Chicken Scheme bindings for the lightweight ZMQ-alternative, nanomsg. There exists Chicken ZMQ bindings, but this turned out to be a little troublesome with zmq_poll blocking other srfi-18 threads.
Nanomsg is smaller, written in C, has a simplified API (sockets are simple ints), no multipart messages, and has explicit support for poll on a socket's recv file-descriptor, which integrates well with Chicken Scheme.
This egg requires nanomsg-1.0.0 or higher.
[procedure] (nn-socket protocol [domain])
Create a nanomsg
socket. Protocol can be any of the symbols pair, pub, sub,
pull, push, req, rep, surveyor, respondent or
bus. Domain can be the symbol sp or sp-raw, and defaults to
sp. The returned socket is automatically closed with nn-close when
it is garbage-collected.
[procedure] (nn-socket* protocol [domain])
Just like nn-socket, but does not attach a finalizer on the
returned socket object. You must manually call nn-close on the
socket after use.
[procedure] (nn-bind socket address)
Binds nanomsg socket to
address, where address is a string of the form
"ipc:///var/ipc/music.nn.pair" or "tcp://0.0.0.0:10080". If the
nn-library can't parse the address string, it throws an "Illegal
argument" error.
[procedure] (nn-connect socket address)
Connects nanomsg socket
socket to address.
[procedure] (nn-subscribe socket prefix)
Set the NN_SUB_SUBSCRIBE
option on socket which will make the socket receive to all messages
that start with prefix.
Note that if this is never called,
(nn-sock 'sub)sockets will never receive anything.
[procedure] (nn-send socket msg)
Send a message on socket, using the socket's semantics. msg must
be a string. This will not block other srfi-18 threads. Returns the
number of bytes sent.
[procedure] (nn-send* socket msg flags)
Like nn-send, but may block other srfi-18 threads when flags is
0. flags may be nn/dontwait in which case nn-send* always
returns immediately, and returns #f is the operation would block
(number of bytes otherwise).
[procedure] (nn-recv socket)
Receive a message from socket. This blocks until a message is received from nanomsg, but it does not block other srfi-18 threads. It always returns a string. An error is thrown if the socket is in an illegal state.
Note that memory is copied from the nanomsg buffer into a new scheme string.
[procedure] (nn-recv* socket flags)
Receive a message from socket. This will block other srfi-18 threads,
unless the nn/dontwait flag is specified, in which case nn-recv*
will exit immediately with either a message as a string or #f (for
EAGAIN). An error is thrown if socket is in an illegal state.
Note that this can be combined with
(nn-socket-rcvfd socket)for custom polling.
[procedure] (nn-close socket)
Explicitly close socket. This is normally not needed as this is done
in the socket's finalizer.
[procedure] (nn-shutdown socket endpoint)
Removed endpoint from socket.
See nn_shutdown.
[procedure] (nn-get-statistic socket statistic)
Retrieve a statistic from socket. statistic may be any one of
these symbols: established-connections accepted-connections
dropped-connections broken-connections connect-errors
bind-errors accept-errors current-connections
inprogress-connections current-ep-errors messages-sent
messages-received bytes-sent bytes-received
current-snd-priority. See
nn_get_statistic.
[procedure] (nn-socket-name socket)
[procedure] (nn-socket-linger socket)
[procedure] (nn-socket-rcvtimeo socket)
[procedure] (nn-socket-sndtimeo socket)
[procedure] (nn-socket-rcvbuf socket)
[procedure] (nn-socket-sndbuf socket)
[procedure] (nn-socket-sndfd socket)
[procedure] (nn-socket-rcvfd socket)
[procedure] (nn-socket-protocol socket)
[procedure] (nn-socket-domain socket)
[procedure] (nn-socket-maxttl socket)
[procedure] (nn-socket-rcvmaxsize socket)
[procedure] (nn-socket-rcvprio socket)
[procedure] (nn-socket-sndprio socket)
[procedure] (nn-socket-reconnect-ivl-max socket)
[procedure] (nn-socket-reconnect-ivl socket)
[procedure] (nn-socket-ipv4only socket)
[procedure] (nn-req-socket-resend-ivl socket)
Retrieve the socket option associated with socket. Most of these
also provide setters so that you can, for example, can do (set! (nn-socket-name s) "foo").
For other socket options, try nn-getsockopt/string,
nn-getsockopt/int, nn-setsockopt/string and nn-setsockopt/int.
These bindings to nanomsg 1.0.0 should be fairly complete, the only
missing functionality is the control messages (nn_recvmsg,
nn_sendmsg and nn_cmsg). Also, note that the egg hasn't undergode
rigerous testing in the field yet.
;; test.scm
(import nanomsg)
(define s (nn-socket 'rep))
(nn-bind s "tcp://127.0.0.1:22022")
(let loop ((n 0))
(nn-send s (conc (nn-recv s) " " n))
(loop (add1 n)))
(nn-close s)then test with the brilliant nanocat util that comes with nanomsg:
$ csi -s test.scm &
$ nanocat --req -l22022 -D"bottles of beer:" -A --interval 1