In Part 1 and 2, my colleagues Megan and Alex introduced you to the Pub/Sub service and its official client libraries. In this last section, I will cover some remaining topics including push subscriptions, the emulator, IAM policies, and health metrics.

What is a push subscription and when do I use it?

Push subscriptions allow Pub/Sub to come to you: Pub/Sub delivers messages to a predefined HTTPS address (also called a push endpoint) as a HTTP POST request.

Unlike a pull subscription, where you actively ask Pub/Sub for messages, a push subscription lets you configure a push endpoint, and Pub/Sub delivers messages to this push endpoint.

You should consider a push subscription if any of the following applies:

  • You are not able to include any client library code in your subscriber application.
  • Your subscriber is not allowed…


You’re not alone. When writing the first Apache Beam pipeline in Java, many of us were stopped in our way by this error message:

Exception in thread “main” java.lang.IllegalArgumentException: Unable to infer a coder and no Coder was specified. Please set a coder by invoking Create.withCoder() explicitly or a schema by invoking Create.withSchema().

This article demonstrates a few ways to make the error go away by serializing your Plain Old Java Objects (POJOs) using:

  • Serializable
  • Apache Avro
  • Protocol Buffers

Full examples are available on GitHub.

Let’s look at a simple Beam pipeline. It creates a collection of Player objects and…


Featured in many Google Cloud quickstarts and tutorials, this public Pub/Sub topic projects/pubsub-public-data/topics/taxirides-realtime allows anyone to attach a subscription to it and listen to fake taxi rides data in real time. Does such a public topic exist for Pub/Sub Lite too? In this blog post, I will explain why having a public Pub/Sub Lite topic is infeasible, how you can still share a Pub/Sub Lite topic resource with others, and finally, what you can do to route the fake taxi rides data from the Pub/Sub public topic to your Pub/Sub Lite topic.

Before I delve into Pub/Sub Lite, let me…


Unless you work in certain very specific fields like self-driving car engineering, you may have not heard of Kalman Filters or have largely forgotten what you once learned about them in school. I myself had relegated them to the deep recesses of my mind. Admittedly, I have only really studied Kalman Filters in a nanodegree program with Udacity in self-driving car engineering, and that was three years ago. But recently, work organized a learning day event that let me pursue something of my own interest in the name of learning, and Pub/Sub has released its official C++ client library and…

Tianzi Cai

Developer Relations Engineer, Google Cloud Pub/Sub

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