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Is ADO.NET Entity framework database schema update possible?

- by fyasar

I'm working on proof of concept application like crm and i need your some advice. My application's data layer completely dynamic and run onto EF 3.5. When the user update the entity, change relation or add new column to the database, first i'm planning make for these with custom classes. After I rebuild my database model layer with new changes during the application runtime. And my model layer tie with tightly coupled to my project for easy reflecting model layer changes (It connected to my project via interfaces and loading onto to application domain in the runtime). I need to create dynamic entities, create entity relations and modify them during the runtime after that i need to create change database script for updating database schema. I know ADO.NET team says "we will be able to provide this property in EF 4.0", but i don't need to wait for them. How can i update database changes during the runtime via EF 3.5 ? For example, i need to create new entity or need to change some entity schema, add new properties or change property types after than how can apply these changes on the physical database schema ? Any ideas ?

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Velocity engine fails to load template from a remote shared folder

- by performanceuser

I have following code File temlateFile = new File( "D:/config/emails/MailBody.vm" ); temlateFile.exists(); VelocityEngine velocityEngine = new VelocityEngine(); velocityEngine.setProperty(RuntimeConstants.RESOURCE_LOADER, "file"); velocityEngine.setProperty("file.resource.loader.class", FileResourceLoader.class.getName()); velocityEngine.setProperty("file.resource.loader.path", temlateFile.getParentFile().getAbsolutePath()); velocityEngine.init(); template = velocityEngine.getTemplate( temlateFile.getName() ); This works because it is loading a file from local file system. Once I change the first like to: File temlateFile = new File( "//remote/config/emails/MailBody.vm" ); It doesn't work. org.apache.velocity.exception.ResourceNotFoundException: Unable to find resource 'MailBody.vm' at org.apache.velocity.runtime.resource.ResourceManagerImpl.loadResource(ResourceManagerImpl.java:474) at org.apache.velocity.runtime.resource.ResourceManagerImpl.getResource(ResourceManagerImpl.java:352) at org.apache.velocity.runtime.RuntimeInstance.getTemplate(RuntimeInstance.java:1533) at org.apache.velocity.runtime.RuntimeInstance.getTemplate(RuntimeInstance.java:1514) at org.apache.velocity.app.VelocityEngine.getTemplate(VelocityEngine.java:373) at com.actuate.iserver.mail.VelocityContent.<init>(VelocityContent.java:33) at com.actuate.iserver.mail.VolumeCreationMail.<init>(VolumeCreationMail.java:40) at com.actuate.iserver.mail.VolumeCreationMail.main(VolumeCreationMail.java:67) In both cases temlateFile.exists() always return true. Any ideas?

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C#/.NET Little Pitfalls: The Dangers of Casting Boxed Values

- by James Michael Hare

Starting a new series to parallel the Little Wonders series. In this series, I will examine some of the small pitfalls that can occasionally trip up developers. Introduction: Of Casts and Conversions What happens when we try to assign from an int and a double and vice-versa? 1: double pi = 3.14; 2: int theAnswer = 42; 3: 4: // implicit widening conversion, compiles! 5: double doubleAnswer = theAnswer; 6: 7: // implicit narrowing conversion, compiler error! 8: int intPi = pi; As you can see from the comments above, a conversion from a value type where there is no potential data loss is can be done with an implicit conversion. However, when converting from one value type to another may result in a loss of data, you must make the conversion explicit so the compiler knows you accept this risk. That is why the conversion from double to int will not compile with an implicit conversion, we can make the conversion explicit by adding a cast: 1: // explicit narrowing conversion using a cast, compiler 2: // succeeds, but results may have data loss: 3: int intPi = (int)pi; So for value types, the conversions (implicit and explicit) both convert the original value to a new value of the given type. With widening and narrowing references, however, this is not the case. Converting reference types is a bit different from converting value types. First of all when you perform a widening or narrowing you don’t really convert the instance of the object, you just convert the reference itself to the wider or narrower reference type, but both the original and new reference type both refer back to the same object. Secondly, widening and narrowing for reference types refers the going down and up the class hierarchy instead of referring to precision as in value types. That is, a narrowing conversion for a reference type means you are going down the class hierarchy (for example from Shape to Square) whereas a widening conversion means you are going up the class hierarchy (from Square to Shape). 1: var square = new Square(); 2: 3: // implicitly convers because all squares are shapes 4: // (that is, all subclasses can be referenced by a superclass reference) 5: Shape myShape = square; 6: 7: // implicit conversion not possible, not all shapes are squares! 8: // (that is, not all superclasses can be referenced by a subclass reference) 9: Square mySquare = (Square) myShape; So we had to cast the Shape back to Square because at that point the compiler has no way of knowing until runtime whether the Shape in question is truly a Square. But, because the compiler knows that it’s possible for a Shape to be a Square, it will compile. However, if the object referenced by myShape is not truly a Square at runtime, you will get an invalid cast exception. Of course, there are other forms of conversions as well such as user-specified conversions and helper class conversions which are beyond the scope of this post. The main thing we want to focus on is this seemingly innocuous casting method of widening and narrowing conversions that we come to depend on every day and, in some cases, can bite us if we don’t fully understand what is going on! The Pitfall: Conversions on Boxed Value Types Can Fail What if you saw the following code and – knowing nothing else – you were asked if it was legal or not, what would you think: 1: // assuming x is defined above this and this 2: // assignment is syntactically legal. 3: x = 3.14; 4: 5: // convert 3.14 to int. 6: int truncated = (int)x; You may think that since x is obviously a double (can’t be a float) because 3.14 is a double literal, but this is inaccurate. Our x could also be dynamic and this would work as well, or there could be user-defined conversions in play. But there is another, even simpler option that can often bite us: what if x is object? 1: object x; 2: 3: x = 3.14; 4: 5: int truncated = (int) x; On the surface, this seems fine. We have a double and we place it into an object which can be done implicitly through boxing (no cast) because all types inherit from object. Then we cast it to int. This theoretically should be possible because we know we can explicitly convert a double to an int through a conversion process which involves truncation. But here’s the pitfall: when casting an object to another type, we are casting a reference type, not a value type! This means that it will attempt to see at runtime if the value boxed and referred to by x is of type int or derived from type int. Since it obviously isn’t (it’s a double after all) we get an invalid cast exception! Now, you may say this looks awfully contrived, but in truth we can run into this a lot if we’re not careful. Consider using an IDataReader to read from a database, and then attempting to select a result row of a particular column type: 1: using (var connection = new SqlConnection("some connection string")) 2: using (var command = new SqlCommand("select * from employee", connection)) 3: using (var reader = command.ExecuteReader()) 4: { 5: while (reader.Read()) 6: { 7: // if the salary is not an int32 in the SQL database, this is an error! 8: // doesn't matter if short, long, double, float, reader [] returns object! 9: total += (int) reader["annual_salary"]; 10: } 11: } Notice that since the reader indexer returns object, if we attempt to convert using a cast to a type, we have to make darn sure we use the true, actual type or this will fail! If the SQL database column is a double, float, short, etc this will fail at runtime with an invalid cast exception because it attempts to convert the object reference! So, how do you get around this? There are two ways, you could first cast the object to its actual type (double), and then do a narrowing cast to on the value to int. Or you could use a helper class like Convert which analyzes the actual run-time type and will perform a conversion as long as the type implements IConvertible. 1: object x; 2: 3: x = 3.14; 4: 5: // if you want to cast, must cast out of object to double, then 6: // cast convert. 7: int truncated = (int)(double) x; 8: 9: // or you can call a helper class like Convert which examines runtime 10: // type of the value being converted 11: int anotherTruncated = Convert.ToInt32(x); Summary You should always be careful when performing a conversion cast from values boxed in object that you are actually casting to the true type (or a sub-type). Since casting from object is a widening of the reference, be careful that you either know the exact, explicit type you expect to be held in the object, or instead avoid the cast and use a helper class to perform a safe conversion to the type you desire. Technorati Tags: C#,.NET,Pitfalls,Little Pitfalls,BlackRabbitCoder

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RequestValidation Changes in ASP.NET 4.0

- by Rick Strahl

There’s been a change in the way the ValidateRequest attribute on WebForms works in ASP.NET 4.0. I noticed this today while updating a post on my WebLog all of which contain raw HTML and so all pretty much trigger request validation. I recently upgraded this app from ASP.NET 2.0 to 4.0 and it’s now failing to update posts. At first this was difficult to track down because of custom error handling in my app – the custom error handler traps the exception and logs it with only basic error information so the full detail of the error was initially hidden. After some more experimentation in development mode the error that occurs is the typical ASP.NET validate request error (‘A potentially dangerous Request.Form value was detetected…’) which looks like this in ASP.NET 4.0: At first when I got this I was real perplexed as I didn’t read the entire error message and because my page does have: <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="NewEntry.aspx.cs" Inherits="Westwind.WebLog.NewEntry" MasterPageFile="~/App_Templates/Standard/AdminMaster.master" ValidateRequest="false" EnableEventValidation="false" EnableViewState="false" %> WTF? ValidateRequest would seem like it should be enough, but alas in ASP.NET 4.0 apparently that setting alone is no longer enough. Reading the fine print in the error explains that you need to explicitly set the requestValidationMode for the application back to V2.0 in web.config: <httpRuntime executionTimeout="300" requestValidationMode="2.0" /> Kudos for the ASP.NET team for putting up a nice error message that tells me how to fix this problem, but excuse me why the heck would you change this behavior to require an explicit override to an optional and by default disabled page level switch? You’ve just made a relatively simple fix to a solution a nasty morass of hard to discover configuration settings??? The original way this worked was perfectly discoverable via attributes in the page. Now you can set this setting in the page and get completely unexpected behavior and you are required to set what effectively amounts to a backwards compatibility flag in the configuration file. It turns out the real reason for the .config flag is that the request validation behavior has moved from WebForms pipeline down into the entire ASP.NET/IIS request pipeline and is now applied against all requests. Here’s what the breaking changes page from Microsoft says about it: The request validation feature in ASP.NET provides a certain level of default protection against cross-site scripting (XSS) attacks. In previous versions of ASP.NET, request validation was enabled by default. However, it applied only to ASP.NET pages (.aspx files and their class files) and only when those pages were executing. 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. As a result, request validation errors might now occur for requests that previously did not trigger errors. To revert to the behavior of the ASP.NET 2.0 request validation feature, add the following setting in the Web.config file: <httpRuntime requestValidationMode="2.0" /> However, we recommend that you analyze any request validation errors to determine whether existing handlers, modules, or other custom code accesses potentially unsafe HTTP inputs that could be XSS attack vectors. Ok, so ValidateRequest of the form still works as it always has but it’s actually the ASP.NET Event Pipeline, not WebForms that’s throwing the above exception as request validation is applied to every request that hits the pipeline. Creating the runtime override removes the HttpRuntime checking and restores the WebForms only behavior. That fixes my immediate problem but still leaves me wondering especially given the vague wording of the above explanation. One thing that’s missing in the description is above is one important detail: The request validation is applied only to application/x-www-form-urlencoded POST content not to all inbound POST data. When I first read this this freaked me out because it sounds like literally ANY request hitting the pipeline is affected. To make sure this is not really so I created a quick handler: public class Handler1 : IHttpHandler { public void ProcessRequest(HttpContext context) { context.Response.ContentType = "text/plain"; context.Response.Write("Hello World <hr>" + context.Request.Form.ToString()); } public bool IsReusable { get { return false; } } } and called it with Fiddler by posting some XML to the handler using a default form-urlencoded POST content type: and sure enough – hitting the handler also causes the request validation error and 500 server response. Changing the content type to text/xml effectively fixes the problem however, bypassing the request validation filter so Web Services/AJAX handlers and custom modules/handlers that implement custom protocols aren’t affected as long as they work with special input content types. It also looks that multipart encoding does not trigger event validation of the runtime either so this request also works fine: POST http://rasnote/weblog/handler1.ashx HTTP/1.1 Content-Type: multipart/form-data; boundary=------7cf2a327f01ae User-Agent: West Wind Internet Protocols 5.53 Host: rasnote Content-Length: 40 Pragma: no-cache <xml>asdasd</xml>--------7cf2a327f01ae *That* probably should trigger event validation – since it is a potential HTML form submission, but it doesn’t. New Runtime Feature, Global Scope Only? Ok, so request validation is now a runtime feature but sadly it’s a feature that’s scoped to the ASP.NET Runtime – effective scope to the entire running application/app domain. You can still manually force validation using Request.ValidateInput() which gives you the option to do this in code, but that realistically will only work with the requestValidationMode set to V2.0 as well since the 4.0 mode auto-fires before code ever gets a chance to intercept the call. Given all that, the new setting in ASP.NET 4.0 seems to limit options and makes things more difficult and less flexible. Of course Microsoft gets to say ASP.NET is more secure by default because of it but what good is that if you have to turn off this flag the very first time you need to allow one single request that bypasses request validation??? This is really shortsighted design… <sigh>© Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET

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A simple Dynamic Proxy

- by Abhijeet Patel

Frameworks such as EF4 and MOQ do what most developers consider "dark magic". For instance in EF4, when you use a POCO for an entity you can opt-in to get behaviors such as "lazy-loading" and "change tracking" at runtime merely by ensuring that your type has the following characteristics: The class must be public and not sealed. The class must have a public or protected parameter-less constructor. The class must have public or protected properties Adhere to this and your type is magically endowed with these behaviors without any additional programming on your part. Behind the scenes the framework subclasses your type at runtime and creates a "dynamic proxy" which has these additional behaviors and when you navigate properties of your POCO, the framework replaces the POCO type with derived type instances. The MOQ framework does simlar magic. Let's say you have a simple interface: public interface IFoo { int GetNum(); } We can verify that the GetNum() was invoked on a mock like so: var mock = new Mock<IFoo>(MockBehavior.Default); mock.Setup(f => f.GetNum()); var num = mock.Object.GetNum(); mock.Verify(f => f.GetNum()); Beind the scenes the MOQ framework is generating a dynamic proxy by implementing IFoo at runtime. the call to moq.Object returns the dynamic proxy on which we then call "GetNum" and then verify that this method was invoked. No dark magic at all, just clever programming is what's going on here, just not visible and hence appears magical! Let's create a simple dynamic proxy generator which accepts an interface type and dynamically creates a proxy implementing the interface type specified at runtime. public static class DynamicProxyGenerator { public static T GetInstanceFor<T>() { Type typeOfT = typeof(T); var methodInfos = typeOfT.GetMethods(); AssemblyName assName = new AssemblyName("testAssembly"); var assBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(assName, AssemblyBuilderAccess.RunAndSave); var moduleBuilder = assBuilder.DefineDynamicModule("testModule", "test.dll"); var typeBuilder = moduleBuilder.DefineType(typeOfT.Name + "Proxy", TypeAttributes.Public); typeBuilder.AddInterfaceImplementation(typeOfT); var ctorBuilder = typeBuilder.DefineConstructor( MethodAttributes.Public, CallingConventions.Standard, new Type[] { }); var ilGenerator = ctorBuilder.GetILGenerator(); ilGenerator.EmitWriteLine("Creating Proxy instance"); ilGenerator.Emit(OpCodes.Ret); foreach (var methodInfo in methodInfos) { var methodBuilder = typeBuilder.DefineMethod( methodInfo.Name, MethodAttributes.Public | MethodAttributes.Virtual, methodInfo.ReturnType, methodInfo.GetParameters().Select(p => p.GetType()).ToArray() ); var methodILGen = methodBuilder.GetILGenerator(); methodILGen.EmitWriteLine("I'm a proxy"); if (methodInfo.ReturnType == typeof(void)) { methodILGen.Emit(OpCodes.Ret); } else { if (methodInfo.ReturnType.IsValueType || methodInfo.ReturnType.IsEnum) { MethodInfo getMethod = typeof(Activator).GetMethod(/span>"CreateInstance",new Type[]{typeof((Type)}); LocalBuilder lb = methodILGen.DeclareLocal(methodInfo.ReturnType); methodILGen.Emit(OpCodes.Ldtoken, lb.LocalType); methodILGen.Emit(OpCodes.Call, typeofype).GetMethod("GetTypeFromHandle")); )); methodILGen.Emit(OpCodes.Callvirt, getMethod); methodILGen.Emit(OpCodes.Unbox_Any, lb.LocalType); } else { methodILGen.Emit(OpCodes.Ldnull); } methodILGen.Emit(OpCodes.Ret); } typeBuilder.DefineMethodOverride(methodBuilder, methodInfo); } Type constructedType = typeBuilder.CreateType(); var instance = Activator.CreateInstance(constructedType); return (T)instance; } } Dynamic proxies are created by calling into the following main types: AssemblyBuilder, TypeBuilder, Modulebuilder and ILGenerator. These types enable dynamically creating an assembly and emitting .NET modules and types in that assembly, all using IL instructions. Let's break down the code above a bit and examine it piece by piece Type typeOfT = typeof(T); var methodInfos = typeOfT.GetMethods(); AssemblyName assName = new AssemblyName("testAssembly"); var assBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(assName, AssemblyBuilderAccess.RunAndSave); var moduleBuilder = assBuilder.DefineDynamicModule("testModule", "test.dll"); var typeBuilder = moduleBuilder.DefineType(typeOfT.Name + "Proxy", TypeAttributes.Public); We are instructing the runtime to create an assembly caled "test.dll"and in this assembly we then emit a new module called "testModule". We then emit a new type definition of name "typeName"Proxy into this new module. This is the definition for the "dynamic proxy" for type T typeBuilder.AddInterfaceImplementation(typeOfT); var ctorBuilder = typeBuilder.DefineConstructor( MethodAttributes.Public, CallingConventions.Standard, new Type[] { }); var ilGenerator = ctorBuilder.GetILGenerator(); ilGenerator.EmitWriteLine("Creating Proxy instance"); ilGenerator.Emit(OpCodes.Ret); The newly created type implements type T and defines a default parameterless constructor in which we emit a call to Console.WriteLine. This call is not necessary but we do this so that we can see first hand that when the proxy is constructed, when our default constructor is invoked. var methodBuilder = typeBuilder.DefineMethod( methodInfo.Name, MethodAttributes.Public | MethodAttributes.Virtual, methodInfo.ReturnType, methodInfo.GetParameters().Select(p => p.GetType()).ToArray() ); We then iterate over each method declared on type T and add a method definition of the same name into our "dynamic proxy" definition if (methodInfo.ReturnType == typeof(void)) { methodILGen.Emit(OpCodes.Ret); } If the return type specified in the method declaration of T is void we simply return. if (methodInfo.ReturnType.IsValueType || methodInfo.ReturnType.IsEnum) { MethodInfo getMethod = typeof(Activator).GetMethod("CreateInstance", new Type[]{typeof(Type)}); LocalBuilder lb = methodILGen.DeclareLocal(methodInfo.ReturnType); methodILGen.Emit(OpCodes.Ldtoken, lb.LocalType); methodILGen.Emit(OpCodes.Call, typeof(Type).GetMethod("GetTypeFromHandle")); methodILGen.Emit(OpCodes.Callvirt, getMethod); methodILGen.Emit(OpCodes.Unbox_Any, lb.LocalType); } If the return type in the method declaration of T is either a value type or an enum, then we need to create an instance of the value type and return that instance the caller. In order to accomplish that we need to do the following: 1) Get a handle to the Activator.CreateInstance method 2) Declare a local variable which represents the Type of the return type(i.e the type object of the return type) specified on the method declaration of T(obtained from the MethodInfo) and push this Type object onto the evaluation stack. In reality a RuntimeTypeHandle is what is pushed onto the stack. 3) Invoke the "GetTypeFromHandle" method(a static method in the Type class) passing in the RuntimeTypeHandle pushed onto the stack previously as an argument, the result of this invocation is a Type object (representing the method's return type) which is pushed onto the top of the evaluation stack. 4) Invoke Activator.CreateInstance passing in the Type object from step 3, the result of this invocation is an instance of the value type boxed as a reference type and pushed onto the top of the evaluation stack. 5) Unbox the result and place it into the local variable of the return type defined in step 2 methodILGen.Emit(OpCodes.Ldnull); If the return type is a reference type then we just load a null onto the evaluation stack methodILGen.Emit(OpCodes.Ret); Emit a a return statement to return whatever is on top of the evaluation stack(null or an instance of a value type) back to the caller Type constructedType = typeBuilder.CreateType(); var instance = Activator.CreateInstance(constructedType); return (T)instance; Now that we have a definition of the "dynamic proxy" implementing all the methods declared on T, we can now create an instance of the proxy type and return that out typed as T. The caller can now invoke the generator and request a dynamic proxy for any type T. In our example when the client invokes GetNum() we get back "0". Lets add a new method on the interface called DayOfWeek GetDay() public interface IFoo { int GetNum(); DayOfWeek GetDay(); } When GetDay() is invoked, the "dynamic proxy" returns "Sunday" since that is the default value for the DayOfWeek enum This is a very trivial example of dynammic proxies, frameworks like MOQ have a way more sophisticated implementation of this paradigm where in you can instruct the framework to create proxies which return specified values for a method implementation.

