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• How To Configure Remote Desktop To Hyper-V Guest Virtual Machines

  - by Brian Jackett

  Configuring Remote Desktop (RDP) from a host Hyper-V machine to a guest virtual machine can be tricky, so this post is dedicated to the issues and resolution steps I went through to allow RDP.  Cutting to the point, below are the things to look for followed by some explanation about my scenario if you care to read.  This is not an exhaustive list of what is required, just the items that were causing problems for my particular scenario. Requirements Allow Remote Desktop Connections in guest OS. The network adapter type must allow communication with host machine (e.g. use an “Internal” virtual adapter.) If running Server 2008 R2 on guest, network discovery mode must be turned on. If running Server 2008 R2 on guest, the services supporting network discovery mode must be running: - DNS Client - Function Discovery Resource Publication - SSDP Discovery - UPnP Device Host My Environment     A quick word about my environment.  I am running Windows Server 2008 R2 with Hyper V on my laptop and numerous guest VMs running Windows Server 2003 R2 or Windows Server 2008 R2.  I run a domain controller VM and then 1 or 2 SharePoint servers depending on my work needs.  I’ve found this setup to work well except when it comes to the display window for my VMs. The Issue     Ever since I began running Hyper-V I haven’t been able to RDP to my guest VMs which means the resolution for my connection windows ha been limited to what the native Hyper-V connections allow.  During personal use I can put the resolution up to 1152 x 864, but during presentations I am usually limited to a measly 800 x 600.  That is until today when I decided to fully investigate why I couldn’t connect via RDP.     First a thank you to John Ross (@johnrossjr), Christina Wheeler (@cwheeler76) and Clayton Cobb (@warrtalon) for various suggestions while I was researching tonight.  As it turns out I had not 1, not 2, but 3 items preventing me from using RDP.  Let’s dig into the requirements above. Allow RDP Connection     This item I had previously taken care of, but it bears repeating because by default Windows Server 2008 R2 does not allow RDP connections.  Change the setting from “Don’t allow…” to whichever “Allow connections…” setting suits your needs.  I chose the less secure option as this is just my dev laptop. Network Adapter Type     When I originally configured my VMs I configured each to use 2 network adapters: one using the physical ethernet adapter for internet use and a virtual private adapter for communication between the VMs.  The connection for the ethernet adapter is an "”External” adapter and thus doesn’t connect between the host and guest.  The virtual private adapter allowed communication ONLY between the VMs and not to my host.  There is a third option “Internal” which allows communication between VMs as well as to the host.  After finding out this distinction I promptly created an Internal network adapter and assigned that to my VMs. Turn On Network Discovery     Seems like a pretty common sense thing, but in order to allow remote desktop connections the target computer must able to be found by the source computer (explained here.)  One of the settings that controls if a computer can be found on the network is aptly named Network Discovery.  By default Windows Server 2008 R2 turns Network Discovery off for security purposes.  To enable it open up the Network and Sharing Center.  Click “Change Advanced Sharing Settings” on the left.  On the following screen select “Turn on network discovery” for the currently used profile and click Save Settings.  You may notice though that your selection to turn on network discovery doesn’t save.  If this is the case then you most likely don’t have the supporting services running (as was my case.) Network Discovery Supporting Services     There are a total of 4 services (listed again below) that need to be running before you can turn on network discovery (explained here.)  The below images highlight these services.  In my guest VM I found that I had DNS Client already running while the other 3 were disabled.  I set them all to enabled and started the ones that were stopped.  After this change I returned to the Sharing settings screen and found that Network Discovery was turned on.  I’m not sure whether this was picking up my attempt to turn it on previously or if starting those services turned it on.  Either way the end result was a success. - DNS Client - Function Discovery Resource Publication - SSDP Discovery - UPnP Device Host Before and After Results     The first image is the smaller square shaped viewing window used by the Hyper-V native connection.  The second is the full-screen RDP connection in all its widescreen glory. Conclusion     Over the past few months I’ve found Hyper-V to be very useful for virtualizing my development environments, but I’ve also had a steep learning curve to get various items configured just right.  Allowing RDP connections to guest VMs was one area that I hadn’t been able to get right for the longest time.  Now that I resolved these issues I hope that others can avoid the pitfalls that I ran into.  If you know of any other items I left off feel free to let me know.        -Frog Out   Links Turning on Network Discovery http://sqlblog.com/blogs/john_paul_cook/archive/2009/08/15/remote-desktop-connection-on-windows-server-2008-r2.aspx Services required for Network Discovery http://social.technet.microsoft.com/Forums/en-US/winservergen/thread/2e1fea01-3f2b-4c46-a631-a8db34ed4f84

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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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• Do You Develop Your PL/SQL Directly in the Database?

  - by thatjeffsmith

  I know this sounds like a REALLY weird question for many of you. Let me make one thing clear right away though, I am NOT talking about creating and replacing PLSQL objects directly into a production environment. Do we really need to talk about developers in production again? No, what I am talking about is a developer doing their work from start to finish in a development database. These are generally available to a development team for building the next and greatest version of your databases and database applications. And of course you are using a third party source control system, right? Last week I was in Tampa, FL presenting at the monthly Suncoast Oracle User’s Group meeting. Had a wonderful time, great questions and back-and-forth. My favorite heckler was there, @oraclenered, AKA Chet Justice.  I was in the middle of talking about how it’s better to do your PLSQL work in the Procedure Editor when Chet pipes up - Don’t do it that way, that’s wrong Just press play to edit the PLSQL directly in the database Or something along those lines. I didn’t get what the heck he was talking about. I had been showing how the Procedure Editor gives you much better feedback and support when working with PLSQL. After a few back-and-forths I got to what Chet’s main objection was, and again I’m going to paraphrase: You should develop offline in your SQL worksheet. Don’t do anything in the database until it’s done. I didn’t understand. Were developers expected to be able to internalize and mentally model the PL/SQL engine, see where their errors were, etc in these offline scripts? No, please give Chet more credit than that. What is the ideal Oracle Development Environment? If I were back in the ‘real world’ of database development, I would do all of my development outside of the ‘dev’ instance. My development process looks a little something like this: Do I have a program that already does something like this – copy and paste Has some smart person already written something like this – copy and paste Start typing in the white-screen-of-panic and bungle along until I get something that half-works Tweek, debug, test until I have fooled my subconscious into thinking that it’s ‘good’ As you might understand, I don’t want my co-workers to see the evolution of my code. It would seriously freak them out and I probably wouldn’t have a job anymore (don’t remind me that I already worked myself out of development.) So here’s what I like to do: Run a Local Instance of Oracle on my Machine and Develop My Code Privately I take a copy of development – that’s what source control is for afterall – and run it where no one else can see it. I now get to be my own DBA. If I need a trace – no problem. If I want to run an ASH report, no worries. If I need to create a directory or run some DataPump jobs, that’s all on me. Now when I get my code ‘up to snuff,’ then I will check it into source control and compile it into the official development instance. So my teammates suddenly go from seeing no program, to a mostly complete program. Is this right? If not, it doesn’t seem wrong to me. And after talking to Chet in the car on the way to the local cigar bar, it seems that he’s of the same opinion. So what’s so wrong with coding directly into a development instance? I think ‘wrong’ is a bit strong here. But there are a few pitfalls that you might want to look out for. A few come to mind – and I’m sure Chet could add many more as my memory fails me at the moment. But here goes: Development instance isn’t properly backed up – would hate to lose that work Development is wiped once a week and copied over from Prod – don’t laugh Someone clobbers your code You accidentally on purpose clobber someone else’s code The more developers you have in a single fish pond, the greater chance something ‘bad’ will happen This Isn’t One of Those Posts Where I Tell You What You Should Be Doing I realize many shops won’t be open to allowing developers to stage their own local copies of Oracle. But I would at least be aware that many of your developers are probably doing this anyway – with or without your tacit approval. SQL Developer can do local file tracking, but you should be using Source Control too! I will say that I think it’s imperative that you control your source code outside the database, even if your development team is comprised of a single developer. Store your source code in a file, and control that file in something like Subversion. You would be shocked at the number of teams that do not use a source control system. I know I continue to be shocked no matter how many times I meet another team running by the seat-of-their-pants. I’d love to hear how your development process works. And of course I want to know how SQL Developer and the rest of our tools can better support your processes. And one last thing, if you want a fun and interactive presentation experience, be sure to have Chet in the room

