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 …

+

+

My proposal for the Google Summer of Code 2006 has been accepted!

Name
----
   Christophe 'CSCMEU' Nowicki
 
Email
-----
    cscm at meuh dot dyndns dot org

Project Title
=============
    Mozilla and D-BUS Integration

Synopsis
--------
   The goal of this project is to allow Mozilla components to communicate
   through D-BUS ( www.freedesktop.org/wiki/Software/dbus )
   in order to allow better integratation in the Linux Desktop.

Benefits to the Mozilla Community
---------------------------------
    Better Integration of the Mozilla Suite Inside the Linux Desktop:
        - possiblity to send and recive messages through D-BUS from Mozilla
        components via XPCOM objects.
        - possiblity to use existants projects like:
            - Avahi ( avahi.org ) for Zeroconf support,
            - Beagle  ( beaglewiki.org ) the query directly beagle from the
            Mozilla Search Bar
            - Other, see list of software supporting D-BUS :
            www.freedesktop.org/wiki/Software_2fDbusProjects
        - possiblity to provide Mozilla services via D-BUS.

Deliverables
------------
    - source code of the XPCOM compents under the MPL license
    - documentation of the API
    - sample extension using the XPCOM implementation

Project Details
---------------

    XPCOM Component
    ~~~~~~~~~~~~~~~

    The first step of the project is to allow Mozilla components
    to make D-BUS call :

        var DBUS = new Components.Constructor('@mozilla.org/dbus;1', 'nsIDBUS')
        var dbus = new DBUS()
        var bus = dbus.SystemBus()

        var dbus_obj = bus.get_object('org.freedesktop.DBus',
            '/org/freedesktop/DBus')
        var dbus_iface = dbus.Interface(dbus_obj, 'org.freedesktop.DBus')

        dump( dbus_iface.ListNames() )

    My API will be inspired by the Python D-BUS API.

    Javascript Events
    ~~~~~~~~~~~~~~~~~

    The second step would by to integrate D-BUS inside the Java Script event
    loop.

    Difficulties
    ~~~~~~~~~~~~
    The technical difficulties of the project are :
        - the type mapping between the D-BUS API and Mozilla
        - memory management, in order to avoid memory leaks
        - manage DBUS communication channels between componants instances.

    The cons against this project are :
        - D-BUS is not working (yet) on Microsoft Windows 
            (comming soon)


Project Schedule
================
   The project is sized for one person and should be finished at the end of
   Summer Of Code. I estimate the working time like that:

    - write specifications of the project ( 10 days )
    - analyse the mozilla architecture / source code to plugin the feature
    nicely ( 10 days )
    - write the XPCOM components ( 15 days )
    - write the documentation ( 5 days )
    - write sample application ( 5  days )
    - debug and integrate the components in the Mozilla source tree, code
    review, etc ( 10 days )

    Total estimate : 55 days witch is more or less 3 working month.

Bio
===
    I'am a French student in computer science from EPITECH ( www.epitech.net )
    involved in the free and opensource mouvement:

        - as an Debian 'Power User' : reporting bug, making packages, writing documentation and helping users on forums
        - as an Developper of the FANI project ( www.fani-project.org ),
        it's an multi operating systems network installer writen in
        XUL and Python.
        - as an half-time engineer and developper working for Easter-eggs
        ( www.easter-eggs.com ), an opensource services company involved
        in free software developpement ( see our projects on
        labs.libre-entreprise.org ).

    My curriculum-vitae is available on my blog: www.csquad.org/curriculum-vitae

Best Regards,