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• Java - JTable multiple instances

  - by Brian

  I have a JTable that gets data added to it from another JTable. Now I want to switch between JTables according to the day selected in a JComboBox. For example, if I choose Monday I add programs added to it then I select Tuesday from the JComboBox and a fresh JTable appears. If I go to Monday again the programs should still be there (until the program is closed). How do I create multiple JTables (the JTable remains the same) for the days and let the info remain there until program closure? Here is an example to show you what I mean:

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• Why does this break statement break not work?

  - by Roman

  I have the following code: public void post(String message) { final String mess = message; (new Thread() { public void run() { while (true) { try { if (status.equals("serviceResolved")) { output.println(mess); Game.log.fine("The following message was successfully sent: " + mess); break; } else { try {Thread.sleep(1000);} catch (InterruptedException ie) {} } } catch (NullPointerException e) { try {Thread.sleep(1000);} catch (InterruptedException ie) {} } } } }).start(); } In my log file I find a lot of lines like this: The following message was successfully sent: blablabla The following message was successfully sent: blablabla The following message was successfully sent: blablabla The following message was successfully sent: blablabla And my program is not responding. It seems to me that the break command does not work. What can be a possible reason for that. The interesting thing is that it happens not all the time. Sometimes my program works fine, sometimes the above described problem happens.

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• Counting the number of characters in a file

  - by Kat

  I'm writing a program that for one part asks for the program to print how many characters (including whitespaces) are in a file. The code I have right now though returns 0 every time though and I'm not sure why it isn't counting the characters. public int getcharCount(Scanner textFile) { int count = 0; while(textFile.hasNext()) { String line = textFile.nextLine(); for(int i=0; i < line.length(); i++) count++; } return count; }

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• Would someone mind giving suggestions for this new assembly language?

  - by Noctis Skytower

  Greetings! Last semester in college, my teacher in the Computer Languages class taught us the esoteric language named Whitespace. In the interest of learning the language better with a very busy schedule (midterms), I wrote an interpreter and assembler in Python. An assembly language was designed to facilitate writing programs easily, and a sample program was written with the given assembly mnemonics. Now that it is summer, a new project has begun with the objective being to rewrite the interpreter and assembler for Whitespace 0.3, with further developments coming afterwards. Since there is so much extra time than before to work on its design, you are presented here with an outline that provides a revised set of mnemonics for the assembly language. This post is marked as a wiki for their discussion. Have you ever had any experience with assembly languages in the past? Were there some instructions that you thought should have been renamed to something different? Did you find yourself thinking outside the box and with a different paradigm than in which the mnemonics were named? If you can answer yes to any of those questions, you are most welcome here. Subjective answers are appreciated! hold N Push the number onto the stack copy Duplicate the top item on the stack copy N Copy the nth item on the stack (given by the argument) onto the top of the stack swap Swap the top two items on the stack drop Discard the top item on the stack drop N Slide n items off the stack, keeping the top item add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo save Store load Retrieve L: Mark a location in the program call L Call a subroutine goto L Jump unconditionally to a label if=0 L Jump to a label if the top of the stack is zero if<0 L Jump to a label if the top of the stack is negative return End a subroutine and transfer control back to the caller exit End the program print chr Output the character at the top of the stack print int Output the number at the top of the stack input chr Read a character and place it in the location given by the top of the stack input int Read a number and place it in the location given by the top of the stack Question: How would you redesign, rewrite, or rename the previous mnemonics and for what reasons?

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• Using Qtcreator (with Qwt), really basic stuff

  - by Dago

  I'm trying to make a Qt program using Qtcreator and Qwt for plotting. I've never used Qtcreator before. I've created a mainwindow and added a Qwtplot widget there (object name: qwtPlot). The widget shows up in the program when I compile and run it. But theres no mention of the qwtPlot object anywhere in the (autogenerated) code so I assume it is being added at compile time from the .ui xml file (or something). My question is that... how do I modify/change the qwtPlot object? Or where should I place the code. I'm having a hard time articulating my question but the question basically is "How do I do anything with the qwtPlot widget which is created (graphically) with Qtcreator?". I've checked some tutorials but in the tutorials they add the widgets manually in the code, but I'd like to use Qtcreator (because my UI will be fairly complicated). This whole Qtcreator is pretty confusing...

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• How's my pygame code?

