Silviu's Blog

Update CLOB/BLOB procedure

2009-09-29T11:44:00.006+03:00

For those who wonder how to change and update a LOB in Oracle. There are different solutions for this and the easiest one is by using the procedure listed below. For cases where heavy data processing is needed better use Java/C#, Oracle has support for reading and updating lobs through their respective drivers (like jdbc).


DECLARE

pattern VARCHAR(100);
replacement VARCHAR(100);
dbData CLOB;
tempData CLOB;
maxBufferSize INTEGER := 32767;
tempBuffer VARCHAR(32767);
pos INTEGER := 1;
dataSize INTEGER;

--------------------------------------------------------------------------------
-- Edit the following part as needed:
--
-- data2        is the CLOB column to update
-- test         is the table for data2
-- pattern      is the string to be replaced
-- replacement  is the string to insert in place of pattern
-- WHERE clause
--------------------------------------------------------------------------------
CURSOR cr is
SELECT data2 as dbData
    FROM test
    WHERE id = 1 
    FOR UPDATE;

BEGIN

pattern := 'test';
replacement := 'test123';
--------------------------------------------------------------------------------

FOR r IN cr LOOP

dbms_lob.createtemporary(tempData, TRUE); 
dataSize := dbms_lob.getlength(r.dbData);

dbms_lob.copy(tempData, r.dbData, dataSize);
dbms_lob.trim(r.dbData, 0);

WHILE pos < dataSize
LOOP
    dbms_lob.read(tempData, maxBufferSize, pos, tempBuffer);

    IF tempBuffer IS NOT NULL THEN
        --tempBuffer := replace(tempBuffer, pattern, replacement); -- this is simple string replacement for oracle 9i or below
        tempBuffer := regexp_replace(tempBuffer, pattern, replacement); -- this provides regexp in oracle 10g and above only
        dbms_lob.writeappend(r.dbData, length(tempBuffer), tempBuffer);
    END IF;
    
    pos := pos + maxBufferSize;
END LOOP; 

dbms_lob.freetemporary(tempData);

END LOOP;

COMMIT;

EXCEPTION
    WHEN OTHERS THEN
        ROLLBACK;
        RAISE;
END;
/

Monitoring my Win systems

2009-07-23T21:04:00.008+03:00

Many times I miss the tools from Linux/Unix to monitor or to understand what's going on my Windows PCs. I'm speaking about tools like: ps, top, glimpse, vmstat, strace, strings, free, uptime, lsof, uname, hdparm, df, du ... I hope you got the ideea by now.

To my surprise I found similar tools for windows, provided by free on MS site. I wonder why they don't make the tools I'll tell you next be by default part of Windows. The tools are provided as part of a package called sysinternals (sysinternals was a company that initialy developed the tools but is now part of MS).

I will refer to only three of sysinternals tools (there are many more, see their website):

1. Procexp which covers, making a parallel to Linux, the functionality of ps, top, vmstat, strace, free, uptime, uname and probably more than that.

This is how the main screen looks like:

Procexp is much more better than the default windows Task Manager, with this tool you can see for example how much CPU DPCc (direct procedure calls) are taking. In fact the info reported for each process is impresive, see next screenshot:

Procexp can be downloaded for free from here.

2. Tcpview, displays in a graphical maner all the open sockets in your Windows system. One can see all conections (TCP and UDP), all opened ports and the processes that opened those connections. Is a good tool in case you suspect something wrong is going on with your PC. Conections can also be closed from same tool.

Download Tcpview from here.

3. Filemon, this tool has the same function as the lsof in Linux. Displays all opened or memory mapped files and the coresponding processes that use those files. Very handy if you want to see which files are accesed by a certain process. Or to see failed attempts to access inexisting files that may make some processes to crash. See more about Filemon at this link.

Symbolic links in Windows

2009-06-21T14:08:00.000+03:00

I often miss the file linking mechanism present in Linux/Unix. File linking is different from what Windows' file shortcut can do. Most of Windows application can't take a file shortcut an use the target of that shortcut instead of the shortcut file itself. For example I keep all my programming projects in one place on my file system and some of those projects are web project that I need to test by running them using Apache web server. As my server's document root is different from my projects' location, I need to copy the project to Apache's document root or easier link that project to a place in my server's document root. This is how I found about Junction Link Magic which allows me to do symbolic linking in Windows or using their words allows to create "junction points":

A junction point is a special type of reparse point. Reparse points are redirections in the Windows file system. There are 3 types of reparse points:

Symbolic links - can be thought of as a shortcut to a file or folder elsewhere in the file system
Junction points - can only point to a folder
Mount points - is a folder on a disk that points to an entire disk volume

Junction Link Magic will list all 3 types, not only junction links. With Junction Link Magic, you can also create and remove junction links.

