Oozie is used in Hadoop for scheduling a workflow of jobs. Users will create workflows in Directed Acyclic Graphs which says which job should be done after one job. Oozie helps us to start, stop or rerun the jobs. We can even skip a particular node if there is any downtime or failure.
Oozie consists of two parts as the Workflow engine and Coordinator engine. Workflow engine run workflows composed of jobs like MapReduce, Pig, Hive. The coordinator engine runs workflow jobs based on data availability and as per schedules defined at the start. Oozie has a provision to specify the frequency of execution of a job, to send email notifications after completing jobs.
You can know more about the Hadoop ecosystem from this video by intellipaat: