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• Cocos2d-xna memory management for WP8

  - by Arkiliknam

  I recently upgraded to VS2012 and try my in dev game out on the new WP8 emulators but was dismayed to find out the emulator now crashes and throws an out of memory exception during my sprite loading procedure (funnily, it still works in WP7 emulators and on my WP7). Regardless of whether the problem is the emulator or not, I want to get a clear understanding of how I should be managing memory in the game. My game consists of a character whom has 4 or more different animations. Each animation consists of 4 to 7 frames. On top of that, the character has up to 8 stackable visualization modifications (eg eye type, nose type, hair type, clothes type). Pre memory issue, I preloaded all textures for each animation frame and customization and created animate action out of them. The game then plays animations using the customizations applied to that current character. I re-looked at this implementation when I received the out of memory exceptions and have started playing with RenderTexture instead, so instead of pre loading all possible textures, it on loads textures needed for the character, renders them onto a single texture, from which the animation is built. This means the animations use 1/8th of the sprites they were before. I thought this would solve my issue, but it hasn't. Here's a snippet of my code: var characterTexture = CCRenderTexture.Create((int)width, (int)height); characterTexture.BeginWithClear(0, 0, 0, 0); // stamp a body onto my texture var bodySprite = MethodToCreateSpecificSprite(); bodySprite.Position = centerPoint; bodySprite.Visit(); bodySprite.Cleanup(); bodySprite = null; // stamp eyes, nose, mouth, clothes, etc... characterTexture.End(); As you can see, I'm calling CleanUp and setting the sprite to null in the hope of releasing the memory, though I don't believe this is the right way, nor does it seem to work... I also tried using SharedTextureCache to load textures before Stamping my texture out, and then clearing the SharedTextureCache with: CCTextureCache.SharedTextureCache.RemoveAllTextures(); But this didn't have an effect either. Any tips on what I'm not doing? I used VS to do a memory profile of the emulation causing the crash. Both WP7.1 and WP8 emulators peak at about 150mb of usage. WP8 crashes and throws an out of memory exception. Each customisation/frame is 15kb at the most. Lets say there are 8 layers of customisation = 120kb but I render then onto one texture which I would assume is only 15kb again. Each animation is 8 frames at the most. That's 15kb for 1 texture, or 960kb for 8 textures of customisation. There are 4 animation sets. That's 60Kb for 4 sets of 1 texture, or 3.75MB for 4 sets of 8 textures of customisation. So even if its storing every layer, its 3.75MB.... no where near the 150mb breaking point my profiler seems to suggest :( WP 7.1 Memory Profile (max 150MB) WP8 Memory Profile (max 150MB and crashes)

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• Programação paralela no .NET Framework 4 – Parte I

  - by anobre

  Introdução O avanço de tecnologia nos últimos anos forneceu, a baixo custo, acesso  a workstations com inúmeros CPUs. Facilmente encontramos hoje máquinas clientes com 2, 4 e até 8 núcleos, sem considerar os “super-servidores” com até 36 processadores :) Da wikipedia: A Unidade central de processamento (CPU, de acordo com as iniciais em inglês) ou o processador é a parte de um sistema de computador que executa as instruções de um programa de computador, e é o elemento primordial na execução das funções de um computador. Este termo tem sido usado na indústria de computadores pelo menos desde o início dos anos 1960[1]. A forma, desenho e implementação de CPUs têm mudado dramaticamente desde os primeiros exemplos, mas o seu funcionamento fundamental permanece o mesmo. Fazendo uma analogia, seria muito interessante delegarmos tarefas no mundo real que podem ser executadas independentemente a pessoas diferentes, atingindo desta forma uma  maior performance / produtividade na sua execução. A computação paralela se baseia na idéia que um problema maior pode ser dividido em problemas menores, sendo resolvidos de forma paralela. Este pensamento é utilizado há algum tempo por HPC (High-performance computing), e através das facilidades dos últimos anos, assim como a preocupação com consumo de energia, tornaram esta idéia mais atrativa e de fácil acesso a qualquer ambiente. No .NET Framework A plataforma .NET apresenta um runtime, bibliotecas e ferramentas para fornecer uma base de acesso fácil e rápido à programação paralela, sem trabalhar diretamente com threads e thread pool. Esta série de posts irá apresentar todos os recursos disponíveis, iniciando os estudos pela TPL, ou Task Parallel Library. Task Parallel Library A TPL é um conjunto de tipos localizados no namespace System.Threading e System.Threading.Tasks, a partir da versão 4 do framework. A partir da versão 4 do framework, o TPL é a maneira recomendada para escrever código paralelo e multithreaded. http://msdn.microsoft.com/en-us/library/dd460717(v=VS.100).aspx Task Parallelism O termo “task parallelism”, ou em uma tradução live paralelismo de tarefas, se refere a uma ou mais tarefas sendo executadas de forma simultanea. Considere uma tarefa como um método. A maneira mais fácil de executar tarefas de forma paralela é o código abaixo: Parallel.Invoke(() => TrabalhoInicial(), () => TrabalhoSeguinte()); O que acontece de verdade? Por trás nos panos, esta instrução instancia de forma implícita objetos do tipo Task, responsável por representar uma operação assíncrona, não exatamente paralela: public class Task : IAsyncResult, IDisposable É possível instanciar Tasks de forma explícita, sendo uma alternativa mais complexa ao Parallel.Invoke. var task = new Task(() => TrabalhoInicial()); task.Start(); Outra opção de instanciar uma Task e já executar sua tarefa é: var t = Task<int>.Factory.StartNew(() => TrabalhoInicialComValor());var t2 = Task<int>.Factory.StartNew(() => TrabalhoSeguinteComValor()); A diferença básica entre as duas abordagens é que a primeira tem início conhecido, mais utilizado quando não queremos que a instanciação e o agendamento da execução ocorra em uma só operação, como na segunda abordagem. Data Parallelism Ainda parte da TPL, o Data Parallelism se refere a cenários onde a mesma operação deva ser executada paralelamente em elementos de uma coleção ou array, através de instruções paralelas For e ForEach. A idéia básica é pegar cada elemento da coleção (ou array) e trabalhar com diversas threads concomitantemente. A classe-chave para este cenário é a System.Threading.Tasks.Parallel // Sequential version foreach (var item in sourceCollection) { Process(item); } // Parallel equivalent Parallel.ForEach(sourceCollection, item => Process(item)); Complicado né? :) Demonstração Acesse aqui um vídeo com exemplos (screencast). Cuidado! Apesar da imensa vontade de sair codificando, tome cuidado com alguns problemas básicos de paralelismo. Neste link é possível conhecer algumas situações. Abraços.

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• Parallelism in .NET – Part 19, TaskContinuationOptions

  - by Reed

  My introduction to Task continuations demonstrates continuations on the Task class.  In addition, I’ve shown how continuations allow handling of multiple tasks in a clean, concise manner.  Continuations can also be used to handle exceptional situations using a clean, simple syntax. In addition to standard Task continuations , the Task class provides some options for filtering continuations automatically.  This is handled via the TaskContinationOptions enumeration, which provides hints to the TaskScheduler that it should only continue based on the operation of the antecedent task. This is especially useful when dealing with exceptions.  For example, we can extend the sample from our earlier continuation discussion to include support for handling exceptions thrown by the Factorize method: // Get a copy of the UI-thread task scheduler up front to use later var uiScheduler = TaskScheduler.FromCurrentSynchronizationContext(); // Start our task var factorize = Task.Factory.StartNew( () => { int primeFactor1 = 0; int primeFactor2 = 0; bool result = Factorize(10298312, ref primeFactor1, ref primeFactor2); return new { Result = result, Factor1 = primeFactor1, Factor2 = primeFactor2 }; }); // When we succeed, report the results to the UI factorize.ContinueWith(task => textBox1.Text = string.Format("{0}/{1} [Succeeded {2}]", task.Result.Factor1, task.Result.Factor2, task.Result.Result), CancellationToken.None, TaskContinuationOptions.NotOnFaulted, uiScheduler); // When we have an exception, report it factorize.ContinueWith(task => textBox1.Text = string.Format("Error: {0}", task.Exception.Message), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, uiScheduler); .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; } The above code works by using a combination of features.  First, we schedule our task, the same way as in the previous example.  However, in this case, we use a different overload of Task.ContinueWith which allows us to specify both a specific TaskScheduler (in order to have your continuation run on the UI’s synchronization context) as well as a TaskContinuationOption.  In the first continuation, we tell the continuation that we only want it to run when there was not an exception by specifying TaskContinuationOptions.NotOnFaulted.  When our factorize task completes successfully, this continuation will automatically run on the UI thread, and provide the appropriate feedback. However, if the factorize task has an exception – for example, if the Factorize method throws an exception due to an improper input value, the second continuation will run.  This occurs due to the specification of TaskContinuationOptions.OnlyOnFaulted in the options.  In this case, we’ll report the error received to the user. We can use TaskContinuationOptions to filter our continuations by whether or not an exception occurred and whether or not a task was cancelled.  This allows us to handle many situations, and is especially useful when trying to maintain a valid application state without ever blocking the user interface.  The same concepts can be extended even further, and allow you to chain together many tasks based on the success of the previous ones.  Continuations can even be used to create a state machine with full error handling, all without blocking the user interface thread.

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• Converting Openfire IM datetime values in SQL Server to / from VARCHAR(15) and DATETIME data types

  - by Brian Biales

  A client is using Openfire IM for their users, and would like some custom queries to audit user conversations (which are stored by Openfire in tables in the SQL Server database). Because Openfire supports multiple database servers and multiple platforms, the designers chose to store all date/time stamps in the database as 15 character strings, which get converted to Java Date objects in their code (Openfire is written in Java).  I did some digging around, and, so I don't forget and in case someone else will find this useful, I will put the simple algorithms here for converting back and forth between SQL DATETIME and the Java string representation. The Java string representation is the number of milliseconds since 1/1/1970.  SQL Server's DATETIME is actually represented as a float, the value being the number of days since 1/1/1900, the portion after the decimal point representing the hours/minutes/seconds/milliseconds... as a fractional part of a day.  Try this and you will see this is true:     SELECT CAST(0 AS DATETIME) and you will see it returns the date 1/1/1900. The difference in days between SQL Server's 0 date of 1/1/1900 and the Java representation's 0 date of 1/1/1970 is found easily using the following SQL:   SELECT DATEDIFF(D, '1900-01-01', '1970-01-01') which returns 25567.  There are 25567 days between these dates. So to convert from the Java string to SQL Server's date time, we need to convert the number of milliseconds to a floating point representation of the number of days since 1/1/1970, then add the 25567 to change this to the number of days since 1/1/1900.  To convert to days, you need to divide the number by 1000 ms/s, then by  60 seconds/minute, then by 60 minutes/hour, then by 24 hours/day.  Or simply divide by 1000*60*60*24, or 86400000.   So, to summarize, we need to cast this string as a float, divide by 86400000 milliseconds/day, then add 25567 days, and cast the resulting value to a DateTime.  Here is an example:   DECLARE @tmp as VARCHAR(15)   SET @tmp = '1268231722123'   SELECT @tmp as JavaTime, CAST((CAST(@tmp AS FLOAT) / 86400000) + 25567 AS DATETIME) as SQLTime   To convert from SQL datetime back to the Java time format is not quite as simple, I found, because floats of that size do not convert nicely to strings, they end up in scientific notation using the CONVERT function or CAST function.  But I found a couple ways around that problem. You can convert a date to the number of  seconds since 1/1/1970 very easily using the DATEDIFF function, as this value fits in an Int.  If you don't need to worry about the milliseconds, simply cast this integer as a string, and then concatenate '000' at the end, essentially multiplying this number by 1000, and making it milliseconds since 1/1/1970.  If, however, you do care about the milliseconds, you will need to use DATEPART to get the milliseconds part of the date, cast this integer to a string, and then pad zeros on the left to make sure this is three digits, and concatenate these three digits to the number of seconds string above.  And finally, I discovered by casting to DECIMAL(15,0) then to VARCHAR(15), I avoid the scientific notation issue.  So here are all my examples, pick the one you like best... First, here is the simple approach if you don't care about the milliseconds:   DECLARE @tmp as VARCHAR(15)   DECLARE @dt as DATETIME   SET @dt = '2010-03-10 14:35:22.123'   SET @tmp = CAST(DATEDIFF(s, '1970-01-01 00:00:00' , @dt) AS VARCHAR(15)) + '000'   SELECT @tmp as JavaTime, @dt as SQLTime If you want to keep the milliseconds:   DECLARE @tmp as VARCHAR(15)   DECLARE @dt as DATETIME   DECLARE @ms as int   SET @dt = '2010-03-10 14:35:22.123'   SET @ms as DATEPART(ms, @dt)   SET @tmp = CAST(DATEDIFF(s, '1970-01-01 00:00:00' , @dt) AS VARCHAR(15))           + RIGHT('000' + CAST(@ms AS VARCHAR(3)), 3)   SELECT @tmp as JavaTime, @dt as SQLTime Or, in one fell swoop:   DECLARE @dt as DATETIME   SET @dt = '2010-03-10 14:35:22.123'   SELECT @dt as SQLTime     , CAST(DATEDIFF(s, '1970-01-01 00:00:00' , @dt) AS VARCHAR(15))           + RIGHT('000' + CAST( DATEPART(ms, @dt) AS VARCHAR(3)), 3) as JavaTime   And finally, a way to simply reverse the math used converting from Java date to SQL date. Note the parenthesis - watch out for operator precedence, you want to subtract, then multiply:   DECLARE @dt as DATETIME   SET @dt = '2010-03-10 14:35:22.123'   SELECT @dt as SQLTime     , CAST(CAST((CAST(@dt as Float) - 25567.0) * 86400000.0 as DECIMAL(15,0)) as VARCHAR(15)) as JavaTime Interestingly, I found that converting to SQL Date time can lose some accuracy, when I converted the time above to Java time then converted  that back to DateTime, the number of milliseconds is 120, not 123.  As I am not interested in the milliseconds, this is ok for me.  But you may want to look into using DateTime2 in SQL Server 2008 for more accuracy.

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• Grouping data in LINQ with the help of group keyword

  - by vik20000in

  While working with any kind of advanced query grouping is a very important factor. Grouping helps in executing special function like sum, max average etc to be performed on certain groups of data inside the date result set. Grouping is done with the help of the Group method. Below is an example of the basic group functionality.     int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };         var numberGroups =         from num in numbers         group num by num % 5 into numGroup         select new { Remainder = numGroup.Key, Numbers = numGroup };  In the above example we have grouped the values based on the reminder left over when divided by 5. First we are grouping the values based on the reminder when divided by 5 into the numgroup variable.  numGroup.Key gives the value of the key on which the grouping has been applied. And the numGroup itself contains all the records that are contained in that group. Below is another example to explain the same. string[] words = { "blueberry", "abacus", "banana", "apple", "cheese" };         var wordGroups =         from num in words         group num by num[0] into grp         select new { FirstLetter = grp.Key, Words = grp }; In the above example we are grouping the value with the first character of the string (num[0]). Just like the order operator the group by clause also allows us to write our own logic for the Equal comparison (That means we can group Item by ignoring case also by writing out own implementation). For this we need to pass an object that implements the IEqualityComparer<string> interface. Below is an example. public class AnagramEqualityComparer : IEqualityComparer<string> {     public bool Equals(string x, string y) {         return getCanonicalString(x) == getCanonicalString(y);     }      public int GetHashCode(string obj) {         return getCanonicalString(obj).GetHashCode();     }         private string getCanonicalString(string word) {         char[] wordChars = word.ToCharArray();         Array.Sort<char>(wordChars);         return new string(wordChars);     } }  string[] anagrams = {"from   ", " salt", " earn", "  last   ", " near "}; var orderGroups = anagrams.GroupBy(w => w.Trim(), new AnagramEqualityComparer()); Vikram  

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• Time to stop using &ldquo;Execute Package Task&rdquo;&ndash; a way to execute package in SSIS catalog taking advantage of the new project deployment model ,and the logging and reporting feature

  - by Kevin Shyr

  I set out to find a way to dynamically call package in SSIS 2012.  The following are 2 excellent blogs I found; I used them heavily.  The code below has some addition to parameter types and message types, but was made essentially derived entirely from the blogs. http://sqlblog.com/blogs/jamie_thomson/archive/2011/07/16/ssis-logging-in-denali.aspx http://www.ssistalk.com/2012/07/24/quick-tip-run-ssis-2012-packages-synchronously-and-other-execution-options/   The code: Every package will be called by a PackageController package.  The packageController is initialized with some information on which package to run and what information to pass in.   The following is the stored procedure called from the “Execute SQL Task”.  Here is the highlight of the stored procedure It takes in packageName, project name, and folder name (folder in SSIS project deployment to SSIS catalog) The stored procedure sets the package variables of the upcoming package execution Execute package in SSIS Catalog Get the status of the execution.  Also, if exists, get the error message’s message_id and store them in the management database. Return value to “Execute SQL Task” to manage failure properly CREATE PROCEDURE [AUDIT].[LaunchPackageExecutionInSSISCatalog]        @PackageName NVARCHAR(255)        , @ProjectFolder NVARCHAR(255)        , @ProjectName NVARCHAR(255)        , @AuditKey INT        , @DisableNotification BIT        , @PackageExecutionLogID INT AS BEGIN TRY        DECLARE @execution_id BIGINT = 0;        -- Create a package execution        EXEC [SSISDB].[catalog].[create_execution]                     @package_name=@PackageName,                     @execution_id=@execution_id OUTPUT,                     @folder_name=@ProjectFolder,                     @project_name=@ProjectName,                     @use32bitruntime=False;          UPDATE [AUDIT].[PackageInstanceExecutionLog] WITH(ROWLOCK)        SET [SSISCatalogExecutionID] = @execution_id        WHERE [PackageInstanceExecutionLogID] = @PackageExecutionLogID          -- this is to set the execution synchronized so that I can check the result in the end        EXEC [SSISDB].[catalog].[set_execution_parameter_value]                     @execution_id,                      @object_type=50,                     @parameter_name=N'SYNCHRONIZED',                     @parameter_value=1; -- true          /********************************************************         ********************************************************              Section: setting parameters                     Source table:  SSISDB.internal.object_parameters              object_type list:                     20: project level variables                     30: package level variables                     50: execution parameter         ********************************************************         ********************************************************/        EXEC [SSISDB].[catalog].[set_execution_parameter_value]                     @execution_id,                      @object_type=30,                     @parameter_name=N'FromParent_AuditKey',                     @parameter_value=@AuditKey; -- true          EXEC [SSISDB].[catalog].[set_execution_parameter_value]                     @execution_id,                      @object_type=30,                     @parameter_name=N'FromParent_DisableNotification',                     @parameter_value=@DisableNotification; -- true          EXEC [SSISDB].[catalog].[set_execution_parameter_value]                     @execution_id,                      @object_type=30,                     @parameter_name=N'FromParent_PackageInstanceExecutionID',                     @parameter_value=@PackageExecutionLogID; -- true        /********************************************************         ********************************************************              Section: setting variables END         ********************************************************         ********************************************************/            /* This section is carried over from example code           I don't see a reason to change them yet        */        -- Set our package parameters        EXEC [SSISDB].[catalog].[set_execution_parameter_value]                     @execution_id,                      @object_type=50,                     @parameter_name=N'DUMP_ON_EVENT',                     @parameter_value=1; -- true          EXEC [SSISDB].[catalog].[set_execution_parameter_value]                     @execution_id,                      @object_type=50,                     @parameter_name=N'DUMP_EVENT_CODE',                     @parameter_value=N'0x80040E4D;0x80004005';          EXEC [SSISDB].[catalog].[set_execution_parameter_value]                     @execution_id,                      @object_type=50,                     @parameter_name=N'LOGGING_LEVEL',                     @parameter_value= 1; -- Basic          EXEC [SSISDB].[catalog].[set_execution_parameter_value]                     @execution_id,                      @object_type=50,                     @parameter_name=N'DUMP_ON_ERROR',                     @parameter_value=1; -- true                              /********************************************************         ********************************************************              Section: EXECUTING         ********************************************************         ********************************************************/        EXEC [SSISDB].[catalog].[start_execution]                     @execution_id;        /********************************************************         ********************************************************              Section: EXECUTING END         ********************************************************         ********************************************************/            /********************************************************         ********************************************************              Section: checking execution result                     Source table:  [SSISDB].[catalog].[executions]              status:                     1: created                     2: running                     3: cancelled                     4: failed                     5: pending                     6: ended unexpectedly                     7: succeeded                     8: stopping                     9: completed         ********************************************************         ********************************************************/        if EXISTS(SELECT TOP 1 1                            FROM [SSISDB].[catalog].[executions] WITH(NOLOCK)                            WHERE [execution_id] = @execution_id                                  AND [status] NOT IN (2, 7, 9)) BEGIN                /********************************************************               ********************************************************                     Section: logging error messages                            Source table:  [SSISDB].[internal].[operation_messages]                     message type:                            10:  OnPreValidate                             20:  OnPostValidate                             30:  OnPreExecute                             40:  OnPostExecute                             60:  OnProgress                             70:  OnInformation                             90:  Diagnostic                             110:  OnWarning                            120:  OnError                            130:  Failure                            140:  DiagnosticEx                             200:  Custom events                             400:  OnPipeline                     message source type:                            10:  Messages logged by the entry APIs (e.g. T-SQL, CLR Stored procedures)                             20:  Messages logged by the external process used to run package (ISServerExec)                             30:  Messages logged by the package-level objects                             40:  Messages logged by tasks in the control flow                             50:  Messages logged by containers (For, ForEach, Sequence) in the control flow                             60:  Messages logged by the Data Flow Task                                    ********************************************************               ********************************************************/                INSERT INTO AUDIT.PackageInstanceExecutionOperationErrorLink                     SELECT @PackageExecutionLogID                                  ,[operation_message_id]                            FROM [SSISDB].[internal].[operation_messages] WITH(NOLOCK)                            WHERE operation_id = @execution_id                                  AND message_type IN (120, 130)                           EXEC [AUDIT].[FailPackageInstanceExecution] @PackageExecutionLogID, 'SSISDB Internal operation_messages found'                GOTO ReturnTrueAsErrorFlag                /********************************************************               ********************************************************                     Section: checking messages END               ********************************************************               ********************************************************/                /* This part is not really working, so now using rowcount to pass status              --DECLARE @PackageErrorMessage NVARCHAR(4000)              --SET @PackageErrorMessage = @PackageName + 'failed with executionID: ' + CONVERT(VARCHAR(20), @execution_id)                --RAISERROR (@PackageErrorMessage -- Message text.              --     , 18 -- Severity,              --     , 1 -- State,              --     , N'check table AUDIT.PackageInstanceExecutionErrorMessages' -- First argument.              --     );              */        END        ELSE BEGIN              GOTO ReturnFalseAsErrorFlagToSignalSuccess        END        /********************************************************         ********************************************************              Section: checking execution result END         ********************************************************         ********************************************************/ END TRY BEGIN CATCH        DECLARE @SSISCatalogCallError NVARCHAR(MAX)        SELECT @SSISCatalogCallError = ERROR_MESSAGE()          EXEC [AUDIT].[FailPackageInstanceExecution] @PackageExecutionLogID, @SSISCatalogCallError          GOTO ReturnTrueAsErrorFlag END CATCH;     /********************************************************  ********************************************************    Section: end result  ********************************************************  ********************************************************/ ReturnTrueAsErrorFlag:        SELECT CONVERT(BIT, 1) AS PackageExecutionErrorExists ReturnFalseAsErrorFlagToSignalSuccess:        SELECT CONVERT(BIT, 0) AS PackageExecutionErrorExists   GO

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• A Closer Look at the HiddenInput Attribute in MVC 2

  - by Steve Michelotti

  MVC 2 includes an attribute for model metadata called the HiddenInput attribute. The typical usage of the attribute looks like this (line #3 below): 1: public class PersonViewModel 2: { 3: [HiddenInput(DisplayValue = false)] 4: public int? Id { get; set; } 5: public string FirstName { get; set; } 6: public string LastName { get; set; } 7: } So if you displayed your PersonViewModel with Html.EditorForModel() or Html.EditorFor(m => m.Id), the framework would detect the [HiddenInput] attribute metadata and produce HTML like this: 1: <input id="Id" name="Id" type="hidden" value="21" /> This is pretty straight forward and allows an elegant way to keep the technical key for your model (e.g., a Primary Key from the database) in the HTML so that everything will be wired up correctly when the form is posted to the server and of course not displaying this value visually to the end user. However, when I was giving a recent presentation, a member of the audience asked me (quite reasonably), “When would you ever set DisplayValue equal to true when using a HiddenInput?” To which I responded, “Well, it’s an edge case. There are sometimes when…er…um…people might want to…um…display this value to the user.” It was quickly apparent to me (and I’m sure everyone else in the room) what a terrible answer this was. I realized I needed to have a much better answer here. First off, let’s look at what is produced if we change our view model to use “true” (which is equivalent to use specifying [HiddenInput] since “true” is the default) on line #3: 1: public class PersonViewModel 2: { 3: [HiddenInput(DisplayValue = true)] 4: public int? Id { get; set; } 5: public string FirstName { get; set; } 6: public string LastName { get; set; } 7: } Will produce the following HTML if rendered from Htm.EditorForModel() in your view: 1: <div class="editor-label"> 2: <label for="Id">Id</label> 3: </div> 4: <div class="editor-field"> 5: 21<input id="Id" name="Id" type="hidden" value="21" /> 6: <span class="field-validation-valid" id="Id_validationMessage"></span> 7: </div> The key is line #5. We get the text of “21” (which happened to be my DB Id in this instance) and also a hidden input element (again with “21”). So the question is, why would one want to use this? The best answer I’ve found is contained in this MVC 2 whitepaper: When a view lets users edit the ID of an object and it is necessary to display the value as well as to provide a hidden input element that contains the old ID so that it can be passed back to the controller. Well, that actually makes sense. Yes, it seems like something that would happen *rarely* but, for those instances, it would enable them easily. It’s effectively equivalent to doing this in your view: 1: <%: Html.LabelFor(m => m.Id) %> 2: <%: Model.Id %> 3: <%: Html.HiddenFor(m => m.Id) %> But it’s allowing you to specify it in metadata on your view model (and thereby take advantage of templated helpers like Html.EditorForModel() and Html.EditorFor()) rather than having to explicitly specifying everything in your view.

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• Using the StopWatch class to calculate the execution time of a block of code

  - by vik20000in

    Many of the times while doing the performance tuning of some, class, webpage, component, control etc. we first measure the current time taken in the execution of that code. This helps in understanding the location in code which is actually causing the performance issue and also help in measuring the amount of improvement by making the changes. This measurement is very important as it helps us understand the problem in code, Helps us to write better code next time (as we have already learnt what kind of improvement can be made with different code) . Normally developers create 2 objects of the DateTime class. The exact time is collected before and after the code where the performance needs to be measured.  Next the difference between the two objects is used to know about the time spent in the code that is measured. Below is an example of the sample code.             DateTime dt1, dt2;             dt1 = DateTime.Now;             for (int i = 0; i < 1000000; i++)             {                 string str = "string";             }             dt2 = DateTime.Now;             TimeSpan ts = dt2.Subtract(dt1);             Console.WriteLine("Time Spent : " + ts.TotalMilliseconds.ToString());   The above code works great. But the dot net framework also provides for another way to capture the time spent on the code without doing much effort (creating 2 datetime object, timespan object etc..). We can use the inbuilt StopWatch class to get the exact time spent. Below is an example of the same work with the help of the StopWatch class.             Stopwatch sw = Stopwatch.StartNew();             for (int i = 0; i < 1000000; i++)             {                 string str = "string";             }             sw.Stop();             Console.WriteLine("Time Spent : " +sw.Elapsed.TotalMilliseconds.ToString());   [Note the StopWatch class resides in the System.Diagnostics namespace] If you use the StopWatch class the time taken for measuring the performance is much better, with very little effort. Vikram

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• SQL SERVER – Solution of Puzzle – Swap Value of Column Without Case Statement

  - by pinaldave

  Earlier this week I asked a question where I asked how to Swap Values of the column without using CASE Statement. Read here: SQL SERVER – A Puzzle – Swap Value of Column Without Case Statement. I have proposed 3 different solutions in the blog posts itself. I had requested the help of the community to come up with alternate solutions and honestly I am stunned and amazed by the qualified entries. I will be not able to cover every single solution which is posted as a comment, however, I would like to for sure cover few interesting entries. However, I am selecting 5 solutions which are different (not necessary they are most optimal or best – just different and interesting). Just for clarity I am involving the original problem statement here. USE tempdb GO CREATE TABLE SimpleTable (ID INT, Gender VARCHAR(10)) GO INSERT INTO SimpleTable (ID, Gender) SELECT 1, 'female' UNION ALL SELECT 2, 'male' UNION ALL SELECT 3, 'male' GO SELECT * FROM SimpleTable GO -- Insert Your Solutions here -- Swap value of Column Gender SELECT * FROM SimpleTable GO DROP TABLE SimpleTable GO Here are the five most interesting and different solutions I have received. Solution by Roji P Thomas UPDATE S SET S.Gender = D.Gender FROM SimpleTable S INNER JOIN SimpleTable D ON S.Gender != D.Gender I really loved the solutions as it is very simple and drives the point home – elegant and will work pretty much for any values (not necessarily restricted by the option in original question ‘male’ or ‘female’). Solution by Aneel CREATE TABLE #temp(id INT, datacolumn CHAR(4)) INSERT INTO #temp VALUES(1,'gent'),(2,'lady'),(3,'lady') DECLARE @value1 CHAR(4), @value2 CHAR(4) SET @value1 = 'lady' SET @value2 = 'gent' UPDATE #temp SET datacolumn = REPLACE(@value1 + @value2,datacolumn,'') Aneel has very interesting solution where he combined both the values and replace the original value. I personally liked this creativity of the solution. Solution by SIJIN KUMAR V P UPDATE SimpleTable SET Gender = RIGHT(('fe'+Gender), DIFFERENCE((Gender),SOUNDEX(Gender))*2) Sijin has amazed me with Difference and Soundex function. I have never visualized that above two functions can resolve the problem. Hats off to you Sijin. Solution by Nikhildas UPDATE St SET St.Gender = t.Gender FROM SimpleTable St CROSS Apply (SELECT DISTINCT gender FROM SimpleTable WHERE St.Gender != Gender) t I was expecting that someone will come up with this solution where they use CROSS APPLY. This is indeed very neat and for sure interesting exercise. If you do not know how CROSS APPLY works this is the time to learn. Solution by mistermagooo UPDATE SimpleTable SET Gender=X.NewGender FROM (VALUES('male','female'),('female','male')) AS X(OldGender,NewGender) WHERE SimpleTable.Gender=X.OldGender As per author this is a slow solution but I love how syntaxes are placed and used here. I love how he used syntax here. I will say this is the most beautifully written solution (not necessarily it is best). Bonus: Solution by Madhivanan Somehow I was confident Madhi – SQL Server MVP will come up with something which I will be compelled to read. He has written a complete blog post on this subject and I encourage all of you to go ahead and read it. Now personally I wanted to list every single comment here. There are some so good that I am just amazed with the creativity. I will write a part of this blog post in future. However, here is the challenge for you. Challenge: Go over 50+ various solutions listed to the simple problem here. Here are my two asks for you. 1) Pick your best solution and list here in the comment. This exercise will for sure teach us one or two things. 2) Write your own solution which is yet not covered already listed 50 solutions. I am confident that there is no end to creativity. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Function, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• SQL SERVER – Fix: Error : 402 The data types ntext and varchar are incompatible in the equal to operator