A junction point is a technology for a folder to be grafted into another folder on the same local computer.

This might not seem like a big deal, but it can remove a lot of clutter. It also helps a lot when moving programs from one place to another, since just about every program in the Windows world expects to never be moved from the directory it was installed in.

The tool is working with NTFS 5.0 or above file systems only, so no FAT support.

Hijackthis

2009-06-09T11:28:00.000+03:00

Even if you have antivirus and/or spyware monitoring tools installed on your system some of the newest malware can be get just by visiting some websites or let’s say by using a USB storage device to transfer data between systems. For me is very handy to use a tool that shows what is running on my system, what are the custom registry changes, what custom services are running at start up and so on. So I found Hijackthis from TrendSecure (they provide the tool for free). I save logs generated by this tool at different time periods and compare them. The differences may indicate malicious software running on my system.

The tool can be downloaded at http://www.trendsecure.com/portal/en-US/tools/security_tools/hijackthis

This is a quote from their site:

"HijackThis™ is a free utility which quickly scans your Windows computer to find settings that may have been changed by spyware, malware or other unwanted programs. HijackThis creates a report, or log file, with the results of the scan.

IMPORTANT: HijackThis does not determine what is good or bad. Do not make any changes to your computer settings unless you are an expert computer user.

Advanced users can use HijackThis to remove unwanted settings or files."

SSH daemon in Windows

2009-03-20T14:49:00.002+02:00

This is a good tutorial on how to install a free OpenSSH service in Windows:

http://pigtail.net/LRP/printsrv/cygwin-sshd.html

Cygwin and friends

2008-10-30T11:29:00.007+02:00

I'll present ones of the most useful tools for Windows, this is about how to bring your Linux/Unix environment to the operating system of choice of all corporates. The tools we discuss further do not require you to be an administrator of your Windows box so these can really be installed anywhere.

Cygwin is a set of tools starting with a Windows implementation of BASH shell, gcc compiler and continuing with almost all the popular Linux/Unix applications ports for Windows. To give a few examples: ssh daemon and client, Apache server, vim, gawk, perl, pyton, ruby and the list can go on.

To install you need to have a broadband Internet link and the rest is peace of cake. Just go to www.cygwin.com download the setup.exe file run it and the install process will start. You have to set some paths and chose which applications to install. Careful, if you chose all of them it may take hours to download and install. I personally chose the default applications and install all other when I need them (and only those I need). To select an application to install (see last image) click on New column of respective application until you get the version which will be installed. The setup process can be run as many times you need without affecting the existing installed packages, it can install new apps, delete old ones and update applications as you need.

After the installation is completed the environment can be used by opening the console (usually a link to it is created on your desktop).

Again I personally don't like the default console (windows console) for its poor text handling features so I use a replacement (wrapper console) named Console :). It can be downloaded from here: http://sourceforge.net/projects/console. It even has support for transparency, here's a screenshot (running mc):

If Cygwin didn't convinced you, there are some other options for same Unix environment like tools under Windows:

MSYS (with MinGW) is as their website says:
"... a collection of GNU utilities such as bash, make, gawk and grep to allow building of applications and programs which depend on traditionally UNIX tools to be present. It is intended to supplement MinGW and the deficiencies of the cmd shell.

An example would be building a library that uses the autotools build system. Users will typically run "./configure" then "make" to build it. The configure shell script requires a shell script interpreter which is not present on Windows systems, but provided by MSYS.

