Interaction with bank websites

This section describes how bank websites can interact with the Taler wallet.

Currently the following functionality is supported:
  • Querying for the presence of a Taler wallet.
  • Receiving change notifications from the Taler wallet.
  • Creating a reserve.

For JavaScript code examples, see Communication Example.

Reserve Creation Request

The bank website can request the creation of a reserve. This operation will require the user to specify the exchange where he wants to create the reserve and the resolution of a CAPTCHA, before any action will be taken.

As a result of the reserve creation request, the following steps will happen in sequence:
  1. The user chooses the desired amount from the bank’s form
  2. Upon confirmation, the wallet fetches the desired amount from the user-filled form and prompts the user for the exchange base URL. Then ask the user to confirm creating the reserve.
  3. The wallet will create a key pair for the reserve.
  4. The wallet will request the CAPTCHA page to the bank. In that request’s parameters it communicates the desired amount, the reserve’s public key and the exchange base URL to the bank
  5. Upon successful resolution of the CAPTCHA by the user, the bank initiates the reserve creation according to the gotten parameters. Together with 200 OK status code sent back to the wallet, it gets also a ReserveCreated object.

Note that the reserve creation can be done by a SEPA wire transfer or some other means, depending on the user’s bank and chosen exchange.

In response to the reserve creation request, the Taler wallet MAY cause the current document location to be changed, in order to navigate to a wallet-internal confirmation page.

The bank requests reserve creation with the taler-create-reserve event. The event data must be a CreateReserveDetail:

interface CreateReserveDetail {

  // JSON 'amount' object. The amount the caller wants to transfer
  // to the recipient's count
  amount: Amount;

  // CAPTCHA's page URL which needs the following parameters
  // query parameters:
  // amount_value
  // amount_fraction
  // amount_currency
  // reserve_pub
  // exchange
  // wire_details (URL encoding of /wire output from the exchange)
  callback_url: string;

  // list of wire transfer types supported by the bank
  // e.g. "SEPA", "TEST"
  wt_types: Array<string>
interface ReserveCreated {

  // A URL informing the user about the succesfull outcome
  // of his operation
  redirect_url: string;