Network.HTTP.Conduit

Contents

Description

This module contains everything you need to initiate HTTP connections. If you want a simple interface based on URLs, you can use simpleHttp. If you want raw power, http is the underlying workhorse of this package. Some examples:

 -- Just download an HTML document and print it.
 import Network.HTTP.Conduit
 import qualified Data.ByteString.Lazy as L

 main = simpleHttp "http://www.haskell.org/" >>= L.putStr

This example uses interleaved IO to write the response body to a file in constant memory space.

 import Data.Conduit.Binary (sinkFile)
 import Network.HTTP.Conduit
 import System.IO
 import qualified Data.Conduit as C

 main :: IO ()
 main = do
     request <- parseUrl "http://google.com/"
     withManager $ \manager -> do
         Response _ _ bsrc <- http request handler manager
         bsrc C.$$ sinkFile "google.html"

The following headers are automatically set by this module, and should not be added to requestHeaders:

Content-Length
Host
Accept-Encoding (not currently set, but client usage of this variable will cause breakage).

Any network code on Windows requires some initialization, and the network library provides withSocketsDo to perform it. Therefore, proper usage of this library will always involve calling that function at some point. The best approach is to simply call them at the beginning of your main function, such as:

 import Network.HTTP.Conduit
 import qualified Data.ByteString.Lazy as L
 import Network (withSocketsDo)

 main = withSocketsDo
      $ simpleHttp "http://www.haskell.org/" >>= L.putStr

Synopsis

Perform a request

simpleHttp :: MonadIO m => String -> m ByteString Source

Download the specified URL, following any redirects, and return the response body.

This function will throwIO an HttpException for any response with a non-2xx status code (besides 3xx redirects up to a limit of 10 redirects). It uses parseUrl to parse the input. This function essentially wraps httpLbsRedirect.

Note: Even though this function returns a lazy bytestring, it does not utilize lazy I/O, and therefore the entire response body will live in memory. If you want constant memory usage, you'll need to use the conduit package and http or httpRedirect directly.

httpLbs :: ResourceIO m => Request m -> Manager -> ResourceT m (Response ByteString)Source

Download the specified Request, returning the results as a Response.

This is a simplified version of http for the common case where you simply want the response data as a simple datatype. If you want more power, such as interleaved actions on the response body during download, you'll need to use http directly. This function is defined as:

httpLbs = lbsResponse . http

Even though the Response contains a lazy bytestring, this function does not utilize lazy I/O, and therefore the entire response body will live in memory. If you want constant memory usage, you'll need to use conduit packages's BufferedSource returned by http.

Note: Unlike previous versions, this function will perform redirects, as specified by the redirectCount setting.

http :: ResourceIO m => Request m -> Manager -> ResourceT m (Response (BufferedSource m ByteString))Source

The most low-level function for initiating an HTTP request.

The first argument to this function gives a full specification on the request: the host to connect to, whether to use SSL, headers, etc. Please see Request for full details. The second argument specifies which Manager should be used.

This function then returns a Response with a BufferedSource. The Response contains the status code and headers that were sent back to us, and the BufferedSource contains the body of the request. Note that this BufferedSource allows you to have fully interleaved IO actions during your HTTP download, making it possible to download very large responses in constant memory. You may also directly connect the returned BufferedSource into a Sink, perhaps a file or another socket.

Note: Unlike previous versions, this function will perform redirects, as specified by the redirectCount setting.

Datatypes

data Proxy Source

Define a HTTP proxy, consisting of a hostname and port number.

Constructors

Proxy
Fields proxyHost :: Ascii The host name of the HTTP proxy. proxyPort :: Int The port number of the HTTP proxy.

data RequestBody m Source

When using one of the 'RequestBodySource'\/'RequestBodySourceChunked' constructors and any function which calls redirectIter, you must ensure that the Source can be called multiple times. Usually this is not a problem.

The RequestBodySourceChunked will send a chunked request body, note that not all servers support this. Only use RequestBodySourceChunked if you know the server you're sending to supports chunked request bodies.

