--- a/bash-completion.sh	Sun Aug 07 10:45:05 2022 +0200
+++ b/bash-completion.sh	Sun Aug 21 00:16:50 2022 +0200
@@ -22,27 +22,54 @@
 	w2=${COMP_WORDS[COMP_CWORD-2]}
 	w3=${COMP_WORDS[COMP_CWORD-3]}
 
-	DATA_TYPE=(
-		"string"
-		"integer"
-		"boolean"
+	CONNECTION_STRINGS=(
+		"udp://127.0.0.1:64000"
+		"tcp://127.0.0.1:64000"
+		"sctp://127.0.0.1:64000"
+		"uds:///tmp/relpipe.socket"
 	)
 
-	BOOLEAN_VALUES=(
-		"true"
-		"false"
+	OPTIONS=(
+		"protocol"
+		"role"
+		"mode"
+		"host"
+		"port"
+		"path"
+		"delay"
+	)
+
+	PROTOCOLS=(
+		"tcp"
+		"udp"
+		"uds"
+		"sctp"
+	)
+
+	ROLES=(
+		"client"
+		"server"
+	)
+
+	MODES=(
+		"stream"
+		"datagram"
 	)
 
 	if   [[ "$w1" == "--relation"                      && "x$w0" == "x" ]];    then COMPREPLY=("''")
-	elif [[ "$w1" == "--unlink-on-close"                                ]];    then COMPREPLY=($(compgen -W "${BOOLEAN_VALUES[*]}" -- "$w0"))
-	elif [[ "$w1" == "--queue"                         && "x$w0" == "x" ]];    then COMPREPLY=("''")
 	elif [[ "$w1" == "--message-count"                 && "x$w0" == "x" ]];    then COMPREPLY=("1")
+	elif [[ "$w1" == "--connection-string"                              ]];    then COMPREPLY=($(compgen -W "${CONNECTION_STRINGS[*]}" -- "$w0"))
+	elif [[ "$w1" == "--connection-option"                              ]];    then COMPREPLY=($(compgen -W "${OPTIONS[*]}" -- "$w0"))
+	elif [[ "$w2" == "--connection-option" && "$w1" == "protocol"       ]];    then COMPREPLY=($(compgen -W "${PROTOCOLS[*]}" -- "$w0"))
+	elif [[ "$w2" == "--connection-option" && "$w1" == "role"           ]];    then COMPREPLY=($(compgen -W "${ROLES[*]}" -- "$w0"))
+	elif [[ "$w2" == "--connection-option" && "$w1" == "mode"           ]];    then COMPREPLY=($(compgen -W "${MODES[*]}" -- "$w0"))
+	elif [[ "$w2" == "--connection-option" && "$w1" == "path"           ]];    then COMPREPLY=($(compgen -f -- "$w0"))
 	else
 		OPTIONS=(
 			"--relation"
-			"--unlink-on-close"
-			"--queue"
 			"--message-count"
+			"--connection-string"
+			"--connection-option"
 		)
 		COMPREPLY=($(compgen -W "${OPTIONS[*]}" -- "$w0"))
 	fi

--- a/nbproject/configurations.xml	Sun Aug 07 10:45:05 2022 +0200
+++ b/nbproject/configurations.xml	Sun Aug 21 00:16:50 2022 +0200
@@ -42,6 +42,7 @@
   <logicalFolder name="root" displayName="root" projectFiles="true" kind="ROOT">
     <df root="." name="0">
       <df name="src">
+        <in>Socket.cpp</in>
         <in>Socket.h</in>
         <in>SocketCommand.cpp</in>
         <in>relpipe-in-socket.cpp</in>
@@ -94,7 +95,9 @@
           <preBuildFirst>true</preBuildFirst>
         </preBuild>
       </makefileType>
-      <item path="src/Socket.h" ex="false" tool="3" flavor2="0">
+      <item path="src/Socket.cpp" ex="false" tool="1" flavor2="0">
+        <ccTool flags="0">
+        </ccTool>
       </item>
       <item path="src/SocketCommand.cpp" ex="false" tool="1" flavor2="0">
         <ccTool flags="0">

--- a/src/CLIParser.h	Sun Aug 07 10:45:05 2022 +0200
+++ b/src/CLIParser.h	Sun Aug 21 00:16:50 2022 +0200
@@ -18,8 +18,10 @@
 
 #include <vector>
 #include <iostream>
+#include <codecvt>
+#include <regex>
 
-#include <relpipe/writer/typedefs.h>
+#include <relpipe/common/type/typedefs.h>
 #include <relpipe/cli/CLI.h>
 #include <relpipe/cli/RelpipeCLIException.h>
 
@@ -31,8 +33,9 @@
 
 class CLIParser {
 private:
+	std::wstring_convert<codecvt_utf8<wchar_t>> convertor; // TODO: support also other encodings.
 
