Embedded

DBus - How to pass dict as parameter

2010-11-18T06:02:00.000-08:00

This tutorial is designed for those ones that need DBus but suffer a lot to find documentation even about simple things, such as how to pass a dictionary as parameter.

Initially, I had to invoke a Bluez method that needs a dictionary as parameter. But how could I do it? It not easy at all to find a detailed documentation about it and I had to look for a solution at BlueZ source code.

In this case, I'm using the newest BlueZ Health API (support for HDP/MCAP). The following piece of code shows


static char *start_health_session(DBusConnection *conn)
{

  DBusMessage *msg, *reply;
  DBusMessageIter args;
  DBusError err;
  const char *reply_path;
  char *path;

  msg = dbus_message_new_method_call("org.bluez", 
                                     "/org/bluez", 
                                     "org.bluez.HealthManager",
                                     "CreateApplication");

  if (!msg) {
      printf(" network:dbus Can't allocate new method call\n");
      return NULL;
  }

  // append arguments

  dbus_message_iter_init_append(msg, &args);

  if ( !iter_append_dictionary(&args, DATA_TYPE_VALUE, 
                                          ROLE_VALUE,
                                          DESCRIPTION_VALUE, 
                                          CHANNEL_TYPE_VALUE) ) {
      printf(" network:dbus Can't append parameters\n");
      dbus_message_unref(msg);
      return NULL;
  }

  dbus_error_init(&err);

....
}

A DBus dict type needs a message iterator, which is properly initialised before it is used.

Once the message iterator is properly created, let's open it and add tuples to it.


static int iter_append_dictionary(DBusMessageIter *iter, 
                                  dbus_uint16_t dataType,
                                  const char *role,
                                  const char *description,
                                  const char *channelType)
{
  DBusMessageIter dict;

  dbus_message_iter_open_container(iter, DBUS_TYPE_ARRAY,
            DBUS_DICT_ENTRY_BEGIN_CHAR_AS_STRING
            DBUS_TYPE_STRING_AS_STRING DBUS_TYPE_VARIANT_AS_STRING
            DBUS_DICT_ENTRY_END_CHAR_AS_STRING, &dict);

  dict_append_entry(&dict, "DataType", DBUS_TYPE_UINT16, &dataType);

  dict_append_entry(&dict, "Role", DBUS_TYPE_STRING, &role);

  dict_append_entry(&dict, "Description", DBUS_TYPE_STRING, &description);

  dict_append_entry(&dict, "ChannelType", DBUS_TYPE_STRING, &channelType);

  dbus_message_iter_close_container(iter, &dict);
}

At first, you have to open the container and specify the data type of each tuple. In this case, the dictionary consists of tuples <"DataType",uint16>, <"Role",string>, <"Description",string>, and <"ChannelType",string>. Once the value data type for each tuple varies (uint16 or string), we declare it as a variant. Therefore, the dictionary data type definition is:


DBUS_DICT_ENTRY_BEGIN_CHAR_AS_STRING
DBUS_TYPE_STRING_AS_STRING DBUS_TYPE_VARIANT_AS_STRING
DBUS_DICT_ENTRY_END_CHAR_AS_STRING

Finally, you simply add the basic data type to message iterator (the dictionary itself).


static void append_variant(DBusMessageIter *iter, int type, void *val)
{
  DBusMessageIter value;
  char sig[2] = { type, '\0' };

  dbus_message_iter_open_container(iter, DBUS_TYPE_VARIANT, sig, &value);

  dbus_message_iter_append_basic(&value, type, val);

  dbus_message_iter_close_container(iter, &value);
}

static void dict_append_entry(DBusMessageIter *dict,
   const char *key, int type, void *val)
{
  DBusMessageIter entry;

  if (type == DBUS_TYPE_STRING) {
    const char *str = *((const char **) val);
    if (str == NULL)
      return;
  }

  dbus_message_iter_open_container(dict, DBUS_TYPE_DICT_ENTRY,
                                   NULL, &entry);

  dbus_message_iter_append_basic(&entry, DBUS_TYPE_STRING, &key);

  append_variant(&entry, type, val);

  dbus_message_iter_close_container(dict, &entry);
}

CUnit on ARM platforms.

2010-08-16T10:33:00.000-07:00

Let's use this stuff :P Anyway, it's a good tool and I need to put some ideas anywhere.

So, today's tip is how to compile your CUnit tests on Embedded platforms - in this case, on a N900 (ARM) with MeeGo installed on it.

