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• Forcing the user to type just Numbers

  - by AZIRAR

  Hey, I have a TextBox and I want that the user type just numbers, not other format. How can I do that ?

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• Fake output stream type

  - by Jeenu

  By default certain programs format their output according to the type of the stream they write to. For example, the output of ls and ls > file looks differently. I'd like to know how this is achieved by a program. Additionally, is there a way by which we can trick such programs as if the output stream is a terminal where it actually is a file (especially when they don't have any options that affect output formatting)?

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• input type=image width being ignored

  - by kastulo

  im making an image button like this: <input type="image" src="red.jpeg" width="150px"> but it is displaying the original image size which is much larger, if i put: <img src="red.jpeg" width="150px"> it displays the image 150px wide as i want, what do you guys think is the problem with this? I have tried styling it with a class and CSS but not working either, please help me with this, im going nuts!!

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• implict type cast in generic method

  - by bitbonk

  why do I get a compiler error in the following code stating: Cannot implicty convert type SpecialNode to T even though T must derive from NodeBase as I defined in the where clause and even though SpecialNode actually derived from NodeBase? public static T GetNode<T>() where T : NodeBase { if (typeof(T) == typeof(SpecialNode)) { return ThisStaticClass.MySpecialNode; // <-- compiler error } if (typeof(T) == typeof(OtherSpecialNode)) { return ThisStaticClass.MyOtherSpecialNode; // <-- compiler error } ... return default(T); }

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• How to make this type of image popping out of box using XHTML css

  - by metal-gear-solid

  How to make this type of image popping out of box using XHTML css. without using whole box along with image as a background Only globe image will be image.

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• How to type in two text fields simulatenously (jQuery)

  - by tester

  I was unsuccessful in finding a jQuery plugin that allowed me to write in two inputs simultaneously. I'm trying to write a normal title in one field, and at the same time type in another input write the same text without special characters or spaces. e.g. Input 1: This is my Title! Input 2: ThisIsMyTitle

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• Postion of & to denote reference type

  - by Matt H

  I was wondering whether to put the ampersand (&) after the variable type or before the variable name. To put it simply, I want to know which one is the conventional style or the standard, or if it is entirely down to preference. int &x; or int& x;

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• Data type changing in Excel file Through c# Program

  - by Anilkumar

  I am generating an excel file through C# code. the cell Data type I'm giving as "" . Once I give Number instead of String The generated Excel could not open. How can I change the Datatype of the cell which I generated through the Code? Thanks in Advance.

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• Type Error In Actionscript 3

  - by sabuj

  i'm working on a flash widget. But it meet some error problem and the error is described bellow- 1. TypeError: Error #1085: The element type "img" must be terminated by the matching end-tag "".

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• Check network connection type

  - by Jufkey

  Hello, How can I programmatically retrieve the current connection type (eg. LAN or Direct connection). InternetGetConnectedState(&ConTypeRet, 0) isn't very reliable. For instance, I'm connected to a wireless network, but ConTypeRet is 18 which is INTERNET_CONNECTION_LAN & INTERNET_RAS_INSTALLED. Isn't there anyway to make sure that ConTypeRet is either INTERNET_CONNECTION_LAN or INTERNET_CONNECTION_MODEM

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• Given a type instance, how to get generic type name in C#?

  - by George Polevoy

  Given a generic type, including List, Nullable how do i get a generic name for C#? var t = typeof(Nullable<DateTime>); var s = t.GetGenericTypeDefinition().Name + "<" + t.GetGenericArguments()[0].Name + ">"; This yields "Nullable`1<DateTime>" , but i need "Nullable<DateTime>" .

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• Text View font type & size in iphone

  - by Harita

  hi i am using below code to change the the font type of text view. but its not changing the font textView3.font = [UIFont fontWithName:@"Helvetica" size:17.0f]; tell me where i am wrong.

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• Custom content type in Microsoft Sharepoint Services.

  - by mablinnikov

  I have to create a library with links to existing files. The files is on the FileChange server. I don't know how to create a custom content type, without the file field. Is it possible at all? P.S. Sorry for my poor English

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• What kind of data type is this?

  - by mystify

  In an class header I have seen something like this: enum { kAudioSessionProperty_PreferredHardwareSampleRate = 'hwsr', // Float64 kAudioSessionProperty_PreferredHardwareIOBufferDuration = 'iobd' // Float32 }; Now I wonder what data type such an kAudioSessionProperty_PreferredHardwareSampleRate actually is? I mean this looks like plain old C, but in Objective-C I would write @"hwsr" if I wanted to make it a string. I want to pass such an "constant" or "enum thing" as argument to an method.

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• How to get Type[] of all classes a class extends

  - by Jeff Dahmer

  You can do Type[] interfaces = typeof(MyClass).GetInterfaces(); to get a list of everything a class implements implements. I am wondering if there is anyway to crawl the "extends" tree to see all the base types a class inherits, i.e. abstract classes etc.?

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• XML XQUERY Problem with NTEXT data type

  - by johnfa

  Hello I want to use XQuery on a column of data type NTEXT (I have no choice!). I have tried converting the column to XML using CONVERT but it gives the error: Incorrect syntax near the keyword 'CONVERT'. Here's the query SELECT y.item.value('@UserID', 'varchar(50)') AS UnitID, y.item.value('@ListingID', 'varchar(100)') AS @ListingID FROM dbo.KB_XMod_Modules CROSS APPLY CONVERT(xml, instancedata).nodes('//instance') AS y(item) (instancedata is my column) Can anyone think of a work around for this ? Thanks

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• Why are function parameters of type size_t?

  - by Grissiom

  The prototype of memset is void *memset(void *s, int c, size_t n);. So why the third parameter is of type size_t ? memset is just an example, I want more general reasons. Thanks in advance.

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• how to get all objects of a given type in javascript

  - by FenchKiss Dev

  I want to retrieve all objects (not DOM elements) of a given type created with the "new" keyword. Is it possible ? function foo(name) { this.name = name; } var obj = new foo(); How can I retrieve a reference to all the foo objects ?

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• No unique bean of type [javax.persistence.EntityManagerFactory] is defined: expected single bean but found 0

