Nanomsg

This is a Haskell binding for the nanomsg library: http://nanomsg.org/.

There's support for (evented) blocking send and recv, a non-blocking receive, and for all the socket types and the functions you need to wire them up and tear them down again.

Most socket options are available through accessor and mutator functions. Sockets are typed, transports are not.

The documentation is adapted or quoted verbatim from the nanomsg manual, please refer to nanomsg.org for authoritative info. There's a simple code example in README.md.

Types

Socket types

data Pair

Socket for communication with exactly one peer. Each party can send messages at any time. If the peer is not available or the send buffer is full, subsequent calls will block until it’s possible to send the message.

Constructors

Pair

Instances

Receiver Pair

Sender Pair

SocketType Pair

data Req

Request socket. Pairs with Rep sockets.

The socket will resend requests automatically if there's no reply within a given time. The default timeout is 1 minute.

See also Rep, setRequestResendInterval.

Constructors

Req

Instances

Receiver Req

Sender Req

SocketType Req

data Rep

Reply socket.

See also Req.

Constructors

Rep

Instances

Receiver Rep

Sender Rep

SocketType Rep

data Pub

Publish socket. Pairs with subscribe sockets.

See also Sub.

Constructors

Pub

Instances

Sender Pub

SocketType Pub

data Sub

Subscribe socket.

Only messages that the socket is subscribed to are received. When the socket is created there are no subscriptions and thus no messages will be received.

See also Pub, subscribe and unsubscribe.

Constructors

Sub

Instances

Receiver Sub

SocketType Sub

data Surveyor

Surveyor and respondent are used to broadcast a survey to multiple locations and gather the responses.

This socket is used to send a survey. The survey is delivered to all onnected respondents. Once the query is sent, the socket can be used to receive the responses.

When the survey deadline expires, receive will throw an NNException.

See also Respondent, setSurveyorDeadline.

Constructors

Surveyor

Instances

Receiver Surveyor

Sender Surveyor

SocketType Surveyor

data Respondent

Used to respond to a survey. Survey is received using receive, response is sent using send. This socket can be connected to at most one peer.

See also Surveyor.

Constructors

Respondent

Instances

Receiver Respondent

Sender Respondent

SocketType Respondent

data Push

Push and Pull sockets fair queue messages from one processing step, load balancing them among instances of the next processing step.

See also Pull.

Constructors

Push

Instances

Sender Push

SocketType Push

data Pull

Pull socket.

See also Push.

Constructors

Pull

Instances

Receiver Pull

SocketType Pull

data Bus

Broadcasts messages from any node to all other nodes in the topology. The socket should never receives messages that it sent itself.

Constructors

Bus

Instances

Receiver Bus

Sender Bus

SocketType Bus

Other

data Socket a

Sockets are created by socket and connections are established with connect or bind.

Free sockets using close.

Instances

Eq a => Eq (Socket a)

Show a => Show (Socket a)

data Endpoint

Endpoint identifier. Created by connect or bind.

Close connections using shutdown.

Instances

Eq Endpoint

Show Endpoint

data NNException

Pretty much any error condition throws this exception.

Instances

Eq NNException

Show NNException

Exception NNException

class SocketType a

Typeclass for all sockets

Minimal complete definition

socketType

Instances

SocketType Bus

SocketType Pull

SocketType Push

SocketType Respondent

SocketType Surveyor

SocketType Sub

SocketType Pub

SocketType Rep

SocketType Req

SocketType Pair

class SocketType a => Sender a

Typeclass restricting which sockets can use the send function.

Instances

Sender Bus

Sender Push

Sender Respondent

Sender Surveyor

Sender Pub

Sender Rep

Sender Req

Sender Pair

class SocketType a => Receiver a

Typeclass for sockets that implement recv

Instances

Receiver Bus

Receiver Pull

Receiver Respondent

Receiver Surveyor

Receiver Sub

Receiver Rep

Receiver Req

Receiver Pair

Operations

General operations

socket :: SocketType a => a -> IO (Socket a)

Creates a socket. Connections are formed using bind or connect.

See also: close.

withSocket :: SocketType a => a -> (Socket a -> IO b) -> IO b

Creates a socket and runs your action with it.

E.g. collecting 10 messages:

withSocket Sub $ \sub -> do
    _ <- connect sub "tcp://localhost:5560"
    subscribe sub (C.pack "")
    replicateM 10 (recv sub)

Ensures the socket is closed when your action is done.

bind :: Socket a -> String -> IO Endpoint

Binds the socket to a local interface.

See the nanomsg documentation for specifics on transports. Note that host names do not work for tcp. Some examples are:

bind sock "tcp://*:5560"
bind sock "tcp://eth0:5560"
bind sock "tcp://127.0.0.1:5560"
bind sock "inproc://test"
bind sock "ipc:///tmp/test.ipc"

This function returns an Endpoint, which can be supplied to shutdown to remove a connection.

See also: connect, shutdown.

connect :: Socket a -> String -> IO Endpoint

Connects the socket to an endpoint.

e.g. :

connect sock "tcp://localhost:5560"
connect sock "inproc://test"

See also: bind, shutdown.

send :: Sender a => Socket a -> ByteString -> IO ()

Blocking function for sending a message

See also: recv, recv'.

recv :: Receiver a => Socket a -> IO ByteString

Blocking receive.

recv' :: Receiver a => Socket a -> IO (Maybe ByteString)

Nonblocking receive function.

subscribe :: Socket Sub -> ByteString -> IO ()

Subscribe to a given subject string.

unsubscribe :: Socket Sub -> ByteString -> IO ()

Unsubscribes from a subject.

shutdown :: Socket a -> Endpoint -> IO ()

Removes an endpoint from a socket.

