[swift-server-dev] HTTP API Sketch v2
Helge Heß
me at helgehess.eu
Thu Apr 6 03:07:08 CDT 2017
My understanding is that anything middleware is not a goal at all, except for permitting a middleware framework to be built on top of this.
This is just the low level http output stream, is there anything which you think prohibits building that on top?
The writer can be passed around, it is a ref object until done is called?
hh
On 6. Apr 2017, at 02:20, Colin Barrett via swift-server-dev <swift-server-dev at swift.org <mailto:swift-server-dev at swift.org>> wrote:
> Hello all,
>
> Is writing compositional middleware a goal for this iteration of the API? I noticed that the HTTPResponseWriter doesn't appear to allow for, e.g. writing a single header and then passing the writer on (as one would do in, say, an anti-CSRF middleware). Possible I'm missing something though!
>
> -Colin
>
> On Wed, Apr 5, 2017 at 1:36 PM Johannes Weiß via swift-server-dev <swift-server-dev at swift.org <mailto:swift-server-dev at swift.org>> wrote:
> Hi,
>
> First of all, thanks very much to Helge for carefully analysing (and implementing) the first API sketch. As promised, I reworked it a bit.
>
> Changes:
> - extracted HTTPResponse as its own value type (so it could also be used for a client)
> - added Helge's suggestions:
> * proper backpressure support
> * being able to ignore further parts of the HTTP body (stop parameter)
>
> If I forgot something important, please let me know. I can't promise that I'll address it before the meeting as I'm in another office tomorrow for meetings and probably won't be able to attend either.
>
> Please find everything below...
>
> Cheers,
> Johannes
>
> --- SNIP ---
> /* a web app is a function that gets a HTTPRequest and a HTTPResponseWriter and returns a function which processes the HTTP request body in chunks as they arrive */
>
> public typealias WebApp = (HTTPRequest, HTTPResponseWriter) -> HTTPBodyProcessing
>
> public struct HTTPRequest {
> public var method : HTTPMethod
> public var target : String /* e.g. "/foo/bar?buz=qux" */
> public var httpVersion : HTTPVersion
> public var headers : HTTPHeaders
> }
>
> public struct HTTPResponse {
> public var httpVersion : HTTPVersion
> public var status: HTTPResponseStatus
> public var transferEncoding: HTTPTransferEncoding
> public var headers: HTTPHeaders
> }
>
> public protocol HTTPResponseWriter: class {
> func writeContinue(headers: HTTPHeaders = HTTPHeaders()) /* to send an HTTP `100 Continue` */
>
> func writeResponse(_ response: HTTPResponse)
>
> func writeTrailer(key: String, value: String)
>
> func writeBody(data: DispatchData) /* convenience */
> func writeBody(data: Data) /* convenience */
> func writeBody(data: DispatchData, completion: @escaping (Result<POSIXError, ()>) -> Void)
> func writeBody(data: Data, completion: @escaping (Result<POSIXError, ()>) -> Void)
>
> func done() /* convenience */
> func done(completion: @escaping (Result<POSIXError, ()>) -> Void)
> func abort()
> }
>
> public typealias HTTPBodyHandler = (HTTPBodyChunk, inout Bool) -> Void /* the Bool can be set to true when we don't want to process anything further */
>
> public enum HTTPBodyProcessing {
> case discardBody /* if you're not interested in the body */
> case processBody(handler: HTTPBodyHandler)
> }
>
> public enum HTTPBodyChunk {
> case chunk(data: DispatchData, finishedProcessing: () -> Void) /* a new bit of the HTTP request body has arrived, finishedProcessing() must be called when done with that chunk */
> case failed(error: HTTPParserError) /* error while streaming the HTTP request body, eg. connection closed */
> case trailer(key: String, value: String) /* trailer has arrived (this we actually haven't implemented yet) */
