Engineer inside! so as the idiots.......

Memory leak detection in C,C++ codes and Apps

2012-02-29T11:47:00.002+05:30

On of the major part of C/C++ native application development is the memory management.Allocation and Deallocation of memory on runtime and cleaning memory before exit is hard to keep in touch while development. If OOP is in the best use this can be minimized but still can be a issue. Specially while loading and using 3rd party dll and libraries can cause unknown issues.

Detection of leaks can be done in many ways,

code level
using detection tools.

Code level memory detection is supported by most compilers and there are many libraries to do so. This is almost done in debug mode.
_CRT library example of memory detection.

This is a set of libraries given my Microsoft to monitor memory status in the application:

Before using this you have to include following lines of codes:

#ifndef _CRTDBG_MAP_ALLOC
#define _CRTDBG_MAP_ALLOC
#endif _CRTDBG_MAP_ALLOC

#include
#include

Then after you have to go to a certain function call and check whether there was a memory leak within execution of those lines of codes.

_CrtMemState s1, s2, s3;
_CrtMemCheckpoint( &s1 );
//Run the required function call here...
_CrtMemCheckpoint( &s2 );
if ( _CrtMemDifference( &s3, &s1, &s2) ){
_CrtMemDumpStatistics( &s3 );}

This will print the memory leak details on the debug window.
Ex:

0 bytes in 0 Free Blocks.
481371 bytes in 867 Normal Blocks.
1284 bytes in 4 CRT Blocks.
0 bytes in 0 Ignore Blocks.
0 bytes in 0 Client Blocks.
Largest number used: 1056688 bytes.
Total allocations: 2270062 bytes.

You can Google and find out what the exact meaning of those block types. But what we most identify are the Normal Blocks.
So, to avoid memory leaks, you have to go in to that function and add more of those code and find out the last set of minor codes which cause the memory leak and fix it. Unfortunately there is no easy method to fix those. Because all those are due to you are forgetting to deallocate memory objects allocated earlier.

There are many Memory detection and monitoring tools.Most of those tools are hardware dependent. Because in order to monitor an executing application, it needs to go deep into the application execution. So tools become best when they can go deep in to the Hardware Layer. There for most memory detection tools are products of processor manufacturer like Intel and AMD.

Valgrind [only for linux but superb] [http://valgrind.org/ ]
Very Sleepy[http://www.codersnotes.com/sleepy ]
AMD CodeAnalyzer[http://developer.amd.com/tools/codeanalyst/pages/default.aspx ]
Microsoft Task Manager [a general tool, but to that informative]

You can run your app using those tools and they will give you how each functions, threads, objects are occupying memory in run time. So you can go back to the code and identify those locations and fix.

Memory leak detection, locating and fixing is a time consuming process and it could not be 100% fixable task. But you can identify re-occurring leaks and fix those at first. This will make application long last on run and more reliable. So the application will make more stable. Some memory leaks which occurs on initial memory allocation will not continue to grow through continuously, so may not be that much critical.

So, finally its all about making your critical application more stable and run last long more reliably.

Apache Bar Camp- Colombo 2012

2012-02-27T00:15:00.001+05:30

Today sri lankan techies had a wonderful time with apache at UCSC on

with the help of WSO2 and commitment of special apache people here at colombo.

The session was with 3 keynote speakers, started by Dr.sanjeewa weerawarna, CEO of WSO2. He was giving his valuable time for the newbees and followups with great information of his lifetime story with FOSS.

"The Apache Way" could bring the audience to the interesting of being part of the apache comminuty for the community in more long term basis. The simplest form of "Just F***** Do It" [JFDI] was introduced and mentored on the apache community. Meritocracy vs Democracy was a key on the success of apache, and was only used in case of a evading. Otherwise every individual was the key node on the apache community, not either a big part of huge business could break that synopsis.

Subversion system is the first time machine developed[only usable by committees], which make you secure on pushing any FOSS project on your way and give a try bu JFDI. Its secured, because in any case of fire... you can travel backward through your code base and fix your history to continue with greater attitude in the next comeback.Ross Gardler was stunning on JDFI always.. ;)

So, its all about contribution to all apache with what you can, and its not what they MAY want from you. Let community to decide whether you path is on track and its your responsible to listen to them and make your contributions to better path.Your start might me embarrassing like all committees, members. But its the only way to make sure apache users may not get embarrassing.

So, there have bee the announcement of Google Summer Codes. Prepare you time for it as well.

I would like to thank Nick Burch, Ross, Dr.sanjeewa and the srilanan officials and the community for the great event.

Tomorrow is time for BigData at 2nd day. so its time to have a snap before being late tomorrow at virtusa auditorium.

see you with some words about BigData. Thank you.

New programming slang - Programming

2012-02-26T23:02:00.000+05:30

There was some interesting post on a site which sumarizes content from stackoverflow.com. As it was pretty nice, i thought of republishing here for my personal reference. So, you guys n grls please don't read this. It can be a copyright issue for me.... ;)

here is the post for you http://umumble.com/blogs/Programming/321/

Yoda Conditions
The act of using if (constant == variable) instead of natural if (variable == constant),; for example, if (4 == foo). Because it is like "if it is the blue – this is the sky" or "if that is tall – this is a man."

Pokémon Exception Handling
When you catch all the exceptions and then you try somehow to analyze them.

try{
          //code
      }catch ( Exception ex){
          if( ex instanceof SubException){             
              //code
          }else if(ex instanceof SubSubException){
              //code
          }else{
              //code
          }
      }

Discuss an example here

Egyptian brackets
This is the style of brackets, when an opening bracket is placed at the end of this line:

if (a == b) {
    printf("hello");
}

Why do we call this style "Egyptian brackets?" Compare the location of the brackets with the location of the hands in this picture:

(This style of brackets was used in the famous book of Kernighan and Ritchie "C Programming Language", so it is also known as the style of K&R).

Different types of bug reports

Smug Report
A bug report submitted by a user who thinks he knows a lot more about the system’s design than he really does. Filled with irrelevant technical details and one or more suggestions (always wrong) about what he thinks is causing the problem and how we should fix it.

Drug Report
This is a bug report so utterly incomprehensible that whoever submitted it must have been smoking crack. The lesser version is a chug report, where the submitter is thought have had one too many.

Shrug Report
This is a bug report with no error message or “how to reproduce” steps and only a vague description of the problem. Usually contains the phrase "doesn’t work."

A Duck
A feature added for no other reason than to draw management attention and be removed, thus avoiding unnecessary changes in other aspects of the product.
This started as a piece of Interplay corporate lore. It was well known that producers (a game industry position, roughly equivalent to PMs) had to make a change to everything that was done. The assumption was that subconsciously they felt that if they didn’t, they weren’t adding value.

The artist working on the queen animations for Battle Chess was aware of this tendency, and came up with an innovative solution. He did the animations for the queen the way that he felt would be best, with one addition: he gave the queen a pet duck. He animated this duck through all of the queen’s animations, had it flapping around the corners. He also took great care to make sure that it never overlapped the "actual" animation.

Eventually, it came time for the producer to review the animation set for the queen. The producer sat down and watched all of the animations. When they were done, he turned to the artist and said, "That looks great. Just one thing – get rid of the duck."

Refactoring
The process of taking a well-designed piece of code and, through a series of small, reversible changes, making it completely unmaintainable by anyone except yourself.

