Run a Jena Server

rainbowfish_jena.clj

(ns rainbowfish.jena
  (:require [clojure.java.io :as io]
            [rainbowfish.config :as config])
  (:import [org.apache.jena.fuseki.main FusekiServer]
           [org.apache.jena.system Txn]
           [org.apache.jena.query DatasetFactory QueryExecutionFactory ResultSetFormatter]
           [org.apache.jena.rdf.model Model ModelFactory]))

(defonce
  ^{:doc "Instance of the Jena server for the lifetime of the program."}
  server (atom nil))

(defn stop []
  (swap!
   server
   (fn [old-server]
     (when old-server (.stop old-server))
     nil)))

(defn restart []
  (swap!
   server
   (fn [old-server]
     (let [options (config/config)]
       (when old-server (.stop old-server))

       (let [ds (DatasetFactory/createTxnMem)
             fuseki (-> (FusekiServer/create)
                        (.add "/ds" ds)
                        (.build))]
         (.start fuseki)

         ;; Just some sample code: print some spos.
         (try
           (Txn/executeRead
            ds
            (fn []
              (let [qx (QueryExecutionFactory/create "SELECT ?s ?p ?o { ?s ?p ?o. }" ds)]
                (ResultSetFormatter/out (.execSelect qx)))))
           (catch Exception e (println e)))

         fuseki)))))