mojo/shell/dbus_service_loader_linux.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MOJO_SHELL_DBUS_SERVICE_LOADER_H_
   6 #define MOJO_SHELL_DBUS_SERVICE_LOADER_H_
   7
   8 #include <map>
   9
  10 #include "base/macros.h"
  11 #include "base/memory/ref_counted.h"
  12 #include "mojo/public/cpp/system/core.h"
  13 #include "mojo/service_manager/service_loader.h"
  14 #include "mojo/shell/keep_alive.h"
  15 #include "url/gurl.h"
  16
  17 namespace dbus {
  18 class Bus;
  19 }  // namespace dbus
  20
  21 namespace mojo {
  22 namespace shell {
  23
  24 class Context;
  25
  26 // An implementation of ServiceLoader that contacts a system service
  27 // and bootstraps a Mojo connection to it over DBus.
  28 //
  29 // In order to allow the externally-running service to accept connections from
  30 // a Mojo shell, we need to get it a ShellHandle. This class creates a
  31 // dedicated MessagePipe, passes a handle to one end to the desired service
  32 // over DBus, and then passes the ShellHandle over that pipe.
  33 //
  34 // This class assumes the following:
  35 // 1) Your service is already running.
  36 // 2) Your service implements the Mojo ExternalService API
  37 //    (from external_service.mojom).
  38 // 3) Your service exports an object that implements the org.chromium.Mojo DBus
  39 //    interface:
  40 //    <interface name="org.chromium.Mojo">
  41 //      <method name="ConnectChannel">
  42 //        <arg type="h" name="file_descriptor" direction="in" />
  43 //      </method>
  44 //    </interface>
  45 class DBusServiceLoader : public ServiceLoader {
  46  public:
  47   DBusServiceLoader(Context* context);
  48   virtual ~DBusServiceLoader();
  49
  50   // URL for DBus services are of the following format:
  51   // dbus:tld.domain.ServiceName/path/to/DBusObject
  52   //
  53   // This is simply the scheme (dbus:) and then the DBus service name followed
  54   // by the DBus object path of an object that implements the org.chromium.Mojo
  55   // interface as discussed above.
  56   //
  57   // Example:
  58   //   dbus:org.chromium.EchoService/org/chromium/MojoImpl
  59   //
  60   // This will tell DBusServiceLoader to reach out to a service with
  61   // the name "org.chromium.EchoService" and invoke the method
  62   // "org.chromium.Mojo.ConnectChannel" on the object exported at
  63   // "/org/chromium/MojoImpl".
  64   virtual void LoadService(ServiceManager* manager,
  65                            const GURL& url,
  66                            ScopedMessagePipeHandle shell_handle) OVERRIDE;
  67
  68   virtual void OnServiceError(ServiceManager* manager, const GURL& url)
  69       OVERRIDE;
  70
  71  private:
  72   class LoadContext;
  73
  74   // Tosses out connection-related state to service at given URL.
  75   void ForgetService(const GURL& url);
  76
  77   Context* const context_;
  78   scoped_refptr<dbus::Bus> bus_;
  79
  80   typedef std::map<GURL, LoadContext*> LoadContextMap;
  81   LoadContextMap url_to_load_context_;
  82
  83   DISALLOW_COPY_AND_ASSIGN(DBusServiceLoader);
  84 };
  85
  86 }  // namespace shell
  87 }  // namespace mojo
  88
  89 #endif  // MOJO_SHELL_DBUS_SERVICE_LOADER_H_