Stringly Typed
It is a riff on strongly-typed. It is used to describe an implementation that needlessly relies on strings when programmer- and refactor-friendly options are available.
Examples: Method parameters that take strings when other more appropriate types should be used. On the occasion that a string is required in a method call (e.g. network service), the string is then passed and used throughout the rest of the call graph without first converting it to a more suitable internal representation (e.g. parse it and create an enum, then you have strong typing throughout the rest of your codebase).
This is message passing without using typed messages etc. Excessively stringly typed code is usually a pain to understand and detonates at runtime with errors that the compiler would normally find.

Doctype Decoration
When web designers add a proper DOCTYPE declaration at the beginning of an HTML document, but then don not bother to write correct markup for the rest of it.

Heisenbug
It is an error, which disappears or alters when it is attempted to be identified by analogy to Heisenberg uncertainty principle in the quantum physics.

Jimmy
A generalized name for the clueless/new developer. The submitter at Stack Overflow writes:
We found as we were developing a framework component that required minimal knowledge of how it worked for the other developers. We would always phrase our questions as: "What if Jimmy forgets to update the attribute?"

This led to the term "Jimmy-proof" when referring to well designed framework code.

Higgs-Bugson
It is a hypothetical error, which existence is predicted on the basis of a small number (possibly) related to the log and vague anecdotal reports from the users, which is difficult to reproduce on the developer machine, because it is impossible to know whether it actually exists, and if there is something that caused it.

Here is a link to the Higgs boson - a hypothetical massive elementary particle that is predicted to exist by the Standard Model SM of particle physics.

Nopping
It is not napping, but simply zoning out. It comes from the assembly language instruction NOP, for No OPeration, which does nothing.

Other types of errors

Hindenbug
It is an error that causes the catastrophic data destruction.

Here is a link to Hindenburg dirigible, was destroyed during its attempt to dock with its mooring mast at the Lakehurst Naval Air Station.

Counterbug
It is a defensive move useful for code reviews. If someone reviewing your code presents you with a bug that is your fault, you counter with a counterbug: a bug caused by the reviewer.

Bloombug
This is the error that randomly generates money.
Perhaps, this is a link to the Bloomberg company.

Unicorny
An adjective to describe a feature that’s so early in the planning stages that it might as well be imaginary. This one comes from Rails Core Team member Yehuda Katz, who used it in his closing keynote at last year’s Windy City Rails to describe some of Rails’ upcoming features.

Barack Obama
It is a project management account that we assign the most aspirational tasks, the stuff we would really like to do, but we will probably never get an approval for it.

Loch Ness Monster bug
It is an error that will not repeat and only one person had seen it.

Baklava code
This is a code, which has too many layers.

Workaroundability
This is the feeling, when a cracked approach still can or cannot be cracked further.

Fear Driven Development
When project management adds more pressure, such as by firing a member of the team.

Common Law Feature
This is an error in the application, which has existed for so long that now it is a part of the expected functionality.

Here is a link to the "Common law", also it is known as case law or precedent.

Bicrement
Adding 2 to a variable.

Idioms that come from the food

Programmer fuel
It could be: Lemonade Mountain Dew, coffee and anything that fills you with caffeine.

Hot potato / Hot potatoes
It is a fun way to pronounce http:// and https://.

Send all the information about the client through the service authorization at «hot potatoes»: // company name.com/auth.

Cake
It depends on the context, usually it refers to some action on the noun. This noun should consist of one syllable for easy communication.

Banana banana banana
Placeholder text that indicates the documentation is in progress or yet to be completed. Mostly used because FxCop complains when a public function lacks documentation.
(Example: SVNStyleCop в C# или FxCop в C++).

/// 
/// banana banana banana
/// 
public CustomerValidationResponse Validate(CustomerValidationRequest request, booluseStrictValidation, bool throwIfSessionExpired)

Chunky salsa
This is a single critical error or bug that renders an entire system unusable, especially in a production environment.
It is based on the chunky salsa rule. Any situation that would reduce a character’s head to the consistency of chunky salsa dip is fatal, regardless of other rules.
The whole system turned chunky salsa after Bob's change to the login screen locked everyone out of their accounts.

Squizzle-giz
A horribly mispronounced version of the file extension .sql.gz
We made it up while setting up a server and looking for something easier/more fun to say than "dot ess que ell dot gee zee file" or "gzipped sequel file."

Hooker Code
Code that is problematic and causes application instability (application "goes down" often). Example: “Did the site go down again? Yeah, Jim must still have some hooker code in there”.

Reality 101 failure
The program (or more likely feature of a program) does exactly what was asked for, but when it’s deployed it turns out that the problem was misunderstood and the program is basically useless.

Hydra Code
A code that cannot be fixed. One fix causes two new bugs.
It should be rewritten.

Protoduction
This is a prototype that ends up in production.

Ninja Comments
It is also known as invisible comments, secret comments, or no comments.

Rubberducking
Sometimes, you just have to talk a problem out; for example: Someone put a rubber duck on the monitor, so he could talk to it, therefore, rubberducking is talking your way through a problem.

Databasically
Using a database to store information.
Example: "Hey, I'll put all of our customers into a Word document and then we can X." "No, we should do that databasically so that we can keep that list up to date."

The author of this idiom states that he named his company - “Databasically”.

Smurf Naming Convention
When almost every class has the same prefix. IE, when a user clicks on the button, a SmurfAccountView passes a SmurfAccountDTO to the SmurfAccountController. The SmurfID is used to fetch a SmurfOrderHistory which is passed to the SmurfHistoryMatch before forwarding to either SmurfHistoryReviewView or SmurfHistoryReportingView. If a SmurfErrorEvent occurs it is logged by SmurfErrorLogger to ${app}/smurf/log/smurf/smurflog.log.

Megamoth
MEGA MOnolithic meTHod. Usually, it stretches over two screens in height and often contained inside aGod Object (an object that knows or does too much). Megamoths of greater size than 2k LOC have been sighted. Beware of the megamoth!

apt-got and wgot
It designates the programs that were installed (on Unix) using the command apt-get and files that were downloaded using the command wget.
Examples: “I apt-got 100MB of updates this morning”. “Once this loop has wgot that file, it takes the md5 hash”.

Apache - Welcome back to Colombo

2012-02-24T22:03:00.000+05:30

Apache BarCamp Colombo - Sri Lanka 2012

Apache BarCamp hits Colombo!. This time we deliver a number of keynotes and practical sessions that gives a complete introduction to Apache Projects and how to contribute to them. IT professionals and IT students are welcome and it's free!!

Date : Sunday 26th/ 27th Feb 2012 - 9 AM

Venue :

Day 1

Date : Sunday 26th Feb 2012 - 9 AM Venue : Prof. VK Samaranayake auditorium , University of Colombo School of Computing.

Day 2

Date : Monday 27th Feb 2012 - 9 AM Venue : Virtusa new office auditorium , Dr Danister De Silva Mawatha,Colombo 09. ( Dematagoda)

Day - 1

Key Note speakers

Sanjiva Weerawarana
Ross Gardler

Nick Burch

Practical sessions

Find your way to Apache contribution.
Practical demonstration for Apache project developers. ( Debugging , Find and fixing issues and patching process)

Panel discussion

How to prepare how GSoC 2012 with Apache projects.

