{-# LANGUAGE Rank2Types #-} {-# LANGUAGE CPP #-} {-| This module defines a generic web application interface. It is a common protocol between web servers and web applications. The overriding design principles here are performance and generality. To address performance, this library is built on top of the conduit and blaze-builder packages. The advantages of conduits over lazy IO have been debated elsewhere and so will not be addressed here. However, helper functions like 'responseLBS' allow you to continue using lazy IO if you so desire. Generality is achieved by removing many variables commonly found in similar projects that are not universal to all servers. The goal is that the 'Request' object contains only data which is meaningful in all circumstances. Please remember when using this package that, while your application may compile without a hitch against many different servers, there are other considerations to be taken when moving to a new backend. For example, if you transfer from a CGI application to a FastCGI one, you might suddenly find you have a memory leak. Conversely, a FastCGI application would be well served to preload all templates from disk when first starting; this would kill the performance of a CGI application. This package purposely provides very little functionality. You can find various middlewares, backends and utilities on Hackage. Some of the most commonly used include: [warp] [wai-extra] [wai-test] -} module Network.Wai ( -- * Types Application , Middleware -- * Request , Request , defaultRequest , RequestBodyLength (..) -- ** Request accessors , requestMethod , httpVersion , rawPathInfo , rawQueryString , requestHeaders , isSecure , remoteHost , pathInfo , queryString , requestBody , vault , requestBodyLength , requestHeaderHost , requestHeaderRange , lazyRequestBody -- * Response , Response , FilePart (..) , WithSource -- ** Response composers , responseFile , responseBuilder , responseLBS , responseSource , responseSourceBracket , responseRaw -- * Response accessors , responseStatus , responseHeaders , responseToSource ) where import Blaze.ByteString.Builder (Builder, fromLazyByteString) import Blaze.ByteString.Builder (fromByteString) import Control.Exception (bracket, bracketOnError) import qualified Data.ByteString as B import qualified Data.ByteString.Lazy as L import Data.ByteString.Lazy.Char8 () import qualified Data.Conduit as C import qualified Data.Conduit.Binary as CB import Data.Conduit.Lazy (lazyConsume) import qualified Data.Conduit.List as CL import Data.Monoid (mempty) import qualified Network.HTTP.Types as H import Network.Socket (SockAddr (SockAddrInet)) import Network.Wai.Internal import qualified System.IO as IO ---------------------------------------------------------------- -- | Creating 'Response' from a file. responseFile :: H.Status -> H.ResponseHeaders -> FilePath -> Maybe FilePart -> Response responseFile = ResponseFile -- | Creating 'Response' from 'Builder'. -- -- Some questions and answers about the usage of 'Builder' here: -- -- Q1. Shouldn't it be at the user's discretion to use Builders internally and -- then create a stream of ByteStrings? -- -- A1. That would be less efficient, as we wouldn't get cheap concatenation -- with the response headers. -- -- Q2. Isn't it really inefficient to convert from ByteString to Builder, and -- then right back to ByteString? -- -- A2. No. If the ByteStrings are small, then they will be copied into a larger -- buffer, which should be a performance gain overall (less system calls). If -- they are already large, then blaze-builder uses an InsertByteString -- instruction to avoid copying. -- -- Q3. Doesn't this prevent us from creating comet-style servers, since data -- will be cached? -- -- A3. You can force blaze-builder to output a ByteString before it is an -- optimal size by sending a flush command. responseBuilder :: H.Status -> H.ResponseHeaders -> Builder -> Response responseBuilder = ResponseBuilder -- | Creating 'Response' from 'L.ByteString'. This is a wrapper for -- 'responseBuilder'. responseLBS :: H.Status -> H.ResponseHeaders -> L.ByteString -> Response responseLBS s h = ResponseBuilder s h . fromLazyByteString -- | Creating 'Response' from 'C.Source'. responseSource :: H.Status -> H.ResponseHeaders -> C.Source IO (C.Flush Builder) -> Response responseSource st hs src = ResponseSource st hs ($ src) -- | Creating 'Response' with allocated resource safely