noun
A heavy, dull sound such as that made by thick pieces of metal striking together.
Talking to Postgres via sockets. At this point in time, I'm just experimenting with Clojure; learning core.async.
You need to have a Postgres (13) Database up and running.
docker compose up -dNow you can run the tests with
clj -X:testRequire the following:
(require '[com.clunk.core :as clunk]
'[clojure.core.async :as async]
'[clojure.core.match :as m])
(def username "jimmy")
(def password "banana")
(def database "world")
(def port (int 5432))We can now create a client, and a receive handler that responds to an MD5 Authentication request, and also prints all received messages:
(def client (clunk/socket-client port))
;; Receive Handler
(async/go-loop []
(when-let [msg (async/<! (:in client))]
;; Print any received message
(println (str "Received Message: " msg))
(m/match msg
{:type :AuthenticationMD5}
;; Send MD5 password with received salt
(async/>! (:out client) (clunk/get-password username password (byte-array (:salt msg))))
:else nil)
(recur)))Now we can send the Startup Message:
(async/>!! (:out client) (clunk/get-startup username database))We will see a bunch of received messages:
Received Message: {:type :AuthenticationMD5, :salt [-47 -110 29 -114]}
Received Message: {:type :AuthenticationOk}
Received Message: {:type :ParameterStatus, :status ["application_name" ""]}
Received Message: {:type :ParameterStatus, :status ["client_encoding" "UTF8"]}
Received Message: {:type :ParameterStatus, :status ["DateStyle" "ISO, MDY"]}
Received Message: {:type :ParameterStatus, :status ["integer_datetimes" "on"]}
Received Message: {:type :ParameterStatus, :status ["IntervalStyle" "postgres"]}
Received Message: {:type :ParameterStatus, :status ["is_superuser" "on"]}
Received Message: {:type :ParameterStatus, :status ["server_encoding" "UTF8"]}
Received Message: {:type :ParameterStatus, :status ["server_version" "13.4 (Debian 13.4-1.pgdg100+1)"]}
Received Message: {:type :ParameterStatus, :status ["session_authorization" "jimmy"]}
Received Message: {:type :ParameterStatus, :status ["standard_conforming_strings" "on"]}
Received Message: {:type :ParameterStatus, :status ["TimeZone" "Etc/UTC"]}
Received Message: {:type :BackendKeyData, :id 167, :key 835881833}
Received Message: {:type :ReadyForQuery, :status 73}Finally we can run a query:
(async/>!! (:out client) (clunk/get-query "select 1 as x, 2 as y;"))Which produces the following:
Received Message: {:type :RowDescription, ...}
Received Message: {:type :DataRow, ...}
Received Message: {:type :Close, ...}
Received Message: {:type :ReadyForQuery, ...}And lastly, close the client:
(clunk/close-client client)