Vangas

This is a Scala driver for Apache Cassandra. It is fully asynchronous and non-blocking based on Akka-IO and Akka-Actors. This driver is not a wrapper on cassandra-java-driver. Currently, Vangas supports only native-protocol-v3.

Features

• Non-blocking IO
• Query
• Query value bindings
• PreparedStatements
• Execute
• Retry of unprepared queries
• ConnectionPool
• LoadBalancing policy
• Pagination using token function
• Most of data-types except Tuples and Custom types

TODOs

• Batch queries
• Authentication
• Value bindings by name
• Compression support
• Listening server-side events
• Add more (to a certain limit) connections when current connections reach their max concurrent request limit.
• Tuples and custom data-types
• Native-protocol-v2 support

Getting started

Create CassandraClient

There should be one CassandraClient per cluster. There is an ActorSystem per CassandraClient.

val client = new CassandraClient(Seq("localhost"))

Session

Sessions are the containers that keep connections to the Cassandra cluster. Each session object serves for one keyspace. There is an actor associated with each session object which handles routing of requests to the connection actors which send them to a cassandra node.

Actor associated with the session has connection pool which holds connection actors' reference. Requests are routed to the connections in round-robin fashion.

Connection

Connection is an actor which keeps the TCP connection to a cassandra node. All CQL commands are sent to the node from this actor. This actor is not exposed to the driver clients.

Create new Session

val session = client.newSession("KEY_SPACE")

WARNING: Don't change the keyspace via USE command in a session. If you need to execute queries on different keyspace, create new session instance.

Don't do this session.execute("USE new_keyspace")

Execute simple query

val results: Future[ResultSet] = session.execute("SELECT * FROM users")
results.onSuccess{ case rs =>
  rs.foreach{ row =>
    row.get[Int](0) //gets the first column which is Int
  }
}

Pimped response

There are syntactic sugars which removes boilerplate codes while processing ResultSets.

import net.vangas.cassandra.pimped._

session.execute("SELECT * FROM users").mapRows { row =>
  //convert to your case class
}

Bind values

val results: Future[ResultSet] = session.execute("SELECT * FROM users WHERE id = ?", 123)

PreparedStatement

val prepare: Future[PreparedStatement] = session.prepare("SELECT * FROM users WHERE id = ?")
val results: Future[ResultSet] = prepare.flatMap{ prepared => session.execute(prepared.bind("123"))}

Close Session

You cannot reuse closed session.

session.close()

Close CassandraClient

You cannot reuse closed CassandraClient.

client.close()

Build

In order to build this project, you need ccm which makes it easy to create and test cassandra cluster locally.

Releases

Vangas is not released yet because it's still under testing. But feel free to evaluate and create pull requests.

License

Copyright (C) 2014 Egemen Kalyoncu

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.