  - by user659580

  Can someone tell me what's wrong with my config? I'm overly frustrated and I've been loosing my hair on this. Any pointer will be welcome. Thanks Persistence.xml <?xml version="1.0" encoding="UTF-8"?> <persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"> <persistence-unit name="myPersistenceUnit" transaction-type="JTA"> <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider> <jta-data-source>jdbc/oracle</jta-data-source> <class>com.myproject.domain.UserAccount</class> <properties> <property name="eclipselink.logging.level" value="FINE"/> <property name="eclipselink.jdbc.batch-writing" value="JDBC" /> <property name="eclipselink.target-database" value="Oracle10g"/> <property name="eclipselink.cache.type.default" value="NONE"/> <!--Integrate EclipseLink with JTA in Glassfish--> <property name="eclipselink.target-server" value="SunAS9"/> <property name="eclipselink.cache.size.default" value="0"/> <property name="eclipselink.cache.shared.default" value="false"/> </properties> </persistence-unit> </persistence> Web.xml <?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>MyProject</display-name> <persistence-unit-ref> <persistence-unit-ref-name>persistence/myPersistenceUnit</persistence-unit-ref-name> <persistence-unit-name>myPersistenceUnit</persistence-unit-name> </persistence-unit-ref> <servlet> <servlet-name>mvc-dispatcher</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>mvc-dispatcher</servlet-name> <url-pattern>*.htm</url-pattern> </servlet-mapping> <context-param> <param-name>contextConfigLocation</param-name> <param-value>/WEB-INF/mvc-dispatcher-servlet.xml</param-value> </context-param> <context-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:applicationContext.xml</param-value> </context-param> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> </web-app> applicationContext.xml <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:jee="http://www.springframework.org/schema/jee" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee.xsd" default-autowire="byName"> <tx:annotation-driven/> <tx:jta-transaction-manager/> <jee:jndi-lookup id="entityManagerFactory" jndi-name="persistence/myPersistenceUnit"/> <bean class="org.springframework.beans.factory.annotation.RequiredAnnotationBeanPostProcessor"/> <bean class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor"/> <!-- enables interpretation of the @PersistenceUnit/@PersistenceContext annotations providing convenient access to EntityManagerFactory/EntityManager --> <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor"/> </beans> mvc-dispatcher-servlet.xml <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd"> <!-- DispatcherServlet Context: defines this servlet's request-processing infrastructure --> <tx:annotation-driven /> <tx:jta-transaction-manager /> <context:component-scan base-package="com.myProject" /> <context:annotation-config /> <!-- Enables the Spring MVC @Controller programming model --> <mvc:annotation-driven /> <mvc:default-servlet-handler /> <bean class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping" /> <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter" /> <!-- Location Tiles config --> <bean id="tilesConfigurer" class="org.springframework.web.servlet.view.tiles2.TilesConfigurer"> <property name="definitions"> <list> <value>/WEB-INF/tiles-defs.xml</value> </list> </property> </bean> <!-- Resolves views selected for rendering by Tiles --> <bean id="tilesViewResolver" class="org.springframework.web.servlet.view.UrlBasedViewResolver" p:viewClass="org.springframework.web.servlet.view.tiles2.TilesView" /> <!-- Resolves views selected for rendering by @Controllers to .jsp resources in the /WEB-INF/views directory --> <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix"> <value>/WEB-INF/pages/</value> </property> <property name="suffix"> <value>.jsp</value> </property> </bean> <bean id="messageSource" class="org.springframework.context.support.ReloadableResourceBundleMessageSource"> <property name="basename" value="/WEB-INF/messages" /> <property name="cacheSeconds" value="0"/> </bean> <bean id="validator" class="org.springframework.validation.beanvalidation.LocalValidatorFactoryBean" /> </beans> UserAccountDAO.java @Repository public class UserAccountDAO implements IUserAccountDAO { private EntityManager entityManager; @PersistenceContext public void setEntityManager(EntityManager entityManager) { this.entityManager = entityManager; } @Override @Transactional(readOnly = true, propagation = Propagation.REQUIRED) public UserAccount checkLogin(String userName, String pwd) { //* Find the user in the DB Query queryUserAccount = entityManager.createQuery("select u from UserAccount u where (u.username = :userName) and (u.password = :pwd)"); ....... } } loginController.java @Controller @SessionAttributes({"userAccount"}) public class LoginLogOutController { private static final Logger logger = LoggerFactory.getLogger(UserAccount.class); @Resource private UserAccountDAO userDAO; @RequestMapping(value="/loginForm.htm", method = RequestMethod.GET) public String showloginForm(Map model) { logger.debug("Get login form"); UserAccount userAccount = new UserAccount(); model.put("userAccount", userAccount); return "loginform"; } ... Error Stack INFO: 13:52:21,657 ERROR ContextLoader:220 - Context initialization failed org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'loginController': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userAccountDAO': Injection of persistence dependencies failed; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No unique bean of type [javax.persistence.EntityManagerFactory] is defined: expected single bean but found 0 at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessPropertyValues(CommonAnnotationBeanPostProcessor.java:300) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1074) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:190) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:580) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425) at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:276) at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:197) at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:47) at org.apache.catalina.core.StandardContext.contextListenerStart(StandardContext.java:4664) at com.sun.enterprise.web.WebModule.contextListenerStart(WebModule.java:535) at org.apache.catalina.core.StandardContext.start(StandardContext.java:5266) at com.sun.enterprise.web.WebModule.start(WebModule.java:499) at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:928) at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:912) at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:694) at com.sun.enterprise.web.WebContainer.loadWebModule(WebContainer.java:1947) at com.sun.enterprise.web.WebContainer.loadWebModule(WebContainer.java:1619) at com.sun.enterprise.web.WebApplication.start(WebApplication.java:90) at org.glassfish.internal.data.EngineRef.start(EngineRef.java:126) at org.glassfish.internal.data.ModuleInfo.start(ModuleInfo.java:241) at org.glassfish.internal.data.ApplicationInfo.start(ApplicationInfo.java:236) at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:339) at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:183) at org.glassfish.deployment.admin.DeployCommand.execute(DeployCommand.java:272) at com.sun.enterprise.v3.admin.CommandRunnerImpl$1.execute(CommandRunnerImpl.java:305) at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:320) at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:1176) at com.sun.enterprise.v3.admin.CommandRunnerImpl.access$900(CommandRunnerImpl.java:83) at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1235) at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1224) at com.sun.enterprise.v3.admin.AdminAdapter.doCommand(AdminAdapter.java:365) at com.sun.enterprise.v3.admin.AdminAdapter.service(AdminAdapter.java:204) at com.sun.grizzly.tcp.http11.GrizzlyAdapter.service(GrizzlyAdapter.java:166) at com.sun.enterprise.v3.server.HK2Dispatcher.dispath(HK2Dispatcher.java:100) at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:245) at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:791) at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:693) at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:954) at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:170) at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:135) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:102) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:88) at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:76) at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:53) at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:57) at com.sun.grizzly.ContextTask.run(ContextTask.java:69) at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:330) at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:309) at java.lang.Thread.run(Thread.java:732)

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• Understanding Request Validation in ASP.NET MVC 3

