Adding skeletal REST API for DHCP app.

Change-Id: I9c3ceed5f12f8b293287562bcb1dd7699b676376
diff --git a/onos-app-dhcpserver/src/main/java/org/onosproject/dhcpserver/rest/DHCPWebResource.java b/onos-app-dhcpserver/src/main/java/org/onosproject/dhcpserver/rest/DHCPWebResource.java
new file mode 100644
index 0000000..639dbf0
--- /dev/null
+++ b/onos-app-dhcpserver/src/main/java/org/onosproject/dhcpserver/rest/DHCPWebResource.java
@@ -0,0 +1,75 @@
+/*
+ * 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.dhcpserver.rest;
+
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.onosproject.dhcpserver.DHCPService;
+import org.onosproject.rest.AbstractWebResource;
+
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Response;
+
+/**
+ * Manage DHCP address assignments.
+ */
+@Path("/")
+public class DHCPWebResource extends AbstractWebResource {
+
+    /**
+     * Get DHCP server configuration data.
+     * Shows lease, renewal and rebinding times in seconds.
+     *
+     * @return 200 OK
+     */
+    @GET
+    @Path("config")
+    public Response getConfigs() {
+        DHCPService service = get(DHCPService.class);
+        ObjectNode node = mapper().createObjectNode()
+                .put("leaseTime", service.getLeaseTime())
+                .put("renewalTime", service.getRenewalTime())
+                .put("rebindingTime", service.getRebindingTime());
+        return ok(node.toString()).build();
+    }
+
+
+    // POST should accept a single mac/ip binding with
+    /*
+        {
+            "mac": "00:......00",
+            "ip": "12.34.56.78"
+        }
+     */
+
+    //    @POST
+    //    @Path("mappings")
+
+
+
+    // GET all mappings should look like this:
+    /*
+        {
+            "mappings": [
+                {
+                    "mac": "00:......00",
+                    "ip": "12.34.56.78",
+                    ...
+                }
+            ]
+        }
+     */
+}