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Microblogging: Thinking out of the Twitter

anil — Thu, 19 Jan 2012 13:04:53 +0000

As the Internet infrastructure evolved over recent years, services running on it become more visible and tangible to the world. Internet as an infrastructure is less talked about these days. Rather, services running on them are counted with more reverence. We are thinking about building further upon those services and forget the Internet as the fundamental infrastructure and fail to see its virtues.

Twitter started as a small microblogging service, built on top of the Internet, has grown into an infrastructure over a few years. Now there are numerous business-critical (if not mission-critical) services built on top of Twitter. Twitter is a service built, owned and operated by a single entity. The whole of the Internet depend on Twitter for microblogging. If email service followed the Twitter way, we would have had only one Hotmail or Gmail and remained as a single point of failure.

Think of microblogging service as a decentralized infrastructure; like email or instant messaging. Email infrastructure can be set up by anyone yet can exchange emails with any other email server (its users) in the Internet. So does IM (with inter-domain federation). Why not the same with microblogging and liberate it from its current bulletin board architecture?

Microblogging URI can also take the form of email address similar to how instant messaging with federation works. For example, Google could set up a microblogging service for its own use and microblogging feeds of Larry Page could be possibly available at larry@google.com and corporate feeds could be available at wire@google.com. Client software like TweetDeck can fetch feeds from respective servers. Any one can subscribe, route, federate feeds from any any microblogging server. In that situation, microblogging is not dependent of any single provider and so there is no single point of failure. It will work just like the email system.

There can be a feed management layer like what Feedburner does to RSS/Atom feeds. In fact Twitter is best qualified to provide this layer now.

This will make microblogging totally decentralized. This architecture is a very natural one for an Internet service. Above all this will take away the responsibility of running the microblogging service for the whole of Internet from any single entity.

New Indian Rupee Symbol (and the Problems with the Design)

anil — Wed, 25 Aug 2010 19:37:00 +0000

India gets new currency symbol. Whole of India is excited about it and so am I. Now waiting for type face designers to include the symbol in my favorite fonts.

Government of India approved a currency symbol design contest last year. And the year-long competition came to an end and the winner is an IIT’ian. He designed a symbol which is described as “combination of the Devanagiri letter ‘Ra’ and the Roman letter ‘R’”; both first letter of the Indian currency name “Rupee”.

Indian Rupee Symbol (curtsey Wikipedia)

Many people around the world still think that India, along with the neighboring countries such as Pakistan, Sri Lanka and Bangladesh share the same currency. So this move is going to make Indian Rupee distinctive. Media welcomed the symbol as it shows off the strength of the up coming currency.

But I see some problems with its design!

Have you tried using this symbol? Not yet? Pick a pen and try it yourself right now before you read further.

Well, how does it look? Just look at your best attempt. And now try writing Dollar, Pound Sterling and Euro symbols and see. I don’t expect you to be a freehand drawing expert; but as a common man, what do you think? Can you see a difference? What’s the problem?

Besides proportion requirements, this symbol needs those “calligraphy edges” for that finished look. Its elegance depends a lot on those beveled edges and that is quite unfortunate. To create those edges, you need thick lines. That is the problem here: this symbol won’t look as good in thin lines line (i.e. while writing with regular pen or in regular font set)! This symbol needs to be bold face–always.

Compare this with other currency symbols we know. What is it missing? Here is my list:

A good shape that is tolerant to imperfection while writing.
A good shape that would look good irrespective of the thickness of the line it is drawn with.
A good shape that has a fairly good degree of symmetry. A symmetric symbol has lot of flexibility and possibilities while designing type faces. And easy to draw too.

The symbol started appearing in news papers and other print media already. People try experimenting with it now in headlines and advertisements where they can use a bold type face. Now my mind is getting conditioned to it though I am yet to see it in body texts.

I wish someone could come up with a one-pixel version of the symbol so that it can used in body texts. Also a variant for writing by hand.

Hobby Flying (in India)

anil — Tue, 08 Dec 2009 18:32:26 +0000

Ever since I saw a trainer aircraft flying at Sankhumukham during my childhood I fancied myself flying aircrafts; not as a career but as a hobby. I never got a chance to make an attempt due to lack of opportunity. The main problem was the commitment one needs to take to put the hands on. The money involved is significant and time demanded is impractical for a working person.

My pursuit was mostly limited to collecting training materials and articles and discussions with a few friends who share same interest until I ran across Mysore Aerosports (and then Bangalore Aerosports, Bangalore).

I found them on the web and came to know about an amazing programme they offer called Trial Instructional Flight on an X-Air Microlight. This programme allows to fly an aircraft in a short in-the-air training session of one hour. There is no commitments. No need to enroll for student pilot license. No nothing.

