Christophe Nowicki

Sorry, I did not update my progress since one month.

Here is my current progress on that project :

• Signals are supported, you can send en receive signals
• Introspection XML data is now parsed by my component
• I’ve wrote an dbus-viewer clone in XUL
• I’ve integrated Threads

But I did not release a 0.1 version because my wrapper produce a dead lock :
If you listen for a signal and call a remote method, you program get locked.
This is a common usage of D-BUS and I think that I can’t release my work without it.

This problem is caused by libdbus witch is not threads “aware” and because I don’t have a shared
lock between my threads.

Havoc Pennington explained me howto solve this issue : integrate libdbus inside my mainloop as glib as done :

GLIB Mainloop integration

This integration is hard because D-BUS is using UNIX file handle and NSPR does not provide functions to handle it.

I did not expect so many technical difficulties, but I stay motivated.
I continue to work on my project (after the end of the summer of code) and I will release version 0.1 as soon as the dead lock issue is solved.

Ok, boys and girls, version 0.1 is comming! ;0)

This week I was focused on documentation :

• I’ve started the initial draft of the DBuzilla Tutorial, the goal of this document is to quickly explain howto use the API. I’am inspred by Matthew Johnson’s “Using the DBUS C API” article, which I found very clear.
• Updated the API Class diagram.
• Setup LXR for API reference.
• Update the Wiki.

I’ve made progress in the wrapper code :

• Mixed array are now supported : Array(1, ‘string’, 2.3)
• Threads are now wrapped.
• Callback are now handled, but not fully : It’s working for the XPCOM part but D-BUS does not call my handle back.

I will release version 0.1 when I find an issue to the callback problems. (I’d like to see asynchronous call and signals managed by 0.1).

My current progress on the project is disappointing, I am blocked on the value returned by an method call.
I can make a basic D-BUS method call from Javascript, but I’am unable to get his return value.
Here is the sample of code :

var comp = Components.classes[nsDBUSContactID];
var dbus = comp.createInstance();
var session = dbus.SessionBus();
var iface = session.FindInterface('org.mozilla.TestService', '/',  'org.mozilla.TestInterface')
var ret = iface.Call('Hello')
dump('return value = ' . ret ) 

The ‘ret’ value can be of any kind of type (string, int, array, object, etc…).
I’ve found the javascript code for managing any type of return value from an XPCOM method, in the mozilla xml-rpc extension :

/* Create an instance of the given ContractID, with given interface */
function createInstance(contractId, intf) {
    return Components.classes[contractId].createInstance(Components.interfaces[intf])
}

/* return type */
function testReturn(type) {
    const SUPPORTSID = '@mozilla.org/supports-';
    var ret
    switch(type) {
        case 'INT32':
            ret = createInstance(SUPPORTSID + 'PRInt32;1', 
                'nsISupportsPRInt32')
            ret.data = 65
            break
        case 'STRING':
            ret = createInstance(SUPPORTSID + 'cstring;1', 
                'nsISupportsCString')
            ret.data = 'arf'
            break
        case 'DOUBLE':
            ret = createInstance(SUPPORTSID + 'double;1', 
                'nsISupportsDouble')
            ret.data = 2.4
            break
       ....
    }
    return ret;
}

I’ve wrote the C++ version of this code, but It does not work :
XPIDL prototype of my method :

nsISupports Test();

The C++ implementation :

NS_IMETHODIMP
nsDBusImpl::TestSupports(nsISupports **_retval) {
    nsresult rv;
    nsCOMPtr ret = 
        do_CreateInstance("@mozilla.org/supports-PRInt32;1", &rv);
    if (NS_FAILED(rv)) {
        return rv;
    }
    ret->SetData(42);
    // _retval = (nsISupports **) &ret; // Does not work
    // *_retval = ret;  // Segfault

    return NS_OK;
}

I’am stopped by this problem …

This feature is not well documented, so there is the configuration ligne to add in your /etc/dbus-1/system.conf file :

<listen>tcp:host=localhost,port=12434</listen>