  - by imran_ku07

       Introduction:             A fact that you must always remember "never ever trust user inputs". An application that trusts user inputs may be easily vulnerable to XSS, XSRF, SQL Injection, etc attacks. XSS and XSRF are very dangerous attacks. So to mitigate these attacks ASP.NET introduced request validation in ASP.NET 1.1. During request validation, ASP.NET will throw HttpRequestValidationException: 'A potentially dangerous XXX value was detected from the client', if he found, < followed by an exclamation(like <!) or < followed by the letters a through z(like <s) or & followed by a pound sign(like &#123) as a part of query string, posted form and cookie collection. In ASP.NET 4.0, request validation becomes extensible. This means that you can extend request validation. Also in ASP.NET 4.0, by default request validation is enabled before the BeginRequest phase of an HTTP request. ASP.NET MVC 3 moves one step further by making request validation granular. This allows you to disable request validation for some properties of a model while maintaining request validation for all other cases. In this article I will show you the use of request validation in ASP.NET MVC 3. Then I will briefly explain the internal working of granular request validation.       Description:             First of all create a new ASP.NET MVC 3 application. Then create a simple model class called MyModel,     public class MyModel { public string Prop1 { get; set; } public string Prop2 { get; set; } }             Then just update the index action method as follows,   public ActionResult Index(MyModel p) { return View(); }             Now just run this application. You will find that everything works just fine. Now just append this query string ?Prop1=<s to the url of this application, you will get the HttpRequestValidationException exception.           Now just decorate the Index action method with [ValidateInputAttribute(false)],   [ValidateInput(false)] public ActionResult Index(MyModel p) { return View(); }             Run this application again with same query string. You will find that your application run without any unhandled exception.           Up to now, there is nothing new in ASP.NET MVC 3 because ValidateInputAttribute was present in the previous versions of ASP.NET MVC. Any problem with this approach? Yes there is a problem with this approach. The problem is that now users can send html for both Prop1 and Prop2 properties and a lot of developers are not aware of it. This means that now everyone can send html with both parameters(e.g, ?Prop1=<s&Prop2=<s). So ValidateInput attribute does not gives you the guarantee that your application is safe to XSS or XSRF. This is the reason why ASP.NET MVC team introduced granular request validation in ASP.NET MVC 3. Let's see this feature.           Remove [ValidateInputAttribute(false)] on Index action and update MyModel class as follows,   public class MyModel { [AllowHtml] public string Prop1 { get; set; } public string Prop2 { get; set; } }             Note that AllowHtml attribute is only decorated on Prop1 property. Run this application again with ?Prop1=<s query string. You will find that your application run just fine. Run this application again with ?Prop1=<s&Prop2=<s query string, you will get HttpRequestValidationException exception. This shows that the granular request validation in ASP.NET MVC 3 only allows users to send html for properties decorated with AllowHtml attribute.            Sometimes you may need to access Request.QueryString or Request.Form directly. You may change your code as follows,   [ValidateInput(false)] public ActionResult Index() { var prop1 = Request.QueryString["Prop1"]; return View(); }             Run this application again, you will get the HttpRequestValidationException exception again even you have [ValidateInput(false)] on your Index action. The reason is that Request flags are still not set to unvalidate. I will explain this later. For making this work you need to use Unvalidated extension method,     public ActionResult Index() { var q = Request.Unvalidated().QueryString; var prop1 = q["Prop1"]; return View(); }             Unvalidated extension method is defined in System.Web.Helpers namespace . So you need to add using System.Web.Helpers; in this class file. Run this application again, your application run just fine.             There you have it. If you are not curious to know the internal working of granular request validation then you can skip next paragraphs completely. If you are interested then carry on reading.             Create a new ASP.NET MVC 2 application, then open global.asax.cs file and the following lines,     protected void Application_BeginRequest() { var q = Request.QueryString; }             Then make the Index action method as,    [ValidateInput(false)] public ActionResult Index(string id) { return View(); }             Please note that the Index action method contains a parameter and this action method is decorated with [ValidateInput(false)]. Run this application again, but now with ?id=<s query string, you will get HttpRequestValidationException exception at Application_BeginRequest method. Now just add the following entry in web.config,   <httpRuntime requestValidationMode="2.0"/>             Now run this application again. This time your application will run just fine. Now just see the following quote from ASP.NET 4 Breaking Changes,   In ASP.NET 4, by default, request validation is enabled for all requests, because it is enabled before the BeginRequest phase of an HTTP request. As a result, request validation applies to requests for all ASP.NET resources, not just .aspx page requests. This includes requests such as Web service calls and custom HTTP handlers. Request validation is also active when custom HTTP modules are reading the contents of an HTTP request.             This clearly state that request validation is enabled before the BeginRequest phase of an HTTP request. For understanding what does enabled means here, we need to see HttpRequest.ValidateInput, HttpRequest.QueryString and HttpRequest.Form methods/properties in System.Web assembly. Here is the implementation of HttpRequest.ValidateInput, HttpRequest.QueryString and HttpRequest.Form methods/properties in System.Web assembly,     public NameValueCollection Form { get { if (this._form == null) { this._form = new HttpValueCollection(); if (this._wr != null) { this.FillInFormCollection(); } this._form.MakeReadOnly(); } if (this._flags[2]) { this._flags.Clear(2); this.ValidateNameValueCollection(this._form, RequestValidationSource.Form); } return this._form; } } public NameValueCollection QueryString { get { if (this._queryString == null) { this._queryString = new HttpValueCollection(); if (this._wr != null) { this.FillInQueryStringCollection(); } this._queryString.MakeReadOnly(); } if (this._flags[1]) { this._flags.Clear(1); this.ValidateNameValueCollection(this._queryString, RequestValidationSource.QueryString); } return this._queryString; } } public void ValidateInput() { if (!this._flags[0x8000]) { this._flags.Set(0x8000); this._flags.Set(1); this._flags.Set(2); this._flags.Set(4); this._flags.Set(0x40); this._flags.Set(0x80); this._flags.Set(0x100); this._flags.Set(0x200); this._flags.Set(8); } }             The above code indicates that HttpRequest.QueryString and HttpRequest.Form will only validate the querystring and form collection if certain flags are set. These flags are automatically set if you call HttpRequest.ValidateInput method. Now run the above application again(don't forget to append ?id=<s query string in the url) with the same settings(i.e, requestValidationMode="2.0" setting in web.config and Application_BeginRequest method in global.asax.cs), your application will run just fine. Now just update the Application_BeginRequest method as,   protected void Application_BeginRequest() { Request.ValidateInput(); var q = Request.QueryString; }             Note that I am calling Request.ValidateInput method prior to use Request.QueryString property. ValidateInput method will internally set certain flags(discussed above). These flags will then tells the Request.QueryString (and Request.Form) property that validate the query string(or form) when user call Request.QueryString(or Request.Form) property. So running this application again with ?id=<s query string will throw HttpRequestValidationException exception. Now I hope it is clear to you that what does requestValidationMode do. It just tells the ASP.NET that not invoke the Request.ValidateInput method internally before the BeginRequest phase of an HTTP request if requestValidationMode is set to a value less than 4.0 in web.config. Here is the implementation of HttpRequest.ValidateInputIfRequiredByConfig method which will prove this statement(Don't be confused with HttpRequest and Request. Request is the property of HttpRequest class),    internal void ValidateInputIfRequiredByConfig() { ............................................................... ............................................................... ............................................................... ............................................................... if (httpRuntime.RequestValidationMode >= VersionUtil.Framework40) { this.ValidateInput(); } }              Hopefully the above discussion will clear you how requestValidationMode works in ASP.NET 4. It is also interesting to note that both HttpRequest.QueryString and HttpRequest.Form only throws the exception when you access them first time. Any subsequent access to HttpRequest.QueryString and HttpRequest.Form will not throw any exception. Continuing with the above example, just update Application_BeginRequest method in global.asax.cs file as,   protected void Application_BeginRequest() { try { var q = Request.QueryString; var f = Request.Form; } catch//swallow this exception { } var q1 = Request.QueryString; var f1 = Request.Form; }             Without setting requestValidationMode to 2.0 and without decorating ValidateInput attribute on Index action, your application will work just fine because both HttpRequest.QueryString and HttpRequest.Form will clear their flags after reading HttpRequest.QueryString and HttpRequest.Form for the first time(see the implementation of HttpRequest.QueryString and HttpRequest.Form above).           Now let's see ASP.NET MVC 3 granular request validation internal working. First of all we need to see type of HttpRequest.QueryString and HttpRequest.Form properties. Both HttpRequest.QueryString and HttpRequest.Form properties are of type NameValueCollection which is inherited from the NameObjectCollectionBase class. NameObjectCollectionBase class contains _entriesArray, _entriesTable, NameObjectEntry.Key and NameObjectEntry.Value fields which granular request validation uses internally. In addition granular request validation also uses _queryString, _form and _flags fields, ValidateString method and the Indexer of HttpRequest class. Let's see when and how granular request validation uses these fields.           