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  • Trouble Percent-Encoding Spaces in Java

    - by behrk2
    Hi Everyone, I am using the URLUTF8Encoder.java class from W3C (www.w3.org/International/URLUTF8Encoder.java). Currently, it will encode any blank spaces ' ' into plus signs '+'. I am having difficulty modifying the code to percent-encode the blank space into '%20'. Unfortunately, I am not too familiar with hex. Can anyone help me out? I need to modify this snippet... else if (ch == ' ') { // space sbuf.append('+'); in the following code: final static String[] hex = { "%00", "%01", "%02", "%03", "%04", "%05", "%06", "%07", "%08", "%09", "%0A", "%0B", "%0C", "%0D", "%0E", "%0F", "%10", "%11", "%12", "%13", "%14", "%15", "%16", "%17", "%18", "%19", "%1A", "%1B", "%1C", "%1D", "%1E", "%1F", "%20", "%21", "%22", "%23", "%24", "%25", "%26", "%27", "%28", "%29", "%2A", "%2B", "%2C", "%2D", "%2E", "%2F", "%30", "%31", "%32", "%33", "%34", "%35", "%36", "%37", "%38", "%39", "%3A", "%3B", "%3C", "%3D", "%3E", "%3F", "%40", "%41", "%42", "%43", "%44", "%45", "%46", "%47", "%48", "%49", "%4A", "%4B", "%4C", "%4D", "%4E", "%4F", "%50", "%51", "%52", "%53", "%54", "%55", "%56", "%57", "%58", "%59", "%5A", "%5B", "%5C", "%5D", "%5E", "%5F", "%60", "%61", "%62", "%63", "%64", "%65", "%66", "%67", "%68", "%69", "%6A", "%6B", "%6C", "%6D", "%6E", "%6F", "%70", "%71", "%72", "%73", "%74", "%75", "%76", "%77", "%78", "%79", "%7A", "%7B", "%7C", "%7D", "%7E", "%7F", "%80", "%81", "%82", "%83", "%84", "%85", "%86", "%87", "%88", "%89", "%8A", "%8B", "%8C", "%8D", "%8E", "%8F", "%90", "%91", "%92", "%93", "%94", "%95", "%96", "%97", "%98", "%99", "%9A", "%9B", "%9C", "%9D", "%9E", "%9F", "%A0", "%A1", "%A2", "%A3", "%A4", "%A5", "%A6", "%A7", "%A8", "%A9", "%AA", "%AB", "%AC", "%AD", "%AE", "%AF", "%B0", "%B1", "%B2", "%B3", "%B4", "%B5", "%B6", "%B7", "%B8", "%B9", "%BA", "%BB", "%BC", "%BD", "%BE", "%BF", "%C0", "%C1", "%C2", "%C3", "%C4", "%C5", "%C6", "%C7", "%C8", "%C9", "%CA", "%CB", "%CC", "%CD", "%CE", "%CF", "%D0", "%D1", "%D2", "%D3", "%D4", "%D5", "%D6", "%D7", "%D8", "%D9", "%DA", "%DB", "%DC", "%DD", "%DE", "%DF", "%E0", "%E1", "%E2", "%E3", "%E4", "%E5", "%E6", "%E7", "%E8", "%E9", "%EA", "%EB", "%EC", "%ED", "%EE", "%EF", "%F0", "%F1", "%F2", "%F3", "%F4", "%F5", "%F6", "%F7", "%F8", "%F9", "%FA", "%FB", "%FC", "%FD", "%FE", "%FF" }; public static String encode(String s) { StringBuffer sbuf = new StringBuffer(); int len = s.length(); for (int i = 0; i < len; i++) { int ch = s.charAt(i); if ('A' <= ch && ch <= 'Z') { // 'A'..'Z' sbuf.append((char) ch); } else if ('a' <= ch && ch <= 'z') { // 'a'..'z' sbuf.append((char) ch); } else if ('0' <= ch && ch <= '9') { // '0'..'9' sbuf.append((char) ch); } else if (ch == ' ') { // space sbuf.append('+'); } else if (ch == '-' || ch == '_' // unreserved || ch == '.' || ch == '!' || ch == '~' || ch == '*' || ch == '\'' || ch == '(' || ch == ')') { sbuf.append((char) ch); } else if (ch <= 0x007f) { // other ASCII sbuf.append(hex[ch]); } else if (ch <= 0x07FF) { // non-ASCII <= 0x7FF sbuf.append(hex[0xc0 | (ch >> 6)]); sbuf.append(hex[0x80 | (ch & 0x3F)]); } else { // 0x7FF < ch <= 0xFFFF sbuf.append(hex[0xe0 | (ch >> 12)]); sbuf.append(hex[0x80 | ((ch >> 6) & 0x3F)]); sbuf.append(hex[0x80 | (ch & 0x3F)]); } } return sbuf.toString(); } Thanks!

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  • Have suggestions for these assembly mnemonics?

