Rantings of a Road Warrior

The real Beer-Lambert Law

From http://students.info.uaic.ro/~andrei.luca/blog/

Some­thing dif­fer­ent hap­pened to me on Friday.

Hav­ing just arrived at home from work, I was still sit­ting in the car, wait­ing for the song on the radio to fin­ish and to make good use of the time I was col­lect­ing the park­ing receipts and other bits of paper scat­tered around the car.

As I was ready to leave and switch the engine off, I looked in the rear view mir­ror to find one police car directly behind me. Look­ing up I was sur­prised to find another police car directly in front. Keep in mind I am parked at this stage.

“They must be here for me”, I thought to myself.

2 police offi­cers got out of the car behind me and approached me, in the mean­time I can see at least 3 police cars fran­ti­cally roam­ing the area.

“Hi, can we have a word with you please” said the first officer.

“There is a 2 year old child that was reported miss­ing, we have reports that she was seen in a black mondeo”

No bonus points for guess­ing which car I was dri­ving at the time.

My heart sank, “Oh dear”, I uttered.

“Can you step out of the car please, so we can ask you some questions”

The ques­tion­ing started

“Why are you here”

“Where are you com­ing from”

“What is your name, Date of Birth and your place of birth”

“Can you open the boot please”

“We’re going back to the car to check you on the com­puter, stay here”

In the mean­time, other police cars were still roam­ing the area, one of them stopped to say the child was found at a neighbour’s house.

It seemed the 2 police­men were wait­ing for con­fir­ma­tion over the radio before they send me on my way, once they got that one of them approached me.

“I sup­pose you heard that, thank you for your time, we have to be careful”

Still in shock, I thanked him.

The strange thing is dur­ing the whole con­ver­sa­tion I was think­ing, I’ve just been in town, I have a park­ing receipt, I must be on CCTV in and out of the NCP Park­ing, I paid using a credit card,  effec­tively I was think­ing of con­firm­ing my alibi.

All in all, happy end­ing. One thing about the Loth­ian and Bor­ders Police, they seemed to have responded very very quickly to the report, cov­ered the area and remained polite even with the adren­a­lin pump­ing in the rush to find the miss­ing child quickly.

“Going to Star­bucks for cof­fee is like going to prison for sex. You know you’re going to get it, but it’s going to be rough”

- Adam Hills

I’ve just received great news, I have passed my Prince 2 Prac­ti­tioner course. I am now a

Cer­ti­fied Prince 2 (2009 Edi­tion) Voodoo Specialist!

Woot!

I am going to start using Euronews no com­ment style posts here

Here is the first one

(From a friend of mine in Belgium)

“Yes, she was driving”

As I am tidy­ing up my home direc­tory, I found this old gem that I saved to keep me amused on a rainy day, the blog is as good place to pub­lish it as any.

——-

Subject: The case of the 500-mile email.

Date: Tue, 26 Nov 2002 14:57:40 -0800
From: Trey Harris <trey.sage.org>
To: 0xdeadbeef@petting-zoo.net

Here's a problem that *sounded* impossible...  I almost regret posting
the story to a wide audience, because it makes a great tale over
drinks at a conference.   The story is slightly altered in order to
protect the guilty, elide over irrelevant and boring details, and
generally make the whole thing more entertaining.

I was working in a job running the campus email system some years ago
when I got a call from the chairman of the statistics department.

"We're having a problem sending email out of the department."

"What's the problem?" I asked.

"We can't send mail more than 500 miles," the chairman explained.

I choked on my latte.  "Come again?"

"We can't send mail farther than 500 miles from here," he repeated.
"A little bit more, actually.  Call it 520 miles.  But no farther."

"Um... Email really doesn't work that way, generally," I said, trying
to keep panic out of my voice.  One doesn't display panic when
speaking to a department chairman, even of a relatively impoverished
department like statistics.  "What makes you think you can't send mail
more than 500 miles?"

"It's not what I *think*," the chairman replied testily.  "You see,
when we first noticed this happening, a few days ago--"

"You waited a few DAYS?" I interrupted, a tremor tinging my voice.
"And you couldn't send email this whole time?"

"We could send email.  Just not more than--"

"--500 miles, yes," I finished for him, "I got that.  But why didn't
you call earlier?"

"Well, we hadn't collected enough data to be sure of what was going on
until just now."  Right.  This is the chairman of
*statistics*. "Anyway, I asked one of the geostatisticians to look
into it--"

"Geostatisticians..."

"--yes, and she's produced a map showing the radius within which we
can send email to be slightly more than 500 miles.  There are a number
of destinations within that radius that we can't reach, either, or
reach sporadically, but we can never email farther than this radius."

