Add a skeleton of the guide to ease user contributions

Has some stuff that aren't in master yet, and lacks a lot more
that is already in master.

11 files changed, 353 insertions, 10 deletions

diff --git a/guide/handlers.md b/guide/handlers.md
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+Handlers
+========
+
+Purpose
+-------
+
+Handlers are Erlang modules that represent a resource.
+
+Handlers must process the request and send a reply. The nature of the
+reply will vary between handlers.
+
+Different kinds of handlers can be combined in a single module. This
+allows a module to handle both websocket and long-polling code in a
+single place, for example.
+
+Protocol upgrades
+-----------------
+
+Cowboy features many different handlers: HTTP handlers, loop handlers,
+websocket handlers, REST handlers and static handlers. All of them
+have a common entry point: the `init/3` function.
+
+By default, Cowboy considers your handler to be an HTTP handler.
+
+To switch to a different protocol, like, for example, Websocket,
+you must perform a protocol upgrade. This is done by returning
+a protocol upgrade tuple at the end of `init/3`.
+
+The following snippet upgrades the handler to `my_protocol`.
+
+``` erlang
+init(_Any, _Req, _Opts) ->
+    {upgrade, protocol, my_protocol}.
+```
+
+The `my_protocol` module will be used for further processing of the
+request. It requires only one callback, `upgrade/4`.
+
+@todo Describe `upgrade/4` when the middleware code gets pushed.
diff --git a/guide/hooks.md b/guide/hooks.md
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+Hooks
+=====
+
+On request
+----------
+
+@todo Describe.
+
+On response
+-----------
+
+@todo Describe.
diff --git a/guide/http_handlers.md b/guide/http_handlers.md
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+HTTP handlers
+=============
+
+Purpose
+-------
+
+HTTP handlers are the simplest Cowboy module to handle a request.
+
+Callbacks
+---------
+
+@todo Describe the callbacks.
+
+Usage
+-----
+
+@todo Explain how to use them.
diff --git a/guide/internals.md b/guide/internals.md
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+Internals
+=========
+
+Architecture
+------------
+
+@todo Describe.
+
+Efficiency considerations
+-------------------------
+
+@todo Mention that you need to cleanup in terminate especially if you
+used the process dictionary, started timers, started monitoring...
diff --git a/guide/loop_handlers.md b/guide/loop_handlers.md
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+Loop handlers
+=============
+
+Purpose
+-------
+
+Loop handlers are a special kind of HTTP handlers used when the
+response can not be sent right away. The handler enters instead
+a receive loop waiting for the right message before it can send
+a response.
+
+They are most useful when performing long-polling operations or
+when using server-sent events.
+
+Callbacks
+---------
+
+@todo Describe the callbacks.
+
+Usage
+-----
+
+@todo Explain how to use them.
diff --git a/guide/req.md b/guide/req.md
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+Request object
+==============
+
+Purpose
+-------
+
+@todo Describe.
+
+Request
+-------
+
+@todo Describe.
+
+Request body
+------------
+
+@todo Describe.
+
+Reply
+-----
+
+@todo Describe.
diff --git a/guide/rest_handlers.md b/guide/rest_handlers.md
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+REST handlers
+=============
+
+Purpose
+-------
+
+REST is a set of constraints that, when applied to HTTP, dictates how
+resources must behave. It is the recommended way to handle requests
+with Cowboy.
+
+REST is implemented in Cowboy as a protocol upgrade. Once upgraded,
+the request is handled as a state machine with many optional callbacks
+describing the resource and modifying the machine's behavior.
+
+Flow diagram
+------------
+
+@todo Add the beautiful flow diagram here.
+
+Callbacks
+---------
+
+@todo Describe the callbacks.
+
+Usage
+-----
+
+@todo Explain how to use them.
diff --git a/guide/routing.md b/guide/routing.md
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+++ b/guide/routing.md
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+Routing
+=======
+
+@todo Note that this documentation is for the new routing interface
+not available in master at this point.
+
+Purpose
+-------
+
+Cowboy does nothing by default.
+
+To make Cowboy useful, you need to map URLs to Erlang modules that will
+handle the requests. This is called routing.
+
+When Cowboy receives a request, it tries to match the requested host and
+path to the resources given in the dispatch rules. If it matches, then
+the associated Erlang code will be executed.
+
+Routing rules are given per host. Cowboy will first match on the host,
+and then try to find a matching path.
+
+Routes need to be compiled before they can be used by Cowboy.
+
+Structure
+---------
+
+The general structure for the routes is defined as follow.
+
+``` erlang
+Routes = [Host1, Host2, ... HostN].
+```
+
+Each host contains matching rules for the host along with optional
+constraints, and a list of routes for the path component.
+
+``` erlang
+Host1 = {HostMatch, PathsList}.
+Host2 = {HostMatch, Constraints, PathsList}.
+```
+
+The list of routes for the path component is defined similar to the
+list of hosts.
+
+``` erlang
+PathsList = [Path1, Path2, ... PathN].
+```
+
+Finally, each path contains matching rules for the path along with