    - 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! Stack Manipulation (IMP: [Space]) Stack manipulation is one of the more common operations, hence the shortness of the IMP [Space]. There are four stack instructions. 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 Arithmetic (IMP: [Tab][Space]) Arithmetic commands operate on the top two items on the stack, and replace them with the result of the operation. The first item pushed is considered to be left of the operator. add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo Heap Access (IMP: [Tab][Tab]) Heap access commands look at the stack to find the address of items to be stored or retrieved. To store an item, push the address then the value and run the store command. To retrieve an item, push the address and run the retrieve command, which will place the value stored in the location at the top of the stack. save Store load Retrieve Flow Control (IMP: [LF]) Flow control operations are also common. Subroutines are marked by labels, as well as the targets of conditional and unconditional jumps, by which loops can be implemented. Programs must be ended by means of [LF][LF][LF] so that the interpreter can exit cleanly. 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 halt End the program I/O (IMP: [Tab][LF]) Finally, we need to be able to interact with the user. There are IO instructions for reading and writing numbers and individual characters. With these, string manipulation routines can be written. The read instructions take the heap address in which to store the result from the top of the stack. 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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  • Are their any 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! Stack Manipulation (IMP: [Space]) Stack manipulation is one of the more common operations, hence the shortness of the IMP [Space]. There are four stack instructions. 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 Arithmetic (IMP: [Tab][Space]) Arithmetic commands operate on the top two items on the stack, and replace them with the result of the operation. The first item pushed is considered to be left of the operator. add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo Heap Access (IMP: [Tab][Tab]) Heap access commands look at the stack to find the address of items to be stored or retrieved. To store an item, push the address then the value and run the store command. To retrieve an item, push the address and run the retrieve command, which will place the value stored in the location at the top of the stack. save Store load Retrieve Flow Control (IMP: [LF]) Flow control operations are also common. Subroutines are marked by labels, as well as the targets of conditional and unconditional jumps, by which loops can be implemented. Programs must be ended by means of [LF][LF][LF] so that the interpreter can exit cleanly. 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 I/O (IMP: [Tab][LF]) Finally, we need to be able to interact with the user. There are IO instructions for reading and writing numbers and individual characters. With these, string manipulation routines can be written. The read instructions take the heap address in which to store the result from the top of the stack. 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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  • Are there any suggestions for these new assembly mnemonics?

    - 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! Stack Manipulation (IMP: [Space]) Stack manipulation is one of the more common operations, hence the shortness of the IMP [Space]. There are four stack instructions. 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 Arithmetic (IMP: [Tab][Space]) Arithmetic commands operate on the top two items on the stack, and replace them with the result of the operation. The first item pushed is considered to be left of the operator. add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo Heap Access (IMP: [Tab][Tab]) Heap access commands look at the stack to find the address of items to be stored or retrieved. To store an item, push the address then the value and run the store command. To retrieve an item, push the address and run the retrieve command, which will place the value stored in the location at the top of the stack. save Store load Retrieve Flow Control (IMP: [LF]) Flow control operations are also common. Subroutines are marked by labels, as well as the targets of conditional and unconditional jumps, by which loops can be implemented. Programs must be ended by means of [LF][LF][LF] so that the interpreter can exit cleanly. 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 halt End the program I/O (IMP: [Tab][LF]) Finally, we need to be able to interact with the user. There are IO instructions for reading and writing numbers and individual characters. With these, string manipulation routines can be written. The read instructions take the heap address in which to store the result from the top of the stack. 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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  • Do you have suggestions for these assembly mnemonics?

    - 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! Stack Manipulation (IMP: [Space]) Stack manipulation is one of the more common operations, hence the shortness of the IMP [Space]. There are four stack instructions. 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 Arithmetic (IMP: [Tab][Space]) Arithmetic commands operate on the top two items on the stack, and replace them with the result of the operation. The first item pushed is considered to be left of the operator. add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo Heap Access (IMP: [Tab][Tab]) Heap access commands look at the stack to find the address of items to be stored or retrieved. To store an item, push the address then the value and run the store command. To retrieve an item, push the address and run the retrieve command, which will place the value stored in the location at the top of the stack. save Store load Retrieve Flow Control (IMP: [LF]) Flow control operations are also common. Subroutines are marked by labels, as well as the targets of conditional and unconditional jumps, by which loops can be implemented. Programs must be ended by means of [LF][LF][LF] so that the interpreter can exit cleanly. 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 halt End the program I/O (IMP: [Tab][LF]) Finally, we need to be able to interact with the user. There are IO instructions for reading and writing numbers and individual characters. With these, string manipulation routines can be written. The read instructions take the heap address in which to store the result from the top of the stack. 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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  • Stopping the animation after you let go of a key

    - by Michael Zeuner
    What I have right now is an animation that starts when I press space: if(input.isKeyDown(Input.KEY_SPACE)) player = movingRightSwingingSword; However when I stop clicking space my animation continues. until I move my player, how do I make it so it stops the animation right when you let go of space? A few lines Animation player, movingUp, movingDown, movingLeft, movingRight, movingRightSwingingSword; int[] duration = {200,200}; public void init(GameContainer gc, StateBasedGame sbg) throws SlickException { Image[] attackRight = {new Image("res/buckysRightSword1.png"), new Image("res/buckysRightSword2.png")}; movingRightSwingingSword = new Animation(attackRight, duration, true); } public void update(GameContainer gc, StateBasedGame sbg, int delta) throws SlickException { if(input.isKeyDown(Input.KEY_SPACE)) player = movingRightSwingingSword; } Full Code package javagame; import org.newdawn.slick.*; import org.newdawn.slick.state.*; public class Play extends BasicGameState { Animation player, movingUp, movingDown, movingLeft, movingRight, movingRightSwingingSword; Image worldMap; boolean quit = false; int[] duration = {200,200}; float playerPositionX = 0; float playerPositionY = 0; float shiftX = playerPositionX + 320; float shiftY = playerPositionY + 160; public Play(int state) { } public void init(GameContainer gc, StateBasedGame sbg) throws SlickException { worldMap = new Image("res/world.png"); Image[] walkUp = {new Image("res/buckysBack.png"), new Image("res/buckysBack.png")}; Image[] walkDown = {new Image("res/buckysFront.png"), new Image("res/buckysFront.png")}; Image[] walkLeft = {new Image("res/buckysLeft.png"), new Image("res/buckysLeft.png")}; Image[] walkRight = {new Image("res/buckysRight.png"), new Image("res/buckysRight.png")}; Image[] attackRight = {new Image("res/buckysRightSword1.png"), new Image("res/buckysRightSword2.png")}; movingUp = new Animation(walkUp, duration, false); movingDown = new Animation(walkDown, duration, false); movingLeft = new Animation(walkLeft, duration, false); movingRight = new Animation(walkRight, duration, false); //doesnt work! vvv movingRightSwingingSword = new Animation(attackRight, duration, true); player = movingDown; } public void render(GameContainer gc, StateBasedGame sbg, Graphics g) throws SlickException { worldMap.draw(playerPositionX, playerPositionY); player.draw(shiftX, shiftY); g.drawString("Player X: " + playerPositionX + "\nPlayer Y: " + playerPositionY, 400, 20); if (quit == true) { g.drawString("Resume (R)", 250, 100); g.drawString("MainMenu (M)", 250, 150); g.drawString("Quit Game (Q)", 250, 200); if (quit==false) { g.clear(); } } } public void update(GameContainer gc, StateBasedGame sbg, int delta) throws SlickException { Input input = gc.getInput(); if(input.isKeyDown(Input.KEY_UP)) { player = movingUp; playerPositionY += delta * .1f; if(playerPositionY>162) playerPositionY -= delta * .1f; } if(input.isKeyDown(Input.KEY_DOWN)) { player = movingDown; playerPositionY -= delta * .1f; if(playerPositionY<-600) playerPositionY += delta * .1f; } if(input.isKeyDown(Input.KEY_RIGHT)) { player = movingRight; playerPositionX -= delta * .1f; if(playerPositionX<-840) playerPositionX += delta * .1f; } if(input.isKeyDown(Input.KEY_LEFT)) { player = movingLeft; playerPositionX += delta * .1f; if(playerPositionX>318) playerPositionX -= delta * .1f; } if(input.isKeyDown(Input.KEY_SPACE)) player = movingRightSwingingSword; if(input.isKeyDown(Input.KEY_ESCAPE)) quit = true; if(input.isKeyDown(Input.KEY_R)) if (quit == true) quit = false; if(input.isKeyDown(Input.KEY_M)) if (quit == true) {sbg.enterState(0); quit = false;} if(input.isKeyDown(Input.KEY_Q)) if (quit == true) System.exit(0); } public int getID() { return 1; } }