-	relpipe::writer::string_t readNext(const std::vector<relpipe::writer::string_t>& arguments, int& i) {
+	relpipe::common::type::StringX readNext(const std::vector<relpipe::common::type::StringX>& arguments, int& i) {
 		if (i < arguments.size()) return arguments[i++];
 		else throw relpipe::cli::RelpipeCLIException(L"Missing CLI argument" + (i > 0 ? (L" after " + arguments[i - 1]) : L""), relpipe::cli::CLI::EXIT_CODE_BAD_CLI_ARGUMENTS);
 	}
@@ -46,30 +49,68 @@
 		else throw relpipe::cli::RelpipeCLIException(L"Unable to parse boolean value: " + value + L" (expecting true or false)", relpipe::cli::CLI::EXIT_CODE_BAD_CLI_ARGUMENTS);
 	}
 
+	void setIfMissing(std::vector<Configuration::SocketOption>& options, const std::string& name, const std::string& value, bool includeEmptyValues = true) {
+		auto n = convertor.from_bytes(name);
+		auto v = convertor.from_bytes(value);
+		for (auto o : options) if (o.name == n) return;
+		if (value.size() || includeEmptyValues) options.push_back({n, v});
+	}
+
 public:
 
-	static const relpipe::writer::string_t OPTION_RELATION;
-	static const relpipe::writer::string_t OPTION_UNLINK_ON_CLOSE;
-	static const relpipe::writer::string_t OPTION_QUEUE;
+	static const relpipe::common::type::StringX OPTION_RELATION;
+	static const relpipe::common::type::StringX OPTION_CONNECTION_STRING;
+	static const relpipe::common::type::StringX OPTION_CONNECTION_OPTION;
 	static const relpipe::writer::string_t OPTION_MESSAGE_COUNT;
 
-	Configuration parse(const std::vector<relpipe::writer::string_t>& arguments) {
+	Configuration parse(const std::vector<relpipe::common::type::StringX>& arguments) {
 		Configuration c;
+		relpipe::common::type::StringX connectionString;
 
 		for (int i = 0; i < arguments.size();) {
-			relpipe::writer::string_t option = readNext(arguments, i);
+			relpipe::common::type::StringX option = readNext(arguments, i);
 
 			if (option == OPTION_RELATION) {
 				c.relation = readNext(arguments, i);
-			} else if (option == OPTION_UNLINK_ON_CLOSE) {
-				c.unlinkOnClose = parseBoolean(readNext(arguments, i));
-			} else if (option == OPTION_QUEUE) {
-				c.queue = readNext(arguments, i);
 			} else if (option == OPTION_MESSAGE_COUNT) {
 				c.messageCount = std::stoull(readNext(arguments, i));
+			} else if (option == OPTION_CONNECTION_STRING) {
+				connectionString = readNext(arguments, i);
+			} else if (option == OPTION_CONNECTION_OPTION) {
+				auto name = readNext(arguments, i);
+				auto value = readNext(arguments, i);
+				c.options.push_back({name, value});
 			} else throw relpipe::cli::RelpipeCLIException(L"Unsupported CLI option: " + option, relpipe::cli::CLI::EXIT_CODE_BAD_CLI_ARGUMENTS);
 		}
 
+		using namespace options;
+
+		// Parse the connection string and convert it to options:
+		if (connectionString.size()) {
+			std::string connectionStringBytes = convertor.to_bytes(connectionString);
+			std::regex pattern("(tcp|udp|sctp)://(([^:]+)|\\[([0-9a-fA-F:]+(%[a-zA-Z0-9]+)?)\\]):([0-9]+)|(uds)://(.*)");
+			//                  1                23          4             5                    6        7       8
+			std::smatch match;
+			if (std::regex_match(connectionStringBytes, match, pattern)) {
+				setIfMissing(c.options, OPTION_PROTOCOL, match[1], false);
+				setIfMissing(c.options, OPTION_PROTOCOL, match[7], false);
+				setIfMissing(c.options, OPTION_HOST, match[3], false);
+				setIfMissing(c.options, OPTION_HOST, match[4], false);
+				setIfMissing(c.options, OPTION_PORT, match[6], false);
+				setIfMissing(c.options, OPTION_PATH, match[8], false);
+				if (match[1] == PROTOCOL_TCP) setIfMissing(c.options, OPTION_MODE, MODE_STREAM);
+			} else {
+				throw relpipe::cli::RelpipeCLIException(L"Invalid connection string: " + connectionString, relpipe::cli::CLI::EXIT_CODE_BAD_CLI_ARGUMENTS);
+			}
+		}
+
+		// Set defaults when values are missing:
+		setIfMissing(c.options, OPTION_PROTOCOL, PROTOCOL_UDP);
+		setIfMissing(c.options, OPTION_ROLE, ROLE_SERVER);
+		setIfMissing(c.options, OPTION_MODE, MODE_DATAGRAM);
+		setIfMissing(c.options, OPTION_HOST, "127.0.0.1");
+		setIfMissing(c.options, OPTION_PORT, "64000");
+
 		return c;
 	}
 
