[swift-server-dev] Prototype of the discussed HTTP API Spec

Paulo Faria paulo at zewo.io
Tue May 30 09:41:28 CDT 2017

oh.. scratch that.. the ordered dict won't help with proxying at all.. ouch.

On 30 May 2017 at 11:40, Paulo Faria <paulo at zewo.io> wrote:

> Hi, Johannes!
> You're right. It helps performance by not having to go through all the
> headers and lowercase then when they might not be needed during request
> handling. This worked well in my own code because I used a dictionary as a
> backing storage, having O(1) retrieval. Ideally the best backing storage
> would be:
> OrderedDictionary<Field, [String]>
> - This way we have a single source of truth (another problem with the two
> storages approach)
> - We don't have to do lowercase on all headers even if they're not needed
> later.
> - The case insensitive comparison from Field is done when the user
> actually needs the header.
> - We maintain the original order of the http message in cases of proxying.
> - Retrieval is done in O(1)
> Cheers,
> Paulo
> On 30 May 2017 at 11:29, Johannes Weiss <johannesweiss at apple.com> wrote:
>> Hi,
>> > On 27 May 2017, at 2:18 pm, Paulo Faria via swift-server-dev <
>> swift-server-dev at swift.org> wrote:
>> >
>> > Michael, I narrowed the scope of the proposal and focused the
>> rationale. I answered your comments about switch for HTTPMethod and
>> HTTPStatus. Basically, we can switch on them because I implemented the
>> pattern matching operator ~=. I also removed the HTTPMessage as it is not
>> *needed* and users can define it and make HTTPRequest and HTTPResponse
>> conform to it in extensions in their own module.
>> >
>> > https://github.com/paulofaria/http-api-proposal#rationale
>> >
>> > Carl, Helge, Chris and Rien what do you think about the code? This is
>> pretty close to what Carl suggested.
>> >
>> > The main differences are..
>> >
>> > HTTPVersion as a struct.
>> > HTTPHeaders backed by a single array storage and case insensitive
>> checking is done with the Field type to improve performance.
>> not opposed to having a 'Field', but how does that improve performance?
>> It reduces memory usage but having a single list makes the lookup of a
>> certain header field with .filter O(n) instead of O(1).
>> > HTTPMethod as a struct instead of enum with pattern matching added
>> allowing switch cases. (pointed by Helge)
>> > HTTPStatus as a struct instead of enum with pattern matching added
>> allowing switch cases. (pointed by Helge)
>> happy with those. Except the proposed hashing functions
>> return method.hashValue ^ uri.hashValue ^ version.hashValue ^
>> headers.hashValue
>> is really not appropriate but I guess it's more a proof of concept.
>> -- Johannes
>> > Apart from that there's only naming differences. I added some tests to
>> showcase what I mentioned.
>> >
>> > https://github.com/paulofaria/http-api-proposal/blob/master/
>> Tests/HTTPTests/HTTPTests.swift
>> >
>> > On 27 May 2017 at 08:41, Michael Chiu <hatsuneyuji at icloud.com> wrote:
>> > The thing is, as I have mentioned before if we move on that route we
>> have to have a well defined structure before hand, for example, there’s no
>> such protocol “Message” in what Johannes proposed.
>> >
>> > As Chris and Carl mentioned before, this is only a prototype of the
>> discussed API, so at least we have something to test, experiment and
>> branchmark on.
>> >
>> > Also things like WebApp in Johannes’ proposal can easily remove without
>> huge changes, since WebApp is simply a typealias. I really don’t think
>> that’s a big issue, every other parts of the prototype is in fact pretty
>> http-specific.
>> >
>> > Yes the prototype might dependent on some other frameworks like blue
>> socket, but that’s how we can at least test and branchmark.
>> >
>> > Sincerely
>> > Michael
>> >
>> >
>> >> On May 27, 2017, at 4:06 AM, Paulo Faria <paulo at zewo.io> wrote:
>> >>
>> >> Sorry if I'm being annoying, but I really feel what we lack is
>> process. There's no formal proposal and proposal review. I really think we
>> should move incrementally with well defined scopes and deadlines for every
>> round. We didn't have that so far. Carl and others said that my suggestion
>> is counter productive. I think the opposite, of course, as what I'm
>> proposing is a well defined process where when we settle on a design for a
>> particular set of base APIs then we move on to a higher absctraction. This
>> way we won't be discussing the same things over and over again. I'll
>> repeat, if we can't agree on the base types how can we move on? I'm saying
>> let's first *settle* on Version, Headers, Message, Request and Response.
>> Really *define* the API so then we move on, incrementally, from lower
>> abstraction to higher abstraction.
>> >>
>> >>
>> >>
>> >> On May 27, 2017 07:53, "Paulo Faria" <paulo at zewo.io> wrote:
>> >> I'm just proposing we move the code incrementally. The "most
>> consentual" list I sent yesterday isn't radically different from the code
>> Johannes proposed. I really don't want to discuss this over and over, ad
>> infinitum. The most important in the messages I sent before is that we need
>> a well defined process. We don't have it. Just taking the first
>> implementation, with a lot of things that admitedly don't fit the scope,
>> and adding that so we can rework doesn't feel right to me. I'm actually
>> confused about the scope this project is taking. The code there explicitly
>> mentions a WebApp, which is a higher responsibility than HTTP. When we
>> started this project the scope as very clear. Crypto/TLS, Socket, HTTP. A
>> well designed HTTP module shouldn't depend *at all* on the socket
>> implementation. Providing an implementation would be just a matter of
>> injecting a dependency. Moving that code as is to the org really doesn't
>> feel right to me. All I'm saying is that we definitely should start having
>> code on the org. But I say we move first Version, Headers, Message,
>> Request, Response. And again, the "least controversial" I sent yesterday
>> isn't radically strange. It's an evolution of Johaness original proposal,
>> plus Carl's, plus Helge's suggestions, plus my suggestions. The only thing
>> I added that wasn't discussed before is HTTPHeader.Field which does a case
>> insensitive comparison in its equatable implementation, and the Message
>> protocol which holds the properties common to request and response (version
>> and headers). If we can't agree on that, which is the sum of everything
>> that was discussed about these particular types. How can we agree on that
>> full implementation?
>> >>
>> >> On May 27, 2017 05:13, "Michael Chiu" <hatsuneyuji at icloud.com> wrote:
>> >> Hi Carl
>> >>
>> >>
>> >> >       This email thread isn’t about an API proposal. It’s about a
>> prototype implementation of an API that was already proposed and discussed
>> a month and a half ago.  The prototype isn't a full-featured framework like
>> Vapor or Kitura, but it does actually work and it even has XCTests with
>> decent (>75%) code coverage.
>> >>
>> >> I see, I was confused by the email contents instead of reading the
>> subject and thought we are finally implementing some code. TBH, I don’t see
>> any reason why this should not move to swift-server on github, It sounds a
>> good start to me.
>> >> Thank you guys’ hard work for building it.
>> >>
>> >> >       Also, please note that I didn’t play any part in proposing
>> this API back in March/April - it’s not “Carl’s proposal.”  I just took the
>> existing API that the group had previously discussed and implemented enough
>> of it so that we could measure the utility and performance of the API as
>> proposed and so that we could have better informed discussions about
>> potential alternatives.
>> >>
>> >> You’re right. it was Johannes’ proposal, I’m so sorry for that.
>> >>
>> >> Michael.
>> >>
>> >>
>> >
>> >
>> > _______________________________________________
>> > swift-server-dev mailing list
>> > swift-server-dev at swift.org
>> > https://lists.swift.org/mailman/listinfo/swift-server-dev
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