Getting a Ubisense CellData schema

I posted this on the Ubisense forum...I'm running into many quandries about getting at different parts of the Ubisense architecture. I'm trying to build a service to age out Ubisense tags. The issue is that Ubisense 'remembers' the last sensed location of a tag. This makes sense when the tag is on a pallet in a warehouse, but causes a problem detecting when Elvis has left the building, in other words, when a person walks out of range of the sensors, he's still 'in the building'. This can cause issues depending on the application.

I am working on code based on this forum exchange..., and it seems to be working, though I'm getting sporadic exceptions:


System.NullReferenceException was unhandled
Message="Object reference not set to an instance of an object."
Source="UbisensePlatform"
StackTrace:
at UPrivate.au.a(Byte[] A_0, EndPoint& A_1)
at UPrivate.am.j()
at UPrivate.am.k()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()


I think this might be for some underlying thread collision, or a subtle bug in my own code, so I'm trying to add additional instrumentation to my code. The current code is using the multiCell and RemoveObjectLocation. I am still working to debug that, but at the same time, I'm looking at addressing the CellData schema directly, using the remove_object method. I want to see if this clears up the problem.

I'm also doing burn-in testing of the code, right now there's a robot running around the Social Computing Room carrying around a few Ubisense tags to drive the system...quite fun!

Sun Worldwide Education and Research Conference

Here's an item that I'll probably check on this week...

Sun is moving fast on many fronts in 3D worlds - but
focusing on education. I hear they will have an
important announcement this week at their Worldwide
Education & Research Conference in SF:
http://www.events-at-sun.com/wwerc08/agenda.html

The agenda shows SUN Founder Scott McNealy speaking
wedged between the Immersive Education Forum and Lunch
the second day. I'm GUESSING that this placement is
intentional and hints that Sun has BIG news for
educators interested in immersive environments.

I played a bit with MPK20 (the Sun virtual environment).  It still has limited features, but it's open, and among the ones to watch, along with Croquet.  I may put up the feed in the Social Computing Room as availability permits, if anyone is interested in viewing it there, let me know.

Other than that, I'm wrestling a bit with UbiSense again! 

Back to better habits

I've neglected the blog, but trying to do better.

It has been a busy few months, largely spent putting together talks and demonstrations of the Social Computing Room, as well as the other spaces in the RENCI UNC Chapel Hill Engagement Center.

I'm into a lot of different things right now, which I'll describe in greater detail later. I'm:

• Working more with UbiSense, which is a real-time 3D location sensing system. I've been concerned with bridging UbiSense using their .Net API to something called VRPN, which is an abstraction layer developed in the Computer Science department at UNC Chapel Hill. Eventually, we'll have a full-blown UbiSense server implementation. I'm working on handling button press signals from the tags right now, having some C# fits.
• I began working on a tag ageing service for UbiSense, and ran into some code on the UbiSense forum that got me started (the UbiSense forum has been very helpful).
• I've been learning OpenGL and GLUT, which I'll need as we develop new applications for the Social Computing Room.
• Between VRPN and OpenGL, I'm having to use C++, which I've dabbled with in the past. It's not been my language of choice in the past, but it's becoming more useful.

Geez, that's enough for now.

Rails to the rescue

It's good to keep the tools in your box sharp, I'm happy I've been messing with Rails on my own, because I need to knock out a prototype for work really quickly, Rails to the rescue!

A couple notes, NetBeans 6.0 is out, and I highly recommend it as your Rails development environment. I took a few minutes to switch to the new IDE, and it's very smooth. Alas, when I switched, I was having a very hard time getting plug-ins, and getting Rails to upgrade via Gems. I was receiving weird buffer errors. Google to the rescue, there was a simple fix that involved upgrading gems..just run this command:

gem update --system

and you should be in business...thanks to the DRY blog for the heads up! I'm also incorporating the WillPaginate plug-in in this round, and I've got to mash-up with Google maps. I did find a gem for Google maps, we'll see how far I get, but I'll post any findings..


