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  • How do I get around this lambda expression outer variable issue?

    - by panamack
    I'm playing with PropertyDescriptor and ICustomTypeDescriptor (still) trying to bind a WPF DataGrid to an object, for which the data is stored in a Dictionary. Since if you pass WPF DataGrid a list of Dictionary objects it will auto generate columns based on the public properties of a dictionary (Comparer, Count, Keys and Values) my Person subclasses Dictionary and implements ICustomTypeDescriptor. ICustomTypeDescriptor defines a GetProperties method which returns a PropertyDescriptorCollection. PropertyDescriptor is abstract so you have to subclass it, I figured I'd have a constructor that took Func and an Action parameters that delegate the getting and setting of the values in the dictionary. I then create a PersonPropertyDescriptor for each Key in the dictionary like this: foreach (string s in this.Keys) { var descriptor = new PersonPropertyDescriptor( s, new Func<object>(() => { return this[s]; }), new Action<object>(o => { this[s] = o; })); propList.Add(descriptor); } The problem is that each property get's its own Func and Action but they all share the outer variable s so although the DataGrid autogenerates columns for "ID","FirstName","LastName", "Age", "Gender" they all get and set against "Gender" which is the final resting value of s in the foreach loop. How can I ensure that each delegate uses the desired dictionary Key, i.e. the value of s at the time the Func/Action is instantiated? Much obliged. Here's the rest of my idea, I'm just experimenting here these are not 'real' classes... // DataGrid binds to a People instance public class People : List<Person> { public People() { this.Add(new Person()); } } public class Person : Dictionary<string, object>, ICustomTypeDescriptor { private static PropertyDescriptorCollection descriptors; public Person() { this["ID"] = "201203"; this["FirstName"] = "Bud"; this["LastName"] = "Tree"; this["Age"] = 99; this["Gender"] = "M"; } //... other ICustomTypeDescriptor members... public PropertyDescriptorCollection GetProperties() { if (descriptors == null) { var propList = new List<PropertyDescriptor>(); foreach (string s in this.Keys) { var descriptor = new PersonPropertyDescriptor( s, new Func<object>(() => { return this[s]; }), new Action<object>(o => { this[s] = o; })); propList.Add(descriptor); } descriptors = new PropertyDescriptorCollection(propList.ToArray()); } return descriptors; } //... other other ICustomTypeDescriptor members... } public class PersonPropertyDescriptor : PropertyDescriptor { private Func<object> getFunc; private Action<object> setAction; public PersonPropertyDescriptor(string name, Func<object> getFunc, Action<object> setAction) : base(name, null) { this.getFunc = getFunc; this.setAction = setAction; } // other ... PropertyDescriptor members... public override object GetValue(object component) { return getFunc(); } public override void SetValue(object component, object value) { setAction(value); } }

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  • Novo Suporte para Combinação e Minificação de Arquivos JavaScript e CSS (Série de posts sobre a ASP.NET 4.5)

    - by Leniel Macaferi
    Este é o sexto post de uma série de posts que estou escrevendo sobre a ASP.NET 4.5. Os próximos lançamentos do .NET e Visual Studio incluem vários novos e ótimos recursos e capacidades. Com a ASP.NET 4.5 você vai ver um monte de melhorias realmente emocionantes em formulários da Web ( Web Forms ) e MVC - assim como no núcleo da base de código da ASP.NET, no qual estas tecnologias são baseadas. O post de hoje cobre um pouco do trabalho que estamos realizando para adicionar suporte nativo para combinação e minificação de arquivos JavaScript e CSS dentro da ASP.NET - o que torna mais fácil melhorar o desempenho das aplicações. Este recurso pode ser utilizado por todas as aplicações ASP.NET, incluindo tanto a ASP.NET MVC quanto a ASP.NET Web Forms. Noções básicas sobre Combinação e Minificação Como mais e mais pessoas usando dispositivos móveis para navegar na web, está se tornando cada vez mais importante que os websites e aplicações que construímos tenham um bom desempenho neles. Todos nós já tentamos carregar sites em nossos smartphones - apenas para, eventualmente, desistirmos em meio à frustração porque os mesmos são carregados lentamente através da lenta rede celular. Se o seu site/aplicação carrega lentamente assim, você está provavelmente perdendo clientes em potencial por causa do mau desempenho/performance. Mesmo com máquinas desktop poderosas, o tempo de carregamento do seu site e o desempenho percebido podem contribuir enormemente para a percepção do cliente. A maioria dos websites hoje em dia são construídos com múltiplos arquivos de JavaScript e CSS para separar o código e para manter a base de código coesa. Embora esta seja uma boa prática do ponto de vista de codificação, muitas vezes isso leva a algumas consequências negativas no tocante ao desempenho geral do site. Vários arquivos de JavaScript e CSS requerem múltiplas solicitações HTTP provenientes do navegador - o que pode retardar o tempo de carregamento do site.  Exemplo Simples A seguir eu abri um site local no IE9 e gravei o tráfego da rede usando as ferramentas do desenvolvedor nativas do IE (IE Developer Tools) que podem ser acessadas com a tecla F12. Como mostrado abaixo, o site é composto por 5 arquivos CSS e 4 arquivos JavaScript, os quais o navegador tem que fazer o download. Cada arquivo é solicitado separadamente pelo navegador e retornado pelo servidor, e o processo pode levar uma quantidade significativa de tempo proporcional ao número de arquivos em questão. Combinação A ASP.NET está adicionando um recurso que facilita a "união" ou "combinação" de múltiplos arquivos CSS e JavaScript em menos solicitações HTTP. Isso faz com que o navegador solicite muito menos arquivos, o que por sua vez reduz o tempo que o mesmo leva para buscá-los. A seguir está uma versão atualizada do exemplo mostrado acima, que tira vantagem desta nova funcionalidade de combinação de arquivos (fazendo apenas um pedido para JavaScript e um pedido para CSS): O navegador agora tem que enviar menos solicitações ao servidor. O conteúdo dos arquivos individuais foram combinados/unidos na mesma resposta, mas o conteúdo dos arquivos permanece o mesmo - por isso o tamanho do arquivo geral é exatamente o mesmo de antes da combinação (somando o tamanho dos arquivos separados). Mas note como mesmo em uma máquina de desenvolvimento local (onde a latência da rede entre o navegador e o servidor é mínima), o ato de combinar os arquivos CSS e JavaScript ainda consegue reduzir o tempo de carregamento total da página em quase 20%. Em uma rede lenta a melhora de desempenho seria ainda maior. Minificação A próxima versão da ASP.NET também está adicionando uma nova funcionalidade que facilita reduzir ou "minificar" o tamanho do download do conteúdo. Este é um processo que remove espaços em branco, comentários e outros caracteres desnecessários dos arquivos CSS e JavaScript. O resultado é arquivos menores, que serão enviados e carregados no navegador muito mais rapidamente. O gráfico a seguir mostra o ganho de desempenho que estamos tendo quando os processos de combinação e minificação dos arquivos são usados ??em conjunto: Mesmo no meu computador de desenvolvimento local (onde a latência da rede é mínima), agora temos uma melhoria de desempenho de 40% a partir de onde originalmente começamos. Em redes lentas (e especialmente com clientes internacionais), os ganhos seriam ainda mais significativos. Usando Combinação e Minificação de Arquivos dentro da ASP.NET A próxima versão da ASP.NET torna realmente fácil tirar proveito da combinação e minificação de arquivos dentro de projetos, possibilitando ganhos de desempenho como os que foram mostrados nos cenários acima. A forma como ela faz isso, te permite evitar a execução de ferramentas personalizadas/customizadas, como parte do seu processo de construção da aplicação/website - ao invés disso, a ASP.NET adicionou suporte no tempo de execução/runtime para que você possa executar a combinação/minificação dos arquivos dinamicamente (cacheando os resultados para ter certeza de que a performance seja realmente satisfatória). Isto permite uma experiência de desenvolvimento realmente limpa e torna super fácil começar a tirar proveito destas novas funcionalidades. Vamos supor que temos um projeto simples com 4 arquivos JavaScript e 6 arquivos CSS: Combinando e Minificando os Arquivos CSS Digamos que você queira referenciar em uma página todas as folhas de estilo que estão dentro da pasta "Styles" mostrada acima. Hoje você tem que adicionar múltiplas referências para os arquivos CSS para obter todos eles - o que se traduziria em seis requisições HTTP separadas: O novo recurso de combinação/minificação agora permite que você combine e minifique todos os arquivos CSS da pasta Styles - simplesmente enviando uma solicitação de URL para a pasta (neste caso, "styles"), com um caminho adicional "/css" na URL. Por exemplo:    Isso fará com que a ASP.NET verifique o diretório, combine e minifique os arquivos CSS que estiverem dentro da pasta, e envie uma única resposta HTTP para o navegador com todo o conteúdo CSS. Você não precisa executar nenhuma ferramenta ou pré-processamento para obter esse comportamento. Isso te permite separar de maneira limpa seus estilos em arquivos CSS separados e condizentes com cada funcionalidade da aplicação mantendo uma experiência de desenvolvimento extremamente limpa - e mesmo assim você não terá um impacto negativo de desempenho no tempo de execução da aplicação. O designer do Visual Studio também vai honrar a lógica de combinação/minificação - assim você ainda terá uma experiência WYSWIYG no designer dentro VS. Combinando e Minificando os Arquivos JavaScript Como a abordagem CSS mostrada acima, se quiséssemos combinar e minificar todos os nossos arquivos de JavaScript em uma única resposta, poderíamos enviar um pedido de URL para a pasta (neste caso, "scripts"), com um caminho adicional "/js":   Isso fará com que a ASP.NET verifique o diretório, combine e minifique os arquivos com extensão .js dentro dele, e envie uma única resposta HTTP para o navegador com todo o conteúdo JavaScript. Mais uma vez - nenhuma ferramenta customizada ou etapas de construção foi necessária para obtermos esse comportamento. Este processo funciona em todos os navegadores. Ordenação dos Arquivos dentro de um Pacote Por padrão, quando os arquivos são combinados pela ASP.NET, eles são ordenados em ordem alfabética primeiramente, exatamente como eles são mostrados no Solution Explorer. Em seguida, eles são automaticamente reorganizados de modo que as bibliotecas conhecidas e suas extensões personalizadas, tais como jQuery, MooTools e Dojo sejam carregadas antes de qualquer outra coisa. Assim, a ordem padrão para a combinação dos arquivos da pasta Scripts, como a mostrada acima será: jquery-1.6.2.js jquery-ui.js jquery.tools.js a.js Por padrão, os arquivos CSS também são classificados em ordem alfabética e depois são reorganizados de forma que o arquivo reset.css e normalize.css (se eles estiverem presentes na pasta) venham sempre antes de qualquer outro arquivo. Assim, o padrão de classificação da combinação dos arquivos da pasta "Styles", como a mostrada acima será: reset.css content.css forms.css globals.css menu.css styles.css A ordenação/classificação é totalmente personalizável, e pode ser facilmente alterada para acomodar a maioria dos casos e qualquer padrão de nomenclatura que você prefira. O objetivo com a experiência pronta para uso, porém, é ter padrões inteligentes que você pode simplesmente usar e ter sucesso com os mesmos. Qualquer número de Diretórios/Subdiretórios é Suportado No exemplo acima, nós tivemos apenas uma única pasta "Scripts" e "Styles" em nossa aplicação. Isso funciona para alguns tipos de aplicação (por exemplo, aplicações com páginas simples). Muitas vezes, porém, você vai querer ter múltiplos pacotes/combinações de arquivos CSS/JS dentro de sua aplicação - por exemplo: um pacote "comum", que tem o núcleo dos arquivos JS e CSS que todas as páginas usam, e então arquivos específicos para páginas ou seções que não são utilizados globalmente. Você pode usar o suporte à combinação/minificação em qualquer número de diretórios ou subdiretórios em seu projeto - isto torna mais fácil estruturar seu código de forma a maximizar os benefícios da combinação/minificação dos arquivos. Cada diretório por padrão pode ser acessado como um pacote separado e endereçável através de uma URL.  Extensibilidade para Combinação/Minificação de Arquivos O suporte da ASP.NET para combinar e minificar é construído com extensibilidade em mente e cada parte do processo pode ser estendido ou substituído. Regras Personalizadas Além de permitir a abordagem de empacotamento - baseada em diretórios - que vem pronta para ser usada, a ASP.NET também suporta a capacidade de registrar pacotes/combinações personalizadas usando uma nova API de programação que estamos expondo.  O código a seguir demonstra como você pode registrar um "customscript" (script personalizável) usando código dentro da classe Global.asax de uma aplicação. A API permite que você adicione/remova/filtre os arquivos que farão parte do pacote de maneira muito granular:     O pacote personalizado acima pode ser referenciado em qualquer lugar dentro da aplicação usando a referência de <script> mostrada a seguir:     Processamento Personalizado Você também pode substituir os pacotes padrão CSS e JavaScript para suportar seu próprio processamento personalizado dos arquivos do pacote (por exemplo: regras personalizadas para minificação, suporte para Saas, LESS ou sintaxe CoffeeScript, etc). No exemplo mostrado a seguir, estamos indicando que queremos substituir as transformações nativas de minificação com classes MyJsTransform e MyCssTransform personalizadas. Elas são subclasses dos respectivos minificadores padrão para CSS e JavaScript, e podem adicionar funcionalidades extras:     O resultado final desta extensibilidade é que você pode se plugar dentro da lógica de combinação/minificação em um nível profundo e fazer algumas coisas muito legais com este recurso. Vídeo de 2 Minutos sobre Combinação e Minificacão de Arquivos em Ação Mads Kristensen tem um ótimo vídeo de 90 segundo (em Inglês) que demonstra a utilização do recurso de Combinação e Minificação de Arquivos. Você pode assistir o vídeo de 90 segundos aqui. Sumário O novo suporte para combinação e minificação de arquivos CSS e JavaScript dentro da próxima versão da ASP.NET tornará mais fácil a construção de aplicações web performáticas. Este recurso é realmente fácil de usar e não requer grandes mudanças no seu fluxo de trabalho de desenvolvimento existente. Ele também suporta uma rica API de extensibilidade que permite a você personalizar a lógica da maneira que você achar melhor. Você pode facilmente tirar vantagem deste novo suporte dentro de aplicações baseadas em ASP.NET MVC e ASP.NET Web Forms. Espero que ajude, Scott P.S. Além do blog, eu uso o Twitter para disponibilizar posts rápidos e para compartilhar links.Lidar com o meu Twitter é: @scottgu Texto traduzido do post original por Leniel Macaferi. google_ad_client = "pub-8849057428395760"; /* 728x90, created 2/15/09 */ google_ad_slot = "4706719075"; google_ad_width = 728; google_ad_height = 90;

