Speaker(s): 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.

1. JavaApplica)ons
Building
with
Cassandra

2. Treat Cassandra
Like a Database

3. An Awesome
Database
• Always
on
• Horizontally
scalable
• Mul5ple
data
centers
• Cloud/hybrid
• Web/mobile/IoT

4. 2000
4000
6000
8000
A000
C000
E000
0000
Client Machine
Load Balancer

5. tim
name:
Tim
role:
teacher
kristen
name:
Kristen
role:
marketing
billy
role:
CEO
matt
name:
Matt
role:
founder
status:
active
status:
chill

6. CREATE TABLE product_browsing_data
(product_id uuid,
user_id uuid,
clicked_at timestamp,
serialized_browsing_data text,
PRIMARY KEY (product_id, user_id, clicked_at)
);

7. https://github.com/datastax/java-­‐driver

8. DataStax
Java
Driver
• Open
source
(ASL
2.0)
• Where
CQL
happens
• Ac5vely
developed
• Now
faster
than
ThriK
• Doesn’t
make
you
want
to
die

9. Every Use Case
has a Story

10. Your
Story:

11. 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

12. session.execute(
"INSERT INTO sensor
(sensor_id, reading, time)
VALUES
(24601, 2.171828, now())”);
Cluster
Interface
Cluster cluster = Cluster.builder()
.addContactPoints(“192.168.50.1”)
.build();
Session session = cluster.connect(“IoT_keyspace");

13. Your
Story:

14. 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" );
}
Basic
Queries

15. 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);
Prepared
Statements

16. Your
Story:

17. 2000
4000
6000
8000
A000
C000
E000
0000
Client Machine

18. Cluster
Interface
Cluster cluster = Cluster.builder()
.addContactPoints(“192.168.50.1”)
.build();

19. Cluster
Interface
Cluster cluster = Cluster.builder()
.addContactPoints(“192.168.50.1”,
“192.168.50.4”,
“192.168.50.8”)
.build();

20. Your
Story:

21. 2000
4000
6000
8000
A000
C000
E000
0000
Client Machine

22. 2000
4000
6000
8000
A000
C000
E000
0000
Client Machine
1.2ms
2.9ms
15.3ms

23. Outsmar)ng
Yourself
• Pick
one
node
• Send
all
coordina5on
traffic
to
that
node
• Hey,
maybe
make
it
a
fat
node!
• WhiteListPolicy
• PLEASE
DO
NOT
DO
THIS

24. List<InetSocketAddress> whiteList = new
ArrayList<InetSocketAddress>();
whiteList.add(...);
Cluster c = Cluster.builder().withLoadBalancingPolicy(
new WhiteListPolicy(
new RoundRobinPolicy(),
whiteList)).build();
White
Listing

25. Your
Story:

26. 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

27. 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...
}

28. MapperObject
MappingManager manager = new MappingManager(session);
Mapper mapper = manager.mapper(Sensor.class);
Sensor reading = mapper.get("24601");

29. Your
Story:

30. 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();
Future
Results

31. Executor executor = Executors.newCachedThreadPool();
ResultSetFuture future =
session.executeAsync("SELECT * FROM sensor");
future.addListener(new Runnable() {
public void run() {
// Do the things here…
}
}, executor);
Future
Results

32. Your
Story:

34. Thank
You!