@@ -77,9 +118,9 @@
 	}
 };
 
-const relpipe::writer::string_t CLIParser::OPTION_RELATION = L"--relation";
-const relpipe::writer::string_t CLIParser::OPTION_UNLINK_ON_CLOSE = L"--unlink-on-close";
-const relpipe::writer::string_t CLIParser::OPTION_QUEUE = L"--queue";
+const relpipe::common::type::StringX CLIParser::OPTION_RELATION = L"--relation";
+const relpipe::common::type::StringX CLIParser::OPTION_CONNECTION_STRING = L"--connection-string";
+const relpipe::common::type::StringX CLIParser::OPTION_CONNECTION_OPTION = L"--connection-option";
 const relpipe::writer::string_t CLIParser::OPTION_MESSAGE_COUNT = L"--message-count";
 
 }

--- a/src/CMakeLists.txt	Sun Aug 07 10:45:05 2022 +0200
+++ b/src/CMakeLists.txt	Sun Aug 21 00:16:50 2022 +0200
@@ -30,6 +30,7 @@
 add_executable(
 	${EXECUTABLE_FILE}
 	SocketCommand.cpp
+	Socket.cpp
 	relpipe-in-socket.cpp
 )
 

--- a/src/Configuration.h	Sun Aug 07 10:45:05 2022 +0200
+++ b/src/Configuration.h	Sun Aug 21 00:16:50 2022 +0200
@@ -21,6 +21,7 @@
 
 #include <relpipe/common/type/typedefs.h>
 
+#include "Socket.h"
 
 namespace relpipe {
 namespace in {
@@ -29,10 +30,20 @@
 class Configuration {
 public:
 
+	class SocketOption {
+	public:
+		const relpipe::common::type::StringX name;
+		const relpipe::common::type::StringX value;
+
+		SocketOption(const relpipe::common::type::StringX name, const relpipe::common::type::StringX value) : name(name), value(value) {
+		}
+
+		virtual ~SocketOption() = default;
+	};
+
 	relpipe::common::type::Integer messageCount = 1;
 	relpipe::common::type::StringX relation = L"message";
-	relpipe::common::type::StringX queue = L"/relpipe";
-	relpipe::common::type::Boolean unlinkOnClose = false;
+	std::vector<SocketOption> options;
 
