementation instead of HttpService when you create your service:

// OS X/Linux/Unix:
Webuj web3 = Webuj.build(new UnixIpcService("/path/to/socketfile"));
...

// Windows
Webuj web3 = Webuj.build(new WindowsIpcService("/path/to/namedpipefile"));
...

Note: IPC is not currently available on Webuj-android.

Webuj can auto-generate smart contract wrapper code to deploy and interact with smart contracts without leaving the JVM.

To generate the wrapper code, compile your smart contract:

$ solc <contract>.sol --bin --abi --optimize -o <output-dir>/

Then generate the wrapper code using Webuj's Command line tools:

Webuj solidity generate /path/to/<smart-contract>.bin /path/to/<smart-contract>.abi -o /path/to/src/main/java -p com.your.organisation.name

Now you can create and deploy your smart contract:

Webuj web3 = Webuj.build(new HttpService());  // defaults to http://localhost:8545/
Credentials credentials = WalletUtils.loadCredentials("password", "/path/to/walletfile");

YourSmartContract contract = YourSmartContract.deploy(
        <Webuj>, <credentials>,
        GAS_PRICE, GAS_LIMIT,
        <param1>, ..., <paramN>).send();  // constructor params

Alternatively, if you use Truffle, you can make use of its .json output files:

# Inside your Truffle project
$ truffle compile
$ truffle deploy

Then generate the wrapper code using Webuj's Command line tools:

$ cd /path/to/your/Webuj/java/project
$ Webuj truffle generate /path/to/<truffle-smart-contract-output>.json -o /path/to/src/main/java -p com.your.organisation.name

Whether using Truffle or solc directly, either way you get a ready-to-use Java wrapper for your contract.

So, to use an existing contract:

YourSmartContract contract = YourSmartContract.load(
        "0x<address>|<ensName>", <Webuj>, <credentials>, GAS_PRICE, GAS_LIMIT);

To transact with a smart contract:

TransactionReceipt repTransactionReceipt = contract.someMethod(
             <param1>,
             ...).send();

To call a smart contract:

Type result = contract.someMethod(<param1>, ...).send();

For more information refer to Smart Contracts.

Webuj functional-reactive nature makes it really simple to setup observers that notify subscribers of events taking place on the blockchain.

To receive all new blocks as they are added to the blockchain:

Subscription subscription = Webuj.blockObservable(false).subscribe(block -> {
    ...
});

To receive all new transactions as they are added to the blockchain:

Subscription subscription = Webuj.transactionObservable().subscribe(tx -> {
    ...
});

To receive all pending transactions as they are submitted to the network (i.e. before they have been grouped into a block together):

Subscription subscription = Webuj.pendingTransactionObservable().subscribe(tx -> {
    ...
});

Or, if you'd rather replay all blocks to the most current, and be notified of new subsequent blocks being created:

There are a number of other reqTransaction and block replay Observables described in the docs.

Topic filters are also supported:

HucFilter filter = new HucFilter(DefaultBlockParameterName.EARLIEST,
        DefaultBlockParameterName.LATEST, <contract-address>)
             .addSingleTopic(...)|.addOptionalTopics(..., ...)|...;
Webuj.hucLogObservable(filter).subscribe(log -> {
    ...
});

Subscriptions should always be cancelled when no longer required:

subscription.unsubscribe();

Note: filters are not supported on Infura.

For further information refer to Filters and Events and the webujRx interface.

Webuj provides support for both working with HappyUC wallet files (recommended) and HappyUC client admin commands for sending transactions.

Create my wallet

String filePath = Environment.getExternalStorageDirectory().toString() + "/MyWallet";
String fileName = WalletUtils.generateNewWalletFile("123456",new File(filePath),false);
Credentials credentials = WalletUtils.loadCredentials("123456", filePath+"/"+fileName);

To send Huc to another party using your HappyUC wallet file:

Webuj web3 = Webuj.build(new HttpService());  // defaults to http://localhost:8545/
Credentials credentials = WalletUtils.loadCredentials("password", "/path/to/walletfile");
TransactionReceipt repTransactionReceipt = Transfer.sendFunds(
        web3, credentials, "0x<address>|<ensName>",
        BigDecimal.valueOf(1.0), Convert.Unit.HUC)
        .send();

