Enhance the DBus interface for peerd

Add ability to query properties of
 - Manager
 - Peer
 - Service
Add Observer to peerd so we are told when things change.

BUG=453873

Review URL: https://codereview.chromium.org/893663002

Cr-Commit-Position: refs/heads/master@{#315311}

4 files changed, 404 insertions, 33 deletions

diff --git a/chromeos/dbus/fake_peer_daemon_manager_client.cc b/chromeos/dbus/fake_peer_daemon_manager_client.cc
index 4eb1606..7424ebc 100644
--- a/chromeos/dbus/fake_peer_daemon_manager_client.cc
+++ b/chromeos/dbus/fake_peer_daemon_manager_client.cc
@@ -15,6 +15,32 @@ FakePeerDaemonManagerClient::~FakePeerDaemonManagerClient() {
 void FakePeerDaemonManagerClient::Init(dbus::Bus* bus) {
 }
 
+void FakePeerDaemonManagerClient::AddObserver(Observer* observer) {
+}
+
+void FakePeerDaemonManagerClient::RemoveObserver(Observer* observer) {
+}
+
+std::vector<dbus::ObjectPath> FakePeerDaemonManagerClient::GetPeers() {
+  return std::vector<dbus::ObjectPath>();
+}
+
+std::vector<dbus::ObjectPath> FakePeerDaemonManagerClient::GetServices() {
+  return std::vector<dbus::ObjectPath>();
+}
+
+PeerDaemonManagerClient::PeerProperties*
+FakePeerDaemonManagerClient::GetPeerProperties(
+    const dbus::ObjectPath& object_path) {
+  return nullptr;
+}
+
+PeerDaemonManagerClient::ServiceProperties*
+FakePeerDaemonManagerClient::GetServiceProperties(
+    const dbus::ObjectPath& object_path) {
+  return nullptr;
+}
+
 void FakePeerDaemonManagerClient::StartMonitoring(
     const std::vector<std::string>& requested_technologies,
     const base::DictionaryValue& options,
diff --git a/chromeos/dbus/fake_peer_daemon_manager_client.h b/chromeos/dbus/fake_peer_daemon_manager_client.h
index a4b16fa..c2c2717 100644
--- a/chromeos/dbus/fake_peer_daemon_manager_client.h
+++ b/chromeos/dbus/fake_peer_daemon_manager_client.h
@@ -24,6 +24,14 @@ class FakePeerDaemonManagerClient : public PeerDaemonManagerClient {
   void Init(dbus::Bus* bus) override;
 
   // PeerDaemonManagerClient overrides:
+  void AddObserver(Observer* observer) override;
+  void RemoveObserver(Observer* observer) override;
+  std::vector<dbus::ObjectPath> GetPeers() override;
+  std::vector<dbus::ObjectPath> GetServices() override;
+  PeerProperties* GetPeerProperties(
+      const dbus::ObjectPath& object_path) override;
+  ServiceProperties* GetServiceProperties(
+      const dbus::ObjectPath& object_path) override;
   void StartMonitoring(const std::vector<std::string>& requested_technologies,
                        const base::DictionaryValue& options,
                        const StringDBusMethodCallback& callback) override;
diff --git a/chromeos/dbus/peer_daemon_manager_client.cc b/chromeos/dbus/peer_daemon_manager_client.cc
index b2ba214..9fdea05 100644
--- a/chromeos/dbus/peer_daemon_manager_client.cc
+++ b/chromeos/dbus/peer_daemon_manager_client.cc
@@ -8,8 +8,11 @@
 #include "base/callback.h"
 #include "base/logging.h"
 #include "base/memory/weak_ptr.h"
+#include "base/message_loop/message_loop.h"
+#include "base/observer_list.h"
 #include "dbus/bus.h"
 #include "dbus/message.h"
+#include "dbus/object_manager.h"
 #include "dbus/object_proxy.h"
 #include "dbus/values_util.h"
 
