Merge pull request #187 from eclipse-thingweb/synchronous-start

Introduce `startClientFactories` method to Servient

lib/src/core/implementation/servient.dart

@@ -52,6 +52,15 @@ abstract class Servient {
   /// discovering Things.
   Future<scripting_api.WoT> start();
 
+  /// Synchronously starts this [Servient] and returns a [scripting_api.WoT]
+  /// runtime object.
+  ///
+  /// In contrast to the [start] method, this method only initializes the
+  /// [ProtocolClientFactory]s and not the [ProtocolServer]s registered with
+  /// this [Servient].
+  /// This has the advantage that it is not necessary to return a [Future].
+  scripting_api.WoT startClientFactories();
+
   /// Adds a new [clientFactory] to this [Servient].
   void addClientFactory(ProtocolClientFactory clientFactory);
 
@@ -90,19 +99,29 @@ class InternalServient implements Servient {
   final ContentSerdes contentSerdes;
 
   @override
-  Future<WoT> start() async {
-    final serverStatuses = _servers
-        .map((server) => server.start(_serverSecurityCallback))
-        .toList(growable: false);
-
+  WoT startClientFactories() {
     for (final clientFactory in _clientFactories.values) {
       clientFactory.init();
     }
 
-    await Future.wait(serverStatuses);
     return WoT(this);
   }
 
+  Future<void> _startServers() async {
+    final serverStatuses = _servers
+        .map((server) => server.start(_serverSecurityCallback))
+        .toList(growable: false);
+
+    await Future.wait(serverStatuses);
+  }
+
+  @override
+  Future<WoT> start() async {
+    await _startServers();
+
+    return startClientFactories();
+  }
+
   @override
   Future<void> shutdown() async {
     for (final clientFactory in _clientFactories.values) {