jdbc-ring-session

A Clojure library for JDBC backed Ring sessions.

Usage

Use the jdbc-ring-session.core/jdbc-store function to create a new store. The function accepts a clojure.java.jdbc datasource definition:

(ns db.core
  (:require [jdbc-ring-session.core :refer [jdbc-store]]))

(def db
  {:subprotocol "postgresql"
   :subname "session"
   :user "admin"
   :password "admin"})

(def store (jdbc-store db))

database configuration

The session will be stored as a byte array serialized using nippy. The table formats are shown below.

PostgeSQL:

CREATE TABLE session_store
(
  session_id VARCHAR(36) NOT NULL PRIMARY KEY,
  idle_timeout BIGINT,
  absolute_timeout BIGINT,
  value BYTEA
)

Oracle:

CREATE TABLE SESSION_STORE
(
  session_id VARCHAR2(100 BYTE) NOT NULL PRIMARY KEY,
  absolute_timeout NUMBER,
  idle_timeout NUMBER,
  value BLOB
)

MySQL:

CREATE TABLE `session_store` (
  `session_id` VARCHAR(36) NOT NULL,
  `idle_timeout` DOUBLE DEFAULT NULL,
  `absolute_timeout` DOUBLE DEFAULT NULL,
  `value` BLOB,
  PRIMARY KEY (`session_id`)
)

H2:

CREATE TABLE session_store (
  session_id VARCHAR(36) NOT NULL,
  idle_timeout BIGINT DEFAULT NULL,
  absolute_timeout BIGINT DEFAULT NULL,
  value BINARY(10000),
  PRIMARY KEY (session_id)
)

session store initialization

The jdbc-store function accepts an optional map with the keys called :table, :serializer and :deserializer. The :table defaults to :session_store, while the :serializer and :deserializer keys are used to specify how the session data should be serialized and deserialized for the specific database. The library will attempt to figure out the appropriate serializer/deserializer based on the connection type. MySQL, PostgeSQL and Oracle BLOB formats are supported out of the box.

(jdbc-store db {:table :sessions})

custom serialization

The serializer function accepts the session map and returns the serialized value that will be inserted in the table, eg:

(defn serialize-postgres [value]
  (nippy/freeze value))

The deserializer function receives the session value in the database and returns the deserialized session, eg:

(defn deserialize-postgres [value]
  (when value
    (nippy/thaw value)))

stale session cleanup

A cleaner thread is provided in the ring-jdbc-session.cleaner for removing expired sessions from the database. The idle_timeout and absolute_timeout keys are expected to be populated by the ring-session-timeout library. These keys are used by the cleaner to remove stale sessions. The cleaner can be started and stopped as follows:

(ns db.core
  (:require [jdbc-ring-session.cleaner :refer [start-cleaner stop-cleaner]))

(start-cleaner db)

(stop-cleaner session-cleaner)

The start-cleaner function accepts an optional map with the :interval key that defaults to 60. This is the number of seconds to sleep between runs.

(start-cleaner {:interval 120})

Troubleshooting

Running a database on a non standard port

Note that when running a database on a non-standard port, the jdbc datasource definition must be formatted as follows (from jdbc source):

DriverManager (alternative):
    :dbtype      (required) a String, the type of the database (the jdbc subprotocol)
    :dbname      (required) a String, the name of the database
    :host        (optional) a String, the host name/IP of the database
                            (defaults to 127.0.0.1)
    :port        (optional) a Long, the port of the database
                            (defaults to 3306 for mysql, 1433 for mssql/jtds, else nil)
                            (others)     (optional) passed to the driver as properties.

Adding a :port key to the standard DriverManager map will result in the database connection failing with a org.postgresql.util.PSQLException: FATAL: password authentication failed for user, and it can be difficult to trace it back to the DriverManager format.

Using a string subprotocol://user:password@host:post/subname, instead of a DriverManager map will also work.

License

Copyright © 2015 Yogthos

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.