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      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 service_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_
     90