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• .NET Security Part 2

  - by Simon Cooper

  So, how do you create partial-trust appdomains? Where do you come across them? There are two main situations in which your assembly runs as partially-trusted using the Microsoft .NET stack: Creating a CLR assembly in SQL Server with anything other than the UNSAFE permission set. The permissions available in each permission set are given here. Loading an assembly in ASP.NET in any trust level other than Full. Information on ASP.NET trust levels can be found here. You can configure the specific permissions available to assemblies using ASP.NET policy files. Alternatively, you can create your own partially-trusted appdomain in code and directly control the permissions and the full-trust API available to the assemblies you load into the appdomain. This is the scenario I’ll be concentrating on in this post. Creating a partially-trusted appdomain There is a single overload of AppDomain.CreateDomain that allows you to specify the permissions granted to assemblies in that appdomain – this one. This is the only call that allows you to specify a PermissionSet for the domain. All the other calls simply use the permissions of the calling code. If the permissions are restricted, then the resulting appdomain is referred to as a sandboxed domain. There are three things you need to create a sandboxed domain: The specific permissions granted to all assemblies in the domain. The application base (aka working directory) of the domain. The list of assemblies that have full-trust if they are loaded into the sandboxed domain. The third item is what allows us to have a fully-trusted API that is callable by partially-trusted code. I’ll be looking at the details of this in a later post. Granting permissions to the appdomain Firstly, the permissions granted to the appdomain. This is encapsulated in a PermissionSet object, initialized either with no permissions or full-trust permissions. For sandboxed appdomains, the PermissionSet is initialized with no permissions, then you add permissions you want assemblies loaded into that appdomain to have by default: PermissionSet restrictedPerms = new PermissionSet(PermissionState.None); // all assemblies need Execution permission to run at all restrictedPerms.AddPermission( new SecurityPermission(SecurityPermissionFlag.Execution)); // grant general read access to C:\config.xml restrictedPerms.AddPermission( new FileIOPermission(FileIOPermissionAccess.Read, @"C:\config.xml")); // grant permission to perform DNS lookups restrictedPerms.AddPermission( new DnsPermission(PermissionState.Unrestricted)); It’s important to point out that the permissions granted to an appdomain, and so to all assemblies loaded into that appdomain, are usable without needing to go through any SafeCritical code (see my last post if you’re unsure what SafeCritical code is). That is, partially-trusted code loaded into an appdomain with the above permissions (and so running under the Transparent security level) is able to create and manipulate a FileStream object to read from C:\config.xml directly. It is only for operations requiring permissions that are not granted to the appdomain that partially-trusted code is required to call a SafeCritical method that then asserts the missing permissions and performs the operation safely on behalf of the partially-trusted code. The application base of the domain This is simply set as a property on an AppDomainSetup object, and is used as the default directory assemblies are loaded from: AppDomainSetup appDomainSetup = new AppDomainSetup { ApplicationBase = @"C:\temp\sandbox", }; If you’ve read the documentation around sandboxed appdomains, you’ll notice that it mentions a security hole if this parameter is set correctly. I’ll be looking at this, and other pitfalls, that will break the sandbox when using sandboxed appdomains, in a later post. Full-trust assemblies in the appdomain Finally, we need the strong names of the assemblies that, when loaded into the appdomain, will be run as full-trust, irregardless of the permissions specified on the appdomain. These assemblies will contain methods and classes decorated with SafeCritical and Critical attributes. I’ll be covering the details of creating full-trust APIs for partial-trust appdomains in a later post. This is how you get the strongnames of an assembly to be executed as full-trust in the sandbox: // get the Assembly object for the assembly Assembly assemblyWithApi = ... // get the StrongName from the assembly's collection of evidence StrongName apiStrongName = assemblyWithApi.Evidence.GetHostEvidence<StrongName>(); Creating the sandboxed appdomain So, putting these three together, you create the appdomain like so: AppDomain sandbox = AppDomain.CreateDomain( "Sandbox", null, appDomainSetup, restrictedPerms, apiStrongName); You can then load and execute assemblies in this appdomain like any other. For example, to load an assembly into the appdomain and get an instance of the Sandboxed.Entrypoint class, implementing IEntrypoint, you do this: IEntrypoint o = (IEntrypoint)sandbox.CreateInstanceFromAndUnwrap( "C:\temp\sandbox\SandboxedAssembly.dll", "Sandboxed.Entrypoint"); // call method the Execute method on this object within the sandbox o.Execute(); The second parameter to CreateDomain is for security evidence used in the appdomain. This was a feature of the .NET 2 security model, and has been (mostly) obsoleted in the .NET 4 model. Unless the evidence is needed elsewhere (eg. isolated storage), you can pass in null for this parameter. Conclusion That’s the basics of sandboxed appdomains. The most important object is the PermissionSet that defines the permissions available to assemblies running in the appdomain; it is this object that defines the appdomain as full or partial-trust. The appdomain also needs a default directory used for assembly lookups as the ApplicationBase parameter, and you can specify an optional list of the strongnames of assemblies that will be given full-trust permissions if they are loaded into the sandboxed appdomain. Next time, I’ll be looking closer at full-trust assemblies running in a sandboxed appdomain, and what you need to do to make an API available to partial-trust code.

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• SQLAuthority News – Great Time Spent at Great Indian Developers Summit 2014

  - by Pinal Dave

  The Great Indian Developer Conference (GIDS) is one of the most popular annual event held in Bangalore. This year GIDS is scheduled on April 22, 25. I will be presented total four sessions at this event and each session is very different from each other. Here are the details of four of my sessions, which I presented there. Pluralsight Shades This event was a great event and I had fantastic fun presenting a technology over here. I was indeed very excited that along with me, I had many of my friends presenting at the event as well. I want to thank all of you to attend my session and having standing room every single time. I have already sent resources in my newsletter. You can sign up for the newsletter over here. Indexing is an Art I was amazed with the crowd present in the sessions at GIDS. There was a great interest in the subject of SQL Server and Performance Tuning. Audience at GIDS I believe event like such provides a great platform to meet and share knowledge. Pinal at Pluralsight Booth Here are the abstract of the sessions which I had presented. They were recorded so at some point in time they will be available, but if you want the content of all the courses immediately, I suggest you check out my video courses on the same subject on Pluralsight. Indexes, the Unsung Hero Relevant Pluralsight Course Slow Running Queries are the most common problem that developers face while working with SQL Server. While it is easy to blame SQL Server for unsatisfactory performance, the issue often persists with the way queries have been written, and how Indexes has been set up. The session will focus on the ways of identifying problems that slow down SQL Server, and Indexing tricks to fix them. Developers will walk out with scripts and knowledge that can be applied to their servers, immediately post the session. Indexes are the most crucial objects of the database. They are the first stop for any DBA and Developer when it is about performance tuning. There is a good side as well evil side to indexes. To master the art of performance tuning one has to understand the fundamentals of indexes and the best practices associated with the same. We will cover various aspects of Indexing such as Duplicate Index, Redundant Index, Missing Index as well as best practices around Indexes. SQL Server Performance Troubleshooting: Ancient Problems and Modern Solutions Relevant Pluralsight Course Many believe Performance Tuning and Troubleshooting is an art which has been lost in time. However, truth is that art has evolved with time and there are more tools and techniques to overcome ancient troublesome scenarios. There are three major resources that when bottlenecked creates performance problems: CPU, IO, and Memory. In this session we will focus on High CPU scenarios detection and their resolutions. If time permits we will cover other performance related tips and tricks. At the end of this session, attendees will have a clear idea as well as action items regarding what to do when facing any of the above resource intensive scenarios. Developers will walk out with scripts and knowledge that can be applied to their servers, immediately post the session. To master the art of performance tuning one has to understand the fundamentals of performance, tuning and the best practices associated with the same. We will discuss about performance tuning in this session with the help of Demos. Pinal Dave at GIDS MySQL Performance Tuning – Unexplored Territory Relevant Pluralsight Course Performance is one of the most essential aspects of any application. Everyone wants their server to perform optimally and at the best efficiency. However, not many people talk about MySQL and Performance Tuning as it is an extremely unexplored territory. In this session, we will talk about how we can tune MySQL Performance. We will also try and cover other performance related tips and tricks. At the end of this session, attendees will not only have a clear idea, but also carry home action items regarding what to do when facing any of the above resource intensive scenarios. Developers will walk out with scripts and knowledge that can be applied to their servers, immediately post the session. To master the art of performance tuning one has to understand the fundamentals of performance, tuning and the best practices associated with the same. You will also witness some impressive performance tuning demos in this session. Hidden Secrets and Gems of SQL Server We Bet You Never Knew Relevant Pluralsight Course SQL Trio Session! It really amazes us every time when someone says SQL Server is an easy tool to handle and work with. Microsoft has done an amazing work in making working with complex relational database a breeze for developers and administrators alike. Though it looks like child’s play for some, the realities are far away from this notion. The basics and fundamentals though are simple and uniform across databases, the behavior and understanding the nuts and bolts of SQL Server is something we need to master over a period of time. With a collective experience of more than 30+ years amongst the speakers on databases, we will try to take a unique tour of various aspects of SQL Server and bring to you life lessons learnt from working with SQL Server. We will share some of the trade secrets of performance, configuration, new features, tuning, behaviors, T-SQL practices, common pitfalls, productivity tips on tools and more. This is a highly demo filled session for practical use if you are a SQL Server developer or an Administrator. The speakers will be able to stump you and give you answers on almost everything inside the Relational database called SQL Server. I personally attended the session of Vinod Kumar, Balmukund Lakhani, Abhishek Kumar and my favorite Govind Kanshi. Summary If you have missed this event here are two action items 1) Sign up for Resource Newsletter 2) Watch my video courses on Pluralsight Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: MySQL, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, SQLAuthority News, T SQL Tagged: GIDS

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• Session Report - Modern Software Development Anti-Patterns