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Nashorn, the rhino in the room

- by costlow

Nashorn is a new runtime within JDK 8 that allows developers to run code written in JavaScript and call back and forth with Java. One advantage to the Nashorn scripting engine is that is allows for quick prototyping of functionality or basic shell scripts that use Java libraries. The previous JavaScript runtime, named Rhino, was introduced in JDK 6 (released 2006, end of public updates Feb 2013). Keeping tradition amongst the global developer community, "Nashorn" is the German word for rhino. The Java platform and runtime is an intentional home to many languages beyond the Java language itself. OpenJDK’s Da Vinci Machine helps coordinate work amongst language developers and tool designers and has helped different languages by introducing the Invoke Dynamic instruction in Java 7 (2011), which resulted in two major benefits: speeding up execution of dynamic code, and providing the groundwork for Java 8’s lambda executions. Many of these improvements are discussed at the JVM Language Summit, where language and tool designers get together to discuss experiences and issues related to building these complex components. There are a number of benefits to running JavaScript applications on JDK 8’s Nashorn technology beyond writing scripts quickly: Interoperability with Java and JavaScript libraries. Scripts do not need to be compiled. Fast execution and multi-threading of JavaScript running in Java’s JRE. The ability to remotely debug applications using an IDE like NetBeans, Eclipse, or IntelliJ (instructions on the Nashorn blog). Automatic integration with Java monitoring tools, such as performance, health, and SIEM. In the remainder of this blog post, I will explain how to use Nashorn and the benefit from those features. Nashorn execution environment The Nashorn scripting engine is included in all versions of Java SE 8, both the JDK and the JRE. Unlike Java code, scripts written in nashorn are interpreted and do not need to be compiled before execution. Developers and users can access it in two ways: Users running JavaScript applications can call the binary directly:jre8/bin/jjs This mechanism can also be used in shell scripts by specifying a shebang like #!/usr/bin/jjs Developers can use the API and obtain a ScriptEngine through:ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn"); When using a ScriptEngine, please understand that they execute code. Avoid running untrusted scripts or passing in untrusted/unvalidated inputs. During compilation, consider isolating access to the ScriptEngine and using Type Annotations to only allow @Untainted String arguments. One noteworthy difference between JavaScript executed in or outside of a web browser is that certain objects will not be available. For example when run outside a browser, there is no access to a document object or DOM tree. Other than that, all syntax, semantics, and capabilities are present. Examples of Java and JavaScript The Nashorn script engine allows developers of all experience levels the ability to write and run code that takes advantage of both languages. The specific dialect is ECMAScript 5.1 as identified by the User Guide and its standards definition through ECMA international. In addition to the example below, Benjamin Winterberg has a very well written Java 8 Nashorn Tutorial that provides a large number of code samples in both languages. Basic Operations A basic Hello World application written to run on Nashorn would look like this: #!/usr/bin/jjs print("Hello World"); The first line is a standard script indication, so that Linux or Unix systems can run the script through Nashorn. On Windows where scripts are not as common, you would run the script like: jjs helloWorld.js. Receiving Arguments In order to receive program arguments your jjs invocation needs to use the -scripting flag and a double-dash to separate which arguments are for jjs and which are for the script itself:jjs -scripting print.js -- "This will print" #!/usr/bin/jjs var whatYouSaid = $ARG.length==0 ? "You did not say anything" : $ARG[0] print(whatYouSaid); Interoperability with Java libraries (including 3rd party dependencies) Another goal of Nashorn was to allow for quick scriptable prototypes, allowing access into Java types and any libraries. Resources operate in the context of the script (either in-line with the script or as separate threads) so if you open network sockets and your script terminates, those sockets will be released and available for your next run. Your code can access Java types the same as regular Java classes. The “import statements” are written somewhat differently to accommodate for language. There is a choice of two styles: For standard classes, just name the class: var ServerSocket = java.net.ServerSocket For arrays or other items, use Java.type: var ByteArray = Java.type("byte[]")You could technically do this for all. The same technique will allow your script to use Java types from any library or 3rd party component and quickly prototype items. Building a user interface One major difference between JavaScript inside and outside of a web browser is the availability of a DOM object for rendering views. When run outside of the browser, JavaScript has full control to construct the entire user interface with pre-fabricated UI controls, charts, or components. The example below is a variation from the Nashorn and JavaFX guide to show how items work together. Nashorn has a -fx flag to make the user interface components available. With the example script below, just specify: jjs -fx -scripting fx.js -- "My title" #!/usr/bin/jjs -fx var Button = javafx.scene.control.Button; var StackPane = javafx.scene.layout.StackPane; var Scene = javafx.scene.Scene; var clickCounter=0; $STAGE.title = $ARG.length>0 ? $ARG[0] : "You didn't provide a title"; var button = new Button(); button.text = "Say 'Hello World'"; button.onAction = myFunctionForButtonClicking; var root = new StackPane(); root.children.add(button); $STAGE.scene = new Scene(root, 300, 250); $STAGE.show(); function myFunctionForButtonClicking(){ var text = "Click Counter: " + clickCounter; button.setText(text); clickCounter++; print(text); } For a more advanced post on using Nashorn to build a high-performing UI, see JavaFX with Nashorn Canvas example. Interoperable with frameworks like Node, Backbone, or Facebook React The major benefit of any language is the interoperability gained by people and systems that can read, write, and use it for interactions. Because Nashorn is built for the ECMAScript specification, developers familiar with JavaScript frameworks can write their code and then have system administrators deploy and monitor the applications the same as any other Java application. A number of projects are also running Node applications on Nashorn through Project Avatar and the supported modules. In addition to the previously mentioned Nashorn tutorial, Benjamin has also written a post about Using Backbone.js with Nashorn. To show the multi-language power of the Java Runtime, there is another interesting example that unites Facebook React and Clojure on JDK 8’s Nashorn. Summary Nashorn provides a simple and fast way of executing JavaScript applications and bridging between the best of each language. By making the full range of Java libraries to JavaScript applications, and the quick prototyping style of JavaScript to Java applications, developers are free to work as they see fit. Software Architects and System Administrators can take advantage of one runtime and leverage any work that they have done to tune, monitor, and certify their systems. Additional information is available within: The Nashorn Users’ Guide Java Magazine’s article "Next Generation JavaScript Engine for the JVM." The Nashorn team’s primary blog or a very helpful collection of Nashorn links.

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elffile: ELF Specific File Identification Utility

