--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/SubProcess.h	Sat Jan 11 00:56:51 2020 +0100
@@ -0,0 +1,84 @@
+/**
+ * Relational pipes
+ * Copyright © 2020 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/>.
+ */
+#pragma once
+
+#include <vector>
+#include <map>
+#include <string>
+#include <sstream>
+
+#include <relpipe/writer/typedefs.h>
+#include <relpipe/writer/RelpipeWriterException.h>
+
+/**
+ * TODO: move to a separate library → can be used later also in relpipe-tr-exec
+ */
+class SubProcess {
+public:
+
+	class Message {
+	public:
+		int code;
+		std::vector<relpipe::writer::string_t> parameters;
+
+		Message() {
+		}
+
+		Message(int code) : code(code) {
+		}
+
+		Message(int code, std::vector<relpipe::writer::string_t> parameters) : code(code), parameters(parameters) {
+		}
+
+		Message(int code, relpipe::writer::string_t p1) : code(code), parameters({p1}) {
+		}
+
+		Message(int code, relpipe::writer::string_t p1, relpipe::writer::string_t p2) : code(code), parameters({p1, p2}) {
+		}
+
+		Message(int code, relpipe::writer::string_t p1, relpipe::writer::string_t p2, relpipe::writer::string_t p3) : code(code), parameters({p1, p2, p3}) {
+		}
+
+		relpipe::writer::string_t toString() {
+			std::wstringstream s;
+			s << L"Message(code: " << code << L", parameters: ";
+			for (int i = 0; i < parameters.size(); i++) {
+				if (i < parameters.size() - 1) s << parameters[i] << L",";
+				else s << parameters[i];
+			}
+			s << L")";
+			return s.str();
+		}
+	};
+
+	class Exception : public relpipe::writer::RelpipeWriterException {
+	public:
+
+		Exception(std::wstring message) : relpipe::writer::RelpipeWriterException(message) {
+		}
+
+	};
+
+	static SubProcess* create(std::vector<relpipe::writer::string_t> commandLine, std::map<relpipe::writer::string_t, relpipe::writer::string_t> environment, bool dropErrorOutput = true);
+
+	virtual Message read() = 0;
+	virtual void write(Message message) = 0;
+	virtual int wait() = 0;
+
+	virtual ~SubProcess() = default;
+
+};