protocol OrderPayGoodsCancel {
	roles B, S
	parameters out ID key, out item, out price, out gDone, out pDone
	private rescind

	B -> S: order [out ID key, out item, out price]
	B -> S: cancel [in ID key, out rescind]
	B -> S: pay [in ID key, in price, nil rescind, out pDone]
	B -> S: cancelOrderConfirm [in ID key, in gDone, out pDone]

	S -> B: goods [in ID key, in item, nil rescind, out gDone]
	S -> B: CancelAck [in ID key, in rescind, out gDone]
}