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  • Silverlight for Windows Embedded tutorial (step 6)

    - by Valter Minute
    In this tutorial step we will develop a very simple clock application that may be used as a screensaver on our devices and will allow us to discover a new feature of Silverlight for Windows Embedded (transforms) and how to use an “old” feature of Windows CE (timers) inside a Silverlight for Windows Embedded application. Let’s start with some XAML, as usual: <UserControl xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Width="640" Height="480" FontSize="18" x:Name="Clock">   <Canvas x:Name="LayoutRoot" Background="#FF000000"> <Grid Height="24" Width="150" Canvas.Left="320" Canvas.Top="234" x:Name="SecondsHand" Background="#FFFF0000"> <TextBlock Text="Seconds" TextWrapping="Wrap" Width="50" HorizontalAlignment="Right" VerticalAlignment="Center" x:Name="SecondsText" Foreground="#FFFFFFFF" TextAlignment="Right" Margin="2,2,2,2"/> </Grid> <Grid Height="24" x:Name="MinutesHand" Width="100" Background="#FF00FF00" Canvas.Left="320" Canvas.Top="234"> <TextBlock HorizontalAlignment="Right" x:Name="MinutesText" VerticalAlignment="Center" Width="50" Text="Minutes" TextWrapping="Wrap" Foreground="#FFFFFFFF" TextAlignment="Right" Margin="2,2,2,2"/> </Grid> <Grid Height="24" x:Name="HoursHand" Width="50" Background="#FF0000FF" Canvas.Left="320" Canvas.Top="234"> <TextBlock HorizontalAlignment="Right" x:Name="HoursText" VerticalAlignment="Center" Width="50" Text="Hours" TextWrapping="Wrap" Foreground="#FFFFFFFF" TextAlignment="Right" Margin="2,2,2,2"/> </Grid> </Canvas> </UserControl> This XAML file defines three grid panels, one for each hand of our clock (we are implementing an analog clock using one of the most advanced technologies of the digital world… how cool is that?). Inside each hand we put a TextBlock that will be used to display the current hour, minute, second inside the dial (you can’t do that on plain old analog clocks, but it looks nice). As usual we use XAML2CPP to generate the boring part of our code. We declare a class named “Clock” and derives from the TClock template that XAML2CPP has declared for us. class Clock : public TClock<Clock> { ... }; Our WinMain function is more or less the same we used in all the previous samples. It initializes the XAML runtime, create an instance of our class, initialize it and shows it as a dialog: int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow) { if (!XamlRuntimeInitialize()) return -1;   HRESULT retcode;   IXRApplicationPtr app; if (FAILED(retcode=GetXRApplicationInstance(&app))) return -1; Clock clock;   if (FAILED(clock.Init(hInstance,app))) return -1;     UINT exitcode;   if (FAILED(clock.GetVisualHost()->StartDialog(&exitcode))) return -1;   return exitcode; } Silverlight for Windows Embedded provides a lot of features to implement our UI, but it does not provide timers. How we can update our clock if we don’t have a timer feature? We just use plain old Windows timers, as we do in “regular” Windows CE applications! To use a timer in WinCE we should declare an id for it: #define IDT_CLOCKUPDATE 0x12341234 We also need an HWND that will be used to receive WM_TIMER messages. Our Silverlight for Windows Embedded page is “hosted” inside a GWES Window and we can retrieve its handle using the GetContainerHWND function of our VisualHost object. Let’s see how this is implemented inside our Clock class’ Init method: HRESULT Init(HINSTANCE hInstance,IXRApplication* app) { HRESULT retcode;   if (FAILED(retcode=TClock<Clock>::Init(hInstance,app))) return retcode;   // create the timer user to update the clock HWND clockhwnd;   if (FAILED(GetVisualHost()->GetContainerHWND(&clockhwnd))) return -1;   timer=SetTimer(clockhwnd,IDT_CLOCKUPDATE,1000,NULL); return 0; } We use SetTimer to create a new timer and GWES will send a WM_TIMER to our window every second, giving us a chance to update our clock. That sounds great… but how could we handle the WM_TIMER message if we didn’t implement a window procedure for our window? We have to move a step back and look how a visual host is created. This code is generated by XAML2CPP and is inside xaml2cppbase.h: virtual HRESULT CreateHost(HINSTANCE hInstance,IXRApplication* app) { HRESULT retcode; XRWindowCreateParams wp;   ZeroMemory(&wp, sizeof(XRWindowCreateParams)); InitWindowParms(&wp);   XRXamlSource xamlsrc;   SetXAMLSource(hInstance,&xamlsrc); if (FAILED(retcode=app->CreateHostFromXaml(&xamlsrc, &wp, &vhost))) return retcode;   if (FAILED(retcode=vhost->GetRootElement(&root))) return retcode; return S_OK; } As you can see the CreateHostFromXaml function of IXRApplication accepts a structure named XRWindowCreateParams that control how the “plain old” GWES Window is created by the runtime. This structure is initialized inside the InitWindowParm method: // Initializes Windows parameters, can be overridden in the user class to change its appearance virtual void InitWindowParms(XRWindowCreateParams* wp) { wp->Style = WS_OVERLAPPED; wp->pTitle = windowtitle; wp->Left = 0; wp->Top = 0; } This method set up the window style, title and position. But the XRWindowCreateParams contains also other fields and, since the function is declared as virtual, we could initialize them inside our version of InitWindowParms: // add hook procedure to the standard windows creation parms virtual void InitWindowParms(XRWindowCreateParams* wp) { TClock<Clock>::InitWindowParms(wp);   wp->pHookProc=StaticHostHookProc; wp->pvUserParam=this; } This method calls the base class implementation (useful to not having to re-write some code, did I told you that I’m quite lazy?) and then initializes the pHookProc and pvUserParam members of the XRWindowsCreateParams structure. Those members will allow us to install a “hook” procedure that will be called each time the GWES window “hosting” our Silverlight for Windows Embedded UI receives a message. We can declare a hook procedure inside our Clock class: // static hook procedure static BOOL CALLBACK StaticHostHookProc(VOID* pv,HWND hwnd,UINT Msg,WPARAM wParam,LPARAM lParam,LRESULT* pRetVal) { ... } You should notice two things here. First that the function is declared as static. This is required because a non-static function has a “hidden” parameters, that is the “this” pointer of our object. Having an extra parameter is not allowed for the type defined for the pHookProc member of the XRWindowsCreateParams struct and so we should implement our hook procedure as static. But in a static procedure we will not have a this pointer. How could we access the data member of our class? Here’s the second thing to notice. We initialized also the pvUserParam of the XRWindowsCreateParams struct. We set it to our this pointer. This value will be passed as the first parameter of the hook procedure. In this way we can retrieve our this pointer and use it to call a non-static version of our hook procedure: // static hook procedure static BOOL CALLBACK StaticHostHookProc(VOID* pv,HWND hwnd,UINT Msg,WPARAM wParam,LPARAM lParam,LRESULT* pRetVal) { return ((Clock*)pv)->HostHookProc(hwnd,Msg,wParam,lParam,pRetVal); } Inside our non-static hook procedure we will have access to our this pointer and we will be able to update our clock: // hook procedure (handles timers) BOOL HostHookProc(HWND hwnd,UINT Msg,WPARAM wParam,LPARAM lParam,LRESULT* pRetVal) { switch (Msg) { case WM_TIMER: if (wParam==IDT_CLOCKUPDATE) UpdateClock(); *pRetVal=0; return TRUE; } return FALSE; } The UpdateClock member function will update the text inside our TextBlocks and rotate the hands to reflect current time: // udates Hands positions and labels HRESULT UpdateClock() { SYSTEMTIME time; HRESULT retcode;   GetLocalTime(&time);   //updates the text fields TCHAR timebuffer[32];   _itow(time.wSecond,timebuffer,10);   SecondsText->SetText(timebuffer);   _itow(time.wMinute,timebuffer,10);   MinutesText->SetText(timebuffer);   _itow(time.wHour,timebuffer,10);   HoursText->SetText(timebuffer);   if (FAILED(retcode=RotateHand(((float)time.wSecond)*6-90,SecondsHand))) return retcode;   if (FAILED(retcode=RotateHand(((float)time.wMinute)*6-90,MinutesHand))) return retcode;   if (FAILED(retcode=RotateHand(((float)(time.wHour%12))*30-90,HoursHand))) return retcode;   return S_OK; } The function retrieves current time, convert hours, minutes and seconds to strings and display those strings inside the three TextBlocks that we put inside our clock hands. Then it rotates the hands to position them at the right angle (angles are in degrees and we have to subtract 90 degrees because 0 degrees means horizontal on Silverlight for Windows Embedded and usually a clock 0 is in the top position of the dial. The code of the RotateHand function uses transforms to rotate our clock hands on the screen: // rotates a Hand HRESULT RotateHand(float angle,IXRFrameworkElement* Hand) { HRESULT retcode; IXRRotateTransformPtr rotatetransform; IXRApplicationPtr app;   if (FAILED(retcode=GetXRApplicationInstance(&app))) return retcode;   if (FAILED(retcode=app->CreateObject(IID_IXRRotateTransform,&rotatetransform))) return retcode;     if (FAILED(retcode=rotatetransform->SetAngle(angle))) return retcode;   if (FAILED(retcode=rotatetransform->SetCenterX(0.0))) return retcode;   float height;   if (FAILED(retcode==Hand->GetActualHeight(&height))) return retcode;   if (FAILED(retcode=rotatetransform->SetCenterY(height/2))) return retcode; if (FAILED(retcode=Hand->SetRenderTransform(rotatetransform))) return retcode;   return S_OK; } It creates a IXRotateTransform object, set its rotation angle and origin (the default origin is at the top-left corner of our Grid panel, we move it in the vertical center to keep the hand rotating around a single point in a more “clock like” way. Then we can apply the transform to our UI object using SetRenderTransform. Every UI element (derived from IXRFrameworkElement) can be rotated! And using different subclasses of IXRTransform also moved, scaled, skewed and distorted in many ways. You can also concatenate multiple transforms and apply them at once suing a IXRTransformGroup object. The XAML engine uses vector graphics and object will not look “pixelated” when they are rotated or scaled. As usual you can download the code here: http://cid-9b7b0aefe3514dc5.skydrive.live.com/self.aspx/.Public/Clock.zip If you read up to (down to?) this point you seem to be interested in Silverlight for Windows Embedded. If you want me to discuss some specific topic, please feel free to point it out in the comments! Technorati Tags: Silverlight for Windows Embedded,Windows CE

