Socket programming in Clojure

Question

I'm a Clojure noob, so bear with me. I'm trying to write a simple program to send a command through a socket and get a response. My code is:

(def IPaddress "10.71.18.81")
(def port 1500)

(def socket (new Socket IPaddress port))
(print (clojure.string/join ["\nConnected to HSM: " (. socket isConnected)]))
(def in (DataInputStream. (BufferedInputStream. (. socket getInputStream))))
(def out (DataOutputStream. (BufferedOutputStream. (. socket getOutputStream))))
(def command "Some string")
(. out WriteUTF command)
(def response (. in readUTF))
(print (clojure.string/join ["Output from HSM: " response]))

The error is "Exception in thread "main" java.lang.IllegalArgumentException: No matching method: writeUTF". I'm having trouble understanding Java interop, and accessing object methods, etc. Thanks in advance.

EDIT: If anyone is interested, my final working code is included here:

(def IPaddress "10.71.18.81")
(def port 1500)

(def socket (Socket. IPaddress port))
(println "Connected:" (.isConnected socket))
(def in (DataInputStream. (BufferedInputStream. (.getInputStream socket))))
(def out (DataOutputStream. (BufferedOutputStream. (.getOutputStream socket))))
(def command "Some string")
(println "Input:" command)
(.writeUTF out command)
(.flush out)
(def response (.readUTF in))
(println "Output: " response)

I have edited it to make it more idiomatic Clojure

DanLebrero
– DanLebrero

2014-08-13 16:32:50 +00:00
Commented Aug 13, 2014 at 16:32 — DanLebrero
– DanLebrero, Commented Aug 13, 2014 at 16:32

Adam DeWitt · Accepted Answer · 2018-11-21 14:38:49Z

4

I realize this is pretty old but it is one of the only examples I have found for reading and writing to a socket with clojure. I needed to experiment a bit to get your code working so it might be useful to someone to the results of that effort:

(import (java.net Socket))
(import (java.io DataInputStream DataOutputStream))

(def IPaddress "127.0.0.1")
(def port 1500)
(def command "Some string\n")
(def socket (Socket. IPaddress port))

(def in (DataInputStream. (.getInputStream socket)))
(def out (DataOutputStream. (.getOutputStream socket)))

(println "Input:" command)
(.writeUTF out command)

(def response (.readLine in))
(println "Output: " response)

answered Nov 21, 2018 at 14:38

Adam DeWitt

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DanLebrero · Accepted Answer · 2014-08-13 11:35:43Z

2

Java is case sensite so it should be (. out writeUTF command). Note that the prefer syntax for interop is (.writeUTF out command) which is equivalent to your statement

answered Aug 13, 2014 at 11:35

DanLebrero

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1 Comment

Conor Leonard Over a year ago

Thank you very much. There were a few other small errors which have been fixed.

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