Consolidating null providers and making them fully configurable and integrated with the ConfigProvider to allow arbitrary topologies.

Change-Id: I899e27a9771af4013a3ce6da7f683a4927ffb438
diff --git a/providers/null/src/main/java/org/onosproject/provider/nil/cli/NullControlCommand.java b/providers/null/src/main/java/org/onosproject/provider/nil/cli/NullControlCommand.java
new file mode 100644
index 0000000..261f46d
--- /dev/null
+++ b/providers/null/src/main/java/org/onosproject/provider/nil/cli/NullControlCommand.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.provider.nil.cli;
+
+import org.apache.karaf.shell.commands.Argument;
+import org.apache.karaf.shell.commands.Command;
+import org.onosproject.cfg.ComponentConfigService;
+import org.onosproject.cli.AbstractShellCommand;
+import org.onosproject.provider.nil.NullProviders;
+
+import static org.onosproject.cli.StartStopCompleter.START;
+
+/**
+ * Starts or stops topology simulation.
+ */
+@Command(scope = "onos", name = "null-simulation",
+        description = "Starts or stops topology simulation")
+public class NullControlCommand extends AbstractShellCommand {
+
+    @Argument(index = 0, name = "cmd", description = "Control command: start/stop",
+            required = true, multiValued = false)
+    String cmd = null;
+
+    @Argument(index = 1, name = "topoShape",
+            description = "Topology shape: e.g. configured, linear, reroute, centipede, tree, spineleaf, mesh",
+            required = false, multiValued = false)
+    String topoShape = null;
+
+    @Override
+    protected void execute() {
+        ComponentConfigService service = get(ComponentConfigService.class);
+        if (topoShape != null) {
+            service.setProperty(NullProviders.class.getName(), "topoShape", topoShape);
+        }
+        service.setProperty(NullProviders.class.getName(), "enabled",
+                            cmd.equals(START) ? "true" : "false");
+    }
+
+}