Day - 2

Era of BigData

Sessions on Apache Cassandra, Apache Hadoop and Apache Chemistry.
Panel discussion on BigData

Apache BarCamp is a dynamic get together open to the public. Like other unconferences, the schedule will be determined by the participants. This time for the benefit of students and new Apache contributers we have scheduled number of presentations during morning sessions of both days. In first day we target to have awareness sessions above Apache project contribution and community building. BigData related Apache projects is the main focus ares of second day but your are free to add your own topic or projects. Whether you're an open source hacker, student, accademic, commercial coder, hobbyist, interested amateur or any one else, we'd love to have you along! We hope that we'll allow different people to connect, share ideas, introduce projects and have fun, in the academic, open source and business sectors.

Further there is a GSoC experience sharing discussion scheduled to have during the first day so that GSoC 2012 participants can hear from past GSoC participants and GSoC mentors.

Sponsors :

WSO2, Virtusa UCSC, ASF

Change display's brightness on startup

2012-02-23T16:28:00.000+05:30

This is a sad story for me. My new Laptop hp Pavilion g4 has an ATI Radeon graphic chip set which don't have a working driver for Linux. So i'm facing lot problems in setting its brightness. As i work more than 20hrs in front of lap, i use minimum level of brightness on the LCD.

But unfortunately shortcut keys don't help me totally at the moment.So, i wanted to add a start up script to set the brightness on start up. here is how i did it. I think some one else may get it useful.

I'm going to use xbacklight tool for this... it can be simply installed using apt packager.

$ sudo apt-get install xbacklight

setBacklight.sh

 #!/bin/bash  
 case "$1" in  
 start)  
      echo "Setting brigtness to 10..."  
      xbacklight -set 10  
   ;;  
 stop)  
      echo "Setting brigtness to 100..."  
      xbacklight -set 100  
   ;;  
 restart)  
   $0 stop  
   $0 start  
   ;;  
 *)  
      xbacklight -set 10  
   echo "usage: $0 (start|stop|restart)"  
 ;;  
 esac  
 exit 0

You can check if it works by typing

$./setBacklight.sh restart

so this is a small shell script, but its a little different. This shell gets augment for the action as well.This shell is prepared to run as a init.d script on kernel start-up. To install this you need to to the following coding:

first copy the file to init.d run-level initialization folder

$ sudo cp setBacklight.sh /etc/init.d/

set permission to execute

$ sudo chmod +x /etc/init.d/setBacklight.sh

then add the script to other runlevels to be executed on system start:

$ sudo update-rc.d -f setBacklight.sh defaults

BUT.. unfortunately, my Linux Mint destro will reset display brightness on many occasions on system start up. so its no use of doing the above to change the brightness level for me.

Then i had to add a simpler command to Mint's Gnome start up settings to do my work.. ;(

xbacklight -set 10

Now everything works fine... :D

The 90th percentile: Storing User Preferences with Stripes and Spring 2...

2012-02-23T15:46:00.000+05:30

The 90th percentile: Storing User Preferences with Stripes and Spring 2...: "Keeping track of user customization is always messy: An instance must be kept alive for the whole user sessionIt will be read from the datab..."

Enable remote connection to mysql

2012-01-23T17:13:00.000+05:30

$ mysql -u root -p Enter password: mysql> use mysql_database_name; mysql> GRANT ALL ON *.* to root IDENTIFIED BY 'your-root-password';  mysql> FLUSH PRIVILEGES;

Start with apache httpd module development...

2011-12-12T14:25:00.000+05:30

Apache by name is the start of a giant in http server which is more than 50% of the web world. currently known as httpd, its on such useful because of its popularization architecture where anyone can do there own changes by just mounting a module.

So, today i'm going to demonstrate how to start with apache httpd dynamic module development with a hello world sample.

This tutorial is done on linux Mint destro. But any linux version will be no problem. Developing apache modules for windows is pretty straight forward, but need to prepare some tools which is not directly downloadable. The tool used is c/c++ compiler and apxs[APache eXtenSion] tool. apxs for windows is a purl module, and it need to have some configurations. But there wont be any change on application source of on development procedure. For the moment i'll continue for linux and will hope to continue windows instructions later.

Required components:
Apache httpd server[remember its not tomcat]
Apache Extension installed
gcc/g++ compiler
root access on mounting module to httpd and for restarting server

Steps
1.install apache2 and verify its running...

$ sudo apt-get install apache2

2.install apache extension tool

sudo apt-get install apache2-threaded-dev

this will install required apache libs and includes. apache portable runtime[apr] may be install with apache server installation. so no need to bother on those.

3.Start development now

apache portable runtime is a world class c/c++ library for save coding on a portable platform with light weight, but high performance. apache httpd server is the main project which was done using apr. so all the developments we are doing here is on top of apr. we only use major c/c++ libraries here.

If you have experience on linux kernel development, as you know there is a separate/dedicated set of libraries/include intended for kernel developments. Ideal situations here as well. instead of printf on std , we used printk in kernel modules. Here we use ap_rprintf. apache httpd modules are also very similar on functionality to linux kernel modules. You'll get to know those greatly.

There are two necessary includes in the module

#include "httpd.h"
#include "http_config.h"

apache module is identified by httpd with a well defined data structure: AP_MODULE_DECLARE_DATA

there are major difference from apache 1.3x to 2.xx versions of httpd. So please be alert on which version you are using.here i'm doing with the latest[updated for version 1.4 on Feb 2012].

module AP_MODULE_DECLARE_DATA foo_module = {
STANDARD20_MODULE_STUFF,
foo_config_perdir_create, /* create per-dir config structures */
foo_config_perdir_merge, /* merge per-dir config structures */
foo_config_server_create, /* create per-server config structures */
foo_config_server_merge, /* merge per-server config structures */
foo_config_cmds, /* table of configuration directives */
foo_register_hooks /* register hooks */
};

The most important of here is the "register hooks" other config's are kept NULL on this sample.
This hook is the join between httpd server and the module. This hook is created on server start. Actually speaking, this is a fork pipe name or a socket pipe in deep.

All requests to the httpd server will be mirrored to this hook and its the responsible of this hook to use a handler to execute the http request. So, lets see how we achieve this.

module AP_MODULE_DECLARE_DATA apache_test_module =
{
STANDARD20_MODULE_STUFF,
NULL, /* per-directory config creator */
NULL, /* directory config merger */
NULL, /* server config creator */
NULL, /* server config merger */
NULL, /* command table */
apache_test_register_hook, /* request processing*/
};

This hook has a definition of
static void

apache_test_register_hook

(apr_pool_t *p) ;

What we have to do is to define a function to be handled by the requests coming from apache httpd pool.
Within this function lets define a separate handler function to look better coding.

static int ap_hook_http_req_handler(request_rec *r) ;

So, here is the actual hook function definition:

static void apache_test_register_hook(apr_pool_t *p)
{
ap_hook_handler( apache_test_handler, NULL, NULL, APR_HOOK_MIDDLE);
}

What we have done now are, we have asked httpd to send us http sequests by sending a hook, and within the hook we have set a handler function to get the http request parameters.
Then what we have to do is to do the actual work we are all wanted to do from the start. To do something with the http requests. For example, lets say we want to send our own html tags to the browser from our module. What we have to do is to return the request with a proper html tag and with status 200k http response code. Now lets see how to achieve this.

static int apache_test_handler(request_rec *r) ;

so we define the actual handler function.