Constructors

RequestBodyLBS ByteString
RequestBodyBS ByteString
RequestBodyBuilder Int64 Builder
RequestBodySource Int64 (Source m Builder)
RequestBodySourceChunked (Source m Builder)

data Response body Source

A simple representation of the HTTP response created by lbsConsumer.

Constructors

Response
Fields statusCode :: Status responseHeaders :: ResponseHeaders responseBody :: body

Instances

Typeable1 Response
Eq body => Eq (Response body)
Show body => Show (Response body)

Request

data Request m Source

All information on how to connect to a host and what should be sent in the HTTP request.

If you simply wish to download from a URL, see parseUrl.

The constructor for this data type is not exposed. Instead, you should use either the def method to retrieve a default instance, or parseUrl to construct from a URL, and then use the records below to make modifications. This approach allows http-conduit to add configuration options without breaking backwards compatibility.

Instances

Default (Request m)

def :: Default a => a

The default value for this type.

method :: Request m -> Method Source

HTTP request method, eg GET, POST.

secure :: Request m -> Bool Source

Whether to use HTTPS (ie, SSL).

checkCerts :: Request m -> Ascii -> [X509] -> IO TLSCertificateUsage Source

Check if the server certificate is valid. Only relevant for HTTPS.

host :: Request m -> Ascii Source

port :: Request m -> Int Source

path :: Request m -> Ascii Source

Everything from the host to the query string.

queryString :: Request m -> Ascii Source

requestHeaders :: Request m -> RequestHeaders Source

requestBody :: Request m -> RequestBody mSource

proxy :: Request m -> Maybe Proxy Source

Optional HTTP proxy.

rawBody :: Request m -> Bool Source

If True, a chunked and/or gzipped body will not be decoded. Use with caution.

decompress :: Request m -> ContentType -> Bool Source

Predicate to specify whether gzipped data should be decompressed on the fly (see alwaysDecompress and browserDecompress). Default: browserDecompress.

redirectCount :: Request m -> Int Source

How many redirects to follow when getting a resource. 0 means follow no redirects. Default value: 10.

checkStatus :: Request m -> Status -> ResponseHeaders -> Maybe SomeException Source

Check the status code. Note that this will run after all redirects are performed. Default: return a StatusCodeException on non-2XX responses.

Defaults

defaultCheckCerts :: Ascii -> [X509] -> IO TLSCertificateUsage Source

Manager

data Manager Source

Keeps track of open connections for keep-alive. May be used concurrently by multiple threads.

newManager :: ResourceIO m => ResourceT m Manager Source

Create a new Manager with no open connections.

withManager :: ResourceIO m => (Manager -> ResourceT m a) -> m aSource

Utility functions

parseUrl :: Failure HttpException m => String -> m (Request m')Source

Convert a URL into a Request.

This defaults some of the values in Request, such as setting method to GET and requestHeaders to [].

Since this function uses Failure, the return monad can be anything that is an instance of Failure, such as IO or Maybe.

applyBasicAuth :: ByteString -> ByteString -> Request m -> Request mSource

Add a Basic Auth header (with the specified user name and password) to the given Request. Ignore error handling:

applyBasicAuth user pass $ fromJust $ parseUrl url

addProxy :: ByteString -> Int -> Request m -> Request mSource

Add a proxy to the the Request so that the Request when executed will use the provided proxy.

Decompression predicates

alwaysDecompress :: ContentType -> Bool Source

Always decompress a compressed stream.

browserDecompress :: ContentType -> Bool Source

Decompress a compressed stream unless the content-type is 'application/x-tar'.

Request bodies

urlEncodedBody :: Monad m => [(ByteString, ByteString)] -> Request m' -> Request mSource

Add url-encoded paramters to the Request.

This sets a new requestBody, adds a content-type request header and changes the method to POST.

Exceptions

data HttpException Source

Constructors

StatusCodeException Status ResponseHeaders
InvalidUrlException String String
TooManyRedirects
HttpParserException String

Instances

Show HttpException
Typeable HttpException
Exception HttpException