chromium/ipc/message_router.h

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef IPC_MESSAGE_ROUTER_H_
#define IPC_MESSAGE_ROUTER_H_

#include <stdint.h>

#include "base/component_export.h"
#include "base/containers/id_map.h"
#include "ipc/ipc_listener.h"
#include "ipc/ipc_sender.h"

// The MessageRouter handles all incoming messages sent to it by routing them
// to the correct listener.  Routing is based on the Message's routing ID.
// Since routing IDs are typically assigned asynchronously by the browser
// process, the MessageRouter has the notion of pending IDs for listeners that
// have not yet been assigned a routing ID.
//
// When a message arrives, the routing ID is used to index the set of routes to
// find a listener.  If a listener is found, then the message is passed to it.
// Otherwise, the message is ignored if its routing ID is not equal to
// MSG_ROUTING_CONTROL.
//
// The MessageRouter supports the IPC::Sender interface for outgoing messages,
// but does not define a meaningful implementation of it.  The subclass of
// MessageRouter is intended to provide that if appropriate.
//
// The MessageRouter can be used as a concrete class provided its Send method
// is not called and it does not receive any control messages.

namespace IPC {

class COMPONENT_EXPORT(IPC) MessageRouter : public Listener, public Sender { … };

}  // namespace IPC

#endif  // IPC_MESSAGE_ROUTER_H_