  - by Janice J. Heiss

  In this standing-room-only session, building upon his 2011 JavaOne Rock Star “Diabolical Developer” session, Martijn Verburg, this time along with Ben Evans, identified and explored common “anti-patterns” – ways of doing things that keep developers from doing their best work. They emphasized the importance of social interaction and team communication, along with identifying certain psychological pitfalls that lead developers astray. Their emphasis was less on technical coding errors and more how to function well and to keep one’s focus on what really matters. They are the authors of the highly regarded The Well-Grounded Java Developer and are both movers and shakers in the London JUG community and on the Java Community Process. The large room was packed as they gave a fast-moving, witty presentation with lots of laughs and personal anecdotes. Below are a few of the anti-patterns they discussed.Anti-Pattern One: Conference-Driven DeliveryThe theme here is the belief that “Real pros hack code and write their slides minutes before their talks.” Their response to this anti-pattern is an expression popular in the military – PPPPPP, which stands for, “Proper preparation prevents piss-poor performance.”“Communication is very important – probably more important than the code you write,” claimed Verburg. “The more you speak in front of large groups of people the easier it gets, but it’s always important to do dry runs, to present to smaller groups. And important to be members of user groups where you can give presentations. It’s a great place to practice speaking skills; to gain new skills; get new contacts, to network.”They encouraged attendees to record themselves and listen to themselves giving a presentation. They advised them to start with a spouse or friends if need be. Learning to communicate to a group, they argued, is essential to being a successful developer. The emphasis here is that software development is a team activity and good, clear, accessible communication is essential to the functioning of software teams. Anti-Pattern Two: Mortgage-Driven Development The main theme here was that, in a period of worldwide recession and economic stagnation, people are concerned about keeping their jobs. So there is a tendency for developers to treat knowledge as power and not share what they know about their systems with their colleagues, so when it comes time to fix a problem in production, they will be the only one who knows how to fix it – and will have made themselves an indispensable cog in a machine so you cannot be fired. So developers avoid documentation at all costs, or if documentation is required, put it on a USB chip and lock it in a lock box. As in the first anti-pattern, the idea here is that communicating well with your colleagues is essential and documentation is a key part of this. Social interactions are essential. Both Verburg and Evans insisted that increasingly, year by year, successful software development is more about communication than the technical aspects of the craft. Developers who understand this are the ones who will have the most success. Anti-Pattern Three: Distracted by Shiny – Always Use the Latest Technology to Stay AheadThe temptation here is to pick out some obscure framework, try a bit of Scala, HTML5, and Clojure, and always use the latest technology and upgrade to the latest point release of everything. Don’t worry if something works poorly because you are ahead of the curve. Verburg and Evans insisted that there need to be sound reasons for everything a developer does. Developers should not bring in something simply because for some reason they just feel like it or because it’s new. They recommended a site run by a developer named Matt Raible with excellent comparison spread sheets regarding Web frameworks and other apps. They praised it as a useful tool to help developers in their decision-making processes. They pointed out that good developers sometimes make bad choices out of boredom, to add shiny things to their CV, out of frustration with existing processes, or just from a lack of understanding. They pointed out that some code may stay in a business system for 15 or 20 years, but not all code is created equal and some may change after 3 or 6 months. Developers need to know where the code they are contributing fits in. What is its likely lifespan? Anti-Pattern Four: Design-Driven Design The anti-pattern: If you want to impress your colleagues and bosses, use design patents left, right, and center – MVC, Session Facades, SOA, etc. Or the UML modeling suite from IBM, back in the day… Generate super fast code. And the more jargon you can talk when in the vicinity of the manager the better.Verburg shared a true story about a time when he was interviewing a guy for a job and asked him what his previous work was. The interviewee said that he essentially took patterns and uses an approved book of Enterprise Architecture Patterns and applied them. Verburg was dumbstruck that someone could have a job in which they took patterns from a book and applied them. He pointed out that the idea that design is a separate activity is simply wrong. He repeated a saying that he uses, “You should pay your junior developers for the lines of code they write and the things they add; you should pay your senior developers for what they take away.”He explained that by encouraging people to take things away, the code base gets simpler and reflects the actual business use cases developers are trying to solve, as opposed to the framework that is being imposed. He told another true story about a project to decommission a very long system. 98% of the code was decommissioned and people got a nice bonus. But the 2% remained on the mainframe so the 98% reduction in code resulted in zero reduction in costs, because the entire mainframe was needed to run the 2% that was left. There is an incentive to get rid of source code and subsystems when they are no longer needed. The session continued with several more anti-patterns that were equally insightful.

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• Using R to Analyze G1GC Log Files

