oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/Layer.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.skywalking.oap.server.core.analysis;

import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import org.apache.skywalking.oap.server.core.UnexpectedException;

/**
 * Layer represents an abstract framework in computer science, such as Operating System(OS_LINUX layer), Kubernetes(k8s
 * layer). This kind of layer would be owners of different services detected from different technology.
 */
public enum Layer {
    /**
     * Default Layer if the layer is not defined
     */
    UNDEFINED(0, false),

    /**
     * Envoy Access Log Service
     */
    MESH(1, true),

    /**
     * Agent-installed Service
     */
    GENERAL(2, true),

    /**
     * Linux Machine
     */
    OS_LINUX(3, true),

    /**
     * Kubernetes cluster
     */
    K8S(4, true),

    /**
     * Function as a Service
     */
    FAAS(5, true),

    /**
     * Mesh control plane, eg. Istio control plane
     */
    MESH_CP(6, true),

    /**
     * Mesh data plane, eg. Envoy
     */
    MESH_DP(7, true),

    /**
     * Telemetry from real database
     */
    DATABASE(8, true),

    /**
     * Cache service eg. ehcache, guava-cache, memcache
     */
    CACHE(9, true),

    /**
     * Telemetry from the Browser eg. Apache SkyWalking Client JS
     */
    BROWSER(10, true),

    /**
     * Self Observability of OAP
     */
    SO11Y_OAP(11, true),

    /**
     * Self Observability of Satellite
     */
    SO11Y_SATELLITE(12, true),

    /**
     * Telemetry from the real MQ
     */
    MQ(13, true),

    /**
     * Database conjectured by client side plugin
     */
    VIRTUAL_DATABASE(14, false),

    /**
     * MQ conjectured by client side plugin
     */
    VIRTUAL_MQ(15, false),

    /**
     * The uninstrumented gateways configured in OAP
     */
    VIRTUAL_GATEWAY(16, false),

    /**
     * Kubernetes service
     */
    K8S_SERVICE(17, true),

    /**
     * MySQL Server, also known as mysqld, is a single multithreaded program that does most of the work in a MySQL installation. 
     */
    MYSQL(18, true),

    /**
     * Cache conjectured by client side plugin(eg. skywalking-java -> JedisPlugin LettucePlugin)
     */
    VIRTUAL_CACHE(19, false);

    private final int value;
    /**
     * The `normal` status represents this service is detected by an agent. The `un-normal` service is conjectured by
     * telemetry data collected from agents on/in the `normal` service.
     */
    private final boolean isNormal;
    private static final Map<Integer, Layer> DICTIONARY = new HashMap<>();
    private static final Map<String, Layer> DICTIONARY_NAME = new HashMap<>();

    static {
        Arrays.stream(Layer.values()).forEach(l -> {
            DICTIONARY.put(l.value, l);
            DICTIONARY_NAME.put(l.name(), l);
        });
    }

    Layer(int value, boolean isNormal) {
        this.value = value;
        this.isNormal = isNormal;
    }

    public int value() {
        return value;
    }

    public static Layer valueOf(int value) {
        Layer layer = DICTIONARY.get(value);
        if (layer == null) {
            throw new UnexpectedException("Unknown Layer value");
        }
        return layer;
    }

    public static Layer nameOf(String name) {
        Layer layer = DICTIONARY_NAME.get(name);
        if (layer == null) {
            throw new UnexpectedException("Unknown Layer name");
        }
        return layer;
    }

    public boolean isNormal() {
        return isNormal;
    }
}