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  • New line (in the code) after <li> element breaking layout

    - by BT643
    Weirdly, I've never come across this issue before, but I've just started making a site and the top navigation isn't playing nicely. I want a small amount of white space between each menu item, but when I have new lines between my <li> elements and my <a> elements in my IDE (Netbeans), the white space disappears, yet it looks fine if I have <li><a></a></li> all on the same line. I was always under the impression html ignored white space in the code. I've checked for any weird characters causing problems in other text editors and can't find anything. Here's the code... Like this the menu looks correct but code looks ugly (I know it looks fine when it's this simple, but I'm going be adding more complexity in which makes it look awful all on one line): <ul id="menu"> <li><a href="#">About</a></li> <li class="active"><a href="<?php echo site_url("tracklist"); ?>">Track List</a></li> <li><a href="<?php echo site_url("stats"); ?>">Stats</a></li> <li><a href="#">Stats</a></li> </ul> Like this the menu looks wrong but code looks fine: <ul id="menu"> <li> <a href="#">About</a> </li> <li class="active"> <a href="<?php echo site_url("tracklist"); ?>">Track List</a> </li> <li> <a href="<?php echo site_url("stats"); ?>">Stats</a> </li> <li> <a href="#">Stats</a> </li> </ul> Here's the css: #menu { float: right; } #menu li { display: inline-block; padding: 5px; background-color: #932996; border-bottom: solid 1px #932996; } #menu li:hover { border-bottom: solid 3px #FF0000; } #menu li.active { background-color: #58065e; } I'm sure it's something simple I'm doing wrong... but can someone shed some light on this for me? Sorry for the lengthy post (my first on stackoverflow).

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  • How does java.util.Collections.contains() perform faster than a linear search?

    - by The111
    I've been fooling around with a bunch of different ways of searching collections, collections of collections, etc. Doing lots of stupid little tests to verify my understanding. Here is one which boggles me (source code further below). In short, I am generating N random integers and adding them to a list. The list is NOT sorted. I then use Collections.contains() to look for a value in the list. I intentionally look for a value that I know won't be there, because I want to ensure that the entire list space is probed. I time this search. I then do another linear search manually, iterating through each element of the list and checking if it matches my target. I also time this search. On average, the second search takes 33% longer than the first one. By my logic, the first search must also be linear, because the list is unsorted. The only possibility I could think of (which I immediately discard) is that Java is making a sorted copy of my list just for the search, but (1) I did not authorize that usage of memory space and (2) I would think that would result in MUCH more significant time savings with such a large N. So if both searches are linear, they should both take the same amount of time. Somehow the Collections class has optimized this search, but I can't figure out how. So... what am I missing? import java.util.*; public class ListSearch { public static void main(String[] args) { int N = 10000000; // number of ints to add to the list int high = 100; // upper limit for random int generation List<Integer> ints; int target = -1; // target will not be found, forces search of entire list space long start; long end; ints = new ArrayList<Integer>(); start = System.currentTimeMillis(); System.out.print("Generating new list... "); for (int i = 0; i < N; i++) { ints.add(((int) (Math.random() * high)) + 1); } end = System.currentTimeMillis(); System.out.println("took " + (end-start) + "ms."); start = System.currentTimeMillis(); System.out.print("Searching list for target (method 1)... "); if (ints.contains(target)) { // nothing } end = System.currentTimeMillis(); System.out.println(" Took " + (end-start) + "ms."); System.out.println(); ints = new ArrayList<Integer>(); start = System.currentTimeMillis(); System.out.print("Generating new list... "); for (int i = 0; i < N; i++) { ints.add(((int) (Math.random() * high)) + 1); } end = System.currentTimeMillis(); System.out.println("took " + (end-start) + "ms."); start = System.currentTimeMillis(); System.out.print("Searching list for target (method 2)... "); for (Integer i : ints) { // nothing } end = System.currentTimeMillis(); System.out.println(" Took " + (end-start) + "ms."); } }

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  • QuickReport.ExportToFilter throws "stack overflow" error when used in TWebModule