  - by Isaiah

  I'm still getting the hang of lots of things and thought I should post some code I made with pygame and get some feedback^^. I posted code here: http://urlvars.com/code/snippet/39272/my-bouncing-program http://urlvars.com/code/snippet/39273/my-bouncing-program-classes There's tome things that I implemented that I'm not using yet I just realized like a timer at the bottom of the main while loop. If my code isn't readable, I'm sorry, I'm self taught and this is the first code I've ever posted anywhere. By the way I made some variables that take the screensize and half it to find a point to spit out the squares, but when I try to use it, it makes a weird effect :/ Try switching the list i have in the newbyte() function with the halfScreen variable and see it freak out o.O thank you

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• Possible apache/mysql/php wrapper?

  - by MrStatic

  I was tasked with writing a smallish program for data input and manipulation. My language of choice happens to be PHP. I have written out the program/site it all works fine is easily portable and everything but have one question. Is there anyway to wrap up apache/mysql/php into a bundle of one exe? I know of MoWes Portable and other options but I am looking to basically wrap everything up into a single exe without much fuss to the end user. My target users are very low on the computer savvy scale. I am trying to avoid a batch file for launching and don't really want them able to shutdown one part on accident and not another (IE shut off mysql but leave apache on).

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• PHP MSSql Connection

  - by ajithperuva

  I am usign mssql as my backend for program.when i am try to connect with database which not shows any type of errors,but it is not working.Which is not getting connection. My code is like mssql_connect('localhost', 'db_user', 'db_password') or die('Error'); The funny thing is which is not connecting and also which is not show message Error.Why it is?Anybody can help me...please.... How can we enable mssql configuration using php program(what is the script for that.not manually).How could we know the actual status of mssql in server? Please help me.My application is working properly in local;the problem is about public hosting.

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• How is conversion of float/double to int handled in printf?

  - by Sandip

  Consider this program int main() { float f = 11.22; double d = 44.55; int i,j; i = f; //cast float to int j = d; //cast double to int printf("i = %d, j = %d, f = %d, d = %d", i,j,f,d); //This prints the following: // i = 11, j = 44, f = -536870912, d = 1076261027 return 0; } Can someone explain why the casting from double/float to int works correctly in the first case, and does not work when done in printf? This program was compiled on gcc-4.1.2 on 32-bit linux machine.

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• Undefined symbol sunOglCurPrimTablePtr in Solaris-x86

  - by yowkee

  I was porting a C++ program from Solaris Sparc to Solaris x86. The program utilizes OpenGL library and the compilation is performed in a Sun Ultra27 workstation with the default GCC (3.4.3) and OpenGL library come with the machine. However, the following OpenGL call couldn't found while linking: Undefined symbol first referenced in file sunOglCurPrimTablePtr ../../lib/libgltt.so sunOglCurrentContext ../../lib/libgltt.so which, both sunOglCurPrimTablePtr and sunOglCurrentContext should be available in the default OpenGL library /usr/lib/libGL.so (links to /usr/X11/lib/NVIDIA/libGL.so.1). But I couldn't find anything from it: > nm /usr/lib/libGL.so /usr/lib/libGL.so: Searching on web, SUN or Nvidia didn't lead to any helpful resource. Any clue or helps? Thanks!

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• how to set breakpoint on function in a shared library which has not been loaded in gdb

  - by pierr

  Hi, I have a shared library libtest.so which will be loaded into the the main program using dlopen. Function test() reside in libtest.so and will be called in the main program through dlsym. Is there any way I could set up a break point on test? Please note that the main programm has not been linked to libtest.so during linking time. Otherwise , I should be able to set the break point although it is a pending action. In my case, when I do b test, gdb will tell me Function "test" not defined.

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• Strcpy() corrupts the copied string in Solaris but not Linux

  - by strictlyrude27

  Hi all, I'm writing a C code for a class. This class requires that our code compile and run on the school server, which is a sparc solaris machine. I'm running Linux x64. I have this line to parse (THIS IS NOT ACTUAL CODE BUT IS INPUT TO MY PROGRAM): while ( cond1 ){ I need to capture the "while" and the "cond1" into separate strings. I've been using strtok() to do this. In Linux, the following lines: char *cond = NULL; cond = (char *)malloc(sizeof(char)); memset(cond, 0, sizeof(char)); strcpy(cond, strtok(NULL, ": \t\(){")); //already got the "while" out of the line will correctly capture the string "cond1".Running this on the solaris machine, however, gives me the string "cone1". Note that in plenty of other cases within my program, strings are being copied correctly. (For instance, the "while") was captured correctly. Does anyone know what is going on here?

