Data clearing Xbus feature

This document describes the “data clearing” feature Xbus recipient nodes may implement.

If they do, they must appropriately answer the “has_clearing” API call (see the section of the Xbus documentation describing Xbus recipient API calls for details).

Feature dependencies

Xbus recipient nodes providing data clearing MUST also support:

• Immediate replies.

Database schema

A database must be available and initialized with the schema described below.

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Monitor-consumer communication

This section describes how the Xbus monitor and Xbus recipient nodes providing data clearing communicate.

For general duties, the Xbus monitor directly accesses the database announced by Xbus recipient node providing data clearing.

Certain specific operations, however, happen via requests emitted through the Xbus broker.

• Theses requests are enclosed into regular Xbus envelopes / events / items.
• The requests use the “immediate reply” feature (so a specific event type).
• The Xbus monitor is the emitter of these requests.
• Xbus recipient nodes providing data clearing are consumers of these requests.

Each data blob sent in “send_item” calls is a dictionary with an “action” key, referencing one of the following actions:

• “get_item_details”: Provide details about a data clearing item.

  Compulsory dictionary keys:

  • item_id: ID of the data clearing item to clear.

• “clear_items”: “Clear” a data clearing item. Compulsory dictionary keys:

  • item_id: ID of the data clearing item to clear.
  • values.