Create a new ASP.NET MVC 3 application. Then put a breakpoint at Application_BeginRequest method and another breakpoint at HomeController.Index method. Now just run this application. When the break point inside Application_BeginRequest method hits then add the following expression in quick watch window, System.Web.HttpContext.Current.Request.QueryString. You will see the following screen,                                              Now Press F5 so that the second breakpoint inside HomeController.Index method hits. When the second breakpoint hits then add the following expression in quick watch window again, System.Web.HttpContext.Current.Request.QueryString. You will see the following screen,                            First screen shows that _entriesTable field is of type System.Collections.Hashtable and _entriesArray field is of type System.Collections.ArrayList during the BeginRequest phase of the HTTP request. While the second screen shows that _entriesTable type is changed to Microsoft.Web.Infrastructure.DynamicValidationHelper.LazilyValidatingHashtable and _entriesArray type is changed to Microsoft.Web.Infrastructure.DynamicValidationHelper.LazilyValidatingArrayList during executing the Index action method. In addition to these members, ASP.NET MVC 3 also perform some operation on _flags, _form, _queryString and other members of HttpRuntime class internally. This shows that ASP.NET MVC 3 performing some operation on the members of HttpRequest class for making granular request validation possible.           Both LazilyValidatingArrayList and LazilyValidatingHashtable classes are defined in the Microsoft.Web.Infrastructure assembly. You may wonder why their name starts with Lazily. The fact is that now with ASP.NET MVC 3, request validation will be performed lazily. In simple words, Microsoft.Web.Infrastructure assembly is now taking the responsibility for request validation from System.Web assembly. See the below screens. The first screen depicting HttpRequestValidationException exception in ASP.NET MVC 2 application while the second screen showing HttpRequestValidationException exception in ASP.NET MVC 3 application.   In MVC 2:                 In MVC 3:                          The stack trace of the second screenshot shows that Microsoft.Web.Infrastructure assembly (instead of System.Web assembly) is now performing request validation in ASP.NET MVC 3. Now you may ask: where Microsoft.Web.Infrastructure assembly is performing some operation on the members of HttpRequest class. There are at least two places where the Microsoft.Web.Infrastructure assembly performing some operation , Microsoft.Web.Infrastructure.DynamicValidationHelper.GranularValidationReflectionUtil.GetInstance method and Microsoft.Web.Infrastructure.DynamicValidationHelper.ValidationUtility.CollectionReplacer.ReplaceCollection method, Here is the implementation of these methods,   private static GranularValidationReflectionUtil GetInstance() { try { if (DynamicValidationShimReflectionUtil.Instance != null) { return null; } GranularValidationReflectionUtil util = new GranularValidationReflectionUtil(); Type containingType = typeof(NameObjectCollectionBase); string fieldName = "_entriesArray"; bool isStatic = false; Type fieldType = typeof(ArrayList); FieldInfo fieldInfo = CommonReflectionUtil.FindField(containingType, fieldName, isStatic, fieldType); util._del_get_NameObjectCollectionBase_entriesArray = MakeFieldGetterFunc<NameObjectCollectionBase, ArrayList>(fieldInfo); util._del_set_NameObjectCollectionBase_entriesArray = MakeFieldSetterFunc<NameObjectCollectionBase, ArrayList>(fieldInfo); Type type6 = typeof(NameObjectCollectionBase); string str2 = "_entriesTable"; bool flag2 = false; Type type7 = typeof(Hashtable); FieldInfo info2 = CommonReflectionUtil.FindField(type6, str2, flag2, type7); util._del_get_NameObjectCollectionBase_entriesTable = MakeFieldGetterFunc<NameObjectCollectionBase, Hashtable>(info2); util._del_set_NameObjectCollectionBase_entriesTable = MakeFieldSetterFunc<NameObjectCollectionBase, Hashtable>(info2); Type targetType = CommonAssemblies.System.GetType("System.Collections.Specialized.NameObjectCollectionBase+NameObjectEntry"); Type type8 = targetType; string str3 = "Key"; bool flag3 = false; Type type9 = typeof(string); FieldInfo info3 = CommonReflectionUtil.FindField(type8, str3, flag3, type9); util._del_get_NameObjectEntry_Key = MakeFieldGetterFunc<string>(targetType, info3); Type type10 = targetType; string str4 = "Value"; bool flag4 = false; Type type11 = typeof(object); FieldInfo info4 = CommonReflectionUtil.FindField(type10, str4, flag4, type11); util._del_get_NameObjectEntry_Value = MakeFieldGetterFunc<object>(targetType, info4); util._del_set_NameObjectEntry_Value = MakeFieldSetterFunc(targetType, info4); Type type12 = typeof(HttpRequest); string methodName = "ValidateString"; bool flag5 = false; Type[] argumentTypes = new Type[] { typeof(string), typeof(string), typeof(RequestValidationSource) }; Type returnType = typeof(void); MethodInfo methodInfo = CommonReflectionUtil.FindMethod(type12, methodName, flag5, argumentTypes, returnType); util._del_validateStringCallback = CommonReflectionUtil.MakeFastCreateDelegate<HttpRequest, ValidateStringCallback>(methodInfo); Type type = CommonAssemblies.SystemWeb.GetType("System.Web.HttpValueCollection"); util._del_HttpValueCollection_ctor = CommonReflectionUtil.MakeFastNewObject<Func<NameValueCollection>>(type); Type type14 = typeof(HttpRequest); string str6 = "_form"; bool flag6 = false; Type type15 = type; FieldInfo info6 = CommonReflectionUtil.FindField(type14, str6, flag6, type15); util._del_get_HttpRequest_form = MakeFieldGetterFunc<HttpRequest, NameValueCollection>(info6); util._del_set_HttpRequest_form = MakeFieldSetterFunc(typeof(HttpRequest), info6); Type type16 = typeof(HttpRequest); string str7 = "_queryString"; bool flag7 = false; Type type17 = type; FieldInfo info7 = CommonReflectionUtil.FindField(type16, str7, flag7, type17); util._del_get_HttpRequest_queryString = MakeFieldGetterFunc<HttpRequest, NameValueCollection>(info7); util._del_set_HttpRequest_queryString = MakeFieldSetterFunc(typeof(HttpRequest), info7); Type type3 = CommonAssemblies.SystemWeb.GetType("System.Web.Util.SimpleBitVector32"); Type type18 = typeof(HttpRequest); string str8 = "_flags"; bool flag8 = false; Type type19 = type3; FieldInfo flagsFieldInfo = CommonReflectionUtil.FindField(type18, str8, flag8, type19); Type type20 = type3; string str9 = "get_Item"; bool flag9 = false; Type[] typeArray4 = new Type[] { typeof(int) }; Type type21 = typeof(bool); MethodInfo itemGetter = CommonReflectionUtil.FindMethod(type20, str9, flag9, typeArray4, type21); Type type22 = type3; string str10 = "set_Item"; bool flag10 = false; Type[] typeArray6 = new Type[] { typeof(int), typeof(bool) }; Type type23 = typeof(void); MethodInfo itemSetter = CommonReflectionUtil.FindMethod(type22, str10, flag10, typeArray6, type23); MakeRequestValidationFlagsAccessors(flagsFieldInfo, itemGetter, itemSetter, out util._del_BitVector32_get_Item, out util._del_BitVector32_set_Item); return util; } catch { return null; } } private static void ReplaceCollection(HttpContext context, FieldAccessor<NameValueCollection> fieldAccessor, Func<NameValueCollection> propertyAccessor, Action<NameValueCollection> storeInUnvalidatedCollection, RequestValidationSource validationSource, ValidationSourceFlag validationSourceFlag) { NameValueCollection originalBackingCollection; ValidateStringCallback validateString; SimpleValidateStringCallback simpleValidateString; Func<NameValueCollection> getActualCollection; Action<NameValueCollection> makeCollectionLazy; HttpRequest request = context.Request; Func<bool> getValidationFlag = delegate { return _reflectionUtil.GetRequestValidationFlag(request, validationSourceFlag); }; Func<bool> func = delegate { return !getValidationFlag(); }; Action<bool> setValidationFlag = delegate (bool value) { _reflectionUtil.SetRequestValidationFlag(request, validationSourceFlag, value); }; if ((fieldAccessor.Value != null) && func()) { storeInUnvalidatedCollection(fieldAccessor.Value); } else { originalBackingCollection = fieldAccessor.Value; validateString = _reflectionUtil.MakeValidateStringCallback(context.Request); simpleValidateString = delegate (string value, string key) { if (((key == null) || !key.StartsWith("__", StringComparison.Ordinal)) && !string.IsNullOrEmpty(value)) { validateString(value, key, validationSource); } }; getActualCollection = delegate { fieldAccessor.Value = originalBackingCollection; bool flag = getValidationFlag(); setValidationFlag(false); NameValueCollection col = propertyAccessor(); setValidationFlag(flag); storeInUnvalidatedCollection(new NameValueCollection(col)); return col; }; makeCollectionLazy = delegate (NameValueCollection col) { simpleValidateString(col[null], null); LazilyValidatingArrayList array = new LazilyValidatingArrayList(_reflectionUtil.GetNameObjectCollectionEntriesArray(col), simpleValidateString); _reflectionUtil.SetNameObjectCollectionEntriesArray(col, array); LazilyValidatingHashtable table = new LazilyValidatingHashtable(_reflectionUtil.GetNameObjectCollectionEntriesTable(col), simpleValidateString); _reflectionUtil.SetNameObjectCollectionEntriesTable(col, table); }; Func<bool> hasValidationFired = func; Action disableValidation = delegate { setValidationFlag(false); }; Func<int> fillInActualFormContents = delegate { NameValueCollection values = getActualCollection(); makeCollectionLazy(values); return values.Count; }; DeferredCountArrayList list = new DeferredCountArrayList(hasValidationFired, disableValidation, fillInActualFormContents); NameValueCollection target = _reflectionUtil.NewHttpValueCollection(); _reflectionUtil.SetNameObjectCollectionEntriesArray(target, list); fieldAccessor.Value = target; } }             Hopefully the above code will help you to understand the internal working of granular request validation. It is also important to note that Microsoft.Web.Infrastructure assembly invokes HttpRequest.ValidateInput method internally. For further understanding please see Microsoft.Web.Infrastructure assembly code. Finally you may ask: at which stage ASP NET MVC 3 will invoke these methods. You will find this answer by looking at the following method source,   Unvalidated extension method for HttpRequest class defined in System.Web.Helpers.Validation class. System.Web.Mvc.MvcHandler.ProcessRequestInit method. System.Web.Mvc.ControllerActionInvoker.ValidateRequest method. System.Web.WebPages.WebPageHttpHandler.ProcessRequestInternal method.       Summary:             ASP.NET helps in preventing XSS attack using a feature called request validation. In this article, I showed you how you can use granular request validation in ASP.NET MVC 3. I explain you the internal working of  granular request validation. Hope you will enjoy this article too.   SyntaxHighlighter.all()