A common misunderstanding is MSYS is "UNIX on Windows", MSYS by itself does not contain a compiler or a C library, therefore does not give the ability to magically port UNIX programs over to Windows nor does it provide any UNIX specific functionality like case-sensitive filenames. Users looking for such functionality should look to Cygwin or Microsoft's Interix instead."
UWIN (open source from AT&T research labs). It is presented as: "The UWIN package allows UNIX applications to be built and run on Windows XP/2000/NT/ME/98/95 with few, if any, changes necessary."
Interix (known as Microsoft SFU). Is like all other environments and this are some guidelines from its builders:

"Why use SFU? SFU is POSIX, SFU is UNIX

you can compile, edit and run your source code like on every other UNIX OS

use your Unix know-how to write Windows software

use !!!one!!! source tree (proven by my own projects) to create Unix, Mac OS X and now Windows software

you can login with telnet or openssh, using your bash (and now tcl) to get your work done and finally use the already known Microsoft applications on your desk (even remote with "rdesktop")

save space and money for one additional workstation (on your table)

SFU fits very well into the Windows environment (no path-name-horror-trip with cygwin)

Admin a Windows system with Unix utilities

Why not use SFU? (already known Windows limitations still exist)

no root user available (chosen restriction to link SFU into the windows user-management)

you can not create files like "odd\\\[\]*?\{\}name" (NTFS limitation)

a user started server can listen on low ports (security hole)

multiple servers can listen on the same port. The first one wins, but the second one does get !!no!! error-msg

FIFO speed is slow (~10 times slower than Linux)

application speed is high, filesystem access speed is medium

AEC 2005-09-09 I recently read Microsoft is going to stop developing SFU as an environment, but continue using it as a library for use with some of their server products. LV Actually, the code previously known as Interix or SFU has become bundled into the latest service pack for Windows 2003, and will also be included in the next generation of Windows. Read the various technical web sites from last August and September regarding Microsoft's plans. Note that the new abbreviation for this component is SUA."

Mind Mapping

2008-09-19T12:56:00.004+03:00

I didn't see to many people using mind mapping although the technique (method) is old and not necessarily linked to a software tool. Mind mapping is a method of organizing the ideas/thoughts around a central key word that represents the original notion around which the whole thought process takes place. It may be the unorthodox support for brainstorming also can help in taking notes, memos and I even think of minutes of meetings.

For an in deep description on how it is done and where can be applied try Wikipedia's articles Mind Map and List of Mind Mapping Software.

As a software tool to apply mind mapping I tried Freemind. On Internet I found Freemind as being very appreciated amogst profesionals. I personally try it few times but I think to make use of it more often. It can be used in any field from designing software to depicting ideas in Asimov's work :). Some screenshots in the right of the page. Current stable version is 0.8.1, the 0.9 version is in beta.

Freeware and open source design tools

2008-09-06T11:14:00.008+03:00

I'm not a visual arts designer but occasionally I need to use some tools to visualize data. This is a list of software that can do a lot and for free:

1. GIMP - it's open source and available for Windows, Linux, Unix (BSD and Solaris) and Mac. Until now it successfully replaced Photoshop for all my image editing needs. It's a powerful tool but it takes some time to learn, I would suggest starting with GIMP's excellent tutorials.

2. Google SketchUp - is a freeware 3D editing software from Google. It's main advantages are: easy to learn, easy to use and have a big models library already created. The main disadantage is that this software is only available for Windows and Mac (no Linux/Unix version).

3. Dia - it's an open source Gnome project. As the software is presented on its web site:

"Dia is inspired by the commercial Windows program 'Visio', though more geared towards informal diagrams for casual use. It can be used to draw many different kinds of diagrams. It currently has special objects to help draw entity relationship diagrams, UML diagrams, flowcharts, network diagrams, and many other diagrams. It is also possible to add support for new shapes by writing simple XML files, using a subset of SVG to draw the shape.

It can load and save diagrams to a custom XML format (gzipped by default, to save space), can export diagrams to a number of formats, including EPS, SVG, XFIG, WMF and PNG, and can print diagrams (including ones that span multiple pages)."

It's reliable, easy to learn and use and the precompiled binaries are available for Windows and Linux.

4. Processing - As described on their web site:

"Processing is an open source programming language and environment for people who want to program images, animation, and interactions. It is used by students, artists, designers, researchers, and hobbyists for learning, prototyping, and production. It is created to teach fundamentals of computer programming within a visual context and to serve as a software sketchbook and professional production tool."

This means that a little programing is needed to be able to visualize the data. I see it as a compromise between great flexibility in solving complex visualizing problems and the complexity of using a programming language. The programming part was reduced to using very basic commands (which resembles natural spoken language) which are easy to learn and use. This tool is available for Windows, Mac and Linux.

Some screen shots of running a Processing example:

Left picture is the editor window while in the right side there's the result of simulating a fractal tree at two different angles.

Find and replace all (unix/linux/windows shell script)

2008-07-18T09:56:00.014+03:00

This script will replace all occurrences of a given string within all files specified. In windows the script can be run through cygwin.



