Manual Reference Pages - SP_MULTICAST (3)
SP_multicast, SP_scat_multicast, SP_multigroup_multicast, SP_multigroup_scat_multicast - Multicast message to groups
int SP_multicast( mailbox mbox, service service_type, const char *group, int16 mess_type, int mess_len, const char *mess);
int SP_scat_multicast( mailbox mbox, service service_type, const char *group, int16 mess_type, const scatter scat_mess);
int SP_multigroup_multicast( mailbox mbox, service service_type, int num_groups, const char groups[MAX_GROUP_NAME], int16 mess_type, int mess_len, const char *mess);
int SP_multigroup_scat_multicast( mailbox mbox, service service_type, int num_groups, const char groups[MAX_GROUP_NAME], int16 mess_type, const scatter scat_mess);
SP_multicast and its variants all can multicast send a message to one or more groups. The
message is sent on a particular connection and is marked as having come from the
connection who sent it.
service_type is a type field that should be set to the service this message
requires. The valid flags for messages are:
can be bit ORed with other flags like SELF_DISCARD
if desired. Currently SELF_DISCARD is the only additional flag.
SP_scat_multicast versions are being used then only one group can be sent to. So the
group string should include the name of the group to send to. If a multigroup
varient is being used then the groups are specified by the
num_groups integer and the array of group names called
groups representing all the groups the message should be sent to.
Each group has a string name of no
more then MAX_GROUP_NAME chars. The array should have
at least as many group names as the num_groups parameter
The Spread system will only
send the message once but will deliver it to all connections which
have joined at least one of the groups listed.
mess_type This is a SHORT int (16 bits) which can be used by the
application arbitrarily. The intent is that it could be used
to NAME different kinds of data messages so they can be
differentiated without looking into the body of the message.
will be endian corrected before receiving.
If the non-scatter varients are being used then a single buffer is
passed to the multicast call specifying the full message to be sent.
mess_len field gives the length in bytes of the message. While the
mess field is a pointer to the buffer containing the message.
For a scatter call both of these are replaced with one pointer,
scat_mess, to a scatter structure, which is just like an iovec. This allows
messages made up of several parts to be sent without an extra copy
on systems which support scatter-gather.
Returns the number of bytes sent
on success or one of the following errors ( < 0 ):
mbox given to multicast on was illegal.
The message had an illegal structure, like a scatter not filled out correctly.
During communication to send the message errors occured
and the send could not be completed.
Yair Amir <email@example.com>
Jonathan Stanton <firstname.lastname@example.org>
|SPREAD ||SP_MULTICAST (3) ||JULY 1998 |
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