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Showing posts from 2015

Your software sucks (any data you give it)

At 1524h, On the afternoon of January 15th 2009, US Airways Flight 1549 was cleared for takeoff from Runway 4 at New York's La Guardia airport. The airplane carried 150 passengers and 5 flight crew, on a flight to Charlotte Douglas, North Carolina. The Airbus A320's twin CFM56 engines had been serviced just over a month prior to the flight. The plane climbed to a height of 859m (2818 feet) before disaster struck. Passengers reported hearing several loud bangs and then flames being visible from the engines' exhaust. Shortly thereafter the 2 engines shut-down, robbing the Airbus of thrust and its primary source of electrical power. At this point the Captain took over from the First officer and between them they spent the next 3 minutes both looking for somewhere to land, while also desperately trying to restart their aircraft's engines. What Happened? A flock of birds had crossed the path of the Airbus and several had struck the plane. Both engines had ingested bi

Even the errors are broken!

An amused but slightly exasperated developer once turned to me and said "I not only have to get all the features correct, I have to get the errors correct too!". He was referring to the need to implement graceful and useful failure behaviour for his application. Rather than present the customer or user with an error message or stack trace - give them a route to succeed in their goal. E.g. Find the product they seek or even buy it. Bing Suggestions demonstrates ungraceful failure. Graceful failure can take several forms, take a look at this Bing [search] Suggestions bug in Internet Explorer 11. As you can see, the user is presented with a useful feature, most of the time. But should they paste a long URL into the location bar - They get hit with an error message. There are multiple issues here. What else is allowing this to happen to the user? The user is presented with an error message - Why? What could the user possibly do with it? Bing Suggestions does not

Counting Images, a FireFox Add-on

Many of my clients ask me to test their content management and processing systems. Often this involves investigating how the software handles images of various sizes as well as text of various lengths or types . To help create test-images, I created this little FireFox Add-on . The Counting Images add-on starts with one click and can be used to create an image of a custom size. For example: if you need a 300x250 MPU advert image - just enter 300 and 250 into the panel and click Create Image . To download the image, just click on it - as you would a a link and choose Save. The image files are named width x height .png , and include markings to help identify if they have been truncated e.g.: The marked numbers refer to the size in pixels of the rectangle they are in. E.g.: the blue rectangle (always the outermost one) is 150x100 pixels in size. Another example: As you can see the rectangles start at the defined size and count down in steps of 20 pixels. What could

Learning from the Boeing 787's broken software.

Earlier this year Boeing 787 maintenance engineers were given some new instructions by the FAA (The US government's: Federal Aviation Authority). They were informed that if the airplane's electrical generators were left running for 248 days, they would enter the fail-safe mode.  In plain English: they will stop producing electrical power. This short video looks into why that might be and how this information can help us to test our software. The FAA directive is available on their website . A Guardian article: Boeing 787 bug could cause 'loss of control' on Dreamliner