api/src/main/java/org/apache/brooklyn/api/sensor/Sensor.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.brooklyn.api.sensor;

import java.io.Serializable;
import java.util.List;

import org.apache.brooklyn.api.entity.Entity;

import com.google.common.reflect.TypeToken;

/**
 * The interface implemented by concrete sensors.
 * 
 * A sensor is a container for a piece of data of a particular type, and exists in a hierarchical namespace.
 * The name of the sensor is described as a set of tokens separated by dots.
 * 
 * @see SensorEvent
 */
public interface Sensor<T> extends Serializable {
    /**
     * Returns the Java {@link Class} for the sensor data.
     * <p>
     * This returns a "super" of T only in the case where T is generified, 
     * and in such cases it returns the Class instance for the unadorned T ---
     * i.e. for List&lt;String&gt; this returns Class<List> ---
     * this is of course because there is no actual Class&lt;List&lt;String&gt;&gt; instance.
     */
    Class<? super T> getType();
    
    /**
     * Returns the Guava TypeToken (including generics info)
     */
    TypeToken<T> getTypeToken();
    
    /**
     * Returns the type of the sensor data, as a {@link String} representation of the class name.
     * (Useful for contexts where Type is not accessible.)
     */
    String getTypeName();

    /**
     * Returns the name of the sensor, in a dot-separated namespace.
     */
    String getName();
    
    /**
     * Returns the constituent parts of the sensor name as a {@link List}.
     */
    List<String> getNameParts();
 
    /**
     * Returns the description of the sensor, for display.
     */
    String getDescription();
 
    /**
     * Create a new {@link SensorEvent} object for a specific {@link Entity} and data point.
     */
    SensorEvent<T> newEvent(Entity entity, T value);
}