Serge_HID's personal blog

Link to Fox News TV-cast

2008-08-16T08:06:00.001+04:00

http://www.youtube.com/watch?v=H8XI2Chc6uQ
It's a link to the reel I mentioned in the previous post.

Silly Americans

2008-08-16T07:40:00.003+04:00

An interesting reel appeared at youtube.com recently. It's a record from Fox News telecast - a 12 year old girl and a woman are asked about the conflict in the South Osetia. But when they tried to tell the truth about this situation, the presenter said they needed to make a break and after that, when the woman called Georgia and its president, Saakhashvili, an agressor, it turned out that telecast's time was out.
Damn, ok, I understand that the most of americans are brainwashed by mass media (by the way, it reminds me of the Soviet Union, I mean brainwashing), but why do they think they are always right? are they really Gods? Why do they think they can invade Iraq (it's not their territory) and bomb Afghanistan (it's not their territory too, and don't tell me about 9/11, it's all bullshit about Al Qaeda and Ben Laden - dear Americans, spen some time to watch the documentals about Bush and Ben Laden relationship. Actually, there are much more facts about that date)? I even don't talk about Kosovo. But they critisize others when they try to solve their own problems, problems concerning their independence and security.
I can draw a conclusion that either Americans are so stupid to analyze information (yep, it is a bit more difficult than to eat hamburgers and drink coca-cola) either they pretend to be stupid... I hope they just pretend...

CSS positioning (layouts)

2008-08-12T13:26:00.004+04:00

Found a nice simple article about CSS positioning today (http://www.brainjar.com/css/positioning/).
This theme has been a little unclear for me before, especially when I made up complicated jsp-pages. Many thanks to Mike =)

Java -verbose option

2008-05-01T15:46:00.003+04:00

I haven't used any specific command-line parameters running java.exe earlier. But yesterday I ran across the problem that concluded in that JBoss loaded the old version of my class file although I had upgraded all *.war and *.ear files to the last version. I was stuck wondering what the quirk it was.

Finally, I decided to find out where that wacky class has been loaded from. Java -verbose option fitted my task perfectly. It forces to display all class loading results in the console. If you get too many results, you can forward all output to some file using OS specific contstructions like this "> out.txt"

To read more about "Class Loading in Java" you can, for example, here

Recompiling Oracle invalid objects or Brainfucking part 2

2008-04-29T18:38:00.004+04:00

Finally I cloned the production database (RHEL 4, Oracle 10g 10.2.0.3 64 bit edition) to the test one (Fedora Core 8, Oracle 10g 10.2.0.1 updated to 10.2.0.3). All seemed working: I connected to the database using SQLPlus as sysdba and executed some simple SELECT-queries successfully. But as usual there appeared a new trouble :) - when I tried to connect as any user except sysdba, I got the following messages:


Enter password:
ERROR:
ORA-06553: PLS-801: internal error [56319]


ERROR:
ORA-06553: PLS-801: internal error [56319]


Error accessing package DBMS_APPLICATION_INFO

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options

The point is that some objects may have an invalid status after a database upgrade, cloning (especially between 32 and 64 bit editions) etc.

As a remedy for this trouble, you should :

1) Shutdown the database (shutdown)
2) Start up the database in upgrade mode (startup upgrade)
3) Execute utlirp.sql script from $ORACLE_HOME/rdbms/admin directory (@?/rdbms/admin/utlirp 0). You should pass the integer parameter to this script - just pass a zero (0). If you are curious enough, look inside the script for the description.
4) As the prompt will say - shutdown the database again
5) Start up the database in a normal mode (startup)
6) Execute utlrp.sql script (@?/rdbms/admin/utlrp)

Game Over :)

Cloning Oracle database

2008-04-27T13:02:00.009+04:00

Usually developing a J2EE application (sure, it may be not necessary J2EE, but it is so in my case, so I will consider that) you have several environments - at least they are: Development Environment, Test Environment and Production Environment. Production usually contains the most actual 'runtime' information. As for development and test environments it is usually appreciated they would have actual data too. So it's obvious that you need to clone the production database.
You can do that using:

-'cold' cloning: database must be properly shutted down. Then you just copy all datafiles (+ probably redo logs) using OS means. (full step-by-step tutorial on 'cold' cloning you can find at http://www.dba-oracle.com/oracle_tips_db_copy.htm)

-'hot' cloning: This method is used when you cannot afford to shutdown the database. You do not have to shutdown the database, but you must switch database to 'backup mode'. I found a nice step-by-step tutorial how to do it: http://www.shutdownabort.com/quickguides/clone_hot.php

The common incorrect method: to do a database clone without shutdown or switching the database to 'backup mode'. I swallowed this bait too for the first time I cloned the database and hope this caution will help somebody :)

Installing Fedora Core 8 on Linux or Brainfucking part 1

2008-04-25T11:05:00.010+04:00

There appeared a need to install Oracle Database 10g several days ago. All i had was Fedora Core 8 with a command line interface.
As a decent person I started with http://www.oracle.com/technology/pub/articles/smiley_10gdb_install.html. But it turned out this manual is not enough because FC is not supported by Oracle.
Also I read from oracle forums that installing Oracle DB on FC8 "is a real pain". Although I decided not to give up, but to try to get the target.
Firstly, I followed the intructions from http://www.oracle-base.com/articles/11g/OracleDB11gR1InstallationOnFedora7.php:
1) Unzipped "linux_11gR1_database.zip"
2) Changed kernel parameters:
a) created a file "/etc/sysctl.conf":

 kernel.shmall = 2097152
kernel.shmmax = 2147483648
kernel.shmmni = 4096
# semaphores: semmsl, semmns, semopm, semmni
kernel.sem = 250 32000 100 128
net.ipv4.ip_local_port_range = 1024 65000
net.core.rmem_default=4194304
net.core.rmem_max=4194304
net.core.wmem_default=262144
net.core.wmem_max=262144

b)executed "/sbin/sysctl -p" to apply changes immediately

3)added the following lines to the /etc/security/limits.conf file:
oracle              soft    nproc   2047
oracle              hard    nproc   16384
oracle              soft    nofile  1024
oracle              hard    nofile  65536

4) added the following line to the /etc/pam.d/login file:

session    required     /lib/security/pam_limits.so
session    required     pam_limits.so

5) disabled secure linux by editing the /etc/selinux/config file:
SELINUX=disabled

6) installed the following packages:
rpm -Uvh binutils-2.*
rpm -Uvh elfutils-libelf-0.*
rpm -Uvh glibc-2.*
rpm -Uvh glibc-common-2.*
rpm -Uvh libgcc-4.*
rpm -Uvh libstdc++-4.*
rpm -Uvh make-3.*
rpm -Uvh elfutils-libelf-devel-0.*
rpm -Uvh glibc-devel-2.*
rpm -Uvh gcc-4.*
rpm -Uvh gcc-c++-4.*
rpm -Uvh libstdc++-devel-4.*
rpm -Uvh unixODBC-2.*

yum install libaio libaio-devel
yum install unixODBC-devel
yum install sysstat

7) created necessary users and groups:
groupadd oinstall
groupadd dba
useradd -g oinstall -G dba,oracle
passwd oracle

8) created the directories in which the Oracle software will be installed:
mkdir -p /hdd1/oracle/product/11.1.0/db_1
chown -R oracle:oinstall /hdd1
chmod -R 775 /hdd1


9) edited the /etc/redhat-release file replacing the current release information (Fedora release 8 (Werewolf)) with the following:
redhat release 5

10) logged in as the oracle user and added the following lines at the end of the .bash_profile file:
# Oracle Settings
TMP=/tmp; export TMP
TMPDIR=$TMP; export TMPDIR

ORACLE_HOSTNAME=HIDServer; export ORACLE_HOSTNAME
ORACLE_BASE=/hdd1/oracle; export ORACLE_BASE
ORACLE_HOME=$ORACLE_BASE/product/10.2.0.1/db_1; export ORACLE_HOME
ORACLE_SID=O10GSID; export ORACLE_SID
ORACLE_TERM=xterm; export ORACLE_TERM
PATH=/usr/sbin:$PATH; export PATH
PATH=$ORACLE_HOME/bin:$PATH; export PATH

LD_LIBRARY_PATH=$ORACLE_HOME/lib:/lib:/usr/lib; export LD_LIBRARY_PATH
CLASSPATH=$ORACLE_HOME/JRE:$ORACLE_HOME/jlib:$ORACLE_HOME/rdbms/jlib; export CLASSPATH

if [ $USER = "oracle" ]; then
if [ $SHELL = "/bin/ksh" ]; then
ulimit -p 16384
ulimit -n 65536
else
ulimit -u 16384 -n 65536
fi
fi

Now according to that tutorial oracle should be installed successfully, but new troubles appeared as it turned out.

