This document discusses three Java libraries for working with Cassandra: Cassandra Unit, the Java Driver Object Mapper module, and Achilles. Cassandra Unit allows embedding a Cassandra server for unit testing. The Java Driver Object Mapper provides annotations for object mapping like JPA with a templating system. Achilles is a more full-featured library that started later, providing features like schema validation, dynamic logging, and batch operations. It also has plans for asynchronous APIs and integration with Elasticsearch.

1. Cassandra Java Libraries
DuyHai DOAN, Technical Advocate
@doanduyhai

2. Agenda!
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2
Cassandra Unit
Java Driver Mapping Module
Achilles

3. Cassandra Unit!
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• start an embedded Cassandra server
• useful for unit testing
• mature project, created at August 5th 2011
• designed around Thrift & Hector
• propose a JUnit rule for CQL

4. Cassandra Unit
Demo

5. Java Driver Object Mapper!
@doanduyhai
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• simple mapper
• KISS
• annotations à-la JPA (but no JPA dependencies)
• templating system à-la Spring Data

6. Java Driver Object Mapper!
Mapping
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@Table(keyspace = "mapper_module", name = "users")
public class User {
@PartitionKey
private String login;
private String name;
// getters and setters omitted...
}

7. Java Driver Object Mapper!
Usage
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MappingManager manager = new MappingManager(session);
Mapper mapper = manager.mapper(User.class);
User user = mapper.get("jdoe@fiction.com");
mapper.saveAsync(new User("hsue@fiction.com"));
mapper.delete("jdoe@fiction.com");

8. Java Driver Object Mapper!
Accessors (SpringData template-like) definition
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@Accessor
interface UserAccessor {
@Query("SELECT * FROM users LIMIT :max")
Result<User> firstNUsers(@Param("max") int limit);
}

9. Java Driver Object Mapper!
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Accessors usage
UserAccessor accessor = manager.createAccessor(UserAccessor.class);
List<User> users = accessor.firstNUsers(10).all();
for (User user : users) {
System.out.println( profile.getAddress().getZip() );
}

10. Java Driver Object Mapper
Demo

11. Achilles!
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Why ?
• started in late 2012, when mapper module did not exists
• more involved and more features than the mapper module
• different annotations set (may converge)

12. Achilles
Demo

13. Achilles Architecture!
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Entities Parsing
Schema Validation
Prepare Statements
Custom Configs
Meta Data
Dirty Checking (opt.)
Interceptors
Type Encoding
Dynamic Logging
Object Mapping
Proxy Building (opt.)
Bootstrap
Runtime

14. Main API!
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manager.insert(entity)
manager.update(entity)
manager.remove(entity)
manager.find(Entity.class, primaryKey)

15. Main API!
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Slice query, typed query
RegularStatement select = select().from(“user_messages”)
.where(eq(“user_id”,bindMarker()))
.and(gte(asList(“message_folder”), bindMarker()))
.and(lt(asList(“message_folder”, “date”), bindMarker()))
.limit(10);
List<Message> messages = manager.typedQuery(Message.class, select,
userId, asList(“forums”), asList(“forums”, uuid1))
.get();

16. Main API!
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Native query
RegularStatement nativeQuery = new SimpleStatement(“SELECT * FROM
Message WHERE … LIMIT 1”);
TypedMap firstMessage = manager.nativeQuery(nativeQuery).first();
String interlocutor = firstMessage.getTyped(“interlocutor”);
//Or
String interlocutor = firstMessage.<String>getTyped(“interlocutor”);

17. Main API!
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Counter
Batch mode
Strategies (insert, naming)
Options

18. Documentation!
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Comprehensive Github WIKI
Twitter-clone demo app (demo.achilles.io)
Versioned documentation (HTML & PDF)
JavaDoc

19. RoadMap!
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Asynchronous API (branch Asynchronous)
• main API ( insert(), update(), …)
• slice, typed & native queries
C* 2.1 user defined types (UDT)
Reactive ? (RxJava)
ElasticSearch integration (@olivierbourgain)

20. ! "
!
Q & R

21. Thank You
@doanduyhai
duy_hai.doan@datastax.com
https://academy.datastax.com/