  - by user12620111

  Using R to Analyze G1GC Log Files body, td { font-family: sans-serif; background-color: white; font-size: 12px; margin: 8px; } tt, code, pre { font-family: 'DejaVu Sans Mono', 'Droid Sans Mono', 'Lucida Console', Consolas, Monaco, monospace; } h1 { font-size:2.2em; } h2 { font-size:1.8em; } h3 { font-size:1.4em; } h4 { font-size:1.0em; } h5 { font-size:0.9em; } h6 { font-size:0.8em; } a:visited { color: rgb(50%, 0%, 50%); } pre { margin-top: 0; max-width: 95%; border: 1px solid #ccc; white-space: pre-wrap; } pre code { display: block; padding: 0.5em; } code.r, code.cpp { background-color: #F8F8F8; } table, td, th { border: none; } blockquote { color:#666666; margin:0; padding-left: 1em; border-left: 0.5em #EEE solid; } hr { height: 0px; border-bottom: none; border-top-width: thin; border-top-style: dotted; border-top-color: #999999; } @media print { * { background: transparent !important; color: black !important; filter:none !important; -ms-filter: none !important; } body { 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  Using R to Analyze G1GC Log Files   Using R to Analyze G1GC Log Files Introduction Working in Oracle Platform Integration gives an engineer opportunities to work on a wide array of technologies. My team’s goal is to make Oracle applications run best on the Solaris/SPARC platform. When looking for bottlenecks in a modern applications, one needs to be aware of not only how the CPUs and operating system are executing, but also network, storage, and in some cases, the Java Virtual Machine. I was recently presented with about 1.5 GB of Java Garbage First Garbage Collector log file data. If you’re not familiar with the subject, you might want to review Garbage First Garbage Collector Tuning by Monica Beckwith. The customer had been running Java HotSpot 1.6.0_31 to host a web application server. I was told that the Solaris/SPARC server was running a Java process launched using a commmand line that included the following flags: -d64 -Xms9g -Xmx9g -XX:+UseG1GC -XX:MaxGCPauseMillis=200 -XX:InitiatingHeapOccupancyPercent=80 -XX:PermSize=256m -XX:MaxPermSize=256m -XX:+PrintGC -XX:+PrintGCTimeStamps -XX:+PrintHeapAtGC -XX:+PrintGCDateStamps -XX:+PrintFlagsFinal -XX:+DisableExplicitGC -XX:+UnlockExperimentalVMOptions -XX:ParallelGCThreads=8 Several sources on the internet indicate that if I were to print out the 1.5 GB of log files, it would require enough paper to fill the bed of a pick up truck. Of course, it would be fruitless to try to scan the log files by hand. Tools will be required to summarize the contents of the log files. Others have encountered large Java garbage collection log files. There are existing tools to analyze the log files: IBM’s GC toolkit The chewiebug GCViewer gchisto HPjmeter Instead of using one of the other tools listed, I decide to parse the log files with standard Unix tools, and analyze the data with R. Data Cleansing The log files arrived in two different formats. I guess that the difference is that one set of log files was generated using a more verbose option, maybe -XX:+PrintHeapAtGC, and the other set of log files was generated without that option. Format 1 In some of the log files, the log files with the less verbose format, a single trace, i.e. the report of a singe garbage collection event, looks like this: {Heap before GC invocations=12280 (full 61): garbage-first heap total 9437184K, used 7499918K [0xfffffffd00000000, 0xffffffff40000000, 0xffffffff40000000) region size 4096K, 1 young (4096K), 0 survivors (0K) compacting perm gen total 262144K, used 144077K [0xffffffff40000000, 0xffffffff50000000, 0xffffffff50000000) the space 262144K, 54% used [0xffffffff40000000, 0xffffffff48cb3758, 0xffffffff48cb3800, 0xffffffff50000000) No shared spaces configured. 2014-05-14T07:24:00.988-0700: 60586.353: [GC pause (young) 7324M->7320M(9216M), 0.1567265 secs] Heap after GC invocations=12281 (full 61): garbage-first heap total 9437184K, used 7496533K [0xfffffffd00000000, 0xffffffff40000000, 0xffffffff40000000) region size 4096K, 0 young (0K), 0 survivors (0K) compacting perm gen total 262144K, used 144077K [0xffffffff40000000, 0xffffffff50000000, 0xffffffff50000000) the space 262144K, 54% used [0xffffffff40000000, 0xffffffff48cb3758, 0xffffffff48cb3800, 0xffffffff50000000) No shared spaces configured. } A simple grep can be used to extract a summary: $ grep "\[ GC pause (young" g1gc.log 2014-05-13T13:24:35.091-0700: 3.109: [GC pause (young) 20M->5029K(9216M), 0.0146328 secs] 2014-05-13T13:24:35.440-0700: 3.459: [GC pause (young) 9125K->6077K(9216M), 0.0086723 secs] 2014-05-13T13:24:37.581-0700: 5.599: [GC pause (young) 25M->8470K(9216M), 0.0203820 secs] 2014-05-13T13:24:42.686-0700: 10.704: [GC pause (young) 44M->15M(9216M), 0.0288848 secs] 2014-05-13T13:24:48.941-0700: 16.958: [GC pause (young) 51M->20M(9216M), 0.0491244 secs] 2014-05-13T13:24:56.049-0700: 24.066: [GC pause (young) 92M->26M(9216M), 0.0525368 secs] 2014-05-13T13:25:34.368-0700: 62.383: [GC pause (young) 602M->68M(9216M), 0.1721173 secs] But that format wasn't easily read into R, so I needed to be a bit more tricky. I used the following Unix command to create a summary file that was easy for R to read. $ echo "SecondsSinceLaunch BeforeSize AfterSize TotalSize RealTime" $ grep "\[GC pause (young" g1gc.log | grep -v mark | sed -e 's/[A-SU-z\(\),]/ /g' -e 's/->/ /' -e 's/: / /g' | more SecondsSinceLaunch BeforeSize AfterSize TotalSize RealTime 2014-05-13T13:24:35.091-0700 3.109 20 5029 9216 0.0146328 2014-05-13T13:24:35.440-0700 3.459 9125 6077 9216 0.0086723 2014-05-13T13:24:37.581-0700 5.599 25 8470 9216 0.0203820 2014-05-13T13:24:42.686-0700 10.704 44 15 9216 0.0288848 2014-05-13T13:24:48.941-0700 16.958 51 20 9216 0.0491244 2014-05-13T13:24:56.049-0700 24.066 92 26 9216 0.0525368 2014-05-13T13:25:34.368-0700 62.383 602 68 9216 0.1721173 Format 2 In some of the log files, the log files with the more verbose format, a single trace, i.e. the report of a singe garbage collection event, was more complicated than Format 1. Here is a text file with an example of a single G1GC trace in the second format. As you can see, it is quite complicated. It is nice that there is so much information available, but the level of detail can be overwhelming. I wrote this awk script (download) to summarize each trace on a single line. #!/usr/bin/env awk -f BEGIN { printf("SecondsSinceLaunch IncrementalCount FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize\n") } ###################### # Save count data from lines that are at the start of each G1GC trace. # Each trace starts out like this: # {Heap before GC invocations=14 (full 0): # garbage-first heap total 9437184K, used 325496K [0xfffffffd00000000, 0xffffffff40000000, 0xffffffff40000000) ###################### /{Heap.*full/{ gsub ( "\\)" , "" ); nf=split($0,a,"="); split(a[2],b," "); getline; if ( match($0, "first") ) { G1GC=1; IncrementalCount=b[1]; FullCount=substr( b[3], 1, length(b[3])-1 ); } else { G1GC=0; } } ###################### # Pull out time stamps that are in lines with this format: # 2014-05-12T14:02:06.025-0700: 94.312: [GC pause (young), 0.08870154 secs] ###################### /GC pause/ { DateTime=$1; SecondsSinceLaunch=substr($2, 1, length($2)-1); } ###################### # Heap sizes are in lines that look like this: # [ 4842M->4838M(9216M)] ###################### /\[ .*]$/ { gsub ( "\\[" , "" ); gsub ( "\ \]" , "" ); gsub ( "->" , " " ); gsub ( "\\( " , " " ); gsub ( "\ \)" , " " ); split($0,a," "); if ( split(a[1],b,"M") > 1 ) {BeforeSize=b[1]*1024;} if ( split(a[1],b,"K") > 1 ) {BeforeSize=b[1];} if ( split(a[2],b,"M") > 1 ) {AfterSize=b[1]*1024;} if ( split(a[2],b,"K") > 1 ) {AfterSize=b[1];} if ( split(a[3],b,"M") > 1 ) {TotalSize=b[1]*1024;} if ( split(a[3],b,"K") > 1 ) {TotalSize=b[1];} } ###################### # Emit an output line when you find input that looks like this: # [Times: user=1.41 sys=0.08, real=0.24 secs] ###################### /\[Times/ { if (G1GC==1) { gsub ( "," , "" ); split($2,a,"="); UserTime=a[2]; split($3,a,"="); SysTime=a[2]; split($4,a,"="); RealTime=a[2]; print DateTime,SecondsSinceLaunch,IncrementalCount,FullCount,UserTime,SysTime,RealTime,BeforeSize,AfterSize,TotalSize; G1GC=0; } } The resulting summary is about 25X smaller that the original file, but still difficult for a human to digest. SecondsSinceLaunch IncrementalCount FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize ... 2014-05-12T18:36:34.669-0700: 3985.744 561 0 0.57 0.06 0.16 1724416 1720320 9437184 2014-05-12T18:36:34.839-0700: 3985.914 562 0 0.51 0.06 0.19 1724416 1720320 9437184 2014-05-12T18:36:35.069-0700: 3986.144 563 0 0.60 0.04 0.27 1724416 1721344 9437184 2014-05-12T18:36:35.354-0700: 3986.429 564 0 0.33 0.04 0.09 1725440 1722368 9437184 2014-05-12T18:36:35.545-0700: 3986.620 565 0 0.58 0.04 0.17 1726464 1722368 9437184 2014-05-12T18:36:35.726-0700: 3986.801 566 0 0.43 0.05 0.12 1726464 1722368 9437184 2014-05-12T18:36:35.856-0700: 3986.930 567 0 0.30 0.04 0.07 1726464 1723392 9437184 2014-05-12T18:36:35.947-0700: 3987.023 568 0 0.61 0.04 0.26 1727488 1723392 9437184 2014-05-12T18:36:36.228-0700: 3987.302 569 0 0.46 0.04 0.16 1731584 1724416 9437184 Reading the Data into R Once the GC log data had been cleansed, either by processing the first format with the shell script, or by processing the second format with the awk script, it was easy to read the data into R. g1gc.df = read.csv("summary.txt", row.names = NULL, stringsAsFactors=FALSE,sep="") str(g1gc.df) ## 'data.frame': 8307 obs. of 10 variables: ## $ row.names : chr "2014-05-12T14:00:32.868-0700:" "2014-05-12T14:00:33.179-0700:" "2014-05-12T14:00:33.677-0700:" "2014-05-12T14:00:35.538-0700:" ... ## $ SecondsSinceLaunch: num 1.16 1.47 1.97 3.83 6.1 ... ## $ IncrementalCount : int 0 1 2 3 4 5 6 7 8 9 ... ## $ FullCount : int 0 0 0 0 0 0 0 0 0 0 ... ## $ UserTime : num 0.11 0.05 0.04 0.21 0.08 0.26 0.31 0.33 0.34 0.56 ... ## $ SysTime : num 0.04 0.01 0.01 0.05 0.01 0.06 0.07 0.06 0.07 0.09 ... ## $ RealTime : num 0.02 0.02 0.01 0.04 0.02 0.04 0.05 0.04 0.04 0.06 ... ## $ BeforeSize : int 8192 5496 5768 22528 24576 43008 34816 53248 55296 93184 ... ## $ AfterSize : int 1400 1672 2557 4907 7072 14336 16384 18432 19456 21504 ... ## $ TotalSize : int 9437184 9437184 9437184 9437184 9437184 9437184 9437184 9437184 9437184 9437184 ... head(g1gc.df) ## row.names SecondsSinceLaunch IncrementalCount ## 1 2014-05-12T14:00:32.868-0700: 1.161 0 ## 2 2014-05-12T14:00:33.179-0700: 1.472 1 ## 3 2014-05-12T14:00:33.677-0700: 1.969 2 ## 4 2014-05-12T14:00:35.538-0700: 3.830 3 ## 5 2014-05-12T14:00:37.811-0700: 6.103 4 ## 6 2014-05-12T14:00:41.428-0700: 9.720 5 ## FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize ## 1 0 0.11 0.04 0.02 8192 1400 9437184 ## 2 0 0.05 0.01 0.02 5496 1672 9437184 ## 3 0 0.04 0.01 0.01 5768 2557 9437184 ## 4 0 0.21 0.05 0.04 22528 4907 9437184 ## 5 0 0.08 0.01 0.02 24576 7072 9437184 ## 6 0 0.26 0.06 0.04 43008 14336 9437184 Basic Statistics Once the data has been read into R, simple statistics are very easy to generate. All of the numbers from high school statistics are available via simple commands. For example, generate a summary of every column: summary(g1gc.df) ## row.names SecondsSinceLaunch IncrementalCount FullCount ## Length:8307 Min. : 1 Min. : 0 Min. : 0.0 ## Class :character 1st Qu.: 9977 1st Qu.:2048 1st Qu.: 0.0 ## Mode :character Median :12855 Median :4136 Median : 12.0 ## Mean :12527 Mean :4156 Mean : 31.6 ## 3rd Qu.:15758 3rd Qu.:6262 3rd Qu.: 61.0 ## Max. :55484 Max. :8391 Max. :113.0 ## UserTime SysTime RealTime BeforeSize ## Min. :0.040 Min. :0.0000 Min. : 0.0 Min. : 5476 ## 1st Qu.:0.470 1st Qu.:0.0300 1st Qu.: 0.1 1st Qu.:5137920 ## Median :0.620 Median :0.0300 Median : 0.1 Median :6574080 ## Mean :0.751 Mean :0.0355 Mean : 0.3 Mean :5841855 ## 3rd Qu.:0.920 3rd Qu.:0.0400 3rd Qu.: 0.2 3rd Qu.:7084032 ## Max. :3.370 Max. :1.5600 Max. :488.1 Max. :8696832 ## AfterSize TotalSize ## Min. : 1380 Min. :9437184 ## 1st Qu.:5002752 1st Qu.:9437184 ## Median :6559744 Median :9437184 ## Mean :5785454 Mean :9437184 ## 3rd Qu.:7054336 3rd Qu.:9437184 ## Max. :8482816 Max. :9437184 Q: What is the total amount of User CPU time spent in garbage collection? sum(g1gc.df$UserTime) ## [1] 6236 As you can see, less than two hours of CPU time was spent in garbage collection. Is that too much? To find the percentage of time spent in garbage collection, divide the number above by total_elapsed_time*CPU_count. In this case, there are a lot of CPU’s and it turns out the the overall amount of CPU time spent in garbage collection isn’t a problem when viewed in isolation. When calculating rates, i.e. events per unit time, you need to ask yourself if the rate is homogenous across the time period in the log file. Does the log file include spikes of high activity that should be separately analyzed? Averaging in data from nights and weekends with data from business hours may alias problems. If you have a reason to suspect that the garbage collection rates include peaks and valleys that need independent analysis, see the “Time Series” section, below. Q: How much garbage is collected on each pass? The amount of heap space that is recovered per GC pass is surprisingly low: At least one collection didn’t recover any data. (“Min.=0”) 25% of the passes recovered 3MB or less. (“1st Qu.=3072”) Half of the GC passes recovered 4MB or less. (“Median=4096”) The average amount recovered was 56MB. (“Mean=56390”) 75% of the passes recovered 36MB or less. (“3rd Qu.=36860”) At least one pass recovered 2GB. (“Max.=2121000”) g1gc.df$Delta = g1gc.df$BeforeSize - g1gc.df$AfterSize summary(g1gc.df$Delta) ## Min. 1st Qu. Median Mean 3rd Qu. Max. ## 0 3070 4100 56400 36900 2120000 Q: What is the maximum User CPU time for a single collection? The worst garbage collection (“Max.”) is many standard deviations away from the mean. The data appears to be right skewed. summary(g1gc.df$UserTime) ## Min. 1st Qu. Median Mean 3rd Qu. Max. ## 0.040 0.470 0.620 0.751 0.920 3.370 sd(g1gc.df$UserTime) ## [1] 0.3966 Basic Graphics Once the data is in R, it is trivial to plot the data with formats including dot plots, line charts, bar charts (simple, stacked, grouped), pie charts, boxplots, scatter plots histograms, and kernel density plots. Histogram of User CPU Time per Collection I don't think that this graph requires any explanation. hist(g1gc.df$UserTime, main="User CPU Time per Collection", xlab="Seconds", ylab="Frequency") Box plot to identify outliers When the initial data is viewed with a box plot, you can see the one crazy outlier in the real time per GC. Save this data point for future analysis and drop the outlier so that it’s not throwing off our statistics. Now the box plot shows many outliers, which will be examined later, using times series analysis. Notice that the scale of the x-axis changes drastically once the crazy outlier is removed. par(mfrow=c(2,1)) boxplot(g1gc.df$UserTime,g1gc.df$SysTime,g1gc.df$RealTime, main="Box Plot of Time per GC\n(dominated by a crazy outlier)", names=c("usr","sys","elapsed"), xlab="Seconds per GC", ylab="Time (Seconds)", horizontal = TRUE, outcol="red") crazy.outlier.df=g1gc.df[g1gc.df$RealTime > 400,] g1gc.df=g1gc.df[g1gc.df$RealTime < 400,] boxplot(g1gc.df$UserTime,g1gc.df$SysTime,g1gc.df$RealTime, main="Box Plot of Time per GC\n(crazy outlier excluded)", names=c("usr","sys","elapsed"), xlab="Seconds per GC", ylab="Time (Seconds)", horizontal = TRUE, outcol="red") box(which = "outer", lty = "solid") Here is the crazy outlier for future analysis: crazy.outlier.df ## row.names SecondsSinceLaunch IncrementalCount ## 8233 2014-05-12T23:15:43.903-0700: 20741 8316 ## FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize ## 8233 112 0.55 0.42 488.1 8381440 8235008 9437184 ## Delta ## 8233 146432 R Time Series Data To analyze the garbage collection as a time series, I’ll use Z’s Ordered Observations (zoo). “zoo is the creator for an S3 class of indexed totally ordered observations which includes irregular time series.” require(zoo) ## Loading required package: zoo ## ## Attaching package: 'zoo' ## ## The following objects are masked from 'package:base': ## ## as.Date, as.Date.numeric head(g1gc.df[,1]) ## [1] "2014-05-12T14:00:32.868-0700:" "2014-05-12T14:00:33.179-0700:" ## [3] "2014-05-12T14:00:33.677-0700:" "2014-05-12T14:00:35.538-0700:" ## [5] "2014-05-12T14:00:37.811-0700:" "2014-05-12T14:00:41.428-0700:" options("digits.secs"=3) times=as.POSIXct( g1gc.df[,1], format="%Y-%m-%dT%H:%M:%OS%z:") g1gc.z = zoo(g1gc.df[,-c(1)], order.by=times) head(g1gc.z) ## SecondsSinceLaunch IncrementalCount FullCount ## 2014-05-12 17:00:32.868 1.161 0 0 ## 2014-05-12 17:00:33.178 1.472 1 0 ## 2014-05-12 17:00:33.677 1.969 2 0 ## 2014-05-12 17:00:35.538 3.830 3 0 ## 2014-05-12 17:00:37.811 6.103 4 0 ## 2014-05-12 17:00:41.427 9.720 5 0 ## UserTime SysTime RealTime BeforeSize AfterSize ## 2014-05-12 17:00:32.868 0.11 0.04 0.02 8192 1400 ## 2014-05-12 17:00:33.178 0.05 0.01 0.02 5496 1672 ## 2014-05-12 17:00:33.677 0.04 0.01 0.01 5768 2557 ## 2014-05-12 17:00:35.538 0.21 0.05 0.04 22528 4907 ## 2014-05-12 17:00:37.811 0.08 0.01 0.02 24576 7072 ## 2014-05-12 17:00:41.427 0.26 0.06 0.04 43008 14336 ## TotalSize Delta ## 2014-05-12 17:00:32.868 9437184 6792 ## 2014-05-12 17:00:33.178 9437184 3824 ## 2014-05-12 17:00:33.677 9437184 3211 ## 2014-05-12 17:00:35.538 9437184 17621 ## 2014-05-12 17:00:37.811 9437184 17504 ## 2014-05-12 17:00:41.427 9437184 28672 Example of Two Benchmark Runs in One Log File The data in the following graph is from a different log file, not the one of primary interest to this article. I’m including this image because it is an example of idle periods followed by busy periods. It would be uninteresting to average the rate of garbage collection over the entire log file period. More interesting would be the rate of garbage collect in the two busy periods. Are they the same or different? Your production data may be similar, for example, bursts when employees return from lunch and idle times on weekend evenings, etc. Once the data is in an R Time Series, you can analyze isolated time windows. Clipping the Time Series data Flashing back to our test case… Viewing the data as a time series is interesting. You can see that the work intensive time period is between 9:00 PM and 3:00 AM. Lets clip the data to the interesting period:     par(mfrow=c(2,1)) plot(g1gc.z$UserTime, type="h", main="User Time per GC\nTime: Complete Log File", xlab="Time of Day", ylab="CPU Seconds per GC", col="#1b9e77") clipped.g1gc.z=window(g1gc.z, start=as.POSIXct("2014-05-12 21:00:00"), end=as.POSIXct("2014-05-13 03:00:00")) plot(clipped.g1gc.z$UserTime, type="h", main="User Time per GC\nTime: Limited to Benchmark Execution", xlab="Time of Day", ylab="CPU Seconds per GC", col="#1b9e77") box(which = "outer", lty = "solid") Cumulative Incremental and Full GC count Here is the cumulative incremental and full GC count. When the line is very steep, it indicates that the GCs are repeating very quickly. Notice that the scale on the Y axis is different for full vs. incremental. plot(clipped.g1gc.z[,c(2:3)], main="Cumulative Incremental and Full GC count", xlab="Time of Day", col="#1b9e77") GC Analysis of Benchmark Execution using Time Series data In the following series of 3 graphs: The “After Size” show the amount of heap space in use after each garbage collection. Many Java objects are still referenced, i.e. alive, during each garbage collection. This may indicate that the application has a memory leak, or may indicate that the application has a very large memory footprint. Typically, an application's memory footprint plateau's in the early stage of execution. One would expect this graph to have a flat top. The steep decline in the heap space may indicate that the application crashed after 2:00. The second graph shows that the outliers in real execution time, discussed above, occur near 2:00. when the Java heap seems to be quite full. The third graph shows that Full GCs are infrequent during the first few hours of execution. The rate of Full GC's, (the slope of the cummulative Full GC line), changes near midnight.   plot(clipped.g1gc.z[,c("AfterSize","RealTime","FullCount")], xlab="Time of Day", col=c("#1b9e77","red","#1b9e77")) GC Analysis of heap recovered Each GC trace includes the amount of heap space in use before and after the individual GC event. During garbage coolection, unreferenced objects are identified, the space holding the unreferenced objects is freed, and thus, the difference in before and after usage indicates how much space has been freed. The following box plot and bar chart both demonstrate the same point - the amount of heap space freed per garbage colloection is surprisingly low. par(mfrow=c(2,1)) boxplot(as.vector(clipped.g1gc.z$Delta), main="Amount of Heap Recovered per GC Pass", xlab="Size in KB", horizontal = TRUE, col="red") hist(as.vector(clipped.g1gc.z$Delta), main="Amount of Heap Recovered per GC Pass", xlab="Size in KB", breaks=100, col="red") box(which = "outer", lty = "solid") This graph is the most interesting. The dark blue area shows how much heap is occupied by referenced Java objects. This represents memory that holds live data. The red fringe at the top shows how much data was recovered after each garbage collection. barplot(clipped.g1gc.z[,c("AfterSize","Delta")], col=c("#7570b3","#e7298a"), xlab="Time of Day", border=NA) legend("topleft", c("Live Objects","Heap Recovered on GC"), fill=c("#7570b3","#e7298a")) box(which = "outer", lty = "solid") When I discuss the data in the log files with the customer, I will ask for an explaination for the large amount of referenced data resident in the Java heap. There are two are posibilities: There is a memory leak and the amount of space required to hold referenced objects will continue to grow, limited only by the maximum heap size. After the maximum heap size is reached, the JVM will throw an “Out of Memory” exception every time that the application tries to allocate a new object. If this is the case, the aplication needs to be debugged to identify why old objects are referenced when they are no longer needed. The application has a legitimate requirement to keep a large amount of data in memory. The customer may want to further increase the maximum heap size. Another possible solution would be to partition the application across multiple cluster nodes, where each node has responsibility for managing a unique subset of the data. Conclusion In conclusion, R is a very powerful tool for the analysis of Java garbage collection log files. The primary difficulty is data cleansing so that information can be read into an R data frame. Once the data has been read into R, a rich set of tools may be used for thorough evaluation.