A few things about Microlight aircrafts: Microlight Aircrafts (or simply microlights or ultralights) are two-seater aircrafts with less than 450Kg of gross weight and a maximum level speed of less than 220Kmph. To start flying and for hobby flying microlight aircraft is a better alternative to conventional trainer aircrafts (such as single-engine Cessna). A microlight is more basic (and less complex) in construction, for flying and maintenance but, at the same time, as safe as any other comparable single engine-aircrafts. All these at a much lower cost–cheaper to own, maintain and operate. Microlights are more sensitive and demand more pilot inputs. This is not an aircraft for those who want to put their aircraft in autopilot and relax.

***

Me and my friend Raj decided to try this out at the next immediate weekend convenient to both of us. So we called up Bangalore Aerosports and got our slot reserved on 31st October at 7:30 early morning.
—

It is simple as a safety pin! Minimal controls and weighs around 250kg only. It must be fun to ride (if you master it).

—

Bangalore Aerosports operates from the Jakkur Aerodrom, Bangalore. There is a small runway and took my first flight with Wg. Cmdr. Ashok Mehta. He explained me the basics before the flight.

Flying in a microlight is way far different from flying in a regular passenger aircraft (like A320) in which you are not exposed to any realities of the medium of air. Also the massive structure of passenger aircrafts easily take turbulence of the air and we seldom notice the severity. But in the case of a microlight, it is of the size of an auto riksha! A small inconsistency in the air would result in vigorous shakes and it is real scary for the first timer. But, normally, one would get accustomed with that in a few minutes.

It was interesting to learn that the air (or the atmosphere to be more precise) has more dynamics than we notice that seldom affect our lives on the ground but have significant influence on flying objects. There is a lot to learn and get acquainted to to become a good pilot besides learning to control an aircraft.

We really enjoyed this flying though I am not sure whether I would go all the way and obtain a PPL(M) myself. But surely I will be back there soon for more flying.
—

Ultralight aviation: http://en.wikipedia.org/wiki/Ultralight_aviation
Bangalore Aerosports: http://www.bangaloreaerosports.com/
Jakkur Airfield: http://en.wikipedia.org/wiki/Jakkur_Airfield

Netcat (nc): “TCP/IP Swiss Army Knife”

anil — Tue, 26 May 2009 06:31:28 +0000

Many of us use telnet as a network debugging tool quite often. Just with its hostname and port options we find it very useful. But, I’m sure that many would recall following situations where we find the telnet client inadequate:

To test a UDP service
Want to send a pre-prepared set of request/responses to a server (to test a service)
Specify a Gateway for the TCP or UDP connection (checking routing and firewalling)
Receive and store dump of the traffic (network and application troubleshooting)
Send a UDP broadcast over the subnet (Network and application testing)
To set the ToS (type of service) flag in IP packet (to test QoS settings)
To copy a file over network without any regular services running
Do a port scan (without opening I/O)
Mimic the request/response sequence of a service/client you want to test

There is a less-known tool called nc–acronym for Netcat–which was ranked 4th in the latest Top 100 Network Security Tools 2006 conducted by Insecure.org and always in the top 5 in previous years as well.

nc can perform all the above and more. As it is rightly assigned with the caption of “TCP/IP swiss army knife.” Here is a quick set of commands to use nc for the use of a network administrator/troubleshooter.

Please note that Linux and BSD ports of nc differs in behaviour and syntax. This post is mostly based on the Linux port. I have tried to mention the difference where ever possible.

Test a TCP Service:
nc
e.g.: nc www.google.com 80

If you need to run a shell command after the TCP connection is established, use the “-c” option.

nc -c wwwclient www.google.com 80

There is an important behaviour you need to notice while using -c and -e (invokes a script) options: the called command is supposed to handle both input and output of nc. This means that while passing an echo command, for example, with -c option, you cannot expect nc to print the response to standard out. For example, the following command writes nothing to standard out:

nc -c “echo GET / HTTP/1.0″ www.google.com 80

This is because nc pipes the HTTP response from www.google.com to echo. The -e option has the same behaviour. In the BSD port of nc there is no -c option available. And the -e has a very different meaning.

If you want to make a request to a server in two or more lines (as in the case of, say, HTTP protocol), write them down in a file and cat-pipe that file to NC. For example if you want to find the public IP address of your Internet gateway, create a text file http.txt with the following content:
GET /ip HTTP/1.0 Host: www.linuxense.com

Now issue this command:

cat http.txt|nc www.linuxense.com 80

In certain protocols, such as SMTP, it needs to wait for the server to make a response before nc sends the next request. In such situation the -i option comes handy; it waits for the specified number of seconds before it sends the next line.

Now try this SMTP transaction. Save the following in to a file named, say, smtp.txt
helo greetings mail from: rcpt to: data Subject: test from Netcat
Hello, This is a test from Netcat See ya! ~me .

Now play out this transaction:

cat smtp.txt | nc -i 2 your_smtp_server 25

See the -i in action.

There is a -n option that disables any DNS look up. This is useful if you are providing the IP address of the host and to explicitly say so to nc.

Use -p option to specify a source port. It is even possible to specify a range of port as in 80-1024 (both inclusive). If you omit the -p option, it will use a random port.
Emulate TCP Service
Use the -l flag to instruct nc to stay in listen mode. Use the following to bind nc to port 8000:

nc -l 8000

Normally nc quits when the remote connection closes. To make it stay listening for another connection, use -k (found to work only in BSD port).

Here -p option to specify the port it is listening to is allowed in Linux. In the BSD port, this is illegal.
Emulate a UDP Service
Use the -u option, nc will turn the protocol to UDP. Almost all options which are valid for TCP mode (default mode) are valid with this option too.

Emulate a DNS service:

nc -u -l -p 53 (note that all parameters are similar to those in TCP mode. The option -u makes all the difference).

Here, the -p is a required option in Linux where us in BSD it is not permitted.

Now, run a dig command at it:

dig @localhost www.linuxense.com

You will see a partially readable line being printed on the console and this is how a DNS query looks like. Capture this into a file:

nc -u -i -p 53 > dns-query.txt

And playback it at a functional DNS server and see the output:

cat dns-query.txt |nc -u mydnsserver 53
Specifying Source IP Address:

If you are on your gateway and you want to specify the source IP address of packets leaving the gateway, use the -s option. For example:

nc -s 192.168.1.1 remotehost 80
Run a Zero I/O Port Scan
See this example:
nc -z -v remotehost 80
The -z runs nc in zero I/O scan mode. -v option is to turn on the verbose mode. It is also possible to specify a range of IP addresses as follows (both IP addresses are inclusive): nc -zv remotehost 80-1024


Set "Type of Service" (ToS) Flag
The flag -x  allows to set the IP ToS flag. Possible values are "Minimize-Delay", "Maximize-Throughput", Maximize-Reliability", "Minimize-Cost".

Set Up a Service Gateway/Proxy
This is a quick and trivial service gateway you can try out in a few seconds. You device more sophisticated gateways with nc. BSD port of nc provides built-in support for this functionality with -X and connect verb.


If you enjoy reading this post and liked nc, please post here the nc tricks and hacks you invent.
--

Related post:

Learn IP Networking
Further reading:

BSD nc man page

GNU Netcat official homepage



Billboards of Recession
anil — Sat, 17 Jan 2009 06:16:10 +0000
Kochi is a city of billboards. You can see them as soon as you enter the city from either side. Majority of those billboards are rented out by real estate biz (both big and small). The second position (way below the first one) is taken by jewellers. The third  is cell phone brands and the remaining miniscule percentage is shared by the rest. That used to be the billboards share distribution in the city. But this time when I visited Kochi (my first visit in this year), I noticed one things as soon as I entered the by-pass: Many billboards are empty!





Billboards of Recession


Collage of some photographs of empty billboards I took. Follow this link to my Picasa album to see them separately
I am not into media selling business and I know nothing about it; this caught my attention accidentally. But this interested me very much because this is a direct indication of the fact that advertisers stopped spending possibly due to budget cut. To me this looked as a direct measure of the recession our economy has been passing through. A friend of mine in the advertisement industry told me a few weeks ago that promotional budget is what businesses would cut doen when there is cash crunch. This point is substantiated by what I saw there.
Billboards must be cheaper now. Those who want to have their message displayed in the city and think that still it is a good time, this is the opportunity you have been waiting for. I am sure that other cities too have empty billboards reading “recession” on them.
Another interesting observation is that, at some key locations such as Marine Drive, small-time guys have already rented couple of prominent billboards. May be, people started taking advantage of the situation.