Trouble #1: Runnning ./runInstaller, I got such exception:

Preparing to launch Oracle Universal Installer from
/tmp/OraInstall2005-08-30_10-54-49PM. Please wait
...[oracle@localdomain database]$ Exception in thread "main"
java.lang.UnsatisfiedLinkError:
/tmp/OraInstall2005-08-30_10-54-49PM/jre/1.4.2/lib/i386/libawt.so:
libXp.so.6: cannot open shared object file: No such file or directory
at java.lang.ClassLoader$NativeLibrary.load(Native Method)
at java.lang.ClassLoader.loadLibrary0(Unknown Source)
at java.lang.ClassLoader.loadLibrary(Unknown Source)
at java.lang.Runtime.loadLibrary0(Unknown Source)
at java.lang.System.loadLibrary(Unknown Source)
at sun.security.action.LoadLibraryAction.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.awt.NativeLibLoader.loadLibraries(Unknown Source)
at sun.awt.DebugHelper.(Unknown Source)
at java.awt.Component.(Unknown Source)

Having spent some browsing forums I got the solution - all you need to install libXp:
yum install libXp

Retrying to run installer I got:
Trouble #2: I got the error message something like 'Unable to open display'.
Browsing forums again (forums rule the world :)), I read that X Windows System is needed to be installed, so I did it: X-Server + GUI Gnome
But! There is one small thing - you need to switch to "runlevel 5". You can do this by "telinit 5" [or: "init 3"]

Ok, I got the GUI interface - tried to run damned installer again.
WTF?! This time error message was more informative:
 xcb_xlib.c:50: xcb_xlib_unlock: Assertion 'c->xlib.lock' failed.

gtg - to be continued :)

Testing "google.com"-like sites

2008-02-04T12:42:00.000+03:00

I has been given a task to explore if we can test google-like AJAX sites. I mean when we write something in google search edit box, prompting combo/list box appears, and we must emulate some item choosing.
Using Selenium it seems to be impossible to do that, because Selenium operates in terms of HTML elements, but prompting combo/list box is not reflected in HTML source code (as I understood it's shown using browser features, not HTML - anyways, Selenium IDE doesn't trace such actions too).

Selenium HTTPS support

2008-02-01T12:28:00.001+03:00

Selenium developers suggest four experimental launchers for testing SSL-enabled web pages. Two of them(*chrome and *iehta) work as a proxy and since https doesn't let you simply spoof http headers, Selenium issues its own certificate you have to trust (you can find it inside sslSupport folder of Selenium distributive).
Another two launchers (*pifirefox and *piiexplore) access SSL-enabled web pages directly. In this case there is one trouble consisting in necessity of closing warning messages about authenticity of server certificate (sure, it is supposed that you didn't get a certificate from public authorized CA). Obviously, doing this manually is not accessible.

I see two possible ways to solve this flaw:
1) Create your own CA, issue a certificate for your server and add this CA cerificate to public trusted CA's list on a client PC.
2) This method is more forced and I wouldn't recommend you to choose it, but maybe sometimes it can be a last resort. Moreover, it's platform-specific. For example, for windows you code a program (C++, WinAPI) that finds a warning windows by its title and sends a "close" message to it.

Two kind of spaces

2008-01-29T12:36:00.000+03:00

Damn, I spent two hours discovering the reason of my Selenium test failing.
It turned out that the title of the web page contains non-breaking spaces instead of common ones. I wondered why "s.indexOf(s1)" returns -1, where:
s = "blablablb :: Directions";
s1 = ":: Directions";

Parameters & JUnit Test Suites

2008-01-29T10:51:00.001+03:00

There appeared another one problem with JUnit I faced. My task consisted in composing a test suite from tests that take the same parameters set (with different values, sure).

