shaded_jar

Using the shaded JAR

The default driver JAR depends on Netty, which is used internally for networking.

This explicit dependency can be a problem if your application already uses another Netty version. To avoid conflicts, we provide a "shaded" version of the JAR, which bundles the Netty classes under a different package name:

<dependency>
  <groupId>com.datastax.cassandra</groupId>
  <artifactId>cassandra-driver-core</artifactId>
  <version>3.4.0</version>
  <classifier>shaded</classifier>
  <!-- Because the shaded JAR uses the original POM, you still need
       to exclude this dependency explicitly: -->
  <exclusions>
    <exclusion>
      <groupId>io.netty</groupId>
      <artifactId>*</artifactId>
    </exclusion>
  </exclusions>
</dependency>

If you also use the mapper, you need to remove its dependency to the non-shaded JAR:

<dependency>
  <groupId>com.datastax.cassandra</groupId>
  <artifactId>cassandra-driver-core</artifactId>
  <version>3.4.0</version>
  <classifier>shaded</classifier>
  <exclusions>
    <exclusion>
      <groupId>io.netty</groupId>
      <artifactId>*</artifactId>
    </exclusion>
  </exclusions>
</dependency>
<dependency>
  <groupId>com.datastax.cassandra</groupId>
  <artifactId>cassandra-driver-mapping</artifactId>
  <version>3.4.0</version>
  <exclusions>
    <exclusion>
      <groupId>com.datastax.cassandra</groupId>
      <artifactId>cassandra-driver-core</artifactId>
    </exclusion>
  </exclusions>
</dependency>

Limitations

When using the shaded jar, it is not possible to configure the Netty layer.

Extending NettyOptions is not an option because NettyOptions API exposes Netty classes, and as such it should only be extended by clients using the non-shaded version of driver. Attempting to extend NettyOptions with shaded Netty classes is not supported, and in particular for OSGi applications, it is likely that such a configuration would lead to compile and/or runtime errors.

Also, with shaded Netty classes, it is not possible to benefit from Netty native transports.

It is therefore normal to see the following log line when the driver starts and detects that shaded Netty classes are being used:

Detected shaded Netty classes in the classpath; native epoll transport will not work properly, defaulting to NIO.