java - 了解 spring 集成服务激活器

Question

我接到一项任务，要对十年前开发的 spring-integration 项目进行一些修改，我知道它是如何工作的，所以我查看了一些spring-integration 教程，虽然我没有完全理解它，但我了解了一些基本知识。现在我尝试在进行更改之前了解以下 spring-integration 配置 spring.integration.version 2.2.4.RELEASE 的片段

<!-- Currency Pull from NetSuite -->
<int:gateway id="currencySyncGateway" service-interface="com.integration.service.INetSuiteCurrencyPullService" default-request-channel="currenciesFromNetSuite" />


<bean id="nsCurrencyPullService" class="com.integration.service.impl.NetSuiteCurrencyPullService" />
<int:channel id="currenciesFromNetSuite" />
<int:service-activator input-channel="currenciesFromNetSuite" ref="nsCurrencyPullService" method="getCurrencies" output-channel="pushCurrenciesToDB" />

<bean id="msSqlCurrencyPushService" class="com.integration.service.impl.MSSQLCurrencyPushService" />
<int:channel id="pushCurrenciesToDB" />
<int:service-activator input-channel="pushCurrenciesToDB" ref="msSqlCurrencyPushService" method="saveCurrenciesToDB" />

下面是上述bean对应的类

INetSuiteCurrencyPullService

public interface INetSuiteCurrencyPullService {

    List<Currency> getCurrencies(String in);

}

NetSuiteCurrencyPullService

public class NetSuiteCurrencyPullService implements INetSuiteCurrencyPullService {

    @Autowired
    INetSuiteClient restletClient;

    @Override
    public List<Currency> getCurrencies(String in) {
        LOGGER.info("Retrieving currencies from NetSuite...");
        PullCurrenciesRestletResponse response = restletClient.pullCurrencies();
        LOGGER.debug("Restlet response: {}", response);

        if ("SUCCESS".equals(response.getError().getCode())) {
            LOGGER.info("Received restlet response: executionTimeMillis=" + response.getExecutionTimeMillis() + ", count=" + response.getCurrencies().size());
            return response.getCurrencies();
        } else {
            String msg = "Error retrieving currencies from NetSuite: " + response.getError().getMessage();
            LOGGER.error(msg);
            throw new RuntimeException(msg);
        }
    }

}

MSSQLCurrencyPushService

public class MSSQLCurrencyPushService implements IMSSQLCurrencyPushService {

    @Autowired
    CurrencyConversionRepository currencyConversionRepository;

    @Override
    public List<Currency> saveCurrenciesToDB(List<Currency> in) {
        // logic to save Currency in DB     
        return in;
    }
}

下面是我对应用程序启动后的上述 spring-integration 配置的理解(如果错误，请更正)
1. Spring首先为INetSuiteCurrencyPullService初始化一个代理对象
2.然后实例化nsCurrencyPullService bean
3.然后调用nsCurrencyPullService的getCurrency方法
4. 并将输出传递给 msSqlCurrencyPushService 的 saveCurrencyToDB 方法

请帮我解决以下问题
那么上述步骤只在spring应用启动时执行？
或者是在应用程序启动后定期进行？
如果定期执行，我可以在哪里检查 nsCurrencyPullService 调用的轮询频率？

Answer 1

So the above steps are performed only during the spring application startup?

基础设施(bean)创建在应用程序上下文初始化期间执行一次。这些组件使用 MessageChannel 连接在一起。当网关被调用时，有效负载被包装在消息中并发送到 channel 。默认情况下， channel 是 DirectChannel，这意味着直接在调用者的线程上调用服务。

第一个服务的输出通过 channel 发送到第二个服务；再次在调用者的线程上。该服务的结果作为方法调用的结果返回给调用者。

polling frequency

这种情况下没有轮询；消息由网关的调用者发送到集成流中。

实现同样功能的现代方法是使用 DSL。

@Bean
public IntegrationFlow() {
    return IntegrationFlows.from(INetSuiteCurrencyPullService.class)
         .handle("bean1", "method1")
         .handle("bean2", "method2")
         .get();
}