released. -- -- * The first argument is an action to allocate resource. -- -- * The second argument is a function to release the resource. -- -- * The third argument is a function to create -- ('H.Status','H.ResponseHeaders','C.Source' 'IO' ('C.Flush' 'Builder')) -- from the resource. responseSourceBracket :: IO a -> (a -> IO ()) -> (a -> IO (H.Status ,H.ResponseHeaders ,C.Source IO (C.Flush Builder))) -> IO Response responseSourceBracket setup teardown action = bracketOnError setup teardown $ \resource -> do (st,hdr,src) <- action resource return $ ResponseSource st hdr $ \f -> bracket (return resource) teardown (\_ -> f src) -- | Create a response for a raw application. This is useful for \"upgrade\" -- situations such as WebSockets, where an application requests for the server -- to grant it raw network access. -- -- This function requires a backup response to be provided, for the case where -- the handler in question does not support such upgrading (e.g., CGI apps). -- -- In the event that you read from the request body before returning a -- @responseRaw@, behavior is undefined. -- -- Since 2.1.0 responseRaw :: (C.Source IO B.ByteString -> C.Sink B.ByteString IO () -> IO ()) -> Response -> Response responseRaw rawApp fallback = ResponseRaw ($ rawApp) fallback ---------------------------------------------------------------- -- | Accessing 'H.Status' in 'Response'. responseStatus :: Response -> H.Status responseStatus (ResponseFile s _ _ _) = s responseStatus (ResponseBuilder s _ _ ) = s responseStatus (ResponseSource s _ _ ) = s responseStatus (ResponseRaw _ res ) = responseStatus res -- | Accessing 'H.ResponseHeaders' in 'Response'. responseHeaders :: Response -> H.ResponseHeaders responseHeaders (ResponseFile _ hs _ _) = hs responseHeaders (ResponseBuilder _ hs _ ) = hs responseHeaders (ResponseSource _ hs _ ) = hs responseHeaders (ResponseRaw _ res) = responseHeaders res -- | Converting the body information in 'Response' to 'Source'. responseToSource :: Response -> (H.Status, H.ResponseHeaders, WithSource IO (C.Flush Builder) b) responseToSource (ResponseSource s h b) = (s, h, b) responseToSource (ResponseFile s h fp (Just part)) = (s, h, \f -> IO.withFile fp IO.ReadMode $ \handle -> f $ sourceFilePart handle part C.$= CL.map (C.Chunk . fromByteString)) responseToSource (ResponseFile s h fp Nothing) = (s, h, \f -> IO.withFile fp IO.ReadMode $ \handle -> f $ CB.sourceHandle handle C.$= CL.map (C.Chunk . fromByteString)) responseToSource (ResponseBuilder s h b) = (s, h, ($ CL.sourceList [C.Chunk b])) responseToSource (ResponseRaw _ res) = responseToSource res sourceFilePart :: IO.Handle -> FilePart -> C.Source IO B.ByteString sourceFilePart handle (FilePart offset count _) = CB.sourceHandleRange handle (Just offset) (Just count) ---------------------------------------------------------------- -- | The WAI application. type Application = Request -> IO Response -- | Middleware is a component that sits between the server and application. It -- can do such tasks as GZIP encoding or response caching. What follows is the -- general definition of middleware, though a middleware author should feel -- free to modify this. -- -- As an example of an alternate type for middleware, suppose you write a -- function to load up session information. The session information is simply a -- string map \[(String, String)\]. A logical type signature for this middleware -- might be: -- -- @ loadSession :: ([(String, String)] -> Application) -> Application @ -- -- Here, instead of taking a standard 'Application' as its first argument, the -- middleware takes a function which consumes the session information as well. type Middleware = Application -> Application -- | A default, blank request. -- -- Since 2.0.0 defaultRequest :: Request defaultRequest = Request { requestMethod = H.methodGet , httpVersion = H.http10 , rawPathInfo = B.empty , rawQueryString = B.empty , requestHeaders = [] , isSecure = False , remoteHost = SockAddrInet 0 0 , pathInfo = [] , queryString = [] , requestBody = return () , vault = mempty , requestBodyLength = KnownLength 0 , requestHeaderHost = Nothing , requestHeaderRange = Nothing } -- | Get the request body as a lazy ByteString. This uses lazy I\/O under the -- surface, and therefore all typical warnings regarding lazy I/O apply. -- -- Since 1.4.1 lazyRequestBody :: Request -> IO L.ByteString lazyRequestBody = fmap L.fromChunks . lazyConsume . requestBody