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.TH EVS_INITIALIZE 3 2004-08-31 "corosync Man Page" "Corosync Cluster Engine Programmer's Manual"
.SH NAME
evs_initialize \- Create a new connection to the EVS service
.SH SYNOPSIS
.B #include <corosync/evs.h>
.sp
.BI "int evs_initialize(evs_handle_t *" handle ", evs_callbacks_t *" callbacks ");
.SH DESCRIPTION
The
.B evs_initialize
function is used to initialize a connection to the extended virtual synchrony API.
.PP
Each application may have several connections to the EVS API.  Each  application
uses the
.I handle
argument to uniquely identify the connection.  The
.I handle
argument is then used in other function calls to identify the connection to be used
for communication with the EVS service.
.PP
Every time an EVS event occurs, one of the callbacks specified by the argument
.I callbacks
is called.  The callback functions are described by the following type definitions:
.PP
.IP
.RS
.ne 18
.nf
.ta 4n 20n 32n
typedef void (*evs_deliver_fn_t) (
	unsigned int nodeid,
        const void *msg,
        size_t msg_len);

typedef void (*evs_confchg_fn_t) (
	unsigned int *member_list, size_t member_list_entries,
	unsigned int *left_list, size_t left_list_entries,
	unsigned int *joined_list, size_t joined_list_entries);
.ta
.fi
.RE
.IP
.PP
.PP
The
.I callbacks
argument is of the type:
.IP
.RS
.ne 18
.nf
.PP
typedef struct {
        evs_deliver_fn_t evs_deliver_fn;
        evs_confchg_fn_t evs_confchg_fn;
} evs_callbacks_t;
.ta
.fi
.RE
.IP
.PP
When a configuration change occurs or a message is to be delivered one of the callbacks
is called from the
.B evs_dispatch()
function.  If a configuration change occurs,
.I evs_confchg_fn
is called.  If a delivery of a message occurs,
.I evs_deliver_fn
is called.

.SH RETURN VALUE
This call returns the EVS_OK value if successful, otherwise an error is returned.
.PP
.SH ERRORS
The errors are undocumented.
.SH "SEE ALSO"
.BR evs_overview (8),
.BR evs_finalize (3),
.BR evs_fd_get (3),
.BR evs_dispatch (3),
.BR evs_join (3),
.BR evs_leave (3),
.BR evs_mcast_joined (3),
.BR evs_mcast_groups (3),
.BR evs_membership_get (3)
.BR evs_context_get (3)
.BR evs_context_set (3)
.PP