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• Avoiding coupling

  - by Seralize

  It is also true that a system may become so coupled, where each class is dependent on other classes that depend on other classes, that it is no longer possible to make a change in one place without having a ripple effect and having to make subsequent changes in many places.[1] This is why using an interface or an abstract class can be valuable in any object-oriented software project. Quote from Wikipedia Starting from scratch I'm starting from scratch with a project that I recently finished because I found the code to be too tightly coupled and hard to refactor, even when using MVC. I will be using MVC on my new project aswell but want to try and avoid the pitfalls this time, hopefully with your help. Project summary My issue is that I really wish to keep the Controller as clean as possible, but it seems like I can't do this. The basic idea of the program is that the user picks wordlists which is sent to the game engine. It will pick random words from the lists until there are none left. Problem at hand My main problem is that the game will have 'modes', and need to check the input in different ways through a method called checkWord(), but exactly where to put this and how to abstract it properly is a challenge to me. I'm new to design patterns, so not sure whether there exist any might fit my problem. My own attempt at abstraction Here is what I've gotten so far after hours of 'refactoring' the design plans, and I know it's long, but it's the best I could do to try and give you an overview (Note: As this is the sketch, anything is subject to change, all help and advice is very welcome. Also note the marked coupling points): Wordlist class Wordlist { // Basic CRUD etc. here! // Other sample methods: public function wordlistCount($user_id) {} // Returns count of how many wordlists a user has public function getAll($user_id) {} // Returns all wordlists of a user } Word class Word { // Basic CRUD etc. here! // Other sample methods: public function wordCount($wordlist_id) {} // Returns count of words in a wordlist public function getAll($wordlist_id) {} // Returns all words from a wordlist public function getWordInfo($word_id) {} // Returns information about a word } Wordpicker class Wordpicker { // The class needs to know which words and wordlists to exclude protected $_used_words = array(); protected $_used_wordlists = array(); // Wordlists to pick words from protected $_wordlists = array(); /* Public Methods */ public function setWordlists($wordlists = array()) {} public function setUsedWords($used_words = array()) {} public function setUsedWordlists($used_wordlists = array()) {} public function getRandomWord() {} // COUPLING POINT! Will most likely need to communicate with both the Wordlist and Word classes /* Protected Methods */ protected function _checkAvailableWordlists() {} // COUPLING POINT! Might need to check if wordlists are deleted etc. protected function _checkAvailableWords() {} // COUPLING POINT! Method needs to get all words in a wordlist from the Word class } Game class Game { protected $_session_id; // The ID of a game session which gets stored in the database along with game details protected $_game_info = array(); // Game instantiation public function __construct($user_id) { if (! $this->_session_id = $this->_gameExists($user_id)) { // New game } else { // Resume game } } // This is the method I tried to make flexible by using abstract classes etc. // Does it even belong in this class at all? public function checkWord($answer, $native_word, $translation) {} // This method checks the answer against the native word / translation word, depending on game mode public function getGameInfo() {} // Returns information about a game session, or creates it if it does not exist public function deleteSession($session_id) {} // Deletes a game session from the database // Methods dealing with game session information protected function _gameExists($user_id) {} protected function _getProgress($session_id) {} protected function _updateProgress($game_info = array()) {} } The Game /* CONTROLLER */ /* "Guess the word" page */ // User input $game_type = $_POST['game_type']; // Chosen with radio buttons etc. $wordlists = $_POST['wordlists']; // Chosen with checkboxes etc. // Starts a new game or resumes one from the database $game = new Game($_SESSION['user_id']); $game_info = $game->getGameInfo(); // Instantiates a new Wordpicker $wordpicker = new Wordpicker(); $wordpicker->setWordlists((isset($game_info['wordlists'])) ? $game_info['wordlists'] : $wordlists); $wordpicker->setUsedWordlists((isset($game_info['used_wordlists'])) ? $game_info['used_wordlists'] : NULL); $wordpicker->setUsedWords((isset($game_info['used_words'])) ? $game_info['used_words'] : NULL); // Fetches an available word if (! $word_id = $wordpicker->getRandomWord()) { // No more words left - game over! $game->deleteSession($game_info['id']); redirect(); } else { // Presents word details to the user $word = new Word(); $word_info = $word->getWordInfo($word_id); } The Bit to Finish /* CONTROLLER */ /* "Check the answer" page */ // ?????????????????? ( http://pastebin.com/cc6MtLTR ) Make sure you toggle the 'Layout Width' to the right for a better view. Thanks in advance. Questions To which extent should objects be loosely coupled? If object A needs info from object B, how is it supposed to get this without losing too much cohesion? As suggested in the comments, models should hold all business logic. However, as objects should be independent, where to glue them together? Should the model contain some sort of "index" or "client" area which connects the dots? Edit: So basically what I should do for a start is to make a new model which I can more easily call with oneliners such as $model->doAction(); // Lots of code in here which uses classes! How about the method for checking words? Should it be it's own object? I'm not sure where I should put it as it's pretty much part of the 'game'. But on another hand, I could just leave out the 'abstraction and OOPness' and make it a method of the 'client model' which will be encapsulated from the controller anyway. Very unsure about this.

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• How to understand these lines in apache.log

  - by chefnelone

  I just get 19000 lines like these in the apache.log file for my site example.com. My hosting provider shut down the hosting and notified me that I need to avoid to activate my hosting again. I understand that I got a big amount of visits but I don't know how to avoid this. 88.190.47.233 - - [27/Jun/2013:09:51:34 +0200] "GET / HTTP/1.0" 403 389 "http://example.com/" "Opera/9.80 (Windows NT 6.1; U; ru) Presto/2.10.289 Version/12.02" 417 88.190.47.233 - - [27/Jun/2013:09:51:34 +0200] "GET / HTTP/1.0" 403 389 "http://example.com/" "Opera/9.80 (Windows NT 6.1; U; ru) Presto/2.10.289 Version/12.02" 417 175.44.28.155 - - [27/Jun/2013:09:51:44 +0200] "GET /en/user/register HTTP/1.1" 403 503 "http://example.com/en/" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1;)" 248 175.44.29.140 - - [27/Jun/2013:09:53:19 +0200] "GET /en/node/1557?page=2 HTTP/1.0" 403 517 "http://example.com/en/node/1557?page=2" "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.12 Safari/535.11" 491 These are the lines from apache-error.log. There are more than 35000 lines like this. [Thu Jun 27 09:50:58 2013] [error] [client 5.39.19.183] (13)Permission denied: access to /index.php denied, referer: http://example.com/ [Thu Jun 27 09:51:03 2013] [error] [client 125.112.29.105] (13)Permission denied: access to /index.php denied, referer: http://example.com/en/ [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.php denied, referer: http://example.com/en/node/1557?page=1#comment-701 [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.php denied, referer: http://example.com/en/node/1557?page=1#comment-701 [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.html denied, referer: http://example.com/en/node/1557?page=1#comment-701 [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.htm denied, referer: http://example.com/en/node/1557?page=1#comment-701 [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.php denied, referer: http://example.com/ [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.html denied, referer: http://example.com/ [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.htm denied, referer: http://example.com/ [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.php denied, referer: http://example.com/ [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.html denied, referer: http://example.com/ [Thu Jun 27 09:51:34 2013] [error] [client 88.190.47.233] (13)Permission denied: access to /index.htm denied, referer: http://example.com/ [Thu Jun 27 09:51:44 2013] [error] [client 175.44.28.155] (13)Permission denied: access to /index.php denied, referer: http://example.com/en/ [Thu Jun 27 09:53:19 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.php denied, referer: http://example.com/en/node/1557?page=2 [Thu Jun 27 09:53:20 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.php denied, referer: http://example.com/en/node/1557?page=2 [Thu Jun 27 09:53:20 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.html denied, referer: http://example.com/en/node/1557?page=2 [Thu Jun 27 09:53:20 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.htm denied, referer: http://example.com/en/node/1557?page=2 [Thu Jun 27 09:53:21 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.php denied, referer: http://example.com/ [Thu Jun 27 09:53:21 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.html denied, referer: http://example.com/ [Thu Jun 27 09:53:21 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.htm denied, referer: http://example.com/ [Thu Jun 27 09:53:22 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.php denied, referer: http://example.com/ [Thu Jun 27 09:53:22 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.html denied, referer: http://example.com/ [Thu Jun 27 09:53:22 2013] [error] [client 175.44.29.140] (13)Permission denied: access to /index.htm denied, referer: http://example.com/ [Thu Jun 27 09:56:53 2013] [error] [client 113.246.6.147] (13)Permission denied: access to /index.php denied, referer: http://example.com/en/ [Thu Jun 27 09:58:58 2013] [error] [client 108.62.71.180] (13)Permission denied: access to /index.php denied, referer: http://example.com/

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• How to restore Linode to Vagrant VM?

