Comment 8 for bug 767205

I mildly prefer adding new methods to overloading using keyword arguments.

It's OK from our perspective to depend on a version of Twisted that has twisted.web.client.Agent (that would be Twisted >= 9.0, released in December 2009, and it would be alright for it for be a bit later than that if there were bugs / missing features in the 9.0 implementation of Agent).

It's not good to be restricted to one producer implementation. I don't understand why supporting arbitrary producers would require extending Query, though. Shouldn't the new put method be returning an IConsumer, so that the client can call registerProducer on it with its own choice of producer? (http://twistedmatrix.com/documents/11.0.0/core/howto/producers.html)

In our case (Tahoe-LAFS), the client doesn't know the Content-MD5 before it starts sending the data. Do you know if there is a way to tell S3 what the Content-MD5 should have been at the end of the transfer? (For Tahoe-LAFS this is not an integrity issue because we have other hashes protecting integrity, but it is a data preservation issue if we end up thinking that we've stored the data correctly on a particular server when we haven't.)