Fix #60

Basic policy

• Make a module of echo.rs in interledger-service-util crate
• Insert the service into node.rs

Must-learn Specs

• ilp-prepare.ts
• echo.ts

ILP Packet handling in ilp-connector

• index.ts
  • creates App and listen
• app.ts
  • createApp loads accounts from env or config, and adds it to Accounts
  • listen
    • adminApi.listen()
    • backend.connect()
    • middlewareManager.setup()
    • accounts.loadIlpAddress()
    • accounts.connect()
    • middlewareManager.startup()
• middleware-manager.ts

memo

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