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• Logical Domain Modeling Made Simple

  - by Knut Vatsendvik

  How can logical domain modeling be made simple and collaborative? Many non-technical end-users, managers and business domain experts find it difficult to understand the visual models offered by many UML tools. This creates trouble in capturing and verifying the information that goes into a logical domain model. The tools are also too advanced and complex for a non-technical user to learn and use. We have therefore, in our current project, ended up with using Confluence as tool for designing the logical domain model with the help of a few very useful plugins. Big thanks to Ole Nymoen and Per Spilling for their expertise in this field that made this posting possible. Confluence Plugins Here is a list of Confluence plugins used in this solution. Install these before trying out the macros used below. Plugin Description Copy Space Allows a space administrator to copy a space, including the pages within the space Metadata Supports adding metadata to Wiki pages Label Manages labeling of pages Linking Contains macros for linking to templates, the dashboard and other Table Enhances the table capability in Confluence Creating a Confluence Space First we need to create a new confluence space for the domain model. Click the link Create a Space located below the list of spaces on the Dashboard. Please contact your Confluence administrator is you do not have permissions to do this.   For illustrative purpose all attributes and entities in this posting are based on my imaginary project manager domain model. When a logical domain model is good enough for being implemented, do a copy of the Confluence Space (see Copy Space plugin). In this way you create a stable version of the logical domain model while further design can continue with the new copied space. Typical will the implementation phase result in a database design and/or a XSD schema design. Add Space Templates Go to the Home page of your Confluence Space. Navigate to the Browse drop-down menu and click on Advanced. Then click the Templates option in the left navigation panel. Click Add New Space Template to add the following three templates. Name: attribute {metadata-list} || Name | | || Type | | || Format | | || Description | | {metadata-list} {add-label:attribute} Name: primary-type {metadata-list} || Name | || || Type | || || Format | || || Description | || {metadata-list} {add-label:primary-type} Name: complex-type {metadata-list} || Name | || || Description |  || {metadata-list} h3. Attributes || Name || Type || Format || Description || | [name] | {metadata-from:name|Type} | {metadata-from:name|Format} | {metadata-from:name|Description} | {add-label:complex-type,entity} The metadata-list macro (see Metadata plugin) will save a list of metadata values to the page. The add-label macro (see Label plugin) will automatically label the page. Primary Types Page Our first page to add will act as container for our primary types. Switch to Wiki markup when adding the following content to the page. | (+) {add-page:template=primary-type|parent=@self}Add new primary type{add-page} | {metadata-report:Name,Type,Format,Description|sort=Name|root=@self|pages=@descendents} Once the page is created, click the Add new primary type (create-page macro) to start creating a new pages. Here is an example of input to the LocalDate page. Embrace the LocalDate with square brackets [] to make the page linkable. Again switch to Wiki markup before editing. {metadata-list} || Name | [LocalDate] || || Type | Date || || Format | YYYY-MM-DD || || Description | Date in local time zone. YYYY = year, MM = month and DD = day || {metadata-list} {add-label:primary-type} The metadata-report macro will show a tabular report of all child pages.   Attributes Page The next page will act as container for all of our attributes. | (+) {add-page:template=attribute|parent=@self|title=attribute}Add new attribute{add-page} | {metadata-report:Name,Type,Format,Description|sort=Name|pages=@descendants} Here is an example of input to the startDate page. {metadata-list} || Name | [startDate] || || Type | [LocalDate] || || Format | {metadata-from:LocalDate|Format} || || Description | The projects start date || {metadata-list} {add-label:attribute} Using the metadata-from macro we fetch the text from the previously created LocalDate page. Complex Types Page The last page in this example shows how attributes can be combined together to form more complex types.   h3. Intro Overview of complex types in the domain model. | (+) {add-page:template=complex-type|parent=@self}Add a new complex type{add-page}\\ | {metadata-report:Name,Description|sort=Name|root=@self|pages=@descendents} Here is an example of input to the ProjectType page. {metadata-list} || Name | [ProjectType] || || Description | Represents a project || {metadata-list} h3. Attributes || Name || Type || Format || Description || | [projectId] | {metadata-from:projectId|Type} | {metadata-from:projectId|Format} | {metadata-from:projectId|Description} | | [name] | {metadata-from:name|Type} | {metadata-from:name|Format} | {metadata-from:name|Description} | | [description] | {metadata-from:description|Type} | {metadata-from:description|Format} | {metadata-from:description|Description} | | [startDate] | {metadata-from:startDate|Type} | {metadata-from:startDate|Format} | {metadata-from:startDate|Description} | {add-label:complex-type,entity} Gives us this Conclusion Using a web-based corporate Wiki like Confluence to create a logical domain model increases the collaboration between people with different roles in the enterprise. It’s my believe that this helps the domain model to be more accurate, and better documented. In our real project we have more pages than illustrated here to complete the documentation. We do also still use UML tools to create different types of diagrams that Confluence do not support. As a last tip, an ImageMap plugin can make those diagrams clickable when used in pages. Enjoy!

