XML Telemetric

1
XML Telemetric Command Exchange Documentation
Magenta Book 2Kevin Rice NASA/GSFC(Jennifer
Muller ex-ESA)2008
2
Whats Wrong w/XTCE Magenta Book 1.2?

• Roughly split into two main sections
• Section X mainly about CCSDS usage
• Section Y mainly describes XTCE semantics
• Problems
• Sections have overlapping content
• Some examples show what not to do, not what to
  do
• Document is extremely long
• Some content is contradictory, written at
  different times by different people, thats not
  been aligned
• Solution
• Split XTCE 1.1 into TWO Magenta Books
• XTCE Core Semantics of XTCE
• XTCE CCSDS XTCE Best Practices for CCSDS Usage

3
Why We Need Magenta Books 1

• XTCE Semantics are not completely explained
  anywhere
• XTCE annotation is the first line for
  understanding XTCE (XTCE element names may
  provide some insight too)
• XTCE Tutorial is the second line for
  understanding XTCE semantics but it doesnt cover
  everything
• XTCE examples, additional explanatory material
  that you may have read forms a third line
• Solution
• XTCE Magenta Book Core captured all XTCE
  semantics in one place!
• (feed back to XTCE annotation for future version
  of Schema)

4
Why We Need Magenta Books 2

• XTCE Usage by Missions means decisions
• There are two overall ways to define Packets in
  XTCE Messages or Inheritance, which one?
• If you use Inheritance how many levels of
  inheritance will you support to build your
  packets?
• There are a variety of parameter types (data
  types) each with four possible link-encoding data
  types, which combinations will you use?
• Which calibrators will you support?
• Which alarms types will you support?
• Which XTCE elements will you use which will you
  avoid?
• Solution
• XTCE Magenta Book CCSDS show consistent way to
  define CCSDS Packet thru the header secondary
  header using XTCE
• List out decision areas and make suggestions on
  the various decision pts needed for YOUR mission
  after the header

5
XTCE Magenta Book Core

• Generate XTCE in annotation in tabular format
  using Apache XS Package to parse XTCE Schema
  directly
• (com.sun.org.apache.xerces.internal.x
  s.)
• Use Table to add new annotation describing all
  XTCE element and attributes
• Feed new annotation back to standard
• Provide additional sections to describe aspects
  of XTCE that may need more explanation
• Container Inheritance
• MetaCommand Inheritance
• Parameter/ArgumentType Inheritance
• Container EntryList addressing (LocationInContaine
  r) in conjunction with Inheritance and
  IncludeCondition
• NameReferences
• Other
• Status Table generated, put into CCSDS Document
  format, sections added LITTLE NEW CONTENT YET
  but some retrievable from OLD MB 1.2

6
XTCE Magenta Book Core

• SHOW MB CORE

7
XTCE Magenta Book CCSDS

• Re-focus on the CCSDS Packet the end users
  application data
• Ignore Frame sync, Reed Solomon, CADU, VCDU,
  M/B_PDU descriptions
• XTCE doesnt describe this fully enough
• And for MOST people this stuff is regulated to
  the FEP and invisible to them
• Show ONE way to define a CCSDS Header in XTCE
• Use official FIELD names in Parameters
• Show ONE way to define CCSDS Time fields in
  secondary header
• CCSDS Segmented and Unsegmented time formats
• Show ONE way to define individual packet using
  inheritance mechanism
• Extend individual packet containers from CCSDS
  Header Container
• Show ONE way to define Commands
• Use one MetaCommand per Command, extend
  MetaCommand/CommandContainer from CCSDS Header
  Container (similar to TLM side)
• Or have generic metaCommand as well ? (another
  layer of inheritance)
• Continue

8
XTCE Magenta Book CCSDS

• Re-focus on the CCSDS Packet the end users
  application data
• Ignore Frame sync, Reed Solomon, CADU, VCDU,
  M/B_PDU descriptions
• XTCE doesnt describe this fully enough
• And for MOST people this stuff is regulated to
  the FEP and invisible to them
• Show ONE way to define a CCSDS Header in XTCE
• Use official FIELD names in Parameters
• Show ONE way to define CCSDS Time fields in
  secondary header
• CCSDS Segmented and Unsegmented time formats
• Show ONE way to define individual packet using
  inheritance mechanism
• Extend individual packet containers from CCSDS
  Header Container
• Show ONE way to define Commands
• Use one MetaCommand per Command, extend
  MetaCommand/CommandContainer from CCSDS Header
  Container (similar to TLM side)
• Or have generic metaCommand as well ? (another
  layer of inheritance)
• Continue

9
XTCE Magenta Book CCSDS (more)

• Provide additional Sections on Packet Body
  after the header
• This is an area your mission will need to make
  some decisions before proceeding
• Provide ParameterType and Encoding Table
• Show XTCE ParameterTypes and likely encodings
  that make sense for them
• Provide ArgumentType and Encoding Table (similar
  to above)
• Discuss use of Contexts
• Discuss how to mimic Alarm Sets and Limits Sets
  with Contexts
• Discuss relationship between Parameter and
  ParameterType naming
• One parameter per parameter type?
• Discuss known ways to extend XTCE when what you
  need to describe is just not there
• Provide Template for Your Mission XTCE Required
  Practices document
• Basically the above sections form a sort of
  template for your mission to follow
• Status CCSDS Document format basic TOC. No
  new content generated (yet) but previously
  developed content available from a several
  sources
• SHOW MB CCSDS

10
XTCE Magenta Books 2 Conclusion

• Split XTCE MB into two MBs
• a Core which contains XTCE semantics only
• and CCSDS which has XTCE usage for CCSDS
  missions
• Use XTCE Core to feedback to standard
• For XTCE CCSDS focus on header, secondary header
  and time types and common naming.
• Then focus on the packet body which requires that
  your mission make some XTCE usage decisions
• Attempt to capture such decisions in a sort
  template which can be used by your mission in
  capturing a My Mission XTCE Required Practices
  document
• Comments.?