Design (Code) ~ Attempt 1

Attempt 1 at designing

The idea is to start from a first design, see advantages/issues, and improve on it with next iteration

Starting from Laurent's class design, one would get:

• RuleManager

  • Description: Rule manager manage a list of rules both for compression/decompression and Fragmentation/Reassembly
  • addRule(rule): Take a JSON rule and store it
  • findRuleFromID(id): return the JSON structure corresponding to the ID
  • findRuleFromHeader(HdR): return ruleID corresponding to an header description
  • findRuleFromFrag(mode, length): return fragmentation ruleID from characteristics (mode: no reliable, reliable) packet size

• Parser

  • Description: take a binary structure and return a list of field.name and values (should contain a field descriptions)
  • parser(packet, direction): direction can be "up" or "down"

• Compressor

  • Description: apply compression rules, return compression residue
  • apply(header_description, ruleID, direction)
  • CA: CA_not_sent, CA_value_sent, CA_matching_sent, CA_LSB

• Decompressor

  • Description: construct original header from residue and ruleID
  • apply(residue, ruleID, direction)
  • DA: DA_not_sent, DA_value_sent, DA_matching_sent, DA_LSB

• Fragmentation

  • Description: cut a buffer of bits regarding a ruleID and run teh state machine for the specific fragmentation behavior. Must specify tiles side
  • apply(bitbuffer, ruleID)

• Defragmentation

  • Description: state machine that regroups several fragments to form a SCHC packet

• Packet Sniffer, Packet Sender, Orchestrator, LPWAN send, LPWAN receive, bitbuffer, ... : TBD

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The sequence diagram for this design will correspond to what follows.

• Configuration is ignored
• SCHC corresponds to an orchestrator

(best viewed at 3840x2160 on 43")

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Analysis and possible improvements

• One important missing part are the classes related to the Layer2, and the interaction with Layer2:

  • Layer2 packet size
  • Possible explicit feedback on lost packets (transmissions opportunities, e.g. LoRa ??)
  • Q: should one use object composition for Layer2, or inheritance (e.g. http.server subclass of socketserver.TCPServer in Python) ?

• ...