1. XML in CCSDS CCSDS Spring Meeting - Montreal
GMVSA 4081/04
Fran Martínez
2004/05/13

2. ODM to XML (XODM) conversion
Contents
Introduction to XML
Description
Pros and cons
XML tools
OrbitML
ODM to XML (XODM) conversion
Requirements and description
Tool architecture
Conclusions
Coming developments
Tracking
Attitude
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3. Introduction to XML
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4. eXtensible Mark-up Language Implementation
Introduction to XML
eXtensible Mark-up Language
Implementation
Tags : <name> … </name>
Attributes : <name attrib=“value”>
Used for data representation
Hierarchy
Structure
Qualification
No format
Definition and verification
DTD
Schema
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5. Hierarchy Introduction to XML Page 5 <stateVector>
<time> T00:00:00.000</time>
<position>
<X> </X>
<Y> </Y>
<Z> </Z>
</position>
<velocity>
<VX> </VX>
<VY> </VY>
<VZ> </VZ>
</velocity>
</stateVector>
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6. Structure Introduction to XML Page 6 <eventsFile>
<timeSpan>
<start> T09:30:47-05:00</start>
<end> T09:30:47-05:00</end>
</timeSpan>
<eventsRecord>
<time> T09:30:47-05:00</time>
<satelliteId>String</satelliteId>
<name>String</name>
<description>String</description>
</eventsRecord> …
</eventsFile>
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7. Qualification Introduction to XML Page 7
<stateVector frame="TOD”>
<time scale="UTC" format="calendar">
T00:00:00.000
</time>
<position units="km">
<X> </X>
<Y> </Y>
<Z> </Z>
</position>
<velocity units="km/s">
<VX> </VX>
<VY> </VY>
<VZ> </VZ>
</velocity>
</stateVector>
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8. No format Introduction to XML Page 8 X = 6655.9942 Y = -40218.5751
<stateVector>
<time> T00:00:00.000</time>
<position>
<X> </X>
<Y> </Y>
<Z> </Z>
</position>
<velocity>
<VX> </VX>
<VY> </VY>
<VZ> </VZ>
</velocity>
</stateVector>
X =
Y =
Z =
X_DOT =
Y_DOT =
Z_DOT =
<stateVector><time> T00:00:00.000</time><position><X> </X><Y> </Y><Z> </Z></position><velocity><VX> </VX><VY> </VY><VZ> </VZ></velocity></stateVector>
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9. Advantages Disadvantages Data structuring and organisation
Introduction to XML
Advantages
Data structuring and organisation
Extended in many fields
Generic tools
Innovative developments
Generalised validation mechanisms
Easy data transport with qualifiers
Object orientation
Disadvantages
Storage overhead
Not human readable format
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10. DTD Document structure Defines items and sequences
Introduction to XML
DTD
Document structure
Defines items and sequences
Validation of syntax only
<!ELEMENT stateVector (time, position, velocity)>
<!ATTLIST stateVector
frame CDATA #REQUIRED
>
<!ELEMENT time (#PCDATA)>
<!ATTLIST time
scale CDATA #REQUIRED
format CDATA #REQUIRED
comment CDATA #REQUIRED
<!ELEMENT position (X, Y, Z)>
<!ATTLIST position
units CDATA #REQUIRED
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11. Schema Defines document abstract structure Validation of semantics XML
Introduction to XML
Schema
Defines document abstract structure
Validation of semantics
XML
<xs:complexType name="stateVectorType">
<xs:sequence>
<xs:element name="time" type="dateTimeType"/>
<xs:element name="position" type="positionType"/>
<xs:element name="velocity" type="velocityType"/>
</xs:sequence>
<xs:attribute name="frame" type="frameType" use="optional" default="J2000"/>
</xs:complexType>
<xs:complexType name="positionType">
<xs:element name="X" type="lengthMagnitude"/>
<xs:element name="Y" type="lengthMagnitude"/>
<xs:element name="Z" type="lengthMagnitude"/>
<xs:attribute name="units" type="lengthUnits" use="optional" default="m"/>
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12. Parsing tools Visualisation tools Validation tools xerces
Introduction to XML
Parsing tools
xerces
DOM
SAX
Implementation in C++, Java, Tcl, …
Visualisation tools
Web navigators
CSS
XSLT
Validation tools
DTD
Schema
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13. OrbitML
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14. OrbitML Spacecraft Flight Dynamics Mark-up Language
Covers the whole s/c FD spectrum, including:
Orbit and attitude determination & prediction
Events generation
Geodetic Applications
Navigation
Handles related concepts
Satellites, transponders, ground stations, physical models, ...
Object (Data) oriented approach
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15. OrbitML is a rich source of FD metadata
Design drivers
Heritage from European FD packages …
… improved consistency and portability
Readability
Extensibility to other space applications
OrbitML is a rich source of FD metadata
Data model
hierarchy through XML
data typing through XML Schema …
… extended by OrbitML
Data relationship
basic by XML and Schema …
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16. ODM to XML Conversion Tool
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17. ODM to XML Conversion Tool
Requirements
ODM  XML notation
Analysis of ODM
Translation into XML (XODM)
XML structured data (data tree)
Investigation of conversion tool
Approach
Analysis of ODM data structures
Definition of the XML approach
Existing tools
Existing supporting elements (OrbitML)
Definition of the XODM structures
Prototype demonstration
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18. ODM to XML Conversion Tool
Tool generation rationale
Isolate memory structures from data format representations (ODM & XODM)
Perform validation of input files
Common mapping to memory for both file representations
Data structure sharing
Bi-directional reading/writing
Object oriented approach
XML/Schema  UML  C++
Low level items reuse
Tools for scanning and parsing
xerces-c/SAX for XODM
lex + yacc for ODM
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19. ODM to XML Conversion Tool
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20. ODM to XML Conversion Tool
OPM Data Structure
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21. ODM to XML Conversion Tool
OEM Data Structure
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22. ODM to XML Conversion Tool
ODM Parser
Architecture
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23. ODM to XML Conversion Tool
Xerces/SAX
Architecture
Example
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24. ODM to XML Conversion Tool
Tool generation conclusions
Easy translation of data elements to XML
Portable C++ (linux, windows, solaris)
Full definition through Schema
Proven reuse of OrbitML low level items
Schema
C++ data representation
XODM integrated in OrbitML
Difficulties
Format vs. Data structure
Insertion of comments (ambiguities)
ODM fixed units vs. XODM attributes
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25. Coming Developments
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26. CCSDS Approach Procedure To come next
Coming Developments
CCSDS Approach
For already analysed elements (ODM)
For items to be processed
Procedure
Same as for ODM (?)
Existing formats/structures
Newly defined structures (directly in XML)
Define procedure
Analysis
Definition of structures
Identification of reusable items
To come next
Tracking
Attitude
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27. Coming Developments Page 27 OrbitML observation file type structure
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28. Coming Developments Page 28 OrbitML attitude file type structure
2004/05/13