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  • C#/.NET Little Wonders: The EventHandler and EventHandler&lt;TEventArgs&gt; delegates

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. In the last two weeks, we examined the Action family of delegates (and delegates in general), and the Func family of delegates and how they can be used to support generic, reusable algorithms and classes. So this week, we are going to look at a handy pair of delegates that can be used to eliminate the need for defining custom delegates when creating events: the EventHandler and EventHandler<TEventArgs> delegates. Events and delegates Before we begin, let’s quickly consider events in .NET.  According to the MSDN: An event in C# is a way for a class to provide notifications to clients of that class when some interesting thing happens to an object. So, basically, you can create an event in a type so that users of that type can subscribe to notifications of things of interest.  How is this different than some of the delegate programming that we talked about in the last two weeks?  Well, you can think of an event as a special access modifier on a delegate.  Some differences between the two are: Events are a special access case of delegates They behave much like delegates instances inside the type they are declared in, but outside of that type they can only be (un)subscribed to. Events can specify add/remove behavior explicitly If you want to do additional work when someone subscribes or unsubscribes to an event, you can specify the add and remove actions explicitly. Events have access modifiers, but these only specify the access level of those who can (un)subscribe A public event, for example, means anyone can (un)subscribe, but it does not mean that anyone can raise (invoke) the event directly.  Events can only be raised by the type that contains them In contrast, if a delegate is visible, it can be invoked outside of the object (not even in a sub-class!). Events tend to be for notifications only, and should be treated as optional Semantically speaking, events typically don’t perform work on the the class directly, but tend to just notify subscribers when something of note occurs. My basic rule-of-thumb is that if you are just wanting to notify any listeners (who may or may not care) that something has happened, use an event.  However, if you want the caller to provide some function to perform to direct the class about how it should perform work, make it a delegate. Declaring events using custom delegates To declare an event in a type, we simply use the event keyword and specify its delegate type.  For example, let’s say you wanted to create a new TimeOfDayTimer that triggers at a given time of the day (as opposed to on an interval).  We could write something like this: 1: public delegate void TimeOfDayHandler(object source, ElapsedEventArgs e); 2:  3: // A timer that will fire at time of day each day. 4: public class TimeOfDayTimer : IDisposable 5: { 6: // Event that is triggered at time of day. 7: public event TimeOfDayHandler Elapsed; 8:  9: // ... 10: } The first thing to note is that the event is a delegate type, which tells us what types of methods may subscribe to it.  The second thing to note is the signature of the event handler delegate, according to the MSDN: The standard signature of an event handler delegate defines a method that does not return a value, whose first parameter is of type Object and refers to the instance that raises the event, and whose second parameter is derived from type EventArgs and holds the event data. If the event does not generate event data, the second parameter is simply an instance of EventArgs. Otherwise, the second parameter is a custom type derived from EventArgs and supplies any fields or properties needed to hold the event data. So, in a nutshell, the event handler delegates should return void and take two parameters: An object reference to the object that raised the event. An EventArgs (or a subclass of EventArgs) reference to event specific information. Even if your event has no additional information to provide, you are still expected to provide an EventArgs instance.  In this case, feel free to pass the EventArgs.Empty singleton instead of creating new instances of EventArgs (to avoid generating unneeded memory garbage). The EventHandler delegate Because many events have no additional information to pass, and thus do not require custom EventArgs, the signature of the delegates for subscribing to these events is typically: 1: // always takes an object and an EventArgs reference 2: public delegate void EventHandler(object sender, EventArgs e) It would be insane to recreate this delegate for every class that had a basic event with no additional event data, so there already exists a delegate for you called EventHandler that has this very definition!  Feel free to use it to define any events which supply no additional event information: 1: public class Cache 2: { 3: // event that is raised whenever the cache performs a cleanup 4: public event EventHandler OnCleanup; 5:  6: // ... 7: } This will handle any event with the standard EventArgs (no additional information).  But what of events that do need to supply additional information?  Does that mean we’re out of luck for subclasses of EventArgs?  That’s where the generic for of EventHandler comes into play… The generic EventHandler<TEventArgs> delegate Starting with the introduction of generics in .NET 2.0, we have a generic delegate called EventHandler<TEventArgs>.  Its signature is as follows: 1: public delegate void EventHandler<TEventArgs>(object sender, TEventArgs e) 2: where TEventArgs : EventArgs This is similar to EventHandler except it has been made generic to support the more general case.  Thus, it will work for any delegate where the first argument is an object (the sender) and the second argument is a class derived from EventArgs (the event data). For example, let’s say we wanted to create a message receiver, and we wanted it to have a few events such as OnConnected that will tell us when a connection is established (probably with no additional information) and OnMessageReceived that will tell us when a new message arrives (probably with a string for the new message text). So for OnMessageReceived, our MessageReceivedEventArgs might look like this: 1: public sealed class MessageReceivedEventArgs : EventArgs 2: { 3: public string Message { get; set; } 4: } And since OnConnected needs no event argument type defined, our class might look something like this: 1: public class MessageReceiver 2: { 3: // event that is called when the receiver connects with sender 4: public event EventHandler OnConnected; 5:  6: // event that is called when a new message is received. 7: public event EventHandler<MessageReceivedEventArgs> OnMessageReceived; 8:  9: // ... 10: } Notice, nowhere did we have to define a delegate to fit our event definition, the EventHandler and generic EventHandler<TEventArgs> delegates fit almost anything we’d need to do with events. Sidebar: Thread-safety and raising an event When the time comes to raise an event, we should always check to make sure there are subscribers, and then only raise the event if anyone is subscribed.  This is important because if no one is subscribed to the event, then the instance will be null and we will get a NullReferenceException if we attempt to raise the event. 1: // This protects against NullReferenceException... or does it? 2: if (OnMessageReceived != null) 3: { 4: OnMessageReceived(this, new MessageReceivedEventArgs(aMessage)); 5: } The above code seems to handle the null reference if no one is subscribed, but there’s a problem if this is being used in multi-threaded environments.  For example, assume we have thread A which is about to raise the event, and it checks and clears the null check and is about to raise the event.  However, before it can do that thread B unsubscribes to the event, which sets the delegate to null.  Now, when thread A attempts to raise the event, this causes the NullReferenceException that we were hoping to avoid! To counter this, the simplest best-practice method is to copy the event (just a multicast delegate) to a temporary local variable just before we raise it.  Since we are inside the class where this event is being raised, we can copy it to a local variable like this, and it will protect us from multi-threading since multicast delegates are immutable and assignments are atomic: 1: // always make copy of the event multi-cast delegate before checking 2: // for null to avoid race-condition between the null-check and raising it. 3: var handler = OnMessageReceived; 4: 5: if (handler != null) 6: { 7: handler(this, new MessageReceivedEventArgs(aMessage)); 8: } The very slight trade-off is that it’s possible a class may get an event after it unsubscribes in a multi-threaded environment, but this is a small risk and classes should be prepared for this possibility anyway.  For a more detailed discussion on this, check out this excellent Eric Lippert blog post on Events and Races. Summary Generic delegates give us a lot of power to make generic algorithms and classes, and the EventHandler delegate family gives us the flexibility to create events easily, without needing to redefine delegates over and over.  Use them whenever you need to define events with or without specialized EventArgs.   Tweet Technorati Tags: .NET, C#, CSharp, Little Wonders, Generics, Delegates, EventHandler

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  • C#/.NET Little Wonders: Use Cast() and TypeOf() to Change Sequence Type

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. We’ve seen how the Select() extension method lets you project a sequence from one type to a new type which is handy for getting just parts of items, or building new items.  But what happens when the items in the sequence are already the type you want, but the sequence itself is typed to an interface or super-type instead of the sub-type you need? For example, you may have a sequence of Rectangle stored in an IEnumerable<Shape> and want to consider it an IEnumerable<Rectangle> sequence instead.  Today we’ll look at two handy extension methods, Cast<TResult>() and OfType<TResult>() which help you with this task. Cast<TResult>() – Attempt to cast all items to type TResult So, the first thing we can do would be to attempt to create a sequence of TResult from every item in the source sequence.  Typically we’d do this if we had an IEnumerable<T> where we knew that every item was actually a TResult where TResult inherits/implements T. For example, assume the typical Shape example classes: 1: // abstract base class 2: public abstract class Shape { } 3:  4: // a basic rectangle 5: public class Rectangle : Shape 6: { 7: public int Widtgh { get; set; } 8: public int Height { get; set; } 9: } And let’s assume we have a sequence of Shape where every Shape is a Rectangle… 1: var shapes = new List<Shape> 2: { 3: new Rectangle { Width = 3, Height = 5 }, 4: new Rectangle { Width = 10, Height = 13 }, 5: // ... 6: }; To get the sequence of Shape as a sequence of Rectangle, of course, we could use a Select() clause, such as: 1: // select each Shape, cast it to Rectangle 2: var rectangles = shapes 3: .Select(s => (Rectangle)s) 4: .ToList(); But that’s a bit verbose, and fortunately there is already a facility built in and ready to use in the form of the Cast<TResult>() extension method: 1: // cast each item to Rectangle and store in a List<Rectangle> 2: var rectangles = shapes 3: .Cast<Rectangle>() 4: .ToList(); However, we should note that if anything in the list cannot be cast to a Rectangle, you will get an InvalidCastException thrown at runtime.  Thus, if our Shape sequence had a Circle in it, the call to Cast<Rectangle>() would have failed.  As such, you should only do this when you are reasonably sure of what the sequence actually contains (or are willing to handle an exception if you’re wrong). Another handy use of Cast<TResult>() is using it to convert an IEnumerable to an IEnumerable<T>.  If you look at the signature, you’ll see that the Cast<TResult>() extension method actually extends the older, object-based IEnumerable interface instead of the newer, generic IEnumerable<T>.  This is your gateway method for being able to use LINQ on older, non-generic sequences.  For example, consider the following: 1: // the older, non-generic collections are sequence of object 2: var shapes = new ArrayList 3: { 4: new Rectangle { Width = 3, Height = 13 }, 5: new Rectangle { Width = 10, Height = 20 }, 6: // ... 7: }; Since this is an older, object based collection, we cannot use the LINQ extension methods on it directly.  For example, if I wanted to query the Shape sequence for only those Rectangles whose Width is > 5, I can’t do this: 1: // compiler error, Where() operates on IEnumerable<T>, not IEnumerable 2: var bigRectangles = shapes.Where(r => r.Width > 5); However, I can use Cast<Rectangle>() to treat my ArrayList as an IEnumerable<Rectangle> and then do the query! 1: // ah, that’s better! 2: var bigRectangles = shapes.Cast<Rectangle>().Where(r => r.Width > 5); Or, if you prefer, in LINQ query expression syntax: 1: var bigRectangles = from s in shapes.Cast<Rectangle>() 2: where s.Width > 5 3: select s; One quick warning: Cast<TResult>() only attempts to cast, it won’t perform a cast conversion.  That is, consider this: 1: var intList = new List<int> { 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89 }; 2:  3: // casting ints to longs, this should work, right? 4: var asLong = intList.Cast<long>().ToList(); Will the code above work?  No, you’ll get a InvalidCastException. Remember that Cast<TResult>() is an extension of IEnumerable, thus it is a sequence of object, which means that it will box every int as an object as it enumerates over it, and there is no cast conversion from object to long, and thus the cast fails.  In other words, a cast from int to long will succeed because there is a conversion from int to long.  But a cast from int to object to long will not, because you can only unbox an item by casting it to its exact type. For more information on why cast-converting boxed values doesn’t work, see this post on The Dangers of Casting Boxed Values (here). OfType<TResult>() – Filter sequence to only items of type TResult So, we’ve seen how we can use Cast<TResult>() to change the type of our sequence, when we expect all the items of the sequence to be of a specific type.  But what do we do when a sequence contains many different types, and we are only concerned with a subset of a given type? For example, what if a sequence of Shape contains Rectangle and Circle instances, and we just want to select all of the Rectangle instances?  Well, let’s say we had this sequence of Shape: 1: var shapes = new List<Shape> 2: { 3: new Rectangle { Width = 3, Height = 5 }, 4: new Rectangle { Width = 10, Height = 13 }, 5: new Circle { Radius = 10 }, 6: new Square { Side = 13 }, 7: // ... 8: }; Well, we could get the rectangles using Select(), like: 1: var onlyRectangles = shapes.Where(s => s is Rectangle).ToList(); But fortunately, an easier way has already been written for us in the form of the OfType<T>() extension method: 1: // returns only a sequence of the shapes that are Rectangles 2: var onlyRectangles = shapes.OfType<Rectangle>().ToList(); Now we have a sequence of only the Rectangles in the original sequence, we can also use this to chain other queries that depend on Rectangles, such as: 1: // select only Rectangles, then filter to only those more than 2: // 5 units wide... 3: var onlyBigRectangles = shapes.OfType<Rectangle>() 4: .Where(r => r.Width > 5) 5: .ToList(); The OfType<Rectangle>() will filter the sequence to only the items that are of type Rectangle (or a subclass of it), and that results in an IEnumerable<Rectangle>, we can then apply the other LINQ extension methods to query that list further. Just as Cast<TResult>() is an extension method on IEnumerable (and not IEnumerable<T>), the same is true for OfType<T>().  This means that you can use OfType<TResult>() on object-based collections as well. For example, given an ArrayList containing Shapes, as below: 1: // object-based collections are a sequence of object 2: var shapes = new ArrayList 3: { 4: new Rectangle { Width = 3, Height = 5 }, 5: new Rectangle { Width = 10, Height = 13 }, 6: new Circle { Radius = 10 }, 7: new Square { Side = 13 }, 8: // ... 9: }; We can use OfType<Rectangle> to filter the sequence to only Rectangle items (and subclasses), and then chain other LINQ expressions, since we will then be of type IEnumerable<Rectangle>: 1: // OfType() converts the sequence of object to a new sequence 2: // containing only Rectangle or sub-types of Rectangle. 3: var onlyBigRectangles = shapes.OfType<Rectangle>() 4: .Where(r => r.Width > 5) 5: .ToList(); Summary So now we’ve seen two different ways to get a sequence of a superclass or interface down to a more specific sequence of a subclass or implementation.  The Cast<TResult>() method casts every item in the source sequence to type TResult, and the OfType<TResult>() method selects only those items in the source sequence that are of type TResult. You can use these to downcast sequences, or adapt older types and sequences that only implement IEnumerable (such as DataTable, ArrayList, etc.). Technorati Tags: C#,CSharp,.NET,LINQ,Little Wonders,TypeOf,Cast,IEnumerable<T>

