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  • Why is Python so slow?

    - by Riemannliness
    Why is Python such a slow language, on average, compared to C/C++? I learned Python as my first programming language, but I've only just started with C and already I can feel and see the difference.

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  • Would Python make a good substitute for the Windows command-line/batch scripts?

    - by Lawrence Johnston
    I've got some experience with Bash, which I don't mind, but now that I'm doing a lot of Windows development I'm needing to do basic stuff/write basic scripts using the Windows command-line language. For some reason said language really irritates me, so I was considering learning Python and using that instead. Is Python suitable for such things? Moving files around, creating scripts to do things like unzipping a backup and restoring a SQL database, etc.

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  • How to save the values of one model in another?

    - by ragupathi
    I have user model and Language model where the language model contains different languages and i want the user to select the languages from that model and it should be stored for the corresponding user. Consider there are five languages A, B, C, D, E then the user has to select from the languages. Suppose user 1 selects A and C whereas user 2 selects B and D then the languages has to be stored for that user. How can i do this? please help me.

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  • Java or C for image processing

    - by its-me
    I am looking in to learning a programming language (take a course) for image analysis and processing. Possibly Bioinformatics too. Which language should I go for? C or Java? Other languages are not an option for me. Also please explain why either of the languages is a better option for my application.

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  • Setting up an independent delegate?

    - by fuzzygoat
    Its common for the dataSource and delegate to be the same object, its also common for this object to be the viewController. In all the info/tutorials that I have seen online delegates are always setup as above. If I wanted to create my own class instead can anyone give me any pointers as to how I might do that. Where does that object get instantiated, how do you connect the dataSource and delegate items etc. I am using UITableView to test this.

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  • WebCenter Spaces 11g - UI Customization

    - by john.brunswick
    When developing on top of a portal platform to support an intranet or extranet, a portion of the development time is spent adjusting the out-of-box user templates to adjust the look and feel of the platform for your organization. Generally your deployment will not need to look like anything like the sites posted on http://cssremix.com/ or http://www.webcreme.com/, but will meet business needs by adjusting basic elements like navigation, color palate and logo placement. After spending some time doing custom UI development with WebCenter Spaces 11G I have gathered a few tips that I hope can help to speed anyone's efforts to quickly "skin" a WebCenter Spaces deployment. A detailed white paper was released that outlines a technique to quickly update the UI during runtime - http://www.oracle.com/technology/products/webcenter/pdf/owcs_r11120_cust_skins_runtime_wp.pdf. Customizing at "runtime" means using CSS and images to adjust the page layout and feel, which when creatively done can change the pages drastically. WebCenter also allows for detailed templates to manage the placement of major page elements like menus, sidebar, etc, but by adjusting only images and CSS we can end up with something like the custom solution shown below. view large image Let's dive right in and take a look at some tools to make our efforts more efficient.

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  • .NET Weak Event Handlers – Part II

    - by João Angelo
    On the first part of this article I showed two possible ways to create weak event handlers. One using reflection and the other using a delegate. For this performance analysis we will further differentiate between creating a delegate by providing the type of the listener at compile time (Explicit Delegate) vs creating the delegate with the type of the listener being only obtained at runtime (Implicit Delegate). As expected, the performance between reflection/delegate differ significantly. With the reflection based approach, creating a weak event handler is just storing a MethodInfo reference while with the delegate based approach there is the need to create the delegate which will be invoked later. So, at creating the weak event handler reflection clearly wins, but what about when the handler is invoked. No surprises there, performing a call through reflection every time a handler is invoked is costly. In conclusion, if you want good performance when creating handlers that only sporadically get triggered use reflection, otherwise use the delegate based approach. The explicit delegate approach always wins against the implicit delegate, but I find the syntax for the latter much more intuitive. // Implicit delegate - The listener type is inferred at runtime from the handler parameter public static EventHandler WrapInDelegateCall(EventHandler handler); public static EventHandler<TArgs> WrapInDelegateCall<TArgs>(EventHandler<TArgs> handler) where TArgs : EventArgs; // Explicite delegate - TListener is the type that defines the handler public static EventHandler WrapInDelegateCall<TListener>(EventHandler handler); public static EventHandler<TArgs> WrapInDelegateCall<TArgs, TListener>(EventHandler<TArgs> handler) where TArgs : EventArgs;

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  • In 'apt-cache depends' output, what is the meaning of Suggests, Recommends, |, <>?