See also: bind, connect.

close :: Socket a -> IO ()

Closes the socket. Any buffered inbound messages that were not yet received by the application will be discarded. The library will try to deliver any outstanding outbound messages for the time specified by NN_LINGER socket option. The call will block in the meantime.

term :: IO ()

Switches nanomsg into shutdown modus and interrupts any waiting function calls.

Socket option settings

linger :: Socket a -> IO Int

Specifies how long the socket should try to send pending outbound messages after close has been called, in milliseconds.

Negative value means infinite linger. Default value is 1000 (1 second).

setLinger :: Socket a -> Int -> IO ()

Specifies how long should the socket try to send pending outbound messages after close has been called, in milliseconds.

Negative value means infinite linger. Default value is 1000 (1 second).

sndBuf :: Socket a -> IO Int

Size of the send buffer, in bytes. To prevent blocking for messages larger than the buffer, exactly one message may be buffered in addition to the data in the send buffer.

Default value is 128kB.

setSndBuf :: Socket a -> Int -> IO ()

Size of the send buffer, in bytes. To prevent blocking for messages larger than the buffer, exactly one message may be buffered in addition to the data in the send buffer.

Default value is 128kB.

rcvBuf :: Socket a -> IO Int

Size of the receive buffer, in bytes. To prevent blocking for messages larger than the buffer, exactly one message may be buffered in addition to the data in the receive buffer.

Default value is 128kB.

setRcvBuf :: Socket a -> Int -> IO ()

Size of the receive buffer, in bytes. To prevent blocking for messages larger than the buffer, exactly one message may be buffered in addition to the data in the receive buffer.

Default value is 128kB.

reconnectInterval :: Socket a -> IO Int

For connection-based transports such as TCP, this option specifies how long to wait, in milliseconds, when connection is broken before trying to re-establish it.

Note that actual reconnect interval may be randomised to some extent to prevent severe reconnection storms.

Default value is 100 (0.1 second).

setReconnectInterval :: Socket a -> Int -> IO ()

For connection-based transports such as TCP, this option specifies how long to wait, in milliseconds, when connection is broken before trying to re-establish it.

Note that actual reconnect interval may be randomised to some extent to prevent severe reconnection storms.

Default value is 100 (0.1 second).

reconnectIntervalMax :: Socket a -> IO Int

This option is to be used only in addition to NN_RECONNECT_IVL option. It specifies maximum reconnection interval. On each reconnect attempt, the previous interval is doubled until NN_RECONNECT_IVL_MAX is reached.

Value of zero means that no exponential backoff is performed and reconnect interval is based only on NN_RECONNECT_IVL. If NN_RECONNECT_IVL_MAX is less than NN_RECONNECT_IVL, it is ignored.

Default value is 0.

setReconnectIntervalMax :: Socket a -> Int -> IO ()

This option is to be used only in addition to NN_RECONNECT_IVL option. It specifies maximum reconnection interval. On each reconnect attempt, the previous interval is doubled until NN_RECONNECT_IVL_MAX is reached.

Value of zero means that no exponential backoff is performed and reconnect interval is based only on NN_RECONNECT_IVL. If NN_RECONNECT_IVL_MAX is less than NN_RECONNECT_IVL, it is ignored.

Default value is 0.

sndPrio :: Socket a -> IO Int

Sets outbound priority for endpoints subsequently added to the socket. This option has no effect on socket types that send messages to all the peers. However, if the socket type sends each message to a single peer (or a limited set of peers), peers with high priority take precedence over peers with low priority.

Highest priority is 1, lowest priority is 16. Default value is 8.

setSndPrio :: Socket a -> Int -> IO ()

Sets outbound priority for endpoints subsequently added to the socket. This option has no effect on socket types that send messages to all the peers. However, if the socket type sends each message to a single peer (or a limited set of peers), peers with high priority take precedence over peers with low priority.

Highest priority is 1, lowest priority is 16. Default value is 8.

ipv4Only :: Socket a -> IO Int

If set to 1, only IPv4 addresses are used. If set to 0, both IPv4 and IPv6 addresses are used.

Default value is 1.

setIpv4Only :: Socket a -> Int -> IO ()

If set to 1, only IPv4 addresses are used. If set to 0, both IPv4 and IPv6 addresses are used.

Default value is 1.

requestResendInterval :: Socket Req -> IO Int

This option is defined on the full REQ socket. If reply is not received in specified amount of milliseconds, the request will be automatically resent.

Default value is 60000 (1 minute).

setRequestResendInterval :: Socket Req -> Int -> IO ()

This option is defined on the full REQ socket. If reply is not received in specified amount of milliseconds, the request will be automatically resent.

Default value is 60000 (1 minute).

surveyorDeadline :: Socket Surveyor -> IO Int

Get timeout for Surveyor sockets

setSurveyorDeadline :: Socket Surveyor -> Int -> IO ()

Set timeout for Surveyor sockets

tcpNoDelay :: Socket a -> IO Int

This option, when set to 1, disables Nagle's algorithm.

Default value is 0.

setTcpNoDelay :: Socket a -> Int -> IO ()

This option, when set to 1, disables Nagle's algorithm.

Default value is 0.