private void UpdateResource(CoapExchange exchange)
        {
            OpaqueResource opaqueResource = OpaqueResource.Deserialise(exchange.Request);

            if (opaqueResource == null)
            {
                Response response = Response.CreateResponse(exchange.Request, StatusCode.BadRequest);
                exchange.Respond(response);
            }
            else
            {
                Value = opaqueResource.Value;
                Response response = Response.CreateResponse(exchange.Request, StatusCode.Changed);
                exchange.Respond(response);
            }
        }