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XSC-0003: Streaming Token ​

XSC-0003 extends the XSC-0001 fungible-token interface with time-based payment streams. A conforming contract keeps balances, allowances, and streams in the same token contract.

Required Token Surface ​

An XSC-0003 token preserves the XSC-0001 functions:

  • change_metadata(key, value)
  • transfer(amount, to)
  • approve(amount, to)
  • transfer_from(amount, to, main_account)
  • balance_of(address)

It also exposes:

text
create_stream(receiver, rate, begins, closes)
balance_stream(stream_id)
change_close_time(stream_id, new_close_time)
finalize_stream(stream_id)
close_balance_finalize(stream_id)
balance_finalize(stream_id)
forfeit_stream(stream_id)

Stream Model ​

Each stream records its sender, receiver, start and close times, payment rate, claimed amount, and status. The stream identifier is derived deterministically from the stream parameters.

Accrual is lazy: the contract calculates and transfers the amount due when a stream function runs in a later block. Nothing executes between blocks.

Events ​

In addition to XSC-0001 Transfer and Approve events, the reference contract emits:

  • StreamCreated
  • StreamBalance
  • StreamCloseChange
  • StreamForfeit
  • StreamFinalized

Compatibility Notes ​

  • Keep function and argument names stable.
  • Parse begins, closes, and close-time updates as YYYY-MM-DD HH:MM:SS, and base accrual on finalized block time.
  • XSC-0003 does not define permit signatures. Pair it with XSC-0002 when signature-based approvals are needed.
  • The maintained reference implementation is xian-xips/XSC003_streaming_token.

The separate con_stream_payments package streams arbitrary external tokens through escrow. It is an application contract, not the XSC-0003 token interface. See Streaming Payments.