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• How to tell the Browser the character encoding of a HTML website regardless of Server Content.-Type Headers?

  - by hakre

  I have a HTML page that correctly (the encoding of the physical on disk matches it) announces it's Content-Type: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="Content-Type" content= "text/html; charset=utf-8"> <title> ... Opening the file from disk in browser (Google Chrome, Firefox) works fine. Requesting it via HTTP, the webserver sends a different Content-Type header: $ curl -I http:/example.com/file.html HTTP/1.1 200 OK Date: Fri, 19 Oct 2012 10:57:13 GMT ... Content-Type: text/html; charset=ISO-8859-1 (see last line). The browser then uses ISO-8859-1 to display which is an unwanted result. Is there a common way to override the server headers send to the browser from within the HTML document?

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• Apache is sending php files to my browser instead of parsing

  - by justen doherty

  I have to set up PHP on an existing web host. I have made a virtual host entry, but for some reason Apache is sending the PHP to the browser instead of parsing.. from googling around it looks like it's a problem with the mimetypes, but I'm not an Apache expert by any means, so if anyone could help it would be appreciated... I have the following in my httpd.conf: AddHandler php5-script php DirectoryIndex index.html index.phtml index.php index.phps AddType application/x-httpd-php .phtml AddType application/x-httpd-php .php AddType application/x-httpd-php-source .phps The PHP module is loaded into Apache: /usr/sbin/apachectl -M Loaded Modules: core_module (static) mpm_prefork_module (static) http_module (static) so_module (static) auth_basic_module (shared) auth_digest_module (shared) authn_file_module (shared) authn_alias_module (shared) authn_anon_module (shared) authn_dbm_module (shared) authn_default_module (shared) authz_host_module (shared) authz_user_module (shared) authz_owner_module (shared) authz_groupfile_module (shared) authz_dbm_module (shared) authz_default_module (shared) ldap_module (shared) authnz_ldap_module (shared) include_module (shared) log_config_module (shared) logio_module (shared) env_module (shared) ext_filter_module (shared) mime_magic_module (shared) expires_module (shared) deflate_module (shared) headers_module (shared) usertrack_module (shared) setenvif_module (shared) mime_module (shared) dav_module (shared) status_module (shared) autoindex_module (shared) info_module (shared) dav_fs_module (shared) vhost_alias_module (shared) negotiation_module (shared) dir_module (shared) actions_module (shared) speling_module (shared) userdir_module (shared) alias_module (shared) rewrite_module (shared) proxy_module (shared) proxy_balancer_module (shared) proxy_ftp_module (shared) proxy_http_module (shared) proxy_connect_module (shared) cache_module (shared) suexec_module (shared) disk_cache_module (shared) file_cache_module (shared) mem_cache_module (shared) cgi_module (shared) version_module (shared) fcgid_module (shared) perl_module (shared) php5_module (shared) proxy_ajp_module (shared) ssl_module (shared) And this is my virtual host entry: <VirtualHost 10.16.140.113:80> ServerName viridor-cms.co.uk ServerAlias www.viridor-cms.co.uk UseCanonicalName Off DocumentRoot /var/www/vhosts/viridor-cms.co.uk/httpdocs CustomLog /var/www/vhosts/viridor-cms.co.uk/cms-access_log common ErrorLog /var/www/vhosts/viridor-cms.co.uk/cms-error_log DirectoryIndex index.php index.html <IfModule sapi_apache2.c> php_admin_flag engine on php_admin_flag safe_mode on </IfModule> <IfModule mod_php5.c> php_admin_flag engine on php_admin_flag safe_mode on </IfModule> AddType application/x-httpd-php .php AddType application/x-httpd-php-source .phps </VirtualHost> Please help, my head is so sore from banging it against the table and the wall!

