A device in a networked system, the device being a computer subsystem, comprising: one or more services (210A, 210B) executing in the device, each service including a port identifiable by an identifier that includes a uniform resource identifier (210A-1, 210B-1) and a unilateral contract (210A-2, 210B-2); the unilateral contract includes: one or more behavior sentences that describe the one or more behaviors of the service; wherein the unilateral contract is expressed in a language specifying an order of messages which flow in and out of the service; wherein the unilateral contract is accepted by a second service by complying with and performing the behaviors as expressed by behavior sentences of the unilateral contract; wherein the unilateral contract regulates the service by specifying attaching behavioral conditions to files to govern access control; wherein the device is a display and the one or more services is a display service; and wherein the display service includes a cursor shape service for describing the shape on an on-screen cursor, the cursor shape service including a port identifiable by an identifier that includes a uniform resource identifier and a unilateral contract for describing one or more behaviors of the cursor shape service; or wherein the display service includes a cursor position service for describing the position of an on-screen cursor, the cursor position service including a port identifiable by an identifier that includes a uniform resource identifier and a unilateral contract for describing one or more behaviors of the cursor position service. one or more services (210A, 210B) executing in the device, each service including a port identifiable by an identifier that includes a uniform resource identifier (210A-1, 210B-1) and a unilateral contract (210A-2, 210B-2); the unilateral contract includes: one or more behavior sentences that describe the one or more behaviors of the service; wherein the unilateral contract is expressed in a language specifying an order of messages which flow in and out of the service; wherein the unilateral contract is accepted by a second service by complying with and performing the behaviors as expressed by behavior sentences of the unilateral contract; wherein the unilateral contract regulates the service by specifying attaching behavioral conditions to files to govern access control; wherein the device is a display and the one or more services is a display service; and wherein the display service includes a cursor shape service for describing the shape on an on-screen cursor, the cursor shape service including a port identifiable by an identifier that includes a uniform resource identifier and a unilateral contract for describing one or more behaviors of the cursor shape service; or wherein the display service includes a cursor position service for describing the position of an on-screen cursor, the cursor position service including a port identifiable by an identifier that includes a uniform resource identifier and a unilateral contract for describing one or more behaviors of the cursor position service. one or more behavior sentences that describe the one or more behaviors of the service; wherein the unilateral contract is expressed in a language specifying an order of messages which flow in and out of the service; wherein the unilateral contract is accepted by a second service by complying with and performing the behaviors as expressed by behavior sentences of the unilateral contract; wherein the unilateral contract regulates the service by specifying attaching behavioral conditions to files to govern access control; wherein the device is a display and the one or more services is a display service; and wherein the display service includes a cursor shape service for describing the shape on an on-screen cursor, the cursor shape service including a port identifiable by an identifier that includes a uniform resource identifier and a unilateral contract for describing one or more behaviors of the cursor shape service; or wherein the display service includes a cursor position service for describing the position of an on-screen cursor, the cursor position service including a port identifiable by an identifier that includes a uniform resource identifier and a unilateral contract for describing one or more behaviors of the cursor position service.