@@ -19,8 +22,11 @@ namespace {
 // TODO(benchan): Move these constants to system_api.
 namespace peerd {
 const char kPeerdServiceName[] = "org.chromium.peerd";
+const char kPeerdObjectManagerServicePath[] = "/org/chromium/peerd";
 const char kPeerdManagerPath[] = "/org/chromium/peerd/Manager";
 const char kManagerInterface[] = "org.chromium.peerd.Manager";
+const char kServiceInterface[] = "org.chromium.peerd.Service";
+const char kPeerInterface[] = "org.chromium.peerd.Peer";
 const char kStartMonitoringMethod[] = "StartMonitoring";
 const char kStopMonitoringMethod[] = "StopMonitoring";
 const char kExposeServiceMethod[] = "ExposeService";
@@ -29,15 +35,24 @@ const char kPingMethod[] = "Ping";
 }  // namespace peerd
 
 // The PeerDaemonManagerClient implementation used in production.
-class PeerDaemonManagerClientImpl : public PeerDaemonManagerClient {
+class PeerDaemonManagerClientImpl : public PeerDaemonManagerClient,
+                                    public dbus::ObjectManager::Interface {
  public:
   PeerDaemonManagerClientImpl();
   ~PeerDaemonManagerClientImpl() override;
 
-  // DBusClient overrides:
+  // DBusClient overrides.
   void Init(dbus::Bus* bus) override;
 
-  // PeerDaemonManagerClient overrides:
+  // PeerDaemonManagerClient overrides.
+  void AddObserver(Observer* observer) override;
+  void RemoveObserver(Observer* observer) override;
+  std::vector<dbus::ObjectPath> GetServices() override;
+  std::vector<dbus::ObjectPath> GetPeers() override;
+  ServiceProperties* GetServiceProperties(
+      const dbus::ObjectPath& object_path) override;
+  PeerProperties* GetPeerProperties(
+      const dbus::ObjectPath& object_path) override;
   void StartMonitoring(
       const std::vector<std::string>& requested_technologies,
       const base::DictionaryValue& options,
@@ -53,55 +68,126 @@ class PeerDaemonManagerClientImpl : public PeerDaemonManagerClient {
                             const VoidDBusMethodCallback& callback) override;
   void Ping(const StringDBusMethodCallback& callback) override;
 
+  // dbus::ObjectManager::Interface overrides.
+  dbus::PropertySet* CreateProperties(
+      dbus::ObjectProxy* object_proxy,
+      const dbus::ObjectPath& object_path,
+      const std::string& interface_name) override;
+  void ObjectAdded(const dbus::ObjectPath& object_path,
+                   const std::string& interface_name) override;
+  void ObjectRemoved(const dbus::ObjectPath& object_path,
+                     const std::string& interface_name) override;
+
  private:
   void OnStringDBusMethod(const StringDBusMethodCallback& callback,
                           dbus::Response* response);
   void OnVoidDBusMethod(const VoidDBusMethodCallback& callback,
                         dbus::Response* response);
+  void OnManagerPropertyChanged(const std::string& property_name);
+  void OnServicePropertyChanged(const dbus::ObjectPath& object_path,
+                                const std::string& property_name);
+  void OnPeerPropertyChanged(const dbus::ObjectPath& object_path,
+                             const std::string& property_name);
+
+  // List of observers interested in event notifications from us.
+  ObserverList<Observer> observers_;
+  dbus::ObjectManager* object_manager_;
 
-  dbus::ObjectProxy* peer_daemon_proxy_;
   base::WeakPtrFactory<PeerDaemonManagerClientImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PeerDaemonManagerClientImpl);
 };
 
 PeerDaemonManagerClientImpl::PeerDaemonManagerClientImpl()
-    : peer_daemon_proxy_(nullptr), weak_ptr_factory_(this) {
+    : object_manager_(nullptr), weak_ptr_factory_(this) {
 }
 