    - by M Schenkel
    I have a web application using the TWebModule component. It runs as a module on Apache. The code below throws a "Stack Overflow" error on the ExportToFilter. The same exact code works fine from a Winforms Application and even a service for that matter. I have seen other discussions on this which indicate it has something to do with threading. var mFileName: String; AExportFilter:; begin mFileName := 'c:\temp\calendar.pdf'; AExportFilter:=TQRPDFDocumentFilter.Create(mFileName); try WebSchdHistCalendarForm := TWebSchdHistCalendarForm.create(nil); WebSchdHistCalendarForm.quickrep1.ShowProgress := False; WebSchdHistCalendarForm.quickrep1.ExportToFilter(AExportFilter ); finally AExportFilter.Free; WebSchdHistCalendarForm.Free; end;

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  • Parallelism in .NET – Part 2, Simple Imperative Data Parallelism

    - by Reed
    In my discussion of Decomposition of the problem space, I mentioned that Data Decomposition is often the simplest abstraction to use when trying to parallelize a routine.  If a problem can be decomposed based off the data, we will often want to use what MSDN refers to as Data Parallelism as our strategy for implementing our routine.  The Task Parallel Library in .NET 4 makes implementing Data Parallelism, for most cases, very simple. Data Parallelism is the main technique we use to parallelize a routine which can be decomposed based off data.  Data Parallelism refers to taking a single collection of data, and having a single operation be performed concurrently on elements in the collection.  One side note here: Data Parallelism is also sometimes referred to as the Loop Parallelism Pattern or Loop-level Parallelism.  In general, for this series, I will try to use the terminology used in the MSDN Documentation for the Task Parallel Library.  This should make it easier to investigate these topics in more detail. Once we’ve determined we have a problem that, potentially, can be decomposed based on data, implementation using Data Parallelism in the TPL is quite simple.  Let’s take our example from the Data Decomposition discussion – a simple contrast stretching filter.  Here, we have a collection of data (pixels), and we need to run a simple operation on each element of the pixel.  Once we know the minimum and maximum values, we most likely would have some simple code like the following: for (int row=0; row < pixelData.GetUpperBound(0); ++row) { for (int col=0; col < pixelData.GetUpperBound(1); ++col) { pixelData[row, col] = AdjustContrast(pixelData[row, col], minPixel, maxPixel); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This simple routine loops through a two dimensional array of pixelData, and calls the AdjustContrast routine on each pixel. As I mentioned, when you’re decomposing a problem space, most iteration statements are potentially candidates for data decomposition.  Here, we’re using two for loops – one looping through rows in the image, and a second nested loop iterating through the columns.  We then perform one, independent operation on each element based on those loop positions. This is a prime candidate – we have no shared data, no dependencies on anything but the pixel which we want to change.  Since we’re using a for loop, we can easily parallelize this using the Parallel.For method in the TPL: Parallel.For(0, pixelData.GetUpperBound(0), row => { for (int col=0; col < pixelData.GetUpperBound(1); ++col) { pixelData[row, col] = AdjustContrast(pixelData[row, col], minPixel, maxPixel); } }); Here, by simply changing our first for loop to a call to Parallel.For, we can parallelize this portion of our routine.  Parallel.For works, as do many methods in the TPL, by creating a delegate and using it as an argument to a method.  In this case, our for loop iteration block becomes a delegate creating via a lambda expression.  This lets you write code that, superficially, looks similar to the familiar for loop, but functions quite differently at runtime. We could easily do this to our second for loop as well, but that may not be a good idea.  There is a balance to be struck when writing parallel code.  We want to have enough work items to keep all of our processors busy, but the more we partition our data, the more overhead we introduce.  In this case, we have an image of data – most likely hundreds of pixels in both dimensions.  By just parallelizing our first loop, each row of pixels can be run as a single task.  With hundreds of rows of data, we are providing fine enough granularity to keep all of our processors busy. If we parallelize both loops, we’re potentially creating millions of independent tasks.  This introduces extra overhead with no extra gain, and will actually reduce our overall performance.  This leads to my first guideline when writing parallel code: Partition your problem into enough tasks to keep each processor busy throughout the operation, but not more than necessary to keep each processor busy. Also note that I parallelized the outer loop.  I could have just as easily partitioned the inner loop.  However, partitioning the inner loop would have led to many more discrete work items, each with a smaller amount of work (operate on one pixel instead of one row of pixels).  My second guideline when writing parallel code reflects this: Partition your problem in a way to place the most work possible into each task. This typically means, in practice, that you will want to parallelize the routine at the “highest” point possible in the routine, typically the outermost loop.  If you’re looking at parallelizing methods which call other methods, you’ll want to try to partition your work high up in the stack – as you get into lower level methods, the performance impact of parallelizing your routines may not overcome the overhead introduced. Parallel.For works great for situations where we know the number of elements we’re going to process in advance.  If we’re iterating through an IList<T> or an array, this is a typical approach.  However, there are other iteration statements common in C#.  In many situations, we’ll use foreach instead of a for loop.  This can be more understandable and easier to read, but also has the advantage of working with collections which only implement IEnumerable<T>, where we do not know the number of elements involved in advance. As an example, lets take the following situation.  Say we have a collection of Customers, and we want to iterate through each customer, check some information about the customer, and if a certain case is met, send an email to the customer and update our instance to reflect this change.  Normally, this might look something like: foreach(var customer in customers) { // Run some process that takes some time... DateTime lastContact = theStore.GetLastContact(customer); TimeSpan timeSinceContact = DateTime.Now - lastContact; // If it's been more than two weeks, send an email, and update... if (timeSinceContact.Days > 14) { theStore.EmailCustomer(customer); customer.LastEmailContact = DateTime.Now; } } Here, we’re doing a fair amount of work for each customer in our collection, but we don’t know how many customers exist.  If we assume that theStore.GetLastContact(customer) and theStore.EmailCustomer(customer) are both side-effect free, thread safe operations, we could parallelize this using Parallel.ForEach: Parallel.ForEach(customers, customer => { // Run some process that takes some time... DateTime lastContact = theStore.GetLastContact(customer); TimeSpan timeSinceContact = DateTime.Now - lastContact; // If it's been more than two weeks, send an email, and update... if (timeSinceContact.Days > 14) { theStore.EmailCustomer(customer); customer.LastEmailContact = DateTime.Now; } }); Just like Parallel.For, we rework our loop into a method call accepting a delegate created via a lambda expression.  This keeps our new code very similar to our original iteration statement, however, this will now execute in parallel.  The same guidelines apply with Parallel.ForEach as with Parallel.For. The other iteration statements, do and while, do not have direct equivalents in the Task Parallel Library.  These, however, are very easy to implement using Parallel.ForEach and the yield keyword. Most applications can benefit from implementing some form of Data Parallelism.  Iterating through collections and performing “work” is a very common pattern in nearly every application.  When the problem can be decomposed by data, we often can parallelize the workload by merely changing foreach statements to Parallel.ForEach method calls, and for loops to Parallel.For method calls.  Any time your program operates on a collection, and does a set of work on each item in the collection where that work is not dependent on other information, you very likely have an opportunity to parallelize your routine.