Valparai: SB Anniv Ride
anil — Mon, 29 Dec 2008 08:41:27 +0000
I don’t remember who exactly suggested Valparai as the anniversary ride destination of Silver Bullets for this year. The choice was not bad as it was a hill station (most of us like to ride up to a hill, then ride down and live the next one week with post-ride hangover). And that even makes some write ballads and poems.
Each ride influences the way we look at our lives as we see new faces and places. I particularly love going places on my motorcycle. It moves me over miles and towns and states over highways, county roads and even through woods while in touch with the nature. I feel closer to people and places than while travelling in a car. So each time I get a chance to get on my Bull for a long ride, it makes me happy.
Valparai is a hillstation in Coimbatore district of Tamil Nadu. It is a small township and is part of the Western Ghats. We decided to take NH 47 up to Angamali and then deviate to Athirapalli, Vazhachal, Anakkayam, Malakkappara Tea Estate and reach Valparai covering around 400 km. There were eleven members to ride this time (including Raj as a pillion and a another guest rider). Of which ten were from Trivandrum and our new member Bejy Mathew from Kochi.
I started by 4:20 in the morning. I had to pick Raj from home and I headed to Manacaud. He was ready and already started twitting (he was the “official” twitter and photographer of this ride). We were planned to meet with the rest of the group at Kazhakootam junction. We reached there by 5:50. The sky was so beautiful with fabulous moonlight (as the moon the day before was the largest full moon of the year). The gang arrived and we started off at 5:20.
There is nothing like enjoying day break on the saddle a motorcycle; that too in crispy weather. This time too, it was no exception. We regrouped at 7:00 at Kayamkulam. The next regroup point was before the Cherthala bypass and we reached there by 8:45. I gave a call to Bejy, our host at Ernakulam. We were supposed to meet Bejy after Aroor bridge. The first rider in the group found him by 9:15. Bejy’s home is in a nearby beautiful island called Kumbalam. We reached Bejy’s home and there we were greeted by Bejy’s parents and his lovely four-year old son, Aron. Bejy’s mom prepared very homely breakfast for us (thanks Aunty!). We ate enough and more of idly, appam, cake and other stuff. She was kind enough to prepare and serve hot appams on-the-fly.
Bejy’s planing was meticulous! He prepared four copies of riders’ list along with required details to be handed over at check posts (we usually end up spending lot of time at check posts as each rider fills in data in their registers). His Bullet was loaded with everything we would require in such a ride.
We refuelled at the IOC pump near Edapally and headed towards Angamali by 10:55. NH 47 was not that crowded as it used be. And the weather was sunny which added up our spirits and enthusiasm. We rode at around 70 kmph with occasional burst to 90-100. We reached Angamali at 11:25. Our next leg took us to Athirappilly. We passed Athirappilly by 4:05pm. We had a short stop there for a few snaps. The fall looked awesome from the

highway. Immediately after that we reached  Vazhachal . After Vazhachal the road was empty as it entered the forest and traffic was low–I hardly remember seeing any other vehicle on the road. So if you have plans to take this route, be prepared to handle a breakdown and have water and food to eat. There is nobody out there to offer you any of these.
That leg of the ride was not bad though the place was not scenic, the roads were mostly good but there were some bad segments as well. At around 5:00pm we entered a tea plantation area known as Malakkappara. We had tea at a rod-side tea shop. The people there were talking Funny Malayalam with Tamil accent. There were 20km ahead of us to reach Valparai. The roads were very twisty and narrow. At one particular downhill left-hander (a horribly designed one which appeared to go straight to a first-timer), I made a misjudgement and I narrowly escaped from falling down.
We reached Valparai and it was not difficult to spot the Hotel Green Hill Resort where we reserved our rooms. Bangalore gang led by Jayan SR reached around an hour later. I was meeting Jambo, Jawahar and Udhay for the first time. We had a great dinner party together and Jay (our club moderator) was presented with a memento, as a token of gratitude by the club members. Party went on well and entered with a philosophical discussion between Dr. Gopu and Jambo–I can see those who were present in there, while reading this,  laughing their heart out   
Valparai is a very small township with a strip of road with small shops and restaurants. I was told that the government do not entertain tourists there. There is not much choice for stay. Our hotel was not all that bad as a bikers’ stay and was bang-for-the-buck. The weather was cold but bearable.
We had a nice breakfast and packed our stuff and hit the road by 9:30 in the morning. As soon as I turned into the main road, I got a hitch hiking request from a police man! Folks, the real story begins now!
I love giving ride to local people. I get to give a ride to at least one person every trip. This time it was a police man. He jumped over the Bull and I started catching up with the rest of the gang. Until I passed a few curves, I was not sure how he would react if I leaned my bike a little bit more and enjoyed the roads. To my surprise I got  overwhelming response from him. He started saying some cheering up words in Tamil. So I started riding faster   That was fun of a lifetime–speeding with a police man! He started shouting to on coming vehicles to give way for us. For the rest on the road, it appeared that we were on an emergency. He wanted me to over take every vehicle in front of me. We were climbing the hill and got way ahead of the rest of the team in a few minutes time. We were negotiating curves at peg-scrapping speeds and he was enjoying all along. We negotiated a right hander and he made the sound “hum” which meant go faster. I took the immediate right turn at speeds above 50+ and before we could realise the bike flipped on its right side with both the riders. There was spilled diesel on the road! While falling I looked behind and saw Akhil too had his bike flipped and fast nearing me sliding on the road. Luckily we stood up and cleared the road. Thanks Akhil, if you didn’t stop (and fell down), probably you would have run over me.
The police man stood up and started praising God for such a safe fall. He appreciated me for my riding skills and he said he enjoyed sitting behind me. He asked me to give him my address and phone number (I was afraid that I would receive a summons for speeding but I haven’t received anything as of this writing   ). There came a shuttle bus and he continued his journey in that.
There were some minor problems with the bike and me and Ahil had some small bruises here and there. Jayan’s first aid box came handy and Dr. Gopu convinced everyone that having a doc in the team is worth a million! Thanks Gopu for your valuable help.
This leg of the journey was more scenic than expected (see the links below). Roads were well paved and marked. The valley had a fantastic view from the top. Dams on the way looked fabulous. We spent a lot of time taking photos and roaming around.
Trivandrum and Bangalore team parted just before Pollachi. As the Banaglore team proceeded to Pollachi we took a left turn and hit NH 47 at Vadakkancheri. The traffic in NH was maddening till Chalakkudi and we zipped through after that till Vyttila, Ernakulam. Bejy said good bye there and left for his home. The sun went down as we passed Aroor and rain was kind of on and off after that till Alapuzha.
It was a very normal ride after that till Trivandrum. We had a regrouping at Kazhakootam. By that time the group led by Raghu and Bala reached homes ahead of us. I dropped Raj at home and reached home by 11:45pm. My Bull performed very well in this trip; thanks to Crank for tuning by bike. I guess it returned very good fuel average as well. 
Over all trip was fantastic and I am looking forward to the next one.
***
Links:
0. Silver Bullet’s Twitter feed.
1. Bangalore to Valparai by Udhay (Picasa)
2. Crank’s album (Picasa)
3. Jayan S.R.’s album (Picasa)
4. Raj’s album with 300+ snaps (Smugmug)