 PeerDaemonManagerClientImpl::~PeerDaemonManagerClientImpl() {
+  if (object_manager_) {
+    object_manager_->UnregisterInterface(peerd::kManagerInterface);
+    object_manager_->UnregisterInterface(peerd::kServiceInterface);
+    object_manager_->UnregisterInterface(peerd::kPeerInterface);
+  }
+}
+
+void PeerDaemonManagerClientImpl::AddObserver(Observer* observer) {
+  DCHECK(observer);
+  observers_.AddObserver(observer);
+}
+
+void PeerDaemonManagerClientImpl::RemoveObserver(Observer* observer) {
+  DCHECK(observer);
+  observers_.RemoveObserver(observer);
+}
+
+std::vector<dbus::ObjectPath> PeerDaemonManagerClientImpl::GetServices() {
+  return object_manager_->GetObjectsWithInterface(peerd::kServiceInterface);
+}
+
+std::vector<dbus::ObjectPath> PeerDaemonManagerClientImpl::GetPeers() {
+  return object_manager_->GetObjectsWithInterface(peerd::kPeerInterface);
+}
+
+PeerDaemonManagerClient::ServiceProperties*
+PeerDaemonManagerClientImpl::GetServiceProperties(
+    const dbus::ObjectPath& object_path) {
+  return static_cast<ServiceProperties*>(
+      object_manager_->GetProperties(object_path, peerd::kServiceInterface));
+}
+
+PeerDaemonManagerClient::PeerProperties*
+PeerDaemonManagerClientImpl::GetPeerProperties(
+    const dbus::ObjectPath& object_path) {
+  return static_cast<PeerProperties*>(
+      object_manager_->GetProperties(object_path, peerd::kPeerInterface));
 }
 
 void PeerDaemonManagerClientImpl::StartMonitoring(
     const std::vector<std::string>& requested_technologies,
     const base::DictionaryValue& options,
     const StringDBusMethodCallback& callback) {
+  dbus::ObjectProxy* object_proxy = object_manager_->GetObjectProxy(
+      dbus::ObjectPath(peerd::kPeerdManagerPath));
+  if (!object_proxy) {
+    base::MessageLoop::current()->PostTask(
+        FROM_HERE,
+        base::Bind(&PeerDaemonManagerClientImpl::OnStringDBusMethod,
+                   weak_ptr_factory_.GetWeakPtr(), callback, nullptr));
+    return;
+  }
+
   dbus::MethodCall method_call(peerd::kManagerInterface,
                                peerd::kStartMonitoringMethod);
   dbus::MessageWriter writer(&method_call);
   writer.AppendArrayOfStrings(requested_technologies);
   dbus::AppendValueData(&writer, options);
-  peer_daemon_proxy_->CallMethod(
-      &method_call,
-      dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
+  object_proxy->CallMethod(
+      &method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
       base::Bind(&PeerDaemonManagerClientImpl::OnStringDBusMethod,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 callback));
+                 weak_ptr_factory_.GetWeakPtr(), callback));
 }
 
 void PeerDaemonManagerClientImpl::StopMonitoring(
     const std::string& monitoring_token,
     const VoidDBusMethodCallback& callback) {
+  dbus::ObjectProxy* object_proxy = object_manager_->GetObjectProxy(
+      dbus::ObjectPath(peerd::kPeerdManagerPath));
+  if (!object_proxy) {
+    base::MessageLoop::current()->PostTask(
+        FROM_HERE,
+        base::Bind(&PeerDaemonManagerClientImpl::OnVoidDBusMethod,
+                   weak_ptr_factory_.GetWeakPtr(), callback, nullptr));
+    return;
+  }
+
   dbus::MethodCall method_call(peerd::kManagerInterface,
                                peerd::kStopMonitoringMethod);
   dbus::MessageWriter writer(&method_call);
   writer.AppendString(monitoring_token);
-  peer_daemon_proxy_->CallMethod(
-      &method_call,
-      dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
+  object_proxy->CallMethod(
+      &method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
       base::Bind(&PeerDaemonManagerClientImpl::OnVoidDBusMethod,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 callback));
+                 weak_ptr_factory_.GetWeakPtr(), callback));
 }
 
