Cassaforte is a Clojure client for Apache Cassandra and DataStax Enterprise. It is built around CQL 3 and focuses on ease of use. You will likely find that using Cassandra from Clojure has never been so easy.

2.0.0 is a major release that introduces breaking API changes, new features and compatibility with Cassandra 2.1.

Changes between 1.3.x and 2.0.0

Cassaforte 2.0 has breaking API changes in most namespaces.

Client (Session) is Explicit Argument

All Cassaforte public API functions that issue requests to Cassandra now require a client (session) to be passed as an explicit argument:

  (:require [clojurewerkz.cassaforte.client :as cc]
            [clojurewerkz.cassaforte.cql    :as cql]))

(let [conn (cc/connect [""])]
  (cql/use-keyspace conn "cassaforte_keyspace"))
  (:require [clojurewerkz.cassaforte.client :as cc]
            [clojurewerkz.cassaforte.cql    :as cql]
            [clojurewerkz.cassaforte.query :refer :all]))

(let [conn (cc/connect [""])]
  (cql/create-table conn "user_posts"
                (column-definitions {:username :varchar
                                     :post_id  :varchar
                                     :body     :text
                                     :primary-key [:username :post_id]})))
  (:require [clojurewerkz.cassaforte.client :as cc]
            [clojurewerkz.cassaforte.cql    :as cql]))

(let [conn (cc/connect [""])]
  (cql/insert conn "users" {:name "Alex" :age (int 19)}))

Hayt 2.0

Hayt dependency has been upgraded to 2.0 (GA).

Query DSL Taken From Hayt 2.0

Cassaforte no longer tries to support query condition DSLs for both Hayt 1.x and Hayt 2.0. Hayt 2.0 is the only supported flavour now and is the future.

Some examples of the changes:

;; before
(where :name "Alex")

;; after
(where [[= :name "Alex"]])
(where {:name "Alex"})

;; before
(where :name "Alex" :city "Munich")

;; after
(where [[= :name "Alex"]
        [= :city "Munich"]])
(where {:name "Alex" :city "Munich"})

;; before
(where :name "Alex" :age [> 25])

;; after
(where [[= :name "Alex"]
        [> :age  25]])

;; before
(where :name "Alex" :city [:in ["Munich" "Frankfurt"]])

;; after
(where [[= :name "Alex"]
        [:in :city ["Munich" "Frankfurt"]]])

As it’s easy to see, the new condition style closer resembles Clojure itself and thus was a reasonable decision on behalf of Hayt developers.

Policy Namespace

Policy-related functions from clojurewerkz.cassaforte.client were extracted into clojurewerkz.cassaforte.policies:

(require '[clojurewerkz.cassaforte.policies :as cp])

(cp/exponential-reconnection-policy 100 1000)
(require '[clojurewerkz.cassaforte.policies :as cp])

(let [p (cp/round-robin-policy)]
  (cp/token-aware-policy p))

DataStax Java Driver Update

DataStax Java driver has been updated to 2.1.x.

Cassandra 2.1 Compatibility

Cassaforte 2.0 is compatible with Cassandra 2.1.

Cassandra Sessions Compatible with with-open

Session#shutdown was renamed to Session#close in cassandra-driver-core. Cassaforte needs to be adapted to that.

Contributed by Jarkko Mönkkönen.

TLS and Kerberos Support

Cassaforte now supports TLS connections and Kerberos authentication via DataStax CQL extensions.

The :ssl connection option now can be a map with two keys:

  • :keystore-path
  • :keystore-password

which provide a path and password to a JDK KeyStore on disk, created with keytool.

Optionally, an instance of SSLOptions can be provided via the :ssl-options connection option.

Contributed by Max Barnash.

GH issue: #60.

Support for overriding default SSL cipher suites

Providing a :cipher-suites key in the :ssl connection option allows to specify cipher suites that are enabled when connecting to a cluster with SSL. The value of this key is a Seq of Strings (e.g. a vector) where each item specifies a cipher suite:

  (:require [clojurewerkz.cassaforte.client :as cc]))

(cc/build-cluster {:ssl {:keystore-path "path/to/keystore"
                         :keystore-password "password"}})]
                         :cipher-suites ["TLS_RSA_WITH_AES_128_CBC_SHA"]}}

The :cipher-suites key is optional and may be omitted, in which case Datastax Java driver’s default cipher suites (com.datastax.driver.core.SSLOptions/DEFAULT_SSL_CIPHER_SUITES) are enabled.

