MQTT Client: device_net_services Struct Reference

Accept an incominng connection. This routine creates a new communication channel for the (remote) requesting client.

Parameters:

[in]	listen	handle to listen for the incoming connection requests from the remote clients
[out]	client_ip	IP address of the connected client. This value is valid only on successful return of the routine. The place holder must provide memory to store atleast 16 bytes.
[in,out]	ip_length	Length of IP address. It is provided by the caller to declare the length of the place holder and updated by routine to indicate the length of the connected client's IP address.

Returns:

on success, a valid handle to the new connection, otherwise NULL

Close communication connection

Monitor activity on communication handles. The routine blocks for the specified period of time to monitor activity, if any, on each of the communication handle that has been provided in one or more vector sets. At the expiry of the wait time, this function must identify the handles, on which, acitvities were observed.

A particular collection of communication handles are packed as an array or in a vector and is passed to the routine. A NULL handle in the vector indicates the termination of the vector and can effectively used to account for the size of the vector.

Similarly, at end the end of the wait period, the routine must provide a vector of the handles for which activity was observed.

Parameters:

[in,out]	recv_hvec	a vector of handles which must be monitored for receive activities.
[in,out]	send_hvec	a vector of handles which must be monitored for send activities.
[in,out]	rsvd_hvec	reserved for future use.
[in]	wait_secs	time to wait and monitor activity on communication handles provided in one or more sets. If set to 0, the routine returns immediately.

Returns:

on success, the total number of handles for which activity was observed. This number can be 0, if no activity was observed on any of the provided handle in the specified time. Otherwise, -1 on error.

Listen to incoming connection from clients. This routine prepares the system to listen on the specified port for the incoming network connections from the remote clients.

Parameters:

[in]	nwconn_opts	Implementation specific construct to enumerate server address and / or connection related details
[in]	port_number	Network port number, typically, 1883 or 8883
[in]	nw_security	Information to establish a secure connection with client. Set it to NULL, if not used. Information to establish a secure connection.

Returns:

a valid handle to listening contruct, otherwise NULL

Set up a communication channel with a server or set up a local port. This routine opens up either a "connection oriented" communication channel with the specified server or set up a local configuration for "connectionless" transactions.

Parameters:

[in]	nwconn_opts	Implementation specific construct to enumerate server address and / or connection related details
[in]	server_addr	URL or IP address (string) or other server reference. For setting up a local (UDP) port, set it to NULL.
[in]	port_number	Network port number, typically, 1883 or 8883 for remote severs. For setting up a local (UDP) port, use an intended port number.
[in]	nw_security	Information to establish a secure connection with server. Set it to NULL, if not used. Information to establish a secure connection.

Returns:

a valid handle to connection, otherwise NULL

Receive data from the "connection oriented" channel. The routine blocks till the time, there is either a data that has been received from the server or the time to await data from the server has expired.

Parameters:

[in]	comm	Handle to network connection as returned by accept().
[out]	buf	place-holder to which data from network should be written into.
[in]	len	maximum length of 'buf'
[in]	wait_secs	maximum time to await data from network. If exceeded, the routine returns error with the err_timeo flag set as true.
[out]	err_timeo	if set, indicates that error is due to timeout.
[in]	ctx	reference to the MQTT connection context

Returns:

on success, number of bytes received, 0 on connection reset, otherwise -1 on error. In case, error (-1) is due to the time-out, then the implementation should set flag err_timeo as true.

Receive data on a local port sent by any network element. The routine blocks till the time, data has been received on the local port from any remote network element.

Parameters:

[in]	comm	handle to network connection as return by open().
[in]	buf	place-holder to which data from network should be written into.
[in]	len	maximum lengh of 'buf'
[out]	from_port	place-holder for the port of the sender network entity
[out]	from_ip	place-holder to retrieve the IP address of the sender network entity. The memory space must be provisioned to store atleast 16 bytes.
[in,out]	ip_len	length of IP address. It is provided by the caller to declare the length of the place holder and updated by routine to indicate the length of the remote network entity's IP address.

Returns:

on success, number of bytes received, 0 on connection reset, otherwise -1 on errir.

Send data onto the "connection oriented" network. The routine blocks till the time, the data has been copied into the network stack for dispatch on to the "connection oriented" network.

Parameters:

[in]	comm	handle to network connection as returned by open().
[in]	buf	refers to the data that is intended to be sent
[in]	len	length of the data
[in]	ctx	reference to the MQTT connection context

Returns:

on success, the number of bytes sent, 0 on connection reset, otherwise -1

Send data to particular port on the specified network element. The routine blocks till the time, the data has been copied into the network stack for dispatch to the "specified" network entity.

Parameters:

[in]	comm	handle to network connection as returned by open().
[in]	buf	refers to data that is intended to be sent
[in]	len	length of the data
[in]	dest_port	network port to which data is to be sent.
[in]	dest_ip	IP address of the entity to which data is to be sent.
[in]	ip_len	length of the destination IP address.

Returns:

on success, the number of bytes sent, 0 on connection reset, otherwise -1.

Get Time (in seconds). Provides a monotonically incrementing value of a time service in unit of seconds. The implementation should ensure that associated timer hardware or the clock module remains active through the low power states of the system. Such an arrangement ensures that MQTT Library is able to track the Keep-Alive time across the cycles of low power states. It would be typical of battery operated systems to transition to low power states during the period of inactivity or otherwise to conserve battery.

In the absence of a sustained time reference across the low power states, if the system transitions away from the active state, the MQTT Library, then may not be able to effectively monitor the Keep Alive duration.

It is the responsbililty of the implementation to manage the roll- over problem of the hardware and ensure the integrity of the time value is maintained.

Returns:

time in seconds