    - by fred.bear
    I've checked the man/info page, but there is no reference to some aspects of the output fomat of apt-cache depends The man/info page tried to be helpful (in an obtuse manner); quote: "For the specific meaning of the remainder of the output it is best to consult the apt source code" Now in fairness to the info page, that quote was in regards to the 'showpkg' option which it had reasonably explained, but my option had no such explanation... I understand that Linux info comes from many sources (not just man/info pages), and I don't particularly want to rummage through the source (altough somtimes I do), so here is an example of what I'd like to know the meaning of. # I can assume what these mean, but... # What does | mean? (probably means 'or'???) # What does <pkg> and the following indentations mean? # At the end, the interaction(?) of Suggest and Recommends puzzles me. $ apt-cache depends solr-common solr-common Depends: debconf |Depends: openjdk-6-jre-headless |Depends: <java5-runtime-headless> default-jre-headless gcj-4.4-jre-headless gcj-jre-headless gij-4.3 openjdk-6-jre-headless Depends: <java6-runtime-headless> default-jre-headless openjdk-6-jre-headless Depends: libcommons-codec-java Depends: libcommons-csv-java Depends: libcommons-fileupload-java Depends: libcommons-httpclient-java Depends: libcommons-io-java Depends: libjaxp1.3-java Depends: libjetty-java Depends: liblucene2-java Depends: libservlet2.5-java Depends: libslf4j-java Depends: libxml-commons-external-java Suggests: libmysql-java |Recommends: solr-tomcat Recommends: solr-jetty

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  • DDD Melbourne -lessons leant

    - by Michael Freidgeim
    I've attended DDD Melbourne and want to list the interesting points, that I've leant and want to follow. To read more: * Moles-Mocking Isolation framework for .NET. Documentation is here.   (See also Mocking frameworks comparison created October 4, 2009 ) * WebFormsMVP * PluralSight   http://www.pluralsight-training.net/offers/default.aspx?cc=trial   * ELMAH: Error Logging Modules and Handlers *Rhino.Mocks   * VS UI Test Recorder -see posts Visual Studio 2010 Coded UI Test User Guide. Note that Microsoft Test Manager (MTM) toolis a separate application, that can be started from Program files/VS 2010 menu.It is not a menu inside Visual Studio.   * CodeContract- seems great in Debug. Will be good if in production  will be possible runtime configuration, ability to log instead of throw exception. Current recommendation to customize Debug.Assert is not trivial The programmer is free to use the customization provided by Debug.Assert using assert listeners to obtain whatever runtime behavior they desire (e.g., ignoring the error, logging it, or throwing an exception).   // Clears the existing list of assert listener (the default pop-up box) System.Diagnostics.Debug.Listeners.Clear(); // Install your own listener System.Diagnostics.Debug.Listeners.Add(MyTraceListener); Note that you can't catch specific ContractException, but can catch generic Exception(see How come you cannot catch Code Contract exceptions?)   Books recommended "Working effectively with legacy code" by Michael Feathers (corresponding article)   Fowler, Martin Refactoring: Improving the Design of Existing Code, slides http://jaoo.dk/jaoo1999/schedule/MartinFowlerRefractoring.pdf

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  • value types in the vm

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

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  • Oracle Enterprise Pack for Eclipse (OEPE) 11.1.1.7 adds Oracle ADF Tooling Support