  - by Iain Elder

  I'm trying to set up a Linux development environment so I can safely make changes to my website without breaking the live site. Linode hosts my live site. A simple solution would be to host my development server on Linode as well, but I want to avoid doubling my hosting costs. The cheapest way I see is to use Vagrant on my Windows workstation to host my development environment. After I attempt to restore the backup to Vagrant and reboot the VM, I can no longer ssh into the Vagrant host. It's probably because by restoring the backup I overwrite some special Vagrant configuration, but I'm not sure how to avoid that. How do I make this approach work? If my approach is fundamentally wrong, can you suggest an alternative? Creating the backup On the Linode I used these commands to create a compressed copy of the entire filesystem, while ignoring things that shouldn't be included in the backup: $ sudo rsync -ahvz --exclude={/dev/*,/proc/*,/sys/*,/tmp/*,/run/*,/mnt/*,/backup/*} /* /backup/2 $ sudo tar -czf /backup/2.gz /backup/2 The backup file is called 2.gz because this is thesecond backup. The first backup is called 1.gz. I use WinSCP to copy the backup file to my Windows workstation. Setting up the Vagrant host I need a Vagrant box that matches my Linode operating system (Ubuntu 12.04.3 LTS, kernel 3.9.3). I selected the closet match from vagrantbox.es: Ubuntu Server Precise 12.04.3 amd64 Kernel is ready for Docker (Docker not included) On my workstation I ran these commands to add the box and initialize and boot an instance: $ vagrant box add ubuntu-precise http://nitron-vagrant.s3-website-us-east-1.amazonaws.com/vagrant_ubuntu_12.04.3_amd64_virtualbox.box $ mkdir linode-test $ cd linode-test $ vagrant init ubuntu-precise $ vagrant up Now Vagrant is running a machine with SSH on port 2222. The operating system version is the same. The kernel version is 3.8.0. Sounds close enough. Restoring the backup With WinSCP I copied the backup file 2.gz to /home/vagrant/2.gz on the Vagrant box. With PuTTY I connected via ssh to my new Vagrant box: On the box move the backup to the filesystem root. $ sudo mv 2.gz / Extract the archive to the filesystem root: $ sudo tar -xvpz -f 2.gz -C / --strip-components=2 (I discovered I need to use strip components because all files in the archive have the prefix backup/2/. I'll fix this for the next backup.) After the tar command completes, I log out of the box. Testing the backup When I try to log in again, it doesn't let me log in as vagrant with a password any more. It does let me log in as iain, my user on the live Linode, with a password. That surprised me because I disabled password authentication on my live Linode. I figured that I have to restart the ssh service for the change to take effect. Instead of restarting just ssh, I chose to restart the whole system. Now I can't even get to the login screen. PuTTY says "connection refused" when I try to connect. What went wrong?

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• File Server - Storage configuration: RAID vs LVM vs ZFS something else... ?

  - by privatehuff

  We are a small company that does video editing, among other things, and need a place to keep backup copies of large media files and make it easy to share them. I've got a box set up with Ubuntu Server and 4 x 500 GB drives. They're currently set up with Samba as four shared folders that Mac/Windows workstations can see fine, but I want a better solution. There are two major reasons for this: 500 GB is not really big enough (some projects are larger) It is cumbersome to manage the current setup, because individual hard drives have different amounts of free space and duplicated data (for backup). It is confusing now and that will only get worse once there are multiple servers. ("the project is on sever2 in share4" etc) So, I need a way to combine hard drives in such a way as to avoid complete data loss with the failure of a single drive, and so users see only a single share on each server. I've done linux software RAID5 and had a bad experience with it, but would try it again. LVM looks ok but it seems like no one uses it. ZFS seems interesting but it is relatively "new". What is the most efficient and least risky way to to combine the hdd's that is convenient for my users? Edit: The Goal here is basically to create servers that contain an arbitrary number of hard drives but limit complexity from an end-user perspective. (i.e. they see one "folder" per server) Backing up data is not an issue here, but how each solution responds to hardware failure is a serious concern. That is why I lump RAID, LVM, ZFS, and who-knows-what together. My prior experience with RAID5 was also on an Ubuntu Server box and there was a tricky and unlikely set of circumstances that led to complete data loss. I could avoid that again but was left with a feeling that I was adding an unnecessary additional point of failure to the system. I haven't used RAID10 but we are on commodity hardware and the most data drives per box is pretty much fixed at 6. We've got a lot of 500 GB drives and 1.5 TB is pretty small. (Still an option for at least one server, however) I have no experience with LVM and have read conflicting reports on how it handles drive failure. If a (non-striped) LVM setup could handle a single drive failing and only loose whichever files had a portion stored on that drive (and stored most files on a single drive only) we could even live with that. But as long as I have to learn something totally new, I may as well go all the way to ZFS. Unlike LVM, though, I would also have to change my operating system (?) so that increases the distance between where I am and where I want to be. I used a version of solaris at uni and wouldn't mind it terribly, though. On the other end on the IT spectrum, I think I may also explore FreeNAS and/or Openfiler, but that doesn't really solve the how-to-combine-drives issue.

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• Ajax Control Toolkit December 2013 Release

  - by Stephen.Walther

  Today, we released a new version of the Ajax Control Toolkit that contains several important bug fixes and new features. The new release contains a new Tabs control that has been entirely rewritten in jQuery. You can download the December 2013 release of the Ajax Control Toolkit at http://Ajax.CodePlex.com. Alternatively, you can install the latest version directly from NuGet: The Ajax Control Toolkit and jQuery The Ajax Control Toolkit now contains two controls written with jQuery: the ToggleButton control and the Tabs control.  The goal is to rewrite the Ajax Control Toolkit to use jQuery instead of the Microsoft Ajax Library gradually over time. The motivation for rewriting the controls in the Ajax Control Toolkit to use jQuery is to modernize the toolkit. We want to continue to accept new controls written for the Ajax Control Toolkit contributed by the community. The community wants to use jQuery. We want to make it easy for the community to submit bug fixes. The community understands jQuery. Using the Ajax Control Toolkit with a Website that Already uses jQuery But what if you are already using jQuery in your website?  Will adding the Ajax Control Toolkit to your website break your existing website?  No, and here is why. The Ajax Control Toolkit uses jQuery.noConflict() to avoid conflicting with an existing version of jQuery in a page.  The version of jQuery that the Ajax Control Toolkit uses is represented by a variable named actJQuery.  You can use actJQuery side-by-side with an existing version of jQuery in a page without conflict.Imagine, for example, that you add jQuery to an ASP.NET page using a <script> tag like this: <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="TestACTDec2013.WebForm1" %> <!DOCTYPE html> <html > <head runat="server"> <title></title> </head> <body> <form id="form1" runat="server"> <div> <script src="Scripts/jquery-2.0.3.min.js"></script> <ajaxToolkit:ToolkitScriptManager runat="server" /> <ajaxToolkit:TabContainer runat="server"> <ajaxToolkit:TabPanel runat="server"> <HeaderTemplate> Tab 1 </HeaderTemplate> <ContentTemplate> <h1>First Tab</h1> </ContentTemplate> </ajaxToolkit:TabPanel> <ajaxToolkit:TabPanel runat="server"> <HeaderTemplate> Tab 2 </HeaderTemplate> <ContentTemplate> <h1>Second Tab</h1> </ContentTemplate> </ajaxToolkit:TabPanel> </ajaxToolkit:TabContainer> </div> </form> </body> </html> The page above uses the Ajax Control Toolkit Tabs control (TabContainer and TabPanel controls).  The Tabs control uses the version of jQuery that is currently bundled with the Ajax Control Toolkit (jQuery version 1.9.1). The page above also includes a <script> tag that references jQuery version 2.0.3.  You might need that particular version of jQuery, for example, to use a particular jQuery plugin. The two versions of jQuery in the page do not create a conflict. This fact can be demonstrated by entering the following two commands in the JavaScript console window: actJQuery.fn.jquery $.fn.jquery Typing actJQuery.fn.jquery will display the version of jQuery used by the Ajax Control Toolkit and typing $.fn.jquery (or jQuery.fn.jquery) will show the version of jQuery used by other jQuery plugins in the page.      Preventing jQuery from Loading Twice So by default, the Ajax Control Toolkit will not conflict with any existing version of jQuery used in your application. However, this does mean that if you are already using jQuery in your application then jQuery will be loaded twice. For performance reasons, you might want to avoid loading the jQuery library twice. By taking advantage of the <remove> element in the AjaxControlToolkit.config file, you can prevent the Ajax Control Toolkit from loading its version of jQuery. <ajaxControlToolkit> <scripts> <remove name="jQuery.jQuery.js" /> </scripts> <controlBundles> <controlBundle> <control name="TabContainer" /> <control name="TabPanel" /> </controlBundle> </controlBundles> </ajaxControlToolkit> Be careful here:  the name of the script being removed – jQuery.jQuery.js – is case-sensitive. If you remove jQuery then it is your responsibility to add the exact same version of jQuery back into your application.  You can add jQuery back using a <script> tag like this: <script src="Scripts/jquery-1.9.1.min.js"></script>     Make sure that you add the <script> tag before the server-side <form> tag or the Ajax Control Toolkit won’t detect the presence of jQuery. Alternatively, you can use the ToolkitScriptManager like this: <ajaxToolkit:ToolkitScriptManager runat="server"> <Scripts> <asp:ScriptReference Name="jQuery.jQuery.js" /> </Scripts> </ajaxToolkit:ToolkitScriptManager> The Ajax Control Toolkit is tested against the particular version of jQuery that is bundled with the Ajax Control Toolkit. Currently, the Ajax Control Toolkit uses jQuery version 1.9.1. If you attempt to use a different version of jQuery with the Ajax Control Toolkit then you will get the exception jQuery 1.9.1 is required in your JavaScript console window: If you need to use a different version of jQuery in the same page as the Ajax Control Toolkit then you should not use the <remove> element. Instead, allow the Ajax Control Toolkit to load its version of jQuery side-by-side with the other version of jQuery. Lots of Bug Fixes As usual, we implemented several important bug fixes with this release. The bug fixes concerned the following three controls: Tabs control – In the course of rewriting the Tabs control to use jQuery, we fixed several bugs related to the Tabs control. AjaxFileUpload control – We resolved an issue concerning the AjaxFileUpload and the TMP directory. HTMLEditor control – We updated the HTMLEditor control to use the new Ajax Control Toolkit bundling and minification framework. Summary I would like to thank the Superexpert team for their hard work on this release. Many long hours of coding and testing went into making this release possible.