  - by pinaldave

  Some errors are very simple to understand but the solution of the same is not easy to figure out. Here is one of the similar errors where it clearly suggests where the problem is but does not tell what is the solution. Additionally, there are multiple solutions so developers often get confused with which one is correct and which one is not correct. Let us first recreate scenario and understand where the problem is. Let us run following USE Tempdb GO CREATE TABLE TestTable (ID INT, MyText NTEXT) GO SELECT ID, MyText FROM TestTable WHERE MyText = 'AnyText' GO DROP TABLE TestTable GO When you run above script it will give you following error. Msg 402, Level 16, State 1, Line 1 The data types ntext and varchar are incompatible in the equal to operator. One of the questions I often receive is that voucher is for sure compatible to equal to operator, then why does this error show up. Well, the answer is much simpler I think we have not understood the error message properly. Please see the image below. The next and varchar are not compatible when compared with each other using equal sign. Now let us change the data type on the right side of the string to nvarchar from varchar. To do that we will put N’ before the string. USE Tempdb GO CREATE TABLE TestTable (ID INT, MyText NTEXT) GO SELECT ID, MyText FROM TestTable WHERE MyText = N'AnyText' GO DROP TABLE TestTable GO When you run above script it will give following error. Msg 402, Level 16, State 1, Line 1 The data types ntext and nvarchar are incompatible in the equal to operator. You can see that error message also suggests that now we are comparing next to nvarchar. Now as we have understood the error properly, let us see various solutions to the above problem. Solution 1: Convert the data types to match with each other using CONVERT function. Change the datatype of the MyText to nvarchar. SELECT ID, MyText FROM TestTable WHERE CONVERT(NVARCHAR(MAX), MyText) = N'AnyText' GO Solution 2: Convert the data type of columns from NTEXT to NVARCHAR(MAX) (TEXT to VARCHAR(MAX) ALTER TABLE TestTable ALTER COLUMN MyText NVARCHAR(MAX) GO Now you can run the original query again and it will work fine. Solution 3: Using LIKE command instead of Equal to command. SELECT ID, MyText FROM TestTable WHERE MyText LIKE 'AnyText' GO Well, any of the three of the solutions will work. Here is my suggestion if you can change the column data type from ntext or text to nvarchar or varchar, you should follow that path as text and ntext datatypes are marked as deprecated. All developers any way to change the deprecated data types in future, it will be a good idea to change them right early. If due to any reason you can not convert the original column use Solution 1 for temporary fix. Solution 3 is the not the best solution and use it as a last option. Did I miss any other method? If yes, please let me know and I will add the solution to original blog post with due credit. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Error Messages, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• MvcExtensions - PerRequestTask

  - by kazimanzurrashid

  In the previous post, we have seen the BootstrapperTask which executes when the application starts and ends, similarly there are times when we need to execute some custom logic when a request starts and ends. Usually, for this kind of scenario we create HttpModule and hook the begin and end request events. There is nothing wrong with this approach, except HttpModules are not at all IoC containers friendly, also defining the HttpModule execution order is bit cumbersome, you either have to modify the machine.config or clear the HttpModules and add it again in web.config. Instead, you can use the PerRequestTask which is very much container friendly as well as supports execution orders. Lets few examples where it can be used. Remove www Subdomain Lets say we want to remove the www subdomain, so that if anybody types http://www.mydomain.com it will automatically redirects to http://mydomain.com. public class RemoveWwwSubdomain : PerRequestTask { public RemoveWww() { Order = DefaultOrder - 1; } protected override TaskContinuation ExecuteCore(PerRequestExecutionContext executionContext) { const string Prefix = "http://www."; Check.Argument.IsNotNull(executionContext, "executionContext"); HttpContextBase httpContext = executionContext.HttpContext; string url = httpContext.Request.Url.ToString(); bool startsWith3W = url.StartsWith(Prefix, StringComparison.OrdinalIgnoreCase); bool shouldContinue = true; if (startsWith3W) { string newUrl = "http://" + url.Substring(Prefix.Length); HttpResponseBase response = httpContext.Response; response.StatusCode = (int)HttpStatusCode.MovedPermanently; response.Status = "301 Moved Permanently"; response.RedirectLocation = newUrl; response.SuppressContent = true; shouldContinue = false; } return shouldContinue ? TaskContinuation.Continue : TaskContinuation.Break; } } As you can see, first, we are setting the order so that we do not have to execute the remaining tasks of the chain when we are redirecting, next in the ExecuteCore, we checking the whether www is present, if present we are sending a permanently moved http status code and breaking the task execution chain otherwise we are continuing with the chain. Blocking IP Address Lets take another scenario, your application is hosted in a shared hosting environment where you do not have the permission to change the IIS setting and you want to block certain IP addresses from visiting your application. Lets say, you maintain a list of IP address in database/xml files which you want to block, you have a IBannedIPAddressRepository service which is used to match banned IP Address. public class BlockRestrictedIPAddress : PerRequestTask { protected override TaskContinuation ExecuteCore(PerRequestExecutionContext executionContext) { bool shouldContinue = true; HttpContextBase httpContext = executionContext.HttpContext; if (!httpContext.Request.IsLocal) { string ipAddress = httpContext.Request.UserHostAddress; HttpResponseBase httpResponse = httpContext.Response; if (executionContext.ServiceLocator.GetInstance<IBannedIPAddressRepository>().IsMatching(ipAddress)) { httpResponse.StatusCode = (int)HttpStatusCode.Forbidden; httpResponse.StatusDescription = "IPAddress blocked."; shouldContinue = false; } } return shouldContinue ? TaskContinuation.Continue : TaskContinuation.Break; } } Managing Database Session Now, let see how it can be used to manage NHibernate session, assuming that ISessionFactory of NHibernate is already registered in our container. public class ManageNHibernateSession : PerRequestTask { private ISession session; protected override TaskContinuation ExecuteCore(PerRequestExecutionContext executionContext) { ISessionFactory factory = executionContext.ServiceLocator.GetInstance<ISessionFactory>(); session = factory.OpenSession(); return TaskContinuation.Continue; } protected override void DisposeCore() { session.Close(); session.Dispose(); } } As you can see PerRequestTask can be used to execute small and precise tasks in the begin/end request, certainly if you want to execute other than begin/end request there is no other alternate of HttpModule. That’s it for today, in the next post, we will discuss about the Action Filters, so stay tuned.

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• Speed up SQL Server queries with PREFETCH

  - by Akshay Deep Lamba

  Problem The SAN data volume has a throughput capacity of 400MB/sec; however my query is still running slow and it is waiting on I/O (PAGEIOLATCH_SH). Windows Performance Monitor shows data volume speed of 4MB/sec. Where is the problem and how can I find the problem? Solution This is another summary of a great article published by R. Meyyappan at www.sqlworkshops.com.  In my opinion, this is the first article that highlights and explains with working examples how PREFETCH determines the performance of a Nested Loop join.  First of all, I just want to recall that Prefetch is a mechanism with which SQL Server can fire up many I/O requests in parallel for a Nested Loop join. When SQL Server executes a Nested Loop join, it may or may not enable Prefetch accordingly to the number of rows in the outer table. If the number of rows in the outer table is greater than 25 then SQL will enable and use Prefetch to speed up query performance, but it will not if it is less than 25 rows. In this section we are going to see different scenarios where prefetch is automatically enabled or disabled. These examples only use two tables RegionalOrder and Orders.  If you want to create the sample tables and sample data, please visit this site www.sqlworkshops.com. The breakdown of the data in the RegionalOrders table is shown below and the Orders table contains about 6 million rows. In this first example, I am creating a stored procedure against two tables and then execute the stored procedure.  Before running the stored proceudre, I am going to include the actual execution plan. --Example provided by www.sqlworkshops.com --Create procedure that pulls orders based on City --Do not forget to include the actual execution plan CREATE PROC RegionalOrdersProc @City CHAR(20) AS BEGIN DECLARE @OrderID INT, @OrderDetails CHAR(200) SELECT @OrderID = o.OrderID, @OrderDetails = o.OrderDetails       FROM RegionalOrders ao INNER JOIN Orders o ON (o.OrderID = ao.OrderID)       WHERE City = @City END GO SET STATISTICS time ON GO --Example provided by www.sqlworkshops.com --Execute the procedure with parameter SmallCity1 EXEC RegionalOrdersProc 'SmallCity1' GO After running the stored procedure, if we right click on the Clustered Index Scan and click Properties we can see the Estimated Numbers of Rows is 24.    If we right click on Nested Loops and click Properties we do not see Prefetch, because it is disabled. This behavior was expected, because the number of rows containing the value ‘SmallCity1’ in the outer table is less than 25.   Now, if I run the same procedure with parameter ‘BigCity’ will Prefetch be enabled? --Example provided by www.sqlworkshops.com --Execute the procedure with parameter BigCity --We are using cached plan EXEC RegionalOrdersProc 'BigCity' GO As we can see from the below screenshot, prefetch is not enabled and the query takes around 7 seconds to execute. This is because the query used the cached plan from ‘SmallCity1’ that had prefetch disabled. Please note that even if we have 999 rows for ‘BigCity’ the Estimated Numbers of Rows is still 24.   Finally, let’s clear the procedure cache to trigger a new optimization and execute the procedure again. DBCC freeproccache GO EXEC RegionalOrdersProc 'BigCity' GO This time, our procedure runs under a second, Prefetch is enabled and the Estimated Number of Rows is 999.   The RegionalOrdersProc can be optimized by using the below example where we are using an optimizer hint. I have also shown some other hints that could be used as well. --Example provided by www.sqlworkshops.com --You can fix the issue by using any of the following --hints --Create procedure that pulls orders based on City DROP PROC RegionalOrdersProc GO CREATE PROC RegionalOrdersProc @City CHAR(20) AS BEGIN DECLARE @OrderID INT, @OrderDetails CHAR(200) SELECT @OrderID = o.OrderID, @OrderDetails = o.OrderDetails       FROM RegionalOrders ao INNER JOIN Orders o ON (o.OrderID = ao.OrderID)       WHERE City = @City       --Hinting optimizer to use SmallCity2 for estimation       OPTION (optimize FOR (@City = 'SmallCity2'))       --Hinting optimizer to estimate for the currnet parameters       --option (recompile)       --Hinting optimize not to use histogram rather       --density for estimation (average of all 3 cities)       --option (optimize for (@City UNKNOWN))       --option (optimize for UNKNOWN) END GO Conclusion, this tip was mainly aimed at illustrating how Prefetch can speed up query execution and how the different number of rows can trigger this.