You should download the CUnit source code from http://sourceforge.net/projects/cunit/ (I only tested versions 2.0.X and 2.1.X). The process is very simple: download the code, copy to your development environment, and build it (./bootstrap && make). However, things are not soooo easy as it seems :P

Probably, you'll face problems at initial steps.

If you have any problems on , execute the following command to change modification time/time:


find /path/to/files -exec touch {} \;

It seems to work.

Give us your oppinion!

2009-08-11T05:05:00.000-07:00

IDE Integration 2nd edition is comming soon, including new PluThon Eclipse product. It comes with new and interesting features, such as ltrace integration. However, we know that Maemo community has a lot of valuable feedback and ideas that certainly improves PluThon and any other IDE Integration components (ESbox, PC Connectivity, etc.)

Please, visit PluThon 2nd edition web site, check how features you´d see implemented on PluThon and provide a feedback to eclipse-integration AT maemo DOT org. Your comments are welcomed!

Pluthon - how to easily create debian packages

2009-07-07T05:29:00.000-07:00

Hi,

IDE Integration Beta 2 has been released, including Pluthon Beta 2 release :)

Since PluThon uses Internet Tablet environment as programming environment, most of programming tasks (except coding) are performed on your device. Then, launching/debugging are done directly on Internet Tablet.

Generally, we use distutils utilities for pymaemo to generate Debian packages on device. On this method, you need to create a setup.py script and insert a lot of information regarding to your project. You may face some problem during your first experience on debian package creation or even you may forget to insert some important information. Once your setup.py is properly created, you need to generate your debian package using pymaemo python interpreter.

PluThon also helps you to create Debian package from your project with distutils for maemo utilities. With helpfull graphical wizards, you can create Debian packages from your projects at a glance ;) For more information about this interesting feature, you can check it at PluThon User´s Help.

Try PluThon and give us your feedback!!

The easiest way to install Maemo SDK environment

2009-06-14T16:40:00.000-07:00

ESbox Beta 1 release comes with a very interesting feature: graphical installers for Scratchbox 1, Scratchbox (1 and 2) targets and Nokia binaries (which are mandatory for Fremantle, for example). ESbox also flashes your Internet Tablet with latest image.

For more information about these features, you can visit Forum Nokia Blog page.

Customizing your Maemo SDK Virtual Image

2009-05-24T16:15:00.000-07:00

Hi,

Maemo Eclipse Integration 2nd Edition Beta 1 was just released, including Maemo SDK Virtual Image :)

On a recent post on Forum Nokia blog, I described about how Maemo SDK VM can help you to properly configure your Maemo programming environment, specially on those cases that you have to configure a lot of machines for a Maemo programming workshop, for example.

In addition, if you want to customize your Maemo SDK VM for a specific case (for example, distribute an old Maemo SDK release), you can check here the requirements list we've considered to provide Maemo SDK VM version 0.10.

Promoting competence on Nokia mobile platforms

2009-05-18T19:01:00.000-07:00

Embedded Lab has launched the 2nd edition of Effort Competition (website on portuguese), an interesting challenge for undergraduate and graduate students. The main objective is to make that students explore Nokia mobile platforms (maemo, S60, ...) to generate interesting and innovative projects.

The winners will receive Nokia 7310 Supernova devices as prize :) Unfortunately, Effort Competition 2nd edition subscriptions are over, but keep on eye on it - 3rd edition is coming!

You can also check more comments on Forum Nokia Blog.

IDE Integration for maemo development

2009-05-01T20:10:00.000-07:00

Hi,

are you looking for an IDE to help you on maemo programming? Or a tool that helps you to get connected with device using different communication interfaces of Internet Tablet (Bluetooth, WLAN or USB)?

IDE Integration project provides a full feature environment with IDEs, programming environments and conectivity tools. Therefore, you can start maemo development a lot quicker (and much easier :).

Take a look at this post on Forum Nokia Blog page.

Mica Framework

2009-04-26T16:17:00.000-07:00

Maybe, you've already heard about ESbox and PluThon IDEs for maemo development. They have a lot of things in common: remote launching/debugging, Debian package generation/installation, and much more. But why two different products? Because ESbox needs Scratchbox, but PluThon does not.

That's right... I got it. But since ESbox and PluThon have some features in common, why don't we create a common framework? And so we did :)

Mica (Maemo Integration Common Architecture) framework does not only provide a common architecture for ESbox and PluThon, but also a common plugin architecture for developing maemo development environments based on Eclipse.