"I see," I said, and put my head in my hands.  "When did this start?
A few days ago, you said, but did anything change in your systems at
that time?"

"Well, the consultant came in and patched our server and rebooted it.
But I called him, and he said he didn't touch the mail system."

"Okay, let me take a look, and I'll call you back," I said, scarcely
believing that I was playing along.  It wasn't April Fool's Day.  I
tried to remember if someone owed me a practical joke.

I logged into their department's server, and sent a few test mails.
This was in the Research Triangle of North Carolina, and a test mail
to my own account was delivered without a hitch.  Ditto for one sent
to Richmond, and Atlanta, and Washington.  Another to Princeton (400
miles) worked.

But then I tried to send an email to Memphis (600 miles).  It failed.
Boston, failed.  Detroit, failed.  I got out my address book and
started trying to narrow this down.  New York (420 miles) worked, but
Providence (580 miles) failed.

I was beginning to wonder if I had lost my sanity.  I tried emailing a
friend who lived in North Carolina, but whose ISP was in Seattle.
Thankfully, it failed.  If the problem had had to do with the
geography of the human recipient and not his mail server, I think I
would have broken down in tears.

Having established that -- unbelievably -- the problem as reported was
true, and repeatable, I took a look at the sendmail.cf file.  It
looked fairly normal.  In fact, it looked familiar.

I diffed it against the sendmail.cf in my home directory.  It hadn't
been altered -- it was a sendmail.cf I had written.  And I was fairly
certain I hadn't enabled the "FAIL_MAIL_OVER_500_MILES" option.  At a
loss, I telnetted into the SMTP port.  The server happily responded
with a SunOS sendmail banner.

Wait a minute... a SunOS sendmail banner?  At the time, Sun was still
shipping Sendmail 5 with its operating system, even though Sendmail 8
was fairly mature.  Being a good system administrator, I had
standardized on Sendmail 8.  And also being a good system
administrator, I had written a sendmail.cf that used the nice long
self-documenting option and variable names available in Sendmail 8
rather than the cryptic punctuation-mark codes that had been used in
Sendmail 5.

The pieces fell into place, all at once, and I again choked on the
dregs of my now-cold latte.  When the consultant had "patched the
server," he had apparently upgraded the version of SunOS, and in so
doing *downgraded* Sendmail.  The upgrade helpfully left the
sendmail.cf alone, even though it was now the wrong version.

It so happens that Sendmail 5 -- at least, the version that Sun
shipped, which had some tweaks -- could deal with the Sendmail 8
sendmail.cf, as most of the rules had at that point remained
unaltered.  But the new long configuration options -- those it saw as
junk, and skipped.  And the sendmail binary had no defaults compiled
in for most of these, so, finding no suitable settings in the
sendmail.cf file, they were set to zero.

One of the settings that was set to zero was the timeout to connect to
the remote SMTP server.  Some experimentation established that on this
particular machine with its typical load, a zero timeout would abort a
connect call in slightly over three milliseconds.

An odd feature of our campus network at the time was that it was 100%
switched.  An outgoing packet wouldn't incur a router delay until
hitting the POP and reaching a router on the far side.  So time to
connect to a lightly-loaded remote host on a nearby network would
actually largely be governed by the speed of light distance to the
destination rather than by incidental router delays.

Feeling slightly giddy, I typed into my shell:

$ units
1311 units, 63 prefixes

You have: 3 millilightseconds
You want: miles
        * 558.84719
        / 0.0017893979

"500 miles, or a little bit more."

Trey Harris

So, UNIX, love it or hate it has been around for a while.

It’s now 40 years old, it makes you won­der if com­put­ing is really that fast mov­ing. I believe that the fun­da­men­tals remain the same. Tech­niques, ideas and  usabil­ity (hope­fully) improves with time, as more and more users use it and devel­op­ers con­tribute to it.

It’s a never end­ing circle.

This also reminds me of the old say­ing which goes “Old soft­ware never dies” I’ve met some peo­ple who I have writ­ten a small piece of soft­ware for them while I was at school, I found out that they were still using it 8 years later!

For those who want to read more, a BBC arti­cle for you

As demon­strated on youtube.

I’ve always thought of our police as being soft on crim­i­nals, I also won­dered if they’d use harsher and more bru­tal force to catch the crim­i­nals if the crim­i­nals would stop running.

This has answered my question.

This is cool!

From: Your daily gif blog : Bul­let hit­ting wall.

I’ve passed my Prince2 Foun­da­tion exam. Wasn’t easy, but I got there in the end.

I only have the Prac­ti­tioner exam to go now, it’s on Fri­day and I am not 100% ready for it