Moved the calendar backend here. This is the actual calendar-handling

2000-01-18  Federico Mena Quintero  <federico@helixcode.com>

	* cal-backend.c cal-backend.h: Moved the calendar backend here.
	This is the actual calendar-handling object.
	(load_from_vobject): Moved over from calendar.c.  Modified to use
	a CalBackend instead of the old Calendar structure.
	(add_object): Likewise.

	* cal.c: Now the Cal object is just a calendar client interface
	object; we use it as a "viewport" onto a CalBackend.  This also
	lets us do correct resource management.

	* cal-common.h: New file with common forward declarations; we
	can't have circular dependencies between headers.

2000-01-18  Federico Mena Quintero  <federico@helixcode.com>

	* cal-factory.c (cal_factory_load): Queue a load job.
	(load_fn): Load job handler.  Lookup the calendar by URI, load it
	if it is not loaded, or just report it to the new listener if it is.

	* job.c job.h: New files with a simple job queue manager.

	* gnome-calendar.idl (Listener::cal_loaded): Do not return the
	whole calendar object string.  The client will be able to query
	the calendar for the events it needs.

	* cal-listener.c (Listener_cal_loaded): Ref the calendar GNOME
	object.  We unref it when the listener is destroyed.

2000-01-17  Federico Mena Quintero  <federico@helixcode.com>

	The files from the gncal directory of the gnome-pim module on CVS
	were moved here, to evolution/calendar, in preparation for the
	Evolution work.  The calendar is being split into a model/view
	architecture.  The model is a personal calendar server (PAS):  it
	provides storage, notification, and event generation; the
	views/controllers are the calendar user agents and things like
	Pilot synchronizers.

svn path=/trunk/; revision=1591

15 files changed, 1147 insertions, 222 deletions

diff --git a/calendar/ChangeLog b/calendar/ChangeLog
index a934f5145e..3b32e80de3 100644
--- a/calendar/ChangeLog
+++ b/calendar/ChangeLog
@@ -1,5 +1,20 @@
 2000-01-18  Federico Mena Quintero  <federico@helixcode.com>
 
+	* cal-backend.c cal-backend.h: Moved the calendar backend here.
+	This is the actual calendar-handling object.
+	(load_from_vobject): Moved over from calendar.c.  Modified to use
+	a CalBackend instead of the old Calendar structure.
+	(add_object): Likewise.
+
+	* cal.c: Now the Cal object is just a calendar client interface
+	object; we use it as a "viewport" onto a CalBackend.  This also
+	lets us do correct resource management.
+
+	* cal-common.h: New file with common forward declarations; we
+	can't have circular dependencies between headers.
+
+2000-01-18  Federico Mena Quintero  <federico@helixcode.com>
+
 	* cal-factory.c (cal_factory_load): Queue a load job.
 	(load_fn): Load job handler.  Lookup the calendar by URI, load it
 	if it is not loaded, or just report it to the new listener if it is.
@@ -13,6 +28,16 @@
 	* cal-listener.c (Listener_cal_loaded): Ref the calendar GNOME
 	object.  We unref it when the listener is destroyed.
 
+2000-01-17  Federico Mena Quintero  <federico@helixcode.com>
+
+	The files from the gncal directory of the gnome-pim module on CVS
+	were moved here, to evolution/calendar, in preparation for the
+	Evolution work.  The calendar is being split into a model/view
+	architecture.  The model is a personal calendar server (PAS):  it
+	provides storage, notification, and event generation; the
+	views/controllers are the calendar user agents and things like
+	Pilot synchronizers.
+
 2000-01-11  Federico Mena Quintero  <federico@helixcode.com>
 