 void PeerDaemonManagerClientImpl::ExposeService(
@@ -109,6 +195,16 @@ void PeerDaemonManagerClientImpl::ExposeService(
     const std::map<std::string, std::string>& service_info,
     const base::DictionaryValue& options,
     const StringDBusMethodCallback& callback) {
+  dbus::ObjectProxy* object_proxy = object_manager_->GetObjectProxy(
+      dbus::ObjectPath(peerd::kPeerdManagerPath));
+  if (!object_proxy) {
+    base::MessageLoop::current()->PostTask(
+        FROM_HERE,
+        base::Bind(&PeerDaemonManagerClientImpl::OnStringDBusMethod,
+                   weak_ptr_factory_.GetWeakPtr(), callback, nullptr));
+    return;
+  }
+
   dbus::MethodCall method_call(peerd::kManagerInterface,
                                peerd::kExposeServiceMethod);
   dbus::MessageWriter writer(&method_call);
@@ -126,12 +222,10 @@ void PeerDaemonManagerClientImpl::ExposeService(
   writer.CloseContainer(&array_writer);
 
   dbus::AppendValueData(&writer, options);
-  peer_daemon_proxy_->CallMethod(
-      &method_call,
-      dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
+  object_proxy->CallMethod(
+      &method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
       base::Bind(&PeerDaemonManagerClientImpl::OnStringDBusMethod,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 callback));
+                 weak_ptr_factory_.GetWeakPtr(), callback));
 }
 
 void PeerDaemonManagerClientImpl::RemoveExposedService(
@@ -139,27 +233,95 @@ void PeerDaemonManagerClientImpl::RemoveExposedService(
     const VoidDBusMethodCallback& callback) {
   dbus::MethodCall method_call(peerd::kManagerInterface,
                                peerd::kRemoveExposedServiceMethod);
+  dbus::ObjectProxy* object_proxy = object_manager_->GetObjectProxy(
+      dbus::ObjectPath(peerd::kPeerdManagerPath));
+  if (!object_proxy) {
+    base::MessageLoop::current()->PostTask(
+        FROM_HERE,
+        base::Bind(&PeerDaemonManagerClientImpl::OnVoidDBusMethod,
+                   weak_ptr_factory_.GetWeakPtr(), callback, nullptr));
+    return;
+  }
   dbus::MessageWriter writer(&method_call);
   writer.AppendString(service_token);
-  peer_daemon_proxy_->CallMethod(
-      &method_call,
-      dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
+  object_proxy->CallMethod(
+      &method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
       base::Bind(&PeerDaemonManagerClientImpl::OnVoidDBusMethod,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 callback));
+                 weak_ptr_factory_.GetWeakPtr(), callback));
 }
 
