Reference Manual

Request Response
AT+HttpGetHeader=[index],[option],
[format], [length]
+HttpGetHeader:[index],[format],
[length],[data]
Arguments:
index - client handle index - client handle
option - see table 74 format - data format(0=Bin,1=Base64)
format - data format(0=Bin,1=Base64) length - actual data length
length - max data legth data - value
Table 73: AT+HttpGetHeader
Header options
res_age, res_allow, res_cache_control, res_connection, res_content_encoding,
res_content_language, res_content_length, res_content_location, res_content_range,
res_content_type, res_date, res_etag, res_expires, res_last_modified, res_location,
res_proxy_auth, res_retry_after, res_server, res_set_cookie, res_trailer,
res_tx_encoding, res_upgrade, res_vary, res_via, res_www_auth, res_warning,
req_accept, req_accept_charset, req_accept_encoding, req_accept_language,
req_allow, req_auth, req_cache_control, req_connection, req_content_encoding,
req_content_language, req_content_location, req_content_type, req_cookie,
req_date, req_expect, req_forwarded, req_from, req_host, req_if_match,
req_if_modified_since, req_if_none_match, req_if_range, req_if_unmodified_since,
req_origin, req_proxy_auth, req_range, req_te, req_tx_encoding, req_upgrade,
req_user_agent, req_via, req_warning
Table 74: HTTP header options
The module allocates memory for user data read depending on the length field
specified in the above commands. If not enough memory can be allocated an
error is returned. We recommend to use a maximum length field of 1460.
8.6.4. MQTT client
MQTT (Message Queue Telemetry Transport) is a machine-to-machine (M2M) connectivity
protocol based on publish/subscribe transport mechanism. Features like light-weight, low
network bandwidth, scalability makes it ideal for low-power, low-bandwidth IoT applications.
A MQTT network consists of a broker connected to multiple clients. Clients can each sub-
scribe to several topics or publish on any topic. The broker on the other hand is responsible
for receiving a published topic and pushing it to all the subscribed nodes.
Calypso offers AT commands to create an MQTT client, subscribe as well as publish topics.
The following section describes these commands.
Calypso reference manual version 1.2 © April 2019
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