The network.spread system provides Common Lisp bindings for the
client library of the Spread group communication system.
When using Spread, the first step usually consists in establishing a connection to the Spread daemon. The following example demonstrates this for a situation in which the Spread daemon is running on the local machine and listening on port 4803 (the default port):
(defvar *connection* (network.spread:connect "4803"))After a connection has been established, data can be sent and received. However, in order to receive data, it is necessary to join the Spread group to which messages are sent. In the following code, the previously created connection joins a Spread group called =”mygroup”=. The number of groups a given connection is a member of is evident from the printed representation of the connection instance.
(network.spread:join *connection* "mygroup")After joining one ore more groups, messages can be received:
(network.spread:receive *connection* :block? nil)Consing can be avoided by receiving into a previously allocated buffer:
(defvar *buffer* (nibbles:make-octet-vector 10000))
(network.spread:receive-into *connection* *buffer*)To send data to receivers in a Spread group, the generic functions
network.spread:send and network.spread:send-bytes are used (the
delegates the actual work to the latter):
(network.spread:send *connection* "mygroup" "mymessage")Note that it is not necessary to join a Spread group in order to send messages to that group.
It is possible to send a single message to multiple groups:
(network.spread:send *connection* '("mygroup" "othergroup") "mymessage")