Description
BonoboObject provides an easy to use way of writing CORBA servers. It
drastically simplifies the issues of epv and vepv construction by
automating these, and automatically instantiates a CORBA_Object on
g_object_new. This removes clutter from construction time. For
libbonobo-2.0, it strongly deprecates BonoboXObject.
Again if you are looking to implement a CORBA interface you want to
see BonoboXObject.
The Bonobo::Unknown interface (wrapped by
BonoboObject) is the foundation for the component system: it provides
life cycle management for objects as well as service discovery.
The Bonobo interfaces are all based on the
Bonobo::Unknown interface. This
interface is very simple and provides two basic services:
object lifetime management and object
functionality-discovery. This interface only contains three
methods, here it is:
module Bonobo {
interface Unknown {
void void ref();
void void unref();
Object query_interface (in string repoid);
};
};
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The ref() and unref()
methods are used to control the lifetime of an object. The
query_interface method is used to discover
optional functionality provided by the object implementation.
The lifetime management is based on reference counting: when a
component is initially launched, it starts life with a reference
count of one. This reference is held by the component invoker.
Each time a reference is kept to this object (say, you store a
copy of the object in an array), the reference count is
incremented. Every time a reference goes out of scope, the
reference count needs to be decremented. When the reference
count reaches zero, the component knows that there are no
outstanding references to it, and it is safe to shutdown. At
this point, the component shuts down.
It is possible to ask an object which implements the
Bonobo::Unknown interface if it supports
other CORBA interfaces. For example, it would be possible to
ask an object whether it supports the
"IDL:Bonobo/EmbeddablePrint:1.0" interface to find out if it is
possible to print its contents. If the return value from
invoking the query_interface method on the
interface is CORBA_OBJECT_NIL, then we know that the requested interface
is not supported. Otherwise, we can invoke
IDL:Bonobo/EmbeddablePrint:1.0 methods on the returned CORBA
Object.
Clients of the query_interface method use
it to discover dynamically if a component supports a given
interface. Sometimes the client code would require a specific
interface to exist, but many times it is possible to operate in
a "downgraded" mode. You should design your code to be able to
cope with the lack of interfaces in objects. This will allow
your program to deal with more components, and this also allows
components to work in more situations.
For example, a help browser can load an HTML renderer component and
ask this component which sort of features are supported by it:
stop_animations (BrowserHTML html)
{
BrowserControl control
control = html->query_interface ("IDL:Browser/Control:1.0");
if (control)
control->stop_animations();
}
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The return value of the query_interface invocation contains a
reference to a CORBA object that is derived from the
Bonobo::Unknown interface or
CORBA_OBJECT_NIL if the interface is not supported by the
object. And this interface would have been already
ref()ed before it was returned. It is up
to the caller to call unref() when they are
done using the interface.
BonoboObject implements the Bonobo::Unknown interface and exports the
implementations of the methods in this class to simplify creating
new objects that inherit from Bonobo::Unknown. This base object
provides default implementations for the ref, unref and
query_interface methods.
Other implementations reuse this implementation by listing on their
VEPV tables the bonobo_object_epv entry point vector.
The Bonobo::Unknown interface is inspired
by the Microsoft COM IUnknown interface
but it has been translated into the CORBA world.
Details
BONOBO_OBJECT_TYPE
#define BONOBO_OBJECT_TYPE BONOBO_TYPE_OBJECT /* deprecated, you should use BONOBO_TYPE_OBJECT */ |
Returns the GtkType for the BonoboObject object.
BONOBO_OBJREF()
#define BONOBO_OBJREF(o) (bonobo_object_corba_objref(BONOBO_OBJECT(o))) |
BonoboObjectPOAFn ()
void (*BonoboObjectPOAFn) (PortableServer_Servant servant,
CORBA_Environment *ev); |
struct BonoboObjectPrivate
struct BonoboObjectPrivate; |
Private information kept by the BonoboObject. This should not be
used by BonoboObject users.
BonoboObjectHeader
typedef struct {
GObject base; /* pointer + guint + pointer */
BonoboObjectPrivate *priv; /* pointer */
guint object_signature; /* guint */
} BonoboObjectHeader; |
BONOBO_OBJECT_HEADER_SIZE
#define BONOBO_OBJECT_HEADER_SIZE (sizeof (BonoboObjectHeader)) |
BONOBO_OBJECT_SIGNATURE
#define BONOBO_OBJECT_SIGNATURE 0xaef2 |
BONOBO_SERVANT_SIGNATURE
#define BONOBO_SERVANT_SIGNATURE 0x2fae |
BonoboObject
typedef struct {
/* A GObject and its signature of type BonoboObjectHeader */
GObject base; /* pointer + guint + pointer */
BonoboObjectPrivate *priv; /* pointer */
guint object_signature; /* guint */
/* A Servant and its signature - same memory layout */
POA_Bonobo_Unknown servant; /* pointer + pointer */
guint dummy; /* guint */
Bonobo_Unknown corba_objref; /* pointer */
guint servant_signature;
} BonoboObject; |
BonoboObjectClass
typedef struct {
GObjectClass parent_class;
/* signals. */
void (*destroy) (BonoboObject *object);
void (*system_exception) (BonoboObject *object,
CORBA_Object cobject,
CORBA_Environment *ev);
BonoboObjectPOAFn poa_init_fn;
BonoboObjectPOAFn poa_fini_fn;
POA_Bonobo_Unknown__vepv *vepv;
/* The offset of this class' additional epv */
int epv_struct_offset;
PortableServer_ServantBase__epv base_epv;
POA_Bonobo_Unknown__epv epv;
} BonoboObjectClass; |
bonobo_object_add_interface ()
Adds the interfaces supported by newobj to the list of interfaces
for object. This function adds the interfaces supported by
newobj to the list of interfaces support by object. It should never
be used when the object has been exposed to the world. This is a firm
part of the contract.