 	* cal.c: Removed the CORBA listener methods, adjusted for the new
diff --git a/calendar/cal-backend.c b/calendar/cal-backend.c
new file mode 100644
index 0000000000..2fb523dc14
--- /dev/null
+++ b/calendar/cal-backend.c
@@ -0,0 +1,344 @@
+/* GNOME calendar backend
+ *
+ * Copyright (C) 2000 Helix Code, Inc.
+ *
+ * Author: Federico Mena-Quintero <federico@helixcode.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#include <config.h>
+#include "cal-backend.h"
+#include "../libversit/vcc.h"
+
+
+
+/* Private part of the CalBackend structure */
+typedef struct {
+	/* URI where the calendar data is stored */
+	GnomeVFSURI *uri;
+
+	/* List of Cal client interface objects, each with its listener */
+	GList *clients;
+
+	/* All events in the calendar and uri->event hash */
+	GList *events;
+	GHashTable *event_hash;
+
+	/* All TODOs in the calendar */
+	GList *todos;
+
+	/* All journals in the calendar */
+	GList *journals;
+
+	/* Whether a calendar has been loaded */
+	guint loaded : 1;
+} CalBackendPrivate;
+
+
+
+static void cal_backend_class_init (CalBackendClass *class);
+static void cal_backend_init (CalBackend *backend);
+static void cal_backend_destroy (GtkObject *object);
+
+static GtkObjectClass *parent_class;
+
+
+
+/**
+ * cal_backend_get_type:
+ * @void:
+ *
+ * Registers the #CalBackend class if necessary, and returns the type ID
+ * associated to it.
+ *
+ * Return value: The type ID of the #CalBackend class.
+ **/
+GtkType
+cal_backend_get_type (void)
+{
+	static GtkType cal_backend_type = 0;
+
+	if (!cal_backend_type) {
+		static const GtkTypeInfo cal_backend_info = {
+			"CalBackend",
+			sizeof (CalBackend),
+			sizeof (CalBackendClass),
+			(GtkClassInitFunc) cal_backend_class_init,
+			(GtkObjectInitFunc) cal_backend_init,
+			NULL, /* reserved_1 */
+			NULL, /* reserved_2 */
+			(GtkClassInitFunc) NULL
+		};
+
+		cal_backend_type = gtk_type_unique (GTK_TYPE_OBJECT, &cal_backend_info);
+	}
+
+	return cal_backend_type;
+}
+
+/* Class initialization function for the calendar backend */
+static void
+cal_backend_class_init (CalBackendClass *class)
+{
+	GtkObjectClass *object_class;
+
+	object_class = (GtkObjectClass *) class;
+
+	parent_class = gtk_type_class (GTK_TYPE_OBJECT);
+
+	object_class->destroy = cal_backend_destroy;
+}
+
+/* Object initialization function for the calendar backend */
+static void
+cal_backend_init (CalBackend *backend)
+{
+	CalBackendPrivate *priv;
+
+	priv = g_new0 (CalBackendPrivate, 1);
+	backend->priv = priv;
+}
+
+/* Destroy handler for the calendar backend */
+static void
+cal_backend_destroy (GtkObject *object)
+{
+	CalBackend *backend;
+	CalBackendPrivate *priv;
+
+	g_return_if_fail (object != NULL);
+	g_return_if_fail (IS_CAL_BACKEND (object));
+
+	backend = CAL_BACKEND (object);
+	priv = backend->priv;
+
+	/* FIXME: free stuff */
+
+	g_free (priv);
+
+	if (GTK_OBJECT_CLASS (parent_class)->destroy)
+		(* GTK_OBJECT_CLASS (parent_class)->destroy) (object);
+}
+
+
+
+/* Adds an object to the calendar backend */
+static void
+add_object (CalBackend *backend, iCalObject *ico)
+{
+	CalBackendPrivate *priv;
+
+	g_assert (ico != NULL);
+	g_assert (ico->uid != NULL);
+
+	priv = backend->priv;
+
+	ico->new = 0;
+	switch (ico->type) {
+	case ICAL_EVENT:
+		g_hash_table_insert (priv->event_hash, ico->uid, ico);
+		priv->events = g_list_prepend (priv->events, ico);
+#if 0
+		/* FIXME: gnomecal old code */
+		ical_object_try_alarms (ico);
+#ifdef DEBUGGING_MAIL_ALARM
+		ico->malarm.trigger = 0;
+		calendar_notify (0, ico);
+#endif
+#endif
+		break;
+
+	case ICAL_TODO:
+		priv->todos = g_list_prepend (priv->todos, ico);
+		break;
+
+	case ICAL_JOURNAL:
+		priv->journals = g_list_prepend (priv->journals, ico);
+		break;
+
+	default:
+		g_assert_not_reached ();
+	}
+
+	/* FIXME: things must come with an UID! */
+
+	if (!ico->uid) {
+		char buffer [80];
+
+		snprintf (buffer, sizeof (buffer), "GnomeCalendar-%ld\n", time (NULL));
+		ico->uid = g_strdup (buffer);
+	}
+#if 0
+	/* FIXME: gnomecal old code */
+	ico->last_mod = time (NULL);
+#endif
+}
+
+/* Load a calendar from a VObject */
+static void
+load_from_vobject (CalBackend *backend, VObject *vobject)
+{
+	CalBackendPrivate *priv;
+	VObjectIterator i;
+
+	priv = backend->priv;
+
+	g_assert (priv->event_hash == NULL);
+	priv->event_hash = g_hash_table_new (g_str_hash, g_str_equal);
+
+	initPropIterator (&i, vobject);
+
+	while (moreIteration (&i)) {
+		VObject *this;
+		iCalObject *ical;
+		const char *object_name;
+
+		this = nextVObject (&i);
+		object_name = vObjectName (this);
+#if 0
+		/* FIXME?  What is this used for? */
+		if (strcmp (object_name, VCDCreatedProp) == 0) {
+			cal->created = time_from_isodate (str_val (this));
+			continue;
+		}
+#endif
+		if (strcmp (object_name, VCLocationProp) == 0)
+			continue; /* FIXME: imlement */
+
+		if (strcmp (object_name, VCProdIdProp) == 0)
+			continue; /* FIXME: implement */
+
+		if (strcmp (object_name, VCVersionProp) == 0)
+			continue; /* FIXME: implement */
+
+		if (strcmp (object_name, VCTimeZoneProp) == 0)
+			continue; /* FIXME: implement */
+
+		ical = ical_object_create_from_vobject (this, object_name);
+
+		if (ical)
+			add_object (backend, ical);
+	}
+}
+
+
+
+/**
+ * cal_backend_new:
+ * @void:
+ *
+ * Creates a new empty calendar backend.  A calendar must then be loaded or
+ * created before the backend can be used.
+ *
+ * Return value: A newly-created calendar backend.
+ **/
+CalBackend *
+cal_backend_new (void)
+{
+	return CAL_BACKEND (gtk_type_new (TYPE_CAL_BACKEND));
+}
+
+/**
+ * cal_backend_get_uri:
+ * @backend: A calendar backend.
+ *
+ * Queries the URI of a calendar backend, which must already have a loaded
+ * calendar.
+ *
+ * Return value: The URI where the calendar is stored.
+ **/
+GnomeVFSURI *
+cal_backend_get_uri (CalBackend *backend)
+{
+	CalBackendPrivate *priv;
+
+	g_return_val_if_fail (backend != NULL, NULL);
+	g_return_val_if_fail (IS_CAL_BACKEND, NULL);
+
+	priv = backend->priv;
+	g_return_val_if_fail (priv->loaded, NULL);
+	g_assert (priv->uri != NULL);
+
+	return priv->uri;
+}
+
+/**
+ * cal_backend_add_cal:
+ * @backend: A calendar backend.
+ * @cal: A calendar client interface object.
+ *
+ * Adds a calendar client interface object to a calendar @backend.  The calendar
+ * backend must already have a loaded calendar.
+ **/
+void
+cal_backend_add_cal (CalBackend *backend, Cal *cal)
+{
+	CalBackendPrivate *priv;
+
+	g_return_if_fail (backend != NULL);
+	g_return_if_fail (IS_CAL_BACKEND (backend));
+
+	priv = backend->priv;
+	g_return_if_fail (priv->loaded);
+
+	g_return_if_fail (cal != NULL);
+	g_return_if_fail (IS_CAL (cal));
+
+	priv->clients = g_list_prepend (priv->clients, cal);
+}
+
+/**
+ * cal_backend_load:
+ * @backend: A calendar backend.
+ * @str_uri: URI that contains the calendar data.
+ *
+ * Loads a calendar backend with data from a calendar stored at the specified
+ * URI.
+ *
+ * Return value: An operation result code.
+ **/
+CalBackendLoadResult
+cal_backend_load (CalBackend *backend, char *str_uri)
+{
+	CalBackendPrivate *priv;
+	GnomeVFSURI *uri;
+	VObject *vobject;
+
+	g_return_val_if_fail (backend != NULL, CAL_BACKEND_LOAD_ERROR);
+	g_return_val_if_fail (IS_CAL_BACKEND (backend), CAL_BACKEND_LOAD_ERROR);
+	g_return_val_if_fail (str_uri != NULL, CAL_BACKEND_LOAD_ERROR);
+
+	priv = backend->priv;
+	g_return_val_if_fail (!priv->loaded, CAL_BACKEND_LOAD_ERROR);
+
+	uri = gnome_vfs_uri_new (str_uri);
+	if (!uri)
+		return CAL_BACKEND_LOAD_ERROR;
+
+	vobject = Parse_MIME_FromURI (uri);
+	if (!vobject) {
+		gnome_vfs_uri_unref (uri);
+		return CAL_BACKEND_LOAD_ERROR;
+	}
+
+	load_from_vobject (backend, vobject);
+	cleanVObject (vobject);
+	cleanStrTbl ();
+
+	priv->uri = uri;
+	priv->loaded = TRUE;
+	return CAL_BACKEND_LOAD_SUCCESS;
+}
diff --git a/calendar/cal-backend.h b/calendar/cal-backend.h
new file mode 100644
index 0000000000..14cc903ae6
--- /dev/null
+++ b/calendar/cal-backend.h
@@ -0,0 +1,71 @@
+/* GNOME calendar backend
+ *
+ * Copyright (C) 2000 Helix Code, Inc.
+ *
+ * Author: Federico Mena-Quintero <federico@helixcode.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#ifndef CAL_BACKEND_H
+#define CAL_BACKEND_H
+
+#include <libgnome/gnome-defs.h>
+#include "gnome-calendar.h"
+#include "cal-common.h"
+#include "cal.h"
+
+BEGIN_GNOME_DECLS
+
+
+
+#define CAL_BACKEND_TYPE            (cal_backend_get_type ())
+#define CAL_BACKEND(obj)            (GTK_CHECK_CAST ((obj), CAL_BACKEND_TYPE, CalBackend))
+#define CAL_BACKEND_CLASS(klass)    (GTK_CHECK_CLASS_CAST ((klass), CAL_BACKEND_TYPE,		\
+				     CalBackendClass))
+#define IS_CAL_BACKEND(obj)         (GTK_CHECK_TYPE ((obj), CAL_BACKEND_TYPE))
+#define IS_CAL_BACKEND_CLASS(klass) (GTK_CHECK_CLASS_TYPE ((klass), CAL_BACKEND_TYPE))
+
+typedef enum {
+	CAL_BACKEND_LOAD_SUCCESS,		/* Loading OK */
+	CAL_BACKEND_LOAD_ERROR			/* We need better error reporting in libversit */
+} CalBackendLoadResult;
+
+struct _CalBackend {
+	GtkObject object;
+
+	/* Private data */
+	gpointer priv;
+};
+
+struct _CalBackendClass {
+	GtkObjectClass parent_class;
+};
+
+GtkType cal_backend_get_type (void);
+
+CalBackend *cal_backend_new (void);
+
+GnomeVFSURI *cal_backend_get_uri (CalBackend *backend);
+
+void cal_backend_add_cal (CalBackend *backend, Cal *cal);
+
+CalBackendLoadResult cal_backend_load (CalBackend *backend, char *str_uri);
+
+
+
+END_GNOME_DECLS
+
+#endif
diff --git a/calendar/cal-common.h b/calendar/cal-common.h
new file mode 100644
index 0000000000..4177dbb096
--- /dev/null
+++ b/calendar/cal-common.h
@@ -0,0 +1,41 @@
+/* GNOME calendar server - common declarations
+ *
+ * Copyright (C) 2000 Helix Code, Inc.
+ *
+ * Author: Federico Mena-Quintero <federico@helixcode.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#ifndef CAL_COMMON_H
+#define CAL_COMMON_H
+
+#include <libgnome/gnome-defs.h>
+
+BEGIN_GNOME_DECLS
+
+
+
+typedef struct _CalBackend CalBackend;
+typedef struct _CalBackendClass CalBackendClass;
+
+typedef struct _Cal Cal;
+typedef struct _CalClass CalClass;
+
+
+
+END_GNOME_DECLS
+
+#endif
diff --git a/calendar/cal-factory.c b/calendar/cal-factory.c
index ac1043bc10..053baebe5c 100644
--- a/calendar/cal-factory.c
+++ b/calendar/cal-factory.c
@@ -187,20 +187,6 @@ cal_factory_get_epv (void)
 	return epv;
 }
 
