A machine-to-machine (M2M) apparatus (90, 161) for cross-resource subscription, the M2M apparatus comprising: a processor; and a memory (82, 93) coupled with the processor, the memory comprising executable instructions that when executed by the processor cause the processor to effectuate operations comprising: receiving, from a subscriber M2M entity, a message for a cross-resource subscription, wherein the message is indicative of a request, by a remote M2M device, for a subscription and indicates a time window and a type of the time window, the type of the time window being one of a periodic time window type and a sliding time window type, wherein the subscription is for the remote M2M device to be notified that a plurality of target resources hosted on one or more resource hosts different from the M2M apparatus meet criteria within the time window indicated by the message; based on the message, determining that the remote M2M device has privilege to access the target resources; and based on having the privilege to access the target resources, generating a local subscription resource hosted on the M2M apparatus for the cross-resource subscription of the plurality of target resources, the local subscription resource being identifiable by an identifier to enable the subscriber M2M entity to update or delete the cross-resource subscription for the plurality of target resources based on the identifier of the local subscription resource. a processor; and a memory (82, 93) coupled with the processor, the memory comprising executable instructions that when executed by the processor cause the processor to effectuate operations comprising: receiving, from a subscriber M2M entity, a message for a cross-resource subscription, wherein the message is indicative of a request, by a remote M2M device, for a subscription and indicates a time window and a type of the time window, the type of the time window being one of a periodic time window type and a sliding time window type, wherein the subscription is for the remote M2M device to be notified that a plurality of target resources hosted on one or more resource hosts different from the M2M apparatus meet criteria within the time window indicated by the message; based on the message, determining that the remote M2M device has privilege to access the target resources; and based on having the privilege to access the target resources, generating a local subscription resource hosted on the M2M apparatus for the cross-resource subscription of the plurality of target resources, the local subscription resource being identifiable by an identifier to enable the subscriber M2M entity to update or delete the cross-resource subscription for the plurality of target resources based on the identifier of the local subscription resource. receiving, from a subscriber M2M entity, a message for a cross-resource subscription, wherein the message is indicative of a request, by a remote M2M device, for a subscription and indicates a time window and a type of the time window, the type of the time window being one of a periodic time window type and a sliding time window type, wherein the subscription is for the remote M2M device to be notified that a plurality of target resources hosted on one or more resource hosts different from the M2M apparatus meet criteria within the time window indicated by the message; wherein the message is indicative of a request, by a remote M2M device, for a subscription and indicates a time window and a type of the time window, the type of the time window being one of a periodic time window type and a sliding time window type, wherein the subscription is for the remote M2M device to be notified that a plurality of target resources hosted on one or more resource hosts different from the M2M apparatus meet criteria within the time window indicated by the message; based on the message, determining that the remote M2M device has privilege to access the target resources; and based on having the privilege to access the target resources, generating a local subscription resource hosted on the M2M apparatus for the cross-resource subscription of the plurality of target resources, the local subscription resource being identifiable by an identifier to enable the subscriber M2M entity to update or delete the cross-resource subscription for the plurality of target resources based on the identifier of the local subscription resource.