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• Thinktecture.IdentityModel: Comparing Strings without leaking Timinig Information

  - by Your DisplayName here!

  Paul Hill commented on a recent post where I was comparing HMACSHA256 signatures. In a nutshell his complaint was that I am leaking timing information while doing so – or in other words, my code returned faster with wrong (or partially wrong) signatures than with the correct signature. This can be potentially used for timing attacks like this one. I think he got a point here, especially in the era of cloud computing where you can potentially run attack code on the same physical machine as your target to do high resolution timing analysis (see here for an example). It turns out that it is not that easy to write a time-constant string comparer due to all sort of (unexpected) clever optimization mechanisms in the CLR. With the help and feedback of Paul and Shawn I came up with this: Structure the code in a way that the CLR will not try to optimize it In addition turn off optimization (just in case a future version will come up with new optimization methods) Add a random sleep when the comparison fails (using Shawn’s and Stephen’s nice Random wrapper for RNGCryptoServiceProvider). You can find the full code in the Thinktecture.IdentityModel download. [MethodImpl(MethodImplOptions.NoOptimization)] public static bool IsEqual(string s1, string s2) {     if (s1 == null && s2 == null)     {         return true;     }       if (s1 == null || s2 == null)     {         return false;     }       if (s1.Length != s2.Length)     {         return false;     }       var s1chars = s1.ToCharArray();     var s2chars = s2.ToCharArray();       int hits = 0;     for (int i = 0; i < s1.Length; i++)     {         if (s1chars[i].Equals(s2chars[i]))         {             hits += 2;         }         else         {             hits += 1;         }     }       bool same = (hits == s1.Length * 2);       if (!same)     {         var rnd = new CryptoRandom();         Thread.Sleep(rnd.Next(0, 10));     }       return same; }

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• Detecting Process Shutdown/Startup Events through ActivationAgents

  - by Ramkumar Menon

  @10g - This post is motivated by one of my close friends and colleague - who wanted to proactively know when a BPEL process shuts down/re-activates. This typically happens when you have a BPEL Process that has an inbound polling adapter, when the adapter loses connectivity to the source system. Or whatever causes it. One valuable suggestion came in from one of my colleagues - he suggested I write my own ActivationAgent to do the job. Well, it really worked. Here is a sample ActivationAgent that you can use. There are few methods you need to override from BaseActivationAgent, and you are on your way to receiving notifications/what not, whenever the shutdown/startup events occur. In the example below, I am retrieving the emailAddress property [that is specified in your bpel.xml activationAgent section] and use that to send out an email notification on the activation agent initialization. You could choose to do different things. But bottomline is that you can use the below-mentioned API to access the very same properties that you specify in the bpel.xml. package com.adapter.custom.activation; import com.collaxa.cube.activation.BaseActivationAgent; import com.collaxa.cube.engine.ICubeContext; import com.oracle.bpel.client.BPELProcessId; import java.util.Date; import java.util.Properties; public class LifecycleManagerActivationAgent extends BaseActivationAgent { public BPELProcessId getBPELProcessId() { return super.getBPELProcessId(); } private void handleInit() throws Exception { //Write initialization code here System.err.println("Entered initialization code...."); //e.g. String emailAddress = getActivationAgentDescriptor().getPropertyValue(emailAddress); //send an email sendEmail(emailAddress); } private void handleLoad() throws Exception { //Write load code here System.err.println("Entered load code...."); } private void handleUnload() throws Exception { //Write unload code here System.err.println("Entered unload code...."); } private void handleUninit() throws Exception { //Write uninitialization code here System.err.println("Entered uninitialization code...."); } public void init(ICubeContext icubecontext) throws Exception { super.init(icubecontext); System.err.println("Initializing LifecycleManager Activation Agent ....."); handleInit(); } public void unload(ICubeContext icubecontext) throws Exception { super.unload(icubecontext); System.err.println("Unloading LifecycleManager Activation Agent ....."); handleUnload(); } public void uninit(ICubeContext icubecontext) throws Exception{ super.uninit(icubecontext); System.err.println("Uninitializing LifecycleManager Activation Agent ....."); handleUninit(); } public String getName() { return "Lifecyclemanageractivationagent"; } public void onStateChanged(int i, ICubeContext iCubeContext) { } public void onLifeCycleChanged(int i, ICubeContext iCubeContext) { } public void onUndeployed(ICubeContext iCubeContext) { } public void onServerShutdown() { } } Once you compile this code, generate a jar file and ensure you add it to the server startup classpath. The library is ready for use after the server restarts. To use this activationAgent, add an additional activationAgent entry in the bpel.xml for the BPEL Process that you wish to monitor. After you deploy the process, the ActivationAgent object will be called back whenever the events mentioned in the overridden methods are raised. [init(), load(), unload(), uninit()]. Subsequently, your custom code is executed. Sample bpel.xml illustrating activationAgent definition and property definition. <?xml version="1.0" encoding="UTF-8"? <BPELSuitcase timestamp="1291943469921" revision="1.0" <BPELProcess wsdlPort="{http://xmlns.oracle.com/BPELTest}BPELTestPort" src="BPELTest.bpel" wsdlService="{http://xmlns.oracle.com/BPELTest}BPELTest" id="BPELTest" <partnerLinkBindings <partnerLinkBinding name="client" <property name="wsdlLocation"BPELTest.wsdl</property </partnerLinkBinding <partnerLinkBinding name="test" <property name="wsdlLocation"test.wsdl</property </partnerLinkBinding </partnerLinkBindings <activationAgents <activationAgent className="oracle.tip.adapter.fw.agent.jca.JCAActivationAgent" partnerLink="test" <property name="portType"Read_ptt</property </activationAgent <activationAgent className="com.oracle.bpel.activation.LifecycleManagerActivationAgent" partnerLink="test" <property name="emailAddress"[email protected]</property </activationAgent </activationAgents </BPELProcess </BPELSuitcase em

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• In GLSL is it possible to offset vertices based on height map colour?

  - by Rob

  I am attempting to generate some terrain based upon a heightmap. I have generated a 32 x 32 grid and a corresponding height map - In my vertex shader I am trying to offset the position of the Y axis based upon the colour of the heightmap, white vertices being higher than black ones. //Vertex Shader Code #version 330 uniform mat4 modelMatrix; uniform mat4 viewMatrix; uniform mat4 projectionMatrix; uniform sampler2D heightmap; layout (location=0) in vec4 vertexPos; layout (location=1) in vec4 vertexColour; layout (location=3) in vec2 vertexTextureCoord; layout (location=4) in float offset; out vec4 fragCol; out vec4 fragPos; out vec2 fragTex; void main() { // Retreive the current pixel's colour vec4 hmColour = texture(heightmap,vertexTextureCoord); // Offset the y position by the value of current texel's colour value ? vec4 offset = vec4(vertexPos.x , vertexPos.y + hmColour.r, vertexPos.z , 1.0); // Final Position gl_Position = projectionMatrix * viewMatrix * modelMatrix * offset; // Data sent to Fragment Shader. fragCol = vertexColour; fragPos = vertexPos; fragTex = vertexTextureCoord; } However the code I have produced only creates a grid with none of the y vertices higher than any others. This is the C++ code that generates the grid and texture co-orientates which I believe to be correct as the texture is mapped to the grid, hence the white blob in the middle. The grid-lines are generated in the fragment shader, sorry for any confusion. I have tried multiplying the r value of hmColour by 1000 unfortunately that had no effect. The only other problem it could be is that the texture coordinate data is incorrect ? for (int z = 0; z < MAP_Z ; z++) { for(int x = 0; x < MAP_X ; x++) { //Generate Vertex Buffer vertexData[iVertex++] = float (x) * MAP_X; vertexData[iVertex++] = 0; vertexData[iVertex++] = -(float) (z) * MAP_Z; //Colour Buffer NOT NEEDED colourData[iColour++] = 255.0f; // R colourData[iColour++] = 1.0f; // G colourData[iColour++] = 0.0f; // B //Texture Buffer textureData[iTexture++] = (float ) x * (1.0f / MAP_X); textureData[iTexture++] = (float ) z * (1.0f / MAP_Z); } } The heightmap texture I am trying to use appears like so (without grid-lines). This is the corresponding fragment shader // Fragment Shader Code #version 330 uniform sampler2D hmTexture; layout (location=0) out vec4 fragColour; in vec2 fragTex; in vec4 pos; void main(void) { vec2 line = fragTex * 32; // Without Gridlines fragColour = texture(hmTexture,fragTex); // With grid lines // + mix(vec4(0.0, 0.0, 1.0, 0.0), vec4(1.0, 1.0, 1.0, 1.0), // smoothstep(0.05,fract(line.y), 0.99) * smoothstep(0.05,fract(line.x),0.99)); }

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• Gnome Shell Theme Problem on Ubuntu 11.10