If you're planning to create a plugin for Eclipse framework in order to help other maemo developers, you can use Mica. On its official site, you can access useful documentation such as architecture and developer's guide. If you need any other example, you can check Mica-Plugins project. For example, a plugin that finds the Internet Tablets available.

You, as Mica/ESbox/PluThon user/developer, can contribute a lot with such projects! Please, report your suggestions, doubts and any other comments to eclipse-integration at maemo dot org.

ESbox/PluThon 2.0.0M1 Released!

2008-11-14T10:43:00.001-08:00

Since the lastest release of ESbox/PluThon (on July 2008), IDE integration team haven't released any other version of the projects (ESbox, PluThon and PC Connectivity). Then, since July 2008, we have been planning, designing and developing the newest 2nd Edition of IDE Integration.

ESbox/PluThon 2.0.0M1 have been released today, including new functionalities and a huge, interesting and well-done refactoring of architecture. Now, both ESbox and PluThon share a common framework, which was designed also to be used as developing maemo development environments based on Eclipse.

Besides ESbox and PluThon, IDE Integration also consists of PC connectivity (http://garage.maemo.org/projects/pc-connectivity) and maemo SDK virtual image (http://garage.maemo.org/projects/maemovmware).

One interesting feature of this first alpha release is support the integration with RSE Eclipse project, which provides heterogeneous remote resources through a concept of pluggable subsystems.

Back to the blog

2008-11-02T18:20:00.000-08:00

More than 2 months since my last post in this blog!! But we're back!

To start this new "season", I introduce to you Forum Nokia (http://forum.nokia.com). It consists of a consistent and complete site for Nokia developers. There, you can find information, documentation, tools and SDKs to start developing applications for Symbian, WRT, Python S60, maemo and all the others Nokia platforms.

In addition, Forum Nokia often launches competitions in order to call developers to participate by writing interesting articles, testing new APIs and providing inovative solutions based on Nokia platforms. Winners receive interesting prices ($$ and new devices!) and also they become known contributtors on Symbian, Python S60, Web, WRT and maemo communities :)

Yeah Curitiba! It was great... daí :)

2008-06-08T10:23:00.000-07:00

The Week of Mobility on Curitiba was the most interesting experience we had so far: a very nice group, with students that were looking for new features on maemo platform every time. The results were also amazing!! Translators, media players, applications that synchronizes Internet Tablet and desktop contents, games, OCR... are just some examples of applications developed by maemo students during the last days of workshop. Thanks a lot for Myriam, Anelise and Keiko. For more information (including photos and videos), visit http://semanadamobilidade.blogspot.com

Week of Mobility

2008-05-26T06:50:00.001-07:00

Brazil! The red dots are the cities where INdT had promoted several talks, trainings and also the programming arena at International Forum of Free Software. More information, visit http://semanadamobilidade.blogspot.com

Next city: Curitiba

2008-05-24T07:09:00.000-07:00

Week of Mobility is up and running!! Our new destination is Curitiba, a nice city in South of Brazil. I´m very anxious about this event: we´ll certainly produce great results, such as interesting applications! As on previous editions, the Week of Mobility on Curitiba consists of talks about maemo platform, embedded Linux and Python for S60. There´re also trainings on maemo and Python for S60. The students will have access to Nokia N800 Internet Tablet to test their applications, that are developed during the training. If you´re interested in it and would like more information about it, visit http://semanadamobilidade.blogspot.com .

ESbox: almost there

2008-05-05T13:38:00.000-07:00

We are just performing some minor changes in ESbox for finally releasing version 1.4, which is working quite fine. I got realized how a tool such ESbox helps the programmer a lot just some days ago. On maemo workshops promoted by INdT, I could see how much newbies on maemo platform suffered for running a simple "Hello World" application even in Python.

In fact, the problem is not just how to compile the application, but also how to install, configure and use a command-line-based programming environment. It is important to provide good development tool to support a certain open source technology, otherwise its community will not grow up considerably - ESbox comes to solve such problem. For more information about it, visit http://esbox.garage.maemo.org/.

Thanks a lot Ed Swartz and Ling Wang for such great job and also the valuable lessons about Eclipse plug-in development.

Previous Post on Portuguese - INdT promove Semana de Mobilidade no Brasil

2008-04-30T10:58:00.000-07:00

O Instituto Nokia de Tecnologia (INdT) está promovendo a Semana da Mobilidade em várias cidades do Brasil. O evento consiste em palestras interessantes e minicursos sobre a plataforma maemo e Python para S60, ambas tecnologias desenvolvidas pela Nokia para dispositivos móveis. As inscrições são de graça!! Para maiores informações sobre inscrições, programação, local e duração podem ser encontradas no blog http://semanadamobilidade.blogspot.com/.

