Diff: TimeService.h

Revision:

16:7903152de19f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/TimeService.h	Mon Dec 28 12:48:19 2015 +0000
@@ -0,0 +1,40 @@
+#ifndef TimeService_h
+#define TimeService_h
+
+class M2XStreamClient;
+
+// A ISO8601 timestamp generation service for M2X.
+// It uses the Time API provided by the M2X server to initialize
+// clock, then uses millis() function provided by Arduino to calculate
+// time advancements so as to reduce API query times.
+//
+// Right now, this service only works with 32-bit timestamp, meaning that
+// this service won't work after 03:14:07 UTC on 19 January 2038. However,
+// a similar service that uses 64-bit timestamp can be implemented following
+// the logic here.
+class TimeService {
+public:
+  TimeService(M2XStreamClient* client);
+
+  // Initialize the time service. Notice the TimeService instance is only
+  // working after calling this function successfully.
+  int init();
+
+  // Reset the internal recorded time by calling M2X Time API again. Normally,
+  // you don't need to call this manually. TimeService will handle Arduino clock
+  // overflow automatically
+  int reset();
+
+  // Fills ISO8601 formatted timestamp into the buffer provided. +length+ should
+  // contains the maximum supported length of the buffer when calling. For now,
+  // the buffer should be able to store 25 characters for a full ISO8601 formatted
+  // timestamp, otherwise, an error will be returned.
+  int getTimestamp(char* buffer, int* length);
+private:
+  M2XStreamClient* _client;
+  int32_t _server_timestamp;
+  uint32_t _local_last_milli;
+  Timer _timer;
+};
+
+#endif  /* TimeService_h */