D-Bus: added Server.GetCapabilities and Server.GetVersions (BMC #3563)

We are about to extend the D-Bus API. Clients need some way of determining
whether the new features are available. A strict numbering of the API is
inflexible, so let's use "capability" strings instead. Also add flexible
version querying, for debugging.

src/dbus/interfaces/syncevo-server-full.xml

@@ -44,6 +44,74 @@
       </doc:para>
     </doc:doc>
 
+    <method name="GetCapabilities">
+      <doc:doc>
+        <doc:description>
+          <doc:para>
+            Describes which features are implemented by the server. If the method itself
+            is unavailable, then the features correspond to SyncEvolution 1.0. The following
+            capabilities are currently defined:
+            <doc:list>
+              <doc:item><doc:term>ConfigChanged</doc:term>
+                <doc:definition>Server.ConfigChange
+                  signal available; if not, reread config after each
+                  session
+                </doc:definition>
+              </doc:item>
+             
+              <doc:item><doc:term>GetConfigName</doc:term>
+                <doc:definition>Session.GetConfigName()
+                  implemented
+                </doc:definition>
+              </doc:item>
+             
+              <doc:item><doc:term>Notifications</doc:term>
+                <doc:definition>Server.DisableNotifications()
+                  and Server.EnableNotifications() implemented
+                </doc:definition>
+              </doc:item>
+             
+              <doc:item><doc:term>Version</doc:term>
+                <doc:definition>Server.GetVersion()
+                  implemented; note that this is not meant to be used to determine supported
+                  features
+                </doc:definition>
+              </doc:item>
+             
+              <doc:item><doc:term>SessionFlags</doc:term>
+                <doc:definition>Server.StartSessionWithFlags()
+                  and Session.GetFlags() are implemented
+                </doc:definition>
+              </doc:item>
+            </doc:list>
+          </doc:para>
+        </doc:description>
+      </doc:doc>
+      <arg type="a{s}" name="capabilities" direction="out">
+        <doc:doc><doc:summary>
+          set of supported capabilities
+        </doc:summary></doc:doc>
+      </arg>
+    </method>
+
+    <method name="GetVersions">
+      <doc:doc>
+        <doc:description>
+          <doc:para>
+            Returns information about server side implementations.
+          </doc:para>
+        </doc:description>
+      </doc:doc>
+      <arg type="a{ss}" name="info" direction="out">
+        <doc:doc><doc:summary>
+            "version" - main SyncEvolution release name (usually a number,
+sometimes also a beta or alpha suffix),
+            "system" - some plain text information about system libraries,
+            "backends" - available backend libraries
+        </doc:summary></doc:doc>
+      </arg>
+    </method>  
+
     <method name="Attach">
       <doc:doc>
         <doc:description>

src/syncevo-dbus-server.cpp

@@ -1024,6 +1024,12 @@ class DBusServer : public DBusObjectHelper,
      */
     void clientGone(Client *c);
 
+    /** Server.GetCapabilities() */
+    vector<string> getCapabilities();
+
+    /** Server.GetVersions() */
+    StringMap getVersions();
+
     /** Server.Attach() */
     void attachClient(const Caller_t &caller,
                       const boost::shared_ptr<Watch> &watch);
@@ -4609,6 +4615,31 @@ std::string DBusServer::getNextSession()
     return StringPrintf("%u%u", rand(), m_lastSession);
 }
 
+vector<string> DBusServer::getCapabilities()
+{
+    // Note that this is tested by test-dbus.py in
+    // TestDBusServer.testCapabilities, update the test when adding
+    // capabilities.
+    vector<string> capabilities;
+
+    // capabilities.push_back("ConfigChanged");
+    // capabilities.push_back("GetConfigName");
+    // capabilities.push_back("Notifications");
+    capabilities.push_back("Version");
+    // capabilities.push_back("SessionFlags");
+    return capabilities;
+}
+
+StringMap DBusServer::getVersions()
+{
+    StringMap versions;
+
+    versions["version"] = VERSION;
+    versions["system"] = EDSAbiWrapperInfo();
+    versions["backends"] = SyncSource::backendsInfo();
+    return versions;
+}
+
 void DBusServer::attachClient(const Caller_t &caller,
                               const boost::shared_ptr<Watch> &watch)
 {
@@ -4751,6 +4782,8 @@ DBusServer::DBusServer(GMainLoop *loop, const DBusConnectionPtr &conn, int durat
     struct timeval tv;
     gettimeofday(&tv, NULL);
     srand(tv.tv_usec);
+    add(this, &DBusServer::getCapabilities, "GetCapabilities");
+    add(this, &DBusServer::getVersions, "GetVersions");
     add(this, &DBusServer::attachClient, "Attach");
     add(this, &DBusServer::detachClient, "Detach");
     add(this, &DBusServer::connect, "Connect");

test/test-dbus.py

@@ -532,6 +532,17 @@ class TestDBusServer(unittest.TestCase, DBusUtil):
     def run(self, result):
         self.runTest(result)
 
+    def testCapabilities(self):
+        """check the Server.GetCapabilities() call"""
+        self.failUnlessEqual(self.server.GetCapabilities(), ['Version'])
+
+    def testVersions(self):
+        """check the Server.GetVersions() call"""
+        versions = self.server.GetVersions()
+        self.failIfEqual(versions["version"], "")
+        self.failIfEqual(versions["system"], None)
+        self.failIfEqual(versions["backends"], None)
+
     def testGetConfigsEmpty(self):
         """GetConfigs() with no configurations available"""
         configs = self.server.GetConfigs(False, utf8_strings=True)