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Comment Data sent to airlines (Score 5, Interesting) 217

The Travelocity guy avoided telling the whole story. They do provide relevant information, but if the government has the PNR with all the remarks in it, then it likely came from Travelocity or Sabre.

Travel agencies and 3rd-party web sites, such as Travelocity. put all this encoded stuff into the remarks section of the PNR, it's all that "H-" stuff. When the PNR is sent to the airline, NONE of the remarks are transmitted. The airline doesn't receive your IP address, for example. Seat numbers, phone and contact information are transmitted in Special Service Request (SSR) and/or Other Service Information (OSI) fields. One major exception is that Travelocity and AA share the same PNR when booking AA.

Now, the airlines have to send a whole bunch of data about you to the TSA to get clearance for you to board. Look up Secure Flight / APIS / AQQ and you can learn a little bit about it.

A.

Comment Re:How did they launch from the moon? (Score 1) 211

I've never understood how they were able to launch from the moon back towards Earth. Launching from the Earth requires massive infrastructure and huge rockets. Yes, the moon's gravity well is shallower, but still significant.

It's because the fundamental equation that relates a rocket's performance and the mass fuel it requires to orbital velocities is exponential. This makes it work out so that any chemical rocket leaving earth has to have the vast majority of its weight as fuel, where as a rocket leaving the moon only about half of its weight as fuel.

What's more, the entire lunar module and its fuel supply is dead weight as far as the earth launch is concerned, which makes the earth rocket and its fuel multiple all the bigger. Then there's the issue of bringing along enough fuel to slow down the craft into lunar orbit, and escaping lunar orbit back to earth. The lunar lander didn't need to handle any of that, either.

Comment Re:complex application example (Score 1) 161

Could you put multiple network cards on your scheduler machine, put the workers on different subnets and randomly dole out the jobs between those subnets? Seems like you'd be less likely to drop UDP packets that way, I'm pretty sure I ran across a utility (lsipc or something) that would list IPC resources, including shared memory. I seem to recall that the segments also show up in /proc somewhere. It's been a while since I've looked at it.

Not being able to ack important message packets seems like a design flaw.

Even though we have a LOT more hardware now than we did back in the day, you still can't BFI your way through a lot of the big data applications that companies are starting to try to get into. In the past, the company would just throw more hardware at a poorly designed application and that would "solve" the problem. I once saw a team throw 48 gigabytes of RAM at a leaky Java program, and schedule weekly restarts for the goddamn thing. But it's a lot easier to hit hard walls with big data, to the point where you absolutely can't throw more hardware at the problem.

Comment Re:Your Results Will Vary (Score 2) 241

I took nothing past Calculus either and up until two or three years ago never even used trigonometry in my professional programming. The last few years I've been writing satellite simulations, which has forced me to knock the rust off some of my old math skills. Most programmers can get away with very little math a lot of the time. A lot of very interesting programming involves a fair bit of math. That programming is generally being done by some guy with a Ph.D. in another field, and he's usually doing it in Fortran.

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