Re: Re: Self-descriptive messages

I think we need to separate the questions: "is this self-descriptive?" from "is this a good way to do shopping cart ordering?".

There's a very specific definition of self-descriptive (from a REST point-of-view) in Roy's thesis that this request passes. There are a whole bunch of other constraints that aren't part of REST that are needed for an e-commerce system that it almost certainly doesn't, including non-repudiation, transparency of intent, etc.

I'm *not* arguing you should build shopping carts this way; I'm just arguing it fits the very specific, technical definition of self-descriptive. REST isn't a magic wand--meeting its constraints doesn't guarantee you've built a suitable system.

Jon
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Jon Moore


On Aug 26, 2012, at 3:10 AM, "Bob" <[email protected]<mailto:[email protected]>> wrote:



I lost a long argument with Mark Baker a year and a half ago on this very subject and scenario.

I argued that including the URL to a saved offer-to-buy in a message to convert it into an order was adequately self-descriptive.

At the end of the discussion, I accepted Mark's position, and abandoned my own.

However, I thought of another reason that convinced me even more of the correctness of Mark's argument from a business standpoint, and that is non-repudiation: http://en.wikipedia.org/wiki/Non-repudiation

That is, if both parties to an electronic agreement send, receive and sign each of the full messages exchanged in the dialog, maybe even exchanging the whole built-up sequence each time, they have a record of the agreement that would be difficult for either party to repudiate.

This reason may not have been Roy's reason for including self-descriptive messages as a REST constraint, but it would be important in business contract situations.