content: /*
   * Copyright 1999-2020 Alibaba Group Holding Ltd.
   *
   * 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 com.alibaba.nacos.core.remote.grpc.negotiator;
  
  import com.alibaba.nacos.common.utils.Pair;
  import com.alibaba.nacos.core.remote.grpc.negotiator.tls.SdkDefaultTlsProtocolNegotiatorBuilder;
  
  /**
   * Manages ProtocolNegotiatorBuilders for the interaction between Nacos and SDK. Provides a singleton instance of
   * ProtocolNegotiatorBuilder configured for this interaction. Defaults to TLS protocol negotiation but can be overridden
   * via system properties.
   *
   *
   * <p>Property key for configuring the ProtocolNegotiator type for Nacos and SDK interaction.
   *
   * @author stone-98
   * @date 2024/2/21
   */
  public class SdkProtocolNegotiatorBuilderSingleton extends AbstractProtocolNegotiatorBuilderSingleton {
      
      /**
       * Property key to retrieve the type of ProtocolNegotiatorBuilder.
       */
      public static final String TYPE_PROPERTY_KEY = "nacos.remote.server.rpc.protocol.negotiator.type";
      
      /**
       * Singleton instance of SdkProtocolNegotiatorBuilderSingleton.
       */
      private static final SdkProtocolNegotiatorBuilderSingleton SINGLETON = new SdkProtocolNegotiatorBuilderSingleton();
      
      /**
       * Constructs a new instance of SdkProtocolNegotiatorBuilderSingleton. Sets up the type property key for
       * ProtocolNegotiatorBuilder.
       */
      public SdkProtocolNegotiatorBuilderSingleton() {
          super(TYPE_PROPERTY_KEY);
      }
      
      /**
       * Retrieves the singleton instance of SdkProtocolNegotiatorBuilderSingleton.
       *
       * @return the singleton instance
       */
      public static AbstractProtocolNegotiatorBuilderSingleton getSingleton() {
          return SINGLETON;
      }
      
      /**
       * Provides the default ProtocolNegotiatorBuilder pair.
       *
       * @return a Pair containing the default type and builder instance
       */
      @Override
      protected Pair<String, ProtocolNegotiatorBuilder> defaultBuilderPair() {
          return Pair.with(TYPE_PROPERTY_KEY, new SdkDefaultTlsProtocolNegotiatorBuilder());
      }
      
      /**
       * Retrieves the type of ProtocolNegotiatorBuilder configured for the SDK.
       *
       * @return the type of ProtocolNegotiatorBuilder
       */
      @Override
      public String type() {
          return super.actualType;
      }
  }
  