Best Reference Site for Each Programming Language
anil — Sun, 21 Sep 2008 18:37:28 +0000
Inspired from a Slashdot post, I thought of preparing a list of best reference web sites for each programming languages that we use at Linuxense. Send in if your suggestions.


 C

http://www.acm.uiuc.edu/webmonkeys/book/c_guide/


C++

http://www.research.att.com/~bs/C++.html



Java

http://java.sun.com


Javascript

http://developer.mozilla.org/en/JavaScript


Lua

http://www.lua.org/


Pascal

http://www.freepascal.org/docs-html/ref/ref.html


Perl

http://perldoc.perl.org/
http://www.perl.org/
http://cpan.org/
http://www.perlmonks.org/


PHP

http://www.php.net


Python

http://python.org/


Ruby

http://www.ruby-lang.org/en/documentation/


Scheme

http://groups.csail.mit.edu/mac/projects/scheme/


TCL

http://en.wikibooks.org/wiki/Programming:Tcl



–

General Programming

Structure and Interpretation of Computer Programs


Regular Expression

http://www.regular-expressions.info/






Mystery of Music Unveiled
anil — Sun, 17 Aug 2008 18:27:51 +0000
Ever since I started learning Guitar, I have been wondering what makes music so pleasing to our ears. And what makes a chain of tones a music which, if played independently, has no charm. My guitar tutors taught me lessons such as  “you need to come back to the Key when you conclude your melody.” I obeyed them; because they worked all the time. We have been following such rules to play and create music. In this article, I will describe my findings on why those rules are rules.
This article requires an entry-level knowledge of the western music theory. So readers of this article are supposed to know the following:

notes in a musical keyboard and their names
sharps and flats
what a musical scale is

If the above terms are new to you and still you want to continue reading this article, I would suggest you to learn them from the Connexions Music Modules. Also read Music Theory Wikipedia page and from Ricci Adam’s musictheory.net.
In addition to knowing the above it is also assumed that, when you hear the same musical note twice–one after the other, you must be able to make out that they are the same. And when someone plays your favourite tune on her guitar and she slips a note or two, you can clearly make that out too.
***
Well, let’s dig into the matter. For the sake of simplicity, we will discuss melodies to generalise music as melodies are music in the simplest form.
When you listen to a melody you can feel the following (recall your favourite melody; if nothing comes to your mind listen to this AirTel jingle):
It starts and a phrase is developed

It continues that way taking us to ecstasy

It starts a kind of coming back

It reaches home (we feel completion)
My curiosity was why this happens and what makes the mind enjoy the progression (the sequence in which those musical notes are played). 
To proceed further with the discussion we need to understand a major concept in music called Tonal Interval.
Tonal Interval
Tonal interval is the “musical distance” between two notes on a keyboard. The tonal interval between any two adjacent notes is called a “semitone” or a “half step”. Similarly the distance between any note and the third from it is called a “whole tone”. For example the interval between the note C and C^# is a semitone or a half step. The interval between the note C and D is called a whole tone or a full step. This way you can enlist the distance between any two tones in the keyboard.
Try playing all two-note (one after the other) combinations. Start with two notes of one half step apart and then a full step and then one and half step and so on. While doing so give attention to how each pair sounds like and feels like. You would notice that certain combinations (or the transition) sounds better than another. Likewise certain combinations sound horrible or unstable.
Well, you just learned one of most important fundamentals of music. Now let us understand two aspects of tonal interval.
Consonance and Dissonance
The origin of the word Consonance is from the Latin word “consonare” which means simply “sounding together”.  But in the theory of music this is used to refer a tonal interval that sounds stable, pleasant and completely at rest. The most familiar example to illustrate a consonant interval would be the “ding-dong” of door bells or wall clocks.
If you try to figure out the interval of the “ding-dong”, most likely the interval would be two whole steps (this interval is called major third and is used in all dual tone applications around us such as door bells, car horns, etc.). That means if you start with E (“ding”) and the note C (“dong”) which is two whole steps down makes the combination. Now if you play D^# (which is nearer to C by one half step) instead of E, you will note that it doesn’t sound as sweet. Repeat this experiment by reducing the interval by one half step each time. The pleasant sounding interval will become increasingly harsh as you proceed and you will hear the harshest when you play the “ding” just one half step away (i.e. C^#) from “dong”. This harshness is the opposite of Consonance and it is called Dissonance. 
So the interval between any two notes in the twelve-tone system is identified to have a certain degree of consonance or dissonance. See the following table which describes the quality (degree of consonance or dissonance) of all possible tonal intervals in the twelve-tone system.


