Sample command-line program for interacting with the Google Cloud Tasks API using pull queues.

Pull queues let you add tasks to a queue, then programatically remove and interact with them. Tasks can be added or processed in any environment, such as on Google App Engine or Google Compute Engine.

Quickstart.java is a simple command-line program to demonstrate listing queues, creating tasks, and pulling and acknowledging tasks.

• Set up a Google Cloud Project and enable billing.
• Enable the Cloud Tasks API.
• Download and install the Cloud SDK.
• Download and install Maven.

To create a queue using the Cloud SDK, use the following gcloud command:

gcloud beta tasks queues create-pull-queue my-pull-queue

In this example, the queue will be named my-pull-queue.

From the project folder, build your project with:

mvn clean install

Optionally, you can set up your settings as environment variables:

export GOOGLE_CLOUD_PROJECT=<YOUR_PROJECT_ID>
export LOCATION_ID=<YOUR_ZONE>
export QUEUE_ID=my-pull-queue

Next, create a task for a queue:

mvn exec:java -Dexec.mainClass="com.example.Quickstart" \
    -Dexec.args="create-task \
    --project $GOOGLE_CLOUD_PROJECT --queue $QUEUE_ID --location $LOCATION_ID"

Finally, pull and acknowledge a task:

mvn exec:java -Dexec.mainClass="com.example.task.Quickstart" \
    -Dexec.args="lease-and-ack-task \
    --project $GOOGLE_CLOUD_PROJECT --queue $QUEUE_ID --location $LOCATION_ID"

Note that usually, there would be a processing step in between pulling a task and acknowledging it.