NAME

SYNOPSIS

void coap_context_set_keepalive(coap_context_t *context, unsigned int seconds);

For specific (D)TLS library support, link with -lcoap-3-notls, -lcoap-3-gnutls, -lcoap-3-openssl, -lcoap-3-mbedtls or -lcoap-3-tinydtls. Otherwise, link with -lcoap-3 to get the default (D)TLS library support.

DESCRIPTION

For UDP/DTLS, this is done with the confirmable CoAP (0.00) Ping packet, which solicits a CoAP RST response. For TCP/TLS, this is done with CoAP (7.02) Ping packet, which solicits a CoAP (7.03) Pong response, all handled by libcoap.

The coap_context_set_keepalive() function needs to be called to update the context with the keepalive for idle traffic timeout of seconds. If seconds is set to 0 (the default), then the sending of keepalives is disabled. Any sessions created from this context will use the same seconds value to determine whether a keepalive "ping" is to be sent out or not.

Applications can track the usage of the receipt of "pings" and receipt of "responses" by defining the respective handlers to use by using coap_register_ping_handler() and coap_register_pong_handler().

If the keepalive fails to solicit a response, then this can be tracked by defining the handler to use by using coap_register_nack_handler() which will be called with a reason of COAP_NACK_TOO_MANY_RETRIES.

NOTE: coap_context_set_keepalive() is supported by both the CoAP client and CoAP server.

SEE ALSO

FURTHER INFORMATION

"RFC8323: CoAP (Constrained Application Protocol) over TCP, TLS, and WebSockets"

BUGS

AUTHORS