UTILIZATION OF FORWARD ERROR CORRECTION (FEC) TECHNIQUES WITH EXTENSIBLE MARKUP LANGUAGE (XML) SCHEMA-BASED BINARY COMPRESSION (XSBC) TECHNOLOGY LT Terry D. Norbraten, USN December 2004

THE MOVES INSTITUTE2 The Very Basics

THE MOVES INSTITUTE3 Formally known as Cross-format Schema Protocol (XFSP) in NPSNET-V Target Area XML Serialization / XML Marshalling Transactions via XML with reliability Possible Applications Networked Virtual Environments (NVEs) AUV Workbench Server / AUVs, UUVs, UAVs XML-based Tactical Chat (XTC) Benefits Schemas can be tailored: No need to hard code protocols Compact Efficient Platform-independent Run-time extensibility Built-in redundancy with minimal cycle overhead

THE MOVES INSTITUTE4 XSBC w/ FEC Idea : Creating DOM Pipe between users FEC Encoded XML Data Schema DOM : Document Object Model

THE MOVES INSTITUTE5 XSBC w/ FEC Data Flow XML Data Flow XML Schema Defining Mission Data Document Structure GZip/XSBC Serializer Module FEC Encoder (Optional) AUV Acoustic Modem XML Document (Mission Data) to transmit Acoustic Medium XML Document (Mission Data) stored from an AUV UnGZip/XSBC De-Serializer Module FEC Decoder XML Schema Defining Mission Data Document Structure AUV Workbench Server Acoustic Modem Acoustic Medium

THE MOVES INSTITUTE6 XSBC w/ FEC Process: XML Serialization and Encoding Parse the schema document Create a look-up table for attributes and elements Assign unique numbers to the elements and attributes Walk through the XML tree and put each element and attribute into the output stream by replacing their tag names with numbers Capture bit stream and encode with redundancy: an (n, k) code takes k original source symbols and encodes n-k redundant symbols, then sends all n via UDP packets

THE MOVES INSTITUTE7 XSBC w/ FEC <protocol xmlns:xsi=" instance" xsi:noNamespaceSchemaLocation="example.xsd"> 1 2

THE MOVES INSTITUTE8 XSBC w/ FEC 1 2

THE MOVES INSTITUTE9 FEC Overview

THE MOVES INSTITUTE10 XSBC w/ FEC Process: Decoding and XML De-serialization Receive any subset k of the n UDP repair packets sent to reconstruct original data Read tag numbers from decoded data symbols Retrieve element or attribute associated with that number Read the data Create the elements, attributes and bind data to them Rebuild the XML tree Store reconstructed file for later retrieval

THE MOVES INSTITUTE11 UDP Example of XML -> XSBC -> FEC and back

THE MOVES INSTITUTE12 FEC Principle of Operation Encoded data represented as: y = E x where x is a k-vector with source data, y is an n-vector with the redundant info and E is an n*k derived Vandermonde matrix. The code is systematic.

THE MOVES INSTITUTE13 FEC Principle of Operation At the receiver, any subset y’ of k elements from y allows the reconstruction of the whole x by solving the system: y’ = E’ x where E’ is made of rows from E corresponding to the received elements

THE MOVES INSTITUTE14 Systematic code data recovery

THE MOVES INSTITUTE15 ComparisonTool Autonomous Vehicle Mission Output XML file

THE MOVES INSTITUTE16 Teapot Exemplar