nanonext (version 0.10.4)

send: Send

Description

Send data over a connection (Socket, Context or Stream).

Usage

send(con, data, mode = c("serial", "raw", "next"), block = NULL)

Value

Integer exit code (zero on success).

Arguments

con

a Socket, Context or Stream.

data

an object (a vector, if mode = 'raw').

mode

[default 'serial'] one of 'serial' to send serialised R objects, 'raw' to send atomic vectors of any type as a raw byte vector, or 'next' (see 'Send Modes' section below). Alternatively, specify an integer position in the vector of choices e.g. 1L for 'serial' or 2L for 'raw' etc. For Streams, 'raw' is the only option and this argument is ignored.

block

[default NULL] which applies the connection default (see section 'Blocking' below). Specify logical TRUE to block until successful or FALSE to return immediately even if unsuccessful (e.g. if no connection is available), or else an integer value specifying the maximum time to block in milliseconds, after which the operation will time out.

Blocking

For Sockets: the default behaviour is non-blocking with block = FALSE. This will return immediately with an error if the message could not be queued for sending. Certain protocol / transport combinations may limit the number of messages that can be queued if they have yet to be received.

For Contexts: the default behaviour is blocking with block = TRUE. This will wait until the send has completed. Set to FALSE or an integer timeout to ensure that the function returns under all scenarios.

For Streams: the default behaviour is blocking with block = TRUE. This will wait until the send has completed. Set a timeout to ensure that the function returns under all scenarios. As the underlying implementation uses an asynchronous send with a wait, it is recommended to set a positive integer value for block rather than FALSE.

Send Modes

The default mode 'serial' sends serialised R objects to ensure perfect reproducibility within R. When receiving, the corresponding mode 'serial' should be used.

Mode 'raw' sends atomic vectors of any type as a raw byte vector, and must be used when interfacing with external applications or raw system sockets, where R serialization is not in use. When receiving, the mode corresponding to the vector sent should be used.

Mode 'next' sends serialised R objects, with native extensions enabled by nextmode. This allows 'refhook' functions to be registered for custom serialization and unserialization of reference objects, such as those accessed via an external pointer. When receiving, mode 'serial' should be used as 'next' sends are fully compatible.

See Also

send_aio for asynchronous send.

Examples

pub <- socket("pub", dial = "inproc://nanonext")

send(pub, data.frame(a = 1, b = 2))
send(pub, c(10.1, 20.2, 30.3), mode = "raw", block = 100)

close(pub)

req <- socket("req", listen = "inproc://nanonext")
rep <- socket("rep", dial = "inproc://nanonext")

ctx <- context(req)
send(ctx, data.frame(a = 1, b = 2), block = 100)

msg <- recv_aio(rep, timeout = 100)
send(ctx, c(1.1, 2.2, 3.3), mode = "raw", block = 100)

close(req)
close(rep)