1. A method of providing coherence between instances of data objects residing on distributed nodes of a non memory-coupled network, the method comprising: processing a data object by a node; generating platform-independent unique metadata for each instance of a so processed data object; operating a coherence protocol on said metadata; and keeping the metadata and thus the data object coherent by means of said metadata and said coherence protocol: wherein the nodes using the coherence protocol form an overlay network; and wherein there is provided a service which defines the overlay network and which allows a demand and communication of data objects between at least a part of the nodes of the overlay network.