 #include "httpd.h"   
 #include "http_config.h"   
 static int apache_test_handler(request_rec *r)   
 {  
     if (strcmp(r->handler, "apache_test_module"))  
     {  
         return DECLINED;   
     }  
     ap_set_content_type(r, "text/html");   
     ap_rputs("<HTML>\n", r);  
     ap_rputs("\t<HEAD>\n", r);  
     ap_rputs("\t\t<TITLE>\n\t\t\tApache Test Module\n\t\t</TITLE>\n", r);  
     ap_rputs("\t</HEAD>\n\n", r);  
     ap_rputs("<H1>Hello Idiots....</H1>\n", r);  
     ap_rprintf(r, "Engineers are inside too..!!! <br>");  
     ap_rprintf(r, "<a href=\"http://blog.friendly.lk\">back to blog</a>\n");  
     ap_rputs("</BODY></HTML>\n" ,r);   
     return OK;   
 }   
 static void apache_test_register_hook(apr_pool_t *p)   
 {   
     ap_hook_handler(apache_test_handler, NULL, NULL, APR_HOOK_MIDDLE);   
 }   
 module AP_MODULE_DECLARE_DATA apache_test_module =   
 {   
     STANDARD20_MODULE_STUFF,   
     NULL, /* per-directory config creator */   
     NULL, /* directory config merger */   
     NULL, /* server config creator */   
     NULL, /* server config merger */   
     NULL, /* command table */   
     apache_test_register_hook, /* other request processing hooks */   
 };

here at the first if() we check whether the request is from url http://localhost/apache_test_module otherwise we avoid processing.

so.. here is the final source save this in a file apache_test_module.c

and now its time to compile and install this module on apache server.

fist cd to the place where source apache_test_module.c is. then do the following with root privileged.

$ sudo apxs2 -ci apache_test_module.c

Ok.. now the development part is done.But still, how the server will identify and forward requests to our module? for that, we need to configure our module in httpd.conf configuration file located at /etc/apache2/httpd.conf

$ sudo gedit /etc/apache2/httpd.conf

add the following two two configurations on the fly.

LoadModule apache_test_module /usr/lib/apache2/modules/apache_test_module.so

SetHandler apache_test_module

the first tells httpd to load a new module called apache_test_module.so with the handler named apache_test_module.

the second says httpd request path handler to forwaard /apache_test_module URLs to above handler.

now its time to restart apache2 and check how it works...

$ sudo /etc/init.d/apache2 restart

then go to http://localhost/apache_test_module from your browser....

give me some comments on your results!!!!

Thanks!!!

On the way for my own thread pool [Semaphore] for multi-threaded applications

2011-12-12T10:23:00.000+05:30

In Linux environment, there is a lack of ready made Database connection pool object or even a easily usable connection object invokees. So, i supposed to write my own implementations for the subject. But still there are some pretty good libraries to ease the implementations [eg: boost C++ lib]. But i thought to continue with standard way. Still this code is under development. The following code is still usable, but with lot of cavities. I'v implemented mutex mode here. But need to implement Semaphore and avoid Blocked Waiting. That require to implement pThread. Your ideas are always welcome.

 /**get a new connection from the pool*/  
 sql::Connection* DBConnector::getConnection(void)  
 {  
  bool gotaconnection = false;  
  for(;!gotaconnection;)  
  {  
  sql::Connection* tmpConnection = NULL;  
  /*if lock is free, lock it and go inside*/  
  if(DBConnector::isFreeThenLock())  
  {  
   /*if there are free connections in the pool go and get it then free the lock and go*/  
   if(freeConnectionList->size() > 0)  
   {  
   tmpConnection = freeConnectionList->front();  
   this->freeConnectionList->pop_front();  
   this->usedConnectionList->push_back(tmpConnection);  
   TEST_LOGGER(SLOGGER_INFO_LOG_LEVEL, "GETCONNECTION : ", (char*)tmpConnection);  
   DBConnector::free();  
   gotaconnection = true;  
   return tmpConnection;  
   }else  
   {/*check if there can create more connections*/  
   TEST_LOGGER(SLOGGER_INFO_LOG_LEVEL, "CURRENT NUM OF CONNECTIONS : ", (freeConnectionList->size() + usedConnectionList->size()));  
   if((freeConnectionList->size() + usedConnectionList->size()) < (maxConnections))  
   {  
    bool successCreation = false;  
    for(;!successCreation;){  
    try{  
    TEST_LOGGER(SLOGGER_INFO_LOG_LEVEL, "CREATING MORE CONNECTIONS : ", "");  
     const std::string tmpUrl = std::string("tcp://").append(this->hostName).append(":").append(this->port);  
     tmpConnection = this->driver->connect(tmpUrl.c_str() , this->userName.c_str() , this->pswd.c_str());  
     tmpConnection->setSchema(this->schemaName.c_str());  
     tmpConnection->setAutoCommit(true);  
     this->usedConnectionList->push_back(tmpConnection);  
     TEST_LOGGER(SLOGGER_DEBUG_LOG_LEVEL, "CREATE CONNECTION : ", (char*)tmpConnection);  
     TEST_LOGGER(SLOGGER_INFO_LOG_LEVEL, "GETCONNECTION : ", (char*)tmpConnection);  
     successCreation = true;  
     gotaconnection = true;  
     DBConnector::free();  
     return tmpConnection;  
    }catch(sql::SQLException &e)  
    {  
     TEST_LOGGER(SLOGGER_FATAL_LOG_LEVEL, "ERROR RECREATING CONNECTIONS : ", e.what());  
     successCreation = false;  
     continue;  
    }  
    }  
   }else  
   {  
    TEST_LOGGER(SLOGGER_ERROR_LOG_LEVEL, "CAN'T ALLOCATE MORE CONNECTIONS, RETURNNING NULL : ", "");  
    DBConnector::free();  
    gotaconnection = true;  
    return NULL;  
   }  
   }  
  }  
  TEST_LOGGER(SLOGGER_ERROR_LOG_LEVEL, "COULD NOT GET A CONNECTIONS, WAIT AND RETRY: ", "");  
  DBConnector::free();  
  //Sleep(1);  
  }  
  return NULL;  
 }  
 Here is the sub functions that are on development to make ease the coding:  
 /**release a connection back to the pool*/  
 void DBConnector::releaseConnection(sql::Connection* connToRelease)  
 {  
  if(DBConnector::isFreeThenLock())  
  this->usedConnectionList->remove(connToRelease);  
  if(connToRelease!=NULL && !connToRelease->isClosed()){  
  this->freeConnectionList->push_back(connToRelease);  
  TEST_LOGGER(SLOGGER_INFO_LOG_LEVEL, "RELEASECONNECTION: ", (char*)connToRelease);  
  }else{  
  TEST_LOGGER(SLOGGER_FATAL_LOG_LEVEL, "DISCARD CONNECTION: ", (char*)connToRelease);  
  }  
  DBConnector::free();  
 }  
 /*check if the pool object is free and lock it its free*/  
 bool DBConnector::isFree(void)  
 {  
  return DBConnector::syncLock == 0 ? true : false;  
 }  
 /*check if the pool object is free to use for concurrent access*/  
 bool DBConnector::isFreeThenLock(void)  
 {  
  if(DBConnector::syncLock == 0)  
  {  
  DBConnector::syncLock = 1;  
  TEST_LOGGER(SLOGGER_INFO_LOG_LEVEL, "LOCKED: ", "");  
  return true;  
  }  
  return false;  
 }  
 /*release pool lock*/  
 bool DBConnector::free(void)  
 {  
  if(DBConnector::syncLock != 0)  
  {  
  TEST_LOGGER(SLOGGER_INFO_LOG_LEVEL, "FREED: ", "");  
  DBConnector::syncLock = 0;  
  return true;  
  }  
  DBConnector::syncLock = 1;  
  return false;  
 }  
 bool DBConnector::error(void)  
 {  
  DBConnector::syncLock = -1;  
  TEST_LOGGER(SLOGGER_ERROR_LOG_LEVEL, "ERROR: ", "");  
  return false;  
 }

Useful Abstract Methods

2011-11-24T16:32:00.000+05:30

This is somewhat older and useful set of code, but i can't remember where it was... may be when i was using ehCache for data pre-loading in says at MIT.