Note
Tonal Distance/Interval
Quality


C
none
pure consonance


C#
half step
very dissonant


D
one whole step
dissonant


E^b
three half steps
mild consonant


E
two whole steps
very consonant


F
five half steps
pure consonance


F#
three whole steps
ambiguous


G
seven half steps
pure consonance


A^b
four whole steps
mild consonance


A
nine half steps
very consonant


B^b
five whole steps
mild dissonance


B
eleven half steps
very dissonant


C
six whole steps
pure consonance


Please note that whether the consonance and dissonance effects of tonal intervals are absolute/universal or enculturated is a subject for debate. However here we just need to know that each tonal interval has an associated degree of consonance or dissonance to understand the concepts being discussed here.
Also note that the three-whole-step interval is neither a consonant or a dissonant. This interval is called diminished fifth. I have been told that diminished fifth (also known as devil’s interval) was banned in early church music because of its ambiguous nature. While playing this interval it does give a tensed and horrible feeling. This interval was first used in a song by Black Sabbath and then several bands after that.
This consonance and dissonance in varying degrees appear in a melody as it progresses. As we have seen earlier, our mind becomes restless when the melody proceeds to a dissonant interval and will feel peace when it enters a consonant interval. This sequential progression of consonant and dissonant intervals of varying degrees produces  a sensation of movement through time. It is the combination of dissonance and consonance, tension and relaxation that defines this movement. This movement give a musical direction to the melody.
This is somewhat similar to what we feel when we read a novel. The thread of the story passes through tensed situations (dissonance) during which our mind becomes curious and long for a resolution (consonance) which we feel when we reach the phrase “they lived happily ever after.”
Now let us experience a simple progression to illustrate this. Try playing the following note sequence in keyboard. 
(Press and hold each key for one second. Keys are numbered for easy understanding.)
C[1], D[2], E[3], E[3], D[2], C[1]
As we move from note to note, we feel respective intervals. An interval can either be dissonant or consonant. Here we can experience the following with the progression:
C: -

D: dissonant (tension)

E: very consonant (some what relaxed)

E:  very consonant (some what relaxed)

D: very dissonant (climax)

C: pure consonance (resolution)
When we reach the last note C, we feel the that the melody came to a conclusion. Now let us see how we can make this simple melody a little more interesting. Try this sequence. 
(Press and hold each key for one second. Keys are numbered for easy understanding.)
C[1], D[2], E[3], D[2], B[0], C[1]
(Notice that the note B is numbered zero because it comes before the note C)
You would agree that the this sequence sounds more enchanting than the previous one. This is because of the musical motion created by  the sequence of tension and relaxation (dissonance and consonance) is more vivid in this sequence. Let us analyse it more carefully.
Have a look at the note sequences once more. Both the sequences give a feel of resolution by returning to the note C. But the second sequence is definitely sweeter than the first one. This is because, we simply postponed or delayed the resolution by playing the extra note B which intensified the drama, prolonging the mystery and sustaining the listeners attention! This is how sweet melodies are created.
It would be interesting to note that its is the interval between the notes is what creates music. Next time when you listen to a sweet melody remember that your mind is being tingled by those tonal intervals! And the background score in the movie is playing a dissonant interval when the villain shows up!
***
What we discussed here is the music in its simplest form. The songs and compositions we enjoy are more complex than simple melody. It contains harmony which brings in multitude of intervals at the same time. The effect of which is easier to feel than analysing it. But the fundamentals remain the same: tonal intervals, consonance, dissonance and the influence and the resulting feeling effected in our mind by a particular progression.
***

Bibliography
1. Pen, Ronald, Ph.D., Introduction to Music, 1992, McGraw-Hill Co. Singapore.

