--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/tmatesoft/hg/internal/DataSerializer.java	Mon Feb 04 18:00:55 2013 +0100
@@ -0,0 +1,92 @@
+/*
+ * Copyright (c) 2013 TMate Software Ltd
+ *  
+ * 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 2 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.
+ *
+ * For information on how to redistribute this software under
+ * the terms of a license other than GNU General Public License
+ * contact TMate Software at support@hg4j.com
+ */
+package org.tmatesoft.hg.internal;
+
+import java.io.IOException;
+
+/**
+ * Serialization friend of {@link DataAccess}
+ * 
+ * @author Artem Tikhomirov
+ * @author TMate Software Ltd.
+ */
+@Experimental(reason="Work in progress")
+public class DataSerializer {
+	
+	public void writeByte(byte... values) throws IOException {
+		write(values, 0, values.length);
+	}
+
+	public void writeInt(int... values) throws IOException {
+		byte[] buf = new byte[4];
+		for (int v : values) {
+			bigEndian(v, buf, 0);
+			write(buf, 0, buf.length);
+		}
+	}
+
+	public void write(byte[] data, int offset, int length) throws IOException {
+		throw new IOException("Attempt to write to non-existent file");
+	}
+
+	public void done() {
+		// FIXME perhaps, shall allow IOException, too
+		// no-op
+	}
+	
+	/**
+	 * Writes 4 bytes of supplied value into the buffer at given offset, big-endian. 
+	 */
+	public static final void bigEndian(int value, byte[] buffer, int offset) {
+		assert offset + 4 <= buffer.length; 
+		buffer[offset++] = (byte) ((value >>> 24) & 0x0ff);
+		buffer[offset++] = (byte) ((value >>> 16) & 0x0ff);
+		buffer[offset++] = (byte) ((value >>> 8) & 0x0ff);
+		buffer[offset++] = (byte) (value & 0x0ff);
+	}
+	
+	@Experimental(reason="Work in progress")
+	interface DataSource {
+		public void serialize(DataSerializer out) throws IOException;
+
+		/**
+		 * Hint of data length it would like to writes
+		 * @return -1 if can't answer
+		 */
+		public int serializeLength();
+	}
+	
+	public static class ByteArrayDataSource implements DataSource {
+		
+		private final byte[] data;
+
+		public ByteArrayDataSource(byte[] bytes) {
+			data = bytes;
+		}
+
+		public void serialize(DataSerializer out) throws IOException {
+			if (data != null) {
+				out.write(data, 0, data.length);
+			}
+		}
+
+		public int serializeLength() {
+			return data == null ? 0 : data.length;
+		}
+		
+	}
+}