    - by greg.stachnick
    Oracle Enterprise Pack for Eclipse (OEPE) 11.1.1.7 is now available and includes first-time support for Oracle ADF development in Eclipse. Installers for OEPE 11.1.1.7 as well as Eclipse Update instructions can be found on the OEPE downloads page. Here is an overview of the new features of OEPE 11.1.1.7: Support for Oracle ADF Faces Oracle Enterprise Pack for Eclipse (OEPE) 11.1.1.7 now provides support for development with Oracle ADF 11.1.1.4. These features focus on enablement and configuration of the ADF Runtime with Eclipse and WebLogic Server 10.3.4 as well as design time tools for ADF Faces. A new OEPE 11.1.1.7 installer bundles WebLogic Server 10.3.4, Coherence 3.6, and Oracle ADF 11.1.1.4. New Server Extensions allow you to download and install the ADF Runtime libraries into an existing WebLogic Server from within Eclipse. New Project Templates and Facets are available for ADF Faces development (ADF Web). New ADF validators with QuickFix options will check common descriptors for the appropriate ADF configurations. ADF-enabled JSP templates supporting multiple layouts are available under the New menu. New Remote and Local run/deploy support for ADF applications to WebLogic Server 10.3.4 The Palette now supports drag and drop of ADF Faces and Data Visualization Tools (DVT) tags and includes editors for eash tag configuration. The Eclipse Property Sheet has been enhanced to provide advanced ADF tag configuration. AppXRay dependency engine provides improved validation, code completion, and hyperlink navigation for ADF Faces and DVT Tags The Eclipse Web Page Editor enables a more productive source editing experience for ADF Faces. UI Consolidation for WebLogic Server Tools Oracle Enterprise Pack for Eclipse 11.1.1.7 includes a more streamlined UI for WebLogic Server development. You can now view deployments within the Servers view to understand which modules have been deployed to the domain. The MBean Browser View has been merged with the Servers view enabling easier access to MBean values while still allowing Drag and Drop to WLST scripts. WebLogic Server configuration options have been moved to the Properties window, right-click a server configuration and select Properties.

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  • Pivotal Announces JSR-352 Compliance for Spring Batch

    - by reza_rahman
    Pivotal, the company currently funding development of the popular Spring Framework, recently announced JSR 352 (aka Batch Applications for the Java Platform) compliance for the Spring Batch project. More specifically, Spring Batch targets JSR-352 Java SE runtime compatibility rather than Java EE runtime compatibility. If you are surprised that APIs included in Java EE can pass TCKs targeted for Java SE, you should not be. Many other Java EE APIs target compatibility in Java SE environments such as JMS and JPA. You can read about Spring Batch's support for JSR-352 here as well as the Spring configuration to get JSR-352 working in Spring (typically a very low level implementation concern intended to be completely transparent to most JSR-352 users). JSR 352 is one of the few very encouraging cases of major active contribution to the Java EE standard from the Spring development team (the other major effort being Rod Johnson's co-leadership of JSR 330 along with Bob Lee). While IBM's Christopher Vignola led the spec and contributed IBM's years of highly mission critical batch processing experience from products like WebSphere Compute Grid and z/OS batch, the Spring team provided major influences to the API in particular for the chunk processing, listeners, splits and operational interfaces. The GlassFish team's own Mahesh Kannan also contributed, in particular by implementing much of the Java EE integration work for the reference implementation. This was an excellent example of multilateral engineering collaboration through the standards process. For many complex reasons it is not too hard to find evidence of less than amicable interaction between the Spring ecosystem and the Java EE standard over the years if one cares to dig deep enough. In reality most developers see Spring and Java EE as two sides of the same server-side Java coin. At the core Spring and Java EE ecosystems have always shared deep undercurrents of common user bases, bi-directional flows of ideas and perhaps genuine if not begrudging mutual respect. We can all hope for continued strength for both ecosystems and graceful high notes of collaboration via efforts like JSR 352.