INdT promotes "Weeks of Mobility" in Brazil

2008-04-30T10:47:00.000-07:00

Nokia Institute of Technology (INdT) promotes "Weeks of Mobility" on several cities of Brazil. The event consists of interesting lectures and workshops about maemo platform and Python for S60 - both have been developed by Nokia to be used on mobile devices. INdT is offering it for free!! For more information about the event, such as programming and subscription, visit http://semanadamobilidade.blogspot.com/.

Python Development for maemo platform

2008-04-28T13:45:00.000-07:00

I've posted a tutorial in Forum Nokia wiki that helps to get start with Python applications for maemo 4.x. Follow this link. It is also available a Portuguese version here.

INdT Programming Arena Contest at FISL

2008-04-13T11:10:00.000-07:00

Nokia Institute of Technology promotes programming contests in cooperation with Forum Nokia at FISL 2008 Programming Arena Contest

The winners will receive Nokia N95 and Nokia N800 devices as prizes. Forum Nokia will also promote some lectures to guide developers that want to contribute with its projects.

This is the first time that Nokia Institute of Technology (Instituto Nokia de Tecnologia - INdT) will participate in International Forum of Free Software (Fórum Internacional de Software Livre - FISL) that will happen from April 17^th to 19^th at Porto Alegre, Brazil. In partnership with Forum Nokia, an on-line community with more than 3 million of subscribed developers, the Institute promotes programming challenges in FISL Programming Arena and the best ones win Nokia N95 and Internet Tablets Nokia N800.

The challenges consist of programming contests that take into account programming an developing technical skills. The competition, which can be performed by only one programmer or by a team, will be integrated into open source projects for mobile platforms.

There are two phases: qualifying and insanifying. At qualifying phase, some simple task help the teams to get closer with Python language, Symbian OS and the platform API. Those ones that achieve the best results are classified to the next phase. The final result is a contribution to an open source project that can continue even after FISL.

Daniel Rocha, manager of Forum Nokia at Brasil, will present the lecture “Nokia – Open Source Initiatives and Projects for Smartphones”. He intents to show the last Nokia initiatives on the open source world, such as Python for S60, Open C, Maemo, Mobile Web Server and other important projects. The main reason for the talk is to guide the developers on how to become involved in such projects, how to port open source code to S60 smartphones and how to contribute with Forum Nokia open source projects.

Besides being part of Arena, the INdT will also participate of FISL in order to identify potential employer candidates. “We know that the best professionals of open source, the main research upstream of INdT - Recife, are on FISL. The competition atmosphere is the environment to evaluate the abilities of the candidates for possible jobs at INdT”, says Vanessa Nalesso, HR manager of INdT.

Open source world and universities

2008-04-10T13:28:00.000-07:00

Finally, my first post!

Last week, I had a very interesting discussion about open source world with some guys from a Brazilian public university and I got surprised with the comments they made. I've been thinking a bit more about this question.

I got realized how some universities are still to far away from open source projects and subjects, such as licensing and team management. Some professors are so involved in academic world that they forget how the student can learn if they'd be part of an open source project. In fact, most of them (wrongly) suppose that open source software is a mass: no documentation is available, projects with just a few features, lots of bugs, etc. Fortunately, the world is changing :). There're lots of projects really interesting, cleanly designed, full of useful features for user and also well documented. Becoming involved in open source projects is not a waste of time... they have been taken seriously.

I don't know why most of students think that you can't make money with open source projects and even learn a lot about interesting technologies, such as communication protocols, software engineering, hardware elements, and much more. Riehle shows how open source software impacts the economic behavior of stakeholders in the software ecosystem and we can understand how software companies make money with open source products. The rules are different, then we need specific methodologies to develop open source projects. Most of software engineering we've learned in universities may not be applied on open source software: the development is distributed, the "user" is a community (if it exists), how we can define deadlines, milestones, ...

The most important "post-undergraduate" experiences I had so far was those ones that involved open source projects: LLVM, Eclipse, ESbox, ... I remembered a lot of some software engineering classes on which we discussed how hard is to maintain and keep the software reusable. Also those compiler classes were really useful in LLVM ARM JIT support implementation.

So, don't think twice: we can learn a lot with open source projects and also makes a curriculum vitae stand out.

Newbie on blog's world

2007-11-08T18:42:00.000-08:00

Let's write something interesting here...