Capturing Model Semantics with Dynamic Aspects

A couple of week ago I found an article about the Liskov Substitution Principle and the unavoidable reference to the circle/ellipse or square/rectangle problem.

I looked to the different solutions in the wikipedia page and I though than that was actually one of the "semantic problems" computers does not face very well. So I spend sometime thinking about this and my conclusion was that the solution will depend on the intended use of the classes in a given application or model.

Then I'd got the idea of using AOP and dynamic inheritance to implement the semantics for a given application as an orthogonal feature, keeping the class hierarchy as isolated as possible. In other words, to extend a given model with aspects that encapsulates the semantics behind it.

So, I tried to implement this idea using GNU/EDMA

Open Source Hardware Logo

Hi everybody!

The Open Hardware Summit want a logo for Open Hardware to be attached to the definition. Of course we love to participate, so these are our proposals:

New cover and content for Occam's Razor magazine

Hi everybody,

It's been a long time since my last entry. We did some stuff in the way hoping it comes soon the result...

Going to the point, as the title says, we have collaborated in another issue of OR the Techie Spanish magazine. This is issue 5 so congratulations from here!

BeagleBoard and Pandaboard in Occams's Razor 5

If you speak Spanish, or you can live with automatic translations, take a look to this open magazine, Occam's Razor. The lastest number includes an article about Open Hardware, featuring BeagleBoard and PandaBoard projects, and several other Open Hardware projects.

BeagleBoard based VRPN Nodes

VRPN is a great library to interface to a lot of input devices commonly used on Virtual Reality applications. From magnetic trackers to datagloves, the list of supported devices is quite long.

So, why do not use a BeagleBoard with a wifi interface as a VRPN server?. That could be very useful as the beagle is pretty small, has low power consumption (so it could run on batteries if needed) and enough CPU power to deal with most of the input devices supported by VRPN.

Wendy alpha relase


Our current simple-alpha-version of Wendy is available for download!. Wendy is a simple SDL application used to prototype our Pervasive Widgets (AKA Hermits).

You can download the source code from here. You will need the SDL, SDL_image and SDL_ttf development packages to compile it..

Here is the README for this version 0.1. It has been tried (not really tested) on x86 linux (Ubuntu), BeagleBoard, OMAP Zoom2 and Openmoko Freerunner :)

HERMITs: Detecting user activity

Wendy widget desktop running on OMAP Zoom2In our first demonstration introducing our Pervasive Widgets (the HERMITs), we just used the events on our SDL application (Wendy) to detect the user activity. However that is not very convenient if we want to use proper widgets in our devices, so we need to look for a more transparent way to detect user activity.

As we are running an X-server the XScreensaver extensions are a good option for that. What we want is to be able to detect when there is some user activity, but we do not want to get events every time user press a key or touch the screen... we want them only if that didn't happen for a while

Pervasive Widgets. Introducing the HERMITs

About HermitNow that the first decade of XXI century is about to finish, it is time to introduce a revolutionary concept to develop during the next one.

The Papermint Design team proudly introduces the HERMITs.

What is a Hermit?

truck or treat...

Hi everybody,

Halloween is the perfect excuse to do something cute.

We can't resist the monster sexappeal side and decide to do something. So we are having a party for kids on this month and a terrrific poster to announce.

If you want to use for your own scary party just download the full size image without the test from the image gallery (here)

Enjoy the sangría!


MUVIMAN a PhotoMint Deviation

MUVIMAN is a simple PhotoMint deviation. MUVIMAN extends the idea of real-time image sharing to real-time video sharing. Based on picoFlamingo this system allows to watch different real-time video streams and zoom into any of them.

MUVIMAN is aimed to support security guards on museums or offices allowing them to check in advance nearby video sources to increase their situation awareness.

We prepared a very simple concept demonstration and put it on a video.

PhotoMint First Tests

photoMintHi there,

Yesterday we announced our new project: PhotoMint. We think this is a nice project specially suited for our OMAP ZoomII and a interesting way to get us into the OMAP DSP world that we have not tried yet.

PhotoMint... Put an OMAP on your Digital Camera

PhotoMint is a new and revolutionary concept of personal digital camera. It is not about the camera itself, it is about how do you use your digital camera.
PhotoMint Mechanical ConceptPhotoMint Mechanical Concept

picoFlamingo "Cracking Egg". Clock Demo

One of the most interesting features in the new picoFlamingo ("The Cracking Egg") is the possibility to dynamically update slides. In order to illustrate this feature we had written this clock demonstration. It looks like this:

Cracking Egg Clock DemoCracking Egg Clock Demo

As you can imagine the digital clock in the middle of the screen will update every sec. The best thing is that this demo is almost trivial using the new UPDATE_TEXT command.

picoFlamingo Case Prototype


Our first try to put everything in a case. Still needs lot of work but it's a beginning. For a final version we will need to unsolder some connectors and build a small power supply to be able to use just one power source for everything

picoFlamingo case for Beagleboard 1picoFlamingo case for Beagleboard 1

And this is how it will look like with the picoDLP on top, before adding all the pico cabling. We also build a simpler case for our old B6.

picoFlamingo "Cracking Egg" Preview

Check this video showing the new main features included in the next picoFlamingo version, "The Cracking Egg". What you see on that video is a work in progress version and there is a lot of room for improvement.

Keep reading for the details...

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