Updates:

Apparently, will_paginate returns nil if your collection is smaller than the per-page. I was having a problem where I was returning an array of results for my 'position log', and it would not show up in the form where I had used

<%=will_paginate @obs_log %>

I'm not sure why, but here's the code for will_paginate..

# Renders Digg-style pagination. (We know you wanna!)
# Returns nil if there is only one page in total (can't paginate that).
#

def will_paginate(entries = @entries, options = {})
#total_pages =

if entries.page_count > 1
renderer = WillPaginate::LinkRenderer.new entries, options, self
links = renderer.items

content_tag :div, links, renderer.html_options
end
end

So this really does me no good, I'm sure I'm missing something obvious, but it should at least render the collection without the paging cruft. I'm just in too much of a hurry, but this was frustrating. I punted and just showed the last 30 or so with a :limit in my find_all.

I want to present a REST-ful interface for my app to accept data from a mobile with a GPS, I ran across this RailsCast on REST, which seems useful...

will paginate

I've been working on a Rails app as a sort of hobby, it's for a site that I'm prototyping for fun, and we'll see where it goes. I've been off and on, depending on the home schedule, but having a concrete goal helps in my effort to keep my chops up. My areas of focus right now are Ruby, Rails, AJAX, JavaScript (with the Dojo toolkit), as well as CSS and design (never my strong suit). The things I work on lately are quite fun and challenging, but have taken me away from heads-down web app coding for quite a while.

Anyhow, working with the project, pagination turns out to be deprecated in Rails. I grabbed the new plug-in, classic_pagination, but the first thing I got is a notice that it's dead code, and I should move to WillPaginate. I love working with Rails, but the capricious nature of open source does have its drawbacks! Anyhow, I'm working with it, it looks nice. I found a quick jump-start on a RailsCast episode dedicated to pagination, linked here. RailsCast is a fine resource, and I highly recommend it.

One thing I would point out, and something that I'm still working to change, is to wake up to the fact that Rails and Ruby let you pop open a console and work with your code while you code. Try things out, see what responses you get, and if it looks good, copy it into your codebase. As a Java monkey, this is still a foreign mode of operation. The point is, if you're used to coding Java like I am, get used to having that console open, and monkey with your code! Check out the RailsCast, and give WillPaginate a try.

Taking the Social Web into the virtual world

Here's an interesting article on IBM's efforts to blend social software, identity, and the virtual world through Lotus.

IBM Lotus programmers and engineers from IBM's research groups are currently working on ways to employ virtual reality technologies with Lotus Connections social computing software, said Jeff Schick, vice president of social computing for IBM.

I heard someone describe the 3D web by saying 'people are back', and I think this is the true strength of environments like Second Life. It's not about the graphics or a particular virtual space, it's about the people and experiences that are available. Maintaining and monitoring a social network is Web2.0, the 3D web is about being present with friends and peers in meaningful ways, through virtual experiences.

Building the 'web of things' means breaking some eggs

I've been writing a lot about the 3D web lately, and I'm still pretty jazzed about what I've seen. Part of the appeal is the way that environments like Second Life serve as a metaphor for the merging of the physical and virtual worlds that is taking place all around us.

Anyhow, way back in the day, I was writing here about the next web, or Web3.0, or whatever you want to call it. Back in those old days, about 12 months ago, I was really thinking more about the new web, and the mobile web, like in this dusty old post. Someone had already fronted Mobile2.0 as a variant of Web3.0, in the confusing cloud of infotech talking heads.

Anyhow, one barrier to 'Mobile2.0' is the fact that networks and devices can't be ubiquitous if you can't get your cell phone to run an app or use the network you want, witness the entire iPhone hacking phenomenon. The subtext of the whole Google Android platform seems to be an attempt to smash through the walled gardens that are your typical telecom, witness the mission of the Open Handset Alliance. Anyhow, the actions of Google, and the recent announcement by Verizon that they are going to open their platform to any app and any service hint at the cracks that are appearing in the walled gardens. Does this hint at a new wave of innovation driven by the availability of an open platform? I'd think so, but at any rate, changes in the mobile space are coming, and they'll contribute to the next 'version' of the web!