Sink node

As explained in Software Design for Python Programmers

A subscriber is a software component that receives notifications from a publisher and may request and process the publisher's new content.

A subscriber is a component that receives notifications from a publisher and may request, ignore, or process newly available content independently. The publisher tracks subscribers and remains unaware of their implementations. section 12.1 section 12.1.1

A flexible subscriber arrangement lets components:

• Subscribe or unsubscribe without changing publisher code. section 12.1.1
• Choose whether and how to process each notification. section 12.1
• Maintain different responsibilities, such as logging events, accumulating a table, or displaying a graph. section 12.1 section 12.1.2

Figure 12.1 An example of the publisher–subscriber model. The publisher component produces hit events that are consumed as they occur by the subscriber components to generate the various reports.

Shows a publisher producing events consumed by multiple subscriber components. section 12.1

How Software Design for Python Programmers covers it

How deep it goes

Defines notification, optional retrieval, processing, and subscription behavior, stopping short of a full decoupled implementation.

Examples

Uses news readers and baseball log, table, and graph report generators as subscriber examples.

What it assumes

Assumes only that a publisher produces content and that consuming components can receive and process it.

What you can do after

Apply the subscriber role when designing components that independently consume publisher events.

How it connects

Connects subscribers to the Observer Design Pattern, publisher–subscriber model, producer–consumer model, publishers, subjects, and observers.

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Also explained in

• 

  liveBookmanning.com
  Learn Docker in a Month of Lunches, Second EditionA subscriber is a messaging component that listens for and receives messages published to a subject.
• 

  liveBookmanning.com
  Advanced Algorithms and Data StructuresA sink is the distinguished network vertex into which flow is delivered and which has no outbound flow.

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Related concepts

• data streamkind of · A data stream is an ordered sequence of data items or events made available incrementally for consumption or processing.
• MockConsumerimplemented by · MockConsumer is a Kafka client test class that simulates a consumer without reading records from a live Kafka broker.
• messageuses · A message is a discrete unit of information or data represented, processed, or exchanged in a communication context.
• topicuses · A topic is a named messaging destination or stream to which producers publish messages or records and from which consumers receive or read them.
• reactive streampart of · Reactive Streams is a standard defining interfaces and signaling rules for asynchronous stream processing with nonblocking backpressure between producers and consumers.

This explainer was generated by Manning's knowledge graph from the text of Software Design for Python Programmers. The section links point to the parts of the book it draws on.