--- a/src/CLIParser.h	Sat Mar 20 19:18:10 2021 +0100
+++ b/src/CLIParser.h	Fri Mar 26 22:29:46 2021 +0100
@@ -37,17 +37,6 @@
 		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);
 	}
 
-	void readNextRecord(const std::vector<relpipe::common::type::StringX>& arguments, int& i, RelationConfiguration& currentRelation) {
-		for (const auto& a : currentRelation.attributes) currentRelation.values.emplace_back(readNext(arguments, i));
-	}
-
-	void addRelation(Configuration& c, RelationConfiguration& currentRelation) {
-		if (currentRelation.relation.size()) {
-			c.relationConfigurations.push_back(currentRelation);
-			currentRelation = RelationConfiguration();
-		}
-	}
-
 	/**
 	 * TODO: use a common method
 	 */
@@ -57,58 +46,23 @@
 		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);
 	}
 
-	/**
-	 * TODO: use a common method
-	 */
-	relpipe::writer::TypeId parseTypeId(const relpipe::common::type::StringX& value) {
-		using t = relpipe::writer::TypeId;
-		if (value == L"string") return t::STRING;
-		else if (value == L"integer") return t::INTEGER;
-		else if (value == L"boolean") return t::BOOLEAN;
-		else throw relpipe::cli::RelpipeCLIException(L"Unable to parse TypeId: " + value, relpipe::cli::CLI::EXIT_CODE_BAD_CLI_ARGUMENTS);
-	}
-
 public:
 
-	static const relpipe::common::type::StringX OPTION_RELATION;
-	static const relpipe::common::type::StringX OPTION_WRITE_HEADER;
-	static const relpipe::common::type::StringX OPTION_ATTRIBUTE;
-	static const relpipe::common::type::StringX OPTION_RECORD;
-	static const relpipe::common::type::StringX OPTION_RECORDS;
-	static const relpipe::common::type::StringX OPTION_RECORDS_STDIN;
+	static const relpipe::common::type::StringX OPTION_LIST_INPUT_DEVICES;
+	static const relpipe::common::type::StringX OPTION_LIST_INPUT_EVENTS;
 
 	Configuration parse(const std::vector<relpipe::common::type::StringX>& arguments) {
 		Configuration c;
-		RelationConfiguration currentRelation;
 
 		for (int i = 0; i < arguments.size();) {
 			relpipe::common::type::StringX option = readNext(arguments, i);
 
-			if (option == OPTION_RELATION) {
-				addRelation(c, currentRelation); // previous relation
-				currentRelation.relation = readNext(arguments, i);
-			} else if (option == OPTION_WRITE_HEADER) {
-				currentRelation.writeHeader = parseBoolean(readNext(arguments, i));
-			} else if (option == OPTION_ATTRIBUTE) {
-				AttributeRecipe attribute;
-				attribute.name = readNext(arguments, i);
-				attribute.type = parseTypeId(readNext(arguments, i));
-				currentRelation.attributes.push_back(attribute);
-			} else if (option == OPTION_RECORD) {
-				readNextRecord(arguments, i, currentRelation);
-			} else if (option == OPTION_RECORDS) {
-				while (i < arguments.size()) readNextRecord(arguments, i, currentRelation);
-			} else if (option == OPTION_RECORDS_STDIN) {
-				if (parseBoolean(readNext(arguments, i))) {
-					for (RelationConfiguration r : c.relationConfigurations) if (r.valueStream) throw relpipe::cli::RelpipeCLIException(L"Only one relation can read data from STDIN.", relpipe::cli::CLI::EXIT_CODE_BAD_CLI_ARGUMENTS);
-					currentRelation.valueStream = &std::cin;
-				}
+			if (option == OPTION_LIST_INPUT_DEVICES) {
+				c.listInputDevices = parseBoolean(readNext(arguments, i));
+			} else if (option == OPTION_LIST_INPUT_EVENTS) {
+				c.listInputEvents = parseBoolean(readNext(arguments, i));
 			} else throw relpipe::cli::RelpipeCLIException(L"Unsupported CLI option: " + option, relpipe::cli::CLI::EXIT_CODE_BAD_CLI_ARGUMENTS);
 		}
-		addRelation(c, currentRelation); // last relation
-
-		if (c.relationConfigurations.size() == 0) throw relpipe::cli::RelpipeCLIException(L"There must be at least one relation. Use the " + OPTION_RELATION + L" option.", relpipe::cli::CLI::EXIT_CODE_BAD_CLI_ARGUMENTS);
-		for (auto& rc : c.relationConfigurations) if (rc.attributes.size() == 0) throw relpipe::cli::RelpipeCLIException(L"There must be at least one attribute. Use the " + OPTION_ATTRIBUTE + L" option.", relpipe::cli::CLI::EXIT_CODE_BAD_CLI_ARGUMENTS);
 