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• SoundPlayer causing Memory Leaks?

  - by Nick Udell

  I'm writing a basic writing app in C# and I wanted to have the program make typewriter sounds as you typed. I've hooked the KeyPress event on my RichTextBox to a function that uses a SoundPlayer to play a short wav file every time a key is pressed, however I've noticed after a while my computer slows to a crawl and checking my processes, audiodlg.exe was using 5 GIGABYTES of RAM. The code I'm using is as follows: I initialise the SoundPlayer as a global variable on program start with SoundPlayer sp = new SoundPlayer("typewriter.wav") Then on the KeyPress event I simply call sp.Play(); Does anybody know what's causing the heavy memory usage? The file is less than a second long, so it shouldn't be clogging the thing up too much.

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• Using mx.charts in a Flex Hero mobile project

  - by Alexander Farber

  Hello, Adobe states that Charts are supported in mobile projects but when I try to change the following working files (created project with File - New - Flex Mobile Project - Google Nexus One): MyTest.mxml: <?xml version="1.0" encoding="utf-8"?> <s:MobileApplication xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark" firstView="views.MyTestHome"> <s:navigationContent> <s:Button label="Home" click="navigator.popToFirstView();"/> </s:navigationContent> <s:actionContent/> </s:MobileApplication> MyTestHome.mxml: <?xml version="1.0" encoding="utf-8"?> <s:View xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark" title="Test Chart"> </s:View> to the new MyTestHome.mxml: <?xml version="1.0" encoding="utf-8"?> <s:View xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:mx="library://ns.adobe.com/flex/mx" xmlns:s="library://ns.adobe.com/flex/spark" title="Test Chart"> <fx:Script> <![CDATA[ import mx.collections.*; [Bindable] private var medalsAC:ArrayCollection = new ArrayCollection( [ {Country: "USA", Gold: 35, Silver:39, Bronze: 29 }, {Country:"China", Gold: 32, Silver:17, Bronze: 14 }, {Country:"Russia", Gold: 27, Silver:27, Bronze: 38 } ]); ]]> </fx:Script> <mx:PieChart id="chart" height="100%" width="100%" paddingRight="5" paddingLeft="5" color="0x323232" dataProvider="{medalsAC}" > <mx:series> <mx:PieSeries labelPosition="callout" field="Gold"> <mx:calloutStroke> <s:SolidColorStroke weight="0" color="0x888888" alpha="1.0"/> </mx:calloutStroke> <mx:radialStroke> <s:SolidColorStroke weight="0" color="#FFFFFF" alpha="0.20"/> </mx:radialStroke> <mx:stroke> <s:SolidColorStroke color="0" alpha="0.20" weight="2"/> </mx:stroke> </mx:PieSeries> </mx:series> </mx:PieChart> </s:View> and also add c:\Program Files\Adobe\Adobe Flash Builder Burrito\sdks\4.5.0\frameworks\libs\datavisualization.swc c:\Program Files\Adobe\Adobe Flash Builder Burrito\sdks\4.5.0\frameworks\libs\sparkskins.swc c:\Program Files\Adobe\Adobe Flash Builder Burrito\sdks\4.5.0\frameworks\libs\mx\mx.swc to Flex Build Path (clicking "Add SWC" button): Then it fails with the error: Could not resolve to a component implementation. Does anybody please have an idea here? Alex

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• Key logging in .NET

  - by Moshe

  Is it possible to write a key logger in Visual Basic.NET? Is this the right language to be using? So far, I've gotten a console app to read input and append to a file. 1)How can I make a .NET program "catch" all keyboard input? 2)How do I make a process not show up in Task Manager? This is not for a virus, but rather a parental control program for a specific clientele. No malicious intent here.

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• Difference between 'scope' and 'namespace'?