 	virtual ~Configuration() {
 	}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Socket.cpp	Sun Aug 21 00:16:50 2022 +0200
@@ -0,0 +1,412 @@
+/**
+ * Relational pipes
+ * Copyright © 2022 František Kučera (Frantovo.cz, GlobalCode.info)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <string>
+#include <cstring>
+#include <unistd.h>
+#include <stdexcept>
+#include <arpa/inet.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <netinet/in.h>
+#include <vector>
+#include <memory>
+#include <regex>
+#include <iostream>
+#include <netdb.h>
+
+#include "Socket.h"
+
+namespace relpipe {
+namespace in {
+namespace socket {
+
+using namespace relpipe::in::socket::options;
+
+static const std::string findOption(SocketOptions options, std::string name, bool required = false, const std::string defaultValue = "") {
+	for (auto o : options) if (o.name == name) return o.value;
+	if (required) throw std::invalid_argument("Option " + name + " is required but was not found");
+	else return defaultValue;
+}
+
+class FD {
+private:
+	int fd;
+public:
+
+	FD(int fd) : fd(fd) {
+	};
+
+	virtual ~FD() {
+		close(fd);
+	}
+
+	int getFD() {
+		return fd;
+	}
+};
+
+static void check(int result, std::string message) {
+	if (result == 0); // OK
+	else throw std::logic_error("Got error result: " + message + ": " + strerror(errno) + " (result=" + std::to_string(result) + ", errno=" + std::to_string(errno) + ")");
+}
+
+class AddressInfos {
+private:
+	std::shared_ptr<addrinfo> addrInfo;
+
+	AddressInfos(addrinfo* addrInfo) : addrInfo(std::shared_ptr<addrinfo>(addrInfo, freeaddrinfo)) {
+	}
+
+public:
+
+	virtual ~AddressInfos() {
+	}
+
+	class AddressInfo {
+	private:
+		std::shared_ptr<addrinfo> parent; // to avoid premature deletion of the whole structure
+	public:
+		const addrinfo * const ai;
+
+		AddressInfo(const addrinfo * const ai, std::shared_ptr<addrinfo> parent) : ai(ai), parent(parent) {
+		}
+
+		const std::string toString() const {
+			char buffer[INET6_ADDRSTRLEN] = {0};
+			if (ai->ai_family == AF_INET) return inet_ntop(ai->ai_family, &((sockaddr_in const *) ai->ai_addr)->sin_addr, buffer, sizeof (buffer)); // TODO: check 0 result
+			else if (ai->ai_family == AF_INET6) return inet_ntop(ai->ai_family, &((sockaddr_in6 const *) ai->ai_addr)->sin6_addr, buffer, sizeof (buffer)); // TODO: check 0 result
+			else return "unknown address family: " + std::to_string(ai->ai_family);
+		}
+	};
+
+	static AddressInfos getAddressInfos(const std::string& host, const std::string& port, int socketType = SOCK_STREAM, int protocol = IPPROTO_TCP) {
+		struct addrinfo query;
+		memset(&query, sizeof (query), 0);
+		query.ai_family = AF_UNSPEC;
+		query.ai_socktype = socketType;
+		query.ai_protocol = protocol;
+		query.ai_flags = AI_ALL;
+
+		struct addrinfo* addrInfo;
+		check(getaddrinfo(host.c_str(), port.c_str(), &query, &addrInfo), "getaddrinfo");
+
+		return AddressInfos(addrInfo);
+	}
+
+	const std::size_t size() const {
+		std::size_t size = 0;
+		for (addrinfo* ai = addrInfo.get(); ai; ai = ai->ai_next) size++;
+		return size;
+	}
+
+	const AddressInfo operator[](std::size_t index) const {
+		for (addrinfo* ai = addrInfo.get(); ai; index--) {
+			if (index == 0) return AddressInfo(ai, addrInfo);
+			else ai = ai->ai_next;
+		}
+
+		throw std::out_of_range("invalid index for AddressInfo: " + std::to_string(index));
+	}
+
+};
+
+template<class SocketClass, class... MoreArgs> static std::shared_ptr<SocketClass> openClientSocket(const SocketOptions& options, int socketType, int protocol, MoreArgs... moreArgs) {
+	AddressInfos remoteAddresses = AddressInfos::getAddressInfos(
+			findOption(options, OPTION_HOST, true),
+			findOption(options, OPTION_PORT, true),
+			socketType,
+			protocol);
+
+	return std::shared_ptr<SocketClass>(new SocketClass(remoteAddresses[0], moreArgs...));
+}
+
+/**
+ * abstract class for sockets that use sendmsg() / recvmsg()
+ */
+class MSGSocket : public Socket {
+protected:
+	FD socket;
+
+	void sendmsg(const std::string& message) {
+		iovec iov[1];
+		msghdr msg = {};
+		msg.msg_iov = iov;
+		msg.msg_iov[0].iov_base = (void*) message.c_str();
+		msg.msg_iov[0].iov_len = message.size();
+		msg.msg_iovlen = sizeof (iov) / sizeof (iov[0]);
+		ssize_t written = ::sendmsg(socket.getFD(), &msg, 0);
+		if (written != message.size()) throw std::logic_error("writing to the socket failed");
+	}
+public:
+
+	MSGSocket(int socket) : socket(socket) {
+	}
+
+	void send(const OutgoingMessage& message) {
+		sendmsg(message.data);
+	}
+
+};
+
+class UDPClientSocket : public Socket {
+private:
+	AddressInfos::AddressInfo remoteAddress;
+	useconds_t delay = 0;
+	FD socket;
+
+public:
+
+	UDPClientSocket(AddressInfos::AddressInfo remoteAddress) : remoteAddress(remoteAddress), socket(::socket(remoteAddress.ai->ai_family, remoteAddress.ai->ai_socktype, remoteAddress.ai->ai_protocol)) {
