This lab will simulate live highway sensor data which will be published to a Cloud Pub/Sub topic. Then, a Cloud Dataflow streaming pipeline will subscribe to it. The pipeline will take the streaming sensor data, transform it, and insert it into a BigQuery table. We will then view the streaming inserts in BigQuery while they are in progress, and attempt to gain some useful insights from the streaming data.
Successfully complete this lab by achieving the following learning objectives:
- Prepare Your Environment
Enable Pub/Sub and Dataflow APIs:
gcloud services enable dataflow.googleapis.com gcloud services enable pubsub.googleapis.com
Create a Cloud Storage bucket for Dataflow staging:
gsutil mb gs://$DEVSHELL_PROJECT_ID
Download the GitHub repository used for lab resources:
cd ~ git clone https://github.com/ACloudGuru-Resources/googledataengineer
- Create a Pub/Sub Topic
gcloud pubsub topics create sandiego
- Create a BigQuery Dataset to Stream Data Into
Create a BigQuery dataset to stream data into:
bq mk --dataset $DEVSHELL_PROJECT_ID:demos
The table will be named
average_speeds. We do not create the table, but Dataflow will create it within the dataset for us.
- View the Dataflow Template
We will not be interacting with the template directly. We will be using a script that will install the Java environment and execute the template as a Dataflow job:
- Create the Dataflow Streaming Job
Go to the Dataflow job script directory:
Execute the script that creates the Dataflow streaming job, and subscribe to the Pub/Sub topic.
This script passes along the Project ID, staging bucket (also the Project ID), and the name of the Java template to use:
./run_oncloud.sh $DEVSHELL_PROJECT_ID $DEVSHELL_PROJECT_ID AverageSpeeds
When complete, the streaming job will be subscribed to our Pub/Sub topic, and waiting for streaming input from our simulated sensor data.
- Publish Simulated Traffic Sensor Data to Pub/Sub via a Python Script and Pre-Created Dataset
Browse to the Python script directory:
Install any requirements for the Python script:
pip install -U google-cloud-pubsub
Download the simulated sensor data:
gsutil cp gs://la-gcloud-course-resources/sandiego/sensor_obs2008.csv.gz .
Execute the Python script to publish simulated streaming data to Pub/Sub:
./send_sensor_data.py --speedFactor=60 --project=$DEVSHELL_PROJECT_ID
- View the Streamed Data in BigQuery
In BigQuery, execute the following query to view the current streamed data, both in the table and in the streaming buffer:
SELECT * FROM `demos.average_speeds` LIMIT 1000
Notice the total count of records at the bottom. Wait about a minute and run the same query again (be sure to uncheck use cached results in query options) and notice that the number has increased.
- Use Aggregated Queries to Gain Insights
Let’s get some use out of this data. If we wanted to forecast some necessary road maintenance, we would need to know which lanes have the most traffic, to know which ones will require resurfacing first.
Enter the following query to view which lanes have the most sensor counts:
SELECT lane, count(lane) as total FROM `demos.average_speeds` GROUP BY lane ORDER BY total DESC
We can also view which lanes have the highest average speeds:
SELECT lane, avg(speed) as average_speed FROM `demos.average_speeds` GROUP BY lane ORDER BY average_speed DESC