  - by katriel

  What is the difference, in general, between the concepts of namespaces and scope? To my understanding, both describe the parts of a program in which a variable/object/method/function will be accessible. I understand that 'scope' tends to be a property of the variable (e.g., "This variable has global scope"), while a 'namespace' is a property of the program (e.g., "A Python function creates a local namespace"). Are there other differences? Global scope vs global namespace addresses a slightly narrower question: global namespaces in C++. http://www.alan-g.me.uk/tutor/tutname.htm states, There are a few very subtle differences between the terms but only a Computer Scientist pedant would argue with you, and for our purposes namespace and scope are identical. What are those subtle differences? Under what circumstances or with which kinds of languages do people use each concept?

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• C programing XML

  - by pedro

  HI...I'm making a project and the program receives info about people, how can i save all info to XML?

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• Retrieving the name of the current function in php

  - by Cian E

  Is there a function that can return the name of the current function a program is executing?

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• Start exe even with missing dependency dlls?

  - by k3b

  In Dotnet2.0 and later a program refuses to start if one of its dependent (static referenced) dlls are missing. With Dotnet1.1 and 1.0 the program started but crashed later when trying to use functionality of the missing assembly. I wonder if there is something like a compiler switch , configuration option or a dotnet [attribute] to allow me to start the app when certain dlls are missing. Is it possible without moidfying the sourcecode (execpt by applying some Attriutes)? I don't want to manualy load assemblies by programcode or use IOC-Framworks. Update: With "static referenced dlls" i mean the opposite of dynamicly loading a dll in my own programcode using reflection and Assembly.Loadxxxx(). Update 2010-12-25: This scenario happens for example if you want to use Log4net with Dotnet4 clientprofile together with a WinForms-Aplication: Log4net requires System.Web.dll that is not in Dotnet4-Clientprofile. You must install dotnet4-web-support to use the winforms-aplication that is compiled against log4net unless there is some magic Compiler-switch/Attribute/Configuration that i am still looking for.

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• winForms Booking Class Help

  - by cameron

  Hi, I am using C# Windows Forms in visual studio with different classes performing different functions in my program. I have a "Program" main class with the following information: static class Program { /// <summary> /// The main entry point for the application. /// </summary> [STAThread] static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(new Form1()); } } and a Screen class with the following information class Screen { public List<Show> shows { get; private set; } public int ScreenNumber { get; private set; } public Screen(int screenNumber, params Show[] schedule) { this.ScreenNumber = screenNumber; this.shows = schedule.ToList<Show>(); } } and a Seat class with the following information public class Seat { private string name; public bool IsAvailable { get; set; } public decimal Price { get; private set; } public int Number { get; private set; } public Seat(bool isAvailable, int number) { this.IsAvailable = isAvailable; this.name = String.Format("Seat {0}",number); this.Price = 7.50m; this.Number = number; } public override string ToString() { return this.name; } } and finally a Show class with the following information public class Show { private List<Seat> seats = new List<Seat>(); public string Title { get; private set; } public string Time { get; private set; } public int ScreenNumber { get; private set; } public List<Seat> Seats { get { return this.seats; } } public Show(string title, DateTime time, int screenNumber, int numberOfSeats) { this.Title = title; this.Time = time.ToShortTimeString(); this.ScreenNumber = screenNumber; this.initSeats(numberOfSeats); } private void initSeats(int numberOfSeats) { for (int i = 0; i < numberOfSeats; i++) this.seats.Add(new Seat(true, i + 1)); } }` these all feed into two different winForms to create a booking system for shows. therefore i need to collate the data given in program and output it into a txt file. any help will be much appreciated NOTE: the code for FORM1 which allows the user to select which show they want is: namespace CindysSeats { public partial class Form1 : Form { private Cinema cinema = new Cinema(); //booked show could be added to booking object when you create it so that it is easily writable to the external file private Show selectedShow; public Form1() { InitializeComponent(); this.showList_dg.DataSource = this.cinema.GetShowList(); } private void showList_dg_RowHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e) { Show selectedShow = this.selectedShow = this.cinema.GetShowList()[e.RowIndex]; this.showTitle_lbl.Text = selectedShow.Title; this.showTime_lbl.Text = selectedShow.Time; this.showScreen_lbl.Text = selectedShow.ScreenNumber.ToString(); } private void confirmShow_btn_Click(object sender, EventArgs e) { if (this.selectedShow == null) return; Form2 seats = new Form2(this.selectedShow); seats.Show(); } And the code for FORM2 which is where the user selects their seats they want is: namespace CindysSeats { public partial class Form2 : Form { //booked seats could be added to booking object when you create it so that it is easily writable to the external file private List<Seat> bookedSeats = new List<Seat>(); private Show selectedShow; public Form2(Show selectedShow) { InitializeComponent(); this.selectedShow = selectedShow; this.showSeats_dg.DataSource = this.selectedShow.Seats; } private void showSeats_dg_RowHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e) { Seat selectedSeat = this.selectedShow.Seats[e.RowIndex]; if(this.bookedSeats.Contains(selectedSeat)) return; if(!selectedSeat.IsAvailable) return; this.bookedSeats.Add(selectedSeat); this.bookedSeats_lv.Items.Add(selectedSeat.ToString() + " " + selectedSeat.Price.ToString()+"\n"); this.bookedSeats_lv.Invalidate(); } private void bookSeats_btn_Click(object sender, EventArgs e) { } } thank you for helping

