Packages

•  package root

  Definition Classes

  root

•  package org

  Definition Classes

  root

•  package apache

  Definition Classes

  org

•  package pekko

  Definition Classes

  apache

•  package stream

  Definition Classes

  pekko

•  package scaladsl

  Scala API: The flow DSL allows the formulation of stream transformations based on some input.

  Scala API: The flow DSL allows the formulation of stream transformations based on some input. The starting point is called Source and can be a collection, an iterator, a block of code which is evaluated repeatedly or a org.reactivestreams.Publisher. A flow with an attached input and open output is also a Source.

  A flow may also be defined without an attached input or output and that is then a Flow. The Flow can be connected to the Source later by using Source#via with the flow as argument, and it remains a Source.

  Transformations can be appended to Source and Flow with the operations defined in FlowOps. Each DSL element produces a new flow that can be further transformed, building up a description of the complete transformation pipeline.

  The termination point of a flow is called Sink and can for example be a Future or org.reactivestreams.Subscriber. A flow with an attached output and open input is also a Sink.

  If a flow has both an attached input and an attached output it becomes a RunnableGraph. In order to execute this pipeline the flow must be materialized by calling RunnableGraph#run on it.

  You can create your Source, Flow and Sink in any order and then wire them together before they are materialized by connecting them using Flow#via and Flow#to, or connecting them into a GraphDSL with fan-in and fan-out elements.

  See Reactive Streams for details on org.reactivestreams.Publisher and org.reactivestreams.Subscriber.

  It should be noted that the streams modeled by this library are “hot”, meaning that they asynchronously flow through a series of processors without detailed control by the user. In particular it is not predictable how many elements a given transformation step might buffer before handing elements downstream, which means that transformation functions may be invoked more often than for corresponding transformations on strict collections like scala.collection.immutable.List. *An important consequence* is that elements that were produced into a stream may be discarded by later processors, e.g. when using the #take operator.

  By default every operation is executed within its own org.apache.pekko.actor.Actor to enable full pipelining of the chained set of computations. This behavior is determined by the org.apache.pekko.stream.Materializer which is required by those methods that materialize the Flow into a series of org.reactivestreams.Processor instances. The returned reactive stream is fully started and active.

  Definition Classes

  stream

•  object MergeHub

  A MergeHub is a special streaming hub that is able to collect streamed elements from a dynamic set of producers.

  A MergeHub is a special streaming hub that is able to collect streamed elements from a dynamic set of producers. It consists of two parts, a Source and a Sink. The Source streams the element to a consumer from its merged inputs. Once the consumer has been materialized, the Source returns a materialized value which is the corresponding Sink. This Sink can then be materialized arbitrary many times, where each of the new materializations will feed its consumed elements to the original Source.

  Definition Classes

  scaladsl

• DrainingControl
• ProducerFailed

org.apache.pekko.stream.scaladsl.MergeHub

ProducerFailed