 void PeerDaemonManagerClientImpl::Ping(
     const StringDBusMethodCallback& callback) {
   dbus::MethodCall method_call(peerd::kManagerInterface,
                                peerd::kPingMethod);
+  dbus::ObjectProxy* object_proxy = object_manager_->GetObjectProxy(
+      dbus::ObjectPath(peerd::kPeerdManagerPath));
+  if (!object_proxy) {
+    base::MessageLoop::current()->PostTask(
+        FROM_HERE,
+        base::Bind(&PeerDaemonManagerClientImpl::OnStringDBusMethod,
+                   weak_ptr_factory_.GetWeakPtr(), callback, nullptr));
+    return;
+  }
   dbus::MessageWriter writer(&method_call);
-  peer_daemon_proxy_->CallMethod(
-      &method_call,
-      dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
+  object_proxy->CallMethod(
+      &method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
       base::Bind(&PeerDaemonManagerClientImpl::OnStringDBusMethod,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 callback));
+                 weak_ptr_factory_.GetWeakPtr(), callback));
+}
+
+dbus::PropertySet* PeerDaemonManagerClientImpl::CreateProperties(
+    dbus::ObjectProxy* object_proxy,
+    const dbus::ObjectPath& object_path,
+    const std::string& interface_name) {
+  dbus::PropertySet* properties = nullptr;
+  if (interface_name == peerd::kManagerInterface) {
+    properties = new ManagerProperties(
+        object_proxy,
+        base::Bind(&PeerDaemonManagerClientImpl::OnManagerPropertyChanged,
+                   weak_ptr_factory_.GetWeakPtr()));
+  } else if (interface_name == peerd::kServiceInterface) {
+    properties = new ServiceProperties(
+        object_proxy,
+        base::Bind(&PeerDaemonManagerClientImpl::OnServicePropertyChanged,
+                   weak_ptr_factory_.GetWeakPtr(), object_path));
+  } else if (interface_name == peerd::kPeerInterface) {
+    properties = new PeerProperties(
+        object_proxy,
+        base::Bind(&PeerDaemonManagerClientImpl::OnPeerPropertyChanged,
+                   weak_ptr_factory_.GetWeakPtr(), object_path));
+  } else {
+    NOTREACHED() << "Unhandled interface name " << interface_name;
+  }
+  return properties;
+}
+
+void PeerDaemonManagerClientImpl::ObjectAdded(
+    const dbus::ObjectPath& object_path,
+    const std::string& interface_name) {
+  if (interface_name == peerd::kManagerInterface) {
+    FOR_EACH_OBSERVER(Observer, observers_, ManagerAdded());
+  } else if (interface_name == peerd::kServiceInterface) {
+    FOR_EACH_OBSERVER(Observer, observers_, ServiceAdded(object_path));
+  } else if (interface_name == peerd::kPeerInterface) {
+    FOR_EACH_OBSERVER(Observer, observers_, PeerAdded(object_path));
+  } else {
+    NOTREACHED() << "Unhandled interface name " << interface_name;
+  }
+}
+
+void PeerDaemonManagerClientImpl::ObjectRemoved(
+    const dbus::ObjectPath& object_path,
+    const std::string& interface_name) {
+  if (interface_name == peerd::kManagerInterface) {
+    FOR_EACH_OBSERVER(Observer, observers_, ManagerRemoved());
+  } else if (interface_name == peerd::kServiceInterface) {
+    FOR_EACH_OBSERVER(Observer, observers_, ServiceRemoved(object_path));
+  } else if (interface_name == peerd::kPeerInterface) {
+    FOR_EACH_OBSERVER(Observer, observers_, PeerRemoved(object_path));
+  } else {
+    NOTREACHED() << "Unhandled interface name " << interface_name;
+  }
 }
 
 void PeerDaemonManagerClientImpl::OnStringDBusMethod(
@@ -187,13 +349,68 @@ void PeerDaemonManagerClientImpl::OnVoidDBusMethod(
 }
 
 void PeerDaemonManagerClientImpl::Init(dbus::Bus* bus) {
-  peer_daemon_proxy_ =
-      bus->GetObjectProxy(peerd::kPeerdServiceName,
-                          dbus::ObjectPath(peerd::kPeerdManagerPath));
+  object_manager_ = bus->GetObjectManager(
+      peerd::kPeerdServiceName,
+      dbus::ObjectPath(peerd::kPeerdObjectManagerServicePath));
+  object_manager_->RegisterInterface(peerd::kManagerInterface, this);
+  object_manager_->RegisterInterface(peerd::kServiceInterface, this);
+  object_manager_->RegisterInterface(peerd::kPeerInterface, this);
+}
+
+void PeerDaemonManagerClientImpl::OnManagerPropertyChanged(
+    const std::string& property_name) {
+  FOR_EACH_OBSERVER(Observer, observers_,
+                    ManagerPropertyChanged(property_name));
+}
+
+void PeerDaemonManagerClientImpl::OnServicePropertyChanged(
+    const dbus::ObjectPath& object_path,
+    const std::string& property_name) {
+  FOR_EACH_OBSERVER(Observer, observers_,
+                    ServicePropertyChanged(object_path, property_name));
+}
+
+void PeerDaemonManagerClientImpl::OnPeerPropertyChanged(
+    const dbus::ObjectPath& object_path,
+    const std::string& property_name) {
+  FOR_EACH_OBSERVER(Observer, observers_,
+                    PeerPropertyChanged(object_path, property_name));
 }
 