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• Mac OS X bluetooth programming sample ?

  - by tuttu47

  Hi, I am trying to develop an application using bluetooth in my MAC mini. However, after searching all over net, all that I could find was the "Bluetooth Device Access Guide" from apple, and not a single sample program ! Is any sample code for this available ? I will also explain what I am trying to do in my program, so that if any of you can help me.... I want pair my iPhone with my MAC programmatically over the PAN profile, and then send data (streams) both-ways. I paired them manually, and I was successfully able to transfer data. I just want to do that programmatically ! Any help would be appreciated ...

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• Static libraries, dynamic libraries, DLLs, entry points, headers ... how to get out of this alive?

  - by tunnuz

  Hello, I recently had to program C++ under Windows for an University project, and I'm pretty confused about static and dynamic libraries system, what the compiler needs, what the linker needs, how to build a library ... is there any good document about this out there? I'm pretty confused about the *nix library system as well (so, dylibs, the ar tool, how to compile them ...), can you point a review document about the current library techniques on the various architectures? Note: due to my poor knowledge this message could contain wrong concepts, feel free to edit it. Thank you Feel free to add more reference, I will add them to the summary. References Since most of you posted *nix or Windows specific references I will summarize here the best ones, I will mark as accepted answer the Wikipedia one, because is a good start point (and has references inside too) to get introduced to this stuff. Program Library Howto (Unix) Dynamic-Link Libraries (from MSDN) (Windows) DLL Information (StackOverflow) (Windows) Programming in C (Unix) An Overview of Compiling and Linking (Windows)

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• Speech Recognition Server Does Not Stay Open

  - by Waffle

  I am trying to create a simple program that loops for user speech input using com.apple.speech.recognitionserver. My code thus far is as follows: set user_response to "start" repeat while user_response is not equal to "Exit" tell application id "com.apple.speech.recognitionserver" set user_response to listen for {"Time", "Weather", "Exit"} with prompt "Good Morning" end tell if user_response = "Time" then set curr_time to time string of (the current date) set curr_day to weekday of (the current date) say "It is" say curr_time say "on" say curr_day say "day" else if user_response = "Weather" then say "It is hot outside. What do you expect?" end if end repeat say "Have a good day" If the above is run on my system it says good morning and it then pops up with the speech input system and waits for either Time, Weather, or Exit. They all do what they say they are going to do, but instead of looping if I say Time and Weather and asking again until I say exit the speechserver times out and never pops up again. Is there a way of either keeping that application open until the program ends or is applescript not capable of looping for user speech input?

