--- a/src/SerializeHandler.h	Sat Apr 16 22:19:37 2022 +0200
+++ b/src/SerializeHandler.h	Sun Apr 17 01:31:28 2022 +0200
@@ -18,6 +18,9 @@
 
 #include <regex>
 #include <stdexcept>
+#include <sstream>
+#include <codecvt>
+#include <iomanip>
 
 #include <relpipe/common/type/typedefs.h>
 #include <relpipe/reader/TypeId.h>
@@ -37,22 +40,78 @@
 class SerializeHandler : public relpipe::reader::handlers::RelationalReaderStringHandler {
 private:
 	Configuration configuration;
-	shared_ptr<relpipe::writer::RelationalWriter> relationalWriter;
+	shared_ptr<relpipe::writer::RelationalWriter> writer;
+	std::wstring_convert<codecvt_utf8<wchar_t>> convertor;
+
+	class RelationContext {
+	public:
+		relpipe::common::type::StringX name;
+		std::vector<relpipe::reader::handlers::AttributeMetadata> readerMetadata;
+		std::vector<relpipe::writer::AttributeMetadata> writerMetadata;
+	} relationContext;
+
+	class RecordContext {
+	public:
+		std::stringstream buffer;
+		shared_ptr<relpipe::writer::RelationalWriter> writer;
+		size_t attributeIndex = 0;
+	} recordContext;
+
+	relpipe::common::type::StringX toHex(const std::string& octets) {
+		std::stringstream hex;
+		hex << std::hex << std::setfill('0') << std::hex;
+		for (size_t i = 0, size = octets.size(); i < size; i++) hex << std::setw(2) << (0xff & octets[i]);
+		return convertor.from_bytes(hex.str());
+	}
+
 public:
 
-	SerializeHandler(shared_ptr<relpipe::writer::RelationalWriter> relationalWriter, Configuration configuration) : relationalWriter(relationalWriter), configuration(configuration) {
+	SerializeHandler(shared_ptr<relpipe::writer::RelationalWriter> writer, Configuration configuration) : writer(writer), configuration(configuration) {
+		// TODO: configurable relation name
+		// TODO: configurable attribute name
+		// TODO: optional custom attributes with constant value or ordinal number
+		// TODO: optional serialization of only certain relations? and certain fields?
+		// TODO: optional pass-through of certain relations?
+		// TODO: multiple modes? one output record per a) one input record, b) several input records, c) one input relation, … ?
+
+		writer->startRelation(L"message",{
+			{L"data", relpipe::writer::TypeId::STRING} // TODO: octet-string (when supported) instead of HEX
+		}, true);
 	}
 
 	virtual ~SerializeHandler() = default;
 
 	void startRelation(relpipe::common::type::StringX name, std::vector<relpipe::reader::handlers::AttributeMetadata> attributes) override {
+		relationContext = RelationContext();
+
+		relationContext.name = name;
+		relationContext.readerMetadata = attributes;
+
+		recordContext = RecordContext();
+		recordContext.writer.reset(relpipe::writer::Factory::create(recordContext.buffer));
+
+		for (relpipe::reader::handlers::AttributeMetadata readerMetadata : attributes) {
+			relationContext.writerMetadata.push_back({readerMetadata.getAttributeName(), writer->toTypeId(readerMetadata.getTypeName())});
+		}
 	}
 
 	void attribute(const relpipe::common::type::StringX& value) override {
+		if (recordContext.attributeIndex == 0) {
+			recordContext.writer->startRelation(relationContext.name, relationContext.writerMetadata, true);
+		}
 
+		recordContext.writer->writeAttribute(value); // TODO: typed values instead of strings
+		recordContext.attributeIndex++;
+
+		if (recordContext.attributeIndex % relationContext.readerMetadata.size() == 0) {
+			writer->writeAttribute(toHex(recordContext.buffer.str()));
+			recordContext = RecordContext();
+			recordContext.writer.reset(relpipe::writer::Factory::create(recordContext.buffer));
+		}
 	}
 
 	void endOfPipe() {
+		// TODO: check number of attribute values
 	}
 
 };