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  • C#: Inheritance, Overriding, and Hiding

    - by Rosarch
    I'm having difficulty with an architectural decision for my C# XNA game. The basic entity in the world, such as a tree, zombie, or the player, is represented as a GameObject. Each GameObject is composed of at least a GameObjectController, GameObjectModel, and GameObjectView. These three are enough for simple entities, like inanimate trees or rocks. However, as I try to keep the functionality as factored out as possible, the inheritance begins to feel unwieldy. Syntactically, I'm not even sure how best to accomplish my goals. Here is the GameObjectController: public class GameObjectController { protected GameObjectModel model; protected GameObjectView view; public GameObjectController(GameObjectManager gameObjectManager) { this.gameObjectManager = gameObjectManager; model = new GameObjectModel(this); view = new GameObjectView(this); } public GameObjectManager GameObjectManager { get { return gameObjectManager; } } public virtual GameObjectView View { get { return view; } } public virtual GameObjectModel Model { get { return model; } } public virtual void Update(long tick) { } } I want to specify that each subclass of GameObjectController will have accessible at least a GameObjectView and GameObjectModel. If subclasses are fine using those classes, but perhaps are overriding for a more sophisticated Update() method, I don't want them to have to duplicate the code to produce those dependencies. So, the GameObjectController constructor sets those objects up. However, some objects do want to override the model and view. This is where the trouble comes in. Some objects need to fight, so they are CombatantGameObjects: public class CombatantGameObject : GameObjectController { protected new readonly CombatantGameModel model; public new virtual CombatantGameModel Model { get { return model; } } protected readonly CombatEngine combatEngine; public CombatantGameObject(GameObjectManager gameObjectManager, CombatEngine combatEngine) : base(gameObjectManager) { model = new CombatantGameModel(this); this.combatEngine = combatEngine; } public override void Update(long tick) { if (model.Health <= 0) { gameObjectManager.RemoveFromWorld(this); } base.Update(tick); } } Still pretty simple. Is my use of new to hide instance variables correct? Note that I'm assigning CombatantObjectController.model here, even though GameObjectController.Model was already set. And, combatants don't need any special view functionality, so they leave GameObjectController.View alone. Then I get down to the PlayerController, at which a bug is found. public class PlayerController : CombatantGameObject { private readonly IInputReader inputReader; private new readonly PlayerModel model; public new PlayerModel Model { get { return model; } } private float lastInventoryIndexAt; private float lastThrowAt; public PlayerController(GameObjectManager gameObjectManager, IInputReader inputReader, CombatEngine combatEngine) : base(gameObjectManager, combatEngine) { this.inputReader = inputReader; model = new PlayerModel(this); Model.Health = Constants.PLAYER_HEALTH; } public override void Update(long tick) { if (Model.Health <= 0) { gameObjectManager.RemoveFromWorld(this); for (int i = 0; i < 10; i++) { Debug.WriteLine("YOU DEAD SON!!!"); } return; } UpdateFromInput(tick); // .... } } The first time that this line is executed, I get a null reference exception: model.Body.ApplyImpulse(movementImpulse, model.Position); model.Position looks at model.Body, which is null. This is a function that initializes GameObjects before they are deployed into the world: public void Initialize(GameObjectController controller, IDictionary<string, string> data, WorldState worldState) { controller.View.read(data); controller.View.createSpriteAnimations(data, _assets); controller.Model.read(data); SetUpPhysics(controller, worldState, controller.Model.BoundingCircleRadius, Single.Parse(data["x"]), Single.Parse(data["y"]), bool.Parse(data["isBullet"])); } Every object is passed as a GameObjectController. Does that mean that if the object is really a PlayerController, controller.Model will refer to the base's GameObjectModel and not the PlayerController's overriden PlayerObjectModel? In response to rh: This means that now for a PlayerModel p, p.Model is not equivalent to ((CombatantGameObject)p).Model, and also not equivalent to ((GameObjectController)p).Model. That is exactly what I do not want. I want: PlayerController p; p.Model == ((CombatantGameObject)p).Model p.Model == ((GameObjectController)p).Model How can I do this? override?

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  • Dynamically register constructor methods in an AbstractFactory at compile time using C++ templates

    - by Horacio
    When implementing a MessageFactory class to instatiate Message objects I used something like: class MessageFactory { public: static Message *create(int type) { switch(type) { case PING_MSG: return new PingMessage(); case PONG_MSG: return new PongMessage(); .... } } This works ok but every time I add a new message I have to add a new XXX_MSG and modify the switch statement. After some research I found a way to dynamically update the MessageFactory at compile time so I can add as many messages as I want without need to modify the MessageFactory itself. This allows for cleaner and easier to maintain code as I do not need to modify three different places to add/remove message classes: #include <stdio.h> #include <stdlib.h> #include <string.h> #include <inttypes.h> class Message { protected: inline Message() {}; public: inline virtual ~Message() { } inline int getMessageType() const { return m_type; } virtual void say() = 0; protected: uint16_t m_type; }; template<int TYPE, typename IMPL> class MessageTmpl: public Message { enum { _MESSAGE_ID = TYPE }; public: static Message* Create() { return new IMPL(); } static const uint16_t MESSAGE_ID; // for registration protected: MessageTmpl() { m_type = MESSAGE_ID; } //use parameter to instanciate template }; typedef Message* (*t_pfFactory)(); class MessageFactory· { public: static uint16_t Register(uint16_t msgid, t_pfFactory factoryMethod) { printf("Registering constructor for msg id %d\n", msgid); m_List[msgid] = factoryMethod; return msgid; } static Message *Create(uint16_t msgid) { return m_List[msgid](); } static t_pfFactory m_List[65536]; }; template <int TYPE, typename IMPL> const uint16_t MessageTmpl<TYPE, IMPL >::MESSAGE_ID = MessageFactory::Register( MessageTmpl<TYPE, IMPL >::_MESSAGE_ID, &MessageTmpl<TYPE, IMPL >::Create); class PingMessage: public MessageTmpl < 10, PingMessage > {· public: PingMessage() {} virtual void say() { printf("Ping\n"); } }; class PongMessage: public MessageTmpl < 11, PongMessage > {· public: PongMessage() {} virtual void say() { printf("Pong\n"); } }; t_pfFactory MessageFactory::m_List[65536]; int main(int argc, char **argv) { Message *msg1; Message *msg2; msg1 = MessageFactory::Create(10); msg1->say(); msg2 = MessageFactory::Create(11); msg2->say(); delete msg1; delete msg2; return 0; } The template here does the magic by registering into the MessageFactory class, all new Message classes (e.g. PingMessage and PongMessage) that subclass from MessageTmpl. This works great and simplifies code maintenance but I still have some questions about this technique: Is this a known technique/pattern? what is the name? I want to search more info about it. I want to make the array for storing new constructors MessageFactory::m_List[65536] a std::map but doing so causes the program to segfault even before reaching main(). Creating an array of 65536 elements is overkill but I have not found a way to make this a dynamic container. For all message classes that are subclasses of MessageTmpl I have to implement the constructor. If not it won't register in the MessageFactory. For example commenting the constructor of the PongMessage: class PongMessage: public MessageTmpl < 11, PongMessage > { public: //PongMessage() {} /* HERE */ virtual void say() { printf("Pong\n"); } }; would result in the PongMessage class not being registered by the MessageFactory and the program would segfault in the MessageFactory::Create(11) line. The question is why the class won't register? Having to add the empty implementation of the 100+ messages I need feels inefficient and unnecessary.

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  • Developing Spring Portlet for use inside Weblogic Portal / Webcenter Portal

