General Architecture

Minstrel shall support state-of-the-art electronic commerce as an initial design concept since not all content available via channels, e.g. stock exchange data, programs, etc., will be available free of charge. A set of payment profiles shall be supported: pay-per-view, volume-based, time-based, and flat fees.

Minstrel shall have a flexible payment interface that allows multiple payment profiles and payment protocols to co-exist. In its initial implementation Minstrel shall use micropayment for a pay-per-view strategy as a prototype testbed (without constraining other types).

Paying for channel information in Minstrel works as follows (the terminology is borrowed from Millicent by DEC):

Minstrel commerce (pay-per-view)

1. The broker buys larger amounts of Scrip from the push vendor.

2. The receiver buys some scrip from the broker.

The above steps are only performed once in a while.

3. User requests information.

4. MRCU sends request to the broadcaster (push vendor).

5. Push vendor sends a payment handle.

6. MRCU sends the payment handle to the receiver's wallet.

7. Receiver's wallet sends the payment handle and the required amount to the broadcaster's (vendor's) payment server.

8. Payment server acknowledges payment to receiver's wallet.

9. Payment server notifies push vendor that a certain payment identified by the payment handle was done.

10. Receiver's wallet notifies MRCU that payment has been done and acknowledged.

11. Push vendor sends the information that was paid for to the receiver (MRCU).

12. MRCU instructs the presentation unit to display the information.

Note: Steps 9 and 10 can be done concurrently.

Millicent Package

The first payment protocol that will be supported by Minstrel is Millicent. Millicent is a micropayment protocol developed by DEC. It is designed to support electronic commerce on the Internet. Millicent supports small purchases, e.g. pay for a WWW page, push channel, etc. Since it is intended for small amounts only (some cents to a few dollars) its security constraints and protocol are lightweight compared to other payment protocols. The Millicent package implements a Java component (JavaBean) which supports the Millicent protocol. Typical patterns for payment on the Internet (pay-per-view, flat fee, etc.) shall be supported.

1.	The broker buys larger amounts of Scrip from the push vendor.
2.	The receiver buys some scrip from the broker.
The above steps are only performed once in a while.
3.	User requests information.
4.	MRCU sends request to the broadcaster (push vendor).
5.	Push vendor sends a payment handle.
6.	MRCU sends the payment handle to the receiver's wallet.
7.	Receiver's wallet sends the payment handle and the required amount to the broadcaster's (vendor's) payment server.
8.	Payment server acknowledges payment to receiver's wallet.
9.	Payment server notifies push vendor that a certain payment identified by the payment handle was done.
10.	Receiver's wallet notifies MRCU that payment has been done and acknowledged.
11.	Push vendor sends the information that was paid for to the receiver (MRCU).
12.	MRCU instructs the presentation unit to display the information.
Note: Steps 9 and 10 can be done concurrently.