A Constrained Application Protocol, CoAP, client (1002, 1102, 1202, 1302, 1700, 1800, 1900) comprising processing circuitry configured to: send to a CoAP server (1004, 1104, 1204, 1304, 1400, 1500, 1600) a request for information about a resource, the request for information comprising: a CoAP Observe registration comprising an Observe option; a time period option, wherein the time period option comprises a first time period value that indicates a period of time prior to the sending of the request for information over which information about the resource is requested, wherein the information about the resource comprises at least one representation of the resource over the period of time; and a time interval option, wherein the time interval option comprises a first time interval value that indicates a minimum period of time that is to separate successive representations of the resource to be provided in response to the request for information, and a second time interval value, wherein the second time interval value indicates a minimum period of time to elapse between successive Observe notifications to be provided by the CoAP server in response to the Observe registration; receive a response to the request for information send to a CoAP server (1004, 1104, 1204, 1304, 1400, 1500, 1600) a request for information about a resource, the request for information comprising: a CoAP Observe registration comprising an Observe option; a time period option, wherein the time period option comprises a first time period value that indicates a period of time prior to the sending of the request for information over which information about the resource is requested, wherein the information about the resource comprises at least one representation of the resource over the period of time; and a time interval option, wherein the time interval option comprises a first time interval value that indicates a minimum period of time that is to separate successive representations of the resource to be provided in response to the request for information, and a second time interval value, wherein the second time interval value indicates a minimum period of time to elapse between successive Observe notifications to be provided by the CoAP server in response to the Observe registration; a CoAP Observe registration comprising an Observe option; a time period option, wherein the time period option comprises a first time period value that indicates a period of time prior to the sending of the request for information over which information about the resource is requested, wherein the information about the resource comprises at least one representation of the resource over the period of time; and a time interval option, wherein the time interval option comprises a first time interval value that indicates a minimum period of time that is to separate successive representations of the resource to be provided in response to the request for information, and a second time interval value, wherein the second time interval value indicates a minimum period of time to elapse between successive Observe notifications to be provided by the CoAP server in response to the Observe registration; receive a response to the request for information