    - by Murali Veligeti
    We need to understand the main difference between portlet workflow and servlet workflow.The main difference between portlet workflow and servlet workflow is that, the request to the portlet can have two distinct phases: 1) Action phase 2) Render phase. The Action phase is executed only once and is where any 'backend' changes or actions occur, such as making changes in a database. The Render phase then produces what is displayed to the user each time the display is refreshed. The critical point here is that for a single overall request, the action phase is executed only once, but the render phase may be executed multiple times. This provides a clean separation between the activities that modify the persistent state of your system and the activities that generate what is displayed to the user.The dual phases of portlet requests are one of the real strengths of the JSR-168 specification. For example, dynamic search results can be updated routinely on the display without the user explicitly re-running the search. Most other portlet MVC frameworks attempt to completely hide the two phases from the developer and make it look as much like traditional servlet development as possible - we think this approach removes one of the main benefits of using portlets. So, the separation of the two phases is preserved throughout the Spring Portlet MVC framework. The primary manifestation of this approach is that where the servlet version of the MVC classes will have one method that deals with the request, the portlet version of the MVC classes will have two methods that deal with the request: one for the action phase and one for the render phase. For example, where the servlet version of AbstractController has the handleRequestInternal(..) method, the portlet version of AbstractController has handleActionRequestInternal(..) and handleRenderRequestInternal(..) methods.The Spring Portlet Framework is designed around a DispatcherPortlet that dispatches requests to handlers, with configurable handler mappings and view resolution, just as the DispatcherServlet in the Spring Web Framework does.  Developing portlet.xml Let's start the sample development by creating the portlet.xml file in the /WebContent/WEB-INF/ folder as shown below: <?xml version="1.0" encoding="UTF-8"?> <portlet-app version="2.0" xmlns="http://java.sun.com/xml/ns/portlet/portlet-app_2_0.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <portlet> <portlet-name>SpringPortletName</portlet-name> <portlet-class>org.springframework.web.portlet.DispatcherPortlet</portlet-class> <supports> <mime-type>text/html</mime-type> <portlet-mode>view</portlet-mode> </supports> <portlet-info> <title>SpringPortlet</title> </portlet-info> </portlet> </portlet-app> DispatcherPortlet is responsible for handling every client request. When it receives a request, it finds out which Controller class should be used for handling this request, and then it calls its handleActionRequest() or handleRenderRequest() method based on the request processing phase. The Controller class executes business logic and returns a View name that should be used for rendering markup to the user. The DispatcherPortlet then forwards control to that View for actual markup generation. As you can see, DispatcherPortlet is the central dispatcher for use within Spring Portlet MVC Framework. Note that your portlet application can define more than one DispatcherPortlet. If it does so, then each of these portlets operates its own namespace, loading its application context and handler mapping. The DispatcherPortlet is also responsible for loading application context (Spring configuration file) for this portlet. First, it tries to check the value of the configLocation portlet initialization parameter. If that parameter is not specified, it takes the portlet name (that is, the value of the <portlet-name> element), appends "-portlet.xml" to it, and tries to load that file from the /WEB-INF folder. In the portlet.xml file, we did not specify the configLocation initialization parameter, so let's create SpringPortletName-portlet.xml file in the next section. Developing SpringPortletName-portlet.xml Create the SpringPortletName-portlet.xml file in the /WebContent/WEB-INF folder of your application as shown below: <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd"> <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/> <property name="prefix" value="/jsp/"/> <property name="suffix" value=".jsp"/> </bean> <bean id="pointManager" class="com.wlp.spring.bo.internal.PointManagerImpl"> <property name="users"> <list> <ref bean="point1"/> <ref bean="point2"/> <ref bean="point3"/> <ref bean="point4"/> </list> </property> </bean> <bean id="point1" class="com.wlp.spring.bean.User"> <property name="name" value="Murali"/> <property name="points" value="6"/> </bean> <bean id="point2" class="com.wlp.spring.bean.User"> <property name="name" value="Sai"/> <property name="points" value="13"/> </bean> <bean id="point3" class="com.wlp.spring.bean.User"> <property name="name" value="Rama"/> <property name="points" value="43"/> </bean> <bean id="point4" class="com.wlp.spring.bean.User"> <property name="name" value="Krishna"/> <property name="points" value="23"/> </bean> <bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource"> <property name="basename" value="messages"/> </bean> <bean name="/users.htm" id="userController" class="com.wlp.spring.controller.UserController"> <property name="pointManager" ref="pointManager"/> </bean> <bean name="/pointincrease.htm" id="pointIncreaseController" class="com.wlp.spring.controller.IncreasePointsFormController"> <property name="sessionForm" value="true"/> <property name="pointManager" ref="pointManager"/> <property name="commandName" value="pointIncrease"/> <property name="commandClass" value="com.wlp.spring.bean.PointIncrease"/> <property name="formView" value="pointincrease"/> <property name="successView" value="users"/> </bean> <bean id="parameterMappingInterceptor" class="org.springframework.web.portlet.handler.ParameterMappingInterceptor" /> <bean id="portletModeParameterHandlerMapping" class="org.springframework.web.portlet.handler.PortletModeParameterHandlerMapping"> <property name="order" value="1" /> <property name="interceptors"> <list> <ref bean="parameterMappingInterceptor" /> </list> </property> <property name="portletModeParameterMap"> <map> <entry key="view"> <map> <entry key="pointincrease"> <ref bean="pointIncreaseController" /> </entry> <entry key="users"> <ref bean="userController" /> </entry> </map> </entry> </map> </property> </bean> <bean id="portletModeHandlerMapping" class="org.springframework.web.portlet.handler.PortletModeHandlerMapping"> <property name="order" value="2" /> <property name="portletModeMap"> <map> <entry key="view"> <ref bean="userController" /> </entry> </map> </property> </bean> </beans> The SpringPortletName-portlet.xml file is an application context file for your MVC portlet. It has a couple of bean definitions: viewController. At this point, remember that the viewController bean definition points to the com.ibm.developerworks.springmvc.ViewController.java class. portletModeHandlerMapping. As we discussed in the last section, whenever DispatcherPortlet gets a client request, it tries to find a suitable Controller class for handling that request. That is where PortletModeHandlerMapping comes into the picture. The PortletModeHandlerMapping class is a simple implementation of the HandlerMapping interface and is used by DispatcherPortlet to find a suitable Controller for every request. The PortletModeHandlerMapping class uses Portlet mode for the current request to find a suitable Controller class to use for handling the request. The portletModeMap property of portletModeHandlerMapping bean is the place where we map the Portlet mode name against the Controller class. In the sample code, we show that viewController is responsible for handling View mode requests. Developing UserController.java In the preceding section, you learned that the viewController bean is responsible for handling all the View mode requests. Your next step is to create the UserController.java class as shown below: public class UserController extends AbstractController { private PointManager pointManager; public void handleActionRequest(ActionRequest request, ActionResponse response) throws Exception { } public ModelAndView handleRenderRequest(RenderRequest request, RenderResponse response) throws ServletException, IOException { String now = (new java.util.Date()).toString(); Map<String, Object> myModel = new HashMap<String, Object>(); myModel.put("now", now); myModel.put("users", this.pointManager.getUsers()); return new ModelAndView("users", "model", myModel); } public void setPointManager(PointManager pointManager) { this.pointManager = pointManager; } } Every controller class in Spring Portlet MVC Framework must implement the org.springframework.web. portlet.mvc.Controller interface directly or indirectly. To make things easier, Spring Framework provides AbstractController class, which is the default implementation of the Controller interface. As a developer, you should always extend your controller from either AbstractController or one of its more specific subclasses. Any implementation of the Controller class should be reusable, thread-safe, and capable of handling multiple requests throughout the lifecycle of the portlet. In the sample code, we create the ViewController class by extending it from AbstractController. Because we don't want to do any action processing in the HelloSpringPortletMVC portlet, we override only the handleRenderRequest() method of AbstractController. Now, the only thing that HelloWorldPortletMVC should do is render the markup of View.jsp to the user when it receives a user request to do so. To do that, return the object of ModelAndView with a value of view equal to View. Developing web.xml According to Portlet Specification 1.0, every portlet application is also a Servlet Specification 2.3-compliant Web application, and it needs a Web application deployment descriptor (that is, web.xml). Let’s create the web.xml file in the /WEB-INF/ folder as shown in listing 4. Follow these steps: Open the existing web.xml file located at /WebContent/WEB-INF/web.xml. Replace the contents of this file with the code as shown below: <servlet> <servlet-name>ViewRendererServlet</servlet-name> <servlet-class>org.springframework.web.servlet.ViewRendererServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>ViewRendererServlet</servlet-name> <url-pattern>/WEB-INF/servlet/view</url-pattern> </servlet-mapping> <context-param> <param-name>contextConfigLocation</param-name> <param-value>/WEB-INF/applicationContext.xml</param-value> </context-param> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> The web.xml file for the sample portlet declares two things: ViewRendererServlet. The ViewRendererServlet is the bridge servlet for portlet support. During the render phase, DispatcherPortlet wraps PortletRequest into ServletRequest and forwards control to ViewRendererServlet for actual rendering. This process allows Spring Portlet MVC Framework to use the same View infrastructure as that of its servlet version, that is, Spring Web MVC Framework. ContextLoaderListener. The ContextLoaderListener class takes care of loading Web application context at the time of the Web application startup. The Web application context is shared by all the portlets in the portlet application. In case of duplicate bean definition, the bean definition in the portlet application context takes precedence over the Web application context. The ContextLoader class tries to read the value of the contextConfigLocation Web context parameter to find out the location of the context file. If the contextConfigLocation parameter is not set, then it uses the default value, which is /WEB-INF/applicationContext.xml, to load the context file. The Portlet Controller interface requires two methods that handle the two phases of a portlet request: the action request and the render request. The action phase should be capable of handling an action request and the render phase should be capable of handling a render request and returning an appropriate model and view. While the Controller interface is quite abstract, Spring Portlet MVC offers a lot of controllers that already contain a lot of the functionality you might need – most of these are very similar to controllers from Spring Web MVC. The Controller interface just defines the most common functionality required of every controller - handling an action request, handling a render request, and returning a model and a view. How rendering works As you know, when the user tries to access a page with PointSystemPortletMVC portlet on it or when the user performs some action on any other portlet on that page or tries to refresh that page, a render request is sent to the PointSystemPortletMVC portlet. In the sample code, because DispatcherPortlet is the main portlet class, Weblogic Portal / Webcenter Portal calls its render() method and then the following sequence of events occurs: The render() method of DispatcherPortlet calls the doDispatch() method, which in turn calls the doRender() method. After the doRenderService() method gets control, first it tries to find out the locale of the request by calling the PortletRequest.getLocale() method. This locale is used while making all the locale-related decisions for choices such as which resource bundle should be loaded or which JSP should be displayed to the user based on the locale. After that, the doRenderService() method starts iterating through all the HandlerMapping classes configured for this portlet, calling their getHandler() method to identify the appropriate Controller for handling this request. In the sample code, we have configured only PortletModeHandlerMapping as a HandlerMapping class. The PortletModeHandlerMapping class reads the value of the current portlet mode, and based on that, it finds out, the Controller class that should be used to handle this request. In the sample code, ViewController is configured to handle the View mode request so that the PortletModeHandlerMapping class returns the object of ViewController. After the object of ViewController is returned, the doRenderService() method calls its handleRenderRequestInternal() method. Implementation of the handleRenderRequestInternal() method in ViewController.java is very simple. It logs a message saying that it got control, and then it creates an instance of ModelAndView with a value equal to View and returns it to DispatcherPortlet. After control returns to doRenderService(), the next task is to figure out how to render View. For that, DispatcherPortlet starts iterating through all the ViewResolvers configured in your portlet application, calling their resolveViewName() method. In the sample code we have configured only one ViewResolver, InternalResourceViewResolver. When its resolveViewName() method is called with viewName, it tries to add /WEB-INF/jsp as a prefix to the view name and to add JSP as a suffix. And it checks if /WEB-INF/jsp/View.jsp exists. If it does exist, it returns the object of JstlView wrapping View.jsp. After control is returned to the doRenderService() method, it creates the object PortletRequestDispatcher, which points to /WEB-INF/servlet/view – that is, ViewRendererServlet. Then it sets the object of JstlView in the request and dispatches the request to ViewRendererServlet. After ViewRendererServlet gets control, it reads the JstlView object from the request attribute and creates another RequestDispatcher pointing to the /WEB-INF/jsp/View.jsp URL and passes control to it for actual markup generation. The markup generated by View.jsp is returned to user. At this point, you may question the need for ViewRendererServlet. Why can't DispatcherPortlet directly forward control to View.jsp? Adding ViewRendererServlet in between allows Spring Portlet MVC Framework to reuse the existing View infrastructure. You may appreciate this more when we discuss how easy it is to integrate Apache Tiles Framework with your Spring Portlet MVC Framework. The attached project SpringPortlet.zip should be used to import the project in to your OEPE Workspace. SpringPortlet_Jars.zip contains jar files required for the application. Project is written on Spring 2.5.  The same JSR 168 portlet should work on Webcenter Portal as well.  Downloads: Download WeblogicPotal Project which consists of Spring Portlet. Download Spring Jars In-addition to above you need to download Spring.jar (Spring2.5)

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  • Connection drop problem with Hibernate-mysql-c3p0

