[ONOS-3648] Implement REST API for collecting system metrics

- Implement REST API for gathering system metrics
- Add unit test for REST API
- Add swagger doc for REST API

Change-Id: Iedd21a5f6ed14d595e4d35c1fa08270b48a5031e
diff --git a/apps/cpman/src/main/java/org/onosproject/cpman/ControlPlaneManager.java b/apps/cpman/src/main/java/org/onosproject/cpman/ControlPlaneManager.java
index 3305297..941cc0f 100644
--- a/apps/cpman/src/main/java/org/onosproject/cpman/ControlPlaneManager.java
+++ b/apps/cpman/src/main/java/org/onosproject/cpman/ControlPlaneManager.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2016 Open Networking Laboratory
+ * Copyright 2016 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.
@@ -16,117 +16,47 @@
 package org.onosproject.cpman;
 
 import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Deactivate;
 import org.apache.felix.scr.annotations.Modified;
-import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Reference;
 import org.apache.felix.scr.annotations.ReferenceCardinality;
-import org.onlab.metrics.MetricsService;
 import org.onosproject.core.ApplicationId;
 import org.onosproject.core.CoreService;
 import org.onosproject.net.device.DeviceService;
 import org.slf4j.Logger;
-
-import java.util.HashSet;
-import java.util.Optional;
-import java.util.Set;
-
-import static org.slf4j.LoggerFactory.getLogger;
+import org.slf4j.LoggerFactory;
 
 /**
- * Control plane management application.
+ * Skeletal ONOS application component.
  */
 @Component(immediate = true)
 public class ControlPlaneManager {
 
-    private final Logger log = getLogger(getClass());
-    private Set<ControlMetricsObserver> controlMetricsObservers = new HashSet<>();
-    private ControlMetricsObserver cpObserver;
-
-    private ApplicationId appId;
-
-    private ControlMetricsFactory cmf;
-
-    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
-    protected DeviceService deviceService;
+    private final Logger log = LoggerFactory.getLogger(getClass());
 
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
     protected CoreService coreService;
 
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
-    protected MetricsService metricsService;
+    protected DeviceService deviceService;
+
+    private ApplicationId appId;
 
     @Activate
-    public void activate() {
+    protected void activate() {
         appId = coreService.registerApplication("org.onosproject.cpman");
-
-        cmf = ControlMetricsFactory.getInstance(metricsService, deviceService);
-        // currently disable monitoring by default
-        // cmf.startMonitor();
-
-        registerObserver();
-
+        deviceService.getAvailableDevices();
         log.info("Started");
     }
 
     @Deactivate
-    public void deactivate() {
-        unregisterObserver();
-        cmf.stopMonitor();
+    protected void deactivate() {
         log.info("Stopped");
     }
 
     @Modified
-    public void modified() {
+    protected void modified() {
     }
 
-    private void registerObserver() {
-        cpObserver = new DefaultControlMetricsObserver();
-        this.addControlMetricsObserver(cpObserver);
-    }
-
-    private void unregisterObserver() {
-        this.removeControlMetricsObserver(cpObserver);
-    }
-
-    private void executeMonitorTask() {
-
-        // TODO: execute monitoring task with 1 minute period
-        if (cmf.isMonitor()) {
-            controlMetricsObservers.forEach(observer -> {
-
-                // only OpenFlow messages are spontaneously monitored with
-                // 1 minute period. Other system metrics will be pushed from
-                // external monitoring agent through REST API
-
-                // feed the control message stats
-                cmf.getDeviceIds().forEach(v -> {
-                    observer.feedMetrics(cmf.inboundPacket(v), Optional.of(v));
-                    observer.feedMetrics(cmf.outboundPacket(v), Optional.of(v));
-                    observer.feedMetrics(cmf.flowmodPacket(v), Optional.of(v));
-                    observer.feedMetrics(cmf.flowrmvPacket(v), Optional.of(v));
-                    observer.feedMetrics(cmf.requestPacket(v), Optional.of(v));
-                    observer.feedMetrics(cmf.replyPacket(v), Optional.of(v));
-                });
-            });
-        }
-    }
-
-    /**
-     * Adds a new control metrics observer.
-     *
-     * @param cmObserver control metric observer instance
-     */
-    public void addControlMetricsObserver(ControlMetricsObserver cmObserver) {
-        controlMetricsObservers.add(cmObserver);
-    }
-
-    /**
-     * Removes an existing control metrics observer.
-     *
-     * @param cmObserver control metric observer instance
-     */
-    public void removeControlMetricsObserver(ControlMetricsObserver cmObserver) {
-        controlMetricsObservers.remove(cmObserver);
-    }
 }