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# Price Authority

PriceAuthority is an object that mints PriceQuotes and handles triggers and notifiers for changes in the price.

PriceAuthority objects use timer services. You should be familiar with the objects and methods in the REPL TimerService document

# Price quote objects

Before discussing PriceAuthority and PriceAuthorityAdmin methods, we need to cover the other price-based objects and methods they interact with.

A PriceQuote is an object with two properties:

  • quoteAmount: An Amount whose value is a PriceQuoteValue.
  • quotePayment: The quoteAmount wrapped as a Payment. It is either an ERef<Payment> or null.

The quoteAmount describes a price available at a particular time. So that price can be shared by recipients with others, its associated quotePayment is the same value wrapped as a payment from the QuoteIssuer. This lets other recipients validate the quote is from the intended source.

Accessing the quotePayment value requires a round trip, so quoteAmountis included for the original recipient's convenience. They know who they received it from and don't need to validate provenance.

A PriceQuoteValue is the Value part of a quoteAmount. Its properties are:

  • amountIn { Amount }: The amount supplied to a trade
  • amountOut { Amount }: The quoted result of trading amountIn
  • timer { TimerService }: The service that gave the timestamp
  • timestamp { Timestamp }: A timestamp according to timer for the quote
  • conditions { any= }: Additional conditions for the quote

# getQuoteIssuer(brandIn, brandOut)

  • brandIn { Brand }
  • brandOut { Brand }
  • Returns: { ERef<Issuer> }

Returns the ERTP PriceQuote issuer for the specified brands pair.

# getTimerService(brandIn, brandOut)

  • brandIn { Brand }
  • brandOut { Brand }
  • Returns: { ERef<TimerService> }

Returns the timer used in PriceQuotes for the specified brands.

# makeQuoteNotifier(amountIn, brandOut)

  • amountIn { Amount }
  • brandOut { Brand }
  • Returns: { ERef<Notifier<PriceQuotes>> }

Be notified of the latest PriceQuotes for the given amountIn. Different PriceAuthories may issue these at very different rates.

# getPriceNotifier(brandIn, brandOut)

  • brandIn { Brand }
  • brandOut { Brand }
  • Returns: { Notifier }

Returns a notifier for the specified brands. Different PriceAuthories may issue these at very different rates.

# quoteGiven(amountIn, brandOut)

  • amountIn { Amount }
  • brandOut { Brand }
  • Returns: { Promise<PriceQuote> }

Returns a price quote corresponding to the specified amount in the specified brand. quoteGiven() essentially asks "how muchbrandOutwould I get foramountIn`.

Note that quoteGiven() and quoteWanted() can give different answers for not-trivial amounts.

# quoteWanted(brandIn, amountOut)

  • brandIn { Brand }
  • amountOut { Amount }
  • Returns: { Promise<PriceQuote> }

Returns a price quote for the specified amount in the specified brand. quoteWanted() essentially asks "how muchbrandInwould I have to pay to getamountOut`.

Note that quoteGiven() and quoteWanted() can give different answers for not-trivial amounts.

# quoteAtTime(deadline, amountIn, brandOut)

  • deadline { Timestamp }
  • amountIn { Amount }
  • brandOut { Brand }
  • Returns: { Promise<PriceQuote> }

Resolves after deadline passes on the Price Authority's timerService with amountIn's price quote at that time.

# quoteWhenGT(amountIn, amountOutLimit)

  • amountIn { Amount }
  • amountOutLimit{ Amount }`
  • Returns: { Promise<PriceQuote> }

Resolve when a price quote of amountIn exceeds amountOutLimit

# quoteWhenGTE(amountIn, amountOutLimit)

  • amountIn { Amount }
  • amountOutLimit{ Amount }`
  • Returns: { Promise<PriceQuote> }

Resolve when a price quote of amountIn reaches or exceeds amountOutLimit

# quoteWhenLTE(amountIn, amountOutLimit)

  • amountIn { Amount }
  • amountOutLimit{ Amount }`
  • Returns: { Promise<PriceQuote> }

Resolve when a price quote of amountIn reaches or drops below amountOutLimit

# quoteWhenLT(amountIn, amountOutLimit)

  • amountIn { Amount }
  • amountOutLimit{ Amount }`
  • Returns: { Promise<PriceQuote> }

Resolve when a price quote of amountIn drops to below amountOutLimit.