content: /*
   * 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.kafka.streams;
  
  import org.apache.kafka.streams.processor.TopicNameExtractor;
  import org.apache.kafka.streams.processor.api.ProcessorContext;
  import org.apache.kafka.streams.processor.api.ProcessorSupplier;
  import org.apache.kafka.streams.processor.api.Record;
  import org.apache.kafka.streams.processor.internals.StreamTask;
  
  import java.util.Set;
  import java.util.regex.Pattern;
  
  /**
   * A meta representation of a {@link Topology topology}.
   * <p>
   * The nodes of a topology are grouped into {@link Subtopology sub-topologies} if they are connected.
   * In contrast, two sub-topologies are not connected but can be linked to each other via topics, i.e., if one
   * sub-topology {@link Topology#addSink(String, String, String...) writes} into a topic and another sub-topology
   * {@link Topology#addSource(String, String...) reads} from the same topic.
   * Message {@link ProcessorContext#forward(Record, String) forwards} using custom Processors are not considered in the topology graph.
   * <p>
   * When {@link KafkaStreams#start()} is called, different sub-topologies will be constructed and executed as independent
   * {@link StreamTask tasks}.
   */
  public interface TopologyDescription {
      /**
       * A connected sub-graph of a {@link Topology}.
       * <p>
       * Nodes of a {@code Subtopology} are connected
       * {@link Topology#addProcessor(String, ProcessorSupplier, String...) directly} or indirectly via
       * {@link Topology#connectProcessorAndStateStores(String, String...) state stores}
       * (i.e., if multiple processors share the same state).
       */
      interface Subtopology {
          /**
           * Internally assigned unique ID.
           * @return the ID of the sub-topology
           */
          @SuppressWarnings("unused")
          int id();
  
          /**
           * All nodes of this sub-topology.
           * @return set of all nodes within the sub-topology
           */
          @SuppressWarnings("unused")
          Set<Node> nodes();
      }
  
      /**
       * Represents a {@link Topology#addGlobalStore(org.apache.kafka.streams.state.StoreBuilder, String,
       * org.apache.kafka.common.serialization.Deserializer, org.apache.kafka.common.serialization.Deserializer, String,
       * String, org.apache.kafka.streams.processor.api.ProcessorSupplier) global store}.
       * Adding a global store results in adding a source node and one stateful processor node.
       * Note, that all added global stores form a single unit (similar to a {@link Subtopology}) even if different
       * global stores are not connected to each other.
       * Furthermore, global stores are available to all processors without connecting them explicitly, and thus global
       * stores will never be part of any {@link Subtopology}.
       */
      interface GlobalStore {
          /**
           * The source node reading from a "global" topic.
           * @return the "global" source node
           */
          @SuppressWarnings("unused")
          Source source();
  
          /**
           * The processor node maintaining the global store.
           * @return the "global" processor node
           */
          @SuppressWarnings("unused")
          Processor processor();
  
          @SuppressWarnings("unused")
          int id();
      }
  
      /**
       * A node of a topology. Can be a source, sink, or processor node.
       */
      interface Node {
          /**
           * The name of the node. Will never be {@code null}.
           * @return the name of the node
           */
          @SuppressWarnings("unused")
          String name();
          /**
           * The predecessors of this node within a sub-topology.
           * Note, sources do not have any predecessors.
           * Will never be {@code null}.
           * @return set of all predecessors
           */
          @SuppressWarnings("unused")
          Set<Node> predecessors();
          /**
           * The successor of this node within a sub-topology.
           * Note, sinks do not have any successors.
           * Will never be {@code null}.
           * @return set of all successor
           */
          @SuppressWarnings("unused")
          Set<Node> successors();
      }
  
  
      /**
       * A source node of a topology.
       */
      interface Source extends Node {
  
          /**
           * The topic names this source node is reading from.
           * @return a set of topic names
           */
          @SuppressWarnings("unused")
          Set<String> topicSet();
  
          /**
           * The pattern used to match topic names that is reading from.
           * @return the pattern used to match topic names
           */
          @SuppressWarnings("unused")
          Pattern topicPattern();
      }
  
      /**
       * A processor node of a topology.
       */
      interface Processor extends Node {
          /**
           * The names of all connected stores.
           * @return set of store names
           */
          @SuppressWarnings("unused")
          Set<String> stores();
      }
  
      /**
       * A sink node of a topology.
       */
      interface Sink extends Node {
          /**
           * The topic name this sink node is writing to.
           * Could be {@code null} if the topic name can only be dynamically determined based on {@link TopicNameExtractor}
           * @return a topic name
           */
          @SuppressWarnings("unused")
          String topic();
  
          /**
           * The {@link TopicNameExtractor} class that this sink node uses to dynamically extract the topic name to write to.
           * Could be {@code null} if the topic name is not dynamically determined.
           * @return the {@link TopicNameExtractor} class used get the topic name
           */
          @SuppressWarnings("unused")
          TopicNameExtractor<?, ?> topicNameExtractor();
      }
  
      /**
       * All sub-topologies of the represented topology.
       * @return set of all sub-topologies
       */
      @SuppressWarnings("unused")
      Set<Subtopology> subtopologies();
  
      /**
       * All global stores of the represented topology.
       * @return set of all global stores
       */
      @SuppressWarnings("unused")
      Set<GlobalStore> globalStores();
  
  }
  