Hi guys,
My browser application needs to receive a notification from javascript.
I basically followed nsSample example. The way I did is that
1. create/implement a nsINotifListener, the interface like
[scriptable, uuid(913C5060-A929-11d5-B85D-00105A69E379)]
interface nsINotifListener : nsISupports
{
void notif(in string msg);
};
2. create/implement a nsINotifService, the interface like
[scriptable, uuid(5A0EC100-A928-11d5-B85D-00105A69E379)]
interface nsINotifService : nsISupports
{
void addNotifListener(in nsINotifListener listener);
void removeNotifListener(in nsINotifListener listener);
void removeNotifListeners();
void notif(in string msg);
};
the service has method
NS_IMETHODIMP nsNotifService::Notif(const char *msg)
{
if(aListener)
{
aListener->Notif(msg);
}
return NS_OK;
}
which dispatches the notif to the listener.
3. create a component info, like
static nsModuleComponentInfo components[] =
{
{ "Notif Service",
NS_NOTIFSERVICE_CID,
NS_NOTIFSERVICE_CONTRACTID,
nsNotifService::Create }
};
NS_IMPL_NSGETMODULE("nsNotifServiceModule", components)
4. build the notifservice as dll
5. create a test html page, like
<html>
<script language="javascript">
netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
var nserv =
Components.classes["@mozilla.org/notifservice;1"].createInstance();
nserv = nserv.QueryInterface(Components.interfaces.nsINotifService);
dump("notifservice = " + nserv + "\n");
function notif()
{
netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
nserv.Notif("js notif");
}
</script>
<form name="form">
<input type="button" value="Get" onclick="notif();">
<form>
</html>
6. implement the browser app to subclass the listener interface and
instantiate
the notifservice on startup, like
nsresult rv;
notifserv = do_CreateInstance(NS_NOTIFSERVICE_CONTRACTID, &rv);
if(NS_FAILED(rv))
{
return;
}
notifserv->AddNotifListener(p);
I expect:
At the runtime, my browser application loads the notifservice first and
add itself as a listener to the service. By the time, I assume the
notifservice
remaining in memory. Then my browser app loads the test html page which
loads
the notifservice as well. Because the notifservice already registered in
memory,
I assume the xpconnect only increases the reference count rather than
creates
a new instance again. When I click the button in html, it will call the
javascript function which in turn calls on the notifservice's method. The
method
dispatches the call to the listener.
The browser app loads the notifservice and registeres itself as a listener
successfully as I debug through but the it seems nothing happen at
javascript side.
The breakpoint never reaches nsNotifService's notif method. It seems tell me
that
loading the notifservice in js isn't successfully. I don't think I have to
implement something like nsSample.js because I have c++ implemention, do I!?
To instantiate a xpcom component and call on the component from javascript,
what extra work should be done? Or, is the way I thought and did wrong?
I have also searched the similar topics in the newsgroup against my
implementation
and didn't see any particular problem with my implementation.
By the way, the "dump" js method didn't output to the debug console.
What should be set in order to see some info in the console?
Thanks