2. http://en.wikipedia.org/wiki/Interval_(music)

3. http://en.wikipedia.org/wiki/Consonance_and_dissonance

4. http://www.music-cog.ohio-state.edu/Music829B/notes.html



Learn IP Networking
anil — Sun, 06 Jul 2008 17:33:59 +0000
I get emails from fresh computer science graduates on career guidance. Many of them want to enter the field of computer Networking and computer security. So they ask me what should they do. I have understood that many of them already done course like CCNA, RHCE, etc. hoping that those certification will help them to start their career. To my surprise I understood that they successfully obtained their certification despite the fact that many of them don’t even know the basics of computer Networking.
If someone asks my opinion about joining such a course, I discourage them, unless they know the fundamentals of Networking. And I suggest them to go through their text books once gain before they spend money on any such course. Many of them asks me to suggest a list of things they are supposed to know to start a career in computer Networking. This prompted me to prepare a list of articles entirely from the Web which will enable a fresh-out-of-college to gain knowledge and enable him to find an entry level job in computer Networking.
Here is the list I prepared. Go through it and I am sure that you can start a Networking career with confidence once you finish it. All the best.
***
o Start your journey here [compnetworking.about.com].

This is a very good tutorial with a very good breadth of coverage. This will help you understand basic concepts and to build a vocabulary on the subject.
o Learn Linux. Linux is your best friend in understanding what really happens behind the scenes. I would recommend you to use a distribution like Debian Linux and not the ones like Ubuntu. If you use a Linux distribution with well-designed GUI such as Ubuntu, you will take longer to understand what you are actually doing. Once you learn what’s is happening underneath, you can do the same on Windows and Ubuntu insightfully.
This page [www.debian.org] will help you get started with Debian Linux.
o Once you have learnt Linux, you start the real learning here [linux-ip.net]. Don’t get discouraged that this tutorial is too much Linux specific. You gotta learn some tools to learn hands-on Networking and I would say that Linux is the one of the best tools around. So go ahead and graduate in Linux Networking.
o Now you can move on to Windows. Windows too has got a bunch of useful command line tools. Start with them. This tutorial [commandwindows.com] will help you to get acquainted with those commands.
o Now you are familiar with basic Networking concepts, principles and tools. Now you can have a look at Windows Networking. I am sure that you will be able to look at the already-familiar mechanisms of Windows such as File Sharing and Firewalling with a deeper insight now. Read it here [compnetworking.about.com].
o Still most of the Network administrator jobs are in medium to large organisations running Microsoft Windows. I think now you have reached a position to design and implement a Windows Network. This Cisco Web page will help you to get started.
o Now, send me your rÃ©sumÃ©   You will get to know IP Networking inside out at Linuxense.
PS: Let me know if this list of URLs helped you improve your knowledge. More importantly, if you come across a useful URL, please forward it for inclusion here so that others too will be benefited.



May 1 Ride (2008)
anil — Mon, 05 May 2008 16:09:20 +0000
[Correction 1: (corrected text in bold) ... straight Highways and a deviation at any point towards the west  will take you to some beach ...]
[Correction 2: Thenmala is around 10Km ahead from the KTDC restaurant we had lunch at. This restaurant is exactly opposite to the Palaruvi road in NH208]
We at Silver Bullets have been consistently riding on all one-day holidays for the last one year. The latest in the series was May 1. One-day rides normally covers a round-about distance of around 300Km. 
In Kerala you can choose to ride along the coast lines (straight Highways and a deviation at any point towards the east will take you to some beach) or through the eastern sides of Kerala which are full of twisties and hills. Most of the time we choose to ride through the eastern side called Western Ghats. This ride was no exception.
By Wednesday we kind of finalised the route: Trivandrum, Ayur, Anchal, Punalur, Achancoil, Shenkottai and decided to choose the return route along the way depending on the road conditions and mood.
There were not many takers for this trip. SB Trivandrum members were unusually busy with work/family this time. There were just me, Sankar (cutcrank) and Bala. But we had a few guests this time: my buddy Binuraj (who originally suggested the route), then Gokul and Shahu (both from Linuxense). Binuraj rides a Honda Unicorn. Gokul rides a brand new TVS Apache RTR 160 (who is running-in the engine as per the MotoTune theory and the reason for participating in this ride) and Shahu was pillion riding.
We gathered at Paruthipara at around 6:00am. Weather was cool and crisp and luckily the unexpected downpour prevailed since last week has stopped just the day before. So we had a very nice morning and we hit the MC Road by 6:30. This time too I was the sweep and cutcrank was the obvious choice to be the lead.
Ayur, the first deviation, was around 50Km from Trivandrum and then another 10Km to Anchal. We reached Anchal by 7:30am. Binuraj is a native of Anchal and we waited for him to join us. By that time cutcrank took out his Canon EOS400D and started flashing. Here is one pic from that lot (which I clicked): 
Our next destination was Punalur which is 12Km away from Anchal towards the East. We had a nice breakfast there and headed towards Achancoil. To those who are planning to venture this route: you need to take the Ranni route and take the road that goes to the right at around 4Km (the junction is called Alimukku). It’s very easy to miss this deviation; some of us did. 
I used to accept hitchhike requests, when I’m riding, from locals if my luggage permits; especially from aged people. I kind of chat with them and get some geo/socio information from them. I found it interesting. This time too, I offered ride to an ammavan (uncle by age). But this time I was in a kind of trap.
As mentioned above, I missed the deviation at Alimukku. I was riding along the Ranni highway enjoying the scenery and the weather, one aged man in his 70s asked for a ride. I offered. As usual I started chatting with him and a few minutes later I explained where I’m heading. Then he realised that I’m a lost guy heading in a wrong direction! He said with exclamation that I lost my way. And the situation was more interesting because he was in trouble too: I either should get him back to the place where I picked him up or I should take him to the next point where he can get another ride (or catch a bus). I said to myself; well, I’m out here to ride and why not do a social service. And I decided to ride three more kilometres to the wrong direction and dropped him in a junction before I headed back. 
That’s one of the good sides of motorcycling I enjoy. We can never do (or we don’t prefer to do) this if we are driving a car. With a motorcycle you are more free, more local and you can afford to show some random act of kindness.
***
Punalur Achancoil is the leg in which we leave civilisation and enter forest.  Houses and grazing cattle begin to disappear and the green lush will get thicker. What you would notice while in a forest is the “deafening” silence. We stopped at several places to enjoy that and roamed around to get the feel of oxygen-rich unpolluted atmosphere.