#!/bin/bash

function usage
{
echo "*"
echo "* Usage: ${0} search-string replace-string path-to-search"
echo "* Remember to escape special characters in search-string, replace-string and path-to-search."
echo "* Do 'man sed' for more on special characters"
echo "* e.g. ${0} br> br\/> dir_path"
echo "* will replace all br> with br/> in all files under dir_path directory"
echo "*"
}

if  [[ ${#} == 3 ]] ; then
echo "This tool will PERMANENTLY MODIFY some of your files."
echo "Depending on provided input you may DAMAGE your files."
echo "Having a BACKUP of your files is highly recommended."
read -p "Are you sure you want to continue?(y|N): "

if  [[ ${REPLY} == "Y" || ${REPLY} == "y" ]] ; then
   echo "Searching ..."
   for file in `find ${3} -type f`; do
       if grep -q ${1} ${file} ; then
           echo "Replacing ${1} with ${2} in ${file}"
           sed -i s/${1}/${2}/g ${file}
           echo ${file} >> modfiles.lst
       fi
   done
   echo "Job done. A list of all modified files can be found in `pwd`/modfiles.lst"
fi
else
usage
fi

But I guess this is too much for a Unix/Linux user so if you want a fast one line way of searching and replacing all patterns you may use this:

find /search/path/ -type f -name '*.txt' -print -exec sed -i s/pattern/replace_string/g '{}' \;

This will replace all pattern strings in your text files (*.txt) under /search/path/ directory (recursive search within all sub-directories) with replace_string.

More on finally java statement

2008-04-03T12:20:00.012+03:00

Take this sample code:


public class JavaTest
{
   /**
    * @param args
    */
   public static void main(String[] args)
   {
       try
       {
           throwAnException();
           System.out.println("Text not displayed.");
       }
       catch(Exception e)
       {
           System.out.println("Exception from throwAnException: " + 
                              e.getMessage());
       }
   }
 
   public static void throwAnException() throws Exception
   {
       try
       {
           throw new Exception("Some exception");
       }
       catch(Exception e)
       {
           System.out.println("throwAnException: " + 
                              e.getMessage());
           throw e;
       }
       finally
       {
           return;
       }
   }
}

What do you think the output will be? The finally block here contains a return statement, although this will generate a warning at compile time the code is compiled and running without any error.

Be careful that finally blocks containing return, break or continue statements are giving the control back to the points were they were called so in the above case the control will be given back to main without any exception being caught in main.

A more maintainable/readable code with same functionality like the code above:


public class JavaTest
{
 /**
  * @param args
  */
 public static void main(String[] args)
 {
  try
  {
   throwAnException();
   System.out.println("Text not displayed.");
  }
  catch(Exception e)
  {
   System.out.println("Exception from throwAnException: " + 
                      e.getMessage());
  }
 }
 
 public static void throwAnException() throws Exception
 {
  try
  {
   throw new Exception("Some exception");
  }
  catch(Exception e)
  {
   System.out.println("throwAnException: " + 
                      e.getMessage());
   //throw e;
  }
  //finally
  //{
  // return;
  //}
 }
}

Berkeley podcasts

2008-01-31T11:28:00.000+02:00

When first I found Berkeley is podcasting their courses I said this is really a good chance to take the courses of a big and well known University. So I started few months back to listen, first to a physics course (Physics 10/LS C70V) then to an astronomy one and finally a human nutrition course. And as I plan right know probably I will not stop soon to listen to Berkeley's web casts. Probably I was very lucky to start with Physics 10/LS C70V, or it's unofficial name "Physics for Future Presidents", as I found this course the most informative and entertaining (at the same time) I ever listen to. After having more than five years since I finished my university studies now it feels great to be back to school and having a quality material to listen to. In this program I see a great chance for all those who tell themselves "I want to know more" to actually experience the thought for free and without tight schedules. Finally continuous education is a way to stay awake to all that happens around us, and there are few things going on in the world.

Different way of sharing information

2008-01-30T12:09:00.000+02:00

If you think to share your contact and don't know how, there's a interesting way of doing it. Recently I found a Nokia service (Nokia Mobile Codes) for encrypting information to a dot encrypted picture. The picture can be shared and scanned with mobile applications. This is not a data sharing security tip, is just a funny way of doing things.

The image code of silviupaval.blogspot.com is on the right.