XChange-stream is a Java library providing a simple and consistent streaming API for interacting with Bitcoin and other crypto currency exchanges via WebSocket protocol.

It is build on top of the XChange library providing new interfaces for the exchanges' streaming APIs. Users can subscribe for live updates via reactive streams of RxJava library.

• Easy to use - no need to hack WebSocket and other backends.
• Consistent & simple API across all implemented exchanges.
• Extends well-known & active Java library XChange.
• Reactive streams are fun to work with.
• Modular extensibility.

Xchange-stream is on Maven Central. You will need xchange-stream-core dependency and xchange-XYZ where XYZ is supported exchange (eg. xchange-bitstamp). Add the following into your pom.xml.

<dependency>
    <groupId>info.bitrich.xchange-stream</groupId>
    <artifactId>xchange-stream-core</artifactId>
    <version>x.y.z</version>
</dependency>

<dependency>
    <groupId>info.bitrich.xchange-stream</groupId>
    <artifactId>xchange-XYZ</artifactId>
    <version>x.y.z</version>
</dependency>

For snapshots version (built from develop branch), add the following repository to your pom.xml file.

<repository>
  <id>sonatype-oss-snapshot</id>
  <snapshots/>
  <url>https://oss.sonatype.org/content/repositories/snapshots</url>
</repository>

XChange-stream follows major and minor version from XChange library. So version 4.2.x is based on latest 4.2. release of XChange.

Use the same library as XChange but instead of ExchangeFactory use StreamingExchangeFactory that creates StreamingExchange instead of Exchange. Then you can call getStreamingMarketDataService to subscribe to trade data.

StreamingExchange exchange = StreamingExchangeFactory.INSTANCE.createExchange(BitstampStreamingExchange.class.getName());

// Connect to the Exchange WebSocket API. Blocking wait for the connection.
exchange.connect().blockingAwait();

// Subscribe to live trades update.
exchange.getStreamingMarketDataService()
        .getTrades(CurrencyPair.BTC_USD)
        .subscribe(trade -> {
            LOG.info("Incoming trade: {}", trade);
        }, throwable -> {
            LOG.error("Error in subscribing trades.", throwable);
        });

// Subscribe order book data with the reference to the subscription.
Disposable subscription = exchange.getStreamingMarketDataService()
                                  .getOrderBook(CurrencyPair.BTC_USD)
                                  .subscribe(orderBook -> {
                                       // Do something
                                  });

// Unsubscribe from data order book.
subscription.dispose();

// Disconnect from exchange (non-blocking)
exchange.disconnect().subscribe(() -> LOG.info("Disconnected from the Exchange"));

More information about reactive streams can be found at RxJava wiki.

Listening for live updates of

• ✔️ - implemented
• 🚧 - missing but can be implemented
• ❌ - not supported by the exchange

GDAX authenticated live updates are not yet supported, hopefully it will be added in the near future.

If you missing a specific exchange implementation, feel free to propose a pull request or open an issue with some sweet BTC bounty.

Copyright 2017 Zdenek Dolezal, Michal Oprendek

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.