Hi Andrew,
Sure. In the XML Time Machine, the XDM (data model) is augmented with an additional dimension: time. This means that a node (in the XDM spacetime) is identified with two coordinates:
1. a reference URI
2. a version URI
The reference URI corresponds to the concept of node identity in the XDM specification. A node that evolves according to the XQuery Update specification (meaning that its accessors are modified, e.g., children added/removed, node renamed) corresponds in the XML Time Machine to a series of nodes that share the same reference URI, but have different version URIs. Such a series of nodes is called a node timeline.
Using time axes means navigating within a timeline. Given a node in version 10, it is possible to get the "same" node in version 5. The concept of node identity in the XDM specification allows to give a meaning to "same".
Does it make sense?
Kind regards,
Ghislain
On Sep 19, 2011, at 3:38 PM, Andrew Welch wrote:
>> Also, the XQuery and XPath Data Model has the concept of node identity, of which the versioning system can keep track.
>
> Can you expand on that a little - how does node indentity in the XDM
> help version control?
>
>
> --
> Andrew Welch
> http://andrewjwelch.com