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  • Java 2D Game Frameworks

    - by Software Monkey
    I have been looking at frameworks for writing 2D games in Java - part of a growing desire to rediscover my roots in writing those simple but addictive video games. I have googled and found some possibilities, but it's hard to judge which is best without investing significant time in each. Does anyone out there have any recommendations from experience, preferably with a list of pro's and con's for the framework. NOTE: I am not looking so much for comparisons between frameworks but, rather, feedback on any given framework from actually having used it firsthand, or knowing someone who has. The other possibility I am considering is rolling my own, but would rather not. EDIT: I am targeting Java on the Desktop, and expect capable machines, though not state of the art. Some of the 2D engines I have found: Free PulpCore (License: BSD) Slick2D (License: BSD) GTGE - Golden T Game Engine JGame GAGE - Genuine Advantage Gaming Engine GameFrame for Java Basilisk (2D and 3D) Free for non-commercial use Genuts EasyWay - a high-level 2D engine

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  • What tools provide burndown charts to Bugzilla or Mylyn?

    - by Daniel Jomphe
    My team and I need to work on a project whose bugs are filed in Bugzilla, using Mylyn. Do you know of any tool or plug-in that provides scrum-inspired burndown charts to Bugzilla or Mylyn? Hopefully, this tool would be free for commercial usage, but we're not closed to commercial tools. Update: 4 hours of research allowed me to find very few free tools. Looks like bugzilla isn't popular in agile teams! And obviously, it's not the best fit.

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  • List of freely available programming books

    - by Karan Bhangui
    I'm trying to amass a list of programming books with opensource licenses, like Creative Commons, GPL, etc. The books can be about a particular programming language or about computers in general. Hoping you guys could help: Languages BASH Advanced Bash-Scripting Guide (An in-depth exploration of the art of shell scripting) C The C book C++ Thinking in C++ C++ Annotations How to Think Like a Computer Scientist C# .NET Book Zero: What the C or C++ Programmer Needs to Know About C# and the .NET Framework Illustrated C# 2008 (Dead Link) Data Structures and Algorithms with Object-Oriented Design Patterns in C# Threading in C# Common Lisp Practical Common Lisp On Lisp Java Thinking in Java How to Think Like a Computer Scientist Java Thin-Client Programming JavaScript Eloquent JavaScript Haskell Real world Haskell Learn You a Haskell for Great Good! Objective-C The Objective-C Programming Language Perl Extreme Perl (license not specified - home page is saying "freely available") The Mason Book (Open Publication License) Practical mod_perl (CreativeCommons Attribution Share-Alike License) Higher-Order Perl Learning Perl the Hard Way PHP Practical PHP Programming Zend Framework: Survive the Deep End PowerShell Mastering PowerShell Prolog Building Expert Systems in Prolog Adventure in Prolog Prolog Programming A First Course Logic, Programming and Prolog (2ed) Introduction to Prolog for Mathematicians Learn Prolog Now! Natural Language Processing Techniques in Prolog Python Dive Into Python Dive Into Python 3 How to Think Like a Computer Scientist A Byte of Python Python for Fun Invent Your Own Computer Games With Python Ruby Why's (Poignant) Guide to Ruby Programming Ruby - The Pragmatic Programmer's Guide Mr. Neighborly's Humble Little Ruby Book SQL Practical PostgreSQL x86 assembly Paul Carter's tutorial Lua Programming In Lua (for v5 but still largely relevant) Algorithms and Data Structures Algorithms Data Structures and Algorithms with Object-Oriented Design Patterns in Java Planning Algorithms Frameworks/Projects The Django Book The Pylons Book Introduction to Design Patterns in C++ with Qt 4 (Open Publication License) Version control The SVN Book Mercurial: The Definitive Guide Pro Git UNIX / Linux The Art of Unix Programming Linux Device Drivers, Third Edition Others Structure and Interpretation of Computer Programs The Little Book of Semaphores Mathematical Logic - an Introduction An Introduction to the Theory of Computation Developers Developers Developers Developers Linkers and loaders Beej's Guide to Network Programming Maven: The Definitive Guide I will expand on this list as I get comments or when I think of more :D Related: Programming texts and reference material for my Kindle What are some good free programming books? Can anyone recommend a free software engineering book? Edit: Oh I didn't notice the community wiki feature. Feel free to edit your suggestions right in!

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  • Question about the MIT License and open/closed source

    - by stck777
    Hallo, I have a small useful application (Websites managment tool developed in Java) which I want to publish online for free (every one can use it for free). But I do not want to make it opne source yet. It is additional affort to clean up the code, documantation and so on... And this is just a small useful tool. Can I use the MIT license in this case, or the MIT license obligates me to distribute the source code? Which license is best in this case? Thanks.

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  • PostgreSQL / Ruby for commercial application

    - by RPK
    I am planning a web-based commercial application with front-end RoR and back-end PostgreSQL. I've some confusion about RoR and PostgreSQL Edition to use. For RoR, I have Aptana RADRails installed. For PostgreSQL, a free variant is also available at EnterpriseDB. Previously I installed a free EnterpriseDB PostgreSQL variant and it was very smooth and had professional touch. It was quite different from the one available from PostgreSQL website. I want to know which IDE and RoR variant to use for my project. I have no idea of Ruby and Rails. I will be learning and developing simultaneously. Also, which PostgreSQL variant to use? Can these two technologies be used for a developing a commercial application?