- by user9154181

Solaris 11 has a new standard user level command, /usr/bin/elffile. elffile is a variant of the file utility that is focused exclusively on linker related files: ELF objects, archives, and runtime linker configuration files. All other files are simply identified as "non-ELF". The primary advantage of elffile over the existing file utility is in the area of archives — elffile examines the archive members and can produce a summary of the contents, or per-member details. The impetus to add elffile to Solaris came from the effort to extend the format of Solaris archives so that they could grow beyond their previous 32-bit file limits. That work introduced a new archive symbol table format. Now that there was more than one possible format, I thought it would be useful if the file utility could identify which format a given archive is using, leading me to extend the file utility: % cc -c ~/hello.c % ar r foo.a hello.o % file foo.a foo.a: current ar archive, 32-bit symbol table % ar r -S foo.a hello.o % file foo.a foo.a: current ar archive, 64-bit symbol table In turn, this caused me to think about all the things that I would like the file utility to be able to tell me about an archive. In particular, I'd like to be able to know what's inside without having to unpack it. The end result of that train of thought was elffile. Much of the discussion in this article is adapted from the PSARC case I filed for elffile in December 2010: PSARC 2010/432 elffile Why file Is No Good For Archives And Yet Should Not Be Fixed The standard /usr/bin/file utility is not very useful when applied to archives. When identifying an archive, a user typically wants to know 2 things: Is this an archive? Presupposing that the archive contains objects, which is by far the most common use for archives, what platform are the objects for? Are they for sparc or x86? 32 or 64-bit? Some confusing combination from varying platforms? The file utility provides a quick answer to question (1), as it identifies all archives as "current ar archive". It does nothing to answer the more interesting question (2). To answer that question, requires a multi-step process: Extract all archive members Use the file utility on the extracted files, examine the output for each file in turn, and compare the results to generate a suitable summary description. Remove the extracted files It should be easier and more efficient to answer such an obvious question. It would be reasonable to extend the file utility to examine archive contents in place and produce a description. However, there are several reasons why I decided not to do so: The correct design for this feature within the file utility would have file examine each archive member in turn, applying its full abilities to each member. This would be elegant, but also represents a rather dramatic redesign and re-implementation of file. Archives nearly always contain nothing but ELF objects for a single platform, so such generality in the file utility would be of little practical benefit. It is best to avoid adding new options to standard utilities for which other implementations of interest exist. In the case of the file utility, one concern is that we might add an option which later appears in the GNU version of file with a different and incompatible meaning. Indeed, there have been discussions about replacing the Solaris file with the GNU version in the past. This may or may not be desirable, and may or may not ever happen. Either way, I don't want to preclude it. Examining archive members is an O(n) operation, and can be relatively slow with large archives. The file utility is supposed to be a very fast operation. I decided that extending file in this way is overkill, and that an investment in the file utility for better archive support would not be worth the cost. A solution that is more narrowly focused on ELF and other linker related files is really all that we need. The necessary code for doing this already exists within libelf. All that is missing is a small user-level wrapper to make that functionality available at the command line. In that vein, I considered adding an option for this to the elfdump utility. I examined elfdump carefully, and even wrote a prototype implementation. The added code is small and simple, but the conceptual fit with the rest of elfdump is poor. The result complicates elfdump syntax and documentation, definite signs that this functionality does not belong there. And so, I added this functionality as a new user level command. The elffile Command The syntax for this new command is elffile [-s basic | detail | summary] filename... Please see the elffile(1) manpage for additional details. To demonstrate how output from elffile looks, I will use the following files: FileDescription configA runtime linker configuration file produced with crle dwarf.oAn ELF object /etc/passwdA text file mixed.aArchive containing a mixture of ELF and non-ELF members mixed_elf.aArchive containing ELF objects for different machines not_elf.aArchive containing no ELF objects same_elf.aArchive containing a collection of ELF objects for the same machine. This is the most common type of archive. The file utility identifies these files as follows: % file config dwarf.o /etc/passwd mixed.a mixed_elf.a not_elf.a same_elf.a config: Runtime Linking Configuration 64-bit MSB SPARCV9 dwarf.o: ELF 64-bit LSB relocatable AMD64 Version 1 /etc/passwd: ascii text mixed.a: current ar archive, 32-bit symbol table mixed_elf.a: current ar archive, 32-bit symbol table not_elf.a: current ar archive same_elf.a: current ar archive, 32-bit symbol table By default, elffile uses its "summary" output style. This output differs from the output from the file utility in 2 significant ways: Files that are not an ELF object, archive, or runtime linker configuration file are identified as "non-ELF", whereas the file utility attempts further identification for such files. When applied to an archive, the elffile output includes a description of the archive's contents, without requiring member extraction or other additional steps. Applying elffile to the above files: % elffile config dwarf.o /etc/passwd mixed.a mixed_elf.a not_elf.a same_elf.a config: Runtime Linking Configuration 64-bit MSB SPARCV9 dwarf.o: ELF 64-bit LSB relocatable AMD64 Version 1 /etc/passwd: non-ELF mixed.a: current ar archive, 32-bit symbol table, mixed ELF and non-ELF content mixed_elf.a: current ar archive, 32-bit symbol table, mixed ELF content not_elf.a: current ar archive, non-ELF content same_elf.a: current ar archive, 32-bit symbol table, ELF 64-bit LSB relocatable AMD64 Version 1 The output for same_elf.a is of particular interest: The vast majority of archives contain only ELF objects for a single platform, and in this case, the default output from elffile answers both of the questions about archives posed at the beginning of this discussion, in a single efficient step. This makes elffile considerably more useful than file, within the realm of linker-related files. elffile can produce output in two other styles, "basic", and "detail". The basic style produces output that is the same as that from 'file', for linker-related files. The detail style produces per-member identification of archive contents. This can be useful when the archive contents are not homogeneous ELF object, and more information is desired than the summary output provides: % elffile -s detail mixed.a mixed.a: current ar archive, 32-bit symbol table mixed.a(dwarf.o): ELF 32-bit LSB relocatable 80386 Version 1 mixed.a(main.c): non-ELF content mixed.a(main.o): ELF 64-bit LSB relocatable AMD64 Version 1 [SSE]

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Table comment length in mysql

- by azerole

According to MySQL manual, table comments are limited to 60 characters. I'm designing the schema in MySQL Workbench, which does not enforce this limit, so I end up with writing more than 60 symbols quite often, and this causes the SQL script to fail. To tell the truth I would be quite happy with table comments being internal to my schema (i.e. not exported to the actual database), but Workbench doesn't allow this either. Hence my question: is there a way to increase maximum length of table comment in MySQL to 255?

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Cannot Install JDK

- by Vince

For the life of me, I can't install the JDK on Windows Vista. I keep getting the error, "This Software Has Already Been Installed on Your Computer. Would you like to reinstall it?" Problem is, it's evidently not on my computer, since I can't a) run Eclipse - I get "Could Not Find Java SE Runtime Environment" or b) Find any reference to Java from the command line when typing java -version - I get "Error opening registry key 'Registry/JavaSoft/Java Runtime Environment." Any ideas?

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Uninstall Java on Mac OS X?

- by Jesse

I'm working on a trouble shooting document for some desktop software that runs in Java. One of the last resort steps is to completely uninstall and reinstall the Java runtime. In Windows XP this can be done via Add/Remove Programs. Is there something equivalent on OSX? Or does reinstalling the runtime overwrite the current version?

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Inheritance security rules violated while overriding member - SecurityRuleSet.Level2

- by Page Brooks

I have a class that inherits from Exception. In .NET 4, I started receiving a runtime error: Inheritance security rules violated while overriding member: MyBusinessException.GetObjectData(System.Runtime.Serialization.SerializationInfo, System.Runtime.Serialization.StreamingContext)'. Security accessibility of the overriding method must match the security accessibility of the method being overriden. I think the issue is caused by the fact that I am overriding GetObjectData. I know one answer for resolving the issue is to set the SecurityRuleSet: [assembly: SecurityRules(SecurityRuleSet.Level1)] This is not an acceptable answer, I'd like to know how to fix the issue without having to relax the default security rules in .NET 4.

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how to bind datasouce to the labels and pass parameter in XtraReport ?

- by ahmed

There's something that I don't get it yet in Xtrareport. I have to bind the datasource at runtime and also I have to assign the datasource to the labels programatically. Binding data at runtime is fine ,(and here's my question)I did not get from any examples to how should I bind the datasource to the labels and how to pass the parameter(UserId) from runtime and how to call the report from a webform. For example, I have a table called "User" with 3 fields: UserId, Username and Password. In the report designer I place 3 labels. Then I have a webform where the user is entering the userID and pulling some data and I have a print button on that webform when the user clicks the print button the data should be displayed on the report of UserId..

