Specifies the processing model used by a
[google.dataflow.v1beta3.Job], which determines the way the Job is
managed by the Cloud Dataflow service (how workers are scheduled, how
inputs are sharded, etc).
value: 0 The type of the job is unspecified, or unknown.
value: 1 A batch job with a well-defined end point: data is read, data is
processed, data is written, and the job is done.
value: 2 A continuously streaming job with no end: data is read,
processed, and written continuously.