/**

    * Get Object Type  
    *  
    * @return  
    */  
   public Class getObjectType() {  
     return (this != null ? this.getClass() : CacheManagerEventListener.class);  
   }

C# Simple drag and drop example

2011-09-09T10:01:00.000+05:30

Sometimes back i wanted to create a XML design tool to development with some GUI based tool kit. But unfortunately i had no time to continue with the project.

I tried with some available code from internet to test the requirements..... just a copy past is here, till re-start the project sooner.

C# Simple drag and drop example:

// Form load event or a similar place private void Form_Load(object sender, EventArgs e)
{
    // Enable drag and drop for this form // (this can also be applied to any controls) this.AllowDrop = true;
    // Add event handlers for the drag & drop functionality this.DragEnter += new DragEventHandler(Form_DragEnter);
    this.DragDrop += new DragEventHandler(Form_DragDrop);
}
// This event occurs when the user drags over the form with // the mouse during a drag drop operation void Form_DragEnter(object sender, DragEventArgs e)
{
    // Check if the Dataformat of the data can be accepted // (we only accept file drops from Explorer, etc.) if (e.Data.GetDataPresent(DataFormats.FileDrop)) e.Effect = DragDropEffects.Copy;
    // Okay else e.Effect = DragDropEffects.None;
    // Unknown data, ignore it
}
// Occurs when the user releases the mouse over the drop target void Form_DragDrop(object sender, DragEventArgs e)
{
    // Extract the data from the DataObject-Container into a string list string[] FileList = (string[])e.Data.GetData(DataFormats.FileDrop, false);
    // Do something with the data...  // For example add all files into a simple label control: foreach (string File in FileList) this.label.Text += File + "\n";
}

SQL joins graphically simplified...

2011-07-08T10:13:00.000+05:30

SQL[structured query language] is the language to get data from a DB. It let you retrieve data from a simple "select *" to many customized ways. "JOIN" is the keyword to retrieve data from multiple tables with a given relationship "ON".

There are few more keywords used with JOIN, and some are optional. ex: INNER, OUTER,LEFT,RIGHT,FULL,CROSS,... those keywords depends on the DB you are using.

As given early JOIN give us the opportunity to retrieve rows which are related on two tables. So those could be able to show in a Cartesian Venn diagram. So i have created two sample tables and added sample data to those. lets see how this can be simulated.

First lets create sample tables:

CREATE TABLE tblleft ( id_customer int(10), customer_name varchar(10) ) ENGINE=InnoDB DEFAULT CHARSET=latin1;
insert into tblleft (id_customer, customer_name) values (1, 'amara');
insert into tblleft (id_customer, customer_name) values (2, 'dasun');
insert into tblleft (id_customer, customer_name) values (3, 'saman');
insert into tblleft (id_customer, customer_name) values (4, 'nimal');
insert into tblleft (id_customer, customer_name) values (5, 'kasun');

CREATE TABLE tblright ( id_order int NOT NULL AUTO_INCREMENT, id_customer int, equipment varchar(10) DEFAULT '_', PRIMARY KEY (id_order) ) ENGINE=InnoDB DEFAULT CHARSET=latin1;

insert into tblright (id_order, id_customer, equipment) values (1, 1, 'food');

insert into tblright (id_order, id_customer, equipment) values (2, 2, 'car');

insert into tblright (id_order, id_customer, equipment) values (3, 6, 'computer');

insert into tblright (id_order, id_customer, equipment) values (4, 7, 'fan');

insert into tblright (id_order, id_customer, equipment) values (5, 3, 'mobile');

First lets do the simple join and retrieve data which are common with id_customer in the two tables

SELECT

FROM

tblleft l

JOIN tblright r

l.id_customer=r.id_customer;

hers is the results:

SELECT

FROM

tblleft l

LEFT OUTER JOIN tblright r

l.id_customer=r.id_customer;

SELECT

FROM

tblleft l

RIGHT OUTER JOIN tblright r

l.id_customer=r.id_customer;

SELECT

FROM

tblleft l

LEFT OUTER JOIN tblright r

l.id_customer=r.id_customer

WHERE

r.id_order IS NULL;

SELECT

FROM

tblleft l

RIGHT OUTER JOIN tblright r

l.id_customer=r.id_customer

WHERE

l.id_customer IS NULL;

SELECT

FROM

tblleft l

LEFT OUTER JOIN tblright r

l.id_customer=r.id_customer

UNION

SELECT

FROM

tblleft l

RIGHT OUTER JOIN tblright r

l.id_customer=r.id_customer;

SELECT

FROM

tblleft l

LEFT OUTER JOIN tblright r

l.id_customer=r.id_customer

WHERE

r.id_order IS NULL

UNION

SELECT

FROM

tblleft l

RIGHT OUTER JOIN tblright r

l.id_customer=r.id_customer

WHERE

l.id_customer IS NULL;

8:Cross join will provide the Cartesian product , but it cant be drawn by a Venn diagram.

SELECT

FROM

tblleft l

JOIN tblright r;

SELECT

FROM

tblleft l ,

tblright r;

I hope you get some idea on how those result sets are described with Venn diagrams.

Thank you!

Prevent XSS and request forgery and other common attack patterns | [: GaB :]

2011-07-06T12:32:00.000+05:30

It looks like two-third of the attacks are based on three vectors:

1. SQL injection (25%)

$id="1;DROP TABLE users"; mysql_query("SELECT * FROM bars WHERE id=".$id); It is deeply shocking how many "developers" still don't get the message not to execute SQL commands forged from user input. Or at least, why are they still employed? This attack would be the most simple to prevent. You just always have to *escape* strings which are parameters of the sql query coming in as request parameters. If in doubt, what do I mean by that, simply escape *all* parameters of a query. Or better use queries parameterized as "SELECT ... WHERE id=? AND type=?"-s, your language must have a way to pass the values safely afterwards.
But stop, why in the world are these guys still writing any SQL queries in the first place?! Because script kiddies don't know what a persistence framework is. Stop handcrafting CRUDDAOs.

2. Cross-site scripting a.k.a. XSS (17%)

Rule of thumb: always check. If you use any output mechanism or view, check whether it escapes or not. If not, it is *your job* to do so! (Error messages printing also the invalid value are the simplest to overlook.)

* escapes by default.

* ${id} never escape by default. This is one of the most pithiest design decision in JSTL/EL. It is insecure by default. But of course you have the option to turn on security. Thank you very much. I understand the need for backward compatibility, but this is the kind of design problems which can be solved. Why not add an option to change the default behavior, and add fn:unEscapeXml() ?

<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %> ${fn:escapeXml(id)}

Plain EL expressions to produce output is pure evil.

* The output tags of your framework of choice is the most important to test. Never assume you already know it. In Spring 2.0 escaping in the form:input and form:errors tags were optional and off by default. In 2.5, it was switched to on by default in the documentation. But form:errors tag continued to print out unescaped output. In 3.0 everything seems to be fine by default in both.