    - by user344788
    hi all, This is an issue which I have seen all across the web. I will bring it up again as till now I don't have a fix for the same. I am using hibernate 3. mysql 5 and latest c3p0 jar. I am getting a broken pipe exception. Following is my hibernate.cfg file. com.mysql.jdbc.Driver org.hibernate.dialect.MySQLDialect <property name="hibernate.show_sql">true</property> <property name="hibernate.use_sql_comments">true</property> <property name="hibernate.current_session_context_class">thread</property> <property name="connection.autoReconnect">true</property> <property name="connection.autoReconnectForPools">true</property> <property name="connection.is-connection-validation-required">true</property> <!--<property name="c3p0.min_size">5</property> <property name="c3p0.max_size">20</property> <property name="c3p0.timeout">1800</property> <property name="c3p0.max_statements">50</property> --><property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider </property> <property name="hibernate.c3p0.acquireRetryAttempts">30</property> <property name="hibernate.c3p0.acquireIncrement">5</property> <property name="hibernate.c3p0.automaticTestTable">C3P0TestTable</property> <property name="hibernate.c3p0.idleConnectionTestPeriod">36000</property> <property name="hibernate.c3p0.initialPoolSize">20</property> <property name="hibernate.c3p0.maxPoolSize">100</property> <property name="hibernate.c3p0.maxIdleTime">1200</property> <property name="hibernate.c3p0.maxStatements">50</property> <property name="hibernate.c3p0.minPoolSize">10</property>--> My connection pooling is occurring fine. During the day it is fine , but once i keep it idle over the night ,next day I find it giving me broken connection error. public class HibernateUtil { private static Logger log = Logger.getLogger(HibernateUtil.class); //private static Log log = LogFactory.getLog(HibernateUtil.class); private static Configuration configuration; private static SessionFactory sessionFactory; static { // Create the initial SessionFactory from the default configuration files try { log.debug("Initializing Hibernate"); // Read hibernate.properties, if present configuration = new Configuration(); // Use annotations: configuration = new AnnotationConfiguration(); // Read hibernate.cfg.xml (has to be present) configuration.configure(); // Build and store (either in JNDI or static variable) rebuildSessionFactory(configuration); log.debug("Hibernate initialized, call HibernateUtil.getSessionFactory()"); } catch (Throwable ex) { // We have to catch Throwable, otherwise we will miss // NoClassDefFoundError and other subclasses of Error log.error("Building SessionFactory failed.", ex); throw new ExceptionInInitializerError(ex); } } /** * Returns the Hibernate configuration that was used to build the SessionFactory. * * @return Configuration */ public static Configuration getConfiguration() { return configuration; } /** * Returns the global SessionFactory either from a static variable or a JNDI lookup. * * @return SessionFactory */ public static SessionFactory getSessionFactory() { String sfName = configuration.getProperty(Environment.SESSION_FACTORY_NAME); System.out.println("Current s name is "+sfName); if ( sfName != null) { System.out.println("Looking up SessionFactory in JNDI"); log.debug("Looking up SessionFactory in JNDI"); try { System.out.println("Returning new sssion factory"); return (SessionFactory) new InitialContext().lookup(sfName); } catch (NamingException ex) { throw new RuntimeException(ex); } } else if (sessionFactory == null) { System.out.println("calling rebuild session factory now"); rebuildSessionFactory(); } return sessionFactory; } /** * Closes the current SessionFactory and releases all resources. * <p> * The only other method that can be called on HibernateUtil * after this one is rebuildSessionFactory(Configuration). */ public static void shutdown() { log.debug("Shutting down Hibernate"); // Close caches and connection pools getSessionFactory().close(); // Clear static variables sessionFactory = null; } /** * Rebuild the SessionFactory with the static Configuration. * <p> * Note that this method should only be used with static SessionFactory * management, not with JNDI or any other external registry. This method also closes * the old static variable SessionFactory before, if it is still open. */ public static void rebuildSessionFactory() { log.debug("Using current Configuration to rebuild SessionFactory"); rebuildSessionFactory(configuration); } /** * Rebuild the SessionFactory with the given Hibernate Configuration. * <p> * HibernateUtil does not configure() the given Configuration object, * it directly calls buildSessionFactory(). This method also closes * the old static variable SessionFactory before, if it is still open. * * @param cfg */ public static void rebuildSessionFactory(Configuration cfg) { log.debug("Rebuilding the SessionFactory from given Configuration"); if (sessionFactory != null && !sessionFactory.isClosed()) sessionFactory.close(); if (cfg.getProperty(Environment.SESSION_FACTORY_NAME) != null) { log.debug("Managing SessionFactory in JNDI"); cfg.buildSessionFactory(); } else { log.debug("Holding SessionFactory in static variable"); sessionFactory = cfg.buildSessionFactory(); } configuration = cfg; } } Above is my code for the session factory. And I have only select operations . And below is the method which is used most often to execute my select queries. One tricky thing which I am not understanding is in my findById method i am using this line of code getSession().beginTransaction(); without which it gives me an error saying that this cannot happpen without a transaction. But nowhere I am closing this transaction. And thers no method to close a transaction apart from commit or rollback (as far as i know) which are not applicable for select statements. public T findById(ID id, boolean lock) throws HibernateException, DAOException { log.debug("findNyId invoked with ID ="+id+"and lock ="+lock); T entity; getSession().beginTransaction(); if (lock) entity = (T) getSession().load(getPersistentClass(), id, LockMode.UPGRADE); else entity = (T) getSession().load(getPersistentClass(), id); return entity; } Can anyone please suggest what can I do ? I have tried out almost every solution available via googling, on stackoverlow or on hibernate forums with no avail. (And increasing wait_timeout on mysql is not a valid option in my case).

