juplo.de Git - demos/microservices/blob - details/src/main/java/de/trion/microservices/details/DetailsService.java

   1 package de.trion.microservices.details;
   2
   3
   4 import de.trion.microservices.avro.Order;
   5 import static org.springframework.http.MediaType.APPLICATION_JSON;
   6 import io.confluent.kafka.streams.serdes.avro.SpecificAvroSerde;
   7 import java.net.URI;
   8 import java.util.Properties;
   9 import javax.annotation.PostConstruct;
  10 import javax.annotation.PreDestroy;
  11 import org.apache.kafka.common.serialization.Serdes;
  12 import org.apache.kafka.streams.KafkaStreams;
  13 import org.apache.kafka.streams.StreamsBuilder;
  14 import org.apache.kafka.streams.Topology;
  15 import org.apache.kafka.streams.kstream.Materialized;
  16 import org.apache.kafka.streams.state.QueryableStoreTypes;
  17 import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
  18 import org.apache.kafka.streams.state.StreamsMetadata;
  19 import org.slf4j.Logger;
  20 import org.slf4j.LoggerFactory;
  21 import org.springframework.http.HttpStatus;
  22 import org.springframework.http.MediaType;
  23 import org.springframework.http.ResponseEntity;
  24 import org.springframework.web.bind.annotation.GetMapping;
  25 import org.springframework.web.bind.annotation.PathVariable;
  26 import org.springframework.web.bind.annotation.RestController;
  27
  28
  29 @RestController
  30 public class DetailsService
  31 {
  32   final static Logger LOG = LoggerFactory.getLogger(DetailsService.class);
  33
  34   private final String topic;
  35   private final String host;
  36   private final int port;
  37   private final KafkaStreams streams;
  38
  39
  40   public DetailsService(ApplicationProperties config)
  41   {
  42     topic = config.topic;
  43
  44     String[] splitted = config.applicationServer.split(":");
  45     host = splitted[0];
  46     port = Integer.parseInt(splitted[1]);
  47
  48     Properties properties = new Properties();
  49     properties.put("bootstrap.servers", config.bootstrapServers);
  50     properties.put("application.id", "details");
  51     properties.put("application.server", config.applicationServer);
  52     properties.put("schema.registry.url", config.schemaRegistryUrl);
  53     properties.put("default.key.serde", Serdes.String().getClass());
  54     properties.put("default.value.serde", SpecificAvroSerde.class);
  55
  56     StreamsBuilder builder = new StreamsBuilder();
  57     builder.table(topic, Materialized.as(topic));
  58
  59     Topology topology = builder.build();
  60     streams = new KafkaStreams(topology, properties);
  61     streams.setUncaughtExceptionHandler((Thread t, Throwable e) ->
  62     {
  63       LOG.error("Unexpected error in thread {}: {}", t, e.toString());
  64       try
  65       {
  66         streams.close();
  67       }
  68       catch (Exception ex)
  69       {
  70         LOG.error("Could not close KafkaStreams!", ex);
  71       }
  72     });
  73   }
  74
  75
  76   @GetMapping(
  77       path = "/orders/{id}",
  78       produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
  79   public ResponseEntity<?> getOrder(@PathVariable String id)
  80   {
  81     StreamsMetadata metadata = streams.metadataForKey(topic, id, Serdes.String().serializer());
  82     LOG.debug("Local store for {}: {}:{}", id, metadata.host(), metadata.port());
  83
  84     if (port != metadata.port() || !host.equals(metadata.host()))
  85     {
  86       URI location = URI.create("http://" + metadata.host() + ":" + metadata.port() + "/" + id);
  87       LOG.debug("Redirecting to {}", location);
  88       return
  89           ResponseEntity
  90               .status(HttpStatus.TEMPORARY_REDIRECT)
  91               .location(location)
  92               .build();
  93     }
  94
  95     ReadOnlyKeyValueStore<String, Order> orders;
  96     orders = streams.store(topic, QueryableStoreTypes.keyValueStore());
  97     Order order = orders.get(id);
  98     return order == null
  99         ? ResponseEntity.notFound().build()
 100         : ResponseEntity.ok().contentType(APPLICATION_JSON).body(order.toString());
 101   }
 102
 103
 104   @PostConstruct
 105   public void start()
 106   {
 107     streams.start();
 108   }
 109
 110   @PreDestroy
 111   public void stop()
 112   {
 113     streams.close();
 114   }
 115 }