  - by Khurram Majeed

  I am trying to install ANewStart GNOME shell themes on Ubuntu 11.10. I have installed gnome shell extension for themes: sudo add-apt-repository ppa:webupd8team/gnome3 sudo apt-get update sudo apt-get install gnome-shell-extensions-user-theme I got the instructions from here ANewStart GNOME Shell Theme + AwOken Icons Theme = Pure Art. But when I go to "Advanced Settings - Shell Extensions" its empty... There is nothing. Also there is a orange triangle sign next to Shell Theme drop down in Advanced Settings - Theme. When I try to run the gnome-tweak-tool from terminal I get following error: imresh@imresh-laptop:~$ gnome-tweak-tool CRITICAL: Error parsing schema org.gnome.shell (/usr/share/glib-2.0/schemas/org.gnome.shell.gschema.xml) Traceback (most recent call last): File "/usr/lib/python2.7/dist-packages/gtweak/gsettings.py", line 45, in __init__ summary = key.getElementsByTagName("summary")[0].childNodes[0].data IndexError: list index out of range WARNING : Error detecting shell Traceback (most recent call last): File "/usr/lib/python2.7/dist-packages/gtweak/tweaks/tweak_shell_extensions.py", line 145, in __init__ shell = GnomeShellFactory().get_shell() File "/usr/lib/python2.7/dist-packages/gtweak/utils.py", line 38, in getinstance instances[cls] = cls() File "/usr/lib/python2.7/dist-packages/gtweak/gshellwrapper.py", line 123, in __init__ v = map(int,proxy.version.split(".")) File "/usr/lib/python2.7/dist-packages/gtweak/gshellwrapper.py", line 46, in version return json.loads(self.execute_js('const Config = imports.misc.config; Config.PACKAGE_VERSION')) File "/usr/lib/python2.7/dist-packages/gtweak/gshellwrapper.py", line 39, in execute_js result, output = self.proxy.Eval('(s)', js) File "/usr/lib/python2.7/dist-packages/gi/overrides/Gio.py", line 148, in __call__ kwargs.get('flags', 0), kwargs.get('timeout', -1), None) File "/usr/lib/python2.7/dist-packages/gi/types.py", line 43, in function return info.invoke(*args, **kwargs) GError: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.Shell was not provided by any .service files WARNING : Shell not running Traceback (most recent call last): File "/usr/lib/python2.7/dist-packages/gtweak/tweaks/tweak_shell.py", line 57, in __init__ self._shell = GnomeShellFactory().get_shell() File "/usr/lib/python2.7/dist-packages/gtweak/utils.py", line 38, in getinstance instances[cls] = cls() File "/usr/lib/python2.7/dist-packages/gtweak/gshellwrapper.py", line 123, in __init__ v = map(int,proxy.version.split(".")) File "/usr/lib/python2.7/dist-packages/gtweak/gshellwrapper.py", line 46, in version return json.loads(self.execute_js('const Config = imports.misc.config; Config.PACKAGE_VERSION')) File "/usr/lib/python2.7/dist-packages/gtweak/gshellwrapper.py", line 39, in execute_js result, output = self.proxy.Eval('(s)', js) File "/usr/lib/python2.7/dist-packages/gi/overrides/Gio.py", line 148, in __call__ kwargs.get('flags', 0), kwargs.get('timeout', -1), None) File "/usr/lib/python2.7/dist-packages/gi/types.py", line 43, in function return info.invoke(*args, **kwargs) GError: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.Shell was not provided by any .service files WARNING : Could not list shell extensions Traceback (most recent call last): File "/usr/lib/python2.7/dist-packages/gtweak/tweaks/tweak_shell.py", line 62, in __init__ extensions = self._shell.list_extensions() AttributeError: ShellThemeTweak instance has no attribute '_shell' (gnome-tweak-tool:5323): Gtk-CRITICAL **: gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed (gnome-tweak-tool:5323): Gtk-CRITICAL **: gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed (gnome-tweak-tool:5323): Gtk-CRITICAL **: gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed (gnome-tweak-tool:5323): Gtk-CRITICAL **: gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed (gnome-tweak-tool:5323): Gtk-CRITICAL **: gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed (gnome-tweak-tool:5323): Gtk-CRITICAL **: gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed (gnome-tweak-tool:5323): Gtk-CRITICAL **: gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed (gnome-tweak-tool:5323): Gtk-CRITICAL **: gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed (gnome-tweak-tool:5323): Gtk-CRITICAL **: gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed (gnome-tweak-tool:5323): Gtk-CRITICAL **: gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed (gnome-tweak-tool:5323): Gtk-CRITICAL **: gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed (gnome-tweak-tool:5323): Gtk-CRITICAL **: gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed (gnome-tweak-tool:5323): Gtk-CRITICAL **: gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed (gnome-tweak-tool:5323): Gtk-CRITICAL **: gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed (gnome-tweak-tool:5323): Gtk-CRITICAL **: gtk_widget_get_preferred_height_for_width: assertion `width >= 0' failed Please help me in fixing this. I have also restarted the computer many times it does not make a difference.

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• OpenGL slower than Canvas

  - by VanDir

  Up to 3 days ago I used a Canvas in a SurfaceView to do all the graphics operations but now I switched to OpenGL because my game went from 60FPS to 30/45 with the increase of the sprites in some levels. However, I find myself disappointed because OpenGL now reaches around 40/50 FPS at all levels. Surely (I hope) I'm doing something wrong. How can I increase the performance at stable 60FPS? My game is pretty simple and I can not believe that it is impossible to reach them. I use 2D sprite texture applied to a square for all the objects. I use a transparent GLSurfaceView, the real background is applied in a ImageView behind the GLSurfaceView. Some code public MyGLSurfaceView(Context context, AttributeSet attrs) { super(context); setZOrderOnTop(true); setEGLConfigChooser(8, 8, 8, 8, 0, 0); getHolder().setFormat(PixelFormat.RGBA_8888); mRenderer = new ClearRenderer(getContext()); setRenderer(mRenderer); setLongClickable(true); setFocusable(true); } public void onSurfaceCreated(final GL10 gl, EGLConfig config) { gl.glEnable(GL10.GL_TEXTURE_2D); gl.glShadeModel(GL10.GL_SMOOTH); gl.glDisable(GL10.GL_DEPTH_TEST); gl.glDepthMask(false); gl.glEnable(GL10.GL_ALPHA_TEST); gl.glAlphaFunc(GL10.GL_GREATER, 0); gl.glEnable(GL10.GL_BLEND); gl.glBlendFunc(GL10.GL_ONE, GL10.GL_ONE_MINUS_SRC_ALPHA); gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST); } public void onSurfaceChanged(GL10 gl, int width, int height) { gl.glViewport(0, 0, width, height); gl.glMatrixMode(GL10.GL_PROJECTION); gl.glLoadIdentity(); gl.glOrthof(0, width, height, 0, -1f, 1f); gl.glMatrixMode(GL10.GL_MODELVIEW); gl.glLoadIdentity(); } public void onDrawFrame(GL10 gl) { gl.glClear(GL10.GL_COLOR_BUFFER_BIT); gl.glMatrixMode(GL10.GL_MODELVIEW); gl.glLoadIdentity(); gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY); // Draw all the graphic object. for (byte i = 0; i < mGame.numberOfObjects(); i++){ mGame.getObject(i).draw(gl); } // Disable the client state before leaving gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY); } mGame.getObject(i).draw(gl) is for all the objects like this: /* HERE there is always a translatef and scalef transformation and sometimes rotatef */ gl.glBindTexture(GL10.GL_TEXTURE_2D, mTexPointer[0]); // Point to our vertex buffer gl.glVertexPointer(3, GL10.GL_FLOAT, 0, mVertexBuffer); gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, mTextureBuffer); // Draw the vertices as triangle strip gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, mVertices.length / 3); EDIT: After some test it seems to be due to the transparent GLSurfaceView. If I delete this line of code: setEGLConfigChooser(8, 8, 8, 8, 0, 0); the background becomes all black but I reach 60 fps. What can I do?

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• A quick look at: sys.dm_os_buffer_descriptors

  - by Jonathan Allen

  SQL Server places data into cache as it reads it from disk so as to speed up future queries. This dmv lets you see how much data is cached at any given time and knowing how this changes over time can help you ensure your servers run smoothly and are adequately resourced to run your systems. This dmv gives the number of cached pages in the buffer pool along with the database id that they relate to: USE [tempdb] GO SELECT COUNT(*) AS cached_pages_count , CASE database_id WHEN 32767 THEN 'ResourceDb' ELSE DB_NAME(database_id) END AS Database_name FROM sys.dm_os_buffer_descriptors GROUP BY DB_NAME(database_id) , database_id ORDER BY cached_pages_count DESC; This gives you results which are quite useful, but if you add a new column with the code: …to convert the pages value to show a MB value then they become more relevant and meaningful. To see how your server reacts to queries, start up SSMS and connect to a test server and database – mine is called AdventureWorks2008. Make sure you start from a know position by running: -- Only run this on a test server otherwise your production server's-- performance may drop off a cliff and your phone will start ringing. DBCC DROPCLEANBUFFERS GO Now we can run a query that would normally turn a DBA’s hair white: USE [AdventureWorks2008] go SELECT * FROM [Sales].[SalesOrderDetail] AS sod INNER JOIN [Sales].[SalesOrderHeader] AS soh ON [sod].[SalesOrderID] = [soh].[SalesOrderID] …and then check our cache situation: A nice low figure – not! Almost 2000 pages of data in cache equating to approximately 15MB. Luckily these tables are quite narrow; if this had been on a table with more columns then this could be even more dramatic. So, let’s make our query more efficient. After resetting the cache with the DROPCLEANBUFFERS and FREEPROCCACHE code above, we’ll only select the columns we want and implement a WHERE predicate to limit the rows to a specific customer. SELECT [sod].[OrderQty] , [sod].[ProductID] , [soh].[OrderDate] , [soh].[CustomerID] FROM [Sales].[SalesOrderDetail] AS sod INNER JOIN [Sales].[SalesOrderHeader] AS soh ON [sod].[SalesOrderID] = [soh].[SalesOrderID] WHERE [soh].[CustomerID] = 29722 …and check our effect cache: Now that is more sympathetic to our server and the other systems sharing its resources. I can hear you asking: “What has this got to do with logging, Jonathan?” Well, a smart DBA will keep an eye on this metric on their servers so they know how their hardware is coping and be ready to investigate anomalies so that no ‘disruptive’ code starts to unsettle things. Capturing this information over a period of time can lead you to build a picture of how a database relies on the cache and how it interacts with other databases. This might allow you to decide on appropriate schedules for over night jobs or otherwise balance the work of your server. You could schedule this job to run with a SQL Agent job and store the data in your DBA’s database by creating a table with: IF OBJECT_ID('CachedPages') IS NOT NULL DROP TABLE CachedPages CREATE TABLE CachedPages ( cached_pages_count INT , MB INT , Database_Name VARCHAR(256) , CollectedOn DATETIME DEFAULT GETDATE() ) …and then filling it with: INSERT INTO [dbo].[CachedPages] ( [cached_pages_count] , [MB] , [Database_Name] ) SELECT COUNT(*) AS cached_pages_count , ( COUNT(*) * 8.0 ) / 1024 AS MB , CASE database_id WHEN 32767 THEN 'ResourceDb' ELSE DB_NAME(database_id) END AS Database_name FROM sys.dm_os_buffer_descriptors GROUP BY database_id After this has been left logging your system metrics for a while you can easily see how your databases use the cache over time and may see some spikes that warrant your attention. This sort of logging can be applied to all sorts of server statistics so that you can gather information that will give you baseline data on how your servers are performing. This means that when you get a problem you can see what statistics are out of their normal range and target you efforts to resolve the issue more rapidly.