> case end /* body and trailers finished */
> }
>
> public struct HTTPHeaders {
> var storage: [String:[String]] /* lower cased keys */
> var original: [(String, String)] /* original casing */
> var description: String
>
> subscript(key: String) -> [String]
> func makeIterator() -> IndexingIterator<Array<(String, String)>>
>
> init(_ headers: [(String, String)] = [])
> }
>
> public typealias HTTPVersion = (Int, Int)
>
> public enum HTTPTransferEncoding {
> case identity(contentLength: UInt)
> case chunked
> }
>
> public enum HTTPResponseStatus {
> /* use custom if you want to use a non-standard response code or
> have it available in a (UInt, String) pair from a higher-level web framework. */
> case custom(code: UInt, reasonPhrase: String)
>
> /* all the codes from http://www.iana.org/assignments/http-status-codes <http://www.iana.org/assignments/http-status-codes> */
> case `continue`
> case switchingProtocols
> case processing
> case ok
> case created
> case accepted
> case nonAuthoritativeInformation
> case noContent
> case resetContent
> case partialContent
> case multiStatus
> case alreadyReported
> case imUsed
> case multipleChoices
> case movedPermanently
> case found
> case seeOther
> case notModified
> case useProxy
> case temporaryRedirect
> case permanentRedirect
> case badRequest
> case unauthorized
> case paymentRequired
> case forbidden
> case notFound
> case methodNotAllowed
> case notAcceptable
> case proxyAuthenticationRequired
> case requestTimeout
> case conflict
> case gone
> case lengthRequired
> case preconditionFailed
> case payloadTooLarge
> case uriTooLong
> case unsupportedMediaType
> case rangeNotSatisfiable
> case expectationFailed
> case misdirectedRequest
> case unprocessableEntity
> case locked
> case failedDependency
> case upgradeRequired
> case preconditionRequired
> case tooManyRequests
> case requestHeaderFieldsTooLarge
> case unavailableForLegalReasons
> case internalServerError
> case notImplemented
> case badGateway
> case serviceUnavailable
> case gatewayTimeout
> case httpVersionNotSupported
> case variantAlsoNegotiates
> case insufficientStorage
> case loopDetected
> case notExtended
> case networkAuthenticationRequired
> }
>
> public enum HTTPMethod {
> case custom(method: String)
>
> /* everything that http_parser.[ch] supports */
> case DELETE
> case GET
> case HEAD
> case POST
> case PUT
> case CONNECT
> case OPTIONS
> case TRACE
> case COPY
> case LOCK
> case MKCOL
> case MOVE
> case PROPFIND
> case PROPPATCH
> case SEARCH
> case UNLOCK
> case BIND
> case REBIND
> case UNBIND
> case ACL
> case REPORT
> case MKACTIVITY
> case CHECKOUT
> case MERGE
> case MSEARCH
> case NOTIFY
> case SUBSCRIBE
> case UNSUBSCRIBE
> case PATCH
> case PURGE
> case MKCALENDAR
> case LINK
> case UNLINK
> }
> --- SNAP ---
>
> Here's the demo code for a simple echo server
>
> --- SNIP ---
> serve { (req, res) in
> if req.target == "/echo" {
> guard req.httpVersion == (1, 1) else {
> /* HTTP/1.0 doesn't support chunked encoding */
> res.writeResponse(HTTPResponse(version: req.version,
> status: .httpVersionNotSupported,
> transferEncoding: .identity(contentLength: 0)))
> res.done()
> return .discardBody
> }
> res.writeResponse(HTTPResponse(version: req.version,
> status: .ok,
> transferEncoding: .chunked,
> headers: SomeConcreteHTTPHeaders([("X-foo": "bar")])))
> return .processBody { (chunk, stop) in
> switch chunk {
> case .chunk(let data, let finishedProcessing):
> res.writeBody(data: data) { _ in
> finishedProcessing()
> }
> case .end:
> res.done()
> default:
> stop = true /* don't call us anymore */
> res.abort()
> }
> }
> } else { ... }
> }
> --- SNAP ---
>
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