Let's imagine our test suite like this:

TestSuite suite = new TestSuite();
suite.add(testClass1);
suite.add(testClass2);
suite.add(testClass3);

and you need to pass two parameters to each test class:
// testClass1
(param11, param12)

// testClass2
(param21, param22)

// testClass3
(param31, param32)

As I understand, JUnit doesn't let you any means to do it, but you can get out from this situation using parameterized tests (see the previous post).

Picture 1 shows what is supposed to be done.

Picture 2 shows what you can attempt to do to solve this limitation.

Parameters & JUnit Tests

2008-01-29T10:19:00.001+03:00

I ran across one trouble with Junit tests recently. The point is that you can't pass parameters to JUnit tests directly (only using external storages such as file system objects, databases etc, but it's not always the best way for this), to be more precise you couldn't until JUnit 4. Besides new syntax technics, now it supports so called "parameterized tests" - this means you write a test once and it's possible to run it with a set of defined parameters. Before, you should write a particular test method for each parameter.

For example, you got a class that has a method summing two numbers and you wanna test it using 3 different parameters.
Before, you had to write three separate JUnit methods, it looked something like this:

public TestClass extends TestCase {
public void setUp() {
}

public void test1() {
assertEquals(new MyClass.sum(1, 2), 3);
}

public void test2() {
assertEquals(new MyClass.sum(3, 4), 7);
}

public void test3() {
assertEquals(new MyClass.sum(5, 6), 11);
}

public void tearDown() {
}
}

Since JUnit 4 you can do this simpler:

@RunWith(Parameterized.class)
public TestClass {
int a;
int b;
int res;

// Here you describe a method that returns parameters you wanna use to test "sum()" method
@Parameters
public static Collection getParameters() {
return Arrays.asList(new Object[][] = {{1, 2, 3}, {3, 4, 7}, {5, 6, 11}});
}

public TestClass(int a, int b, int res) {
this.a = a;
this .b = b;
this.res = res;
}

// implements the test method
@Test
public void sumTester() {
assertEquals(new MyClass.sum(a, b), res);
}
}

So, for making parameterized test work, you need:
1) describe method that returns parameters (using @Parameters javadoc)
2) implement public constructor that takes the parameters (source data + probably a right result to make an assert) and saves them into private fields.
3) implement test method

Sony Ericsson "Track ID" feature

2008-01-06T13:30:00.000+03:00

My phone broke once and for all and so I decided to buy a new one. I used LG, 2 Motorola's, Siemens, Nokia before - I prefer to buy different brands every time. Well, they say Samsung's suck, Philips-Voxtel-Sagem didn't seem to be my choice, therefore I shot a glance at SonyEricsson, the more so as I heard a lot of favourable reports about 'em. Sure, I browsed several e-shops sites, read some comments ( by the way, I hadn't thought that comments could have been so useful before :) ) and bought k550i model at last. Well, we came to the point what do I write this for. SE K550i got one wonderful feature called "track id". It lets you a possibility to identify music you listen to, for example, say, you heard a really nice track on the radio going to the work, just choose "track id" function, the phone will record a small song fragment, send it to some server and receive a response.
I don't know how it works so fast, but it actually does.

Ok, I understand that there exist different noise-suppressing algorithms (heh, my first uni exam "Digital Signals Processing" is coming soon). But I wonder how it finds info so rapidly.
Let's imagine that a track snatch is just an array of integers. That is, we got a lot of source integer arrays (tracks) and we got an array (much less) we need to identify, moreover considering FM signal is far from being ideal, so the array need to be identified is not necessary a subset of one of the source arrays (supposing target track is contained in DB).
Any ideas?

Blogging start

2008-01-05T19:48:00.000+03:00

Hm, it's really my first post in internet space. I've finally considered all pro's and con's of writing own blog and decided to start. Sure it takes some amount of time on the one hand, and due to a lot of work, study and ... yep, my girlfriend, I'm supposed to say "No, it's not for me". However, sometimes there appear thoughts you want to share with someone other... not because of loneliness... it's just because sometimes there occur situations you should to tell to probably pretend someone to get into. It's something about this =) I hope you got what I'm saying... I really do.