-/* Returns whether a CORBA object is nil */
-static gboolean
-corba_object_is_nil (CORBA_Object object)
-{
-	CORBA_Environment ev;
-	gboolean retval;
-
-	CORBA_exception_init (&ev);
-	retval = CORBA_Object_is_nil (object, &ev);
-	CORBA_exception_free (&ev);
-
-	return retval;
-}
-
 
 
 /* Loading and creating calendars */
@@ -288,7 +274,6 @@ cal_factory_construct (CalFactory *factory, GNOME_Calendar_CalFactory corba_fact
 {
 	g_return_val_if_fail (factory != NULL, NULL);
 	g_return_val_if_fail (IS_CAL_FACTORY (factory), NULL);
-	g_return_val_if_fail (!corba_object_is_nil (corba_factory), NULL);
 
 	gnome_object_construct (GNOME_OBJECT (factory), corba_factory);
 	return factory;
@@ -319,6 +304,7 @@ cal_factory_corba_object_create (GnomeObject *object)
 	CORBA_exception_init (&ev);
 	POA_GNOME_Calendar_CalFactory__init ((PortableServer_Servant) servant, &ev);
 	if (ev._major != CORBA_NO_EXCEPTION) {
+		g_message ("cal_factory_corba_object_create(): could not init the servant");
 		g_free (servant);
 		CORBA_exception_free (&ev);
 		return CORBA_OBJECT_NIL;
@@ -341,15 +327,25 @@ CalFactory *
 cal_factory_new (void)
 {
 	CalFactory *factory;
+	CORBA_Environment ev;
 	GNOME_Calendar_CalFactory corba_factory;
+	gboolean retval;
 
 	factory = gtk_type_new (CAL_FACTORY_TYPE);
+
 	corba_factory = cal_factory_corba_object_create (GNOME_OBJECT (factory));
-	if (corba_object_is_nil (corba_factory)) {
-		gtk_object_destroy (factory);
+	CORBA_exception_init (&ev);
+	retval = CORBA_Object_is_nil (corba_factory, &ev);
+
+	if (ev._major != CORBA_NO_EXCEPTION || retval) {
+		g_message ("cal_factory_new(): could not create the CORBA object");
+		gtk_object_unref (factory);
+		CORBA_exception_free (&ev);
 		return NULL;
 	}
 
+	CORBA_exception_free (&ev);
+
 	return cal_factory_construct (factory, corba_factory);
 }
 
@@ -358,18 +354,25 @@ cal_factory_load (CalFactory *factory, const char *uri, GNOME_Calendar_Listener
 {
 	LoadCreateJobData *jd;
 	CORBA_Environment ev;
+	GNOME_Calendar_Listener listener_copy;
 
 	CORBA_exception_init (&ev);
 
+	listener_copy = CORBA_Object_duplicate (listener, &ev);
+	if (ev._major != CORBA_NO_EXCEPTION) {
+		g_message ("cal_factory_load(): could not duplicate the listener");
+		CORBA_exception_free (&ev);
+		return;
+	}
+
+	CORBA_exception_free (&ev);
+
 	jd = g_new (LoadCreateJobData, 1);
 	jd->factory = factory;
 	jd->uri = g_strdup (uri);
-	jd->listener = CORBA_Object_duplicate (listener, &ev);
-	GNOME_Unknown_ref (jd->listener);
+	jd->listener = listener_copy;
 
 	job_add (load_fn, jd);
-
-	CORBA_exception_free (&ev);
 }
 
 void
diff --git a/calendar/cal.c b/calendar/cal.c
index 3394ead5d8..26c0581ff7 100644
--- a/calendar/cal.c
+++ b/calendar/cal.c
@@ -1,4 +1,4 @@
-/* GNOME calendar object
+/* GNOME calendar client interface object
  *
  * Copyright (C) 2000 Helix Code, Inc.
  *
@@ -21,16 +21,17 @@
 
 #include <config.h>
 #include "cal.h"
+#include "cal-backend.h"
 
 
 
 /* Private part of the Cal structure */
 typedef struct {
-	/* The URI where this calendar is stored */
-	char *uri;
+	/* Our backend */
+	CalBackend *backend;
 
-	/* List of listeners for this calendar */
-	GList *listeners;
+	/* Listener on the client we notify */
+	GNOME_Calendar_listener listener;
 } CalPrivate;
 
 
@@ -71,7 +72,7 @@ cal_get_type (void)
 			(GtkClassInitFunc) NULL
 		};
 
-		cal_type = gtk_type_unique (gnome_object_get_type (), &cal_info);
+		cal_type = gtk_type_unique (GNOME_OBJECT_TYPE, &cal_info);
 	}
 
 	return cal_type;
@@ -93,7 +94,7 @@ cal_class_init (CalClass *class)
 
 	object_class = (GtkObjectClass *) class;
 
-	parent_class = gtk_type_class (gnome_object_get_type ());
+	parent_class = gtk_type_class (GNOME_OBJECT_TYPE);
 
 	object_class->destroy = cal_destroy;
 
@@ -108,6 +109,8 @@ cal_init (Cal *cal)
 
 	priv = g_new0 (CalPrivate, 1);
 	cal->priv = priv;
+
+	priv->listener = CORBA_OBJECT_NIL;
 }
 
 /* Destroy handler for the calendar */
@@ -183,35 +186,47 @@ cal_get_epv (void)
 
 
 