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• C#/.NET Little Wonders: The Generic Func 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. Back in one of my three original “Little Wonders” Trilogy of posts, I had listed generic delegates as one of the Little Wonders of .NET.  Later, someone posted a comment saying said that they would love more detail on the generic delegates and their uses, since my original entry just scratched the surface of them. Last week, I began our look at some of the handy generic delegates built into .NET with a description of delegates in general, and the Action family of delegates.  For this week, I’ll launch into a look at the Func family of generic delegates and how they can be used to support generic, reusable algorithms and classes. Quick Delegate Recap Delegates are similar to function pointers in C++ in that they allow you to store a reference to a method.  They can store references to either static or instance methods, and can actually be used to chain several methods together in one delegate. Delegates are very type-safe and can be satisfied with any standard method, anonymous method, or a lambda expression.  They can also be null as well (refers to no method), so care should be taken to make sure that the delegate is not null before you invoke it. Delegates are defined using the keyword delegate, where the delegate’s type name is placed where you would typically place the method name: 1: // This delegate matches any method that takes string, returns nothing 2: public delegate void Log(string message); This delegate defines a delegate type named Log that can be used to store references to any method(s) that satisfies its signature (whether instance, static, lambda expression, etc.). Delegate instances then can be assigned zero (null) or more methods using the operator = which replaces the existing delegate chain, or by using the operator += which adds a method to the end of a delegate chain: 1: // creates a delegate instance named currentLogger defaulted to Console.WriteLine (static method) 2: Log currentLogger = Console.Out.WriteLine; 3:  4: // invokes the delegate, which writes to the console out 5: currentLogger("Hi Standard Out!"); 6:  7: // append a delegate to Console.Error.WriteLine to go to std error 8: currentLogger += Console.Error.WriteLine; 9:  10: // invokes the delegate chain and writes message to std out and std err 11: currentLogger("Hi Standard Out and Error!"); While delegates give us a lot of power, it can be cumbersome to re-create fairly standard delegate definitions repeatedly, for this purpose the generic delegates were introduced in various stages in .NET.  These support various method types with particular signatures. Note: a caveat with generic delegates is that while they can support multiple parameters, they do not match methods that contains ref or out parameters. If you want to a delegate to represent methods that takes ref or out parameters, you will need to create a custom delegate. We’ve got the Func… delegates Just like it’s cousin, the Action delegate family, the Func delegate family gives us a lot of power to use generic delegates to make classes and algorithms more generic.  Using them keeps us from having to define a new delegate type when need to make a class or algorithm generic. Remember that the point of the Action delegate family was to be able to perform an “action” on an item, with no return results.  Thus Action delegates can be used to represent most methods that take 0 to 16 arguments but return void.  You can assign a method The Func delegate family was introduced in .NET 3.5 with the advent of LINQ, and gives us the power to define a function that can be called on 0 to 16 arguments and returns a result.  Thus, the main difference between Action and Func, from a delegate perspective, is that Actions return nothing, but Funcs return a result. The Func family of delegates have signatures as follows: Func<TResult> – matches a method that takes no arguments, and returns value of type TResult. Func<T, TResult> – matches a method that takes an argument of type T, and returns value of type TResult. Func<T1, T2, TResult> – matches a method that takes arguments of type T1 and T2, and returns value of type TResult. Func<T1, T2, …, TResult> – and so on up to 16 arguments, and returns value of type TResult. These are handy because they quickly allow you to be able to specify that a method or class you design will perform a function to produce a result as long as the method you specify meets the signature. For example, let’s say you were designing a generic aggregator, and you wanted to allow the user to define how the values will be aggregated into the result (i.e. Sum, Min, Max, etc…).  To do this, we would ask the user of our class to pass in a method that would take the current total, the next value, and produce a new total.  A class like this could look like: 1: public sealed class Aggregator<TValue, TResult> 2: { 3: // holds method that takes previous result, combines with next value, creates new result 4: private Func<TResult, TValue, TResult> _aggregationMethod; 5:  6: // gets or sets the current result of aggregation 7: public TResult Result { get; private set; } 8:  9: // construct the aggregator given the method to use to aggregate values 10: public Aggregator(Func<TResult, TValue, TResult> aggregationMethod = null) 11: { 12: if (aggregationMethod == null) throw new ArgumentNullException("aggregationMethod"); 13:  14: _aggregationMethod = aggregationMethod; 15: } 16:  17: // method to add next value 18: public void Aggregate(TValue nextValue) 19: { 20: // performs the aggregation method function on the current result and next and sets to current result 21: Result = _aggregationMethod(Result, nextValue); 22: } 23: } Of course, LINQ already has an Aggregate extension method, but that works on a sequence of IEnumerable<T>, whereas this is designed to work more with aggregating single results over time (such as keeping track of a max response time for a service). We could then use this generic aggregator to find the sum of a series of values over time, or the max of a series of values over time (among other things): 1: // creates an aggregator that adds the next to the total to sum the values 2: var sumAggregator = new Aggregator<int, int>((total, next) => total + next); 3:  4: // creates an aggregator (using static method) that returns the max of previous result and next 5: var maxAggregator = new Aggregator<int, int>(Math.Max); So, if we were timing the response time of a web method every time it was called, we could pass that response time to both of these aggregators to get an idea of the total time spent in that web method, and the max time spent in any one call to the web method: 1: // total will be 13 and max 13 2: int responseTime = 13; 3: sumAggregator.Aggregate(responseTime); 4: maxAggregator.Aggregate(responseTime); 5:  6: // total will be 20 and max still 13 7: responseTime = 7; 8: sumAggregator.Aggregate(responseTime); 9: maxAggregator.Aggregate(responseTime); 10:  11: // total will be 40 and max now 20 12: responseTime = 20; 13: sumAggregator.Aggregate(responseTime); 14: maxAggregator.Aggregate(responseTime); The Func delegate family is useful for making generic algorithms and classes, and in particular allows the caller of the method or user of the class to specify a function to be performed in order to generate a result. What is the result of a Func delegate chain? If you remember, we said earlier that you can assign multiple methods to a delegate by using the += operator to chain them.  So how does this affect delegates such as Func that return a value, when applied to something like the code below? 1: Func<int, int, int> combo = null; 2:  3: // What if we wanted to aggregate the sum and max together? 4: combo += (total, next) => total + next; 5: combo += Math.Max; 6:  7: // what is the result? 8: var comboAggregator = new Aggregator<int, int>(combo); Well, in .NET if you chain multiple methods in a delegate, they will all get invoked, but the result of the delegate is the result of the last method invoked in the chain.  Thus, this aggregator would always result in the Math.Max() result.  The other chained method (the sum) gets executed first, but it’s result is thrown away: 1: // result is 13 2: int responseTime = 13; 3: comboAggregator.Aggregate(responseTime); 4:  5: // result is still 13 6: responseTime = 7; 7: comboAggregator.Aggregate(responseTime); 8:  9: // result is now 20 10: responseTime = 20; 11: comboAggregator.Aggregate(responseTime); So remember, you can chain multiple Func (or other delegates that return values) together, but if you do so you will only get the last executed result. Func delegates and co-variance/contra-variance in .NET 4.0 Just like the Action delegate, as of .NET 4.0, the Func delegate family is contra-variant on its arguments.  In addition, it is co-variant on its return type.  