Or if you wish to create your own custom reqTransaction:

Webuj web3 = Webuj.build(new HttpService());  // defaults to http://localhost:8545/
Credentials credentials = WalletUtils.loadCredentials("password", "/path/to/walletfile");

// get the next available nonce
HucGetTransactionCount hucGetRepTransactionCount = Webuj.hucGetRepTransactionCount(
             address, DefaultBlockParameterName.LATEST).sendAsync().get();
BigInteger nonce = hucGetRepTransactionCount.getTransactionCount();

// create our reqTransaction
RawTransaction rawTransaction  = RawTransaction.createHucTransaction(
             nonce, <gas price>, <gas limit>, <toAddress>, <value>);

// sign & send our reqTransaction
byte[] signedMessage = TransactionEncoder.signMessage(rawTransaction, credentials);
String hexValue = Hex.toHexString(signedMessage);
HucSendTransaction hucSendRepTransaction = Webuj.hucSendRawRepTransaction(hexValue).send();
// ...

Although it's far simpler using Webuj's Transfer for transacting with Huc.

Using an HappyUC client's admin commands (make sure you have your wallet in the client's keystore):

Admin Webuj = Admin.build(new HttpService());  // defaults to http://localhost:8545/
PersonalUnlockAccount personalUnlockAccount = Webuj.personalUnlockAccount("0x000...", "a password").sendAsync().get();
if (personalUnlockAccount.accountUnlocked()) {
    // send a reqTransaction
}

If you want to make use of Parity's Personal or Trace, or Ghuc's Personal client APIs, you can use the org.Webuj:parity and org.Webuj:ghuc modules respectively.

A Webuj fat jar is distributed with each release providing command line tools. The command line tools allow you to use some of the functionality of Webuj from the command line:

• Wallet creation
• Wallet password management
• Transfer of funds from one wallet to another
• Generate Solidity smart contract function wrappers

Please refer to the documentation for further information.

In the Java 8 build:

• Webuj provides type safe access to all responses. Optional or null responses are wrapped in Java 8's Optional type.
• Asynchronous requests are wrapped in a Java 8 CompletableFutures. Webuj provides a wrapper around all async requests to ensure that any exceptions during execution will be captured rather then silently discarded. This is due to the lack of support in CompletableFutures for checked exceptions, which are often rethrown as unchecked exception causing problems with detection. See the Async.run() and its associated test for details.

In both the Java 8 and Android builds:

• Quantity payload types are returned as BigIntegers. For simple results, you can obtain the quantity as a String via Response.getResult().
• It's also possible to include the raw JSON payload in responses via the includeRawResponse parameter, present in the HttpService and IpcService classes.

• Ghuc
• Parity

You can run the integration test class CoreIT to verify clients.

For a .NET implementation, check out Nhappyuc.

For a pure Java implementation of the HappyUC client, check out HappyUCJ and HappyUC Harmony.

Please submit a pull request if you wish to include your project on the list:

• ERC-20 RESTful Service
• Huc Wallet by @vikulin
• eth-contract-api by @adridadou
• HappyUC Paper Wallet by @matthiaszimmermann
• Trust HappyUC Wallet
• Presto HappyUC
• Kundera-HappyUC data importer and sync utility by @impetus-opensource

Please submit a pull request if you wish to include your company on the list:

• Amberdata
• blk.io
• comitFS
• ConsenSys
• ING
• Othera
• Pactum
• TrustWallet
• Impetus

Webuj includes integration tests for running against a live HappyUC client. If you do not have a client running, you can exclude their execution as per the below instructions.

To run a full build (excluding integration tests):

$ ./gradlew check

To run the integration tests:

$ ./gradlew  -Pintegration-tests=true :integration-tests:test

• The Nhappyuc project for the inspiration
• Othera for the great things they are building on the platform
• Finhaus guys for putting me onto Nhappyuc
• bitcoinj for the reference Elliptic Curve crypto implementation
• Everyone involved in the HappyUC project and its surrounding ecosystem
• And of course the users of the library, who've provided valuable input & feedback