Question

我已经在我的节点上创建了CordaService。我希望这项服务能够根据各种条件启动流程。但是，提供给服务的ServiceHub不提供启动流的功能。

服务启动流程是否有任何流程？我该怎么办？

Answer 1

是。只需在其构造函数中传递CordaService AppServiceHub而不是ServiceHub。

AppServiceHub接口扩展了ServiceHub接口，使节点能够启动流：

interface AppServiceHub : ServiceHub {

    fun <T> startFlow(flow: FlowLogic<T>): FlowHandle<T>

    fun <T> startTrackedFlow(flow: FlowLogic<T>): FlowProgressHandle<T>
}

Answer 2

是的，将AppServiceHub传递给构造函数

在科特林：

class MyCordaService(private val serviceHub: AppServiceHub) : SingletonSerializeAsToken() {

    init {
        // code ran at service creation / node startup
    }

    // public api of service
}

或Java：

public class MyCordaService extends SingletonSerializeAsToken {

    private AppServiceHub serviceHub;

    public MyCordaService(AppServiceHub serviceHub) {
        this.serviceHub = serviceHub;
        // code ran at service creation / node startup
    }

    // public api of service
}

重要：为避免运行的节点之间可能出现任何死锁，请从其自己的线程

开始内部流程

例如：

public class MyCordaService extends SingletonSerializeAsToken {

    private AppServiceHub serviceHub;

    public MyCordaService(AppServiceHub serviceHub) {
        this.serviceHub = serviceHub;
        // code ran at service creation / node startup
    }

    // public api of service
   public void doSomething(){   
    // do something and start a new flow
    Thread flowThread = new Thread(new StartFlow());
    flowThread.start();
   }

   private class StartFlow implements Runnable {
     @Override
        public void run() {
         // start new flow
         CordaFuture<SignedTransaction> cordaFuture=  appServiceHub.startFlow(new 
         Flow(params).getReturnValue();

         SignedTransaction signedTransaction = cordaFuture.get();
        }
   }
}

在Corda中，如何从服务启动流程？

2 个答案: