Dataflow Streaming example with Scio

This is the example used in the Scio/Scala workshop in the Beam Summit 2021

• https://2021.beamsummit.org/sessions/scala-streaming-pipeline-using-scio/
• Slides in PDF

Branches in this repo:

• master, wih incomplete code with some exercises
• solution, with the solution to the exercises

Description of the pipeline

This pipeline takes some JSON data from a public PubSub topic, parses the JSON strings into a custom case class, aggregates some of the produced objects, and writes some output to BigQuery.

You need to have a project in Google Cloud Platform in order to run this pipeline.

How to launch the pipeline

Run sbt stage to generate a package for the pipeline, and the use the launch script with your project name

$ ./launch.sh $MY_PROJECT_NAME

You should have installed gcloud authenticated with the necessary credentials, or those credentials should be available in the environment variable GOOGLE_APPLICATION_CREDENTIALS. For more details see https://cloud.google.com/docs/authentication/getting-started

In the Dataflow UI, you should a graph of the pipeline like this one:

The script assumes that you want to launch the pipeline in us-east1 and that you have the following resources in your project already created

• A BigQuery dataset called taxi_rides
• A Cloud Storage bucket called gs://${MY_PROJECT_NAME}

You should create both resources, in the same region as where you are launching the pipeline.

The launch script will delete tables in your BigQuery dataset, so use a new sandbox dataset to try this pipeline out.

Input data

The pipeline reads data from this public PubSub topic:

projects/pubsub-public-data/topics/taxirides-realtime

Output data

The pipeline will create three tables in BigQuery:

• rides, with the same schema and contents as the incoming messages
• agg, with Taxi rides aggregated together
• errors, with details about any message that could not be parsed from the input data source.

Testing

The pipeline comes with a set of unit tests. To run them, please do

sbt test

In the master branch, one test will fail because one of the exercises is incomplete.

License

Copyright 2011 Israel Herraiz

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an " AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.