 }  // namespace
 
+PeerDaemonManagerClient::ManagerProperties::ManagerProperties(
+    dbus::ObjectProxy* object_proxy,
+    const PropertyChangedCallback& callback)
+    : dbus::PropertySet{object_proxy, peerd::kManagerInterface, callback} {
+  RegisterProperty("MonitoredTechnologies", &monitored_technologies_);
+}
+
+PeerDaemonManagerClient::ManagerProperties::~ManagerProperties() {
+}
+
+PeerDaemonManagerClient::ServiceProperties::ServiceProperties(
+    dbus::ObjectProxy* object_proxy,
+    const PropertyChangedCallback& callback)
+    : dbus::PropertySet{object_proxy, peerd::kServiceInterface, callback} {
+  RegisterProperty("ServiceId", &service_id_);
+  RegisterProperty("ServiceInfo", &service_info_);
+  RegisterProperty("IpInfos", &ip_infos_);
+}
+
+PeerDaemonManagerClient::ServiceProperties::~ServiceProperties() {
+}
+
+PeerDaemonManagerClient::PeerProperties::PeerProperties(
+    dbus::ObjectProxy* object_proxy,
+    const PropertyChangedCallback& callback)
+    : dbus::PropertySet{object_proxy, peerd::kPeerInterface, callback} {
+  RegisterProperty("UUID", &uuid_);
+  RegisterProperty("LastSeen", &last_seen_);
+}
+
+PeerDaemonManagerClient::PeerProperties::~PeerProperties() {
+}
 
 PeerDaemonManagerClient::PeerDaemonManagerClient() {
 }
diff --git a/chromeos/dbus/peer_daemon_manager_client.h b/chromeos/dbus/peer_daemon_manager_client.h
index a7cacb3..a3cad81 100644
--- a/chromeos/dbus/peer_daemon_manager_client.h
+++ b/chromeos/dbus/peer_daemon_manager_client.h
@@ -7,6 +7,7 @@
 
 #include <map>
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "base/macros.h"
@@ -14,6 +15,7 @@
 #include "chromeos/chromeos_export.h"
 #include "chromeos/dbus/dbus_client.h"
 #include "chromeos/dbus/dbus_method_call_status.h"
+#include "dbus/property.h"
 