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  • An Overview of Batch Processing in Java EE 7

    - by Janice J. Heiss
    Up on otn/java is a new article by Oracle senior software engineer Mahesh Kannan, titled “An Overview of Batch Processing in Java EE 7.0,” which explains the new batch processing capabilities provided by JSR 352 in Java EE 7. Kannan explains that “Batch processing is used in many industries for tasks ranging from payroll processing; statement generation; end-of-day jobs such as interest calculation and ETL (extract, load, and transform) in a data warehouse; and many more. Typically, batch processing is bulk-oriented, non-interactive, and long running—and might be data- or computation-intensive. Batch jobs can be run on schedule or initiated on demand. Also, since batch jobs are typically long-running jobs, check-pointing and restarting are common features found in batch jobs.” JSR 352 defines the programming model for batch applications plus a runtime to run and manage batch jobs. The article covers feature highlights, selected APIs, the structure of Job Scheduling Language, and explains some of the key functions of JSR 352 using a simple payroll processing application. The article also describes how developers can run batch applications using GlassFish Server Open Source Edition 4.0. Kannan summarizes the article as follows: “In this article, we saw how to write, package, and run simple batch applications that use chunk-style steps. We also saw how the checkpoint feature of the batch runtime allows for the easy restart of failed batch jobs. Yet, we have barely scratched the surface of JSR 352. With the full set of Java EE components and features at your disposal, including servlets, EJB beans, CDI beans, EJB automatic timers, and so on, feature-rich batch applications can be written fairly easily.” Check out the article here.

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  • How to use T4 templates in WP7, Silverlight, Desktop or even MonoDroid apps

    - by Daniel Cazzulino
    In other words, how to use T4 templates without ANY runtime dependencies? Yes, it is possible, and quite simple and elegant actually. In a desktop project, just open the Add New Item dialog, and search for "text template": From the two available templates, the one that gives you a zero-dependency runtime-usable template is the first one: Preprocessed Text Template. Once unfolded, you get the .tt file, but also a dependent .cs file automatically generated. Note the Custom Tool associated with the file: If you open up the .cs file, you will see that it doesn't contain the rendered "Hello World!!!" I added in the .tt, but rather a full class named after the template file itself: namespace ConsoleApplication1 { using System; #line 1 "C:\Temp\ConsoleApplication1\ConsoleApplication1\PreTextTemplate1.tt" [System.CodeDom.Compiler.GeneratedCodeAttribute("Microsoft.VisualStudio.TextTemplating", "10.0.0.0")] public partial class PreTextTemplate1 : PreTextTemplate1Base { public virtual string TransformText() { this.GenerationEnvironment = null; this.Write("Hello World!!!"); return this.GenerationEnvironment.ToString(); } } #region Base class ... #endregion } ... Read full article

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  • MMO Data Persistence Question

    - by JasonG
    I wanted to ask a question regarding data persistence strategies for an MMO. I have some experience in the games industry with social synchronous games. At Zynga, we stored static proto data in XML on both the client and the server and stored instance/runtime data in membase. For clarity sake, proto data for a Potion would be PotionName or MaxCharges, while runtime/instance data would be something like ChargesRemaining. So basically, if a player picks up a potion the instance is (via prediction) created from XML data on the client, the request gets sent to the server where the instance is created from XML and then added to membase. Is the same strategy that would be used for soemthing like an MMO? Would it be feasible to have static proto data in some kind of in-memory no-sql database on both client and server with instance data being stored on the server in a more enterprise level database? Or should all data (proto/instance) be stored on the server and the client gets everything from server? I know a lot of this might on certain game requirements, however, i'm basically looking for some general opinion/best practices here if there are any.

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  • Java issues on OpenVZ Ubuntu 11.04 (.jar/.sh files)

