Add flow rule interface, builder, admin manager for statistics.

 Add API for removing flow rule.

Change-Id: If642a2ec8546f73da7234197ad19a97b6a1dc9da
diff --git a/apps/openstacktelemetry/app/src/main/java/org/onosproject/openstacktelemetry/codec/StatsFlowRuleJsonCodec.java b/apps/openstacktelemetry/app/src/main/java/org/onosproject/openstacktelemetry/codec/StatsFlowRuleJsonCodec.java
new file mode 100644
index 0000000..8fc8143
--- /dev/null
+++ b/apps/openstacktelemetry/app/src/main/java/org/onosproject/openstacktelemetry/codec/StatsFlowRuleJsonCodec.java
@@ -0,0 +1,103 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * 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.openstacktelemetry.codec;
+
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.apache.commons.lang3.exception.ExceptionUtils;
+import org.onlab.packet.IPv4;
+import org.onlab.packet.TpPort;
+import org.onosproject.codec.CodecContext;
+import org.onosproject.codec.JsonCodec;
+import org.onosproject.openstacktelemetry.api.StatsFlowRule;
+import org.onosproject.openstacktelemetry.impl.DefaultStatsFlowRule;
+import org.slf4j.Logger;
+
+import org.onlab.packet.IpPrefix;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static org.slf4j.LoggerFactory.getLogger;
+
+public class StatsFlowRuleJsonCodec extends JsonCodec<StatsFlowRule> {
+
+    private final Logger log = getLogger(getClass());
+
+    public static final String SRC_IP_PREFIX = "srcIpPrefix";
+    public static final String DST_IP_PREFIX = "dstIpPrefix";
+    public static final String IP_PROTOCOL   = "ipProtocol";
+    public static final String SRC_TP_PORT   = "srcTpPort";
+    public static final String DST_TP_PORT   = "dstTpPort";
+
+    public ObjectNode encode(StatsFlowRule flowRule, CodecContext context) {
+        checkNotNull(flowRule, "FlowInfo cannot be null");
+        ObjectNode result = context.mapper().createObjectNode()
+                            .put(SRC_IP_PREFIX, flowRule.srcIpPrefix().toString())
+                            .put(DST_IP_PREFIX, flowRule.dstIpPrefix().toString())
+                            .put(IP_PROTOCOL, flowRule.ipProtocol())
+                            .put(SRC_TP_PORT, flowRule.srcTpPort().toString())
+                            .put(DST_TP_PORT, flowRule.dstTpPort().toString());
+        return result;
+    }
+
+    @Override
+    public StatsFlowRule decode(ObjectNode json, CodecContext context) {
+        if (json == null || !json.isObject()) {
+            return null;
+        }
+        try {
+            String srcIpPrefix = json.get(SRC_IP_PREFIX).asText();
+            String dstIpPrefix = json.get(DST_IP_PREFIX).asText();
+            String tmpIpProtocol = new String("");
+            int srcTpPort  = 0;
+            int dstTpPort  = 0;
+
+            DefaultStatsFlowRule.Builder flowRuleBuilder;
+
+            byte ipProtocol = 0;
+            if (json.get(IP_PROTOCOL) == null) {
+                log.info("ipProtocol: null");
+                flowRuleBuilder = DefaultStatsFlowRule.builder()
+                        .srcIpPrefix(IpPrefix.valueOf(srcIpPrefix))
+                        .dstIpPrefix(IpPrefix.valueOf(dstIpPrefix));
+            } else {
+                tmpIpProtocol = json.get(IP_PROTOCOL).asText().toUpperCase();
+                srcTpPort     = json.get(SRC_TP_PORT).asInt();
+                dstTpPort     = json.get(DST_TP_PORT).asInt();
+                if (tmpIpProtocol.equals("TCP")) {
+                    ipProtocol = IPv4.PROTOCOL_TCP;
+                } else if (tmpIpProtocol.equals("UDP")) {
+                    ipProtocol = IPv4.PROTOCOL_UDP;
+                } else {
+                    ipProtocol = 0;
+                }
+
+                flowRuleBuilder = DefaultStatsFlowRule.builder()
+                        .srcIpPrefix(IpPrefix.valueOf(srcIpPrefix))
+                        .dstIpPrefix(IpPrefix.valueOf(dstIpPrefix))
+                        .ipProtocol(ipProtocol)
+                        .srcTpPort(TpPort.tpPort(srcTpPort))
+                        .dstTpPort(TpPort.tpPort(dstTpPort));
+            }
+
+            log.debug("StatsFlowRule after building from JSON:\n{}",
+                     flowRuleBuilder.build().toString());
+
+            return flowRuleBuilder.build();
+        } catch (Exception ex) {
+            log.error("Exception Stack:\n{}", ExceptionUtils.getStackTrace(ex));
+        }
+        return null;
+    }
+}