The Storyboard IO plugin provides the capability to set application variable values using the Storyboard IO API, allowing external client programs to change data dynamically.

Clients can use the gre_io_add_mdata() function to serialize each variable value that is to be set. As values are added to the serialized buffer, it will be grown until it reaches a maximum size for the transport, at which point the gre_io_add_mdata() function will return -1 indicating it is full. The data can be then sent by using the gre_io_send_mdata() function which will send the change request to the Storyboard IO plugin and set the appropriate values in the Storyboard application.

gre_io_t                    *send_handle;
gre_io_serialized_data_t    *md_buffer = NULL;
uint32_t                    x;
char                        *ptr;
int                         ret;

/*
 * Connect to the application channel
 */
send_handle = gre_io_open("my_channel", GRE_IO_TYPE_WRONLY);
if(send_handle == NULL) {
  printf("Can't open send handle [%s]\n", argv[1]);
    return 0;
}

/*
 * Add some values to be set in the data manager
 */
ptr = "my string";
ret = gre_io_add_mdata(&md_buffer,
  "Test.String",
  "1s0",
  ptr, strlen(ptr)+1);

x = 1;
ret = gre_io_add_mdata(&md_buffer,
  "Test.Number",
  "4u1",
  &x, sizeof(uint32_t));

/*
 * Send the data to be set in the application.
 */
gre_io_send_mdata(send_handle, md_buffer);