Network.HTTP.Conduit

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. By using httpRedirect, it will automatically follow 3xx redirects.

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

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

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

Perform a request

simpleHttp :: ResourceIO m => String -> m ByteString

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. 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 write your own iteratee and use http or httpRedirect directly.

httpLbs :: ResourceIO m => Request m -> Manager -> ResourceT m Response

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 = http lbsConsumer

Please see lbsConsumer for more information on how the Response value is created.

Even though a 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 write your own iteratee and use http or httpRedirect directly.

httpLbsRedirect :: ResourceIO m => Request m -> Manager -> ResourceT m Response

Download the specified Request, returning the results as a Response and automatically handling redirects.

This is a simplified version of httpRedirect 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 httpRedirect directly. This function is defined as:

httpLbsRedirect = httpRedirect lbsConsumer

Please see lbsConsumer for more information on how the Response value is created.

Even though a 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 write your own iteratee and use http or httpRedirect directly.

http :: ResourceIO m => Request m -> ResponseConsumer m a -> Manager -> ResourceT m a

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 how the response should be handled. It's a function that takes two arguments: the first is the HTTP status code of the response, and the second is a list of all response headers. This module exports lbsConsumer, which generates a Response value.

Note that this allows you to have fully interleaved IO actions during your HTTP download, making it possible to download very large responses in constant memory.

httpRedirect :: ResourceIO m => Request m -> (Status -> ResponseHeaders -> BufferedSource m ByteString -> ResourceT m a) -> Manager -> ResourceT m a

Same as http, but follows all 3xx redirect status codes that contain a location header.

redirectConsumer

Arguments

:: ResourceIO m

=> Int

number of redirects to attempt

-> Request m

Original request

-> ResponseConsumer m a

-> Manager

-> ResponseConsumer m a

Make a request automatically follow 3xx redirects.

Used internally by httpRedirect and family.

Datatypes

data Proxy

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

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

A simple representation of the HTTP response created by lbsConsumer.

Constructors

Response

Fields

statusCode :: Int

responseHeaders :: ResponseHeaders

responseBody :: ByteString

Instances

Eq Response

Read Response

Show Response

Typeable Response

type ResponseConsumer m a = Status -> ResponseHeaders -> BufferedSource m ByteString -> ResourceT m a

Request

data Request m

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

HTTP request method, eg GET, POST.

secure :: Request m -> Bool

Whether to use HTTPS (ie, SSL).

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

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

host :: Request m -> Ascii

port :: Request m -> Int

path :: Request m -> Ascii

Everything from the host to the query string.

queryString :: Request m -> Ascii

requestHeaders :: Request m -> RequestHeaders

requestBody :: Request m -> RequestBody m

proxy :: Request m -> Maybe Proxy

Optional HTTP proxy.

rawBody :: Request m -> Bool

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

decompress :: Request m -> ContentType -> Bool

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

Defaults

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

Manager

data Manager

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

newManager :: ResourceIO m => ResourceT m Manager

Create a new Manager with no open connections.

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

Utility functions

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

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 m

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 m

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

lbsConsumer :: ResourceIO m => ResponseConsumer m Response

Convert the HTTP response into a Response value.

Even though a 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 write your own iteratee and use http or httpRedirect directly.

Decompression predicates

alwaysDecompress :: ContentType -> Bool

Always decompress a compressed stream.

browserDecompress :: ContentType -> Bool

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

Request bodies

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

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

Constructors

StatusCodeException Int ByteString

InvalidUrlException String String

TooManyRedirects

HttpParserException String

Instances

Show HttpException

Typeable HttpException

Exception HttpException