A method in a system including a plurality of computing subsystems (104; 104-1, 104-2; 104-3) executing a set of hosted applications (106, 108, 110, 112; 106', 108'; 110', 112'), the method comprising: at each of the computing subsystems , maintaining a copy of a common routing matrix defining, for each hosted application, an identifier of a computing subsystem (104; 104-1, 104-2; 104-3) configured to host the application; at a first intra-subsystem routing component of a first one of the computing subsystems (104-1), receiving a message; determining, at the first intra-subsystem routing component (128-1), a target one of the hosted applications to process the message; identifying, according to the common routing matrix, a second one of the computing subsystems (104-2) that executes the target hosted application; in response to the identifying, providing the message and a routing indicator to a first inter-subsystem routing component (132-1) of the first computing subsystem (104-1); and at the first inter-subsystem routing component (132-1), transmitting the message to the second computing subsystem; wherein the method is characterized in that the method further comprises: at the first intra-subsystem routing component (128-1), determining that a performance attribute of an instance of a hosted application at the first computing subsystem (104-1) meets a criterion; selecting an identifier of another computing subsystem (104-2, 104-3) executing another instance of the hosted application; and updating the common routing matrix to associate the hosted application with the other computing subsystem (104-2). at each of the computing subsystems , maintaining a copy of a common routing matrix defining, for each hosted application, an identifier of a computing subsystem (104; 104-1, 104-2; 104-3) configured to host the application; at a first intra-subsystem routing component of a first one of the computing subsystems (104-1), receiving a message; determining, at the first intra-subsystem routing component (128-1), a target one of the hosted applications to process the message; identifying, according to the common routing matrix, a second one of the computing subsystems (104-2) that executes the target hosted application; in response to the identifying, providing the message and a routing indicator to a first inter-subsystem routing component (132-1) of the first computing subsystem (104-1); and at the first inter-subsystem routing component (132-1), transmitting the message to the second computing subsystem; wherein the method is characterized in that the method further comprises: at the first intra-subsystem routing component (128-1), determining that a performance attribute of an instance of a hosted application at the first computing subsystem (104-1) meets a criterion; selecting an identifier of another computing subsystem (104-2, 104-3) executing another instance of the hosted application; and updating the common routing matrix to associate the hosted application with the other computing subsystem (104-2). at the first intra-subsystem routing component (128-1), determining that a performance attribute of an instance of a hosted application at the first computing subsystem (104-1) meets a criterion; selecting an identifier of another computing subsystem (104-2, 104-3) executing another instance of the hosted application; and updating the common routing matrix to associate the hosted application with the other computing subsystem (104-2). <EOS>