Introduce Pi Register model to PI Framework

Change-Id: I7fae87d5b5ed5fff34b3addfc148cee6fc98137c
diff --git a/core/api/src/main/java/org/onosproject/net/behaviour/PiRegisterProgrammable.java b/core/api/src/main/java/org/onosproject/net/behaviour/PiRegisterProgrammable.java
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+++ b/core/api/src/main/java/org/onosproject/net/behaviour/PiRegisterProgrammable.java
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+/*
+ * 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.net.behaviour;
+
+import com.google.common.annotations.Beta;
+import org.onosproject.net.driver.HandlerBehaviour;
+import org.onosproject.net.pi.model.PiRegisterId;
+import org.onosproject.net.pi.runtime.PiRegisterCell;
+import org.onosproject.net.pi.runtime.PiRegisterCellId;
+
+import java.util.Collection;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * Protocol-independent register programmable device behaviour.
+ */
+@Beta
+public interface PiRegisterProgrammable extends HandlerBehaviour {
+
+    /**
+     * Write a register cell of this device.
+     *
+     * @param entry register entry
+     * @return Completable future with result of the operation
+     */
+    CompletableFuture<Boolean> writeRegisterCell(PiRegisterCell entry);
+
+    /**
+     * Gets the register cell given the register cell ID from the device.
+     *
+     * @param cellId the register cell Id
+     * @return completable future with the register cell
+     */
+    CompletableFuture<PiRegisterCell> readRegisterCell(PiRegisterCellId cellId);
+
+    /**
+     * Gets the register cells given the collection of cellIds from the device.
+     *
+     * @param cellIds the collection of register cell Id
+     * @return completable future with the collection of register cells
+     */
+    CompletableFuture<Collection<PiRegisterCell>> readRegisterCells(Set<PiRegisterCellId> cellIds);
+
+    /**
+     * Gets all of the register cells given register ID from the device.
+     * @param registerId the identifier of register
+     * @return completable future with the collection of register cells
+     */
+    CompletableFuture<Collection<PiRegisterCell>> readRegisterCells(PiRegisterId registerId);
+
+    /**
+     * Gets all of the register cells from the device.
+     *
+     * @return completable future with the collection of register cells
+     */
+    CompletableFuture<Collection<PiRegisterCell>> readAllRegisterCells();
+}
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