    - by IWillNotChange
    I've had a whole line of messes with java and .jar files. I've tried both OpenJDK (from software installer) and about three repositories for Sun. /Desktop# java -jar -Xmx1024m ss.jar Exception in thread "main" java.awt.HeadlessException at java.awt.GraphicsEnvironment.checkHeadless(GraphicsEnvironment.java:173) at java.awt.Window.<init>(Window.java:476) at java.awt.Frame.<init>(Frame.java:419) at java.awt.Frame.<init>(Frame.java:384) at javax.swing.JFrame.<init>(JFrame.java:174) at org.powerbot.bd.<init>(Unknown Source) at org.powerbot.Boot.main(Unknown Source) Two separate errors: ~/Desktop# ./ss.sh [SEVERE] org.server.Boot: Default heap size of 490m too small, restarting with 768m and about 30 different crashes were it just "aborts" with a huge file dump. Each time I've tried something a little different, whether it be updating Java or just changing -Xmx1024 to -Xmx1024m to get rid of the heap. Personally I think it has something to do with OpenVZ, but Google hasn't saved me this time, I need someone who can get to the bottom of my problem. java -version 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) is my current install. Running ss.sh gives me: (I'd post the entire log but its long) # # A fatal error has been detected by the Java Runtime Environment: # # SIGILL (0x4) at pc=0x00002b14278e6fa0, pid=9301, tid=47365590714112 # # JRE version: 6.0_26-b03 # Java VM: Java HotSpot(TM) 64-Bit Server VM (20.1-b02 mixed mode linux-amd64 compressed oops) # Problematic frame: # C [ld-linux-x86-64.so.2+0x14fa0] _dl_make_stack_executable+0x2b50 # # If you would like to submit a bug report, please visit: # http://java.sun.com/webapps/bugreport/crash.jsp # The crash happened outside the Java Virtual Machine in native code. # See problematic frame for where to report the bug. # I'm willing to let someone who knows what they are talking about view it and try and sort this out. Any help would be appreciated, I've about pulled all my hair Googling to no avail.

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  • Solution for installing the ADF 11.1.1.6.0 Runtimes onto a standalone WLS 10.3.6

    - by Chris Muir
    A few customers are hitting the following problem with regards to JDeveloper 11.1.1.6.0 so it's worth documenting a solution. As noted in my previous post the ADF Runtimes for JDeveloper 11.1.1.6.0 will work against a 10.3.5 and 10.3.6 WLS server.  In terms of the JDeveloper 11.1.1.6.0 download Oracle has coupled the 10.3.5 server with that release, not a 10.3.6 server. This has caught some customers out as they are attempting to use the JDeveloper installer to load the 11.1.1.6.0 ADF Runtimes into the middleware home of a standalone 10.3.6 WLS server.  When doing so the installer complains as follows: "The product maintenance level of the current server (WebLogic Server: 10.3.5.0) is not compatible with the maintenance level of the product installed on your system (WebLogic Server: 10.3.6.0).  Please obtain a compatible installer or perform maintenance or your current system to achieve the desired level." The solution is to install the runtimes using the standalone 11.1.1.6.0 ADF Runtime Libraries installer available from OTN (see the options under "Application Development Runtime").

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  • Minecraft in jdk 1.7.0_u2 x64

    - by Nela Drobná
    I have Ubuntu 11.10 64-bit and I installed JDK 1.7.0 update 2 x64 via webupd8 page. But currently I have problem with minecraft game. After downloading launcher from Minecraft.net and lauch the game by java -jar /home/zrebec/Downloads/minecraft.jar launcehr is launched normaly, after login the game download the updates but then I got just the black screen with this in terminal: Setting user: zrebec, -356009615199623309 Exception in thread "Minecraft main thread" java.lang.UnsatisfiedLinkError: /home/zrebec/.minecraft/bin/natives/liblwjgl.so: /home/zrebec/.minecraft/bin/natives/liblwjgl.so: wrong ELF class: ELFCLASS32 (Possible cause: architecture word width mismatch) at java.lang.ClassLoader$NativeLibrary.load(Native Method) at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1928) at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1825) at java.lang.Runtime.load0(Runtime.java:792) at java.lang.System.load(System.java:1059) at org.lwjgl.Sys$1.run(Sys.java:69) at java.security.AccessController.doPrivileged(Native Method) at org.lwjgl.Sys.doLoadLibrary(Sys.java:65) at org.lwjgl.Sys.loadLibrary(Sys.java:81) at org.lwjgl.Sys.<clinit>(Sys.java:98) at org.lwjgl.opengl.Display.<clinit>(Display.java:132) at net.minecraft.client.Minecraft.a(SourceFile:180) at net.minecraft.client.Minecraft.run(SourceFile:648) at java.lang.Thread.run(Thread.java:722) Please anyone can help me with this? I think that problem will be in architecture becase: liblwjgl.so: /home/zrebec/.minecraft/bin/natives/liblwjgl.so: wrong ELF class: ELFCLASS32 (Possible cause: architecture word width mismatch) Any idea please? I know, maybe this one is off topic because maybe its not Ubuntu problem maybe but in 64-bit works all perfectly and I think that accepted answer can help to many users and can make better playing games under linux. Really. Thank you very much for any idea.

