Thursday, March 1, 2018

Un-shortening URLs

URL shortening services such as are very popular, but sometimes they can be dangerous. This is why I am glad to see that a url un-shortening service is now available.

The way url shorteners work is that I can set up as a short url for and then you can save yourself some typing by typing into your address bar and be brought directly to . In this case the number of keystrokes is hardly worth the effort, but in many cases URLs can be very long and hence difficult to type in correctly.

The danger of short URLs is that you don't know where they are going to bring you to. For example you might be expecting to be brought to but instead find yourself brought to

The way works is that you go there and type in your short URL and it tells you where you will be redirected to if you use that short URL (this might involve multiple redirects). You can then decide whether or not you feel safe to visit the site in question.

Thursday, January 11, 2018

My new GlowOrb tells me when rain is imminent

I recently acquired a new gadget called a GlowOrb. This is an orb the size of a ping-pong ball which is MQTT enabled which means that it can be programmed to change colour to give an ambient indication of some metric you would like to be aware of. Previous owners have used their GlowOrbs for a wide variety of uses e.g. alerting on air quality changes. However, I am obsessed with rain (as are almost all Irish people) so I decided to configure my GlowOrb to alert me of the chances of rain in the immediate future.

I followed the colour scheme from official weather warnings. So if my GlowOrb is
  • Green (as in the picture) it means that there is < 20% chance that it will rain in the next 4 hours and I can cycle to work with confidence that I won't be like a drowned rat when I get there.
  • Yellow tells me that the chance of rain is between 20% and 40% so bringing a jacket might be a good precaution
  • Orange indicates that the probability has grown to 40% - 60%
  • Red implies that the chance of rain is over  60% so there is no point in putting out the washing.
The way it works is that each GlowOrb has a serial number (printed on the underside of the unit) and you send a MQTT message containing a colour code to a MQTT channel associate with the serial number to change the colour of your orb. Don't worry if you don't understand what this means, there is a web address like printed on the base of the unit (where XXXX-YYYY is the serial number of your unit) and if you visit this web address you will be given detailed instructions on how to use the GlowOrb. It also gives you a piece of JSON that you can import into any NodeRed service to have a working control program for your GlowOrb.

All I had to do to customise my GlowOrb was to write a simple NodeRed flow which accesses the BlueMix weather service every 15 minutes to determine the likelihood of rain where I live and then change the colour of the GlowOrb to match.

If you can imagine a use for your own GlowOrb, I encourage you to get one and experiment. They are quite cheap, but there is no formal ordering or pricing process for GlowOrbs. However, if you send a twitter message to @AndySc, he will give you a price quote in bitcoin or pound sterling.