+	}
+
+	static std::shared_ptr<Socket> open(const SocketOptions& options) {
+		auto socket = openClientSocket<UDPClientSocket>(options, SOCK_DGRAM, IPPROTO_UDP);
+		socket->delay = std::stol(findOption(options, OPTION_DELAY, false, "0")); // TODO: Move to SocketHandler? Or delete.
+		return socket;
+	}
+
+	void send(const OutgoingMessage& message) override {
+		auto ai = remoteAddress.ai;
+		sendto(socket.getFD(), message.data.c_str(), message.data.size(), 0, ai->ai_addr, ai->ai_addrlen);
+		if (delay) usleep(delay);
+	}
+
+	const IncomingMessage receive() override {
+		// TODO: UDP receive()
+		return IncomingMessage("TODO: receive() a message");
+	}
+};
+
+class UDPServerSocket : public Socket {
+private:
+	AddressInfos::AddressInfo localAddress;
+	sockaddr_in6 remoteAddressForSending = {};
+	useconds_t delay = 0;
+	FD socket;
+
+public:
+
+	UDPServerSocket(AddressInfos::AddressInfo remoteAddress) : localAddress(remoteAddress), socket(::socket(remoteAddress.ai->ai_family, remoteAddress.ai->ai_socktype, remoteAddress.ai->ai_protocol)) {
+	}
+
+	static std::shared_ptr<Socket> open(const SocketOptions& options) {
+		auto socket = openClientSocket<UDPServerSocket>(options, SOCK_DGRAM, IPPROTO_UDP);
+		auto ai = socket->localAddress.ai;
+		int reuseAddr = true;
+		check(::setsockopt(socket->socket.getFD(), SOL_SOCKET, SO_REUSEADDR, &reuseAddr, sizeof (reuseAddr)), "setsockopt SO_REUSEADDR");
+		check(::bind(socket->socket.getFD(), ai->ai_addr, ai->ai_addrlen), "bind");
+		return socket;
+	}
+
+	void send(const OutgoingMessage& message) override {
+		// receive a message first to get a remote address:
+		char buffer[8192];
+		memset((char *) &remoteAddressForSending, 0, sizeof (remoteAddressForSending));
+		socklen_t remoteAddressSize = sizeof (remoteAddressForSending);
+		ssize_t msgSize = recvfrom(socket.getFD(), buffer, sizeof (buffer), 0, (sockaddr*) & remoteAddressForSending, &remoteAddressSize);
+
+		// respond with our messsage:
+		sendto(socket.getFD(), message.data.c_str(), message.data.size(), 0, (sockaddr*) & remoteAddressForSending, remoteAddressSize);
+	}
+
+	const IncomingMessage receive() override {
+		char buffer[8192];
+		sockaddr_in6 remoteAddress;
+		memset((char *) &remoteAddress, 0, sizeof (remoteAddress));
+		socklen_t remoteAddressSize = sizeof (remoteAddress);
+		ssize_t msgSize = recvfrom(socket.getFD(), buffer, sizeof (buffer), 0, (sockaddr*) & remoteAddress, &remoteAddressSize);
+		check(msgSize < 0, "recvfrom");
+
+		IncomingMessage message(std::string(buffer, std::min(sizeof (buffer), (size_t) msgSize)));
+
+		// TODO: move to a common method
+		char hostBuffer[INET6_ADDRSTRLEN] = {0};
+		if (remoteAddress.sin6_family == AF_INET) {
+			sockaddr_in* remoteAddress4 = (sockaddr_in*) & remoteAddress;
+			message.remoteHost = inet_ntop(remoteAddress4->sin_family, &remoteAddress4->sin_addr, hostBuffer, sizeof (hostBuffer)); // TODO: check 0 result
+			message.remotePort = remoteAddress4->sin_port;
+		} else if (remoteAddress.sin6_family == AF_INET6) {
+			message.remoteHost = inet_ntop(remoteAddress.sin6_family, &remoteAddress.sin6_addr, hostBuffer, sizeof (hostBuffer)); // TODO: check 0 result
+			message.remotePort = remoteAddress.sin6_port;
+		}
+
+		return message;
+	}
+};
+
+class TCPClientSocket : public Socket {
+private:
+	AddressInfos::AddressInfo remoteAddress;
+
+public:
+
+	TCPClientSocket(AddressInfos::AddressInfo remoteAddress) : remoteAddress(remoteAddress) {
+	}
+
+	static std::shared_ptr<Socket> open(const SocketOptions& options) {
+		return openClientSocket<TCPClientSocket>(options, SOCK_STREAM, IPPROTO_TCP);
+	}
+
+	void send(const OutgoingMessage& message) override {
+		auto ai = remoteAddress.ai;
+		FD s(::socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol));
+		check(::connect(s.getFD(), ai->ai_addr, ai->ai_addrlen), "connect socket");
+		ssize_t written = ::write(s.getFD(), message.data.c_str(), message.data.size());
+		if (written != message.data.size()) throw std::logic_error("writing to the socket failed");
+		// TODO: partial writes, repeat
+	}
+
+	const IncomingMessage receive() override {
+		// TODO: TCP receive()
+		return IncomingMessage("TODO: receive() a message");
+	}
+};
+
+class TCPServerSocket : public Socket {
+private:
+	AddressInfos::AddressInfo localAddress;
+	FD socket;
+public:
+
+	TCPServerSocket(AddressInfos::AddressInfo localAddress) : localAddress(localAddress), socket(::socket(localAddress.ai->ai_family, localAddress.ai->ai_socktype, localAddress.ai->ai_protocol)) {
+	}
+
+	static std::shared_ptr<Socket> open(const SocketOptions& options) {
+		auto socket = openClientSocket<TCPServerSocket>(options, SOCK_STREAM, IPPROTO_TCP);
+		auto ai = socket->localAddress.ai;
+		int reuseAddr = true;
+		check(::setsockopt(socket->socket.getFD(), SOL_SOCKET, SO_REUSEADDR, &reuseAddr, sizeof (reuseAddr)), "setsockopt SO_REUSEADDR");