Just to improve your chances always add this to your root context:

     defaultHtmlEscape     true

3. Authentication and authorization (14%)

I guess mostly this happens by plain simply ignoring security logic. Most likely to happen when refactoring and ignoring to adopt security logic to the new business logic or domain structure. Those three should be independent by design. AOP or a security framework is a good candidate for separating the security concerns.
If you are not in control of the server side issues, use discovery tools like PhpSecInfo.

++1 Cross site request forgery a.k.a. CSRF and XSRF

Only 2% of the identified attacks fall into this category. But I also saw a lot of plain simply wrong attempts to fix this issue. This also shows how non-trivial it is for the average programmer to safeguard against this kind of attacks. It feels like many sites are vulnerable but not exploited yet.
To check the ingenuity of requests, first one must ensure, that GET requests are never changing state of the domain. (Trivial but not for everyone.)
Second, to always check POST requests' referer header values: they must match yours. This is sufficient for protection against XSRF, but has limitations.
Mostly suggested are tokens, a hidden field in every POST with a random variable identifying genuine requests (e.g. hash of the SESSIONID). The problem is, that every browser has a way to hack around it. You have to generate a new random token for each request to be used to fully safeguard yourself.
Alternatively you can change URLs dynamically (the token becomes part of the URL): for example you can use Spring's @PathVariable annotation bound to a @RequestParam("/action/{nextToken}").

Favorite Text circle on console

2011-04-26T16:05:00.001+05:30

Here is a small code snippets for displaying famous charactor circle on the console.... you may enjoy it!!!

private String circle() {

   if ((System.currentTimeMillis() - startTime) < 100) {
   startTime = System.currentTimeMillis();
   return "\r" + current + "\t";
   }

   if (current == '|') {
   current = '/';
   } else if (current == '/') {
   current = '-';
   } else if (current == '-') {
   current = '\\';
   } else {
   current = '|';
   }
   return "\r" + current + "\t";
   }

deploying war file on Weblogic server by using ant scripts

2011-03-22T16:41:00.000+05:30

Auto deploying war file on Weblogic server by using ant scripts

 server="t3://${weblogic.adminhost}:${weblogic.adminport}"  
 classpath="${weblogic.classpath}"  
 username="${weblogic.user}"  
 password="${weblogic.password}"  
 component="${app.name}:${app.name}"  
 debug="true";  
 classname="weblogic.ant.taskdefs.management.WLDeploy"  
 classpath="C:/bea/weblogic81/server/lib/weblogic.jar"  
 name="wldeploy";  
 debug="true" password="tropicAl"  
 source="${build}/test.war"  
 targets="fwmgb-ms01" user="system" verbose="true";   
 classpathref="weblogic.classpath" ;  
 user="${weblogic.user}" password="${weblogic.password}"  
 adminurl="t3://${weblogic.adminhost}:${weblogic.adminport}" source="dist/${app.name.war}"  
 action="deploy";  
 message="Successfully Deployed @http://${weblogic.adminhost}:${weblogic.adminport}/${app.name.war}"  
 adminurl="t3://${weblogic.adminhost}:${weblogic.adminport}" name="${app.name.war}"  
 action="undeploy" /&gt;  
 adminurl="t3://${weblogic.adminhost}:${weblogic.adminport}" name="${app.name.war}"  
 action="redeploy" /&gt;  
 c:\NewClearProject\MITDevelopmentDeployment\eclipseWorksPlace\MyWebApp&gt;java w  
 eblogic.Deployer -verbose -noexit -name MyWebApp -adminurl t3://localhost:700  
 1 -user newclear -password mit12345 -undeploy  
 C:\Oracle\Middleware\wlserver_10.3\server\bin&gt;java weblogic.Deployer -verbose -n  
 oexit -source C:\NewClearProject\MITDevelopmentDeployment\eclipseWorksPlace\NewC  
 learWeb\dist\MyWebApp.war -name MyWebApp -adminurl t3://localhost:7001 -us  
 er newclear -password mit12345 -deploy  
 weblogic.Deployer invoked with options: -verbose -noexit -source C:\NewClearPro  
 ject\MITDevelopmentDeployment\eclipseWorksPlace\MyWebApp\dist\MyWebApp.war  
  -name MyWebApp -adminurl t3://localhost:7001 -user newclear -deploy

Lakdasun Trip Reports Archive » Kirigalpoththa Hike on 1st of January 2011

2011-01-11T22:17:00.000+05:30

Lakdasun Trip Reports Archive » Kirigalpoththa Hike on 1st of January 2011

install Pulse- Audio Equalizer on Ubuntu 10.10

2011-01-09T20:56:00.000+05:30

sudo add-apt-repository ppa:nilarimogard/webupd8
sudo apt-get update;
sudo apt-get install pulseaudio-equalizer

Forwarding apache requests to Tomcat servlet container

2010-12-20T14:09:00.075+05:30

Most web applications todays are using favorite Apache web server for its proven architecture and free apache license.
Tomcat is same as a very famous servlet container or java application server.
Although tomcat itself can be access as a simple web server, for production environments it may lack some features like load-balancing, redundancy, etc.

So the best way to use is to integrate those two application, and finally its a great combination for enterprise applications for excess performance and ease of maintenance.

The theory behind is to use a middle tier connector called mod_jk.so module which communicate using AJP(Apache JSer Protocol ) version 1.3, best of currently available stable version.See the following figure for graphical view.

Here in this small steps guide i configure an Apache2 to a single instance of Tomcat6.Any comments and improvements are welcome at the end.

installations:

install apache2;Web server who listen on port 80
sudo apt-get install apache2

install tomcat6 and its applications>Application server/Web Container who translate application code in to results listen on port 8080 by default

sudo apt-get install tomcat6
sudo apt-get install tomcat6-common
sudo apt-get install tomcat6-examples
sudo apt-get install tomcat6-admin
sudo apt-get install tomcat6-docs
sudo apt-get install tomcat6-user

install libapache2-mod-jk>Connector module to forward web request to redirect in to tomcat's port 8009,8005 etc
sudo apt-get install libapache2-mod-jk

Configurations:

ask Apache to forward default pages to ajp13_worker through installed jk module by adding following two lines to this file by 'gedit /etc/apache2/sites-enabled/000-default'
<.....>
ServerAdmin chand@engineering.com
JkMount / ajp13_worker JkMount /* ajp13_worker

....... file continues................

to make above to work, verify that following line is there on '/etc/apache2/mods-enabled/jk.load'
LoadModule jk_module /usr/lib/apache2/modules/mod_jk.so

Now you have to tell jk_mod to find its configuration file path and how it should log errors and other informations.So add the following lines after LoadModule as above

JkWorkersFile /etc/libapache2-mod-jk/workers.properties
JkLogFile /var/log/apache2/mod_jk.log
JkShmFile /var/log/apache2/mod_jk.shm
JkLogLevel info
JkLogStampFormat "[%a %b %d %H:%M:%S %Y] "

Now Apache will forward the requests to mod_jk module.Now its time to configure mod_jk to forward those request to Tomcat.So goto its configuration file as you defined on the above:

/etc/libapache2-mod-jk/workers.properties

Here you have to explicitly and correctly define 3 main parameters for jk module:

Tomcat Home
Java Home
Exact parameters of the Worker(ex: ajp13_worker )

in my server its with following configurations.But you can goto relevant folders and find out what are the available folders/java VMs you can configure for.

workers.tomcat_home=/usr/share/tomcat6

workers.java_home=/usr/lib/jvm/java-6-openjdk

worker.list=ajp13_worker

worker.ajp13_worker.port=8009
worker.ajp13_worker.host=localhost
worker.ajp13_worker.type=ajp13
worker.loadbalancer.balance_workers=ajp13_worker

OK! now jk module knows how to forward requests to port 8009, then we have to configure someone to listen on port 8009, and its tomcat.