-/* Returns whether a CORBA object is nil */
-static gboolean
-corba_object_is_nil (CORBA_Object object)
-{
-	CORBA_Environment ev;
-	gboolean retval;
-
-	CORBA_exception_init (&ev);
-	retval = CORBA_Object_is_nil (object, &ev);
-	CORBA_exception_free (&ev);
-
-	return retval;
-}
-
 /**
  * cal_construct:
- * @cal: A calendar.
+ * @cal: A calendar client interface.
  * @corba_cal: CORBA object for the calendar.
+ * @backend: Calendar backend that this @cal presents an interface to.
+ * @listener: Calendar listener for notification.
  *
- * Constructs a calendar by binding the corresponding CORBA object to it.
+ * Constructs a calendar client interface object by binding the corresponding
+ * CORBA object to it.  The calendar interface is bound to the specified
+ * @backend, and will notify the @listener about changes to the calendar.
  *
  * Return value: The same object as the @cal argument.
  **/
 Cal *
-cal_construct (Cal *cal, GNOME_Calendar_Cal corba_cal)
+cal_construct (Cal *cal,
+	       GNOME_Calendar_Cal corba_cal,
+	       CalBackend *backend,
+	       GNOME_Calendar_Listener listener)
 {
+	CalPrivate *priv;
+	CORBA_Environment ev;
+
 	g_return_val_if_fail (cal != NULL, NULL);
 	g_return_val_if_fail (IS_CAL (cal), NULL);
-	g_return_val_if_fail (!corba_object_is_nil (corba_cal), NULL);
+	g_return_val_if_fail (backend != NULL);
+	g_return_val_if_fail (IS_CAL_BACKEND (backend));
+
+	priv = cal->priv;
+
+	CORBA_exception_init (&ev);
+	priv->listener = CORBA_Object_duplicate (listener, &ev);
+	if (ev._major != CORBA_NO_EXCEPTION) {
+		g_message ("cal_construct: could not duplicate the listener");
+		priv->listener = CORBA_OBJECT_NIL;
+		CORBA_exception_free (&ev);
+		return NULL;
+	}
+
+	CORBA_exception_free (&ev);
+
+	priv->backend = backend;
 
 	gnome_object_construct (GNOME_OBJECT (cal), corba_cal);
 	return cal;
@@ -222,7 +237,7 @@ cal_construct (Cal *cal, GNOME_Calendar_Cal corba_cal)
  * @object: #GnomeObject that will wrap the CORBA object.
  *
  * Creates and activates the CORBA object that is wrapped by the specified
- * calendar @object.
+ * calendar client interface @object.
  *
  * Return value: An activated object reference or #CORBA_OBJECT_NIL in case of
  * failure.
@@ -242,6 +257,7 @@ cal_corba_object_create (GnomeObject *object)
 	CORBA_exception_init (&ev);
 	POA_GNOME_Calendar_Cal__init ((PortableServer_Servant) servant, &ev);
 	if (ev._major != CORBA_NO_EXCEPTION) {
+		g_message ("cal_corba_object_create(): could not init the servant");
 		g_free (servant);
 		CORBA_exception_free (&ev);
 		return CORBA_OBJECT_NIL;
@@ -252,69 +268,47 @@ cal_corba_object_create (GnomeObject *object)
 }
 
 /**
- * cal_add_listener:
- * @cal: A calendar.
- * @listener: A listener.
+ * cal_new:
+ * @backend: A calendar backend.
+ * @listener: A calendar listener.
+ *
+ * Creates a new calendar client interface object and binds it to the specified
+ * @backend and @listener objects.
  *
- * Adds a listener for changes to a calendar.  The specified listener object
- * will be used for notification when objects are added, removed, or changed in
- * the calendar.
+ * Return value: A newly-created #Cal calendar client interface object, or NULL
+ * if its corresponding CORBA object could not be created.
  **/
-void
-cal_add_listener (Cal *cal, GNOME_Calendar_Listener listener)
+Cal *
+cal_new (CalBackend *backend, GNOME_Calendar_Listener listener)
 {
-	CalPrivate *priv;
+	Cal *cal, *retval;
+	GNOME_Calendar_Cal corba_cal;
 	CORBA_Environment ev;
+	gboolean ret;
 
-	g_return_if_fail (cal != NULL);
-	g_return_if_fail (IS_CAL (cal));
-	g_return_if_fail (!corba_object_is_nil (listener));
+	g_return_val_if_fail (backend != NULL);
+	g_return_val_if_fail (IS_CAL_BACKEND (backend));
 
-	priv = cal->priv;
+	cal = CAL (gtk_type_new (CAL_TYPE));
+	corba_cal = cal_corba_object_create (GNOME_OBJECT (cal));
 
 	CORBA_exception_init (&ev);
-
-	GNOME_Unknown_ref (listener, &ev);
-	priv->listeners = g_list_prepend (priv->listeners, CORBA_Object_duplicate (listener, &ev));
+	ret = CORBA_object_is_nil (corba_cal, &ev);
+	if (ev._major != CORBA_NO_EXCEPTION || ret) {
+		g_message ("cal_new(): could not create the CORBA object");
+		gtk_object_unref (GTK_OBJECT (cal));
+		CORBA_exception_free (&ev);
+		return NULL;
+	}
 
 	CORBA_exception_free (&ev);
-}
 
-/**
- * cal_remove_listener:
- * @cal: A calendar.
- * @listener: A listener.
- *
- * Removes a listener from a calendar so that no more notification events will
- * be sent to the listener.
- **/
-void
-cal_remove_listener (Cal *cal, GNOME_Calendar_Listener listener)
-{
-	CalPrivate *priv;
-	CORBA_Environment ev;
-	GList *l;
-
-	g_return_if_fail (cal != NULL);
-	g_return_if_fail (IS_CAL (cal));
-
-	priv = cal->priv;
-
-	CORBA_exception_init (&ev);
-
-	/* FIXME: CORBA_Object_is_equivalent() is not what one thinks.  This
-	 * code could fail in situtations subtle enough that I don't understand
-	 * them.  Someone has to figure out the standard CORBA idiom for
-	 * listeners or notification.
-	 */
-	for (l = priv->listeners; l; l = l->next)
-		if (CORBA_Object_is_equivalent (listener, l->data)) {
-			GNOME_Unknown_unref (listener, &ev);
-			CORBA_Object_release (listener, &ev);
-			priv->listeners = g_list_remove_link (priv->listeners, l);
-			g_list_free_1 (l);
-			break;
-		}
+	retval = cal_construct (cal, corba_cal, backend, listener);
+	if (!retval) {
+		g_message ("cal_new(): could not construct the calendar client interface");
+		gtk_object_unref (cal);
+		return NULL;
+	}
 
-	CORBA_exception_free (&ev);
+	return retval;
 }
diff --git a/calendar/cal.h b/calendar/cal.h
index 959331595c..80d349d44d 100644
--- a/calendar/cal.h
+++ b/calendar/cal.h
@@ -1,4 +1,4 @@
-/* GNOME calendar object
+/* GNOME calendar client interface object
  *
  * Copyright (C) 2000 Helix Code, Inc.
  *
@@ -25,6 +25,7 @@
 #include <libgnome/gnome-defs.h>
 #include <bonobo/gnome-object.h>
 #include "gnome-calendar.h"
+#include "cal-common.h"
 
 BEGIN_GNOME_DECLS
 
@@ -36,9 +37,6 @@ BEGIN_GNOME_DECLS
 #define IS_CAL(obj)         (GTK_CHECK_TYPE ((obj), CAL_TYPE))
 #define IS_CAL_CLASS(klass) (GTK_CHECK_CLASS_TYPE ((klass), CAL_TYPE))
 
