Add a simple example.

crystal/makefile.user

@@ -1,8 +1,12 @@
-WS_SERVICE  ?= 127.0.0.1:8080
+WS_PORT     ?= 8080
+WS_SERVICE  ?= 127.0.0.1:$(WS_PORT)
+
+WS_TARGET_SERVICE ?= pong
+WS_TARGET         ?= unix:/tmp/.libipc-run/$(WS_TARGET_SERVICE)
 init-websocket-tcpd:
 	@# '-b' binary, '-E' quit on end-of-file, 'ws-l' websocket URI to listen
 	@# each connection is redirected to last parameter
-	websocat -b -E ws-l:$(WS_SERVICE) unix:/tmp/.libipc-run/pong
+	websocat -b -E ws-l:$(WS_SERVICE) $(WS_TARGET)
 
 init-websocket-client:
 	@# websocat -b -E tcp-l:127.0.0.1:9000 ws://127.0.0.1:9999

crystal/src/tcp-unix-to-ipc-unix.cr

@@ -0,0 +1,51 @@
+# WARNING: This code is for DEBUG only.
+
+# Listen to a UNIX socket, connect to another one.
+require "ipc"
+
+ipc = IPC.new
+ipc.timer 5000 # timer event every 5 seconds
+fd = ipc.connect "pong" # 'pong' service
+
+ipc.loop do |event|
+  case event.type
+  when LibIPC::EventType::MessageRx
+    m = event.message
+    if m.nil?
+      puts "No message"
+    else
+      received = String.new(m.to_unsafe, m.size)
+      pp! received
+      ipc.schedule event.fd, m, m.size
+    end
+  when LibIPC::EventType::MessageTx
+    puts "A message has been sent"
+  when LibIPC::EventType::Connection
+    puts "A client just connected #JOY"
+  when LibIPC::EventType::Disconnection
+    puts "A client just disconnected #SAD"
+  when LibIPC::EventType::Timer
+    STDOUT.write "\rTimer!".to_slice
+  when LibIPC::EventType::External
+  else
+    puts "Unexpected: #{event.type}"
+    exit 1
+  end
+end
+
+# Read an IPC network packet and remove the first 4 bytes.
+buffer = Bytes.new 1_000_000
+while true
+	len = STDIN.read buffer
+	break if len == 0
+	STDOUT.write buffer[4.. len -1]
+end
+
+# Input to IPC network packets.
+buffer = Bytes.new 1_000_000
+while true
+	len = STDIN.read buffer
+	break if len == 0
+	STDOUT.write_bytes len, IO::ByteFormat::BigEndian
+	STDOUT.write buffer[0.. len -1]
+end