Goto /etc/tomcat6/server.xml
By default tomcat don't listen to ajp13 protocol on port 8009, only on 8080 fot http requests.
you can uncomment the following line

'< Connector port="8009" protocol="AJP/1.3" redirectPort="8443" / >'

Now to all those changes to take effect you have to restart both services, but tomcat6 1st and then apache.

When you browse to http://localhost you must be shown with tomcat's default page as you seen by http://localhost:8080

if both are same... now all your web requests on port 80 that were listen by apache web server are forwarding to Tomcat Servlet container.

In the same way as above, you can configure apache to request PHP sites as well.Lets see it in some other article.

Good Luck!!!!

Enable Packet forwarding on for Internet Connection Sharing on Linux

2010-12-19T08:26:00.001+05:30

Enable NATting for internet connection:

ppp0-internet connected port

add on startup or to /etc/init.d/rc.local

sudo iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE

Enable Packet accep for incoming requests:

Edit following file and change/uncomment following line to enable packet forwarding for incoming request packets.

/etc/sysctl.conf: net.ipv4.ip_forward = 1

to get control over the packet forwarding, we can forward all NATed packets to a local proxy server

to disable direct packet forwarding, change
/etc/sysctl.conf: net.ipv4.ip_forward = 0

then add an additional route;
i don't know whether the sequence of following will affect, just check you guys ans let me know....
:-)

iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 80 -j REDIRECT --to-port 3128

iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE

Approach to Multi Threaded Socket Communication

2010-12-04T06:48:00.001+05:30

On this article i will introduce with socket connection on single server multiple clients,Single client multiple messages(transaction based continuous connection),Multiple client multiple transaction (per connection). I will proceed with two methods of threading (extend Thread and implement Runnable).

Also at the requirement, i'll explain the use of synchronized shared objects and serialized data objects.

This article is the extend of basic-socket-programming article on www.chandpriyankara.tk/www.estudents.lk

single server multiple clients

This scenario is the most widely used socket communication in general.For example web servers.Many clients connects to the server requesting some data.The 3way TCP/IP handshake will initiate and identifies the two parties.Here, as regular, client who needs data wants to start the connection.Server or the data source must be up and running, waiting for a connection request form a client for a particular local port number(eg:80).Client will connect to the server,and the server will start a new thread in order to serve the clients request and transfer context to that thread.The master/main thread will resume and will stand by for another request from some other client(may be the same client).The created thread will process independently and serve data to the client.

As soon as the data is served, the connection will be closed.So, same client for some other data, wants to initiate another connection.This way the server is stateless of the clients, or all requests/connections are totally independent with others.

To serve independantly, the server must have a multi-thread application while client may very.

Basic Socket Programming

2010-12-02T23:00:00.000+05:30

Socket programming a is data exchange method used in electrical systems, specially within two or more(even itself) systems within a network reachability.

Inter networked computers are widely using this method to transfer various data and information with remote systems.Socket programming, just up on the TCP layer, provides a mean of interprocess communication. In order to successful completion of the socket communication, all TCP/IP and lower layers need to be fully and correctly in functional.

As this articel involved in explaining simple simple data transfer implementation we will limit the limit our scope into computer application programming with its simplest form.

In order to exchange data within systems, there need to be at least two parties, who Requires some data to transfer to a Listener party. Who request to send data, or the one who initiate to connect is called the client. Who is ready to listen, and waiting for some one else to initiate a request is called server.

In order to start the communication, the server need to be ready and on listening state. So, at a glance lets look how to make a server and make it to listen for a client request.

Most of the languages provides easy way to create this object, while here i go with java.

A socket connection consists of a application layer's port and internet/IP layer's IP address.IP address belongs to the OS. So our application have no control over it.But we can use any[1-65535 (below 1024 need root access)] port[to listen].

According to the requirements we can use several implementation techniques to handle data transfered between a socket connection.It may be uni-directional, client server, multi thread server, transaction based,etc.

We may first go through basic implementation of a TCP listener or a listener socket.

For this article i use JDK 1.6 with NetBeans 6.9 on Ubunut 10.10 but codings are same for any java implementation (for same JDK).

File->New Project->Java(Categories)||Java Application(Application)->Project Name||Create Main Class->Finish

import Server Socket object.

import java.net.ServerSocket;

try {

ServerSocket serverSocket = new ServerSocket(2000, 1);

Socket clientSocket = serverSocket.accept();

//this part of the code will handle the business logic

} catch (IOException ex){

Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);

}

Server socket will reserve a port number for the application process, which waits for a connection request from another process[local/remote].

'serverSocket.accept()' will return a reference ('clientSocket') to the local end socket for the newly established data pipe.It can be used when ever the process wants to send or receive data back and forth.Initially the server process will run up to above line and hang there until a remote client send a request to connect.

Prepare another java project as above and implement a client socket:

Socket socket = new Socket("localhost", 2000);
//business logic comes here
} catch (UnknownHostException unknownHostException) {

System.out.println("Host no Found: " + unknownHostException.toString());

} catch (IOException iOExceptionx) {

System.out.println("Connection Failed: " + iOExceptionx.toString());

}

Now, the connection can be established.But there is no use till we use it to send and receive data through the connection.So, create read and write iostreams on both socket ends.

on Server side:

InputStream receiveData = clientSocket.getInputStream();

OutputStream sendData = clientSocket.getOutputStream();

on Client side:

InputStream receiveData = socket.getInputStream();

OutputStream sendData = socket.getOutputStream();

Now we can send and receive data through data channel between two processes.

Complete Code for Server:

package javaapplication1;
import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.net.ServerSocket;

import java.net.Socket;
/**

* @author chand

public class Main {
/**

public static void main(String[] args) {

try {

// TODO code application logic here

int maxDataSize = 100;

String messageToSend = "messageFromServer";

String receivedMessageFromClient = "";

ServerSocket serverSocket = new ServerSocket(2000, 1);

Socket clientSocket = serverSocket.accept();

InputStream receiveData = clientSocket.getInputStream();

OutputStream sendData = clientSocket.getOutputStream();

byte[] data = new byte[maxDataSize];

int receivedMessageLength = receiveData.read(data);

receivedMessageFromClient = new String(data);

System.out.println("\nReceivedMessageFromClient: " + receivedMessageFromClient + " messageLength: " + receivedMessageLength);

data = messageToSend.getBytes();

sendData.write(data);

} catch (IOException iOExceptionx) {

System.out.println("Connection Failed: " + iOExceptionx.toString()); }

}

Complete Code for Client:

kage javaapplication2;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.net.Socket;

import java.net.UnknownHostException;

/**

* @author chand

public class Main {

/**

* @param args the command line arguments

public static void main(String[] args) {

try {

// TODO code application logic here

int maxDataSize = 100;

String messageToSend = "messageFromClient";

String receivedMessageFromServer = "";

Socket socket = new Socket("localhost", 2000);

