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.

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

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

Perform a request

simpleHttp :: MonadIO 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 (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)

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 Source 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 (Source m ByteString))

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 Source. The Response contains the status code and headers that were sent back to us, and the Source contains the body of the request. Note that this Source 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 Source 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

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, 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

A simple representation of the HTTP response created by lbsConsumer.

Constructors

Response

Fields

statusCode :: Status

responseHeaders :: ResponseHeaders

responseBody :: body

Instances

Functor Response

Since 1.1.2.

Typeable1 Response

Eq body => Eq (Response body)

Show body => Show (Response body)

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).

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). Default: browserDecompress.

redirectCount :: Request m -> Int

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

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

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

Manager

data Manager

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

newManager :: ManagerSettings -> IO Manager

Create a Manager. You must manually call closeManager to shut it down.

closeManager :: Manager -> IO ()

Close all connections in a Manager. Afterwards, the Manager can be reused if desired.

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

Create a new manager, use it in the provided function, and then release it.

This function uses the default manager settings. For more control, use newManager.

Settings

data ManagerSettings

Settings for a Manager. Please use the def function and then modify individual settings.

Instances

Default ManagerSettings

managerConnCount :: ManagerSettings -> Int

Number of connections to a single host to keep alive. Default: 10.

managerCheckCerts :: ManagerSettings -> Ascii -> [X509] -> IO TLSCertificateUsage

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

Defaults

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

Check certificates using the operating system's certificate checker.

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.

lbsResponse :: Resource m => ResourceT m (Response (Source m ByteString)) -> ResourceT m (Response ByteString)

Convert a Response that has a Source body to one with a lazy ByteString body.

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 Status ResponseHeaders

InvalidUrlException String String

TooManyRedirects

HttpParserException String

Instances

Show HttpException

Typeable HttpException

Exception HttpException