This document provides an overview of the DataStax Java Driver and how to use it to connect to and query Cassandra. It introduces key concepts like CQL, the data model, asynchronous operations, prepared statements, load balancing, and retry policies. The document also includes code examples for connecting to Cassandra, performing basic read and write operations using CQL strings and prepared statements, and more advanced techniques like asynchronous reads, query builders, custom load balancing policies, and object mapping.

1. DataStax Java Driver Unleashed!

2. CQL The new face of Cassandra
* CQL3
* Simpler Data Model using Denormalized Tables
* SQL-like Query Language
* Schema Definition
* CQL Native Protocol
* Introduced in Cassandra 1.2
* Designed for CQL3
* Thrift will keep being supported by Cassandra

3. * Cassandra lives closer to users and application
* Data model expresses your application intent
* Not made for generalizable queries
* Key to a successful project
CQL Data Model Overview

4. CQL3 Data Model
Data duplicated over several tables
CQL3 Query Language
comes with a new Data
Model abstraction
made of denormalized,
statically defined tables

5. CQL3 Data Model
gmason
user_id
1735
tweet_id
phenry
author
Give me liberty or give me death
body
Partition
Key
gmason 1742 gwashington I chopped down the cherry tree
ahamilton 1767 jadams A government of laws, not men
ahamilton 1794 gwashington I chopped down the cherry tree
Clustering
Key
Timeline Table

6. CQL3 Data Model
gmason
user_id
1735
tweet_id
phenry
author
Give me liberty or give me death
body
Partition
Key
gmason 1742 gwashington I chopped down the cherry tree
ahamilton 1767 jadams A government of laws, not men
ahamilton 1794 gwashington I chopped down the cherry tree
Clustering
Key
Timeline Table
CREATE TABLE timeline (
user_id varchar,
tweet_id timeuuid,
author varchar,
body varchar,
PRIMARY KEY (user_id, tweet_id));
CQL

7. DB API
CQL Native Protocol
CQL API OO API
Next Generation Driver
New Driver Architecture

8. * Reference Implementation
* Asynchronous architecture based on Netty
* Prepared Statements Support
* Automatic Fail-over
* Node Discovery
* Cassandra Tracing Support
* Tunable Policies
Java Driver Overview

9. Client
Without
Request Pipelining
Cassandra
Client Cassandra
With
Request Pipelining
Request Pipelining

10. Client
Without
Notifications
With
Notifications
Node
Node
Node
Client
Node
Node
Node
Notifications

11. Client
Thread
Node
Node
Node
Client
Thread
Client
Thread
Node
Driver
Asynchronous Architecture

12. 1
2
3
4
5
6
Client
Thread
Node
Node
Node
Client
Thread
Client
Thread
Node
Driver
Asynchronous Architecture

13. contactPoints = {“10.0.0.1”,”10.0.0.2”}
keyspace = “videodb”
public VideoDbBasicImpl(List<String> contactPoints, String keyspace) {
cluster = Cluster
.builder()
.addContactPoints(
! contactPoints.toArray(new String[contactPoints.size()]))
.build();
session = cluster.connect(keyspace);
}
Creating a Basic Connection

14. public void setUserByUsingString(User user) {
StringBuffer userInsert = new StringBuffer(
"INSERT INTO users (username, firstname, lastname, email, password, created_date) VALUES (");
userInsert.append("'" + user.getUsername() + "'");
userInsert.append("'" + user.getFirstname() + "'");
userInsert.append("'" + user.getLastname() + "'");
userInsert.append("'" + user.getEmail() + "'");
userInsert.append("'" + user.getPassword() + "'");
userInsert.append("'" + user.getCreated_date().toString() + "'");
userInsert.append(")");
session.execute(userInsert.toString());
}
Basic write using insert

15. ! public User getUserByUsernameUsingString(String username) {
! ! User user = new User();
! ! ResultSet rs = session.execute("SELECT * FROM users WHERE username = '"
! ! ! ! + username + "'");
! ! // A result set has Rows which can be iterated over
! ! for (Row row : rs) {
! ! ! user.setUsername(username);
! ! ! user.setFirstname(row.getString("firstname"));
! ! ! user.setLastname(row.getString("lastname"));
! ! ! user.setEmail(row.getString("email"));
! ! ! user.setPassword(row.getString("Password"));
! ! ! user.setCreated_date(row.getDate("created_date"));
! ! }
! ! return user;
! }
Basic Read using Select

