DD 36, addressing Christian's review.

1 files changed, 14 insertions, 18 deletions

diff --git a/design-documents/036-currency-conversion-service.rst b/design-documents/036-currency-conversion-service.rst
index 7c9bbc72..be33c591 100644
--- a/design-documents/036-currency-conversion-service.rst
+++ b/design-documents/036-currency-conversion-service.rst
@@ -40,7 +40,7 @@ Requirements
   regional currency ('buy-in' operation).
 * CCS must offer cash-out operations.
 * CCS should react as soon as possible to buy-in and cash-out operations.
-* CCS must show its state to administrators.
+* CCS must show its state to administrators and offer management tools.
 * CCS must link every fiat-side of a cash-out to its regional currency
   counterpart.  In particular, because every cash-out starts with a
   payment *P* from regio-user to regio-issuer and ends with another
@@ -61,34 +61,30 @@ Sandbox performs a first wire transfer from regio-user to regio-issuer
 by specifying the amount without any rates/fees applied.  Along
 the same database transaction, Sandbox stores the *instructions*
 of another payment *P* from fiat-issuer to fiat-target, but this time
-**with** the cash-out rates/fees.
+**with** the cash-out rates/fees.  Notably, P includes the **current**
+fiat-target and the rates/fees, since these are configurable.
 
-Asynchronously, a background picks P and sends it to the fiat bank.
+Asynchronously, a background task picks P and sends it to the fiat bank.
 Finally, fiat bank conducts P and fiat-target receives the wanted
 amount.  The same background task should also retry previous payments
 like P that failed to be submitted to fiat bank.
 
+CCS offers management endpoints for prepared fiat-transactions.
+Through them, adminisrators can see, retry, or cancel every fiat-transaction
+that was prepared to pay fiat-target.
+
 Buy-in operation
 ----------------
 
 A buy-in operation starts as soon as the customer sends a fiat
 payment from fiat-customer to fiat-issuer.  Sandbox is responsible to
-detect such an incoming payment in a timely fashion.
-Because traditional banking protocols (like EBICS) don't allow to long
-poll on bank accounts, Sandbox uses background tasks to check fiat-issuer
-every X minutes.  Those background tasks rely on Nexus ability to speak
-EBICS.
+detect such an incoming payment in a timely fashion.  The detection
+happens by long polling on the Nexus JSON API.  Nexus is ultimately
+responsible to query the fiat bank via EBICS every X seconds.  X
+should match the tightest interval allowed by the bank.
 
 When Sandbox detects one incoming payment on fiat-issuer, it applies the
-buy-in rates/fees and wires the resuling amount from regio-issuer to
-regio-exchange.  At this point, Nexus detects the incoming payment on
+**current** buy-in rates/fees and wires the resuling amount from regio-issuer
+to regio-exchange.  At this point, Nexus detects the incoming payment on
 regio-exchange and makes the exchange aware via the Taler Wire Gateway API.
 From now on, the system proceeds like it always did in Taler.
-
-Background tasks
-================
-
-The background tasks are responsible for the communication between Sandbox
-and fiat bank, in order to drive fiat-issuer.  Their implementation requires
-to extract the current Nexus background tasks and EBICS logic into own
-libraries.