After all this discussion of resources, it's worth bring ourselves back to Earth with this rather basic question.
The short answer is: the hosting service. Whoever owns the hosting service chooses the resources when they start it up.
Here is how it works in Jtrix.org's implementation... On top of Jtrix.org's node implementation, Nodality, is the program jnode which takes a Nodality node and gives it networking communications. Jnode takes parameters to configure resources. An additional layer, hospitality, takes one or more Jnodes, allows them to work as a group and adds a hosting service, meaning that it allows the resources on the Jnodes to be offered to third parties.
Nik Silver 2002-03-09