Java 8 and Scala Cassandra client.
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AUTHORS Helenus was the son of King Priam and Queen Hecuba of Troy, and the twin brother of the prophetess Cassandra. Like Cassandra, he was always right, but unlike her, others believed him. Seems like a good name for a layer to access DataStax, Apache, or ScyllaDB's implementations of the Cassandra database. 2017-07-27 15:02:17 -04:00
eclipse-formatting.xml eclipse-formatting 2015-03-16 17:03:17 -07:00
helenus-core.iml Remove Zipkin. Revert abstracted UnitOfWork into single class. 2018-03-28 08:27:49 -04:00
LICENSE Initial commit 2015-02-26 12:42:59 -08:00
NOTES Finish first steps of JCache integration, UnitOfWork statement cache now merges into available JCache at commit. 2018-02-08 10:09:23 -05:00
pom.xml Remove Zipkin. Revert abstracted UnitOfWork into single class. 2018-03-28 08:27:49 -04:00
README.md Remove Scala support and trim Future support at some point I'll re-introduce using Java 8 classes rather than Guava's or Scala's 2017-08-04 11:18:54 -04:00

Helenus

Fast and easy, functional style cutting edge Java 8 Cassandra client for C* 3.x

Features

  • Leverages Java 8 language capabilities to build CQL queries
  • Simple function-style stream API
  • Reactive asynchronous and synchronous API
  • Provides Java mapping for Tables, Tuples, UDTs (User Defined Type), Collections, UDT Collections, Tuple Collections
  • Uses lazy mapping in all cases where possible
  • Supports Java 8 Futures and Guava ListenableFuture

Requirements

  • JVM 8
  • Datastax Driver 3.x
  • Cassandra 3.x
  • Maven

Maven

Latest release dependency:

<dependencies>
	<dependency>
		<groupId>net.helenus</groupId>
		<artifactId>helenus-core</artifactId>
		<version>1.1.0_2.11</version>
	</dependency>
</dependencies>

Simple Example

Model definition:

@Table
public interface Timeline {

	@PartitionKey
	UUID userId();

	@ClusteringColumn
	@Types.Timeuuid
	Date timestamp();

	@Column
	String text();

}

Session initialization:

HelenusSession session = Helenus.init(getSession()).showCql().add(Timeline.class).autoCreateDrop().get();
Timeline timeline = Helenus.dsl(Timeline.class, session.getMetadata());

Select example:

session.select(timeline::userId, timeline::timestamp, timeline::text)
  .where(timeline::userId, eq(userId))
  .orderBy(Query.desc(timeline::timestamp)).limit(5).sync()
  .forEach(System.out::println);

Insert example:

TimelineImpl post = new TimelineImpl();
post.userId=userId;
post.timestamp=new Date(postTime+1000L*i);
post.text="hello";
session.upsert(post).sync();

Model and Repository Example

Account model:

@Table
public interface Account {
	@PartitionKey
	String accountId();
	Date createdAt();
	String organization();
	String team();
	String timezone();
	Map<String, AccountUser> users();
}

AccountUser model:

@UDT
public interface AccountUser {
	String email();
	String firstName();
	String lastName();
}

Abstract repository:

public interface AbstractRepository {
	HelenusSession session();
}

Account repository:


public interface AccountRepository extends AbstractRepository {

	static final Account account = Helenus.dsl(Account.class);
	static final String DEFAULT_TIMEZONE = "America/Los_Angeles";
	default Future<Optional<Account>> findAccount(String accountId) {

		return session()
				.select(Account.class)
				.where(account::accountId, eq(accountId))
				.single()
				.future();
	}

	default Future<Fun.Tuple2<ResultSet, String>> createAccount(
			String email,
			AccountUser user,
			String organization,
			String team,
			String timezone) {

		String accountId = AccountId.next();

		if (timezone == null || timezone.isEmpty()) {
			timezone = DEFAULT_TIMEZONE;
		}

		return session()
			.insert()
			.value(account::accountId, accountId)
			.value(account::createdAt, new Date())
			.value(account::organization, organization)
			.value(account::team, team)
			.value(account::timezone, timezone)
			.value(account::users, ImmutableMap.of(email, user))
			.future(accountId);

	}

	default Future<ResultSet> putAccountUser(String accountId, String email, AccountUser user) {

		return session()
				.update()
				.put(account::users, email.toLowerCase(), user)
				.where(account::accountId, eq(accountId))
				.future();

	}

	default Future<ResultSet> removeAccountUser(String accountId, String email) {

		return session()
				.update()
				.put(account::users, email.toLowerCase(), null)
				.where(account::accountId, eq(accountId))
				.future();

	}

	default Future<ResultSet> dropAccount(String accountId) {

		return session()
				.delete()
				.where(account::accountId, eq(accountId))
				.future();

	}

}