-typedef struct _Cal Cal;
-typedef struct _CalClass CalClass;
-
 struct _Cal {
 	GnomeObject object;
 
@@ -52,14 +50,13 @@ struct _CalClass {
 
 GtkType cal_get_type (void);
 
-Cal *cal_construct (Cal *cal, GNOME_Calendar_Cal corba_cal);
+Cal *cal_construct (Cal *cal,
+		    GNOME_Calendar_Cal corba_cal,
+		    CalBackend *backend,
+		    GNOME_Calendar_Listener listener);
 GNOME_Calendar_Cal cal_corba_object_create (GnomeObject *object);
 
-Cal *cal_new (char *uri);
-Cal *cal_new_from_file (char *uri);
-
-void cal_add_listener (Cal *cal, GNOME_Calendar_Listener listener);
-void cal_remove_listener (Cal *cal, GNOME_Calendar_Listener listener);
+Cal *cal_new (CalBackend *backend, GNOME_Calendar_Listener listener);
 
 POA_GNOME_Calendar_Cal__epv *cal_get_epv (void);
 
diff --git a/calendar/evolution-calendar.idl b/calendar/evolution-calendar.idl
index 77d4c1193c..9ff87f62f6 100644
--- a/calendar/evolution-calendar.idl
+++ b/calendar/evolution-calendar.idl
@@ -25,7 +25,7 @@ module Calendar {
 
 	interface Listener;
 
-	/* A calendar handle */
+	/* Calendar client interface */
 	interface Cal : Unknown {
 		/* A calendar is identified by its URI */
 		readonly attribute string uri;
diff --git a/calendar/idl/evolution-calendar.idl b/calendar/idl/evolution-calendar.idl
index 77d4c1193c..9ff87f62f6 100644
--- a/calendar/idl/evolution-calendar.idl
+++ b/calendar/idl/evolution-calendar.idl
@@ -25,7 +25,7 @@ module Calendar {
 
 	interface Listener;
 
