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Re: [apps-discuss] content inspection in absence of media type, was: APPSDIR review of draft-ietf-httpbis-p2-semantics-24

2013-10-30 23:33:57
On 2013/10/30 18:47, Julian Reschke wrote:
On 2013-10-30 09:51, "Martin J. Dürst" wrote:
I have to say that I don't consider this sentence to be useless.

As far as I remember, there are other specs (mail?) that say that
text/plain is the default. So some implementers may be used to this, and
apply it to http, too.

Also, while every natural language text has to assume that the reader
uses a certain amount of rational thinking, specs are usually written
with a somewhat reduced expectation in that respect, not because the
average reader is particularly dumb, but because the consequences of
interpreting something wrong are different than the consequences of
getting something wrong when e.g. reading a novel.

So I don't see any reason for not keeping that sentence. Even if it
doesn't help, it definitely doesn't hurt.

So what exactly does it mean in *practice* to treat something as
"arbitrary data". What do you expect a browser to do in that case?

Let's say ask the user. That's what they are doing currently, as far as I'm aware of. I haven't checked every latest version of every browser, but on average, I'd expect a dialog that asks whether (and then where) I want to save the file, or with what application I want to open it.

But of course HTTP cannot say that, because HTTP is about more than browsers. But then, HTTP doesn't say what to do with data that is marked as application/octet-stream, the same way as it doesn't say what to do with data that is marked as text/html or any other media type. And that seems just fine.

Put another way, the sentence is not useless because clients already have to figure out what to do with data marked as application/octet stream. We just tell them to reuse and leverage what they have figured out and apply it to unlabeled content. If a client implementer, e.g. for a debugging tool, has figured out that they want to show application/octet-stream as plain text assuming a 'charset' that shows each byte separately, then it's fine for them to use that for unlabeled data.

That also means that the requirement is testable. Just check whether the same happens for data labeled as application/octet-stream and for unlabeled data. It may be difficult to automate such a test, in particular in a test suite that is supposed to work across clients, but it's nevertheless testable.

Also, the sentence is not useless because it tells implementers to NOT treat as any of the other available content types, and that's what's important.

Regards,   Martin.

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