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  • CKeditor integration with FCKeditor filebrowser

    - by -provideralexander.rios
    Hi everybody. I'm using CKeditor 3 and I need integrate a filebrowser/uploader. It need to be free. I tried to integrate the one what come with FCKeditor but I allways got and xml error: http://pastie.org/743024 I'm trying to do it in this way: <script type="text/javascript"> window.onload = function(){ CKEDITOR.config.language='es'; CKEDITOR.config.forcePasteAsPlainText = true; CKEDITOR.config.enterMode = CKEDITOR.ENTER_DIV; CKEDITOR.replace('ncCont',{ filebrowserBrowseUrl: 'filemanager/browser/default/browser.html', filebrowserUploadUrl : 'filemanager/connectors/php/upload.php' }); }; </script> Can the FCKeditor get integrated with CKeditor?? if yes, how this can get done? if don't, knows somebody a free filebrowser/uploader?? Thanks in advance.

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  • SOA Suite Integration: Part 2: A basic BPEL process

    - by Anthony Shorten
    This is the next in the series about SOA Suite integration with Oracle Utilities Application Framework. One of the first scenarios I am going to illustrate in this series is building a basic BPEL process using Web Service calls to the Oracle Utilities Application Framework. The scenario is this. I will pass in the userid and the BPEL process will call our the AS-User Web Service we created in Part 1. This is just a basic test and illustrate how to import the Web Service into SOA Suite. To use this scenario, you will need access to Oracle SOA Suite, access to a copy of any Oracle Utilities Application Framework based product and Oracle JDeveloper (to build the process). First of all you need to start Oracle JDeveloper and create a new SOA Project to house the BPEL process in. For the purposes of this example I will call the project simpleBPEL and verify that SOA is part of the project. I will select "Composite with BPEL" to denote it as a BPEL process. I can also the same process to create a Mediator or OSB project (refer to the JDeveloper documentation on these technologies). For this example I will use BPEL 1.1 as my specification standard (BPEL 2.0 can also be used if desired). I give the individual BPEL process as simpleBPEL (you can use a different name but I wanted to keep the project and process the same for this example). I will also build a Synchronous BPEL Process as I want a response from the Web Service. I will leave the defaults to save time. I have no have a blank canvas to build my BPEL process against. Note: for simplicity I am going to use as much defaulting as possible. In fact I am not going to specify an input schema for the incoming call as I will use the basic single field used by BPEL as default. The first step is to import the AS-User Web Service into my BPEL project. To do this I use the standard Web Service BPEL component from the Component Palette to import the WSDL into the BPEL project. Now the tricky part (a joke), you drag and drop the component from the Palette onto the right side of the canvas in the Partner Links swim lane. This swim lane is reserved for Partner Links that have a Partner Role (i.e. being called rather than calling). When you drop the Web Service onto the canvas the Create Web Service wizard is invoked to ask for details of the Web Service. At this point you give the BPEL node a name. I have used the name RetrieveUser as a name. I placed the WSDL URL from the XAI Inbound Service screen in the WSDL URL. Once you specify the URL you can press the Find existing WSDL's button to load the information into BPEL from the call. You will notice the Port Type is prefilled with the port from the WSDL. I also suggest that you check copy wsdl and it's dependent artifacts into the project if you intending to work on the BPEL process offline. If you do not check this your target application must be accessible when you work on the BPEL process (that is not always convenient). Note: For the perceptive of you will notice that the URL specified in this example is different to the URL in the last post. The reason is for the demonstrations I shifted to a new server and did not redo all of the past screen captures. If you copy the WSDL into the project you will get an information screen about Localize Files. It is just a confirmation screen. The last confirmation screen is a summary of the partner link (the main tab is locked for editing at this stage). At this stage you have successfully imported the Web Service. To complete the setup of the Web Service you need to set the credentials for the Web Service to use. Refer to the past post on how to do that. Now to use the Web Service. To call the Web Service (as it is just imported not connected to the BPEL process yet), you must add an Invoke action to your BPEL Process. To do this, select Invoke action from the BPEL Constructs zone on the Component Palette and drop it on the edit nodes between the receiveInput and replyOutput nodes This will create an empty Invoke action. You will notice some connectors on the Invoke node. Grab the node closest to your Web Service and drag it to connect the Invoke to your Web Service. This instructs BPEL to use the Invoke to call the Web Service. Once the Invoke action is connected to the Web Service an Edit Invoke edit dialog is displayed. At this point I suggest you name the Invoke node. It is important to name the nodes straightaway and name them appropriately for you to trace the logic. I used InvokeUser as the name in this example. To complete the node configuration you must create Variables to hold the input and output for the call. To do this clock on Automatically Create Input Variable on the Edit Invoke dialog. You will be presented with a default variable name. It uses the node name (that is why it is important to name the node before hitting this button) as a prefix. You can name the variable anything but I usually take the default. Repeat the same for the output variable. You now have a completed node for invoking the service. You have a very basic BPEL process which contains an input, invoke and output node. It is not complete yet though. You need to tell the BPEL process how to pass data from the input to the invoke step and how to take the output from the service call and pass it back to the service. You need to now add an Assign node to assign the input to the Web Service. To do this select Assign activity from BPEL Constructs zone in the Component Palette. Drag and drop the Assign activity between the receiveInput and InvokeUser nodes as you want to pass data between these two nodes. You have now added a new Assign node to your BPEL process Double clicking the node allows you to specify the name of the node. I use AssignUser to describe that I am assigning user data. On the Copy Rules tab you can specify the mapping between the input variable InputVariable/payload/process/input string and the input variable for the Web Service call. We are passing data from the input to BPEL to the relevant input variable on the Web Service. This is simply drag and drop between the two data structures. In the example, I am using the input to pass to the user element in my Web Service as the user is the primary key for the object. The fields become linked (which means data from source will be copied to target). Almost there. You now need to process the output from the Web Service call to the outputVariable of the client call. I have decided to pass back one piece of data, the name associated with the user by concatenating the firstName and lastName elements from the Web Service call. To do this I will use a Transform as it is not just a matter of an Assign action. It is a concatenation operation. This also illustrates how you can use BPEL functionality to transform data from a Web Service call. As with the other components you drag and drop the Transform component to the appropriate place in the BPEL process. In this case we want to transform the output from the Web Service call so we want it after the InvokeUser action and the replyOutput action. The Transform component is actually part of the Oracle Extensions to the BPEL specification. Double clicking the Transform node will allow you to name the node.  In this example I used TransformName. To complete the transform I need to tell the product the source of the transformation and the target of the transform. In the example this is the InvokeUser output variable. I also named the mapper file to TransformName. By clicking the + or pencil icon next to the map I can create the map. The mapping screen is shows the source and target schemas for me to map across. As with the assign I can map the relevant elements. In my example, I first map the firstName from the Web Service to the result element. As I want to concatenate the names, I drop the concat function on the call line. I now attach the last name to the function to indicate the concatenation of the field. By default the names will be concatenated with no space. To make the name legible I add a space between the field by clicking the function and adding a space in the call. I now have a completed mapping. I can now save the whole project as my BPEL process is now complete. As you can see the following happens: We accept input from the client (the userid for the call) in the receiveInput step. We assign that value to the input parameters for the Web Service call in the AssignUser step. We invoke the Web Service call to retrieve the data from the product in the InvokeUser step. We take the output from the InvokeUser step and concatenate the names in the TransformName step. We pass back the data in the replyOutput step. At this point we can deploy the BPEL process to the SOA Suite server. I will not cover this aspect as it really all SOA Suite specific (it is all done via Oracle JDeveloper). Now we need to test the service in SOA Suite. We will use the Fusion Middleware Control test facility. I will assume that credentials have also been setup as per our previous post (else you will get a 401 error). You navigate to the deployed BPEL process within Fusion Middleware Control and select the Test Service option. Specify some test data on the payload at the bottom of the Test Service screen. In my case I am returning my own userid information. On the response tab you will see the result. It works. You can verify the steps using the Audit trace facility on individual calls. As you can see this is a basic BPEL but you get the idea of importing the Web Service is pretty straightforward. You can create more sophisticated BPEL processes using the full facilities in Oracle SOA Suite. I just showed you the basic principals.