-	/* A calendar handle */
+	/* Calendar client interface */
 	interface Cal : Unknown {
 		/* A calendar is identified by its URI */
 		readonly attribute string uri;
diff --git a/calendar/pcs/cal-backend.c b/calendar/pcs/cal-backend.c
new file mode 100644
index 0000000000..2fb523dc14
--- /dev/null
+++ b/calendar/pcs/cal-backend.c
@@ -0,0 +1,344 @@
+/* GNOME calendar backend
+ *
+ * Copyright (C) 2000 Helix Code, Inc.
+ *
+ * Author: Federico Mena-Quintero <federico@helixcode.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#include <config.h>
+#include "cal-backend.h"
+#include "../libversit/vcc.h"
+
+
+
+/* Private part of the CalBackend structure */
+typedef struct {
+	/* URI where the calendar data is stored */
+	GnomeVFSURI *uri;
+
+	/* List of Cal client interface objects, each with its listener */
+	GList *clients;
+
+	/* All events in the calendar and uri->event hash */
+	GList *events;
+	GHashTable *event_hash;
+
+	/* All TODOs in the calendar */
+	GList *todos;
+
+	/* All journals in the calendar */
+	GList *journals;
+
+	/* Whether a calendar has been loaded */
+	guint loaded : 1;
+} CalBackendPrivate;
+
+
+
+static void cal_backend_class_init (CalBackendClass *class);
+static void cal_backend_init (CalBackend *backend);
+static void cal_backend_destroy (GtkObject *object);
+
+static GtkObjectClass *parent_class;
+
+
+
+/**
+ * cal_backend_get_type:
+ * @void:
+ *
+ * Registers the #CalBackend class if necessary, and returns the type ID
+ * associated to it.
+ *
+ * Return value: The type ID of the #CalBackend class.
+ **/
+GtkType
+cal_backend_get_type (void)
+{
+	static GtkType cal_backend_type = 0;
+
+	if (!cal_backend_type) {
+		static const GtkTypeInfo cal_backend_info = {
+			"CalBackend",
+			sizeof (CalBackend),
+			sizeof (CalBackendClass),
+			(GtkClassInitFunc) cal_backend_class_init,
+			(GtkObjectInitFunc) cal_backend_init,
+			NULL, /* reserved_1 */
+			NULL, /* reserved_2 */
+			(GtkClassInitFunc) NULL
+		};
+
+		cal_backend_type = gtk_type_unique (GTK_TYPE_OBJECT, &cal_backend_info);
+	}
+
+	return cal_backend_type;
+}
+
+/* Class initialization function for the calendar backend */
+static void
+cal_backend_class_init (CalBackendClass *class)
+{
+	GtkObjectClass *object_class;
+
+	object_class = (GtkObjectClass *) class;
+
+	parent_class = gtk_type_class (GTK_TYPE_OBJECT);
+
+	object_class->destroy = cal_backend_destroy;
+}
+
+/* Object initialization function for the calendar backend */
+static void
+cal_backend_init (CalBackend *backend)
+{
+	CalBackendPrivate *priv;
+
+	priv = g_new0 (CalBackendPrivate, 1);
+	backend->priv = priv;
+}
+
+/* Destroy handler for the calendar backend */
+static void
+cal_backend_destroy (GtkObject *object)
+{
+	CalBackend *backend;
+	CalBackendPrivate *priv;
+
+	g_return_if_fail (object != NULL);
+	g_return_if_fail (IS_CAL_BACKEND (object));
+
+	backend = CAL_BACKEND (object);
+	priv = backend->priv;
+
+	/* FIXME: free stuff */
+
+	g_free (priv);
+
+	if (GTK_OBJECT_CLASS (parent_class)->destroy)
+		(* GTK_OBJECT_CLASS (parent_class)->destroy) (object);
+}
+
+
+
+/* Adds an object to the calendar backend */
+static void
+add_object (CalBackend *backend, iCalObject *ico)
+{
+	CalBackendPrivate *priv;
+
+	g_assert (ico != NULL);
+	g_assert (ico->uid != NULL);
+
+	priv = backend->priv;
+
+	ico->new = 0;
+	switch (ico->type) {
+	case ICAL_EVENT:
+		g_hash_table_insert (priv->event_hash, ico->uid, ico);
+		priv->events = g_list_prepend (priv->events, ico);
+#if 0
+		/* FIXME: gnomecal old code */
+		ical_object_try_alarms (ico);
+#ifdef DEBUGGING_MAIL_ALARM
+		ico->malarm.trigger = 0;
+		calendar_notify (0, ico);
+#endif
+#endif
+		break;
+
+	case ICAL_TODO:
+		priv->todos = g_list_prepend (priv->todos, ico);
+		break;
+
+	case ICAL_JOURNAL:
+		priv->journals = g_list_prepend (priv->journals, ico);
+		break;
+
+	default:
+		g_assert_not_reached ();
+	}
+
+	/* FIXME: things must come with an UID! */
+
+	if (!ico->uid) {
+		char buffer [80];
+
+		snprintf (buffer, sizeof (buffer), "GnomeCalendar-%ld\n", time (NULL));
+		ico->uid = g_strdup (buffer);
+	}
+#if 0
+	/* FIXME: gnomecal old code */
+	ico->last_mod = time (NULL);
+#endif
+}
+
+/* Load a calendar from a VObject */
+static void
+load_from_vobject (CalBackend *backend, VObject *vobject)
+{
+	CalBackendPrivate *priv;
+	VObjectIterator i;
+
+	priv = backend->priv;
+
+	g_assert (priv->event_hash == NULL);
+	priv->event_hash = g_hash_table_new (g_str_hash, g_str_equal);
+
+	initPropIterator (&i, vobject);
+
+	while (moreIteration (&i)) {
+		VObject *this;
+		iCalObject *ical;
+		const char *object_name;
+
+		this = nextVObject (&i);
+		object_name = vObjectName (this);
+#if 0
+		/* FIXME?  What is this used for? */
+		if (strcmp (object_name, VCDCreatedProp) == 0) {
+			cal->created = time_from_isodate (str_val (this));
+			continue;
+		}
+#endif
+		if (strcmp (object_name, VCLocationProp) == 0)
+			continue; /* FIXME: imlement */
+
+		if (strcmp (object_name, VCProdIdProp) == 0)
+			continue; /* FIXME: implement */
+
+		if (strcmp (object_name, VCVersionProp) == 0)
+			continue; /* FIXME: implement */
+
+		if (strcmp (object_name, VCTimeZoneProp) == 0)
+			continue; /* FIXME: implement */
+
+		ical = ical_object_create_from_vobject (this, object_name);
+
+		if (ical)
+			add_object (backend, ical);
+	}
+}
+
+
+
+/**
+ * cal_backend_new:
+ * @void:
+ *
+ * Creates a new empty calendar backend.  A calendar must then be loaded or
+ * created before the backend can be used.
+ *
+ * Return value: A newly-created calendar backend.
+ **/
+CalBackend *
+cal_backend_new (void)
+{
+	return CAL_BACKEND (gtk_type_new (TYPE_CAL_BACKEND));
+}
+
+/**
+ * cal_backend_get_uri:
+ * @backend: A calendar backend.
+ *
+ * Queries the URI of a calendar backend, which must already have a loaded
+ * calendar.
+ *
+ * Return value: The URI where the calendar is stored.
+ **/
+GnomeVFSURI *
+cal_backend_get_uri (CalBackend *backend)
+{
+	CalBackendPrivate *priv;
+
+	g_return_val_if_fail (backend != NULL, NULL);
+	g_return_val_if_fail (IS_CAL_BACKEND, NULL);
+
+	priv = backend->priv;
+	g_return_val_if_fail (priv->loaded, NULL);
+	g_assert (priv->uri != NULL);
+
+	return priv->uri;
+}
+
+/**
+ * cal_backend_add_cal:
+ * @backend: A calendar backend.
+ * @cal: A calendar client interface object.
+ *
+ * Adds a calendar client interface object to a calendar @backend.  The calendar
+ * backend must already have a loaded calendar.
+ **/
+void
+cal_backend_add_cal (CalBackend *backend, Cal *cal)
+{
+	CalBackendPrivate *priv;
+
+	g_return_if_fail (backend != NULL);
+	g_return_if_fail (IS_CAL_BACKEND (backend));
+
+	priv = backend->priv;
+	g_return_if_fail (priv->loaded);
+
+	g_return_if_fail (cal != NULL);
+	g_return_if_fail (IS_CAL (cal));
+
+	priv->clients = g_list_prepend (priv->clients, cal);
+}
+
+/**
+ * cal_backend_load:
+ * @backend: A calendar backend.
+ * @str_uri: URI that contains the calendar data.
+ *
+ * Loads a calendar backend with data from a calendar stored at the specified
+ * URI.
+ *
+ * Return value: An operation result code.
+ **/
+CalBackendLoadResult
+cal_backend_load (CalBackend *backend, char *str_uri)
+{
+	CalBackendPrivate *priv;
+	GnomeVFSURI *uri;
+	VObject *vobject;
+
+	g_return_val_if_fail (backend != NULL, CAL_BACKEND_LOAD_ERROR);
+	g_return_val_if_fail (IS_CAL_BACKEND (backend), CAL_BACKEND_LOAD_ERROR);
+	g_return_val_if_fail (str_uri != NULL, CAL_BACKEND_LOAD_ERROR);
+
+	priv = backend->priv;
+	g_return_val_if_fail (!priv->loaded, CAL_BACKEND_LOAD_ERROR);
+
+	uri = gnome_vfs_uri_new (str_uri);
+	if (!uri)
+		return CAL_BACKEND_LOAD_ERROR;
+
+	vobject = Parse_MIME_FromURI (uri);
+	if (!vobject) {
+		gnome_vfs_uri_unref (uri);
+		return CAL_BACKEND_LOAD_ERROR;
+	}
+
+	load_from_vobject (backend, vobject);
+	cleanVObject (vobject);
+	cleanStrTbl ();
+
+	priv->uri = uri;
+	priv->loaded = TRUE;
+	return CAL_BACKEND_LOAD_SUCCESS;
+}
diff --git a/calendar/pcs/cal-backend.h b/calendar/pcs/cal-backend.h
new file mode 100644
index 0000000000..14cc903ae6
--- /dev/null
+++ b/calendar/pcs/cal-backend.h
@@ -0,0 +1,71 @@
+/* GNOME calendar backend
+ *
+ * Copyright (C) 2000 Helix Code, Inc.
+ *
+ * Author: Federico Mena-Quintero <federico@helixcode.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#ifndef CAL_BACKEND_H
+#define CAL_BACKEND_H
+
+#include <libgnome/gnome-defs.h>
+#include "gnome-calendar.h"
+#include "cal-common.h"
+#include "cal.h"
+
+BEGIN_GNOME_DECLS
+
+
+
+#define CAL_BACKEND_TYPE            (cal_backend_get_type ())
+#define CAL_BACKEND(obj)            (GTK_CHECK_CAST ((obj), CAL_BACKEND_TYPE, CalBackend))
+#define CAL_BACKEND_CLASS(klass)    (GTK_CHECK_CLASS_CAST ((klass), CAL_BACKEND_TYPE,		\
+				     CalBackendClass))
+#define IS_CAL_BACKEND(obj)         (GTK_CHECK_TYPE ((obj), CAL_BACKEND_TYPE))
+#define IS_CAL_BACKEND_CLASS(klass) (GTK_CHECK_CLASS_TYPE ((klass), CAL_BACKEND_TYPE))
+
+typedef enum {
+	CAL_BACKEND_LOAD_SUCCESS,		/* Loading OK */
+	CAL_BACKEND_LOAD_ERROR			/* We need better error reporting in libversit */
+} CalBackendLoadResult;
+
+struct _CalBackend {
+	GtkObject object;
+
+	/* Private data */
+	gpointer priv;
+};
+
+struct _CalBackendClass {
+	GtkObjectClass parent_class;
+};
+
+GtkType cal_backend_get_type (void);
+
+CalBackend *cal_backend_new (void);
+
+GnomeVFSURI *cal_backend_get_uri (CalBackend *backend);
+
+void cal_backend_add_cal (CalBackend *backend, Cal *cal);
+
+CalBackendLoadResult cal_backend_load (CalBackend *backend, char *str_uri);
+
+
+
+END_GNOME_DECLS
+
+#endif
diff --git a/calendar/pcs/cal-common.h b/calendar/pcs/cal-common.h
new file mode 100644
index 0000000000..4177dbb096
--- /dev/null
+++ b/calendar/pcs/cal-common.h
@@ -0,0 +1,41 @@
+/* GNOME calendar server - common declarations
+ *
+ * Copyright (C) 2000 Helix Code, Inc.
+ *
+ * Author: Federico Mena-Quintero <federico@helixcode.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#ifndef CAL_COMMON_H
+#define CAL_COMMON_H
+
+#include <libgnome/gnome-defs.h>
+
+BEGIN_GNOME_DECLS
+
+
+
+typedef struct _CalBackend CalBackend;
+typedef struct _CalBackendClass CalBackendClass;
+
+typedef struct _Cal Cal;
+typedef struct _CalClass CalClass;
+
+
+
+END_GNOME_DECLS
+
+#endif
diff --git a/calendar/pcs/cal-factory.c b/calendar/pcs/cal-factory.c
index ac1043bc10..053baebe5c 100644
--- a/calendar/pcs/cal-factory.c
+++ b/calendar/pcs/cal-factory.c
@@ -187,20 +187,6 @@ cal_factory_get_epv (void)
 	return epv;
 }
 
