Discovery
Metadata can be used to tag different CDAP components so that they are easily identifiable and managed. This helps in discovering CDAP components.
For example, you can tag a dataset as experimental or an application as production. These entities can then be discovered by using search queries with the annotated metadata.
Using search, you can discover entities:
that have a particular value for any key in their properties;
that have a particular key with a particular value in their properties; or
that have a particular tag.
You can find a dataset that has a "field with the given name" or a "field with the given name and the given type".
To search metadata, you can use the Metadata HTTP RESTful API.
Lineage
Lineage can be retrieved for dataset entities. A lineage shows, for a specified time range, all data access of the entity and details of where that access originated from.
For datasets, lineage can indicate if a dataset access was for reading, writing, or both, if the methods in the dataset have appropriate annotations. If annotations are absent, lineage can only indicate that a dataset access took place, and does not provide indication if that access was for reading or writing.