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  • value types in the vm

    - by john.rose
    value types in the vm p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} p.p2 {margin: 0.0px 0.0px 14.0px 0.0px; font: 14.0px Times} p.p3 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times} p.p4 {margin: 0.0px 0.0px 15.0px 0.0px; font: 14.0px Times} p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier} p.p6 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier; min-height: 17.0px} p.p7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p8 {margin: 0.0px 0.0px 0.0px 36.0px; text-indent: -36.0px; font: 14.0px Times; min-height: 18.0px} p.p9 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p10 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; color: #000000} li.li1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} li.li7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} span.s1 {font: 14.0px Courier} span.s2 {color: #000000} span.s3 {font: 14.0px Courier; color: #000000} ol.ol1 {list-style-type: decimal} Or, enduring values for a changing world. Introduction A value type is a data type which, generally speaking, is designed for being passed by value in and out of methods, and stored by value in data structures. The only value types which the Java language directly supports are the eight primitive types. Java indirectly and approximately supports value types, if they are implemented in terms of classes. For example, both Integer and String may be viewed as value types, especially if their usage is restricted to avoid operations appropriate to Object. In this note, we propose a definition of value types in terms of a design pattern for Java classes, accompanied by a set of usage restrictions. We also sketch the relation of such value types to tuple types (which are a JVM-level notion), and point out JVM optimizations that can apply to value types. This note is a thought experiment to extend the JVM’s performance model in support of value types. The demonstration has two phases.  Initially the extension can simply use design patterns, within the current bytecode architecture, and in today’s Java language. But if the performance model is to be realized in practice, it will probably require new JVM bytecode features, changes to the Java language, or both.  We will look at a few possibilities for these new features. An Axiom of Value In the context of the JVM, a value type is a data type equipped with construction, assignment, and equality operations, and a set of typed components, such that, whenever two variables of the value type produce equal corresponding values for their components, the values of the two variables cannot be distinguished by any JVM operation. Here are some corollaries: A value type is immutable, since otherwise a copy could be constructed and the original could be modified in one of its components, allowing the copies to be distinguished. Changing the component of a value type requires construction of a new value. The equals and hashCode operations are strictly component-wise. If a value type is represented by a JVM reference, that reference cannot be successfully synchronized on, and cannot be usefully compared for reference equality. A value type can be viewed in terms of what it doesn’t do. We can say that a value type omits all value-unsafe operations, which could violate the constraints on value types.  These operations, which are ordinarily allowed for Java object types, are pointer equality comparison (the acmp instruction), synchronization (the monitor instructions), all the wait and notify methods of class Object, and non-trivial finalize methods. The clone method is also value-unsafe, although for value types it could be treated as the identity function. Finally, and most importantly, any side effect on an object (however visible) also counts as an value-unsafe operation. A value type may have methods, but such methods must not change the components of the value. It is reasonable and useful to define methods like toString, equals, and hashCode on value types, and also methods which are specifically valuable to users of the value type. Representations of Value Value types have two natural representations in the JVM, unboxed and boxed. An unboxed value consists of the components, as simple variables. For example, the complex number x=(1+2i), in rectangular coordinate form, may be represented in unboxed form by the following pair of variables: /*Complex x = Complex.valueOf(1.0, 2.0):*/ double x_re = 1.0, x_im = 2.0; These variables might be locals, parameters, or fields. Their association as components of a single value is not defined to the JVM. Here is a sample computation which computes the norm of the difference between two complex numbers: double distance(/*Complex x:*/ double x_re, double x_im,         /*Complex y:*/ double y_re, double y_im) {     /*Complex z = x.minus(y):*/     double z_re = x_re - y_re, z_im = x_im - y_im;     /*return z.abs():*/     return Math.sqrt(z_re*z_re + z_im*z_im); } A boxed representation groups component values under a single object reference. The reference is to a ‘wrapper class’ that carries the component values in its fields. (A primitive type can naturally be equated with a trivial value type with just one component of that type. In that view, the wrapper class Integer can serve as a boxed representation of value type int.) The unboxed representation of complex numbers is practical for many uses, but it fails to cover several major use cases: return values, array elements, and generic APIs. The two components of a complex number cannot be directly returned from a Java function, since Java does not support multiple return values. The same story applies to array elements: Java has no ’array of structs’ feature. (Double-length arrays are a possible workaround for complex numbers, but not for value types with heterogeneous components.) By generic APIs I mean both those which use generic types, like Arrays.asList and those which have special case support for primitive types, like String.valueOf and PrintStream.println. Those APIs do not support unboxed values, and offer some problems to boxed values. Any ’real’ JVM type should have a story for returns, arrays, and API interoperability. The basic problem here is that value types fall between primitive types and object types. Value types are clearly more complex than primitive types, and object types are slightly too complicated. Objects are a little bit dangerous to use as value carriers, since object references can be compared for pointer equality, and can be synchronized on. Also, as many Java programmers have observed, there is often a performance cost to using wrapper objects, even on modern JVMs. Even so, wrapper classes are a good starting point for talking about value types. If there were a set of structural rules and restrictions which would prevent value-unsafe operations on value types, wrapper classes would provide a good notation for defining value types. This note attempts to define such rules and restrictions. Let’s Start Coding Now it is time to look at some real code. Here is a definition, written in Java, of a complex number value type. @ValueSafe public final class Complex implements java.io.Serializable {     // immutable component structure:     public final double re, im;     private Complex(double re, double im) {         this.re = re; this.im = im;     }     // interoperability methods:     public String toString() { return "Complex("+re+","+im+")"; }     public List<Double> asList() { return Arrays.asList(re, im); }     public boolean equals(Complex c) {         return re == c.re && im == c.im;     }     public boolean equals(@ValueSafe Object x) {         return x instanceof Complex && equals((Complex) x);     }     public int hashCode() {         return 31*Double.valueOf(re).hashCode()                 + Double.valueOf(im).hashCode();     }     // factory methods:     public static Complex valueOf(double re, double im) {         return new Complex(re, im);     }     public Complex changeRe(double re2) { return valueOf(re2, im); }     public Complex changeIm(double im2) { return valueOf(re, im2); }     public static Complex cast(@ValueSafe Object x) {         return x == null ? ZERO : (Complex) x;     }     // utility methods and constants:     public Complex plus(Complex c)  { return new Complex(re+c.re, im+c.im); }     public Complex minus(Complex c) { return new Complex(re-c.re, im-c.im); }     public double abs() { return Math.sqrt(re*re + im*im); }     public static final Complex PI = valueOf(Math.PI, 0.0);     public static final Complex ZERO = valueOf(0.0, 0.0); } This is not a minimal definition, because it includes some utility methods and other optional parts.  The essential elements are as follows: The class is marked as a value type with an annotation. The class is final, because it does not make sense to create subclasses of value types. The fields of the class are all non-private and final.  (I.e., the type is immutable and structurally transparent.) From the supertype Object, all public non-final methods are overridden. The constructor is private. Beyond these bare essentials, we can observe the following features in this example, which are likely to be typical of all value types: One or more factory methods are responsible for value creation, including a component-wise valueOf method. There are utility methods for complex arithmetic and instance creation, such as plus and changeIm. There are static utility constants, such as PI. The type is serializable, using the default mechanisms. There are methods for converting to and from dynamically typed references, such as asList and cast. The Rules In order to use value types properly, the programmer must avoid value-unsafe operations.  A helpful Java compiler should issue errors (or at least warnings) for code which provably applies value-unsafe operations, and should issue warnings for code which might be correct but does not provably avoid value-unsafe operations.  No such compilers exist today, but to simplify our account here, we will pretend that they do exist. A value-safe type is any class, interface, or type parameter marked with the @ValueSafe annotation, or any subtype of a value-safe type.  If a value-safe class is marked final, it is in fact a value type.  All other value-safe classes must be abstract.  The non-static fields of a value class must be non-public and final, and all its constructors must be private. Under the above rules, a standard interface could be helpful to define value types like Complex.  Here is an example: @ValueSafe public interface ValueType extends java.io.Serializable {     // All methods listed here must get redefined.     // Definitions must be value-safe, which means     // they may depend on component values only.     List<? extends Object> asList();     int hashCode();     boolean equals(@ValueSafe Object c);     String toString(); } //@ValueSafe inherited from supertype: public final class Complex implements ValueType { … The main advantage of such a conventional interface is that (unlike an annotation) it is reified in the runtime type system.  It could appear as an element type or parameter bound, for facilities which are designed to work on value types only.  More broadly, it might assist the JVM to perform dynamic enforcement of the rules for value types. Besides types, the annotation @ValueSafe can mark fields, parameters, local variables, and methods.  (This is redundant when the type is also value-safe, but may be useful when the type is Object or another supertype of a value type.)  Working forward from these annotations, an expression E is defined as value-safe if it satisfies one or more of the following: The type of E is a value-safe type. E names a field, parameter, or local variable whose declaration is marked @ValueSafe. E is a call to a method whose declaration is marked @ValueSafe. E is an assignment to a value-safe variable, field reference, or array reference. E is a cast to a value-safe type from a value-safe expression. E is a conditional expression E0 ? E1 : E2, and both E1 and E2 are value-safe. Assignments to value-safe expressions and initializations of value-safe names must take their values from value-safe expressions. A value-safe expression may not be the subject of a value-unsafe operation.  In particular, it cannot be synchronized on, nor can it be compared with the “==” operator, not even with a null or with another value-safe type. In a program where all of these rules are followed, no value-type value will be subject to a value-unsafe operation.  Thus, the prime axiom of value types will be satisfied, that no two value type will be distinguishable as long as their component values are equal. More Code To illustrate these rules, here are some usage examples for Complex: Complex pi = Complex.valueOf(Math.PI, 0); Complex zero = pi.changeRe(0);  //zero = pi; zero.re = 0; ValueType vtype = pi; @SuppressWarnings("value-unsafe")   Object obj = pi; @ValueSafe Object obj2 = pi; obj2 = new Object();  // ok List<Complex> clist = new ArrayList<Complex>(); clist.add(pi);  // (ok assuming List.add param is @ValueSafe) List<ValueType> vlist = new ArrayList<ValueType>(); vlist.add(pi);  // (ok) List<Object> olist = new ArrayList<Object>(); olist.add(pi);  // warning: "value-unsafe" boolean z = pi.equals(zero); boolean z1 = (pi == zero);  // error: reference comparison on value type boolean z2 = (pi == null);  // error: reference comparison on value type boolean z3 = (pi == obj2);  // error: reference comparison on value type synchronized (pi) { }  // error: synch of value, unpredictable result synchronized (obj2) { }  // unpredictable result Complex qq = pi; qq = null;  // possible NPE; warning: “null-unsafe" qq = (Complex) obj;  // warning: “null-unsafe" qq = Complex.cast(obj);  // OK @SuppressWarnings("null-unsafe")   Complex empty = null;  // possible NPE qq = empty;  // possible NPE (null pollution) The Payoffs It follows from this that either the JVM or the java compiler can replace boxed value-type values with unboxed ones, without affecting normal computations.  Fields and variables of value types can be split into their unboxed components.  Non-static methods on value types can be transformed into static methods which take the components as value parameters. Some common questions arise around this point in any discussion of value types. Why burden the programmer with all these extra rules?  Why not detect programs automagically and perform unboxing transparently?  The answer is that it is easy to break the rules accidently unless they are agreed to by the programmer and enforced.  Automatic unboxing optimizations are tantalizing but (so far) unreachable ideal.  In the current state of the art, it is possible exhibit benchmarks in which automatic unboxing provides the desired effects, but it is not possible to provide a JVM with a performance model that assures the programmer when unboxing will occur.  This is why I’m writing this note, to enlist help from, and provide assurances to, the programmer.  Basically, I’m shooting for a good set of user-supplied “pragmas” to frame the desired optimization. Again, the important thing is that the unboxing must be done reliably, or else programmers will have no reason to work with the extra complexity of the value-safety rules.  There must be a reasonably stable performance model, wherein using a value type has approximately the same performance characteristics as writing the unboxed components as separate Java variables. There are some rough corners to the present scheme.  Since Java fields and array elements are initialized to null, value-type computations which incorporate uninitialized variables can produce null pointer exceptions.  One workaround for this is to require such variables to be null-tested, and the result replaced with a suitable all-zero value of the value type.  That is what the “cast” method does above. Generically typed APIs like List<T> will continue to manipulate boxed values always, at least until we figure out how to do reification of generic type instances.  Use of such APIs will elicit warnings until their type parameters (and/or relevant members) are annotated or typed as value-safe.  Retrofitting List<T> is likely to expose flaws in the present scheme, which we will need to engineer around.  Here are a couple of first approaches: public interface java.util.List<@ValueSafe T> extends Collection<T> { … public interface java.util.List<T extends Object|ValueType> extends Collection<T> { … (The second approach would require disjunctive types, in which value-safety is “contagious” from the constituent types.) With more transformations, the return value types of methods can also be unboxed.  This may require significant bytecode-level transformations, and would work best in the presence of a bytecode representation for multiple value groups, which I have proposed elsewhere under the title “Tuples in the VM”. But for starters, the JVM can apply this transformation under the covers, to internally compiled methods.  This would give a way to express multiple return values and structured return values, which is a significant pain-point for Java programmers, especially those who work with low-level structure types favored by modern vector and graphics processors.  The lack of multiple return values has a strong distorting effect on many Java APIs. Even if the JVM fails to unbox a value, there is still potential benefit to the value type.  Clustered computing systems something have copy operations (serialization or something similar) which apply implicitly to command operands.  When copying JVM objects, it is extremely helpful to know when an object’s identity is important or not.  If an object reference is a copied operand, the system may have to create a proxy handle which points back to the original object, so that side effects are visible.  Proxies must be managed carefully, and this can be expensive.  On the other hand, value types are exactly those types which a JVM can “copy and forget” with no downside. Array types are crucial to bulk data interfaces.  (As data sizes and rates increase, bulk data becomes more important than scalar data, so arrays are definitely accompanying us into the future of computing.)  Value types are very helpful for adding structure to bulk data, so a successful value type mechanism will make it easier for us to express richer forms of bulk data. Unboxing arrays (i.e., arrays containing unboxed values) will provide better cache and memory density, and more direct data movement within clustered or heterogeneous computing systems.  They require the deepest transformations, relative to today’s JVM.  There is an impedance mismatch between value-type arrays and Java’s covariant array typing, so compromises will need to be struck with existing Java semantics.  It is probably worth the effort, since arrays of unboxed value types are inherently more memory-efficient than standard Java arrays, which rely on dependent pointer chains. It may be sufficient to extend the “value-safe” concept to array declarations, and allow low-level transformations to change value-safe array declarations from the standard boxed form into an unboxed tuple-based form.  Such value-safe arrays would not be convertible to Object[] arrays.  Certain connection points, such as Arrays.copyOf and System.arraycopy might need additional input/output combinations, to allow smooth conversion between arrays with boxed and unboxed elements. Alternatively, the correct solution may have to wait until we have enough reification of generic types, and enough operator overloading, to enable an overhaul of Java arrays. Implicit Method Definitions The example of class Complex above may be unattractively complex.  I believe most or all of the elements of the example class are required by the logic of value types. If this is true, a programmer who writes a value type will have to write lots of error-prone boilerplate code.  On the other hand, I think nearly all of the code (except for the domain-specific parts like plus and minus) can be implicitly generated. Java has a rule for implicitly defining a class’s constructor, if no it defines no constructors explicitly.  Likewise, there are rules for providing default access modifiers for interface members.  Because of the highly regular structure of value types, it might be reasonable to perform similar implicit transformations on value types.  Here’s an example of a “highly implicit” definition of a complex number type: public class Complex implements ValueType {  // implicitly final     public double re, im;  // implicitly public final     //implicit methods are defined elementwise from te fields:     //  toString, asList, equals(2), hashCode, valueOf, cast     //optionally, explicit methods (plus, abs, etc.) would go here } In other words, with the right defaults, a simple value type definition can be a one-liner.  The observant reader will have noticed the similarities (and suitable differences) between the explicit methods above and the corresponding methods for List<T>. Another way to abbreviate such a class would be to make an annotation the primary trigger of the functionality, and to add the interface(s) implicitly: public @ValueType class Complex { … // implicitly final, implements ValueType (But to me it seems better to communicate the “magic” via an interface, even if it is rooted in an annotation.) Implicitly Defined Value Types So far we have been working with nominal value types, which is to say that the sequence of typed components is associated with a name and additional methods that convey the intention of the programmer.  A simple ordered pair of floating point numbers can be variously interpreted as (to name a few possibilities) a rectangular or polar complex number or Cartesian point.  The name and the methods convey the intended meaning. But what if we need a truly simple ordered pair of floating point numbers, without any further conceptual baggage?  Perhaps we are writing a method (like “divideAndRemainder”) which naturally returns a pair of numbers instead of a single number.  Wrapping the pair of numbers in a nominal type (like “QuotientAndRemainder”) makes as little sense as wrapping a single return value in a nominal type (like “Quotient”).  What we need here are structural value types commonly known as tuples. For the present discussion, let us assign a conventional, JVM-friendly name to tuples, roughly as follows: public class java.lang.tuple.$DD extends java.lang.tuple.Tuple {      double $1, $2; } Here the component names are fixed and all the required methods are defined implicitly.  The supertype is an abstract class which has suitable shared declarations.  The name itself mentions a JVM-style method parameter descriptor, which may be “cracked” to determine the number and types of the component fields. The odd thing about such a tuple type (and structural types in general) is it must be instantiated lazily, in response to linkage requests from one or more classes that need it.  The JVM and/or its class loaders must be prepared to spin a tuple type on demand, given a simple name reference, $xyz, where the xyz is cracked into a series of component types.  (Specifics of naming and name mangling need some tasteful engineering.) Tuples also seem to demand, even more than nominal types, some support from the language.  (This is probably because notations for non-nominal types work best as combinations of punctuation and type names, rather than named constructors like Function3 or Tuple2.)  At a minimum, languages with tuples usually (I think) have some sort of simple bracket notation for creating tuples, and a corresponding pattern-matching syntax (or “destructuring bind”) for taking tuples apart, at least when they are parameter lists.  Designing such a syntax is no simple thing, because it ought to play well with nominal value types, and also with pre-existing Java features, such as method parameter lists, implicit conversions, generic types, and reflection.  That is a task for another day. Other Use Cases Besides complex numbers and simple tuples there are many use cases for value types.  Many tuple-like types have natural value-type representations. These include rational numbers, point locations and pixel colors, and various kinds of dates and addresses. Other types have a variable-length ‘tail’ of internal values. The most common example of this is String, which is (mathematically) a sequence of UTF-16 character values. Similarly, bit vectors, multiple-precision numbers, and polynomials are composed of sequences of values. Such types include, in their representation, a reference to a variable-sized data structure (often an array) which (somehow) represents the sequence of values. The value type may also include ’header’ information. Variable-sized values often have a length distribution which favors short lengths. In that case, the design of the value type can make the first few values in the sequence be direct ’header’ fields of the value type. In the common case where the header is enough to represent the whole value, the tail can be a shared null value, or even just a null reference. Note that the tail need not be an immutable object, as long as the header type encapsulates it well enough. This is the case with String, where the tail is a mutable (but never mutated) character array. Field types and their order must be a globally visible part of the API.  The structure of the value type must be transparent enough to have a globally consistent unboxed representation, so that all callers and callees agree about the type and order of components  that appear as parameters, return types, and array elements.  This is a trade-off between efficiency and encapsulation, which is forced on us when we remove an indirection enjoyed by boxed representations.  A JVM-only transformation would not care about such visibility, but a bytecode transformation would need to take care that (say) the components of complex numbers would not get swapped after a redefinition of Complex and a partial recompile.  Perhaps constant pool references to value types need to declare the field order as assumed by each API user. This brings up the delicate status of private fields in a value type.  It must always be possible to load, store, and copy value types as coordinated groups, and the JVM performs those movements by moving individual scalar values between locals and stack.  If a component field is not public, what is to prevent hostile code from plucking it out of the tuple using a rogue aload or astore instruction?  Nothing but the verifier, so we may need to give it more smarts, so that it treats value types as inseparable groups of stack slots or locals (something like long or double). My initial thought was to make the fields always public, which would make the security problem moot.  But public is not always the right answer; consider the case of String, where the underlying mutable character array must be encapsulated to prevent security holes.  I believe we can win back both sides of the tradeoff, by training the verifier never to split up the components in an unboxed value.  Just as the verifier encapsulates the two halves of a 64-bit primitive, it can encapsulate the the header and body of an unboxed String, so that no code other than that of class String itself can take apart the values. Similar to String, we could build an efficient multi-precision decimal type along these lines: public final class DecimalValue extends ValueType {     protected final long header;     protected private final BigInteger digits;     public DecimalValue valueOf(int value, int scale) {         assert(scale >= 0);         return new DecimalValue(((long)value << 32) + scale, null);     }     public DecimalValue valueOf(long value, int scale) {         if (value == (int) value)             return valueOf((int)value, scale);         return new DecimalValue(-scale, new BigInteger(value));     } } Values of this type would be passed between methods as two machine words. Small values (those with a significand which fits into 32 bits) would be represented without any heap data at all, unless the DecimalValue itself were boxed. (Note the tension between encapsulation and unboxing in this case.  It would be better if the header and digits fields were private, but depending on where the unboxing information must “leak”, it is probably safer to make a public revelation of the internal structure.) Note that, although an array of Complex can be faked with a double-length array of double, there is no easy way to fake an array of unboxed DecimalValues.  (Either an array of boxed values or a transposed pair of homogeneous arrays would be reasonable fallbacks, in a current JVM.)  Getting the full benefit of unboxing and arrays will require some new JVM magic. Although the JVM emphasizes portability, system dependent code will benefit from using machine-level types larger than 64 bits.  For example, the back end of a linear algebra package might benefit from value types like Float4 which map to stock vector types.  This is probably only worthwhile if the unboxing arrays can be packed with such values. More Daydreams A more finely-divided design for dynamic enforcement of value safety could feature separate marker interfaces for each invariant.  An empty marker interface Unsynchronizable could cause suitable exceptions for monitor instructions on objects in marked classes.  More radically, a Interchangeable marker interface could cause JVM primitives that are sensitive to object identity to raise exceptions; the strangest result would be that the acmp instruction would have to be specified as raising an exception. @ValueSafe public interface ValueType extends java.io.Serializable,         Unsynchronizable, Interchangeable { … public class Complex implements ValueType {     // inherits Serializable, Unsynchronizable, Interchangeable, @ValueSafe     … It seems possible that Integer and the other wrapper types could be retro-fitted as value-safe types.  This is a major change, since wrapper objects would be unsynchronizable and their references interchangeable.  It is likely that code which violates value-safety for wrapper types exists but is uncommon.  It is less plausible to retro-fit String, since the prominent operation String.intern is often used with value-unsafe code. We should also reconsider the distinction between boxed and unboxed values in code.  The design presented above obscures that distinction.  As another thought experiment, we could imagine making a first class distinction in the type system between boxed and unboxed representations.  Since only primitive types are named with a lower-case initial letter, we could define that the capitalized version of a value type name always refers to the boxed representation, while the initial lower-case variant always refers to boxed.  For example: complex pi = complex.valueOf(Math.PI, 0); Complex boxPi = pi;  // convert to boxed myList.add(boxPi); complex z = myList.get(0);  // unbox Such a convention could perhaps absorb the current difference between int and Integer, double and Double. It might also allow the programmer to express a helpful distinction among array types. As said above, array types are crucial to bulk data interfaces, but are limited in the JVM.  Extending arrays beyond the present limitations is worth thinking about; for example, the Maxine JVM implementation has a hybrid object/array type.  Something like this which can also accommodate value type components seems worthwhile.  On the other hand, does it make sense for value types to contain short arrays?  And why should random-access arrays be the end of our design process, when bulk data is often sequentially accessed, and it might make sense to have heterogeneous streams of data as the natural “jumbo” data structure.  These considerations must wait for another day and another note. More Work It seems to me that a good sequence for introducing such value types would be as follows: Add the value-safety restrictions to an experimental version of javac. Code some sample applications with value types, including Complex and DecimalValue. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. A staggered roll-out like this would decouple language changes from bytecode changes, which is always a convenient thing. A similar investigation should be applied (concurrently) to array types.  In this case, it seems to me that the starting point is in the JVM: Add an experimental unboxing array data structure to a production JVM, perhaps along the lines of Maxine hybrids.  No bytecode or language support is required at first; everything can be done with encapsulated unsafe operations and/or method handles. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. That’s enough musing me for now.  Back to work!

