[ONOS-5473] Defining VirtualFlowRuleProvider interface.
Changes
1. Defined provider/registry structure for virtual providers
2. Added VirtualFlowRuleProvider
3. Added VirtualFlowRuleProivderService
4. Added VirtaulFlowRuleProviderRegistry
Change-Id: I3aa0eaee050177d06cade88c63df13f165ca5cf2
diff --git a/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/provider/VirtualProviderRegistry.java b/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/provider/VirtualProviderRegistry.java
new file mode 100644
index 0000000..8240139
--- /dev/null
+++ b/incubator/api/src/main/java/org/onosproject/incubator/net/virtual/provider/VirtualProviderRegistry.java
@@ -0,0 +1,56 @@
+/*
+ * Copyright 2016-present 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.incubator.net.virtual.provider;
+
+import java.util.Set;
+
+/** Registry for tracking information virtual providers with the core.
+ * @param <P> type of the information virtual provider
+ * @param <S> type of the provider virtual service
+ */
+
+public interface VirtualProviderRegistry<P extends VirtualProvider,
+ S extends VirtualProviderService<P>> {
+
+ /**
+ * Registers the supplied virtual provider with the virtual core.
+ *
+ * @param provider virtual provider to be registered
+ * @return service for injecting information into core
+ * @throws java.lang.IllegalArgumentException if the provider is registered already
+ */
+ S register(P provider);
+
+ /**
+ * Unregisters the supplied virtual provider.
+ * As a result the previously issued virtual provider service
+ * will be invalidated and any subsequent invocations
+ * of its methods may throw {@link java.lang.IllegalStateException}.
+ * Unregistering a virtual provider that has not been previously registered
+ * result in a no-op.
+ *
+ * @param provider provider to be unregistered
+ */
+ void unregister(P provider);
+
+ /**
+ * Returns a set of currently registered virtual providers.
+ *
+ * @return set of virtual providers
+ */
+ Set<P> getProviders();
+}