Use Case 37 - Get System Metadata for Object

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Goal

Retrieve the system metadata for an object identified by some identifier.

Summary

A client has an identifier for some object within the DataONE system and is attempting to retrieve system metadata describing the object. If the object exists on the node and the user has READ permission on the object, then the bytes of the system metadata object are returned, otherwise an error condition occurs.

Note that Member Nodes do not store authoritative copies of system metadata, but they still need to implement this operation.

Actors

• Client requesting object
• Coordinating Node
• Member Node

Preconditions

• Client has authenticated to the desired level (e.g. client may not have authenticated, so access might be anonymous).

Triggers

• System metadata is requested from the DataONE system.

Post Conditions

• The client has a copy of the system metadata document (or an error message in the case of failure)

Figure 1. Use case 37 diagram showing actors and components involved in this action.

Figure 2. Sequence diagram for Use Case 37 illustrating the sequence for retrieving the system metadata for an object identified by PID from a Coordinating Node.