相关疑难解决方法(0)

我正在编写一个从Kafka 0.8读取的自定义DataFlow无界数据源.我想使用DirectPipelineRunner在本地运行它.但是,我得到以下stackstrace:

Exception in thread "main" java.lang.IllegalStateException: no evaluator registered for Read(KafkaDataflowSource)
        at com.google.cloud.dataflow.sdk.runners.DirectPipelineRunner$Evaluator.visitTransform(DirectPipelineRunner.java:700)
        at com.google.cloud.dataflow.sdk.runners.TransformTreeNode.visit(TransformTreeNode.java:219)
        at com.google.cloud.dataflow.sdk.runners.TransformTreeNode.visit(TransformTreeNode.java:215)
        at com.google.cloud.dataflow.sdk.runners.TransformHierarchy.visit(TransformHierarchy.java:102)
        at com.google.cloud.dataflow.sdk.Pipeline.traverseTopologically(Pipeline.java:252)
        at com.google.cloud.dataflow.sdk.runners.DirectPipelineRunner$Evaluator.run(DirectPipelineRunner.java:662)
        at com.google.cloud.dataflow.sdk.runners.DirectPipelineRunner.run(DirectPipelineRunner.java:374)
        at com.google.cloud.dataflow.sdk.runners.DirectPipelineRunner.run(DirectPipelineRunner.java:87)
        at com.google.cloud.dataflow.sdk.Pipeline.run(Pipeline.java:174)

这是有道理的,因为我没有在任何时候为我的自定义源注册评估者.

阅读https://github.com/GoogleCloudPlatform/DataflowJavaSDK,似乎只有有限来源的评估者才能注册.为自定义无界源定义和注册求值程序的推荐方法是什么？