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Installing .NET 3.5 SP1 on server broke WCF

- by Doron

I installed .NET 3.5 SP1 on server which previously had .NET 3.0 SP2. Before install site was working perfectly. After install and subsequeny server restart, site displays but anything that makes use of the WCF service has stopped working. The exception log reports exceptions like the following when any calls are made to the client proxy: The communication object, System.ServiceModel.Channels.ServiceChannel, cannot be used for communication because it is in the Faulted state. The server's application event log gave the following errors after the install: Configuration section system.serviceModel.activation already exists in c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Config\machine.config. Configuration section system.runtime.serialization already exists in c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Config\machine.config. Configuration section system.serviceModel already exists in c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Config\machine.config. which seems to be inline with the fact that anything WCF related has stopped working. I am not experienced in server configurations or WCF so looking for any assistance with this. Thanks!! From machine.config: <sectionGroup name="system.serviceModel" type="System.ServiceModel.Configuration.ServiceModelSectionGroup, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"> <section name="behaviors" type="System.ServiceModel.Configuration.BehaviorsSection, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/> <section name="bindings" type="System.ServiceModel.Configuration.BindingsSection, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/> <section name="client" type="System.ServiceModel.Configuration.ClientSection, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/> <section name="comContracts" type="System.ServiceModel.Configuration.ComContractsSection, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/> <section name="commonBehaviors" type="System.ServiceModel.Configuration.CommonBehaviorsSection, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" allowDefinition="MachineOnly" allowExeDefinition="MachineOnly"/> <section name="diagnostics" type="System.ServiceModel.Configuration.DiagnosticSection, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/> <section name="extensions" type="System.ServiceModel.Configuration.ExtensionsSection, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/> <section name="machineSettings" type="System.ServiceModel.Configuration.MachineSettingsSection, SMDiagnostics, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" allowDefinition="MachineOnly" allowExeDefinition="MachineOnly"/> <section name="serviceHostingEnvironment" type="System.ServiceModel.Configuration.ServiceHostingEnvironmentSection, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/> <section name="services" type="System.ServiceModel.Configuration.ServicesSection, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/> </sectionGroup> <sectionGroup name="system.serviceModel.activation" type="System.ServiceModel.Activation.Configuration.ServiceModelActivationSectionGroup, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"> <section name="diagnostics" type="System.ServiceModel.Activation.Configuration.DiagnosticSection, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/> <section name="net.pipe" type="System.ServiceModel.Activation.Configuration.NetPipeSection, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/> <section name="net.tcp" type="System.ServiceModel.Activation.Configuration.NetTcpSection, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/> </sectionGroup> <sectionGroup name="system.runtime.serialization" type="System.Runtime.Serialization.Configuration.SerializationSectionGroup, System.Runtime.Serialization, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"> <section name="dataContractSerializer" type="System.Runtime.Serialization.Configuration.DataContractSerializerSection, System.Runtime.Serialization, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/> </sectionGroup> from site's web.config <sectionGroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"> <sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"> <section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" /> <sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"> <section name="jsonSerialization" type="System.Web.Configuration.ScriptingJsonSerializationSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="Everywhere" /> <section name="profileService" type="System.Web.Configuration.ScriptingProfileServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" /> <section name="authenticationService" type="System.Web.Configuration.ScriptingAuthenticationServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" /> <section name="roleService" type="System.Web.Configuration.ScriptingRoleServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" /> </sectionGroup> </sectionGroup> </sectionGroup> . . . <system.serviceModel> <bindings> <wsHttpBinding> <binding name="WSHttpBinding_IService" closeTimeout="00:03:00" openTimeout="00:03:00" receiveTimeout="00:10:00" sendTimeout="00:03:00" bypassProxyOnLocal="false" transactionFlow="false" hostNameComparisonMode="StrongWildcard" maxBufferPoolSize="524288" maxReceivedMessageSize="131072" messageEncoding="Text" textEncoding="utf-8" useDefaultWebProxy="true" allowCookies="false"> <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="16384" maxBytesPerRead="4096" maxNameTableCharCount="16384" /> <reliableSession ordered="true" inactivityTimeout="00:10:00" enabled="false" /> <security mode="Message"> <transport clientCredentialType="Windows" proxyCredentialType="None" realm="" /> <message clientCredentialType="Windows" negotiateServiceCredential="true" algorithmSuite="Default" establishSecurityContext="true" /> </security> </binding> </wsHttpBinding> </bindings> <client> <endpoint address="some address" binding="wsHttpBinding" bindingConfiguration="WSHttpBinding_IService" contract="some contact" name="WSHttpBinding_IService" /> </client> Pertinant Exception Section: Exception information: Exception type: TypeLoadException Exception message: Could not load type 'System.Web.UI.ScriptReferenceBase' from assembly 'System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.

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asp.net C# Webcam api error

- by Eyla

Greeting, I'm tring to use webcam api with asp.net and C#. I included all the library and reverince I needed for that. the original code I'm use was for windows application and I'm trying to convert it to asp.net web application. I have start capturing button when I click it, it should start capturing but it gives me an error. the error at this line: hHwnd = capCreateCaptureWindowA(iDevice.ToString(), (WS_VISIBLE | WS_CHILD), 0, 0, 640, 480, picCapture.Handle.ToInt32(), 0); and the error message is: Error 1 'System.Web.UI.WebControls.Image' does not contain a definition for 'Handle' and no extension method 'Handle' accepting a first argument of type 'System.Web.UI.WebControls.Image' could be found (are you missing a using directive or an assembly reference?) C:\Users\Ali\Documents\Visual Studio 2008\Projects\Conference\Conference\Conference1.aspx.cs 63 117 Conference Please advice!! ................................................ here is the complete code ........................................... using System; using System.Collections; using System.Drawing; using System.ComponentModel; using System.Windows.Forms; using System.Configuration; using System.Data; using System.Linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.HtmlControls; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Xml.Linq; using System.Runtime.InteropServices; using System.Drawing.Imaging; using System.Net; using System.Net.Sockets; using System.Threading; using System.IO; namespace Conference { public partial class Conference1 : System.Web.UI.Page { #region WebCam API const short WM_CAP = 1024; const int WM_CAP_DRIVER_CONNECT = WM_CAP + 10; const int WM_CAP_DRIVER_DISCONNECT = WM_CAP + 11; const int WM_CAP_EDIT_COPY = WM_CAP + 30; const int WM_CAP_SET_PREVIEW = WM_CAP + 50; const int WM_CAP_SET_PREVIEWRATE = WM_CAP + 52; const int WM_CAP_SET_SCALE = WM_CAP + 53; const int WS_CHILD = 1073741824; const int WS_VISIBLE = 268435456; const short SWP_NOMOVE = 2; const short SWP_NOSIZE = 1; const short SWP_NOZORDER = 4; const short HWND_BOTTOM = 1; int iDevice = 0; int hHwnd; [System.Runtime.InteropServices.DllImport("user32", EntryPoint = "SendMessageA")] static extern int SendMessage(int hwnd, int wMsg, int wParam, [MarshalAs(UnmanagedType.AsAny)] object lParam); [System.Runtime.InteropServices.DllImport("user32", EntryPoint = "SetWindowPos")] static extern int SetWindowPos(int hwnd, int hWndInsertAfter, int x, int y, int cx, int cy, int wFlags); [System.Runtime.InteropServices.DllImport("user32")] static extern bool DestroyWindow(int hndw); [System.Runtime.InteropServices.DllImport("avicap32.dll")] static extern int capCreateCaptureWindowA(string lpszWindowName, int dwStyle, int x, int y, int nWidth, short nHeight, int hWndParent, int nID); [System.Runtime.InteropServices.DllImport("avicap32.dll")] static extern bool capGetDriverDescriptionA(short wDriver, string lpszName, int cbName, string lpszVer, int cbVer); private void OpenPreviewWindow() { int iHeight = 320; int iWidth = 200; // // Open Preview window in picturebox // hHwnd = capCreateCaptureWindowA(iDevice.ToString(), (WS_VISIBLE | WS_CHILD), 0, 0, 640, 480, picCapture.Handle.ToInt32(), 0); // // Connect to device // if (SendMessage(hHwnd, WM_CAP_DRIVER_CONNECT, iDevice, 0) == 1) { // // Set the preview scale // SendMessage(hHwnd, WM_CAP_SET_SCALE, 1, 0); // // Set the preview rate in milliseconds // SendMessage(hHwnd, WM_CAP_SET_PREVIEWRATE, 66, 0); // // Start previewing the image from the camera // SendMessage(hHwnd, WM_CAP_SET_PREVIEW, 1, 0); // // Resize window to fit in picturebox // SetWindowPos(hHwnd, HWND_BOTTOM, 0, 0, iWidth, iHeight, (SWP_NOMOVE | SWP_NOZORDER)); } else { // // Error connecting to device close window // DestroyWindow(hHwnd); } } private void ClosePreviewWindow() { // // Disconnect from device // SendMessage(hHwnd, WM_CAP_DRIVER_DISCONNECT, iDevice, 0); // // close window // DestroyWindow(hHwnd); } #endregion protected void Page_Load(object sender, EventArgs e) { } protected void btnStart_Click(object sender, EventArgs e) { int iDevice = int.Parse(device_number_textBox.Text); OpenPreviewWindow(); } } }

