Abstract: A method for matching subscriptions of subscribing client nodes (5) with publications of publishing client nodes (4), wherein each subscription is associated with a territory of the subscription (2B) and wherein each publication is associated with a territory of the publication (2A); wherein a geographical region (7) is divided into a plurality of tiles (1); wherein each tile (1) has an associated matching node (3) for detecting matches between publications and subscriptions in that tile; wherein a match is detected when the territory associated with a given subscription and the territory associated with a given publication overlap in that tile (1); wherein the matching node is arranged to trigger an action such as for example notifying the subscribing client node when such a match has been detected; wherein each matching node (3) is further arranged to detect when a match between a particular publication and a particular subscription will be detected in more than one tile (1); and wherein said matching no