-- 4. The 'Resource' Monad and its thread stops running. The client
-- may or may not be sending us the next request at this point.
--
--- 'Resource' Monad is composed of the following states. The initial
--- state is /Examining Request/ and the final state is /Done/.
+-- 'Resource' Monad takes the following states. The initial state is
+-- /Examining Request/ and the final state is /Done/.
--
-- [/Examining Request/] In this state, a 'Resource' looks at the
-- request header and thinks about an entity for it. If there is a
-- and just throws it away.
--
-- [/Deciding Header/] A 'Resource' makes a decision of status code
--- and response headers. When it transits to the next state, ...
+-- and response header. When it transits to the next state, the
+-- system checks the validness of response header and then write
+-- them to the socket.
--
--- [/Deciding Body/]
+-- [/Deciding Body/] In this state, a 'Resource' asks the system to
+-- write some response body to the socket. When it transits to the
+-- next state without writing any response body, the system
+-- completes it depending on the status code.
--
--- [/Done/]
+-- [/Done/] Everything is over. A 'Resource' can do nothing for the
+-- HTTP interaction anymore.
+--
+-- Note that the state transition is one-way: for instance, it is an
+-- error to try to read a request body after writing some
+-- response. This limitation is for efficiency. We don't want to read
+-- the entire request before starting 'Resource', nor we don't want to
+-- postpone writing the entire response till the end of 'Resource'
+-- computation.
+module Network.HTTP.Lucu.Resource
+ (
+ -- * Monad
+ Resource
--- 一方通行であること、その理由
+ -- * Actions
--- FIXME: 續きを書く
-
-module Network.HTTP.Lucu.Resource
- ( Resource
+ -- ** Getting request header
+ -- |These actions can be computed regardless of the current state,
+ -- and they don't change the state.
, getConfig
, getRequest
, getMethod
, getAccept
, getContentType
+ -- ** Finding an entity
+
+ -- |These actions can be computed only in the /Examining Request/
+ -- state. After the computation, the 'Resource' transits to
+ -- /Getting Body/ state.
, foundEntity
, foundETag
, foundTimeStamp
, foundNoEntity
+ -- ** Getting a request body
+
+ -- |Computation of these actions changes the state to /Getting
+ -- Body/.
, input
, inputChunk
, inputBS
, inputForm
, defaultLimit
+ -- ** Setting response headers
+
+ -- |Computation of these actions changes the state to /Deciding
+ -- Header/.
, setStatus
, setHeader
, redirect
- , setETag
- , setLastModified
, setContentType
+ -- ** Writing a response body
+
+ -- |Computation of these actions changes the state to /Deciding
+ -- Body/.
, output
, outputChunk
, outputBS
import Network.URI
import System.Time
-
+-- |The 'Resource' monad. /Interaction/ is an internal state thus it
+-- is not exposed to users. This monad implements 'MonadIO' so it can
+-- do any IO actions.
type Resource a = ReaderT Interaction IO a
-
+-- |Get the 'Network.HTTP.Lucu.Config.Config' value which is used for
+-- the httpd.
getConfig :: Resource Config
getConfig = do itr <- ask
return $ itrConfig itr
-
+-- |Get the 'Network.HTTP.Lucu.Request.Request' value which represents
+-- the request header. In general you don't have to use this action.
getRequest :: Resource Request
getRequest = do itr <- ask
return $ fromJust $ itrRequest itr
-
+-- |Get the 'Network.HTTP.Lucu.Request.Method' value of the request.
getMethod :: Resource Method
getMethod = do req <- getRequest
return $ reqMethod req
-
+-- |Get the URI of the request.
getRequestURI :: Resource URI
getRequestURI = do req <- getRequest
return $ reqURI req
-
+-- |Get the path of this 'Resource' (to be exact,
+-- 'Network.HTTP.Lucu.Resource.Tree.ResourceDef') in the
+-- 'Network.HTTP.Lucu.Resource.Tree.ResTree'. The result of this
+-- action is the exact path in the tree even if the
+-- 'Network.HTTP.Lucu.Resource.Tree.ResourceDef' is greedy.
+--
+-- Example:
+--
+-- > main = let tree = mkResTree [ (["foo"], resFoo) ]
+-- > in runHttpd defaultConfig tree
+-- >
+-- > resFoo = ResourceDef {
+-- > resIsGreedy = True
+-- > , resGet = Just $ do requestURI <- getRequestURI
+-- > resourcePath <- getResourcePath
+-- > pathInfo <- getPathInfo
+-- > -- uriPath requestURI == "/foo/bar/baz"
+-- > -- resourcePath == ["foo"]
+-- > -- pathInfo == ["bar", "baz"]
+-- > ...
+-- > , ...
+-- > }
getResourcePath :: Resource [String]
getResourcePath = do itr <- ask
return $ fromJust $ itrResourcePath itr
+-- |This is an analogy of CGI PATH_INFO. Its result is always @[]@ if
+-- the 'Network.HTTP.Lucu.Resource.Tree.ResourceDef' is not
+-- greedy. See 'getResourcePath'.
getPathInfo :: Resource [String]
getPathInfo = do rsrcPath <- getResourcePath
reqURI <- getRequestURI
-- rsrcPath の長さの分だけ削除すれば良い。
return $ drop (length rsrcPath) reqPath
-
+-- |Get a value of given request header. Comparison of header name is
+-- case-insensitive. Note that this action is not intended to be used
+-- so frequently: there should be an action like 'getContentType' for
+-- every common headers.
getHeader :: String -> Resource (Maybe String)
getHeader name = do itr <- ask
return $ H.getHeader name $ fromJust $ itrRequest itr
-
+-- |Get a list of 'Network.HTTP.Lucu.MIMEType.MIMEType' enumerated on
+-- header \"Accept\".
getAccept :: Resource [MIMEType]
getAccept = do accept <- getHeader "Accept"
if accept == Nothing then
(Success xs, _) -> return xs
_ -> return []
-
+-- |Get the header \"Content-Type\" as
+-- 'Network.HTTP.Lucu.MIMEType.MIMEType'.
getContentType :: Resource (Maybe MIMEType)
getContentType = do cType <- getHeader "Content-Type"
if cType == Nothing then
{- ExaminingRequest 時に使用するアクション群 -}
+-- |Tell the system that the 'Resource' found an entity for the
+-- request URI. If this is a GET or HEAD request, a found entity means
+-- a datum to be replied. If this is a PUT or DELETE request, it means
+-- a datum which was stored for the URI up to now. It is an error to
+-- compute 'foundEntity' if this is a POST request.
