Context Organization and Data Definitions
The Context Manager maintains the common clinical context data for a context session. The context manager organizes context data as a set of data items and groups the data items according to context subject. There are three classes of context subjects defined in the standard:
- Identity subjects - Identify real-world entities or concepts. For example, a specific patient or a specific clinical encounter.
- Annotation subjects - Contain data that describes or is otherwise pertinent to the entity or concept identified in an identity subject.
- Action subjects - Represent a task performed on behalf of the user. This includes the inputs needed to perform the task and the outputs that represent the result of the task.
Name/value pairs represent a context subject's data items. If the subject is an Identity subject, one value needs to represent the identifier for the real world entity or concept. If the subject is an Annotation subject, each item in the pair represents a data item within the overall annotation. If the subject is an Action subject, each item represents the action request or the result of performing the action. To ensure applications have a clear unambiguous understanding of the context subject and the associated data definitions at development, HL7 has defined standard subjects. These subjects have predefined allowable names and standard data items. In addition to the standard subjects, organizations can define custom subjects.
The Identity and Annotation subjects persist in the context for the duration of the context session. The data represented by these subjects is updated over time and serve as the basis for context sharing. The Action subject's data is transient and does not persist within the context. It exists in the context only from the time of the action request until the completion of the action.