 namespace chromeos {
 
@@ -22,12 +24,130 @@ namespace chromeos {
 // initializes the DBusThreadManager instance.
 class CHROMEOS_EXPORT PeerDaemonManagerClient : public DBusClient {
  public:
+  class ManagerProperties : public dbus::PropertySet {
+   public:
+    ManagerProperties(dbus::ObjectProxy* object_proxy,
+                      const PropertyChangedCallback& callback);
+    ~ManagerProperties() override;
+
+    const std::vector<std::string>& monitored_technologies() const {
+      return monitored_technologies_.value();
+    }
+
+   private:
+    dbus::Property<std::vector<std::string>> monitored_technologies_;
+
+    DISALLOW_COPY_AND_ASSIGN(ManagerProperties);
+  };
+
+  class ServiceProperties : public dbus::PropertySet {
+   public:
+    ServiceProperties(dbus::ObjectProxy* object_proxy,
+                      const PropertyChangedCallback& callback);
+    ~ServiceProperties() override;
+
+    const std::string& service_id() const { return service_id_.value(); }
+    const std::map<std::string, std::string>& service_info() const {
+      return service_info_.value();
+    }
+    const std::vector<std::pair<std::vector<uint8_t>, uint16_t>>& ip_infos()
+        const {
+      return ip_infos_.value();
+    }
+
+   private:
+    dbus::Property<std::string> service_id_;
+    dbus::Property<std::map<std::string, std::string>> service_info_;
+    dbus::Property<std::vector<std::pair<std::vector<uint8_t>, uint16_t>>>
+        ip_infos_;
+
+    DISALLOW_COPY_AND_ASSIGN(ServiceProperties);
+  };
+
+  class PeerProperties : public dbus::PropertySet {
+   public:
+    PeerProperties(dbus::ObjectProxy* object_proxy,
+                   const PropertyChangedCallback& callback);
+    ~PeerProperties() override;
+
+    const std::string& uuid() const { return uuid_.value(); }
+    uint64_t last_seen() const { return last_seen_.value(); }
+
+   private:
+    dbus::Property<std::string> uuid_;
+    dbus::Property<uint64_t> last_seen_;
+
+    DISALLOW_COPY_AND_ASSIGN(PeerProperties);
+  };
+
+  // Interface for observing changes from a leadership daemon.
+  class Observer {
+   public:
+    virtual ~Observer() {}
+
+    // Called when the peer daemon manager is added.
+    virtual void ManagerAdded() {}
+
+    // Called when the peer daemon manager is removed; perhaps on a process
+    // crash of the peer daemon.
+    virtual void ManagerRemoved() {}
+
+    // Called when the manager changes a property value.
+    virtual void ManagerPropertyChanged(const std::string& property_name) {}
+
+    // Called when the service with object path |object_path| is added to the
+    // system.
+    virtual void ServiceAdded(const dbus::ObjectPath& object_path) {}
+
+    // Called when the service with object path |object_path| is removed from
+    // the system.
+    virtual void ServiceRemoved(const dbus::ObjectPath& object_path) {}
+
+    // Called when the service with object path |object_path| changes a
+    // property value.
+    virtual void ServicePropertyChanged(const dbus::ObjectPath& object_path,
+                                        const std::string& property_name) {}
+
+    // Called when the peer with object path |object_path| is added to the
+    // system.
+    virtual void PeerAdded(const dbus::ObjectPath& object_path) {}
+
+    // Called when the peer with object path |object_path| is removed from
+    // the system.
+    virtual void PeerRemoved(const dbus::ObjectPath& object_path) {}
+
+    // Called when the peer with object path |object_path| changes a
+    // property value.
+    virtual void PeerPropertyChanged(const dbus::ObjectPath& object_path,
+                                     const std::string& property_name) {}
+  };
+
   ~PeerDaemonManagerClient() override;
 
   // Factory function, creates a new instance which is owned by the caller.
   // For normal usage, access the singleton via DBusThreadManager::Get().
   static PeerDaemonManagerClient* Create();
 
+  // Adds and removes observers for events on all peer events.
+  virtual void AddObserver(Observer* observer) = 0;
+  virtual void RemoveObserver(Observer* observer) = 0;
+
+  // Retrieves a list of all the services.
+  virtual std::vector<dbus::ObjectPath> GetServices() = 0;
+
+  // Retrieves a list of all the peers.
+  virtual std::vector<dbus::ObjectPath> GetPeers() = 0;
+
+  // Obtains the properties for the service with object path |object_path|,
+  // any values should be copied if needed.
+  virtual ServiceProperties* GetServiceProperties(
+      const dbus::ObjectPath& object_path) = 0;
+
+  // Obtains the properties for the peer with object path |object_path|,
+  // any values should be copied if needed.
+  virtual PeerProperties* GetPeerProperties(
+      const dbus::ObjectPath& object_path) = 0;
+
   // Calls StartMonitoring method.
   // |callback| is called with its |call_status| argument set to
   // DBUS_METHOD_CALL_SUCCESS if the method call succeeds. Otherwise,