#203 - Revise Cassandra Examples.

Simplify examples by adopting Spring Boot 1.4 improvements. Upgrade Cassandra Java driver to 3.0.3. Add examples for Ingalls (Query derivation, projection, Java 8 feature support).

Cassandra example setup is now self-contained by requiring just a running Cassandra instance.
Keyspace and tables are created during the tests. Examples also check if Cassandra is running and some examples additionally check the required version. Test execution is skipped if conditions are not met.

Cassandra (2.x) is started with TravisCI.

cassandra/util/src/main/java/example/springdata/cassandra/util/CassandraVersion.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2016 the original author or authors.
+ *
+ * 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.
+ */
+package example.springdata.cassandra.util;
+
+import org.springframework.data.util.Version;
+import org.springframework.util.Assert;
+
+import com.datastax.driver.core.ResultSet;
+import com.datastax.driver.core.Row;
+import com.datastax.driver.core.Session;
+
+import lombok.experimental.UtilityClass;
+
+/**
+ * Utility to retrieve the Cassandra release version.
+ *
+ * @author Mark Paluch
+ */
+@UtilityClass
+public class CassandraVersion {
+
+	/**
+	 * Retrieve the Cassandra release version.
+	 *
+	 * @param session must not be {@literal null}.
+	 * @return the release {@link Version}.
+	 */
+	public static Version getReleaseVersion(Session session) {
+
+		Assert.notNull(session, "Session must not be null");
+
+		ResultSet resultSet = session.execute("SELECT release_version FROM system.local;");
+		Row row = resultSet.one();
+
+		return Version.parse(row.getString(0));
+	}
+}

cassandra/util/src/main/java/example/springdata/cassandra/util/RequiresCassandraKeyspace.java

@@ -0,0 +1,124 @@
+/*
+ * Copyright 2016 the original author or authors.
+ *
+ * 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.
+ */
+package example.springdata.cassandra.util;
+
+import java.net.InetSocketAddress;
+import java.net.Socket;
+import java.util.concurrent.TimeUnit;
+
+import org.junit.AssumptionViolatedException;
+import org.junit.rules.ExternalResource;
+import org.springframework.data.util.Version;
+import org.springframework.util.Assert;
+
+import com.datastax.driver.core.Cluster;
+import com.datastax.driver.core.NettyOptions;
+import com.datastax.driver.core.Session;
+
+import io.netty.channel.EventLoopGroup;
+
+/**
+ * Implementation of an {@link ExternalResource} to verify Apache Cassandra is running and listening on the given
+ * contact point. This rule also creates a keyspace if it not exists.
+ *
+ * @author Mark Paluch
+ */
+public class RequiresCassandraKeyspace extends ExternalResource {
+
+	private final int timeout = 30;
+	private final String host;
+	private final int port;
+	private final String keyspaceName;
+	private Version requiresVersion;
+
+	private RequiresCassandraKeyspace(String host, int port, String keyspaceName) {
+
+		this.host = host;
+		this.port = port;
+		this.keyspaceName = keyspaceName;
+	}
+
+	/**
+	 * Require a running Cassandra instance on {@code localhost:9042}.
+	 *
+	 * @return the {@link RequiresCassandraKeyspace} rule
+	 */
+	public static RequiresCassandraKeyspace onLocalhost() {
+		return new RequiresCassandraKeyspace("localhost", 9042, "example");
+	}
+
+	/**
+	 * Setup a version requirement.
+	 *
+	 * @param version must not be {@literal null}.
+	 * @return the {@link RequiresCassandraKeyspace} rule
+	 */
+	public RequiresCassandraKeyspace atLeast(Version version) {
+
+		Assert.notNull(version, "Required version must not be null!");
+
+		this.requiresVersion = version;
+		return this;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.junit.rules.ExternalResource#before()
+	 */
+	@Override
+	protected void before() throws Throwable {
+
+		try (Socket socket = new Socket()) {
+			socket.setTcpNoDelay(true);
+			socket.setSoLinger(true, 0);
+			socket.connect(new InetSocketAddress(host, port), timeout);
+
+		} catch (Exception e) {
+			throw new AssumptionViolatedException(String.format("Seems as Cassandra is not running at %s:%s.", host, port),
+					e);
+		}
+
+		Cluster cluster = Cluster.builder().addContactPoint(host).withPort(port).withNettyOptions(new NettyOptions() {
+			@Override
+			public void onClusterClose(EventLoopGroup eventLoopGroup) {
+				eventLoopGroup.shutdownGracefully(0, 0, TimeUnit.MILLISECONDS).syncUninterruptibly();
+			}
+		}).build();
+
+		Session session = cluster.newSession();
+
+		try {
+
+			if (requiresVersion != null) {
+
+				Version cassandraReleaseVersion = CassandraVersion.getReleaseVersion(session);
+
+				if (cassandraReleaseVersion.isLessThan(requiresVersion)) {
+					throw new AssumptionViolatedException(
+							String.format("Cassandra at %s:%s runs in Version %s but we require at least %s", host, port,
+									cassandraReleaseVersion, requiresVersion));
+				}
+			}
+
+			session.execute(String.format("CREATE KEYSPACE IF NOT EXISTS %s \n"
+					+ "WITH REPLICATION = { 'class' : 'SimpleStrategy', 'replication_factor' : 1 };", keyspaceName));
+		} finally {
+			session.close();
+			cluster.close();
+		}
+	}
+
+}