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  • Cannot install openjdk on Hardy Heron

    - by infaustus
    I know that Hardy Heron is very old but don't ask why Hardy... I've tried root@vz10931:/etc/apt# apt-get install openjdk-6-jre Reading package lists... Done Building dependency tree Reading state information... Done You might want to run `apt-get -f install' to correct these: The following packages have unmet dependencies: openjdk-6-jre: Depends: libasound2 (> 1.0.14) but it is not going to be installed Depends: libgif4 (>= 4.1.6) but it is not going to be installed Depends: libxtst6 but it is not going to be installed Depends: openjdk-6-jre-headless (>= 6b18-1.8.3-0ubuntu1~8.04.2) but it is not going to be installed vim: Depends: vim-common (= 1:7.1-138+1ubuntu3.1) but 2:7.3.154+hg~74503f6ee649-2ubuntu3 is to be installed E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution). My sources.list deb http://pl.archive.ubuntu.com/ubuntu/ hardy main restricted universe multiverse deb-src http://pl.archive.ubuntu.com/ubuntu/ hardy main restricted universe multiverse deb http://pl.archive.ubuntu.com/ubuntu/ hardy-updates main restricted universe multiverse deb-src http://pl.archive.ubuntu.com/ubuntu/ hardy-updates main restricted universe multiverse deb http://security.ubuntu.com/ubuntu hardy-security main restricted universe multiverse deb-src http://security.ubuntu.com/ubuntu hardy-security main restricted universe multiverse And root@vz10931:/etc/apt# ls -l sources.list.d/ total 0 Please help. When I've tried apt-get install -f I had install new system because everything crashed. Edit: I checked that i have openjdk installed root@vz10931:/var/www/mailer# dpkg --list | grep java iU sun-java6-bin 6.24-1build0.8.04.1 Sun Java(TM) Runtime Environment (JRE) 6 (ar iU sun-java6-jdk 6.24-1build0.8.04.1 Sun Java(TM) Development Kit (JDK) 6 iU sun-java6-jre 6.24-1build0.8.04.1 Sun Java(TM) Runtime Environment (JRE) 6 (ar but when i am trying to start java file: java -jar program.jar error appear -bash: java: command not found

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  • Little mysterious RowMatch

    - by kishore.kondepudi(at)oracle.com
    Incidentally this was the first piece of code i ever wrote in ADF.The requirement was we have tax rates which are read from a table.And there can be different type of tax rates called certificates or exceptions based on the rate_type column in the tax rates table.The simplest design i chose was to create an EO on the tax rates table and create two VO's called CertificateVO and ExceptionVO based on the same EO.So far so good.I wrote all the business logic in the EO and completed the model project.The CertificateVO has the query as select * from tax_rates TaxRateEO where rate_type='CERTIFICATE' and similary the ExceptionVO is also built.The UI is pretty simple and it has two tabs called Certificates and Exceptions and each table has a button to create a tax rate.The certificate tab is driven by CertificateVO and exception tab is driven by ExceptionVO.The CertificateVO has default value of rate_type set to 'CERTIFICATE' and ExceptionVO has default value of rate_type to 'EXCEPTION' to default values for new records.So far so good.But on running the UI i noticed a strange thing,When i create a new row in Certificate i see the same row in Exception too and vice-versa.i.e; what ever row i create in one VO it also appears in the second one although it shouldn't be.I couldn't understand the reason for behavior even though an explicit where clause is present.Digging through documentation i found that ADF doesnt apply the where clause to new rows instead it applies something called as RowMatch to them.RowMatch in simple terms is a where condition applied to the VO rows at runtime.Since we had both VO's based on the same EO we have the same entity cache.The filter factor for new rows to be shown in VO at runtime is actually RowMatch than the where clause defined in the VO.The default RowMatch is empty as a result any new row appears in both the VO's since its from same entity cache.The solution to this problem is to use polymorphic view objects which can do the row filter based on configuration or override the getRowMatch() method in the VOImpl and pass the custom where filter instead of default RowMatch.Eg:@Overridepublic RowMatch getRowMatch(){    return new RowMatch("rate_type='CERTIFICATE'");}similarly for ExceptionVO too.With proper RowMatch in place new rows will route themselves to appropriate VO.PS: The behavior(Same row pushed to both VO's from entity cache) is also called as ViewLink Consistency.Try it out!