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java.lang.IllegalStateException: Parent was not null, but this component not related

- by Muneeswaran Balasubramanian

Hi to all, I have the following exception at the time of running jsf program. org.apache.jasper.JasperException: An exception occurred processing JSP page /pages/general/internalServerErrorPage.jsp at line 44 41: <link rel="shortcut icon" href="<%=request.getContextPath()%>/resources/images/infomindzicon.ico" type="image/x-icon" /> 42: </head> 43: <body id="sscmsMainBody"> 44: <h:form id="internalServerErrorPageForm" binding="#{ServerErrorBean.initForm}"> 45: <rich:page id="richPage" theme="#{LayoutSkinBean.layoutTheme}" 46: width="#{LayoutSkinBean.layoutScreenWidth}" 47: sidebarWidth="0"> Caused by: javax.servlet.ServletException: javax.servlet.jsp.JspException: java.lang.IllegalStateException: Parent was not null, but this component not related at org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:858) at org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:791) at org.apache.jsp.pages.general.internalServerErrorPage_jsp._jspService(internalServerErrorPage_jsp.java:207) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:377) What is the meaning of this exception and how can i resolve this?Please help me.Thanks in advance.

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Webcam api error when accessed from ASP.NET Server-side code

- by Eyla

I'm tring to use webcam api with asp.net and C#. I included all the library and references I needed for that. the original code I'm use was for windows application and I'm trying to convert it to asp.net web application. I have start capturing button when I click it, it should start capturing but it gives me an error. the error at this line: hHwnd = capCreateCaptureWindowA(iDevice.ToString(), (WS_VISIBLE | WS_CHILD), 0, 0, 640, 480, picCapture.Handle.ToInt32(), 0); and the error message is: Error 1 'System.Web.UI.WebControls.Image' does not contain a definition for 'Handle' and no extension method 'Handle' accepting a first argument of type 'System.Web.UI.WebControls.Image' could be found (are you missing a using directive or an assembly reference?) C:\Users\Ali\Documents\Visual Studio 2008\Projects\Conference\Conference\Conference1.aspx.cs 63 117 Conference Please advice!! ................................................ here is the complete code ........................................... using System; using System.Collections; using System.Drawing; using System.ComponentModel; using System.Windows.Forms; using System.Configuration; using System.Data; using System.Linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.HtmlControls; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Xml.Linq; using System.Runtime.InteropServices; using System.Drawing.Imaging; using System.Net; using System.Net.Sockets; using System.Threading; using System.IO; namespace Conference { public partial class Conference1 : System.Web.UI.Page { #region WebCam API const short WM_CAP = 1024; const int WM_CAP_DRIVER_CONNECT = WM_CAP + 10; const int WM_CAP_DRIVER_DISCONNECT = WM_CAP + 11; const int WM_CAP_EDIT_COPY = WM_CAP + 30; const int WM_CAP_SET_PREVIEW = WM_CAP + 50; const int WM_CAP_SET_PREVIEWRATE = WM_CAP + 52; const int WM_CAP_SET_SCALE = WM_CAP + 53; const int WS_CHILD = 1073741824; const int WS_VISIBLE = 268435456; const short SWP_NOMOVE = 2; const short SWP_NOSIZE = 1; const short SWP_NOZORDER = 4; const short HWND_BOTTOM = 1; int iDevice = 0; int hHwnd; [System.Runtime.InteropServices.DllImport("user32", EntryPoint = "SendMessageA")] static extern int SendMessage(int hwnd, int wMsg, int wParam, [MarshalAs(UnmanagedType.AsAny)] object lParam); [System.Runtime.InteropServices.DllImport("user32", EntryPoint = "SetWindowPos")] static extern int SetWindowPos(int hwnd, int hWndInsertAfter, int x, int y, int cx, int cy, int wFlags); [System.Runtime.InteropServices.DllImport("user32")] static extern bool DestroyWindow(int hndw); [System.Runtime.InteropServices.DllImport("avicap32.dll")] static extern int capCreateCaptureWindowA(string lpszWindowName, int dwStyle, int x, int y, int nWidth, short nHeight, int hWndParent, int nID); [System.Runtime.InteropServices.DllImport("avicap32.dll")] static extern bool capGetDriverDescriptionA(short wDriver, string lpszName, int cbName, string lpszVer, int cbVer); private void OpenPreviewWindow() { int iHeight = 320; int iWidth = 200; // // Open Preview window in picturebox // hHwnd = capCreateCaptureWindowA(iDevice.ToString(), (WS_VISIBLE | WS_CHILD), 0, 0, 640, 480, picCapture.Handle.ToInt32(), 0); // // Connect to device // if (SendMessage(hHwnd, WM_CAP_DRIVER_CONNECT, iDevice, 0) == 1) { // // Set the preview scale // SendMessage(hHwnd, WM_CAP_SET_SCALE, 1, 0); // // Set the preview rate in milliseconds // SendMessage(hHwnd, WM_CAP_SET_PREVIEWRATE, 66, 0); // // Start previewing the image from the camera // SendMessage(hHwnd, WM_CAP_SET_PREVIEW, 1, 0); // // Resize window to fit in picturebox // SetWindowPos(hHwnd, HWND_BOTTOM, 0, 0, iWidth, iHeight, (SWP_NOMOVE | SWP_NOZORDER)); } else { // // Error connecting to device close window // DestroyWindow(hHwnd); } } private void ClosePreviewWindow() { // // Disconnect from device // SendMessage(hHwnd, WM_CAP_DRIVER_DISCONNECT, iDevice, 0); // // close window // DestroyWindow(hHwnd); } #endregion protected void Page_Load(object sender, EventArgs e) { } protected void btnStart_Click(object sender, EventArgs e) { int iDevice = int.Parse(device_number_textBox.Text); OpenPreviewWindow(); } } }

