Use Case 42 - Update System Metadata Properties¶

Goal¶

Alter mutable properties of System Metadata.

Summary¶

System Metadata provides low level information about each object in DataONE and inlcudes properties that are immutable and others that may be mutated by different agents.

This use case desribes the general pattern of updating System Metadata properties by agents with authority to do so.

In version 1.x of the DataONE infrastructure, System Metadata may only be altered through Coordinating Nodes (after creation and synchronization).

In version 2.x of the DataONE infrastructure, properties of System Metadata are managed by the Authoritative Member Node with the exception of Replica information, which is managed by the Coordinating Nodes. In version 2.x, the System Metadata serialVersion property is only updated by Coordinating Nodes during replication processing. Only the Authoritative Member Node can update dataSysMetadataModified.

Actors¶

A content owner
Coordinating Node
Member Node
Replication target Member Node

Preconditions¶

Object exists within the DataONE system

Triggers¶

A user or agent wishes to alter mutable properties of System Metadata for an object.

Post Conditions¶

The properties of System Metadata are altered
All replicas of System Metadata are in sync
Search indices are updated to reflect the change

Process¶

$@startuml images/42_seq_a.png autonumber actor Bob participant "Authoritative" as MN <<Member Node>> participant "Coordinating Node" as CN <<Coordinating Node>> participant "Replica" as MN_repl <<Member Node>> note right of CN System Metadata Serial Version = 1 dateSysMetadataModified = t1 end note note right of MN System Metadata Serial Version = 1 dateSysMetadataModified = t1 end note note right of MN_repl System Metadata Serial Version = 1 dateSysMetadataModified = t1 end note Bob -> CN : Alter Property activate CN CN -> CN : update property\nserialVersion++\ndateSysMetadataModified = now() note right of CN System Metadata Serial Version = 2 dateSysMetadataModified = t2 end note CN ->] : <<internal>> Notify System Metadata Changed note right of CN Indexing and other CN services are notified of the change end note CN -> Bob: ack deactivate CN group Update All Member Nodes CN -> MN: systemMetadataChanged activate MN CN->MN_repl: systemMetadataChanged activate MN_repl MN -> CN: getSystemMetadata activate CN CN -> MN: SystemMetadata deactivate CN MN -> MN : update property note right of MN System Metadata Serial Version = 2 dateSysMetadataModified = t2 end note deactivate MN MN_repl -> CN: getSystemMetadata activate CN CN -> MN_repl: SystemMetadata deactivate CN MN_repl -> MN_repl : update property note right of MN_repl System Metadata Serial Version = 2 dateSysMetadataModified = t2 end note deactivate MN_repl end @enduml$

Figure 2a. Sequence diagram for Use Case 42 illustrating the high level sequence of operations associated with altering system metadata of an object for version 1.x infrastructure where Coordinating Nodes are the authoritative source for System Metadata. In this scenario, user Bob updates properties of System Metadata (e.g. Access Policy) for an object, and that change is propogated to copies throughout the federation.

$@startuml images/42_seq_b.png autonumber actor Bob participant "Authoritative" as MN <<Member Node>> participant "Coordinating Node" as CN <<Coordinating Node>> participant "Replica" as MN_repl <<Member Node>> Bob -> MN: getSystemMetadata note right of MN System Metadata serialVersion = 10 dateSysMetadataModified = t1 end note note right of CN System Metadata serialVersion = 10 dateSysMetadataModified = t1 end note note right of MN_repl System Metadata serialVersion = 10 dateSysMetadataModified = t1 end note activate MN MN -> Bob: dateSysMetadataModified = t1 deactivate MN Bob -> MN : updateSystemMetadata\ndateSysMetadataModified=t1 activate MN MN -> MN: check dateSysMetadataModified == t1 MN -> MN: update properties\ndateSysMetadataModified = now() note right of MN System Metadata serialVersion = 10 dateSysMetadataModified = t2 Mutable properties other than Replica entries may be updated by a user with appropriate permission. end note MN -> CN: synchronize activate CN CN -> CN: schedule update CN -> MN: ack deactivate CN MN -> Bob: ack deactivate MN ... __Potentially long delay__ ... CN -> MN : getSystemMetadata activate CN activate MN MN -> CN: systemMetadata deactivate MN CN -> CN: update properties note right of CN System Metadata serialVersion = 10 dateSysMetadataModified = t2 end note CN ->] : <<internal>> Notify System Metadata Changed note right of CN Indexing and other CN services are notified of the change end note group Update only replica nodes CN -> MN_repl: systemMetadataChanged activate MN_repl deactivate CN MN_repl -> CN: getSystemMetadata activate CN CN -> MN_repl: SystemMetadata deactivate CN note right of MN_repl System Metadata serialVersion = 10 dateSysMetadataModified = t2 On replica MNs, all mutable System Metadata properties may be updated by a CN end note MN_repl -> MN_repl: update properties deactivate MN_repl end @enduml$

Figure 2b. Sequence diagram for Use Case 42 illustrating the high level sequence of operations associated with altering system metadata of an object for version 2.x infrastructure where Member Nodes are the authoritative source for System Metadata except for replication information (for which Coordinating Nodes are authoritative). In this scenario, user Bob updates properties of System Metadata (e.g. Access Policy) for an object, and that change is propogated to copies throughout the federation.