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  • Marshalling the value of a char* ANSI string DLL API parameter into a C# string

    - by Brian Biales
    For those who do not mix .NET C# code with legacy DLL's that use char* pointers on a regular basis, the process to convert the strings one way or the other is non-obvious. This is not a comprehensive article on the topic at all, but rather an example of something that took me some time to go find, maybe it will save someone else the time. I am utilizing a third party too that uses a call back function to inform my application of its progress.  This callback includes a pointer that under some circumstances is a pointer to an ANSI character string.  I just need to marshal it into a C# string variable.  Seems pretty simple, yes?  Well, it is, (as are most things, once you know how to do them). The parameter of my callback function is of type IntPtr, which implies it is an integer representation of a pointer.  If I know the pointer is pointing to a simple ANSI string, here is a simple static method to copy it to a C# string: private static string GetStringFromCharStar(IntPtr ptr) {     return System.Runtime.InteropServices.Marshal.PtrToStringAnsi(ptr); } The System.Runtime.InteropServices is where to look any time you are mixing legacy unmanaged code with your .NET application.

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  • Leveraging .Net 4.0 Framework Tools For Encrypting Web Configuration Sections

    - by Sam Abraham
    I would like to share a few points with regards to encrypting web configuration sections in .Net 4.0. This information is also applicable to .Net 3.5 and 2.0. Two methods can work perfectly for encrypting connection strings in a Web project configuration file:   1-Do It All Yourself! In this approach, helper functions for encrypting/decrypting configuration file content are implemented. Program would explicitly retrieve appropriate content from configuration file then decrypt it appropriately.  Disadvantages of this implementation would be the added overhead for maintaining the encryption/decryption code as well the burden of always ensuring sections are appropriately decrypted before use and encrypted appropriately whenever edited.   2- Leverage the .Net 4.0 Framework (The Way to go!) Fortunately, all needed tools for protecting configuration files are built-in to the .Net 2.0/3.5/4.0 versions with very little setup needed. To encrypt connection strings, one can use the ASP.Net IIS Registration Tool (Aspnet_regiis.exe). Note that a 64-bit version of the tool also exists under the Framework64 folder for 64-bit systems. The command we need to encrypt our web.config file connection strings is simply the following:   Aspnet_regiis –pe “connectionstrings” –app “/sampleApplication” –prov “RsaProtectedConfigurationProvider”   To later decrypt this configuration section:   Aspnet_regiis –pd “connectionstrings” –app “/SampleApplication”   The following is a brief description of the command line options used in the example above. Aspnet_regiis supports many more options which you can read about in the links provided for reference below.   Option Description -pe  Section name to encrypt -pd  Section name to decrypt -app  Web application name -prov  Encryption/Decryption provider   ASP.Net automatically decrypts the content of the Web.Config file at runtime so no programming changes are needed.   Another tool, aspnet_setreg.exe is to be used if certain configuration file sections pertinent to the .Net runtime are to be encrypted. For more information on when and how to use aspnet_setreg, please refer to the references below.   Hope this helps!   Some great references concerning the topic:   http://msdn.microsoft.com/en-us/library/ff650037.aspx http://msdn.microsoft.com/en-us/library/zhhddkxy.aspx http://msdn.microsoft.com/en-us/library/dtkwfdky.aspx http://msdn.microsoft.com/en-us/library/68ze1hb2.aspx

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