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Speed improvements for Perl's chameneos-redux script in the Computer Language Benchmarks Game

- by Robert P

Ever looked at the Computer Language Benchmarks Game, (formerly known as the Great Language Shootout)? Perl has some pretty healthy competition there at the moment. It also occurs to me that there's probably some places that Perl's scores could be improved. The biggest one is in the chameneos-redux script right now - the Perl version runs the worst out of any language : 1,626 times slower than the C baseline solution! There are some restrictions on how the programs can be made and optimized, and there is Perl's interpreted runtime penalty, but 1,626 times? There's got to be something that can get the runtime of this program way down. Taking a look at the source code and the challenge, what do you think could be done to reduce this runtime speed?

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.NET remoting manual configuration

- by Quandary

Question: In .NET remoting, I configure the client like this from a config file RemotingConfiguration.Configure("AsyncRemoteAPIclient.exe.config", False) Dim obj As New RemoteAPI.ServiceClass() (with this AsyncRemoteAPIclient.exe.config) <system.runtime.remoting> <application> <client> <wellknown type="RemoteAPI.ServiceClass, ServiceClass" url="http://localhost:8080/ServiceClass.rem" /> </client> <channels> <channel ref="http" port="0" /> </channels> </application> But when I replace the config file with manual configuration with the below code, it stops working, and starts complaining "ServiceClass or dependency not found". Dim chan As New System.Runtime.Remoting.Channels.Http.HttpChannel(0) System.Runtime.Remoting.Channels.ChannelServices.RegisterChannel(chan, False) ' Create an instance of the remote object Dim obj As RemoteAPI.ServiceClass obj = CType(Activator.GetObject(GetType(RemoteAPI.ServiceClass), "http://localhost:8080/ServiceClass.rem"), RemoteAPI.ServiceClass) What's wrong ?

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How many layers are between my program and the hardware?

- by sub

I somehow have the feeling that modern systems, including runtime libraries, this exception handler and that built-in debugger build up more and more layers between my (C++) programs and the CPU/rest of the hardware. I'm thinking of something like this: 1 + 2 OS top layer Runtime library/helper/error handler a hell lot of DLL modules OS kernel layer Do you really want to run 1 + 2?-Windows popup (don't take this serious) OS kernel layer Hardware abstraction Hardware Go through at least 100 miles of circuits Eventually arrive at the CPU ADD 1, 2 Go all the way back to my program Nearly all technical things are simply wrong and in some random order, but you get my point right? How much longer/shorter is this chain when I run a C++ program that calculates 1 + 2 at runtime on Windows? How about when I do this in an interpreter? (Python|Ruby|PHP) Is this chain really as dramatic in reality? Does Windows really try "not to stand in the way"? e.g.: Direct connection my binary < hardware?

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Dynamic data validation in ASP.NET MVC

- by user252160

I've recently read about the model validation capabilities of ASP.NET MVC which are all very cool until a certain point. What happens if the application doesn't know the data that it works with because it is all stored in DB and built together at runtime. Just like in Drupal, I'd like to be able to define custom types at runtime, and assign runtime validation rules as well. Obviously, the idea of assigning attributes to well established models is now gone. What else could be done ? I am thinking in terms of rules being stored as JSON objects in the DB fields or something like that.

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XML serialization and MS/Mono portability

- by Luca

I'm trying to have classes serialized using MS runtime and Mono runtime. While using MS runtime everything goes fine, but using Mono I give me some exception and program startup. The following exception are thrown: There was an error reflecting a type: System.TypeInitializationException (a class) There was an error reflecting a type: System.InvalidOperationException (a class) There was an error reflecting a field: System.ArgumentOutOfRangeException < 0 (an array of classes) The binary was compiled using MS SDK, but I don't think this is the problem. What's going on? .NET shouln't be portable? How to solve these exceptions?

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running Echo from Java

- by ripper234

I'm trying out the Runtime.exec() method to run a command line process. I wrote this sample code, which runs without problems but doesn't produce a file at c:\tmp.txt. String cmdLine = "echo foo > c:\\tmp.txt"; Runtime rt = Runtime.getRuntime(); Process pr = rt.exec(cmdLine); BufferedReader input = new BufferedReader( new InputStreamReader(pr.getInputStream())); String line; StringBuilder output = new StringBuilder(); while ((line = input.readLine()) != null) { output.append(line); } int exitVal = pr.waitFor(); logger.info(String.format("Ran command '%s', got exit code %d, output:\n%s", cmdLine, exitVal, output)); The output is INFO 21-04 20:02:03,024 - Ran command 'echo foo c:\tmp.txt', got exit code 0, output: foo c:\tmp.txt

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Using XCode and instruments to improve iPhone app performance

- by MrDatabase

I've been experimenting with Instruments off and on for a while and and I still can't do the following (with any sensible results): determine or estimate the average runtime of a function that's called many times. For example if I'm driving my gameLoop at 60 Hz with a CADisplayLink I'd like to see how long the loop takes to run on average... 10 ms? 30 ms etc. I've come close with the "CPU activity" instrument but the results are inconsistent or don't make sense. The time profiler seems promising but all I can get is "% of runtime"... and I'd like an actual runtime.

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Java URL("file://") doesn't work on Windows XP

- by Soumya Simanta

For some reason the following code doesn't work on Windows XP. new URL("file://" + tempfile.getAbsolutePath()); I'm using Java 1.6. Java(TM) SE Runtime Environment (build 1.6.0_31-b05) Java HotSpot(TM) Client VM (build 20.6-b01, mixed mode, sharing) However, the same code just works fine in OS X (Lion) and Java 1.6 java version "1.6.0_29" Java(TM) SE Runtime Environment (build 1.6.0_29-b11-402-11M3527) Java HotSpot(TM) 64-Bit Server VM (build 20.4-b02-402, mixed mode) Linux (Linux 2.6.32-38-generic #83-Ubuntu x86_64 GNU/Linux) with Java 1.6 java version "1.6.0_26" Java(TM) SE Runtime Environment (build 1.6.0_26-b03) Java HotSpot(TM) 64-Bit Server VM (build 20.1-b02, mixed mode) Based on this the above code should work.

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Primary reasons why programming language runtimes use stacks?

- by manuel aldana

Many programming language runtime environments use stacks as their primary storage structure (e.g. see JVM bytecode to runtime example). Quickly recalling I see following advantages: Simple structure (pop/push), trivial to implement Most processors are anyway optimized for stack operations, so it is very fast Less problems with memory fragmentation, it is always about moving memory-pointer up and down for allocation and freeing complete blocks of memory by resetting the pointer to the last entry offset. Is the list complete or did I miss something? Are there programming language runtime environments which are not using stacks for storage at all?

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