Labels can be used as an alternative reference to an application in the Stream or Batch DSL.
The syntax is to add the label before the application name.
Labels must be unique within the entire definition and suffixed with a colon
For example, when a a stream is made up of multiple apps with the same name, they must be qualified with labels so they can be uniquely identified:
stream create --definition "http | firstLabel: transform --expression=payload.toUpperCase() | secondLabel: transform --expression=payload+'!' | log" --name myStreamWithLabels --deploy
This can be visualized in a graphical representation as follows:
Alternatively, they can be used to help make the visualization of the Stream and Batch job more descriptive. The example in Python Application shows an example of this style of usage.