-/* Returns whether a CORBA object is nil */
-static gboolean
-corba_object_is_nil (CORBA_Object object)
-{
-	CORBA_Environment ev;
-	gboolean retval;
-
-	CORBA_exception_init (&ev);
-	retval = CORBA_Object_is_nil (object, &ev);
-	CORBA_exception_free (&ev);
-
-	return retval;
-}
-
 
 
 /* Loading and creating calendars */
@@ -288,7 +274,6 @@ cal_factory_construct (CalFactory *factory, GNOME_Calendar_CalFactory corba_fact
 {
 	g_return_val_if_fail (factory != NULL, NULL);
 	g_return_val_if_fail (IS_CAL_FACTORY (factory), NULL);
-	g_return_val_if_fail (!corba_object_is_nil (corba_factory), NULL);
 
 	gnome_object_construct (GNOME_OBJECT (factory), corba_factory);
 	return factory;
@@ -319,6 +304,7 @@ cal_factory_corba_object_create (GnomeObject *object)
 	CORBA_exception_init (&ev);
 	POA_GNOME_Calendar_CalFactory__init ((PortableServer_Servant) servant, &ev);
 	if (ev._major != CORBA_NO_EXCEPTION) {
+		g_message ("cal_factory_corba_object_create(): could not init the servant");
 		g_free (servant);
 		CORBA_exception_free (&ev);
 		return CORBA_OBJECT_NIL;
@@ -341,15 +327,25 @@ CalFactory *
 cal_factory_new (void)
 {
 	CalFactory *factory;
+	CORBA_Environment ev;
 	GNOME_Calendar_CalFactory corba_factory;
+	gboolean retval;
 
 	factory = gtk_type_new (CAL_FACTORY_TYPE);
+
 	corba_factory = cal_factory_corba_object_create (GNOME_OBJECT (factory));
-	if (corba_object_is_nil (corba_factory)) {
-		gtk_object_destroy (factory);
+	CORBA_exception_init (&ev);
+	retval = CORBA_Object_is_nil (corba_factory, &ev);
+
+	if (ev._major != CORBA_NO_EXCEPTION || retval) {
+		g_message ("cal_factory_new(): could not create the CORBA object");
+		gtk_object_unref (factory);
+		CORBA_exception_free (&ev);
 		return NULL;
 	}
 
+	CORBA_exception_free (&ev);
+
 	return cal_factory_construct (factory, corba_factory);
 }
 
@@ -358,18 +354,25 @@ cal_factory_load (CalFactory *factory, const char *uri, GNOME_Calendar_Listener
 {
 	LoadCreateJobData *jd;
 	CORBA_Environment ev;
+	GNOME_Calendar_Listener listener_copy;
 
 	CORBA_exception_init (&ev);
 
+	listener_copy = CORBA_Object_duplicate (listener, &ev);
+	if (ev._major != CORBA_NO_EXCEPTION) {
+		g_message ("cal_factory_load(): could not duplicate the listener");
+		CORBA_exception_free (&ev);
+		return;
+	}
+
+	CORBA_exception_free (&ev);
+
 	jd = g_new (LoadCreateJobData, 1);
 	jd->factory = factory;
 	jd->uri = g_strdup (uri);
-	jd->listener = CORBA_Object_duplicate (listener, &ev);
-	GNOME_Unknown_ref (jd->listener);
+	jd->listener = listener_copy;
 
 	job_add (load_fn, jd);
-
-	CORBA_exception_free (&ev);
 }
 
 void
diff --git a/calendar/pcs/cal.c b/calendar/pcs/cal.c
index 3394ead5d8..26c0581ff7 100644
--- a/calendar/pcs/cal.c
+++ b/calendar/pcs/cal.c
@@ -1,4 +1,4 @@
-/* GNOME calendar object
+/* GNOME calendar client interface object
  *
  * Copyright (C) 2000 Helix Code, Inc.
  *
@@ -21,16 +21,17 @@
 
 #include <config.h>
 #include "cal.h"
+#include "cal-backend.h"
 
 
 
 /* Private part of the Cal structure */
 typedef struct {
-	/* The URI where this calendar is stored */
-	char *uri;
+	/* Our backend */
+	CalBackend *backend;
 
-	/* List of listeners for this calendar */
-	GList *listeners;
+	/* Listener on the client we notify */
+	GNOME_Calendar_listener listener;
 } CalPrivate;
 
 
@@ -71,7 +72,7 @@ cal_get_type (void)
 			(GtkClassInitFunc) NULL
 		};
 
-		cal_type = gtk_type_unique (gnome_object_get_type (), &cal_info);
+		cal_type = gtk_type_unique (GNOME_OBJECT_TYPE, &cal_info);
 	}
 
 	return cal_type;
@@ -93,7 +94,7 @@ cal_class_init (CalClass *class)
 
 	object_class = (GtkObjectClass *) class;
 
-	parent_class = gtk_type_class (gnome_object_get_type ());
+	parent_class = gtk_type_class (GNOME_OBJECT_TYPE);
 
 	object_class->destroy = cal_destroy;
 
@@ -108,6 +109,8 @@ cal_init (Cal *cal)
 
 	priv = g_new0 (CalPrivate, 1);
 	cal->priv = priv;
+
+	priv->listener = CORBA_OBJECT_NIL;
 }
 
 /* Destroy handler for the calendar */
@@ -183,35 +186,47 @@ cal_get_epv (void)
 
 
 
-/* Returns whether a CORBA object is nil */
-static gboolean
-corba_object_is_nil (CORBA_Object object)
-{
-	CORBA_Environment ev;
-	gboolean retval;
-
-	CORBA_exception_init (&ev);
-	retval = CORBA_Object_is_nil (object, &ev);
-	CORBA_exception_free (&ev);
-
-	return retval;
-}
-
 /**
  * cal_construct:
- * @cal: A calendar.
+ * @cal: A calendar client interface.
  * @corba_cal: CORBA object for the calendar.
+ * @backend: Calendar backend that this @cal presents an interface to.
+ * @listener: Calendar listener for notification.
  *
- * Constructs a calendar by binding the corresponding CORBA object to it.
+ * Constructs a calendar client interface object by binding the corresponding
+ * CORBA object to it.  The calendar interface is bound to the specified
+ * @backend, and will notify the @listener about changes to the calendar.
  *
  * Return value: The same object as the @cal argument.
  **/
 Cal *
-cal_construct (Cal *cal, GNOME_Calendar_Cal corba_cal)
+cal_construct (Cal *cal,
+	       GNOME_Calendar_Cal corba_cal,
+	       CalBackend *backend,
+	       GNOME_Calendar_Listener listener)
 {
+	CalPrivate *priv;
+	CORBA_Environment ev;
+
 	g_return_val_if_fail (cal != NULL, NULL);
 	g_return_val_if_fail (IS_CAL (cal), NULL);
-	g_return_val_if_fail (!corba_object_is_nil (corba_cal), NULL);
+	g_return_val_if_fail (backend != NULL);
+	g_return_val_if_fail (IS_CAL_BACKEND (backend));
+
+	priv = cal->priv;
+
+	CORBA_exception_init (&ev);
+	priv->listener = CORBA_Object_duplicate (listener, &ev);
+	if (ev._major != CORBA_NO_EXCEPTION) {
+		g_message ("cal_construct: could not duplicate the listener");
+		priv->listener = CORBA_OBJECT_NIL;
+		CORBA_exception_free (&ev);
+		return NULL;
+	}
+
+	CORBA_exception_free (&ev);
+
+	priv->backend = backend;
 
