Is there any PHP (+ xml?) equivalent (or similar) for this awesome .net library?

[Firefox Wins]

"SSE is an XML micro-format and corresponding sync algorithm that can be embedded in RSS or Atom feeds to allow for two-way synchronization among peers. More important: the algorithm allows for mesh-style synchronization between nodes, with no concept of a "master" copy. This can be game-changing for data-exchange and app-level data interop. But only the future will tell..."

Simple Sharing Extensions (SSE) for .NET
http://sse.codeplex.com/
^^^

What I'm looking for does *not* even need any RSS/Atom/xml; I'm interested in the two-way sync with no concept of a "master" copy.

• Has anyone ever seen a way to do that with PHP?
  

Thank you.