+		check(::bind(socket->socket.getFD(), ai->ai_addr, ai->ai_addrlen), "bind");
+		check(::listen(socket->socket.getFD(), 10), "listen"); // TODO: configurable backlog connection count?
+		return socket;
+	}
+
+	void send(const OutgoingMessage& message) override {
+		FD clientSocket(accept(socket.getFD(), nullptr, 0));
+		ssize_t written = ::write(clientSocket.getFD(), message.data.c_str(), message.data.size());
+		if (written != message.data.size()) throw std::logic_error("writing to the socket failed");
+		// TODO: partial writes, repeat
+	}
+
+	const IncomingMessage receive() override {
+		// TODO: TCP receive()
+		return IncomingMessage("TODO: receive() a message");
+	}
+};
+
+class SCTPClientSocket : public MSGSocket {
+private:
+	AddressInfos::AddressInfo remoteAddress;
+public:
+
+	SCTPClientSocket(AddressInfos::AddressInfo remoteAddress) : remoteAddress(remoteAddress), MSGSocket(::socket(remoteAddress.ai->ai_family, remoteAddress.ai->ai_socktype, remoteAddress.ai->ai_protocol)) {
+	}
+
+	static std::shared_ptr<Socket> open(const SocketOptions& options) {
+		auto socket = openClientSocket<SCTPClientSocket>(options, SOCK_STREAM, IPPROTO_SCTP);
+		check(::connect(socket->socket.getFD(), socket->remoteAddress.ai->ai_addr, socket->remoteAddress.ai->ai_addrlen), "connect socket");
+		return socket;
+	}
+
+	const IncomingMessage receive() override {
+		// TODO: SCTP receive()
+		return IncomingMessage("TODO: receive() a message");
+	}
+};
+
+class UDSClientSocket : public MSGSocket {
+public:
+
+	UDSClientSocket(int fd) : MSGSocket(fd) {
+	}
+
+	static std::shared_ptr<Socket> open(const SocketOptions& options) {
+		struct sockaddr_un address;
+		std::string path = findOption(options, OPTION_PATH);
+
+		memset(&address, 0x00, sizeof (address));
+		address.sun_family = AF_UNIX;
+		strncpy(address.sun_path, path.c_str(), path.size());
+
+		int fd = ::socket(AF_UNIX, SOCK_STREAM, 0);
+
+		auto socket = std::make_shared<UDSClientSocket>(fd);
+		check(::connect(socket->socket.getFD(), (const sockaddr*) &address, sizeof (address)), "connect socket");
+
+
+		if (findOption(options, "debug") == "true") { // TODO: undocumented feature → standardize or remove
+			struct ucred credentials;
+			socklen_t credentialsLength = sizeof (credentials);
+			memset(&credentials, 0x00, credentialsLength);
+			getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &credentials, &credentialsLength);
+
+			printf("uds.fd = %d\n", fd);
+			printf("uds.path = %s\n", address.sun_path);
+			printf("uds.server.pid = %d\n", credentials.pid);
+			printf("uds.server.uid = %d\n", credentials.uid);
+			printf("uds.server.gid = %d\n", credentials.gid);
+		}
+
+
+		return socket;
+	}
+
+	const IncomingMessage receive() override {
+		// TODO: UDS receive()
+		return IncomingMessage("TODO: receive() a message");
+	}
+};
+
+template<const char* protocol, const char* role, const char* mode, typename SocketClass>
+class TemplateSocketFactory : public SocketFactory {
+public:
+
+	bool canHandle(const SocketOptions& options) override {
+		return findOption(options, OPTION_PROTOCOL) == protocol
+				&& findOption(options, OPTION_ROLE) == role
+				&& findOption(options, OPTION_MODE) == mode;
+	}
+
+	std::shared_ptr<Socket> open(const SocketOptions& options) override {
+		return SocketClass::open(options);
+	}
+};
+
+static std::vector<std::shared_ptr<SocketFactory>> factories
+{
+	std::make_shared<TemplateSocketFactory<PROTOCOL_TCP, ROLE_CLIENT, MODE_STREAM, TCPClientSocket >> (),
+	std::make_shared<TemplateSocketFactory<PROTOCOL_TCP, ROLE_SERVER, MODE_STREAM, TCPServerSocket >> (),
+	std::make_shared<TemplateSocketFactory<PROTOCOL_UDP, ROLE_CLIENT, MODE_DATAGRAM, UDPClientSocket >> (),
+	std::make_shared<TemplateSocketFactory<PROTOCOL_UDP, ROLE_SERVER, MODE_DATAGRAM, UDPServerSocket >> (),
+	std::make_shared<TemplateSocketFactory<PROTOCOL_SCTP, ROLE_CLIENT, MODE_STREAM, SCTPClientSocket >> (),
+	std::make_shared<TemplateSocketFactory<PROTOCOL_SCTP, ROLE_SERVER, MODE_STREAM, UDPClientSocket >> (), // TODO: correct class
+	std::make_shared<TemplateSocketFactory<PROTOCOL_UDS, ROLE_CLIENT, MODE_STREAM, UDSClientSocket >> (),
+	std::make_shared<TemplateSocketFactory<PROTOCOL_UDS, ROLE_CLIENT, MODE_DATAGRAM, UDSClientSocket >> (), // TODO: correct class
+	std::make_shared<TemplateSocketFactory<PROTOCOL_UDS, ROLE_SERVER, MODE_STREAM, UDSClientSocket >> (), // TODO: correct class
+	std::make_shared<TemplateSocketFactory<PROTOCOL_UDS, ROLE_SERVER, MODE_DATAGRAM, UDSClientSocket >> (), // TODO: correct class
+};
+
+std::shared_ptr<SocketFactory> SocketFactory::find(const SocketOptions& options) {
+	for (auto f : factories) if (f->canHandle(options)) return f;
+	throw std::logic_error("Unable to find a SocketFactory"); // TODO: add relevant options?
+}
+
+
+}
+}
+}

