Implementing a Bacula GUI Interface

General

This document is intended mostly for developers who wish to develop a new GUI interface to Bacula.

Minimal Code in Console Program

Until now, I have kept all the Catalog code in the Directory (with the exception of dbcheck and bscan). This is because at some point I would like to add user level security and access. If we have code spread everywhere such as in a GUI this will be more difficult. The other advantage is that any code you add to the Director is automatically available to both the tty console program and the GNOME program. The major disadvantage is it increases the size of the code -- however, compared to Networker the Bacula Director is really tiny.

GUI Interface is Difficult

Interfacing to an interactive program such as Bacula can be very difficult because the interfacing program must interpret all the prompts that may come. This can be next to impossible. There are are a number of ways that Bacula is designed to facilitate this:

• The Bacula network protocol is packet based, and thus pieces of information sent can be ASCII or binary.
• The packet interface permits knowing where the end of a list is.
• The packet interface permits special ``signals'' to be passed rather than data.
• The Director has a number of commands that are non-interactive. They all begin with a period, and provide things such as the list of all Jobs, list of all Clients, list of all Pools, list of all Storage, ... Thus the GUI interface can get to virtually all information that the Director has in a deterministic way. See <bacula-source>/src/dird/ua_dotcmds.c for more details on this.
• Most console commands allow all the arguments to be specified on the command line: e.g. run job=NightlyBackup level=Full

One of the first things to overcome is to be able to establish a conversation with the Director. Although you can write all your own code, it is probably easier to use the Bacula subroutines. The following code is used by the Console program to begin a conversation.

static BSOCK *UA_sock = NULL;
static JCR *jcr;
...
  read-your-config-getting-address-and-pasword;
  UA_sock = bnet_connect(NULL, 5, 15, "Director daemon", dir->address,
                          NULL, dir->DIRport, 0);
   if (UA_sock == NULL) {
      terminate_console(0);
      return 1;
   }
   jcr.dir_bsock = UA_sock;
   if (!authenticate_director(\&jcr, dir)) {
      fprintf(stderr, "ERR=%s", UA_sock->msg);
      terminate_console(0);
      return 1;
   }
   read_and_process_input(stdin, UA_sock);
   if (UA_sock) {
      bnet_sig(UA_sock, BNET_TERMINATE); /* send EOF */
      bnet_close(UA_sock);
   }
   exit 0;

Then the read_and_process_input routine looks like the following:

   get-input-to-send-to-the-Director;
   bnet_fsend(UA_sock, "%s", input);
   stat = bnet_recv(UA_sock);
   process-output-from-the-Director;

For a GUI program things will be a bit more complicated. Basically in the very inner loop, you will need to check and see if any output is available on the UA_sock. For an example, please take a look at the GNOME GUI interface code in: <bacula-source&gt/src/gnome-console/console.c