.TH "globus_net_manager_tutorial" 3 "Fri Nov 11 2016" "Version 0.16" "globus_net_manager" \" -*- nroff -*-
.ad l
.nh
.SH NAME
globus_net_manager_tutorial \- Net Manager Implementation Tutorial 
This example uses functionality from globus_common and globus_net_manager modules, so the headers for those must be included: 
.PP
.nf
#include "globus_common.h"
#include "globus_net_manager.h"
.fi
.PP
 To implement a network manager, define a struct \fBglobus_net_manager_s\fP containing pointers to the functions in your code that you want invoked during network events, and pass that to \fBglobus_net_manager_register()\fP\&. Applications which use the \fBContext\fP functions or the \fBGlobus XIO Net Manager Driver\fP will invoke your functions as network operations occur\&. For this example (and I would imagine most real implementations), the globus_net_manager_t is statically initialized, like this:
.PP
.PP
.nf
static
globus_net_manager_t                    globus_l_net_manager_logging = {
    "logging",
    globus_l_net_manager_logging_pre_listen,
    globus_l_net_manager_logging_post_listen,
    globus_l_net_manager_logging_end_listen,
    globus_l_net_manager_logging_pre_accept,
    globus_l_net_manager_logging_post_accept,
    globus_l_net_manager_logging_pre_connect,
    globus_l_net_manager_logging_post_connect,
    globus_l_net_manager_logging_pre_close,
    globus_l_net_manager_logging_post_close
};
.fi
.PP
 For the examples provided in this library, the \fBglobus_net_manager_s\fP is registered during module activation in a globus_extension module\&. This method makes it easy to use network managers in a shared library environment\&. This is also a good place to initialize any state that you need to retain between calls to the network manager\&.
.PP
To implement this, do the following: 
.PP
.nf
static
int
globus_l_net_manager_logging_activate(void)
{
    globus_hashtable_init(
        &globus_l_nm_logging_logfiles,
        7,
        globus_hashtable_string_hash, 
        globus_hashtable_string_keyeq);
    int rc = globus_module_activate(GLOBUS_NET_MANAGER_MODULE);
    if (rc == 0)
    {
        rc = globus_net_manager_register(
            &globus_l_net_manager_logging, 
            GlobusExtensionMyModule(globus_net_manager_logging));
    }
    return rc;
}

static
void
globus_l_logging_logfiles_destroy(void *datum)
{
    globus_l_nm_logging_logref_t        *logref = datum;
    if (logref)
    {
        free(logref->key);
        fclose(logref->handle);
        free(logref);
    }
}

static
int
globus_l_net_manager_logging_deactivate(void)
{
    globus_hashtable_destroy_all(
            &globus_l_nm_logging_logfiles,
            globus_l_logging_logfiles_destroy);

    int rc = globus_net_manager_unregister(&globus_l_net_manager_logging);
    if (rc == 0)
    {
        rc = globus_module_deactivate(GLOBUS_NET_MANAGER_MODULE);
    }
    return rc;
}

.fi
.PP
.PP
Finally, the real work of the manager is done in the functions registered in the \fBglobus_net_manager_s\fP\&. For brevity, I'll just include the pre_listen function in this tutorial\&. This function is passed the task-id associated with the operation, the transport ('tcp', 'udp', 'udt', etc) used by the network, and whatever attributes are associated with the operation\&. If we wanted to modify things before they were processed by the network, we could create a modified copy of the attributes in the pre_listen function and return them via the attr_array_out parameter\&. In this case, we simply print out the information we've received from the network stack\&.
.PP
.PP
.nf
static
globus_result_t
globus_l_net_manager_logging_pre_listen(
    struct globus_net_manager_s        *manager,
    const globus_net_manager_attr_t    *manager_attr_array,
    const char                         *task_id,
    const char                         *transport,
    const globus_net_manager_attr_t    *attr_array,
    globus_net_manager_attr_t         **attr_array_out)
{
    FILE *                              logfile;
    logfile = globus_l_net_manager_logging_get_logfile(manager_attr_array);
    globus_l_net_manager_logging_log_header(logfile, manager, task_id, transport, "pre_listen");
    globus_l_net_manager_logging_log_attrs(logfile, attr_array);
    globus_l_net_manager_logging_log_footer(logfile);
    return GLOBUS_SUCCESS;
}
/* globus_l_net_manager_logging_pre_listen() */
.fi
.PP