This can be used to work around the need to install Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files required by the default set of cipher suites. TLS_RSA_WITH_AES_128_CBC_SHA is a suite in the default set that works with the standard JCE. E.g. by specifying just that one, as in the code example, the standard JCE is enough.

Contributed by Juhani Hietikko.

GH issue: #61.

Cassandra Native Protocol v2 as Default

To preserve Cassandra 2.0 compatibility yet continue using the most recent Cassandra Java driver Cassaforte now uses native protocol v2 by default. v3 can be opted into using the :protocol-version connection option (with value of 3).

Double Licensed Under APL 2.0 and EPL 1.0

The project is now double-licensed under the Eclipse Public License 1.0 and Apache Public License 2.0. The codebase now includes APL 2.0 headers. License files for both APL 2.0 and EPL 1.0 are included in the distribution.

Fetch Size Support

(Internal to the client) automatic paging of result set rows now can be configured or disabled altogether, e.g. when running into problems similar to CASSANDRA-6722.

clojurewerkz.cassaforte.client/with-fetch-size is a macro that does that:

(require '[clojurewerkz.cassaforte.client :as cc])

;; alter page size
(cc/with-fetch-size 8192
  (comment "SELECT queries go here"))

;; disable internal client paging
(cc/with-fetch-size Integer/MAX_VALUE
  (comment "SELECT queries go here"))

Default fetch size is unaltered (Cassaforte relies on the Java driver default). This setting only makes sense for a certain subset of SELECT queries.

Clojure 1.4 and 1.5 Support Dropped

Cassaforte now requires Clojure 1.6.0.

Collections Converted to Clojure Data Structures

Cassandra maps, sets and lists are now automatically converted to their immutable Clojure counterparts.

Atomic Batches Support

Atomic batches are now easier to use with Cassaforte:

(require '[clojurewerkz.cassaforte.client :as client])
(require '[clojurewerkz.cassaforte.cql :as cql :refer :all])
(require '[clojurewerkz.cassaforte.query :refer :all])
(require '[qbits.hayt.dsl.statement :as hs])

(let [s (client/connect [""])]
  (cql/atomic-batch s (queries
                         (hs/insert :users (values {:name "Alex" :city "Munich" :age (int 19)}))
                         (hs/insert :users (values {:name "Fritz" :city "Hamburg" :age (int 28)})))))

clojurewerkz.cassandra.cql/iterate-table Now Terminates

clojurewerkz.cassandra.cql/iterate-table no longer produces an infinite sequence.

Keyspace as Option

It is now possible to choose keyspace via an option:

  (:require [clojurewerkz.cassaforte.client :as cc]))

(let [conn (cc/connect {:hosts [""] :keyspace "a-keyspace"})]

Contributed by Max Barnash (DataStax).

URI Connections

It is now possible to connect to a node and switch to a namespace using a URI string:

  (:require [clojurewerkz.cassaforte.client :as cc]))

;; connects to node and uses "new_cql_keyspace" as keyspace
(cc/connect-with-uri "cql://")

Compression Option

:compression is a new option that can be used when connecting:

(require '[clojurewerkz.cassaforte.client :as client])

(let [s (client/connect [""] "my-keyspace" {:compression :snappy})]

Valid compression values are:

  • :snappy
  • :lz4
  • :none (or nil)

Contirbuted by Max Barnash (DataStax).

Fixes Race Condition in Async Operations

Async database operations no longer suffer from a race condition between issueing them and definiting callbacks on the returned future value.

Contributed by Kirill Chernyshov.

Correct Deserialisation of Empty Strings

Empty string values are now correctly deserialised (previously they were returned as nil).

GH issue: #91.

Prepared Statement Cache Removed

Prepared statement cache was affecting client correctness in some cases and was removed.

Clojure 1.7.0-alpha2+ Compatibility

Cassaforte is now compatible with Clojure 1.7.0-alpha2 and later versions.

News and Updates

New releases and updates are announced on Twitter. Cassaforte also has a mailing list, feel free to ask questions and report issues there.

Cassaforte is a ClojureWerkz Project

Cassaforte is part of the group of libraries known as ClojureWerkz, together with

  • Langohr, a Clojure client for RabbitMQ that embraces the AMQP 0.9.1 model
  • Monger, a Clojure MongoDB client for a more civilized age
  • Elastisch, a minimalistic Clojure client for ElasticSearch
  • EEP, a Clojure library for stream (event) processing
  • Neocons, a Clojure client for the Neo4J REST API
  • Quartzite, a powerful scheduling library

and several others. If you like Cassaforte, you may also like our other projects.

Let us know what you think on Twitter or on the Clojure mailing list.

About the Author

Michael on behalf of the ClojureWerkz Team.