To support this, in .NET 4.0 the signatures of the Func delegates changed to: Func<out TResult> – matches a method that takes no arguments, and returns value of type TResult (or a more derived type). Func<in T, out TResult> – matches a method that takes an argument of type T (or a less derived type), and returns value of type TResult(or a more derived type). Func<in T1, in T2, out TResult> – matches a method that takes arguments of type T1 and T2 (or less derived types), and returns value of type TResult (or a more derived type). Func<in T1, in T2, …, out TResult> – and so on up to 16 arguments, and returns value of type TResult (or a more derived type). Notice the addition of the in and out keywords before each of the generic type placeholders.  As we saw last week, the in keyword is used to specify that a generic type can be contra-variant -- it can match the given type or a type that is less derived.  However, the out keyword, is used to specify that a generic type can be co-variant -- it can match the given type or a type that is more derived. On contra-variance, if you are saying you need an function that will accept a string, you can just as easily give it an function that accepts an object.  In other words, if you say “give me an function that will process dogs”, I could pass you a method that will process any animal, because all dogs are animals.  On the co-variance side, if you are saying you need a function that returns an object, you can just as easily pass it a function that returns a string because any string returned from the given method can be accepted by a delegate expecting an object result, since string is more derived.  Once again, in other words, if you say “give me a method that creates an animal”, I can pass you a method that will create a dog, because all dogs are animals. It really all makes sense, you can pass a more specific thing to a less specific parameter, and you can return a more specific thing as a less specific result.  In other words, pay attention to the direction the item travels (parameters go in, results come out).  Keeping that in mind, you can always pass more specific things in and return more specific things out. For example, in the code below, we have a method that takes a Func<object> to generate an object, but we can pass it a Func<string> because the return type of object can obviously accept a return value of string as well: 1: // since Func<object> is co-variant, this will access Func<string>, etc... 2: public static string Sequence(int count, Func<object> generator) 3: { 4: var builder = new StringBuilder(); 5:  6: for (int i=0; i<count; i++) 7: { 8: object value = generator(); 9: builder.Append(value); 10: } 11:  12: return builder.ToString(); 13: } Even though the method above takes a Func<object>, we can pass a Func<string> because the TResult type placeholder is co-variant and accepts types that are more derived as well: 1: // delegate that's typed to return string. 2: Func<string> stringGenerator = () => DateTime.Now.ToString(); 3:  4: // This will work in .NET 4.0, but not in previous versions 5: Sequence(100, stringGenerator); Previous versions of .NET implemented some forms of co-variance and contra-variance before, but .NET 4.0 goes one step further and allows you to pass or assign an Func<A, BResult> to a Func<Y, ZResult> as long as A is less derived (or same) as Y, and BResult is more derived (or same) as ZResult. Sidebar: The Func and the Predicate A method that takes one argument and returns a bool is generally thought of as a predicate.  Predicates are used to examine an item and determine whether that item satisfies a particular condition.  Predicates are typically unary, but you may also have binary and other predicates as well. Predicates are often used to filter results, such as in the LINQ Where() extension method: 1: var numbers = new[] { 1, 2, 4, 13, 8, 10, 27 }; 2:  3: // call Where() using a predicate which determines if the number is even 4: var evens = numbers.Where(num => num % 2 == 0); As of .NET 3.5, predicates are typically represented as Func<T, bool> where T is the type of the item to examine.  Previous to .NET 3.5, there was a Predicate<T> type that tended to be used (which we’ll discuss next week) and is still supported, but most developers recommend using Func<T, bool> now, as it prevents confusion with overloads that accept unary predicates and binary predicates, etc.: 1: // this seems more confusing as an overload set, because of Predicate vs Func 2: public static SomeMethod(Predicate<int> unaryPredicate) { } 3: public static SomeMethod(Func<int, int, bool> binaryPredicate) { } 4:  5: // this seems more consistent as an overload set, since just uses Func 6: public static SomeMethod(Func<int, bool> unaryPredicate) { } 7: public static SomeMethod(Func<int, int, bool> binaryPredicate) { } Also, even though Predicate<T> and Func<T, bool> match the same signatures, they are separate types!  Thus you cannot assign a Predicate<T> instance to a Func<T, bool> instance and vice versa: 1: // the same method, lambda expression, etc can be assigned to both 2: Predicate<int> isEven = i => (i % 2) == 0; 3: Func<int, bool> alsoIsEven = i => (i % 2) == 0; 4:  5: // but the delegate instances cannot be directly assigned, strongly typed! 6: // ERROR: cannot convert type... 7: isEven = alsoIsEven; 8:  9: // however, you can assign by wrapping in a new instance: 10: isEven = new Predicate<int>(alsoIsEven); 11: alsoIsEven = new Func<int, bool>(isEven); So, the general advice that seems to come from most developers is that Predicate<T> is still supported, but we should use Func<T, bool> for consistency in .NET 3.5 and above. Sidebar: Func as a Generator for Unit Testing One area of difficulty in unit testing can be unit testing code that is based on time of day.  We’d still want to unit test our code to make sure the logic is accurate, but we don’t want the results of our unit tests to be dependent on the time they are run. One way (of many) around this is to create an internal generator that will produce the “current” time of day.  This would default to returning result from DateTime.Now (or some other method), but we could inject specific times for our unit testing.  Generators are typically methods that return (generate) a value for use in a class/method. For example, say we are creating a CacheItem<T> class that represents an item in the cache, and we want to make sure the item shows as expired if the age is more than 30 seconds.  Such a class could look like: 1: // responsible for maintaining an item of type T in the cache 2: public sealed class CacheItem<T> 3: { 4: // helper method that returns the current time 5: private static Func<DateTime> _timeGenerator = () => DateTime.Now; 6:  7: // allows internal access to the time generator 8: internal static Func<DateTime> TimeGenerator 9: { 10: get { return _timeGenerator; } 11: set { _timeGenerator = value; } 12: } 13:  14: // time the item was cached 15: public DateTime CachedTime { get; private set; } 16:  17: // the item cached 18: public T Value { get; private set; } 19:  20: // item is expired if older than 30 seconds 21: public bool IsExpired 22: { 23: get { return _timeGenerator() - CachedTime > TimeSpan.FromSeconds(30.0); } 24: } 25:  26: // creates the new cached item, setting cached time to "current" time 27: public CacheItem(T value) 28: { 29: Value = value; 30: CachedTime = _timeGenerator(); 31: } 32: } Then, we can use this construct to unit test our CacheItem<T> without any time dependencies: 1: var baseTime = DateTime.Now; 2:  3: // start with current time stored above (so doesn't drift) 4: CacheItem<int>.TimeGenerator = () => baseTime; 5:  6: var target = new CacheItem<int>(13); 7:  8: // now add 15 seconds, should still be non-expired 9: CacheItem<int>.TimeGenerator = () => baseTime.AddSeconds(15); 10:  11: Assert.IsFalse(target.IsExpired); 12:  13: // now add 31 seconds, should now be expired 14: CacheItem<int>.TimeGenerator = () => baseTime.AddSeconds(31); 15:  16: Assert.IsTrue(target.IsExpired); Now we can unit test for 1 second before, 1 second after, 1 millisecond before, 1 day after, etc.  Func delegates can be a handy tool for this type of value generation to support more testable code.  Summary Generic delegates give us a lot of power to make truly generic algorithms and classes.  The Func family of delegates is a great way to be able to specify functions to calculate a result based on 0-16 arguments.  Stay tuned in the weeks that follow for other generic delegates in the .NET Framework!   Tweet Technorati Tags: .NET, C#, CSharp, Little Wonders, Generics, Func, Delegates

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• Is there a version of the Arial or Tahoma font with monospaced digits and spaces?

  - by rossmcm

  The digits in the Arial font supplied with Windows are monospaced, in that they each take up the same horizontal space, but they seem to have neglected to provide a "monospaced" version of the space character. This means that you can't format a column of digits right-justified in (say) 12 spaces and have the right-hand edge be aligned. For example: 1 12 123 1234 12345 1234567 12345678 123456789 1234567890 works because the font used for code examples has spaces the same width as digits. This however doesn't work if the same text is displayed in Arial (I can't demonstrate because I can't figure out how to defeat SU's reformatting at the moment!). It just so happens that with Tahoma 8 point you can cheat because a space is exactly half the number of pixels as a digit, but that is messy and very specific.

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