First example: pongd in crystal.

crystal/.gitignore

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+bin/
+lib/
+shard.lock

crystal/shard.yml

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+name: ipc-examples
+version: 0.6.0 # Will follow the libipc version.
+
+dependencies:
+  ipc:
+    git: ssh://_gitea@git.baguette.netlib.re:2299/Baguette/ipc.cr
+
+targets:
+  pongd:
+    main: src/pongd.cr
+
+authors:
+  - karchnu <karchnu@karchnu.fr>
+
+description: |
+  Examples of libipc usage and its bindings.
+
+license: ISC

crystal/src/colors.cr

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+CRED      = "\033[31m"
+CBLUE     = "\033[36m"
+CGREEN    = "\033[32m"
+CRESET    = "\033[00m"
+CORANGE   = "\033[33m"

crystal/src/pongd.cr

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+require "option_parser"
+require "ipc"
+require "./colors"
+
+verbosity = 1
+service_name = "pong"
+no_response = false
+
+OptionParser.parse do |parser|
+	parser.on "-s service_name", "--service-name service_name", "URI" do |optsn|
+		service_name = optsn
+	end
+
+	parser.on "-n", "--no-response", "Do not provide any response back." do
+		no_response = true
+	end
+
+	parser.on "-v verbosity", "--verbosity verbosity", "Verbosity (0 = nothing is printed, 1 = only events, 2 = events and messages). Default: 1" do |optsn|
+		verbosity = optsn.to_i
+	end
+
+	parser.on "-h", "--help", "Show this help" do
+		puts parser
+		exit 0
+	end
+end
+
+service = IPC::Server.new (service_name)
+
+service.loop do |event|
+	case event
+	when IPC::Event::Timer
+		if verbosity >= 1
+			puts "#{CORANGE}IPC::Event::Timer#{CRESET}"
+		end
+	when IPC::Event::Connection
+		if verbosity >= 1
+			puts "#{CBLUE}IPC::Event::Connection#{CRESET}, client: #{event.fd}"
+		end
+	when IPC::Event::Disconnection
+		if verbosity >= 1
+			puts "#{CBLUE}IPC::Event::Disconnection#{CRESET}, client: #{event.fd}"
+		end
+	when IPC::Event::MessageSent
+		begin
+			if verbosity >= 1
+				puts "#{CGREEN}IPC::Event::MessageSent#{CRESET}, client: #{event.fd}"
+			end
+		rescue e
+			puts "#{CRED}#{e.message}#{CRESET}"
+			service.remove_fd event.fd
+		end
+	when IPC::Event::MessageReceived
+		begin
+			if verbosity >= 1
+				puts "#{CGREEN}IPC::Event::MessageReceived#{CRESET}, client: #{event.fd}"
+				if verbosity >= 2
+					m = String.new event.message.payload
+					puts "#{CBLUE}message type #{event.message.utype}: #{m} #{CRESET}"
+				end
+			end
+			service.send event.message unless no_response
+			if verbosity >= 2 && ! no_response
+				puts "#{CBLUE}sending message...#{CRESET}"
+			end
+
+		rescue e
+			puts "#{CRED}#{e.message}#{CRESET}"
+			service.remove_fd event.fd
+		end
+	else
+		if verbosity >= 1
+			puts "#{CRED}Exception: message #{event} #{CRESET}"
+		end
+	end
+end