+optional constraints, and gives us the handler module to be used
+along with options that will be given to it on initialization.
+
+```
+Path1 = {PathMatch, Handler, Module}.
+Path2 = {PathMatch, Constraints, Handler, Module}.
+```
+
+Continue reading to learn more about the match syntax and the optional
+constraints.
+
+Match syntax
+------------
+
+The match syntax is used to associate host names and paths with their
+respective handlers.
+
+The match syntax is the same for host and path with a few subtleties.
+Indeed, the segments separator is different, and the host is matched
+starting from the last segment going to the first. All examples will
+feature both host and path match rules and explain the differences
+when encountered.
+
+Excluding special values that we will explain at the end of this section,
+the simplest match value is a host or a path. It can be given as either
+a `string()` or a `binary()`.
+
+``` erlang
+PathMatch1 = "/".
+PathMatch2 = "/path/to/resource".
+
+HostMatch1 = "cowboy.example.org".
+```
+
+As you can see, all paths defined this way must start with a slash
+character. Note that these two paths are identical as far as routing
+is concerned.
+
+``` erlang
+PathMatch2 = "/path/to/resource".
+PathMatch3 = "/path/to/resource/".
+```
+
+Hosts with and without a trailing dot are equivalent for routing.
+
+``` erlang
+HostMatch1 = "cowboy.example.org".
+HostMatch2 = "cowboy.example.org.".
+```
+
+It is possible to extract segments of the host and path and to store
+the values in the `Req` object for later use. We call these kind of
+values bindings.
+
+The syntax for bindings is very simple. A segment that begins with
+the `:` character means that what follows until the end of the segment
+is the name of the binding in which the segment value will be stored.
+
+``` erlang
+PathMatch = "/hats/:name/prices".
+HostMatch = ":subdomain.example.org".
+```
+
+If these two end up matching when routing, you will end up with two
+bindings defined, `subdomain` and `hat_name`, each containing the
+segment value where they were defined. For example, the URL
+`http://test.example.org/hats/wild_cowboy_legendary/prices` will
+result in having the value `test` bound to the name `subdomain`
+and the value `wild_cowboy_legendary` bound to the name `hat_name`.
+They can later be retrieved using `cowboy_req:binding/{2,3}`.
+
+@todo special binding `'_'`
+@todo optional path or segments
+@todo same binding twice (+ optional + host/path)
+
+Constraints
+-----------
+
+@todo Describe constraints.
+
+Compilation
+-----------
+
+The structure defined in this chapter needs to be compiled before it is
+passed to Cowboy. This allows Cowboy to efficiently lookup the correct
+handler to run instead of having to parse the routes repeatedly.
+
+This can be done with a simple call to `cowboy_routing:compile/1`.
+
+@todo Note that the `routes` option will be specified slightly differently
+when middleware support gets in.
+
+``` erlang
+{ok, Routes} = cowboy_routing:compile([
+    %% {URIHost, list({URIPath, Handler, Opts})}
+    {'_', [{'_', my_handler, []}]}
+]),
+%% Name, NbAcceptors, TransOpts, ProtoOpts
+cowboy:start_http(my_http_listener, 100,
+    [{port, 8080}],
+    [{routes, Routes}]
+).
+```
+
+Note that this function will return `{error, badarg}` if the structure
+given is incorrect.
diff --git a/guide/static_handlers.md b/guide/static_handlers.md
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+Static handlers
+===============
+
+Purpose
+-------
+
+Static handlers are a built-in REST handler for serving files. They
+are available as a convenience and provide fast file serving with
+proper cache handling.
+
+Usage
+-----
+
+@todo Describe.
diff --git a/guide/toc.md b/guide/toc.md
index b57b92e..32234cd 100644
--- a/guide/toc.md
+++ b/guide/toc.md
@@ -6,43 +6,43 @@ Cowboy User Guide
    *  Prerequisites
    *  Conventions
    *  Getting started
- *  Routing
+ *  [Routing](routing.md)
    *  Purpose
    *  Dispatch list
    *  Match rules
    *  Bindings
    *  Constraints
- *  Handlers
+ *  [Handlers](handlers.md)
    *  Purpose
    *  Protocol upgrades
- *  HTTP handlers
+ *  [HTTP handlers](http_handlers.md)
    *  Purpose
    *  Callbacks
    *  Usage
- *  Loop handlers
+ *  [Loop handlers](loop_handlers.md)
    *  Purpose
    *  Callbacks
    *  Usage
- *  Websocket handlers
+ *  [Websocket handlers](ws_handlers.md)
    *  Purpose
    *  Callbacks
    *  Usage
- *  REST handlers
+ *  [REST handlers](rest_handlers.md)
    *  Purpose
    *  Flow diagram
    *  Callbacks
    *  Usage
- *  Static handlers
+ *  [Static handlers](static_handlers.md)
    *  Purpose
    *  Usage
- *  Request object
+ *  [Request object](req.md)
    *  Purpose
    *  Request
    *  Request body
    *  Reply
- *  Hooks
+ *  [Hooks](hooks.md)
    *  On request
    *  On response
- *  Internals
+ *  [Internals](internals.md)
    *  Architecture
    *  Efficiency considerations
diff --git a/guide/ws_handlers.md b/guide/ws_handlers.md
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+Websocket handlers
+==================
+
+Purpose
+-------
+
+Websockets are an extension to HTTP to emulate plain TCP connections
+between the user's browser and the server. Requests that are upgraded
+are then handled by websocket handlers.
+
+Both sides of the socket can send data at any time asynchronously.
+
+Callbacks
+---------
+
+@todo Describe the callbacks.
+
+Usage
+-----
+
+@todo Explain how to use them.