 		return c;
 	}
@@ -117,12 +71,8 @@
 	}
 };
 
-const relpipe::common::type::StringX CLIParser::OPTION_RELATION = L"--relation";
-const relpipe::common::type::StringX CLIParser::OPTION_WRITE_HEADER = L"--write-header";
-const relpipe::common::type::StringX CLIParser::OPTION_ATTRIBUTE = L"--attribute";
-const relpipe::common::type::StringX CLIParser::OPTION_RECORD = L"--record";
-const relpipe::common::type::StringX CLIParser::OPTION_RECORDS = L"--records";
-const relpipe::common::type::StringX CLIParser::OPTION_RECORDS_STDIN = L"--records-on-stdin";
+const relpipe::common::type::StringX CLIParser::OPTION_LIST_INPUT_DEVICES = L"--list-input-devices";
+const relpipe::common::type::StringX CLIParser::OPTION_LIST_INPUT_EVENTS = L"--list-input-events";
 
 }
 }

--- a/src/CMakeLists.txt	Sat Mar 20 19:18:10 2021 +0100
+++ b/src/CMakeLists.txt	Fri Mar 26 22:29:46 2021 +0100
@@ -17,7 +17,7 @@
 
 # Relpipe libraries:
 INCLUDE(FindPkgConfig)
-pkg_check_modules (RELPIPE_LIBS relpipe-lib-writer.cpp relpipe-lib-cli.cpp)
+pkg_check_modules (RELPIPE_LIBS relpipe-lib-writer.cpp relpipe-lib-cli.cpp x11 xi xtst)
 include_directories(${RELPIPE_LIBS_INCLUDE_DIRS})
 link_directories(${RELPIPE_LIBS_LIBRARY_DIRS})
 

--- a/src/Configuration.h	Sat Mar 20 19:18:10 2021 +0100
+++ b/src/Configuration.h	Fri Mar 26 22:29:46 2021 +0100
@@ -26,33 +26,10 @@
 namespace in {
 namespace x11 {
 
-class AttributeRecipe {
-public:
-
-	virtual ~AttributeRecipe() {
-	}
-
-	relpipe::common::type::StringX name;
-	relpipe::writer::TypeId type;
-
-};
-
-class RelationConfiguration {
-public:
-
-	virtual ~RelationConfiguration() {
-	}
-
-	relpipe::common::type::StringX relation;
-	relpipe::common::type::Boolean writeHeader = true;
-	std::vector<AttributeRecipe> attributes;
-	std::vector<relpipe::common::type::StringX> values;
-	std::istream* valueStream = nullptr;
-};
-
 class Configuration {
 public:
-	std::vector<RelationConfiguration> relationConfigurations;
+	bool listInputDevices = true;
+	bool listInputEvents = false;
 
 	virtual ~Configuration() {
 	}

--- a/src/X11Command.h	Sat Mar 20 19:18:10 2021 +0100
+++ b/src/X11Command.h	Fri Mar 26 22:29:46 2021 +0100
@@ -19,6 +19,9 @@
 #include <codecvt>
 #include <memory>
 #include <iostream>
+#include <stdexcept>
+
+#include <X11/extensions/XInput.h>
 
