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Speaker: Tim Berglund, Global Director of Training at DataStax So you’re a JVM developer, you understand Cassandra’s architecture, and you’re on your way to knowing its data model well enough to build descriptive data models that perform well. What you need now is to know the Java Driver. What seems like an inconsequential library that proxies your application’s queries to your Cassandra cluster is actually a sophisticated piece of code that solves a lot of problems for you that early Cassandra developers had to code by hand. Come to this session to see features you might be missing and examples of how to use the Java driver in real applications.
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JavaApplica)ons
Building
with Cassandra
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tim name: Tim
role: teacher
kristenname: Kristen
role: marketing
billy role: CEO
matt name: Matt
role: founder
status: active
status: chill
https://github.com/datastax/java-‐driver
DataStax Java Driver
• Open source (ASL 2.0) • Where CQL happens • Ac9vely developed • Now faster than ThriD • Doesn’t make you want to die
Every Use Casehas a Story
YourStory:
apply plugin: 'java'repositories { jcenter()} dependencies { compile 'com.datastax.cassandra:cassandra-driver-core:2.1.2' testCompile 'org.testng:testng:6.8.8' testCompile 'junit:junit:4.11'}
Gradle Build
session.execute( "INSERT INTO sensor \ (sensor_id, reading, time) \ VALUES \ (24601, 2.171828, now())”);
ClusterInterfaceCluster cluster = Cluster.builder() .addContactPoints(“192.168.50.1”) .build(); Session session = cluster.connect(“IoT_keyspace");
YourStory:
ResultSet resultSet = session.execute("SELECT * FROM sensor");
List<Row> rows = resultSet.all();
for(Row row : rows) { String sensorId = row.getString("sensor_id" ); double reading = row.getDouble("reading" ); Date time = row.getDate("time" ); }
BasicQueries
PreparedStatement insertReading = session.prepare( "INSERT INTO sensor \ (sensor_id, reading, time) VALUES (?, ?, ?)” ); Statement statement = insertReading .bind(24601, 2.71828, new Date()) .setConsistencyLevel(ConsistencyLevel.QUORUM);
session.execute(statement);
PreparedStatements
YourStory:
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Cluster cluster = Cluster.builder() .addContactPoints(“192.168.50.1”) .build();
ClusterInterface
Cluster cluster = Cluster.builder() .addContactPoints(“192.168.50.1”, “192.168.50.4”, “192.168.50.8”) .build();
YourStory:
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Outsmar(ng Yourself
• Pick one node • Send all coordina9on traffic to that node • Hey, maybe make it a fat node! • WhiteListPolicy
List<InetSocketAddress> whiteList = new ArrayList<InetSocketAddress>();whiteList.add(...);Cluster c = Cluster.builder().withLoadBalancingPolicy( new WhiteListPolicy( new RoundRobinPolicy(), whiteList)).build();
WhiteListing
YourStory:
apply plugin: 'java'repositories { jcenter()} dependencies { compile 'com.datastax.cassandra:cassandra-driver-core:2.1.2' compile 'com.datastax.cassandra:cassandra-driver-mapping:2.1.2' testCompile 'org.testng:testng:6.8.8' testCompile 'junit:junit:4.11'}
MapperObject
CREATE TABLE sensor ( sensor_id int, reading double, time timestamp );
MapperObject
@UDT(keyspace = "IoT_keyspace", name = "sensor") public class Sensor { private int sensorId; private double reading; private Date Time; // getters and setters elided with extreme prejudice...}
MapperObject
MappingManager manager = new MappingManager(session);Mapper mapper = manager.mapper(Sensor.class);Sensor reading = mapper.get("24601");
YourStory:
ResultSetFuture future = session.executeAsync("SELECT * FROM sensor");
// Returns immediately// Go do productive things here…// Then finally block on the results when you must
ResultSet futureResults = future.get();List<Row> rows = resultSet.all();
FutureResults
Executor executor = Executors.newCachedThreadPool();ResultSetFuture future = session.executeAsync("SELECT * FROM sensor");
future.addListener(new Runnable() { public void run() { // Do the things here… } }, executor);
FutureResults
YourStory:
ThankYou!
