diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..724bbe1
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+compiled/
diff --git a/rmq/client.rkt b/rmq/client.rkt
new file mode 100644
index 0000000..c09b8ee
--- /dev/null
+++ b/rmq/client.rkt
@@ -0,0 +1,16 @@
+#lang racket/base
+
+(provide )
+
+(require "private/util.rkt")
+
+(module+ test (require rackunit))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(struct client (callback-url-base
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define (subscribe! client topic [callback #f]
+
diff --git a/rmq/private/util.rkt b/rmq/private/util.rkt
new file mode 100644
index 0000000..9d1b2f7
--- /dev/null
+++ b/rmq/private/util.rkt
@@ -0,0 +1,31 @@
+#lang racket/base
+
+(provide random-hex-string
+         extend-url-string-query)
+
+(require (only-in file/sha1 bytes->hex-string))
+(require (only-in racket/random crypto-random-bytes))
+(require net/url)
+
+(module+ test (require rackunit))
+
+(define (random-hex-string half-length)
+  (bytes->hex-string (crypto-random-bytes half-length)))
+
+(define (extend-url-string-query urlstr extension)
+  (define u (string->url urlstr))
+  (url->string (struct-copy url u [query (append (url-query u) extension)])))
+
+(module+ test
+  (check-equal? (extend-url-string-query "http://localhost/" '((a . "hi")))
+                "http://localhost/?a=hi")
+  (check-equal? (extend-url-string-query "http://localhost/" '())
+                "http://localhost/")
+  (check-equal? (extend-url-string-query "http://localhost?foo=bar" '())
+                "http://localhost?foo=bar")
+  (check-equal? (extend-url-string-query "http://localhost/?foo=bar" '())
+                "http://localhost/?foo=bar")
+  (check-equal? (extend-url-string-query "http://localhost?foo=bar" '((a . "hi")))
+                "http://localhost?foo=bar&a=hi")
+  (check-equal? (extend-url-string-query "http://localhost/?foo=bar" '((a . "hi")))
+                "http://localhost/?foo=bar&a=hi"))
diff --git a/rmq/main.rkt b/rmq/server.rkt
similarity index 98%
rename from rmq/main.rkt
rename to rmq/server.rkt
index d4276b8..13b9072 100644
--- a/rmq/main.rkt
+++ b/rmq/server.rkt
@@ -1,16 +1,18 @@
 #lang syndicate/actor
 
+(provide )
+
 (require racket/format)
 (require racket/set)
-(require racket/random)
 (require net/url)
 (require net/uri-codec)
-(require file/sha1)
 
 (require/activate syndicate/drivers/timer)
 (require/activate syndicate/drivers/web)
 (require syndicate/protocol/advertise)
 
+(require "private/util.rkt")
+
 (module+ test (require rackunit))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -181,7 +183,7 @@
 (define (subscription-change-validate mode lease topic callback)
   (define u (string->url callback))
   (define res (url->resource u))
-  (define challenge (bytes->hex-string (crypto-random-bytes 16)))
+  (define challenge (random-hex-string 16))
   (define id (gensym 'validation))
   (define extra-query (list* (cons 'hub.mode mode)
                              (cons 'hub.topic topic)