 	gnome_object_construct (GNOME_OBJECT (cal), corba_cal);
 	return cal;
@@ -222,7 +237,7 @@ cal_construct (Cal *cal, GNOME_Calendar_Cal corba_cal)
  * @object: #GnomeObject that will wrap the CORBA object.
  *
  * Creates and activates the CORBA object that is wrapped by the specified
- * calendar @object.
+ * calendar client interface @object.
  *
  * Return value: An activated object reference or #CORBA_OBJECT_NIL in case of
  * failure.
@@ -242,6 +257,7 @@ cal_corba_object_create (GnomeObject *object)
 	CORBA_exception_init (&ev);
 	POA_GNOME_Calendar_Cal__init ((PortableServer_Servant) servant, &ev);
 	if (ev._major != CORBA_NO_EXCEPTION) {
+		g_message ("cal_corba_object_create(): could not init the servant");
 		g_free (servant);
 		CORBA_exception_free (&ev);
 		return CORBA_OBJECT_NIL;
@@ -252,69 +268,47 @@ cal_corba_object_create (GnomeObject *object)
 }
 
 /**
- * cal_add_listener:
- * @cal: A calendar.
- * @listener: A listener.
+ * cal_new:
+ * @backend: A calendar backend.
+ * @listener: A calendar listener.
+ *
+ * Creates a new calendar client interface object and binds it to the specified
+ * @backend and @listener objects.
  *
- * Adds a listener for changes to a calendar.  The specified listener object
- * will be used for notification when objects are added, removed, or changed in
- * the calendar.
+ * Return value: A newly-created #Cal calendar client interface object, or NULL
+ * if its corresponding CORBA object could not be created.
  **/
-void
-cal_add_listener (Cal *cal, GNOME_Calendar_Listener listener)
+Cal *
+cal_new (CalBackend *backend, GNOME_Calendar_Listener listener)
 {
-	CalPrivate *priv;
+	Cal *cal, *retval;
+	GNOME_Calendar_Cal corba_cal;
 	CORBA_Environment ev;
+	gboolean ret;
 
-	g_return_if_fail (cal != NULL);
-	g_return_if_fail (IS_CAL (cal));
-	g_return_if_fail (!corba_object_is_nil (listener));
+	g_return_val_if_fail (backend != NULL);
+	g_return_val_if_fail (IS_CAL_BACKEND (backend));
 
-	priv = cal->priv;
+	cal = CAL (gtk_type_new (CAL_TYPE));
+	corba_cal = cal_corba_object_create (GNOME_OBJECT (cal));
 
 	CORBA_exception_init (&ev);
-
-	GNOME_Unknown_ref (listener, &ev);
-	priv->listeners = g_list_prepend (priv->listeners, CORBA_Object_duplicate (listener, &ev));
+	ret = CORBA_object_is_nil (corba_cal, &ev);
+	if (ev._major != CORBA_NO_EXCEPTION || ret) {
+		g_message ("cal_new(): could not create the CORBA object");
+		gtk_object_unref (GTK_OBJECT (cal));
+		CORBA_exception_free (&ev);
+		return NULL;
+	}
 
 	CORBA_exception_free (&ev);
-}
 
-/**
- * cal_remove_listener:
- * @cal: A calendar.
- * @listener: A listener.
- *
- * Removes a listener from a calendar so that no more notification events will
- * be sent to the listener.
- **/
-void
-cal_remove_listener (Cal *cal, GNOME_Calendar_Listener listener)
-{
-	CalPrivate *priv;
-	CORBA_Environment ev;
-	GList *l;
-
-	g_return_if_fail (cal != NULL);
-	g_return_if_fail (IS_CAL (cal));
-
-	priv = cal->priv;
-
-	CORBA_exception_init (&ev);
-
-	/* FIXME: CORBA_Object_is_equivalent() is not what one thinks.  This
-	 * code could fail in situtations subtle enough that I don't understand
-	 * them.  Someone has to figure out the standard CORBA idiom for
-	 * listeners or notification.
-	 */
-	for (l = priv->listeners; l; l = l->next)
-		if (CORBA_Object_is_equivalent (listener, l->data)) {
-			GNOME_Unknown_unref (listener, &ev);
-			CORBA_Object_release (listener, &ev);
-			priv->listeners = g_list_remove_link (priv->listeners, l);
-			g_list_free_1 (l);
-			break;
-		}
+	retval = cal_construct (cal, corba_cal, backend, listener);
+	if (!retval) {
+		g_message ("cal_new(): could not construct the calendar client interface");
+		gtk_object_unref (cal);
+		return NULL;
+	}
 
-	CORBA_exception_free (&ev);
+	return retval;
 }
diff --git a/calendar/pcs/cal.h b/calendar/pcs/cal.h
index 959331595c..80d349d44d 100644
--- a/calendar/pcs/cal.h
+++ b/calendar/pcs/cal.h
@@ -1,4 +1,4 @@
-/* GNOME calendar object
+/* GNOME calendar client interface object
  *
  * Copyright (C) 2000 Helix Code, Inc.
  *
@@ -25,6 +25,7 @@
 #include <libgnome/gnome-defs.h>
 #include <bonobo/gnome-object.h>
 #include "gnome-calendar.h"
+#include "cal-common.h"
 
 BEGIN_GNOME_DECLS
 
@@ -36,9 +37,6 @@ BEGIN_GNOME_DECLS
 #define IS_CAL(obj)         (GTK_CHECK_TYPE ((obj), CAL_TYPE))
 #define IS_CAL_CLASS(klass) (GTK_CHECK_CLASS_TYPE ((klass), CAL_TYPE))
 
-typedef struct _Cal Cal;
-typedef struct _CalClass CalClass;
-
 struct _Cal {
 	GnomeObject object;
 
@@ -52,14 +50,13 @@ struct _CalClass {
 
 GtkType cal_get_type (void);
 
-Cal *cal_construct (Cal *cal, GNOME_Calendar_Cal corba_cal);
+Cal *cal_construct (Cal *cal,
+		    GNOME_Calendar_Cal corba_cal,
+		    CalBackend *backend,
+		    GNOME_Calendar_Listener listener);
 GNOME_Calendar_Cal cal_corba_object_create (GnomeObject *object);
 
-Cal *cal_new (char *uri);
-Cal *cal_new_from_file (char *uri);
-
-void cal_add_listener (Cal *cal, GNOME_Calendar_Listener listener);
-void cal_remove_listener (Cal *cal, GNOME_Calendar_Listener listener);
+Cal *cal_new (CalBackend *backend, GNOME_Calendar_Listener listener);
 
 POA_GNOME_Calendar_Cal__epv *cal_get_epv (void);