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  • Online Perforce Repositories

    - by Oliver Hume
    Is anyone aware of of anybody offering hosted perforce servers? It doesn't have to be free - but preferably not too expensive! My understanding of Perforce is that it's free to use for personal projects, which mine is. Currently I have a perforce server setup on the same machine as the code is on which doesn't offer much security in case of computer failure. If not, can anyone recommend one of the alternative solutions that is similar to Perforce? I have experience of SVN but cannot say I enjoy the experience.

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  • Pure C# open source PCM to Ogg convertor?

    - by Ole Jak
    Microsoft Silverlight 4 is in beta. It supports PCM audio output. It would be madness to stream PCM over internet (for ex in P2P chart webApp) so we need Pure C# open source PCM to Ogg convertor. No unmanaged code, nothing going out of .net sandbox. So does any one know such Pure C# open source PCM to Ogg convertor? What do I need: Open Source Libs for encoding. Tutorials and blog articles on How to do it, about etc. BTW: why Pure C#? - because Silverlight 4 does not support unmanaged or just not C# DLL's. BTW2: this question is similar to this one but it is different because Ogg is Open Source, free while mp3 will not be free until 2010

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  • 24 hours per day and freelance programming jobs

    - by Luca
    I'm working on stimulanting projects at my job. I like it. I like programming! I have accumulated several years of experience now. Sometime happens I develop other projects (even more stimulant of my main job). Some more money cannot hurts! The problem is that my free time has decreased a lot, leading me to develop until late evening. I usually program each day (I like to develop my own projects, even if only a few lines at a time). But it is one thing to plan for my pleasure, it is one thing to plan for business. So, my question is how to balance free time with these additional jobs? What experiences do you have? How much you can develop for long time (in a medium interval, say, weeks)? Every thought is welcome!

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  • Begin the Clone Wars Have!

