Model view replication to the Historian

Model view replication is the process of sending the model view hierarchy information to the AVEVA Historian and incorporating it into the public group namespace. Replication is initiated by ArchestrA.

Replication is a two-step process:

1. The Historian is checked to see if there is a need to update the public group namespace with information from the model view.

   Replication only occurs when the public group namespace is determined to be out of sync with the model view, in terms of objects with historized attributes and/or special types of objects, such as traceability objects.

2. The required model view changes are transmitted to the Historian and incorporated into the public namespace.

   During replication, only the object/attribute information that needs to change in the Historian is transmitted and processed, with the exception of Area objects. For example, if one object is added to a Galaxy of 1000 objects, the new object will be the only entity transmitted to the Historian and incorporated into the public group namespace. Because the amount of data for Area objects is small, all Area information is transmitted and processed, without negatively impacting performance.

ArchestrA objects and attributes that can be replicated include:

All historized attributes.

• All objects that contain historized attributes.

• All objects that contain other objects with historized attributes. This allows for representation of the complete hierarchy from the Galaxy level down to lowest-level object that has historized attributes, even if objects at intermediate levels do not have any historized attributes.

• Some special types of objects that do not typically have historized attributes, such as traceability objects. Also, their parent objects are replicated, as needed, to fill out the entire hierarchy.

Attributes that are not historized do not appear in the Historian namespace.

Replication occurs when:

• Objects with historized attributes and/or traceability objects are deployed.

• Objects with historized attributes and/or traceability objects are redeployed.

• The Historian starts up, and there was a relevant change to the model view while the Historian was offline. There may be a delay in the replication.

If you undeploy or delete an object, the changes will not be replicated until you perform a redeploy.

If replication fails to complete (for example, due to a network failure), ArchestrA will try to send the model information again during the next scan cycle, until the replication succeeds. No error message is logged to the ArchestrA Logger if replication fails; however, you can log a custom message using the "ModelViewSync" custom log flag.