16. public void setUserByPreparedStatement(User user) {
BoundStatement bs = setUser.bind();
bs.setString("username", user.getUsername());
bs.setString("firstname", user.getFirstname());
bs.setString("lastname", user.getLastname());
bs.setString("email", user.getEmail());
bs.setString("password", user.getPassword());
bs.setDate("created_date", user.getCreated_date());
! !
session.execute(bs);
}
Writing with Prepared Statements

17. public List<Video> getVideosByUsernameUsingAsyncRead(String username) {
BoundStatement bs = getVideosByUsernamePreparedStatement.bind();
List<ResultSetFuture> futures = new ArrayList<ResultSetFuture>();
List<Video> videos = new ArrayList<Video>();
bs.setString("username", username);
for (Row row : session.execute(bs)) {
futures.add(session.executeAsync(getVideoByIDPreparedStatement
.bind(row.getUUID("videoid"))));
}
for (ResultSetFuture future : futures) {
for (Row row : future.getUninterruptibly()) {
Video video = new Video();
video.setVideoid(row.getUUID("videoid"));
videos.add(video);
}
}
return videos;
}
Asynchronous Read

18. for (String tag : tags) {
BoundStatement bs = getVideosByTagPreparedStatement.bind(tag);
final ResultSetFuture future = session.executeAsync(bs);
future.addListener(new Runnable() {
public void run() {
for (Row row : future.getUninterruptibly()) {
UUID videoId = row.getUUID("videoid");
if (videoIds.putIfAbsent(videoId, PRESENT) == null) {
videoFutures.add(session
.executeAsync(getVideoByIDPreparedStatement
.bind(videoId)));
}
}
}
}, executor);
}
Performing a Read with a Listener

19. public Video getVideoByIdUsingQueryBuilder(String videoId) {
Video video = new Video();
Query query = select().all().from("videodb", "videos")
.where(eq("videoId", videoId)).limit(10);
query.setConsistencyLevel(ConsistencyLevel.ONE);
ResultSet rs = session.execute(query);
for (Row row : rs) {
video.setVideoid(row.getUUID("videoid"));
video.setVideoname(row.getString("videoName"));
video.setUsername(row.getString("username"));
video.setDescription(row.getString("description"));
}
return video;
}
Using the Query Builder

20. Load
Balancing
Policy
Node
Node
Node
Health
Monitor
Load Balancing and Failover
ReconnectionNotifications
Client
Retry
Policy
Response
Dispatcher
1 3
2
4
5
6

21. Node
Node
NodeClient
Datacenter B
Node
Node
Node
Client
Client
Client
Client
Client
Datacenter A
Local nodes are queried
first, if non are available,
the request will be sent
to a remote node.
Multi Datacenter Load Balancing

22. Multi Datacenter Load Balancing
Node
Node
Replica
Node
Client Node
NodeReplica
Replica
Nodes that own a
Replica of the data
being read or written
by the query will be
contacted first.

23. contactPoints = {“10.0.0.1”,”10.0.0.2”}
keyspace = “videodb”
public VideoDbBasicImpl(List<String> contactPoints, String keyspace) {
cluster = Cluster
.builder()
.addContactPoints(
! contactPoints.toArray(new String[contactPoints.size()]))
.withLoadBalancingPolicy(Policies.defaultLoadBalancingPolicy())
.build();
session = cluster.connect(keyspace);
}
Create your own policy!
Add a Load Balancing Policy

24. Client
If the requested
Consistency Level
cannot be reached
(QUORUM here), a
second request with a
lower CL is sent
automatically.
Node
Node Replica
Replica
Node
Replica
Downgrading Retry Policy

25. contactPoints = {“10.0.0.1”,”10.0.0.2”}
keyspace = “videodb”
public VideoDbBasicImpl(List<String> contactPoints, String keyspace) {
cluster = Cluster
.builder()
.addContactPoints(
! contactPoints.toArray(new String[contactPoints.size()]))
.withLoadBalancingPolicy(Policies.defaultLoadBalancingPolicy())
.withRetryPolicy(Policies.defaultRetryPolicy())
.build();
session = cluster.connect(keyspace);
}
Create your own policy!
Specify a Retry Policy

26. public enum Gender {
@EnumValue("m")
MALE,
@EnumValue("f")
FEMALE;
}
@Table(name = "user")
public class User {
@PartitionKey
@Column(name = "user_id")
private String userId;
private String name;
private String email;
private Gender gender;
}
Object Mapping

27. DevCenter an IDE for Developers

28. Questions ?