Diff: M2XStreamClient.h

Revision:

5:ea68c8980ad8

Child:

6:e6d66d99dd6f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/M2XStreamClient.h	Thu Oct 24 12:22:33 2013 +0000
@@ -0,0 +1,128 @@
+#ifndef M2XStreamClient_h
+#define M2XStreamClient_h
+
+#define MIN(a, b) (((a) > (b))?(b):(a))
+
+#include "mbed.h"
+#include "Client.h"
+#include "Utility.h"
+
+#include "NullPrint.h"
+
+static const int E_OK = 0;
+static const int E_NOCONNECTION = -1;
+static const int E_DISCONNECTED = -2;
+static const int E_NOTREACHABLE = -3;
+static const int E_INVALID = -4;
+static const int E_JSON_INVALID = -5;
+
+typedef void (*stream_value_read_callback)(const char* at,
+                                           const char* value,
+                                           int index,
+                                           void* context);
+
+typedef void (*location_read_callback)(const char* name,
+                                       double latitude,
+                                       double longitude,
+                                       double elevation,
+                                       const char* timestamp,
+                                       int index,
+                                       void* context);
+
+class M2XStreamClient {
+public:
+  static const char* kDefaultM2XHost;
+  static const int kDefaultM2XPort = 80;
+
+  M2XStreamClient(Client* client,
+                  const char* key,
+                  const char* host = kDefaultM2XHost,
+                  int port = kDefaultM2XPort);
+
+  // Update data stream, returns the HTTP status code
+  int send(const char* feedId, const char* streamName, double value);
+  int send(const char* feedId, const char* streamName, long value);
+  int send(const char* feedId, const char* streamName, int value);
+  int send(const char* feedId, const char* streamName, const char* value);
+
+  // Receive values for a particular data stream. Since memory is
+  // very limited on an Arduino, we cannot parse and get all the
+  // data points in memory. Instead, we use callbacks here: whenever
+  // a new data point is parsed, we call the callback using the values,
+  // after that, the values will be thrown away to make space for new
+  // values.
+  // Note that you can also pass in a user-specified context in this
+  // function, this context will be passed to the callback function
+  // each time we get a data point.
+  // For each data point, the callback will be called once. The HTTP
+  // status code will be returned. And the content is only parsed when
+  // the status code is 200.
+  int receive(const char* feedId, const char* streamName,
+              stream_value_read_callback callback, void* context);
+
+  // Update datasource location
+  // NOTE: On an Arduino Uno and other ATMEGA based boards, double has
+  // 4-byte (32 bits) precision, which is the same as float. So there's
+  // no natural double-precision floating number on these boards. With
+  // a float value, we have a precision of roughly 7 digits, that means
+  // either 5 or 6 digits after the floating point. According to wikipedia,
+  // a difference of 0.00001 will give us ~1.1132m distance. If this
+  // precision is good for you, you can use the double-version we provided
+  // here. Otherwise, you may need to use the string-version and do the
+  // actual conversion by yourselves.
+  // However, with an Arduino Due board, double has 8-bytes (64 bits)
+  // precision, which means you are free to use the double-version only
+  // without any precision problems.
+  // Returned value is the http status code.
+  int updateLocation(const char* feedId, const char* name,
+                     double latitude, double longitude, double elevation);
+  int updateLocation(const char* feedId, const char* name,
+                     const char* latitude, const char* longitude,
+                     const char* elevation);
+
+  // Read location information for a feed. Also used callback to process
+  // data points for memory reasons. The HTTP status code is returned,
+  // response is only parsed when the HTTP status code is 200
+  int readLocation(const char* feedId, location_read_callback callback,
+                   void* context);
+private:
+  Client* _client;
+  const char* _key;
+  const char* _host;
+  int _port;
+  NullPrint _null_print;
+
+  // Writes the HTTP header part for updating a stream value
+  void writeSendHeader(const char* feedId,
+                       const char* streamName,
+                       int contentLength);
+  // Writes HTTP header lines including M2X key, host, content
+  // type and content length(if the body exists)
+  void writeHttpHeader(int contentLength);
+  // Parses HTTP response header and return the content length.
+  // Note that this function does not parse all http headers, as long
+  // as the content length is found, this function will return
+  int readContentLength();
+  // Skips all HTTP response header part. Return minus value in case
+  // the connection is closed before we got all headers
+  int skipHttpHeader();
+  // Parses and returns the HTTP status code, note this function will
+  // return immediately once it gets the status code
+  int readStatusCode(bool closeClient);
+  // Waits for a certain string pattern in the HTTP header, and returns
+  // once the pattern is found. In the pattern, you can use '*' to denote
+  // any character
+  int waitForString(const char* str);
+  // Closes the connection
+  void close();
+  // Parses JSON response of stream value API, and calls callback function
+  // once we get a data point
+  int readStreamValue(stream_value_read_callback callback, void* context);
+  // Parses JSON response of location API, and calls callback function once
+  // we get a data point
+  int readLocation(location_read_callback callback, void* context);
+};
+
+#endif  /* M2XStreamClient_h */
+
+