Improve handler interface and documentation

This change simplifies a little more the sub protocols mechanism.
Aliases have been removed. The renaming of loop handlers as long
polling handlers has been reverted.

Plain HTTP handlers now simply do their work in the init/2
callback. There is no specific code for them.

Loop handlers now follow the same return value as Websocket,
they use ok to continue and shutdown to stop.

Terminate reasons for all handler types have been documented.
The terminate callback is now appropriately called in all cases
(or should be).

Behaviors for all handler types have been moved in the module
that implement them. This means that cowboy_handler replaces
the cowboy_http_handler behavior, and similarly cowboy_loop
replaces cowboy_loop_handler, cowboy_websocket replaces
cowboy_websocket_handler. Finally cowboy_rest now has the
start of a behavior in it and will have the full list of
optional callbacks defined once Erlang 18.0 gets released.

The guide has been reorganized and should be easier to follow.

1 files changed, 0 insertions, 115 deletions

diff --git a/doc/src/guide/multipart_req.ezdoc b/doc/src/guide/multipart_req.ezdoc
deleted file mode 100644
index 21762f6..0000000
--- a/doc/src/guide/multipart_req.ezdoc
+++ /dev/null
@@ -1,115 +0,0 @@
-::: Multipart requests
-
-You can read and parse multipart messages using the
-Req object directly.
-
-Cowboy defines two functions that allows you to get
-information about each part and read their contents.
-
-:: Checking the content-type
-
-While there is a variety of multipart messages, the
-most common on the Web is `multipart/form-data`. It's
-the type of message being sent when an HTML form
-allows uploading files.
-
-You can quickly figure out if a multipart message
-has been sent by parsing the `content-type` header.
-
-``` erlang
-{<<"multipart">>, <<"form-data">>, _}
-    = cowboy_req:parse_header(<<"content-type">>, Req).
-```
-
-:: Reading a multipart message
-
-To read a message you have to iterate over all its
-parts. Then, for each part, you can inspect its headers
-and read its body.
-
-``` erlang
-multipart(Req) ->
-    case cowboy_req:part(Req) of
-        {ok, _Headers, Req2} ->
-            {ok, _Body, Req3} = cowboy_req:part_body(Req2),
-            multipart(Req3);
-        {done, Req2} ->
-            Req2
-    end.
-```
-
-Parts do not have a size limit. When a part body is
-too big, Cowboy will return what it read so far and
-allow you to continue if you wish to do so.
-
-The function `cow_multipart:form_data/1` can be used
-to quickly obtain information about a part from a
-`multipart/form-data` message. This function will
-tell you if the part is for a normal field or if it
-is a file being uploaded.
-
-This can be used for example to allow large part bodies
-for files but crash when a normal field is too large.
-
-``` erlang
-multipart(Req) ->
-    case cowboy_req:part(Req) of
-        {ok, Headers, Req2} ->
-            Req4 = case cow_multipart:form_data(Headers) of
-                {data, _FieldName} ->
-                    {ok, _Body, Req3} = cowboy_req:part_body(Req2),
-                    Req3;
-                {file, _FieldName, _Filename, _CType, _CTransferEncoding} ->
-                    stream_file(Req2)
-            end,
-            multipart(Req4);
-        {done, Req2} ->
-            Req2
-    end.
-
-stream_file(Req) ->
-    case cowboy_req:part_body(Req) of
-        {ok, _Body, Req2} ->
-            Req2;
-        {more, _Body, Req2} ->
-            stream_file(Req2)
-    end.
-```
-
-By default the body chunk Cowboy will return is limited
-to 8MB. This can of course be overriden. Both functions
-can take a second argument, the same list of options that
-will be passed to `cowboy_req:body/2` function.
-
-:: Skipping unwanted parts
-
-If you do not want to read a part's body, you can skip it.
-Skipping is easy. If you do not call the function to read
-the part's body, Cowboy will automatically skip it when
-you request the next part.
-
-The following snippet reads all part headers and skips
-all bodies:
-
-``` erlang
-multipart(Req) ->
-    case cowboy_req:part(Req) of
-        {ok, _Headers, Req2} ->
-            multipart(Req2);
-        {done, Req2} ->
-            Req2
-    end.
-```
-
-Similarly, if you start reading the body and it ends up
-being too big, you can simply continue with the next part,
-Cowboy will automatically skip what remains.
-
-Note that the skipping rate may not be adequate for your
-application. If you observe poor performance when skipping,
-you might want to consider manually skipping by calling
-the `cowboy_req:part_body/1` function directly.
-
-And if you started reading the message but decide that you
-do not need the remaining parts, you can simply stop reading
-entirely and Cowboy will automatically figure out what to do.