--- a/src/Socket.h	Sun Aug 07 10:45:05 2022 +0200
+++ b/src/Socket.h	Sun Aug 21 00:16:50 2022 +0200
@@ -17,6 +17,7 @@
 #pragma once
 
 #include <string>
+#include <vector>
 #include <cstring>
 #include <unistd.h>
 #include <stdexcept>
@@ -29,55 +30,92 @@
 namespace in {
 namespace socket {
 
-class Socket {
-private:
-	const static size_t MSG_SIZE = 8192; // TODO: configurable/dynamic
-	int s = ::socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+namespace options {
+static const char OPTION_PROTOCOL[] = "protocol";
+static const char OPTION_ROLE[] = "role";
+static const char OPTION_MODE[] = "mode";
+static const char OPTION_HOST[] = "host";
+static const char OPTION_PORT[] = "port";
+static const char OPTION_PATH[] = "path";
+static const char OPTION_DELAY[] = "delay";
+
+static const char PROTOCOL_TCP[] = "tcp";
+static const char PROTOCOL_UDP[] = "udp";
+static const char PROTOCOL_UDS[] = "uds";
+static const char PROTOCOL_SCTP[] = "sctp";
+
+static const char ROLE_CLIENT[] = "client";
+static const char ROLE_SERVER[] = "server";
 
+static const char MODE_STREAM[] = "stream";
+static const char MODE_DATAGRAM[] = "datagram";
+}
+
+class Message {
+public:
+	std::string data;
+
+	Message() {
+	}
+
+	Message(const std::string& data) : data(data) {
+	}
+
+	virtual ~Message() = default;
+
+
+};
+
+class IncomingMessage : public Message {
 public:
 
-	Socket() {
-		s = ::socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
-
-		struct sockaddr_in a;
-		memset((char *) &a, 0, sizeof (a));
-		a.sin_family = AF_INET;
-		a.sin_addr.s_addr = inet_addr("127.0.0.1"); // TODO: use getaddrinfo() instead (because of error -1 = 255.255.255.255)
-		a.sin_port = htons(1234);
-		::bind(s, (sockaddr*) & a, sizeof (a));
-
-		// int soBufferSize = 1024 * 1024;
-		// setsockopt(s, SOL_SOCKET, SO_RCVBUF, &soBufferSize, sizeof (soBufferSize));
-		// soBufferSize = 0;
-		// socklen_t soBufferSizeLength = sizeof (soBufferSize);
-
-		// std::cerr << "soBufferSize=" << soBufferSize << std::endl;
-		// getsockopt(s, SOL_SOCKET, SO_RCVBUF, &soBufferSize, &soBufferSizeLength);
-		// std::cerr << "soBufferSize=" << soBufferSize << " length=" << soBufferSizeLength << std::endl;
+	IncomingMessage(const std::string& data) : Message(data) {
 	}
 
