This is an example of BLE GATT Client, which receives broadcast data from BLE_Server_BME280 ( a GATT server) , then transfers values up to mbed Device Connector (cloud).

Please refer details about BLEClient_mbedDevConn below. https://github.com/soramame21/BLEClient_mbedDevConn

The location of required BLE GATT server, BLE_Server_BME280, is at here. https://developer.mbed.org/users/edamame22/code/BLE_Server_BME280/

Revision:
0:29983394c6b6
diff -r 000000000000 -r 29983394c6b6 mbed-client/source/m2mstringbufferbase.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-client/source/m2mstringbufferbase.cpp	Thu Apr 13 04:48:11 2017 +0000
@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2016 ARM Limited. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "mbed-client/m2mstringbufferbase.h"
+
+#include "mbed-client/m2mstring.h"
+
+#include <assert.h>
+#include <string.h>
+
+
+bool StringBufferBase::ensure_space(size_t max_size, size_t required_size) const
+{
+    const size_t space_left = max_size - _curr_size;
+
+    bool space_available = false;
+
+    if (required_size <= space_left) {
+
+        space_available = true;
+    }
+    return space_available;
+}
+
+bool StringBufferBase::append(char *buff, size_t max_size, char data)
+{
+    bool space_available = ensure_space(max_size, 1 + 1); // there must be space for trailing zero too
+    if (space_available) {
+        buff[_curr_size++] = data;
+        buff[_curr_size] = '\0';
+        assert(_curr_size < max_size);
+    }
+    return space_available;
+}
+
+bool StringBufferBase::append(char *buff, size_t max_size, const char *data)
+{
+
+    const size_t string_len = strlen(data);
+    bool space_available = ensure_space(max_size, string_len + 1);
+    if (space_available) {
+        memcpy(buff + _curr_size, data, string_len + 1); // copy the zero terminator too
+        _curr_size += string_len;
+        assert(_curr_size < max_size);
+    }
+    return space_available;
+}
+
+bool StringBufferBase::append(char *buff, size_t max_size, const char *data, size_t data_len)
+{
+    bool space_available = true;
+    if (data_len > 0) {
+        space_available = ensure_space(max_size, data_len + 1);
+        if (space_available) {
+            memcpy(buff + _curr_size, data, data_len);
+            _curr_size += data_len;
+            // Todo: should the code actually check, if the data already contained zero or not?
+            buff[_curr_size] = '\0';
+            assert(_curr_size < max_size);
+        }
+    }
+    return space_available;
+}
+
+bool StringBufferBase::append_int(char *buff, size_t max_size, uint16_t data)
+{
+    // max len of "-9223372036854775808" plus zero termination
+    char conv_buff[20+1];
+
+    // re-use the String's functionality, a more optimal version would use snprintf() or int size specific converter
+    int len = m2m::itoa_c(data, conv_buff);
+
+    return append(buff, max_size, conv_buff, len);
+}
+
+int StringBufferBase::find_last_of(const char *buff, char search_char) const
+{
+    int last_index = -1;
+    // search from the end of string, return upon first found matching char
+    for (int index = _curr_size; index >= 0; index--) {
+        if (buff[index] == search_char) {
+            last_index = index;
+            break;
+        }
+    }
+
+    return last_index;
+}