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• OpenGL/GLSL: Render to cube map?

  - by BobDole

  I'm trying to figure out how to render my scene to a cube map. I've been stuck on this for a bit and figured I would ask you guys for some help. I'm new to OpenGL and this is the first time I'm using a FBO. I currently have a working example of using a cubemap bmp file, and the samplerCube sample type in the fragment shader is attached to GL_TEXTURE1. I'm not changing the shader code at all. I'm just changing the fact that I wont be calling the function that was loading the cubemap bmp file and trying to use the below code to render to a cubemap. You can see below that I'm also attaching the texture again to GL_TEXTURE1. This is so when I set the uniform: glUniform1i(getUniLoc(myProg, "Cubemap"), 1); it can access it in my fragment shader via uniform samplerCube Cubemap. I'm calling the below function like so: cubeMapTexture = renderToCubeMap(150, GL_RGBA8, GL_RGBA, GL_UNSIGNED_BYTE); Now, I realize in the draw loop below that I'm not changing the view direction to look down the +x, -x, +y, -y, +z, -z axis. I really was just wanting to see something working first before implemented that. I figured I should at least see something on my object the way the code is now. I'm not seeing anything, just straight black. I've made my background white still the object is black. I've removed lighting, and coloring to just sample the cubemap texture and still black. I'm thinking the problem might be the format types when setting my texture which is GL_RGB8, GL_RGBA but I've also tried: GL_RGBA, GL_RGBA GL_RGB, GL_RGB I thought this would be standard since we are rendering to a texture attached to a framebuffer, but I've seen different examples that use different enum values. I've also tried binding the cube map texture in every draw call that I'm wanting to use the cube map: glBindTexture(GL_TEXTURE_CUBE_MAP, cubeMapTexture); Also, I'm not creating a depth buffer for the FBO which I saw in most examples, because I'm only wanting the color buffer for my cube map. I actually added one to see if that was the problem and still got the same results. I could of fudged that up when I tried. Any help that can point me in the right direction would be appreciated. GLuint renderToCubeMap(int size, GLenum InternalFormat, GLenum Format, GLenum Type) { // color cube map GLuint textureObject; int face; GLenum status; //glEnable(GL_TEXTURE_2D); glActiveTexture(GL_TEXTURE1); glGenTextures(1, &textureObject); glBindTexture(GL_TEXTURE_CUBE_MAP, textureObject); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE); for (face = 0; face < 6; face++) { glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + face, 0, InternalFormat, size, size, 0, Format, Type, NULL); } // framebuffer object glGenFramebuffers(1, &fbo); glBindFramebuffer(GL_FRAMEBUFFER, fbo); glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X, textureObject, 0); status = glCheckFramebufferStatus(GL_FRAMEBUFFER); printf("%d\"\n", status); printf("%d\n", GL_FRAMEBUFFER_COMPLETE); glViewport(0,0,size, size); for (face = 1; face < 6; face++) { drawSpheres(); glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,GL_TEXTURE_CUBE_MAP_POSITIVE_X + face, textureObject, 0); } //Bind 0, which means render to back buffer, as a result, fb is unbound glBindFramebuffer(GL_FRAMEBUFFER, 0); return textureObject; }

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• Visual Studio Exceptions dialogs

  - by Daniel Moth

  Previously I covered step 1 of live debugging with start and attach. Once the debugger is attached, you want to go to step 2 of live debugging, which is to break. One way to break under the debugger is to do nothing, and just wait for an exception to occur in your code. This is true for all types of code that you debug in Visual Studio, and let's consider the following piece of C# code:3: static void Main() 4: { 5: try 6: { 7: int i = 0; 8: int r = 5 / i; 9: } 10: catch (System.DivideByZeroException) {/*gulp. sue me.*/} 11: System.Console.ReadLine(); 12: } If you run this under the debugger do you expect an exception on line 8? It is a trick question: you have to know whether I have configured the debugger to break when exceptions are thrown (first-chance exceptions) or only when they are unhandled. The place you do that is in the Exceptions dialog which is accessible from the Debug->Exceptions menu and on my installation looks like this: Note that I have checked all CLR exceptions. I could have expanded (like shown for the C++ case in my screenshot) and selected specific exceptions. To read more about this dialog, please read the corresponding Exception Handling debugging msdn topic and all its subtopics. So, for the code above, the debugger will break execution due to the thrown exception (exactly as if the try..catch was not there), so I see the following Exception Thrown dialog: Note the following: I can hit continue (or hit break and then later continue) and the program will continue fine since I have a catch handler. If this was an unhandled exception, then that is what the dialog would say (instead of first chance exception) and continuing would crash the app. That hyperlinked text ("Open Exception Settings") opens the Exceptions dialog I described further up. The coolest thing to note is the checkbox - this is new in this latest release of Visual Studio: it is a shortcut to the checkbox in the Exceptions dialog, so you don't have to open it to change this setting for this specific exception - you can toggle that option right from this dialog. Finally, if you try the code above on your system, you may observe a couple of differences from my screenshots. The first is that you may have an additional column of checkboxes in the Exceptions dialog. The second is that the last dialog I shared may look different to you. It all depends on the Debug->Options settings, and the two relevant settings are in this screenshot: The Exception assistant is what configures the look of the UI when the debugger wants to indicate exception to you, and the Just My Code setting controls the extra column in the Exception dialog. You can read more about those options on MSDN: How to break on User-Unhandled exceptions (plus Gregg’s post) and Exception Assistant. Before I leave you to go play with this stuff a bit more, please note that this level of debugging is now available for JavaScript too, and if you are looking at the Exceptions dialog and wondering what the "GPU Memory Access Exceptions" node is about, stay tuned on the C++ AMP blog ;-) Comments about this post by Daniel Moth welcome at the original blog.

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• Thread safe double buffering

  - by kdavis8

  I am trying to implement a draw map method that will draw the tiled image across the surface of the component. I'm having issue with this code. The double buffering does not seem to be working, because the sprite flickers like crazy; my source code: package myPackage; import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.awt.Toolkit; import java.awt.image.BufferStrategy; import java.awt.image.BufferedImage; import javax.swing.JFrame; public class GameView extends JFrame implements Runnable { public BufferedImage backbuffer; public Graphics2D g2d; public Image img; Thread gameloop; Scene scene; public GameView() { super("Game View"); setSize(600, 600); setVisible(true); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); backbuffer = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_RGB); g2d = backbuffer.createGraphics(); Toolkit tk = Toolkit.getDefaultToolkit(); img = tk.getImage(this.getClass().getResource("cage.png")); scene = new Scene(g2d, this); gameloop = new Thread(this); gameloop.start(); } public static void main(String args[]) { new GameView(); } public void paint(Graphics g) { g.drawImage(backbuffer, 0, 0, this); repaint(); } @Override public void run() { // TODO Auto-generated method stub Thread t = Thread.currentThread(); while (t == gameloop) { scene.getScene("dirtmap"); g2d.drawImage(img, 80, 80,this![enter image description here][1]); } } private void drawScene(String string) { // TODO Auto-generated method stub // g2d.setColor(Color.white); // g2d.fillRect(0, 0, getWidth(), getHeight()); scene.getScene(string); } } package myPackage; import java.awt.Color; import java.awt.Component; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.awt.Toolkit; public class Scene { Graphics g2d; Component c; boolean loaded = false; public Scene(Graphics2D gr, Component co) { g2d = gr; c = co; } public void getScene(String mapName) { Toolkit tk = Toolkit.getDefaultToolkit(); Image tile = tk.getImage(this.getClass().getResource("dirt.png")); // g2d.setColor(Color.red); for (int y = 0; y <= 18; y++) { for (int x = 0; x <= 18; x += 1) { g2d.drawImage(tile, x * 32, y * 32, c); } } loaded = true; } }

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• Override ToString() in your Classes

  - by psheriff

  One of the reasons I love teaching is because of the questions that I get from attendees. I was giving a presentation at DevConnections and was showing a collection of Product objects. When I hovered over the variable that contained the collection, it looked like Figure 2. As you can see in the collection, I have actual product names of my videos from www.pdsa.com/videos being displayed. To get your data to appear in the data tips you must override the ToString() method in your class. To illustrate this, take the following simple Product class shown below: public class Product{  public string ProductName { get; set; }  public int ProductId { get; set; }} This class does not have an override of the ToString() method so if you create a collection of Product objects you will end up with data tips that look like Figure 1. Below is the code I used to create a collection of Product objects. I have shortened the code in this blog, but you can get the full source code for this sample by following the instructions at the bottom of this blog entry. List<Product> coll = new List<Product>();Product prod; prod = new Product()  { ProductName = "From Zero to HTML 5 in 60 Minutes",     ProductId = 1 };coll.Add(prod);prod = new Product()   { ProductName = "Architecting Applications …",     ProductId = 2 };coll.Add(prod);prod = new Product()  { ProductName = "Introduction to Windows Phone Development",    ProductId = 3 };coll.Add(prod);prod = new Product()   { ProductName = "Architecting a Business  …",     ProductId = 4 };coll.Add(prod);......   Figure 1: Class without overriding ToString() Now, go back to the Product class and add an override of the ToString() method as shown in the code listed below: public class Product{  public string ProductName { get; set; }  public int ProductId { get; set; }   public override string ToString()  {    return ProductName;  }} In this simple sample, I am just returning the ProductName property. However, you can create a whole string of information if you wish to display more data in your data tips. Just concatenate any properties you want from your class and return that string. When you now run the application and hover over the collection object you will now see something that looks like Figure 2. Figure 2: Overriding ToString() in your Class Another place the ToString() override comes in handy is if you forget to use a DisplayMemberPath in your ListBox or ComboBox. The ToString() method is called automatically when a class is bound to a list control. Summary You should always override the ToString() method in your classes as this will help you when debugging your application. Seeing relevant data immediately in the data tip without having to drill down one more layer and maybe scroll through a complete list of properties should help speed up your development process. NOTE: You can download the sample code for this article by visiting my website at http://www.pdsa.com/downloads. Select “Tips & Tricks”, then select “Override ToString” from the drop down list.  

