diff -r 98b901d7bb95 -r bef6648e79b1 include/relpipe/writer/RelationalWriter.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/include/relpipe/writer/RelationalWriter.h	Mon Aug 13 20:30:55 2018 +0200
@@ -0,0 +1,63 @@
+#pragma once
+
+#include <string>
+#include <iostream>
+#include <vector>
+
+#include "typedefs.h"
+#include "TypeId.h"
+
+namespace relpipe {
+namespace writer {
+
+class RelationalWriter {
+public:
+
+	virtual ~RelationalWriter() = default;
+
+	/**
+	 * @param typeCode string type code as defined in Specification
+	 * @return numeric id of given type
+	 * @throws RelpipeWriterException on unsupported typeCode
+	 */
+	virtual TypeId toTypeId(const string_t typeCode) = 0;
+
+	/**
+	 * @param typeId numeric type id as defined in Specification
+	 * @return string code of given type
+	 * @throws RelpipeWriterException on unsupported typeId
+	 */
+	virtual string_t toTypeCode(const TypeId typeId) = 0;
+
+	/**
+	 * @param name name of the relation (table)
+	 * @param attributes list of attributes (columns) containing their names and types
+	 * @param writeHeader header might be omitted – when appending new records to a stream alreaready containing the header
+	 */
+	virtual void startRelation(string_t name, std::vector<std::pair<string_t, TypeId>> attributes, boolean_t writeHeader) = 0;
+
+	/**
+	 * Writes a single attribute.
+	 * @param value string representation of value of given attribute type as defined in Specification
+	 */
+	virtual void writeAttribute(const string_t& value) = 0;
+
+	// TODO: fluent interface?
+	// TODO: << operator?
+	// TODO: write bitmap + attribute:
+	// virtual void writeBitmap(...) = 0;
+	// virtual void writeAttribute(string_t attribute) = 0;
+
+	/**
+	 * Writes a single attribute.
+	 * @param value raw pointer to the value in format of given attribute type as defined in Specification
+	 * @param type used as a safety mechanism to avoid wrong pointer interpretation;
+	 * should be called in this way: writeAttribute(&value, typeid(value));
+	 * if the type does not match, the RelpipeWriterException is thrown
+	 */
+	virtual void writeAttribute(const void* value, const std::type_info& type) = 0;
+
+};
+
+}
+}