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• ASMLib

  - by wcoekaer

  Oracle ASMlib on Linux has been a topic of discussion a number of times since it was released way back when in 2004. There is a lot of confusion around it and certainly a lot of misinformation out there for no good reason. Let me try to give a bit of history around Oracle ASMLib. Oracle ASMLib was introduced at the time Oracle released Oracle Database 10g R1. 10gR1 introduced a very cool important new features called Oracle ASM (Automatic Storage Management). A very simplistic description would be that this is a very sophisticated volume manager for Oracle data. Give your devices directly to the ASM instance and we manage the storage for you, clustered, highly available, redundant, performance, etc, etc... We recommend using Oracle ASM for all database deployments, single instance or clustered (RAC). The ASM instance manages the storage and every Oracle server process opens and operates on the storage devices like it would open and operate on regular datafiles or raw devices. So by default since 10gR1 up to today, we do not interact differently with ASM managed block devices than we did before with a datafile being mapped to a raw device. All of this is without ASMLib, so ignore that one for now. Standard Oracle on any platform that we support (Linux, Windows, Solaris, AIX, ...) does it the exact same way. You start an ASM instance, it handles storage management, all the database instances use and open that storage and read/write from/to it. There are no extra pieces of software needed, including on Linux. ASM is fully functional and selfcontained without any other components. In order for the admin to provide a raw device to ASM or to the database, it has to have persistent device naming. If you booted up a server where a raw disk was named /dev/sdf and you give it to ASM (or even just creating a tablespace without asm on that device with datafile '/dev/sdf') and next time you boot up and that device is now /dev/sdg, you end up with an error. Just like you can't just change datafile names, you can't change device filenames without telling the database, or ASM. persistent device naming on Linux, especially back in those days ways to say it bluntly, a nightmare. In fact there were a number of issues (dating back to 2004) : Linux async IO wasn't pretty persistent device naming including permissions (had to be owned by oracle and the dba group) was very, very difficult to manage system resource usage in terms of open file descriptors So given the above, we tried to find a way to make this easier on the admins, in many ways, similar to why we started working on OCFS a few years earlier - how can we make life easier for the admins on Linux. A feature of Oracle ASM is the ability for third parties to write an extension using what's called ASMLib. It is possible for any third party OS or storage vendor to write a library using a specific Oracle defined interface that gets used by the ASM instance and by the database instance when available. This interface offered 2 components : Define an IO interface - allow any IO to the devices to go through ASMLib Define device discovery - implement an external way of discovering, labeling devices to provide to ASM and the Oracle database instance This is similar to a library that a number of companies have implemented over many years called libODM (Oracle Disk Manager). ODM was specified many years before we introduced ASM and allowed third party vendors to implement their own IO routines so that the database would use this library if installed and make use of the library open/read/write/close,.. routines instead of the standard OS interfaces. PolyServe back in the day used this to optimize their storage solution, Veritas used (and I believe still uses) this for their filesystem. It basically allowed, in particular, filesystem vendors to write libraries that could optimize access to their storage or filesystem.. so ASMLib was not something new, it was basically based on the same model. You have libodm for just database access, you have libasm for asm/database access. Since this library interface existed, we decided to do a reference implementation on Linux. We wrote an ASMLib for Linux that could be used on any Linux platform and other vendors could see how this worked and potentially implement their own solution. As I mentioned earlier, ASMLib and ODMLib are libraries for third party extensions. ASMLib for Linux, since it was a reference implementation implemented both interfaces, the storage discovery part and the IO part. There are 2 components : Oracle ASMLib - the userspace library with config tools (a shared object and some scripts) oracleasm.ko - a kernel module that implements the asm device for /dev/oracleasm/* The userspace library is a binary-only module since it links with and contains Oracle header files but is generic, we only have one asm library for the various Linux platforms. This library is opened by Oracle ASM and by Oracle database processes and this library interacts with the OS through the asm device (/dev/asm). It can install on Oracle Linux, on SuSE SLES, on Red Hat RHEL,.. The library itself doesn't actually care much about the OS version, the kernel module and device cares. The support tools are simple scripts that allow the admin to label devices and scan for disks and devices. This way you can say create an ASM disk label foo on, currently /dev/sdf... So if /dev/sdf disappears and next time is /dev/sdg, we just scan for the label foo and we discover it as /dev/sdg and life goes on without any worry. Also, when the database needs access to the device, we don't have to worry about file permissions or anything it will be taken care of. So it's a convenience thing. The kernel module oracleasm.ko is a Linux kernel module/device driver. It implements a device /dev/oracleasm/* and any and all IO goes through ASMLib - /dev/oracleasm. This kernel module is obviously a very specific Oracle related device driver but it was released under the GPL v2 so anyone could easily build it for their Linux distribution kernels. Advantages