bonobo_object_query_local_interface ()
bonobo_object_query_interface ()
Bonobo_Unknown bonobo_object_query_interface
(BonoboObject *object,
const char *repo_id,
CORBA_Environment *opt_ev); |
bonobo_object_corba_objref ()
Bonobo_Unknown bonobo_object_corba_objref (BonoboObject *object); |
bonobo_object_dup_ref ()
Bonobo_Unknown bonobo_object_dup_ref (Bonobo_Unknown object,
CORBA_Environment *opt_ev); |
This function returns a duplicated CORBA Object reference;
it also bumps the ref count on the object. This is ideal to
use in any method returning a Bonobo_Object in a CORBA impl.
If object is CORBA_OBJECT_NIL it is returned unaffected.
bonobo_object_release_unref ()
Bonobo_Unknown bonobo_object_release_unref (Bonobo_Unknown object,
CORBA_Environment *opt_ev); |
This function releases a CORBA Object reference;
it also decrements the ref count on the bonobo object.
This is the converse of bonobo_object_dup_ref. We
tolerate object == CORBA_OBJECT_NIL silently.
bonobo_object_ref ()
gpointer bonobo_object_ref (gpointer obj); |
Increments the reference count for the aggregate BonoboObject.
bonobo_object_idle_unref ()
void bonobo_object_idle_unref (gpointer obj); |
bonobo_object_unref ()
gpointer bonobo_object_unref (gpointer obj); |
Decrements the reference count for the aggregate BonoboObject.
bonobo_object_set_immortal ()
void bonobo_object_set_immortal (BonoboObject *object,
gboolean immortal); |
bonobo_object_trace_refs ()
gpointer bonobo_object_trace_refs (gpointer obj,
const char *fn,
int line,
gboolean ref); |
bonobo_object_dump_interfaces ()
bonobo_object_check_env ()
void bonobo_object_check_env (BonoboObject *object,
CORBA_Object corba_object,
CORBA_Environment *ev); |
This routine verifies the ev environment for any fatal system
exceptions. If a system exception occurs, the object raises a
"system_exception" signal. The idea is that GObjects which are
used to wrap a CORBA interface can use this function to notify
the user if a fatal exception has occurred, causing the object
to become defunct.
BONOBO_OBJECT_CHECK()
#define BONOBO_OBJECT_CHECK(o,c,e) |
Checks if the exception in e needs to be signaled. If so, then
the proper exception signal is generated on the BonoboObject object
o for the CORBA reference c.
bonobo_unknown_ping ()
gboolean bonobo_unknown_ping (Bonobo_Unknown object,
CORBA_Environment *opt_ev); |
Pings the object object using the ref/unref methods from Bonobo::Unknown.
You can use this one to see if a remote object has gone away.
bonobo_object_list_unref_all ()
void bonobo_object_list_unref_all (GList **list); |
This routine unrefs all valid objects in
the list and then removes them from list if
they have not already been so removed.
bonobo_object_slist_unref_all ()
void bonobo_object_slist_unref_all (GSList **list); |
bonobo_object ()
This function can be passed a BonoboObject * or a
PortableServer_Servant, and it will return a BonoboObject *.
bonobo_object_fast()
#define bonobo_object_fast(o) |
bonobo_object_from_servant()
#define bonobo_object_from_servant(s) ((BonoboObject *)(((guchar *) (s)) - BONOBO_OBJECT_HEADER_SIZE)) |
bonobo_object_get_servant()
#define bonobo_object_get_servant(o) ((PortableServer_Servant)((guchar *)(o) + BONOBO_OBJECT_HEADER_SIZE)) |
bonobo_type_unique ()
This function is the main entry point for deriving bonobo
server interfaces.
bonobo_type_setup ()
This function initializes a type derived from BonoboObject, such that
when you instantiate a new object of this type with g_type_new the
CORBA object will be correctly created and embedded.
BONOBO_TYPE_FUNC_FULL()
#define BONOBO_TYPE_FUNC_FULL(class_name, corba_name, parent, prefix) |
BONOBO_TYPE_FUNC()
#define BONOBO_TYPE_FUNC(class_name, parent, prefix) |