-	virtual ~Socket() {
-		close(s);
-	}
-
-	std::string receive() {
-		char buffer[MSG_SIZE + 1];
-		memset(buffer, 0, MSG_SIZE + 1);
+	std::string remoteHost;
+	in_port_t remotePort = 0;
+	pid_t remotePID = 0;
+	uid_t remoteUID = 0;
+	gid_t remoteGID = 0;
+};
 
-		struct sockaddr_in remoteAddress;
-		memset((char *) &remoteAddress, 0, sizeof (remoteAddress));
-		socklen_t remoteAddressSize = sizeof (remoteAddress);
+class OutgoingMessage : public Message {
+public:
 
-		ssize_t msgSize = recvfrom(s, buffer, sizeof (buffer), 0, (sockaddr*) & remoteAddress, &remoteAddressSize);
-
-
-		if (msgSize > sizeof (buffer))throw std::logic_error("Invalid Socket message size.");
-		else if (msgSize >= 0) return std::string(buffer, msgSize);
-		else throw std::logic_error("Unable to receive Socket message the socket; error: " + std::string(strerror(errno)));
+	OutgoingMessage(const std::string& data) : Message(data) {
 	}
 
 };
 
+class Socket {
+public:
+	virtual ~Socket() = default;
+	virtual void send(const OutgoingMessage& message) = 0;
+	virtual const IncomingMessage receive() = 0;
+};
+
+class SocketOption {
+public:
+	const std::string name;
+	const std::string value;
+
+	SocketOption(const std::string name, const std::string value) : name(name), value(value) {
+	}
+
+	virtual ~SocketOption() = default;
+};
+
+using SocketOptions = std::vector<SocketOption>;
+
+class SocketFactory {
+public:
+	virtual ~SocketFactory() = default;
+	virtual bool canHandle(const SocketOptions& options) = 0;
+	virtual std::shared_ptr<Socket> open(const SocketOptions& options) = 0;
+	static std::shared_ptr<SocketFactory> find(const SocketOptions& options);
+};
+
+
 }
 }
 }

--- a/src/SocketCommand.cpp	Sun Aug 07 10:45:05 2022 +0200
+++ b/src/SocketCommand.cpp	Sun Aug 21 00:16:50 2022 +0200
@@ -47,21 +47,31 @@
 void SocketCommand::process(std::shared_ptr<writer::RelationalWriter> writer, Configuration& configuration) {
 	vector<AttributeMetadata> metadata;
 
-	std::shared_ptr<Socket> socket = std::make_shared<Socket>(); // TODO: create a TCP, UDP… socket
+	std::vector<SocketOption> options;
+	for (auto o : configuration.options) options.push_back({convertor.to_bytes(o.name), convertor.to_bytes(o.value)});
+	std::shared_ptr<Socket> socket = SocketFactory::find(options)->open(options);
 
 	writer->startRelation(configuration.relation,{
-		{L"queue", TypeId::STRING},
+		{L"host", TypeId::STRING},
+		{L"port", TypeId::INTEGER},
+		{L"pid", TypeId::INTEGER},
+		{L"gid", TypeId::INTEGER},
+		{L"uid", TypeId::INTEGER},
 		{L"text", TypeId::STRING},
 		{L"data", TypeId::STRING}
 	}, true);
 
 	for (int i = configuration.messageCount; continueProcessing && i > 0; i--) {
 		// TODO: maybe rather call mq_timedreceive() inside and check continueProcessing (to be able to stop even when no messages are comming)
-		std::string message = socket->receive();
+		IncomingMessage message = socket->receive();
 
-		writer->writeAttribute(configuration.queue);
-		writer->writeAttribute(Hex::toTxt(message));
-		writer->writeAttribute(Hex::toHex(message));
+		writer->writeAttribute(convertor.from_bytes(message.remoteHost));
+		writer->writeAttribute(std::to_wstring(message.remotePort));
+		writer->writeAttribute(std::to_wstring(message.remotePID));
+		writer->writeAttribute(std::to_wstring(message.remoteGID));
+		writer->writeAttribute(std::to_wstring(message.remoteUID));
+		writer->writeAttribute(Hex::toTxt(message.data));
+		writer->writeAttribute(Hex::toHex(message.data));
 	}
 
 }