Achancoil is a township in the midst of the forest and at the border of Kerala and Tamil Nadu. People speak Malayalam there. I think they can speak Tamil too. We approached a local corner shop in Achancoil hoping to get some drink.  We were totally tired by then. Bala was prudent enough to stock a few bottles of water but the terrain combined with this riding style made them pop out and fell down along the way; leaving all of us thirsty and tired. We found pre-packed sambharam in the corner shop. But that guy discouraged saying that that was not good (it may be of low quality butter milk prepared for local people for a cheap price) and offered Soda-Naranga Vellam (Neembu paani). Surprisingly he has got a Mr. Butlers Sodamaker in his shop and he prepared enough glasses of drinks for us in no time. We were recharged and ready to proceed to Shenkottai.
 
Achancoil–Shenkottai is more scenic. It has some excellent twisties for those who enjoy it. cutcrank and Binuraj were racing through the twisties pushing their bikes to the limits. And we reached Shenkottai by around 1:30pm. Our next priority was to find an eatery.
Shenkottai seemed deserted. May be because it was May 1. And we found it strange that we could not locate any restaurant. To add to the difficulty, majority of the team voted for a non-veg (read “mutton”) meal. So we checked with the locals for any “non-vegetarian” restaurants around. They said “yes” and pointed us to some direction. But, surprisingly, each time we landed in front of a vegetarian restaurant! Then we found out a small bug in our communication: the “non” in “non-vegetarian” was not understood by the locals and so it was ignored!
Gradually we realised that we were not going to get non-veg food in Shenkottai. The weather was gruelling; the temperature must be above 35 though humidity felt to be lower than that of Trivandrum. We decided to have some soft drink and head back to the Kerala border. 
For our return trip we decided to take the Ariankavu, Thenmala, Madathara, Nedumangadu, Trivandrum route. NH208 takes us from Shenkottai till Thenmala. NH was excellent till we cross the Kerala border. After Ariankavu it was totally broken. It was an acid test for the shocks and an endurance test for our body. At Thenmala we stopped at the KTDC restaurant for lunch (finally we found a place!).
But disappointing some of the ardent mutton fans in our team, they had only chicken in stock. But [luckly] our folks lost their ability to distinguish mutton from nicely prepared chicken. So they didn’t make much noise this time. We enjoyed  homely meal there, took a 20-minute rest and we were ready for the last leg.
***
It was around 3:30pm when we started from Thenmala. There were around 80Km lying ahead to reach Trivandrum. We decided that there won’t be any scheduled stops hereafter and we would stop only on as-needed basis.
Kallada dam is located in Thenmala and it was visible from the road we took. We can ride over the dam. There weren’t much tourists there when we reached that spot. So we decided to have a stopover and take some snaps. Here are some: . Bala riding down the dam: 
Binuraj said goodbye at Kulathupuzha (5Km down from Thenmala) and deviated to Anchal. From Kulathupuzha to Trivandrum, were almost solo riding. cutcrank and Gokul were riding ahead with considerable lead, followed by Bala and me.
We were safely back home by around 6pm covering around 300Km. Rough roads and lack of physical activities these days made us tired and caused some body aches here and there. But we were totally charged. I found a great way to fight the hang over: plan the next trip! Yeah, we are going to ride through Munnar soon!!!
–

1. cutcrank’s Picasa album.
2. Binuraj’s Picasa album.

Note	Tonal Distance/Interval	Quality
C	none	pure consonance
C#	half step	very dissonant
D	one whole step	dissonant
E^b	three half steps	mild consonant
E	two whole steps	very consonant
F	five half steps	pure consonance
F#	three whole steps	ambiguous
G	seven half steps	pure consonance
A^b	four whole steps	mild consonance
A	nine half steps	very consonant
B^b	five whole steps	mild dissonance
B	eleven half steps	very dissonant
C	six whole steps	pure consonance