    - by Antony Reynolds
    Creating a New Virtual Machine from an Existing Virtual Disk In previous posts I described how I set up an OEL6 machine under VirtualBox that can run an 11gR2 database and FMW 11.1.1.5.  That is great if you want the DB and FMW running in the same virtual image and it has served me well for some proof of concepts and also for some testing of different JVMs.  However I also wanted to run some testing of FMW with the database running on a separate physical machine.  So in this post I will show how to take a VirtualBox image and create a new image based on the disks from that original image. What are my Options? There is more than one way to skin a cat, or in this case to create two separate VMs that can run on different hardware.  Some of the options include: Create new virtual disk images for each new VM. Clone the existing disk images and point the new VM at the cloned images. Point the new VM at the existing snapshots. #1 is too much like hard work, install OEL twice, install a database again, install FMW again, run RCU again!  Life is too short! #2 is probably the safest way of doing things.  VirtualBox allows you to clone a disk image for use in a separate machine.  However this of course duplicates the disk and means that it is now occupying 3 times the space, once for the original disk and twice more for the two clones I would need. #3 is the most space efficient way of doing things.  It does mean however that I can only run the new “cloned” images if I have access to the original image because that is where the base snapshots reside.  However this is not a problem for me as long as I remember to keep all threee images together.  So this is the approach we will follow. Snapshot, What Snapshot? As we are going to create new virtual machines based on existing snapshots we need to figure out which snapshot to use.  We do this by opening the “Media Manager” from within VirtualBox and moving the mouse over the snapshot images until we find the snapshots we want – the snapshot name is identified in the “Attached to:” comment.  In my case I wanted the FMW installed snapshot because that had a database configured for FMW alongside the FMW software.  I made a note of the filename of that snapshot (actually I just noted the first 5 characters as that was all that was needed to uniquely identify the snapshot file). When we create the new machines we will point them at the snapshot filename we have just checked. Network or NotWork? Because we want the two new machines to communicate with each other when hosted in different physical machines we can’t use the default NAT networking mode without a lot of hassle.  But at the same time we need them to have fixed IP addresses relative to each other so that they can see each other whilst also being able to see the outside world. To achieve all these requirements I created two network adapters for each machine.  Adapter 1 was a standard NAT mapping.  This will allow each machine to get a dynamic IP address (10.0.2.15 by default) that can be used to access the external world through the VBox provided NAT gateway.  This is the same as the existing configuration. The second adapter I created as a bridged adapter.  This gives the virtual machine direct access to the host network card and by using fixed IP addresses each machine can see the other.  It is important to choose fixed IP addresses that are not routable across your internal network so you don’t get any clashes with other machines on your network.  Of course you could always get proper fixed IP addresses from your network people, but I have serveral people using my images and as long as I don’t have two instances of the same VM on the same network segment this is easier and avoids reconfiguring the network every time someone wants a copy of my VM.  If it is available I would suggest using the 10.0.3.* network as 10.0.2.* is the default NAT network.  You can check availability by pinging 10.0.3.1 and 10.0.3.2 from your host machine.  If it times out then you are probably safe to use that. Creating the New VMs Now that I had collected the data that I needed I went ahead and created the new VMs. When asked for a “Boot Hard Disk” I used the “Choose a virtual hard disk file…” link to find the snapshot I had previously selected and set that to be the existing hard disk.  I chose the previously existing SOA 11.1.1.5 install for both the new DB and FMW machines because that snapshot had the database with the RCU completed that I wanted for my DB machine and it had the SOA software installed which I wanted for my FMW machine. After the initial creation of the virtual machine go into the network setting section and enable a second adapter which will be bridged.  Make a note of the MAC addresses (the last four digits should be sufficient) of the two adapters so that you can later set the bridged adapter to use fixed IP and the NAT adapter to use DHCP. We are now ready to start the VMs and reconfigure Linux. Reconfiguring Linux Because I now have two new machines I need to change their network configuration.  In particular I need to change the hostname, update the hosts file and change the network settings. Changing the Hostname I renamed both hosts by running the hostname command as root: hostname vboxfmw.oracle.com I also edited the /etc/sysconfig file and set the correct hostname in there. HOSTNAME=vboxfmw.oracle.com Changing the Network Settings I needed to change the network configuration to give the bridged network a fixed IP address.  I first explicitly set the MAC addresses of the two adapters, because the order of the virtual adapters in the VirtualBox Manager is not necessarily the same as the order of the adapters in the guest OS.  So I went in to the System->Preferences->Network Connections screen and explicitly set the “Device MAC address” for the two adapters. Having correctly mapped the Linux adapters to the VirtualBox adapters I then set the Bridged adapter to use fixed IP addressing rather than DHCP.  There is no need for additional routing or default gateways because we expect the two machine to be on the same LAN segment. Updating the Hosts File Having renamed the machines and reconfigured the network I then updated the /etc/hosts file to refer to the new machine name add a new line to the hosts file to provide an additional IP address for my server (the new fixed IP address) add a new line for the fixed IP address of the other virtual machine 10.0.3.101      vboxdb.oracle.com       vboxdb  # Added by NetworkManager 10.0.2.15       vboxdb.oracle.com       vboxdb  # Added by NetworkManager 10.0.3.102      vboxfmw.oracle.com      vboxfmw # Added by NetworkManager 127.0.0.1       localhost.localdomain   localhost ::1     vboxdb.oracle.com       vboxdb  localhost6.localdomain6 localhost6 To make sure everything takes effect I restarted the server. Reconfiguring the Database on the DB Machine Because we changed the hostname the listener and the EM console no longer start so I need to modify the listener.ora to use the new hostname and I also need to rebuild the EM configuration because it also relies on the hostname. I edited the $ORACLE_HOME/network/admin/listener.ora and changed the listening address to the new hostname:       (ADDRESS = (PROTOCOL = TCP)(HOST = vboxdb.oracle.com)(PORT = 1521)) After changing the listener.ora I was able to start the listener using: lsnrctl start I also had to reconfigure the EM database control.  I first deconfigured it using the command: emca -deconfig dbcontrol db -repos drop This drops the repository and removes any existing registered dbcontrols. I then re-configured it using the following command: emca -config dbcontrol db -repos create This creates the EM repository and then configures and starts dbcontrol. Now my database machine is ready so I can close it down and take a snapshot. Disabling the Database on the FMW Machine I set up the database to start automatically by creating a service called “dbora”.  On the FMW machine I do not need the database running so I can prevent it auto-starting by running the following command: chkconfig –del dbora Note that because I am using a snapshot it is not a waste of disk space to have the DB installed but not used.  As long as I don’t run it, it won’t cost me anything. I can now close the FMW machine down and take a snapshot. Creating a New Domain The FMW machine is now ready to create a new domain.  When creating the domain I can point it at the second machine which is running the database.  I can potentially run these machines on two separate physical machines as long as I have the original virtual machine available to both of the physical machines. Gotchas in Snapshotting VirtualBox does not support the concept of linked machines in a network like some virtualization technologies so when creating a snapshot it is a good idea to shut both VMs down and then take a snapshot on both of them.  This is because we want to keep the database in sync with the middleware.  One way to make sure that this happens would be to place all the domain configuration files on the database server via an NFS share, this would mean that all we would need to snapshot would be the database machine because that would hold all the state and configuration. The Sky’s the Limit We have covered a simple case of having just two machines.  I have a more complicated configuration in which two machine run a RAC database off the same base OS image, and two more machines run a SOA cluster based on the same OS image.  Just remember what machine holds state and what are the consequences of taking a snapshot.

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