InputStream receiveData = socket.getInputStream();

OutputStream sendData = socket.getOutputStream();

byte[] data = new byte[maxDataSize];

//write and read events has been interchanged to avoid dead locks

data = messageToSend.getBytes();

sendData.write(data);

int receivedMessageLength = receiveData.read(data);

receivedMessageFromServer = new String(data);

System.out.println("\nReceivedMessageFromServer: " + receivedMessageFromServer

+ " messageLength: " + receivedMessageLength);

} catch (UnknownHostException unknownHostException) {

System.out.println("Host no Found: " + unknownHostException.toString());

} catch (IOException iOExceptionx) {

System.out.println("Connection Failed: " + iOExceptionx.toString());

}

Steps for creating blazds communication

2010-11-02T14:53:00.002+05:30

Steps for creating blazds communication
1.web.xml need to hava servlet mapping for servlet engine
[

flex.messaging.HttpFlexSession

MessageBrokerServlet

flex.messaging.MessageBrokerServlet

services.configuration.file

/WEB-INF/flex/services-config.xml

RDSDispatchServlet

flex.rds.server.servlet.FrontEndServlet

useAppserverSecurity

false

RDSDispatchServlet

/CFIDE/main/ide.cfm

MessageBrokerServlet

/messagebroker/*

]

2.services-config.xml need to have initalized with services + defauld channel + other regular values
[

server="Tomcat" />

class="mx.messaging.channels.AMFChannel">

url="http://{server.name}:{server.port}/{context.root}/messagebroker/amf"
class="flex.messaging.endpoints.AMFEndpoint" />

class="mx.messaging.channels.SecureAMFChannel">

url="https://{server.name}:{server.port}/{context.root}/messagebroker/amfsecure"
class="flex.messaging.endpoints.SecureAMFEndpoint" />

false

class="mx.messaging.channels.AMFChannel">

url="http://{server.name}:{server.port}/{context.root}/messagebroker/amfpolling"
class="flex.messaging.endpoints.AMFEndpoint" />

false

class="mx.messaging.channels.HTTPChannel">

url="http://{server.name}:{server.port}/{context.root}/messagebroker/http"
class="flex.messaging.endpoints.HTTPEndpoint" />

class="mx.messaging.channels.SecureHTTPChannel">

url="https://{server.name}:{server.port}/{context.root}/messagebroker/httpsecure"
class="flex.messaging.endpoints.SecureHTTPEndpoint" />

false

[BlazeDS]
true
true
true
true

Endpoint.*
Service.*
Configuration

true

{context.root}/WEB-INF/flex/services-config.xml

{context.root}/WEB-INF/flex/proxy-config.xml

{context.root}/WEB-INF/flex/remoting-config.xml

{context.root}/WEB-INF/flex/messaging-config.xml

{context.root}/WEB-INF/flex/data-management-config.xml

{context.root}/WEB-INF/web.xml

]

3.remoting-config.xml need to have defined adaptors + distinations +
[

class="flex.messaging.services.remoting.adapters.JavaAdapter"
default="true" />

class="flex.messaging.services.messaging.adapters.ActionScriptAdapter" />

class="flex.messaging.services.messaging.adapters.JMSAdapter" />

hello.Hello

]

4.Define the remote object at the action script/application .mxml file

5. Define result handler and fault handler methods

[ private function faultHandler(fault:FaultEvent):void {
result_text.text = "code:\n" + fault.fault.faultCode + "\n\nMessage:\n" + fault.fault.faultString + "\n\nDetail:\n" + fault.fault.faultDetail;
}

private function resultHandler(evt:ResultEvent):void {
var hh:valueObjects.RemoteObject = (valueObjects.RemoteObject)(evt.message.body);
//result_text.text = evt.message.body.toString();
result_text.text = hh.address;
result_text.text += "\n" + hh.id;
result_text.text += "\n" +hh.name;
}
]

6.Invoke functions from a user custom event object

package hello;

public class Hello {
RemoteObject rm ;
   public RemoteObject sayHello() {
   return this.rm;
   }

   public void saveHello(RemoteObject rmOb) {
   this.rm = rmOb;
   }
   public Hello() {
rm = new RemoteObject();
rm.setId(56);
rm.setAddress("79-A");
rm.setName("chand");
}
}

package hello;

import java.io.Serializable;

public class RemoteObject implements Serializable {

private static final long serialVersionUID = 4355646632118270964L;
private int id = 0;
private String name = "";
private String address = "";

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public String getAddress() {
return address;
}

public void setAddress(String address) {
this.address = address;
}
}

RIA With Flex & Java Using BlazeDS

2010-11-01T17:11:00.001+05:30

Check out this SlideShare Presentation:

RIA With Flex & Java Using BlazeDS

View more presentations from hluu.

S-T-D

2010-09-28T22:40:00.000+05:30

What

STD is a Linux-based Security Tool. Actually, it is a collection of hundreds if not thousands of open source security tools. It's a Live Linux Distro, which means it runs from a bootable CD in memory without changing the native operating system of the host computer. Its sole purpose in life is to put as many security tools at your disposal with as slick an interface as it can.

Who

STD is meant to be used by both novice and professional security personnel but is not ideal for the Linux uninitiated. STD assumes you know the basics of Linux as most of your work will be done from the command line. If you are completely new to Linux, it's best you start with another live Distro like Knoppix to practice the basics (see faq).

STD is designed to assist network administrators and professionals alike secure their networks.

The STD community is extremely active. Come and join us on the forum here

The STD community is without exception White Hat. This means we will not entertain discussions on ANY illegal or unethical activities. Do Not ask.

Thank you :)

Configuring HTTPS for standalone tomcat

2010-09-27T13:06:00.000+05:30

its really simple.

1> make a security key.

from command line go to java bin and type :
use the same password for both acquires occations
keytool -genkey -alias tomcat -keyalg RSA

2> change the server.xml at tomcat conf folder and change like follows

uncomment the SSL configurations and add few other options to the Connector section:




   maxThreads="150" minSpareThreads="25" maxSpareThreads="75"
   enableLookups="false" disableUploadTimeout="true"
   acceptCount="100" scheme="https" secure="true"
   clientAuth="false" sslProtocol="TLS"
keystoreFile="${user.home}/.keystore"
keystorePass="adminabc123"/>

keystorePass="adminabc123" is the password you entered at the first step.

Password recover process for Unix like systems

2010-09-10T14:15:00.000+05:30

This post will help you to change the root password of Unix flavors on RedHat, Fedora, etc...

1.Let the system to boot.When the Boot Loader is starting.......

press 'e' to enter the menu edition dialog box. Then you will come to the following screen.

2.Confirm by pressing 'Enter key' to edit the boot configurations. You will see the advanced boot configuration menu with all available boot images.

3.Again press 'e', where you will end-up with following screen.

4. Here you can to set the Kernel Run Level: simply add :' 1' as done on the above figure. Then you Enter and you will come back to the Advanced boot menu. There you just press letter 'b' to start booting the system.

5.What we have done above is to change the boot-loader settings to change the boot configurations to make a minimum boot with single user mode run level.

So as expected you will end-up with LOVING #: root level access, and further its infinite access to the system.

6. Noe you can change the password easily:

type 'passwd' and yourpassword twice.

Now its back to usual x windows:

just restart the system using:

init 6

or reboot

or restart

Enjoy Linux with your new root password!!

Remember-> When you login next time its with username root

Enjoy!!! :-)