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• SQL Server Transaction Marks: Restoring multiple databases to a common relative point

  - by Mladen Prajdic

  We’re all familiar with the ability to restore a database to point in time using the RESTORE WITH STOPAT statement. But what if we have multiple databases that are accessed from one application or are modifying each other? And over multiple instances? And all databases have different workloads? And we want to restore all of the databases to some known common relative point? The catch here is that this common relative point isn’t the same point in time for all databases. This common relative point in time might be now in DB1, now-1 hour in DB2 and yesterday in DB3. And we don’t know the exact times. Let me introduce you to Transaction Marks. When we run a marked transaction using the WITH MARK option a flag is set in the transaction log and a row is added to msdb..logmarkhistory table. When restoring a transaction log backup we can restore to either before or after that marked transaction. The best thing is that we don’t even need to have one database modifying another database. All we have to do is use a marked transaction with the same name in different database. Let’s see how this works with an example. The code comments say what’s going on. USE master GOCREATE DATABASE TestTxMark1GOUSE TestTxMark1GOCREATE TABLE TestTable1( ID INT, VALUE UNIQUEIDENTIFIER) -- insert some data into the table so we can have a starting pointINSERT INTO TestTable1SELECT ROW_NUMBER() OVER(ORDER BY number) AS RN, NULLFROM master..spt_valuesORDER BY RNSELECT *FROM TestTable1GO-- TAKE A FULL BACKUP of the databseBACKUP DATABASE TestTxMark1 TO DISK = 'c:\TestTxMark1.bak'GO USE master GOCREATE DATABASE TestTxMark2GOUSE TestTxMark2GOCREATE TABLE TestTable2( ID INT, VALUE UNIQUEIDENTIFIER)-- insert some data into the table so we can have a starting pointINSERT INTO TestTable2SELECT ROW_NUMBER() OVER(ORDER BY number) AS RN, NEWID()FROM master..spt_valuesORDER BY RNSELECT *FROM TestTable2GO-- TAKE A FULL BACKUP of our databseBACKUP DATABASE TestTxMark2 TO DISK = 'c:\TestTxMark2.bak'GO -- start a marked transaction that modifies both databasesBEGIN TRAN TxDb WITH MARK -- update values from NULL to random value UPDATE TestTable1 SET VALUE = NEWID(); -- update first 100 values from random value -- to NULL in different DB UPDATE TestTxMark2.dbo.TestTable2 SET VALUE = NULL WHERE ID <= 100;COMMITGO     -- some time goes by here -- with various database activity... -- We see two entries for marks in each database. -- This is just informational and has no bearing on the restore itself.SELECT * FROM msdb..logmarkhistory USE masterGO-- create a log backup to restore to mark pointBACKUP LOG TestTxMark1 TO DISK = 'c:\TestTxMark1.trn'GO-- drop the database so we can restore it backDROP DATABASE TestTxMark1GO USE masterGO-- create a log backup to restore to mark pointBACKUP LOG TestTxMark2 TO DISK = 'c:\TestTxMark2.trn'GO-- drop the database so we can restore it backDROP DATABASE TestTxMark2GO -- RESTORE THE DATABASE BACK BEFORE OUR TRANSACTION-- restore the full backup RESTORE DATABASE TestTxMark1 FROM DISK = 'c:\TestTxMark1.bak' WITH NORECOVERY;-- restore the log backup to the transaction markRESTORE LOG TestTxMark1 FROM DISK = 'c:\TestTxMark1.trn' WITH RECOVERY, -- recover to state before the transaction STOPBEFOREMARK = 'TxDb'; -- recover to state after the transaction -- STOPATMARK = 'TxDb';GO -- RESTORE THE DATABASE BACK BEFORE OUR TRANSACTION-- restore the full backup RESTORE DATABASE TestTxMark2 FROM DISK = 'c:\TestTxMark2.bak' WITH NORECOVERY;-- restore the log backup to the transaction markRESTORE LOG TestTxMark2 FROM DISK = 'c:\TestTxMark2.trn' WITH RECOVERY, -- recover to state before the transaction STOPBEFOREMARK = 'TxDb'; -- recover to state after the transaction -- STOPATMARK = 'TxDb';GO USE TestTxMark1-- we restored to time before the transaction -- so we have NULL values in our tableSELECT * FROM TestTable1 USE TestTxMark2-- we restored to time before the transaction -- so we DON'T have NULL values in our tableSELECT * FROM TestTable2   Transaction marks can be used like a crude sync mechanism for cross database operations. With them we can mark our databases with a common “restore to” point so we know we have a valid state between all databases to restore to.

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• How to raycast select a scaled OBB?

  - by user3254944

  I have the OBB picking code to select an OBB with code inspired from Real time Rendering 3 and opengl-tutorial.org. I can successfully select objects that have been moved or rotated. However, I cant correctly select an object that has been scaled. The bounding box scales right, but the I can only select the object in a thin strip on its center. How do I fix the checkForHits() function to allow it to read the scaling that I passed to it in the raycast matrix? void GLWidget::selectObjRaycast() { glm::vec2 mouse = (glm::vec2(mousePos.x(), mousePos.y()) / glm::vec2(this->width(), this->height())) * 2.0f - 1.0f; mouse.y *= -1; glm::mat4 toWorld = glm::inverse(ProjectionM * ViewM); glm::vec4 from = toWorld * glm::vec4(mouse, -1.0f, 1.0f); glm::vec4 to = toWorld * glm::vec4(mouse, 1.0f, 1.0f); from /= from.w; to /= to.w; fromAABB = glm::vec3(from); toAABB = glm::normalize(glm::vec3(to - from)); checkForHits(); } void GLWidget::checkForHits() { for (int i = 0; i < myWin.myEtc->allObj.size(); ++i) //check for hits on each obj's bb { bool miss = 0; float tMin = 0.0f; float tMax = 100000.0f; glm::vec3 bbPos(myWin.myEtc->allObj[i]->raycastM[3].x, myWin.myEtc->allObj[i]->raycastM[3].y, myWin.myEtc->allObj[i]->raycastM[3].z); glm::vec3 delta = bbPos - fromAABB; for (int j = 0; j < 3; ++j) { glm::vec3 axis(myWin.myEtc->allObj[i]->raycastM[j].x, myWin.myEtc->allObj[i]->raycastM[j].y, myWin.myEtc->allObj[i]->raycastM[j].z); float e = glm::dot(axis, delta); float f = glm::dot(toAABB, axis); if (fabs(f) > 0.001f) { float t1 = (e + myWin.myEtc->allObj[i]->bbMin[j]) / f; float t2 = (e + myWin.myEtc->allObj[i]->bbMax[j]) / f; if (t1 > t2) { float w = t1; t1 = t2; t2 = w; } if (t2 < tMax) tMax = t2; if (t1 > tMin) tMin = t1; if (tMax < tMin) miss = 1; } else { if (-e + myWin.myEtc->allObj[i]->bbMin[j] > 0.0f || -e + myWin.myEtc->allObj[i]->bbMax[j] < 0.0f) miss = 1; } } if (miss == 0) { intersection_distance = tMin; myWin.myEtc->sel.push_back(myWin.myEtc->allObj[i]); myWin.myEtc->allObj[i]->highlight = myWin.myGLHelp->highlight; break; } } } void Object::render(glm::mat4 PV) { scaleM = glm::scale(glm::mat4(), s->val_3); r_quat = glm::quat(glm::radians(r->val_3)); rotationM = glm::toMat4(r_quat); translationM = glm::translate(glm::mat4(), t->val_3); transLocal1M = glm::translate(glm::mat4(), -rsPivot->val_3); transLocal2M = glm::translate(glm::mat4(), rsPivot->val_3); raycastM = translationM * transLocal2M * rotationM * scaleM * transLocal1M; // MVP = PV * translationM * transLocal2M * rotationM * scaleM * transLocal1M; }

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• How to fix OpenGL Co-ordinate System in SFML?

  - by Marc Alexander Reed

  My OpenGL setup is somehow configured to work like so: (-1, 1) (0, 1) (1, 1) (-1, 0) (0, 0) (1, 0) (-1, -1) (0, -1) (1, -1) How do I configure it so that it works like so: (0, 0) (SW/2, 0) (SW, 0) (0, SH/2) (SW/2, SH/2) (SW, SH/2) (0, SH) (SW/2, SH) (SW/2, SH) SW as Screen Width. SH as Screen Height. This solution would have to fix the problem of I can't translate significantly(1) on the Z axis. Depth doesn't seem to be working either. The Perspective code I'm using is that of my WORKING GLUT OpenGL code which has a cool 3d grid and camera system etc. But my OpenGL setup doesn't seem to work with SFML. Help me guys. :( Thanks in advance. :) #include <SFML/Window.hpp> #include <SFML/Graphics.hpp> #include <SFML/Audio.hpp> #include <SFML/Network.hpp> #include <SFML/OpenGL.hpp> #include "ResourcePath.hpp" //Mac-only #define _USE_MATH_DEFINES #include <cmath> double screen_width = 640.f; double screen_height = 480.f; int main (int argc, const char **argv) { sf::ContextSettings settings; settings.depthBits = 24; settings.stencilBits = 8; settings.antialiasingLevel = 2; sf::Window window(sf::VideoMode(screen_width, screen_height, 32), "SFML OpenGL", sf::Style::Close, settings); window.setActive(); glEnable(GL_DEPTH_TEST); glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); glEnable(GL_NORMALIZE); glEnable(GL_COLOR_MATERIAL); glShadeModel(GL_SMOOTH); glViewport(0, 0, screen_width, screen_height); glMatrixMode(GL_PROJECTION); glLoadIdentity(); //glOrtho(0.0f, screen_width, screen_height, 0.0f, -100.0f, 100.0f); gluPerspective(45.0f, (double) screen_width / (double) screen_height , 0.f, 100.f); glClearColor(0.f, 0.f, 1.f, 0.f); //blue while (window.isOpen()) { sf::Event event; while (window.pollEvent(event)) { switch (event.type) { case sf::Event::Closed: window.close(); break; } switch (event.key.code) { case sf::Keyboard::Escape: window.close(); break; case 'W': break; case 'S': break; case 'A': break; case 'D': break; } } glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glTranslatef(0.f, 0.f, 0.f); glPushMatrix(); glBegin(GL_QUADS); glColor3f(1.f, 0.f, 0.f); glVertex3f(-1.f, 1.f, 0.f); glColor3f(0.f, 1.f, 0.f); glVertex3f(1.f, 1.f, 0.f); glColor3f(1.f, 0.f, 1.f); glVertex3f(1.f, -1.f, 0.f); glColor3f(0.f, 0.f, 1.f); glVertex3f(-1.f, -1.f, 0.f); glEnd(); glPopMatrix(); window.display(); } return EXIT_SUCCESS; }

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