The current spec is ambiguous in the case of what to do if the invoice contains one output of a fixed amount and one or more outputs of an unspecified amount. Should the user be prompted once per output? That seems suboptimal. Prompted once for a value that's then randomly distributed between all open-value outputs? It seems this ability of the protocol is somewhat more complex than it appears. The ability to have open outputs is nice for tips though.
You could consider moving pki_type and pki_data into a separate message and making both fields required, then making the pki message optional. Otherwise you can have pki_type set but no data or vice-versa. It doesn't make much difference in the end, just slightly improves the automatic sanity checks produced by the proto compiler. w.r.t SIGHASH_ANYONECANPAY. I think it's best not to use this routinely as it relaxes the signature checks in ways that may open non-obvious holes when combined with other features. I thought we pretty much had consensus on recursively calculating fees including dependents in the memory pool? Peter is correct that there are a few degrees of freedom in protobuf serialization, though far fewer than with JSON. I'd like to think upstream would be open to resolving these ambiguities. Re-serialization of an Invoice message in the Payment message is a potential source of mistakes. There's no need to ever concatenate these messages and alternative implementations that don't order serialized fields by tag number are missing an important optimization, so they could be fixed. The main issue is treatment of unknown fields. If/when the Invoice message is extended with other fields that are round-tripped through an old client, the data may get lost. JSON doesn't help resolve that either, of course. There are a few solutions: 1) Change the type of the Invoice field in Payment to be "bytes" and set it to be the hash of the originally received binary Invoice message. Downside, requires merchants to track all outstanding invoices. 2) Ask protobufs upstream to modify the spec/implementations so ordering of unknown fields is specified. The Python implementation could be extended to support them so Python implementors don't end up with accidental message downgrades. 3) Language of the spec could be changed to explicitly state that the received Invoice may not be binary-identical to the one that was sent, in the case of a client that incorrectly downgrades the message. Thus you'd be expected to check what the Invoice was using merchant_data which is opaque and could just be, eg, a database key on your own end. 4) Instead of submitting the entire Invoice back to the merchant, just the merchant_data could be in the Payment message. Of the four options I prefer the last. What is the use case for resubmitting the entire invoice anyway? Even if protobufs are improved so handling of round-tripping new messages through old [Python] clients is more rigorous, some implementors will probably convert the protobuf objects into some internal forms for whatever reason (or serialize them to a database, etc) and they're very likely to mess up the handling of unknown fields when they do it. ------------------------------------------------------------------------------ Keep yourself connected to Go Parallel: INSIGHTS What's next for parallel hardware, programming and related areas? Interviews and blogs by thought leaders keep you ahead of the curve. http://goparallel.sourceforge.net _______________________________________________ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
