XML Memory and Change Tracking

Robin La Fontaine robin.lafontaine AT deltaxml.com

Summary

XML data is constantly changing - we are proposing a standard way to record the changes and encapsulate these in the XML document itself, providing a 'memory' of previous states or change tracking.

1. Introduction

What do we mean by 'XML memory'?

- capture changes to an XML document within the document

- provide a memory of changes

- good for XML data and XML documents

What are the use cases?

- change tracking in documents using XML

- memory for data files in XML to roll-back or view changes

- executable audit trails

Why have a standard?

- easier for schema designers to access a standard than design bespoke change tracking

- easier for XML processors to understand generic way to handle memory/change tracking

- easier for XML editors to implement one way to handle change tracking

2. Overview of Proposal

(See [1] for further details)

Some design principles

- easy to get latest version: just ignore delta namespaces

- validation is for original schema, no need to validate changes

- capability to group changes

- capability to 'order' changes for dependencies

- Level 1 for basic, simple changes; Level 2 for more advanced changes preserving content

Level 1: intuitive and easy, not optimal

- add/delete elements and text

- add/delete/modify attributes

- sandbox demonstration here [2]

Level 2: allows structure changes round content

- add or remove elements without touching content

- split and merge elements

- move elements

Representations

- markup as normative encoding

- Processing Instruction encapsulation for XML editors

- external representation for updates and collaboration?

3. Questions for discussion

- what are other/new/possible use cases for this standard?

- what are implications for browsers?