 #include "Configuration.h"
 
@@ -29,43 +32,72 @@
 class X11Command {
 private:
 
+	class Display {
+	public:
+		::Display* display = nullptr;
+		// TODO: more OOP
+
+		virtual ~Display() {
+			if (display) XCloseDisplay(display);
+		}
+
+	};
+
+	class DeviceList {
+	public:
+		XDeviceInfo* items = nullptr;
+		int count = 0;
+		// TODO: more OOP
+
+		virtual ~DeviceList() {
+			if (items) XFreeDeviceList(items);
+		}
+
+	};
+
+
 	std::wstring_convert<codecvt_utf8<wchar_t>> convertor; // TODO: support also other encodings and use platform encoding as default
 
-	void processRelation(RelationConfiguration& configuration, std::shared_ptr<writer::RelationalWriter> writer) {
-		// Write header / metadata:
-		std::vector<relpipe::writer::AttributeMetadata> attributesMetadata;
-		for (AttributeRecipe ar : configuration.attributes) attributesMetadata.push_back({ar.name, ar.type});
-		writer->startRelation(configuration.relation, attributesMetadata, configuration.writeHeader);
+	void listInputDevices(Display& display, Configuration& configuration, std::shared_ptr<writer::RelationalWriter> writer) {
+		writer->startRelation(L"x11_input_device",{
+			{L"id", relpipe::writer::TypeId::INTEGER},
+			{L"name", relpipe::writer::TypeId::STRING},
+			// TODO: device type name and ID
+		}, true);
 
-		// Write records from CLI:
-		for (auto value : configuration.values) writer->writeAttribute(value);
+		DeviceList devices;
+		devices.items = XListInputDevices(display.display, &devices.count);
 
-		// Write records from STDIN:
-		if (configuration.valueStream) {
-			std::stringstream rawValue;
-			while (true) {
-				char ch = 0;
-				configuration.valueStream->get(ch);
-				if (ch == 0 && configuration.valueStream->good()) {
-					writer->writeAttribute(convertor.from_bytes(rawValue.str()));
-					rawValue.str("");
-					rawValue.clear();
-				} else if (configuration.valueStream->good()) {
-					rawValue << ch;
-				} else if (configuration.valueStream->eof()) {
-					return;
-				} else {
-					throw relpipe::cli::RelpipeCLIException(L"Error while reading values from the input stream.", relpipe::cli::CLI::EXIT_CODE_UNEXPECTED_ERROR); // TODO: better exception
-				}
-			}
+		for (int i = 0; i < devices.count; i++) {
+			relpipe::common::type::Integer id = (devices.items + i)->id;
+			relpipe::common::type::StringX name = convertor.from_bytes((devices.items + i)->name);
+
+			writer->writeAttribute(&id, typeid (id));
+			writer->writeAttribute(&name, typeid (name));
+
 		}
+	}
 
+	void listInputEvents(Display& display, Configuration& configuration, std::shared_ptr<writer::RelationalWriter> writer) {
+		writer->startRelation(L"x11_input_event",{
+			{L"device_id", relpipe::writer::TypeId::INTEGER},
+		}, true);
+
+		// TODO: list events
 	}
 
 public:
 
 	void process(Configuration& configuration, std::shared_ptr<writer::RelationalWriter> writer) {
-		for (RelationConfiguration& relationConfiguration : configuration.relationConfigurations) processRelation(relationConfiguration, writer);
+		Display display;
+		display.display = XOpenDisplay(nullptr);
+
+		if (display.display) {
+			if (configuration.listInputDevices) listInputDevices(display, configuration, writer);
+			if (configuration.listInputEvents) listInputEvents(display, configuration, writer);
+		} else {
+			throw std::invalid_argument("Unable to open display. Please check the $DISPLAY variable.");
+		}
 	}
 };