+--
+-- Computation of 'foundEntity' performs \"If-Match\" test or
+-- \"If-None-Match\" test if possible. When those tests fail, the
+-- computation of 'Resource' immediately aborts with status \"412
+-- Precondition Failed\" or \"304 Not Modified\" depending on the
+-- situation.
+--
+-- If this is a GET or HEAD request, 'foundEntity' automatically puts
+-- \"ETag\" and \"Last-Modified\" headers into the response.
foundEntity :: ETag -> ClockTime -> Resource ()
foundEntity tag timeStamp
= do driftTo ExaminingRequest
method <- getMethod
when (method == GET || method == HEAD)
$ setHeader' "Last-Modified" $ formatHTTPDateTime timeStamp
+ when (method == POST)
+ $ abort InternalServerError []
+ (Just "Illegal computation of foundEntity for POST request.")
foundETag tag
driftTo GettingBody
-
+-- |Tell the system that the 'Resource' found an entity for the
+-- request URI. The only difference from 'foundEntity' is that
+-- 'foundETag' doesn't (and can't) put \"Last-Modified\" header into
+-- the response.
+--
+-- This action is not preferred. You should use 'foundEntity' when
+-- possible.
foundETag :: ETag -> Resource ()
foundETag tag
= do driftTo ExaminingRequest
method <- getMethod
when (method == GET || method == HEAD)
$ setHeader' "ETag" $ show tag
+ when (method == POST)
+ $ abort InternalServerError []
+ (Just "Illegal computation of foundETag for POST request.")
-- If-Match があればそれを見る。
ifMatch <- getHeader "If-Match"
driftTo GettingBody
-
+-- |Tell the system that the 'Resource' found an entity for the
+-- request URI. The only difference from 'foundEntity' is that
+-- 'foundTimeStamp' performs \"If-Modified-Since\" test or
+-- \"If-Unmodified-Since\" test instead of \"If-Match\" test or
+-- \"If-None-Match\" test. Be aware that any tests based on last
+-- modification time are unsafe because it is possible to mess up such
+-- tests by modifying the entity twice in a second.
+--
+-- This action is not preferred. You should use 'foundEntity' when
+-- possible.
foundTimeStamp :: ClockTime -> Resource ()
foundTimeStamp timeStamp
= do driftTo ExaminingRequest
method <- getMethod
when (method == GET || method == HEAD)
$ setHeader' "Last-Modified" $ formatHTTPDateTime timeStamp
+ when (method == POST)
+ $ abort InternalServerError []
+ (Just "Illegal computation of foundTimeStamp for POST request.")
let statusForIfModSince = if method == GET || method == HEAD then
NotModified
driftTo GettingBody
-
+-- |Computation of @'foundNoEntity' mStr@ tell the system that the
+-- 'Resource' found no entity for the request URI. @mStr@ is an
+-- optional error message to be replied to the client.
+--
+-- If this is a PUT request, 'foundNoEntity' performs \"If-Match\"
+-- test and aborts with status \"412 Precondition Failed\" when it
+-- failed. If this is a GET, HEAD or DELETE request, 'foundNoEntity'
+-- always aborts with status \"404 Not Found\". It is an error to
+-- compute 'foundNoEntity' if this is a POST request.
foundNoEntity :: Maybe String -> Resource ()
foundNoEntity msgM
= do driftTo ExaminingRequest
method <- getMethod
+ when (method == POST)
+ $ abort InternalServerError []
+ (Just "Illegal computation of foundNoEntity for POST request.")
when (method /= PUT)
- $ abort NotFound [] msgM
+ $ abort NotFound [] msgM
-- エンティティが存在しないと云ふ事は、"*" も含めたどのやうな
-- If-Match: 條件も滿たさない。
resStatus = code
}
-
+-- | Set a value of given resource header. Comparison of header name
+-- is case-insensitive. Note that this action is not intended to be
+-- used so frequently: there should be an action like 'setContentType'
+-- for every common headers.
+--
+-- Some important headers (especially \"Content-Length\" and
+-- \"Transfer-Encoding\") may be silently deleted or overwritten by
+-- the system not to corrupt the interaction with client at the
+-- viewpoint of HTTP protocol. For instance, if we are keeping
+-- connection alive, for an obvious reason it causes a catastrophe to
+-- send header \"Content-Length: 10\" and actually sending body of 20
+-- bytes long.
setHeader :: String -> String -> Resource ()
setHeader name value
= driftTo DecidingHeader >> setHeader' name value
setHeader "Location" (uriToString id uri $ "")
-setETag :: ETag -> Resource ()
-setETag tag
- = setHeader "ETag" $ show tag
-
-
-setLastModified :: ClockTime -> Resource ()
-setLastModified lastmod
- = setHeader "Last-Modified" $ formatHTTPDateTime lastmod
-
-
setContentType :: MIMEType -> Resource ()
setContentType mType
= setHeader "Content-Type" $ show mType
projects / Lucu.git / blobdiff