养蜂人 (Beekeeper)

养蜂人研究蜜蜂繁殖规律，计算每只蜜蜂 (雄蜂/雌蜂) 的祖先数量。因为蜜蜂繁殖规律和黄金分割数列相关，所以养蜂人同时消费技工提供的计算服务。

研究(http://www.dave-cushman.net/bee/fibonacci.html)表明，雄蜂(Drone)由未受精卵孵化而生，只有母亲；而雌蜂(Queen)由受精卵孵化而生，既有母又有父。

Credit: Dave Cushman’s website

参考上图，蜜蜂的某一代祖先数量符合黄金分割数列的模型，由此我们可以很快实现服务功能。

蜜蜂繁殖规律研究服务

首先我们定义黄金数列运算接口：

public interface FibonacciCalculator {
  long term(int n);
}

接下来定义并实现蜜蜂繁殖规律研究服务:

interface BeekeeperService {
  long ancestorsOfDroneAt(int generation);

  long ancestorsOfQueenAt(int generation);
}

class BeekeeperServiceImpl implements BeekeeperService {

  private final FibonacciCalculator fibonacciCalculator;

  BeekeeperServiceImpl(FibonacciCalculator fibonacciCalculator) {
    this.fibonacciCalculator = fibonacciCalculator;
  }

  @Override
  public long ancestorsOfDroneAt(int generation) {
    if (generation <= 0) {
      return 0;
    }
    return fibonacciCalculator.term(generation + 1);
  }

  @Override
  public long ancestorsOfQueenAt(int generation) {
    if (generation <= 0) {
      return 0;
    }
    return fibonacciCalculator.term(generation + 2);
  }
}

这里我们用到之前定义的 FibonacciCalculator 接口，并希望通过这个接口远程调用技工服务端点。@RpcReference 注释能帮助我们自动从Service Center中获取 microserviceName = “worker”, schemaId = “fibonacciRpcEndpoint” ，即服务名为 worker 已经schema ID为 fibonacciRpcEndpoint的端点：


@Configuration
class BeekeeperConfig {

  @RpcReference(microserviceName = "worker", schemaId = "fibonacciRpcEndpoint")
  private FibonacciCalculator fibonacciCalculator;

  @Bean
  BeekeeperService beekeeperService() {
    return new BeekeeperServiceImpl(fibonacciCalculator);
  }
}

我们在技工一节已定义好对应的服务名和schema ID端点，通过上面的配置，ServiceComb 会自动将远程技工服务实例和 FibonacciCalculator 绑定在一起。

养蜂人服务端点

与上一节技工服务相似，我们在这里也需要提供养蜂人服务端点，让用户可以进行调用：


@RestSchema(schemaId = "beekeeperRestEndpoint")
@RequestMapping("/rest")
@Controller
public class BeekeeperController {

  private static final Logger logger = LoggerFactory.getLogger(BeekeeperController.class);

  private final BeekeeperService beekeeperService;

  @Autowired
  BeekeeperController(BeekeeperService beekeeperService) {
    this.beekeeperService = beekeeperService;
  }

  @RequestMapping(value = "/drone/ancestors/{generation}", method = GET, produces = APPLICATION_JSON_UTF8_VALUE)
  @ResponseBody
  public Ancestor ancestorsOfDrone(@PathVariable int generation) {
    logger.info(
        "Received request to find the number of ancestors of drone at generation {}",
        generation);

    return new Ancestor(beekeeperService.ancestorsOfDroneAt(generation));
  }

  @RequestMapping(value = "/queen/ancestors/{generation}", method = GET, produces = APPLICATION_JSON_UTF8_VALUE)
  @ResponseBody
  public Ancestor ancestorsOfQueen(@PathVariable int generation) {
    logger.info(
        "Received request to find the number of ancestors of queen at generation {}",
        generation);

    return new Ancestor(beekeeperService.ancestorsOfQueenAt(generation));
  }
}

class Ancestor {
  private long ancestors;

  Ancestor() {
  }

  Ancestor(long ancestors) {
    this.ancestors = ancestors;
  }

  public long getAncestors() {
    return ancestors;
  }
}

因为养蜂人需要消费技工提供的服务，所以其 microservice.yaml 配置稍有不同：

# all interconnected microservices must belong to an application wth the same ID
APPLICATION_ID: company
service_description:
# name of the declaring microservice
  name: beekeeper
  version: 0.0.1
cse:
  service:
    registry:
      address: http://sc.servicecomb.io:30100
  rest:
    address: 0.0.0.0:8090
  handler:
    chain:
      Consumer:
        default: bizkeeper-consumer,loadbalance
  references:
#  this one below must refer to the microservice name it communicates with
    worker:
      version-rule: 0.0.1

这里我们需要定义 cse.references.worker.version-rule ，让配置名称中指向技工服务名 worker ，并匹配其版本号。

最后定义养蜂人服务应用入口：

@SpringBootApplication
@EnableServiceComb
public class BeekeeperApplication {

  public static void main(String[] args) {
    SpringApplication.run(BeekeeperApplication.class, args);
  }
}

本文转载自微服务蜂巢公众号。

原文链接：https://mp.weixin.qq.com/s?__biz=MzUxNTEwNTg5Mg==&mid=2247488670&idx=1&sn=7556990599cea8e0fd80ed54b9f39026&chksm=f9bae195cecd688332940d0b296909e8130d828104c36c20f49d76d43561f626eae24bd0c1ef&scene=0&xtrack=1&key=17fbc717c1803f309d535a4bdbc0f9c0d8d2089a5c7e455df8c0a5e6d824a6534b8476d2ad151cd45ed10eb7a15577914596444e867d96f615c277fc05fe951cef48de8b7d0732dcb4bc74f5c0e2f95a&ascene=14&uin=MTI5MjAyNjcyMQ%3D%3D&devicetype=Windows+10&version=62070158&lang=zh_CN&exportkey=AfH3CzqE%2F1ENttvg815y9Uo%3D&pass_ticket=oGcazNeaRfkuszcDU0L7jpfeTFZ3%2FULBAbPnhurUkiyW7DLvBVsoC%2Fh5OWX1zIsH

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