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  • Trying to find USB device on iphone with IOKit.framework

    - by HuGeek
    Hi all, i'm working on a project were i need the usb port to communicate with a external device. I have been looking for exemple on the net (Apple and /developer/IOKit/usb exemple) and trying some other but i can't even find the device. In my code i blocking at the place where the fucntion looks for a next iterator (pointer in fact) with the function getNextIterator but never returns a good value so the code is blocking. By the way i am using toolchain and added IOKit.framework in my project. All i what right now is the communicate or do like a ping to someone on the USB bus!! I blocking in the 'FindDevice'....i can't manage to enter in the while because the variable usbDevice is always = to 0....i have tested my code in a small mac program and it works... Thanks Here is my code : IOReturn ConfigureDevice(IOUSBDeviceInterface **dev) { UInt8 numConfig; IOReturn result; IOUSBConfigurationDescriptorPtr configDesc; //Get the number of configurations result = (*dev)->GetNumberOfConfigurations(dev, &numConfig); if (!numConfig) { return -1; } // Get the configuration descriptor result = (*dev)->GetConfigurationDescriptorPtr(dev, 0, &configDesc); if (result) { NSLog(@"Couldn't get configuration descriptior for index %d (err=%08x)\n", 0, result); return -1; } ifdef OSX_DEBUG NSLog(@"Number of Configurations: %d\n", numConfig); endif // Configure the device result = (*dev)->SetConfiguration(dev, configDesc->bConfigurationValue); if (result) { NSLog(@"Unable to set configuration to value %d (err=%08x)\n", 0, result); return -1; } return kIOReturnSuccess; } IOReturn FindInterfaces(IOUSBDeviceInterface *dev, IOUSBInterfaceInterface **itf) { IOReturn kr; IOUSBFindInterfaceRequest request; io_iterator_t iterator; io_service_t usbInterface; IOUSBInterfaceInterface **intf = NULL; IOCFPlugInInterface **plugInInterface = NULL; HRESULT res; SInt32 score; UInt8 intfClass; UInt8 intfSubClass; UInt8 intfNumEndpoints; int pipeRef; CFRunLoopSourceRef runLoopSource; NSLog(@"Debut FindInterfaces \n"); request.bInterfaceClass = kIOUSBFindInterfaceDontCare; request.bInterfaceSubClass = kIOUSBFindInterfaceDontCare; request.bInterfaceProtocol = kIOUSBFindInterfaceDontCare; request.bAlternateSetting = kIOUSBFindInterfaceDontCare; kr = (*dev)->CreateInterfaceIterator(dev, &request, &iterator); usbInterface = IOIteratorNext(iterator); IOObjectRelease(iterator); NSLog(@"Interface found.\n"); kr = IOCreatePlugInInterfaceForService(usbInterface, kIOUSBInterfaceUserClientTypeID, kIOCFPlugInInterfaceID, &plugInInterface, &score); kr = IOObjectRelease(usbInterface); // done with the usbInterface object now that I have the plugin if ((kIOReturnSuccess != kr) || !plugInInterface) { NSLog(@"unable to create a plugin (%08x)\n", kr); return -1; } // I have the interface plugin. I need the interface interface res = (*plugInInterface)->QueryInterface(plugInInterface, CFUUIDGetUUIDBytes(kIOUSBInterfaceInterfaceID), (LPVOID*) &intf); (*plugInInterface)->Release(plugInInterface); // done with this if (res || !intf) { NSLog(@"couldn't create an IOUSBInterfaceInterface (%08x)\n", (int) res); return -1; } // Now open the interface. This will cause the pipes to be instantiated that are // associated with the endpoints defined in the interface descriptor. kr = (*intf)->USBInterfaceOpen(intf); if (kIOReturnSuccess != kr) { NSLog(@"unable to open interface (%08x)\n", kr); (void) (*intf)->Release(intf); return -1; } kr = (*intf)->CreateInterfaceAsyncEventSource(intf, &runLoopSource); if (kIOReturnSuccess != kr) { NSLog(@"unable to create async event source (%08x)\n", kr); (void) (*intf)->USBInterfaceClose(intf); (void) (*intf)->Release(intf); return -1; } CFRunLoopAddSource(CFRunLoopGetCurrent(), runLoopSource, kCFRunLoopDefaultMode); if (!intf) { NSLog(@"Interface is NULL!\n"); } else { *itf = intf; } NSLog(@"End of FindInterface \n \n"); return kr; } unsigned int FindDevice(void *refCon, io_iterator_t iterator) { kern_return_t kr; io_service_t usbDevice; IOCFPlugInInterface **plugInInterface = NULL; HRESULT result; SInt32 score; UInt16 vendor; UInt16 product; UInt16 release; unsigned int count = 0; NSLog(@"Searching Device....\n"); while (usbDevice = IOIteratorNext(iterator)) { // create intermediate plug-in NSLog(@"Found a device!\n"); kr = IOCreatePlugInInterfaceForService(usbDevice, kIOUSBDeviceUserClientTypeID, kIOCFPlugInInterfaceID, &plugInInterface, &score); kr = IOObjectRelease(usbDevice); if ((kIOReturnSuccess != kr) || !plugInInterface) { NSLog(@"Unable to create a plug-in (%08x)\n", kr); continue; } // Now create the device interface result = (*plugInInterface)->QueryInterface(plugInInterface, CFUUIDGetUUIDBytes(kIOUSBDeviceInterfaceID), (LPVOID)&dev); // Don't need intermediate Plug-In Interface (*plugInInterface)->Release(plugInInterface); if (result || !dev) { NSLog(@"Couldn't create a device interface (%08x)\n", (int)result); continue; } // check these values for confirmation kr = (*dev)->GetDeviceVendor(dev, &vendor); kr = (*dev)->GetDeviceProduct(dev, &product); //kr = (*dev)->GetDeviceReleaseNumber(dev, &release); //if ((vendor != LegoUSBVendorID) || (product != LegoUSBProductID) || (release != LegoUSBRelease)) { if ((vendor != LegoUSBVendorID) || (product != LegoUSBProductID)) { NSLog(@"Found unwanted device (vendor = %d != %d, product = %d != %d, release = %d)\n", vendor, kUSBVendorID, product, LegoUSBProductID, release); (void) (*dev)-Release(dev); continue; } // Open the device to change its state kr = (*dev)->USBDeviceOpen(dev); if (kr == kIOReturnSuccess) { count++; } else { NSLog(@"Unable to open device: %08x\n", kr); (void) (*dev)->Release(dev); continue; } // Configure device kr = ConfigureDevice(dev); if (kr != kIOReturnSuccess) { NSLog(@"Unable to configure device: %08x\n", kr); (void) (*dev)->USBDeviceClose(dev); (void) (*dev)->Release(dev); continue; } break; } return count; } // USB rcx Init IOUSBInterfaceInterface** osx_usb_rcx_init (void) { CFMutableDictionaryRef matchingDict; kern_return_t result; IOUSBInterfaceInterface **intf = NULL; unsigned int device_count = 0; // Create master handler result = IOMasterPort(MACH_PORT_NULL, &gMasterPort); if (result || !gMasterPort) { NSLog(@"ERR: Couldn't create master I/O Kit port(%08x)\n", result); return NULL; } else { NSLog(@"Created Master Port.\n"); NSLog(@"Master port 0x:08X \n \n", gMasterPort); } // Set up the matching dictionary for class IOUSBDevice and its subclasses matchingDict = IOServiceMatching(kIOUSBDeviceClassName); if (!matchingDict) { NSLog(@"Couldn't create a USB matching dictionary \n"); mach_port_deallocate(mach_task_self(), gMasterPort); return NULL; } else { NSLog(@"USB matching dictionary : %08X \n", matchingDict); } CFDictionarySetValue(matchingDict, CFSTR(kUSBVendorID), CFNumberCreate(kCFAllocatorDefault, kCFNumberShortType, &LegoUSBVendorID)); CFDictionarySetValue(matchingDict, CFSTR(kUSBProductID), CFNumberCreate(kCFAllocatorDefault, kCFNumberShortType, &LegoUSBProductID)); result = IOServiceGetMatchingServices(gMasterPort, matchingDict, &gRawAddedIter); matchingDict = 0; // this was consumed by the above call // Iterate over matching devices to access already present devices NSLog(@"RawAddedIter : 0x:%08X \n", &gRawAddedIter); device_count = FindDevice(NULL, gRawAddedIter); if (device_count == 1) { result = FindInterfaces(dev, &intf); if (kIOReturnSuccess != result) { NSLog(@"unable to find interfaces on device: %08x\n", result); (*dev)-USBDeviceClose(dev); (*dev)-Release(dev); return NULL; } // osx_usb_rcx_wakeup(intf); return intf; } else if (device_count 1) { NSLog(@"too many matching devices (%d) !\n", device_count); } else { NSLog(@"no matching devices found\n"); } return NULL; } int main(int argc, char *argv[]) { int returnCode; NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; NSLog(@"Debut du programme \n \n"); osx_usb_rcx_init(); NSLog(@"Fin du programme \n \n"); return 0; // returnCode = UIApplicationMain(argc, argv, @"Untitled1App", @"Untitled1App"); // [pool release]; // return returnCode; }

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