for using ASMLib : A good async IO interface for the database, the entire IO interface is based on an optimal ASYNC model for performance A single file descriptor per Oracle process, not one per device or datafile per process reducing # of open filehandles overhead Device scanning and labeling built-in so you do not have to worry about messing with udev or devlabel, permissions or the likes which can be very complex and error prone. Just like with OCFS and OCFS2, each kernel version (major or minor) has to get a new version of the device drivers. We started out building the oracleasm kernel module rpms for many distributions, SLES (in fact in the early days still even for this thing called United Linux) and RHEL. The driver didn't make sense to get pushed into upstream Linux because it's unique and specific to the Oracle database. As it takes a huge effort in terms of build infrastructure and QA and release management to build kernel modules for every architecture, every linux distribution and every major and minor version we worked with the vendors to get them to add this tiny kernel module to their infrastructure. (60k source code file). The folks at SuSE understood this was good for them and their customers and us and added it to SLES. So every build coming from SuSE for SLES contains the oracleasm.ko module. We weren't as successful with other vendors so for quite some time we continued to build it for RHEL and of course as we introduced Oracle Linux end of 2006 also for Oracle Linux. With Oracle Linux it became easy for us because we just added the code to our build system and as we churned out Oracle Linux kernels whether it was for a public release or for customers that needed a one off fix where they also used asmlib, we didn't have to do any extra work it was just all nicely integrated. With the introduction of Oracle Linux's Unbreakable Enterprise Kernel and our interest in being able to exploit ASMLib more, we started working on a very exciting project called Data Integrity. Oracle (Martin Petersen in particular) worked for many years with the T10 standards committee and storage vendors and implemented Linux kernel support for DIF/DIX, data protection in the Linux kernel, note to those that wonder, yes it's all in mainline Linux and under the GPL. This basically gave us all the features in the Linux kernel to checksum a data block, send it to the storage adapter, which can then validate that block and checksum in firmware before it sends it over the wire to the storage array, which can then do another checksum and to the actual DISK which does a final validation before writing the block to the physical media. So what was missing was the ability for a userspace application (read: Oracle RDBMS) to write a block which then has a checksum and validation all the way down to the disk. application to disk. Because we have ASMLib we had an entry into the Linux kernel and Martin added support in ASMLib (kernel driver + userspace) for this functionality. Now, this is all based on relatively current Linux kernels, the oracleasm kernel module depends on the main kernel to have support for it so we can make use of it. Thanks to UEK and us having the ability to ship a more modern, current version of the Linux kernel we were able to introduce this feature into ASMLib for Linux from Oracle. This combined with the fact that we build the asm kernel module when we build every single UEK kernel allowed us to continue improving ASMLib and provide it to our customers. So today, we (Oracle) provide Oracle ASMLib for Oracle Linux and in particular on the Unbreakable Enterprise Kernel. We did the build/testing/delivery of ASMLib for RHEL until RHEL5 but since RHEL6 decided that it was too much effort for us to also maintain all the build and test environments for RHEL and we did not have the ability to use the latest kernel features to introduce the Data Integrity features and we didn't want to end up with multiple versions of asmlib as maintained by us. SuSE SLES still builds and comes with the oracleasm module and they do all the work and RHAT it certainly welcome to do the same. They don't have to rebuild the userspace library, it's really about the kernel module. And finally to re-iterate a few important things : Oracle ASM does not in any way require ASMLib to function completely. ASMlib is a small set of extensions, in particular to make device management easier but there are no extra features exposed through Oracle ASM with ASMLib enabled or disabled. Often customers confuse ASMLib with ASM. again, ASM exists on every Oracle supported OS and on every supported Linux OS, SLES, RHEL, OL withoutASMLib Oracle ASMLib userspace is available for OTN and the kernel module is shipped along with OL/UEK for every build and by SuSE for SLES for every of their builds ASMLib kernel module was built by us for RHEL4 and RHEL5 but we do not build it for RHEL6, nor for the OL6 RHCK kernel. Only for UEK ASMLib for Linux is/was a reference implementation for any third party vendor to be able to offer, if they want to, their own version for their own OS or storage ASMLib as provided by Oracle for Linux continues to be enhanced and evolve and for the kernel module we use UEK as the base OS kernel hope this helps.

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• GUI freezing after datagridviews have been updated using backgroundworkers

  - by Jhon

  I have made an application which runs three backgroundworkers simultaneously. It basically updates three datagridviews, which it is doing spot on. My problem is if I press maximizebox button or anywhere in any of the datagridview the program hangs for quite a long time. I am able to use the horizontal scroll but not vertical scrolls. I have tried Backgroundworker_runworkercompleted and it fires as required after threads have updated their respective datagridviews. Is it a normal behaviour or am i doing something wrong any suggestions would be helpful. P.S: I have run the whole program using step method and their is no infinite loop in the code. Thanks in advance Jhon

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