The left-shift operator (<<) normally shifts an integer’s binary representation left. Airflow overloads it so tasks can express execution dependencies instead of performing bit shifting. section 2.2
Order a launch-data workflow
A download task must finish before image processing, which must finish before notification. Express that sequence as: download_launches << get_pictures << notify. In Airflow’s dependency notation, the equivalent right-shift form shown in the workflow is download_launches >> get_pictures >> notify: each downstream task waits for its upstream task to complete successfully. section 2.2
Listing 2.5 Defining the order of task execution
download_launches >> get_pictures >> notify #1
Inspect the compact task-ordering listing and compare the readable dependency chain with the workflow’s task relationships. section 2.2