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• Ajax Control Toolkit and Superexpert

  - by Stephen Walther

  Microsoft has asked my company, Superexpert Consulting, to take ownership of the development and maintenance of the Ajax Control Toolkit moving forward. In this blog entry, I discuss our strategy for improving the Ajax Control Toolkit. Why the Ajax Control Toolkit? The Ajax Control Toolkit is one of the most popular projects on CodePlex. In fact, some have argued that it is among the most successful open-source projects of all time. It consistently receives over 3,500 downloads a day (not weekends -- workdays). A mind-boggling number of developers use the Ajax Control Toolkit in their ASP.NET Web Forms applications. Why does the Ajax Control Toolkit continue to be such a popular project? The Ajax Control Toolkit fills a strong need in the ASP.NET Web Forms world. The Toolkit enables Web Forms developers to build richly interactive JavaScript applications without writing any JavaScript. For example, by taking advantage of the Ajax Control Toolkit, a Web Forms developer can add modal dialogs, popup calendars, and client tabs to a web application simply by dragging web controls onto a page. The Ajax Control Toolkit is not for everyone. If you are comfortable writing JavaScript then I recommend that you investigate using jQuery plugins instead of the Ajax Control Toolkit. However, if you are a Web Forms developer and you don’t want to get your hands dirty writing JavaScript, then the Ajax Control Toolkit is a great solution. The Ajax Control Toolkit is Vast The Ajax Control Toolkit consists of 40 controls. That’s a lot of controls (For the sake of comparison, jQuery UI consists of only 8 controls – those slackers J). Furthermore, developers expect the Ajax Control Toolkit to work on browsers both old and new. For example, people expect the Ajax Control Toolkit to work with Internet Explorer 6 and Internet Explorer 9 and every version of Internet Explorer in between. People also expect the Ajax Control Toolkit to work on the latest versions of Mozilla Firefox, Apple Safari, and Google Chrome. And, people expect the Ajax Control Toolkit to work with different operating systems. Yikes, that is a lot of combinations. The biggest challenge which my company faces in supporting the Ajax Control Toolkit is ensuring that the Ajax Control Toolkit works across all of these different browsers and operating systems. Testing, Testing, Testing Because we wanted to ensure that we could easily test the Ajax Control Toolkit with different browsers, the very first thing that we did was to set up a dedicated testing server. The dedicated server -- named Schizo -- hosts 4 virtual machines so that we can run Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, and Internet Explorer 9 at the same time (We also use the virtual machines to host the latest versions of Firefox, Chrome, Opera, and Safari). The five developers on our team (plus me) can each publish to a separate FTP website on the testing server. That way, we can quickly test how changes to the Ajax Control Toolkit affect different browsers. QUnit Tests for the Ajax Control Toolkit Introducing regressions – introducing new bugs when trying to fix existing bugs – is the concern which prevents me from sleeping well at night. There are so many people using the Ajax Control Toolkit in so many unique scenarios, that it is difficult to make improvements to the Ajax Control Toolkit without introducing regressions. In order to avoid regressions, we decided early on that it was extremely important to build good test coverage for the 40 controls in the Ajax Control Toolkit. We’ve been focusing a lot of energy on building automated JavaScript unit tests which we can use to help us discover regressions. We decided to write the unit tests with the QUnit test framework. We picked QUnit because it is quickly becoming the standard unit testing framework in the JavaScript world. For example, it is the unit testing framework used by the jQuery team, the jQuery UI team, and many jQuery UI plugin developers. We had to make several enhancements to the QUnit framework in order to test the Ajax Control Toolkit. For example, QUnit does not support tests which include postbacks. We modified the QUnit framework so that it works with IFrames so we could perform postbacks in our automated tests. At this point, we have written hundreds of QUnit tests. For example, we have written 135 QUnit tests for the Accordion control. The QUnit tests are included with the Ajax Control Toolkit source code in a project named AjaxControlToolkit.Tests. You can run all of the QUnit tests contained in the project by opening the Default.aspx page. Automating the QUnit Tests across Multiple Browsers Automated tests are useless if no one ever runs them. In order for the QUnit tests to be useful, we needed an easy way to run the tests automatically against a matrix of browsers. We wanted to run the unit tests against Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, Internet Explorer 9, Firefox, Chrome, and Safari automatically. Expecting a developer to run QUnit tests against every browser after every check-in is just too much to expect. It takes 20 seconds to run the Accordion QUnit tests. We are testing against 8 browsers. That would require the developer to open 8 browsers and wait for the results after each change in code. Too much work. Therefore, we built a JavaScript Test Server. Our JavaScript Test Server project was inspired by John Resig’s TestSwarm project. The JavaScript Test Server runs our QUnit tests in a swarm of browsers (running on different operating systems) automatically. Here’s how the JavaScript Test Server works: 1. We created an ASP.NET page named RunTest.aspx that constantly polls the JavaScript Test Server for a new set of QUnit tests to run. After the RunTest.aspx page runs the QUnit tests, the RunTest.aspx records the test results back to the JavaScript Test Server. 2. We opened the RunTest.aspx page on instances of Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, Internet Explorer 9, FireFox, Chrome, Opera, Google, and Safari. Now that we have the JavaScript Test Server setup, we can run all of our QUnit tests against all of the browsers which we need to support with a single click of a button. A New Release of the Ajax Control Toolkit Each Month The Ajax Control Toolkit Issue Tracker contains over one thousand five hundred open issues and feature requests. So we have plenty of work on our plates J At CodePlex, anyone can vote for an issue to be fixed. Originally, we planned to fix issues in order of their votes. However, we quickly discovered that this approach was inefficient. Constantly switching back and forth between different controls was too time-consuming. It takes time to re-familiarize yourself with a control. Instead, we decided to focus on two or three controls each month and really focus on fixing the issues with those controls. This way, we can fix sets of related issues and avoid the randomization caused by context switching. Our team works in monthly sprints. We plan to do another release of the Ajax Control Toolkit each and every month. So far, we have competed one release of the Ajax Control Toolkit which was released on April 1, 2011. We plan to release a new version in early May. Conclusion Fortunately, I work with a team of smart developers. We currently have 5 developers working on the Ajax Control Toolkit (not full-time, they are also building two very cool ASP.NET MVC applications). All the developers who work on our team are required to have strong JavaScript, jQuery, and ASP.NET MVC skills. In the interest of being as transparent as possible about our work on the Ajax Control Toolkit, I plan to blog frequently about our team’s ongoing work. In my next blog entry, I plan to write about the two Ajax Control Toolkit controls which are the focus of our work for next release.

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• Parallelism in .NET – Part 5, Partitioning of Work

  - by Reed

  When parallelizing any routine, we start by decomposing the problem.  Once the problem is understood, we need to break our work into separate tasks, so each task can be run on a different processing element.  This process is called partitioning. Partitioning our tasks is a challenging feat.  There are opposing forces at work here: too many partitions adds overhead, too few partitions leaves processors idle.  Trying to work the perfect balance between the two extremes is the goal for which we should aim.  Luckily, the Task Parallel Library automatically handles much of this process.  However, there are situations where the default partitioning may not be appropriate, and knowledge of our routines may allow us to guide the framework to making better decisions. First off, I’d like to say that this is a more advanced topic.  It is perfectly acceptable to use the parallel constructs in the framework without considering the partitioning taking place.  The default behavior in the Task Parallel Library is very well-behaved, even for unusual work loads, and should rarely be adjusted.  I have found few situations where the default partitioning behavior in the TPL is not as good or better than my own hand-written partitioning routines, and recommend using the defaults unless there is a strong, measured, and profiled reason to avoid using them.  However, understanding partitioning, and how the TPL partitions your data, helps in understanding the proper usage of the TPL. I indirectly mentioned partitioning while discussing aggregation.  Typically, our systems will have a limited number of Processing Elements (PE), which is the terminology used for hardware capable of processing a stream of instructions.  For example, in a standard Intel i7 system, there are four processor cores, each of which has two potential hardware threads due to Hyperthreading.  This gives us a total of 8 PEs – theoretically, we can have up to eight operations occurring concurrently within our system. In order to fully exploit this power, we need to partition our work into Tasks.  A task is a simple set of instructions that can be run on a PE.  Ideally, we want to have at least one task per PE in the system, since fewer tasks means that some of our processing power will be sitting idle.  A naive implementation would be to just take our data, and partition it with one element in our collection being treated as one task.  When we loop through our collection in parallel, using this approach, we’d just process one item at a time, then reuse that thread to process the next, etc.  There’s a flaw in this approach, however.  It will tend to be slower than necessary, often slower than processing the data serially. The problem is that there is overhead associated with each task.  When we take a simple foreach loop body and implement it using the TPL, we add overhead.  First, we change the body from a simple statement to a delegate, which must be invoked.  In order to invoke the delegate on a separate thread, the delegate gets added to the ThreadPool’s current work queue, and the ThreadPool must pull this off the queue, assign it to a free thread, then execute it.  If our collection had one million elements, the overhead of trying to spawn one million tasks would destroy our performance. The answer, here, is to partition our collection into groups, and have each group of elements treated as a single task.  By adding a partitioning step, we can break our total work into small enough tasks to keep our processors busy, but large enough tasks to avoid overburdening the ThreadPool.  There are two clear, opposing goals here: Always try to keep each processor working, but also try to keep the individual partitions as large as possible. When using Parallel.For, the partitioning is always handled automatically.  At first, partitioning here seems simple.  A naive implementation would merely split the total element count up by the number of PEs in the system, and assign a chunk of data to each processor.  Many hand-written partitioning schemes work in this exactly manner.  This perfectly balanced, static partitioning scheme works very well if the amount of work is constant for each element.  However, this is rarely the case.  Often, the length of time required to process an element grows as we progress through the collection, especially if we’re doing numerical computations.  In this case, the first PEs will finish early, and sit idle waiting on the last chunks to finish.  Sometimes, work can decrease as we progress, since previous computations may be used to speed up later computations.  In this situation, the first chunks will be working far longer than the last chunks.  In order to balance the workload, many implementations create many small chunks, and reuse threads.  This adds overhead, but does provide better load balancing, which in turn improves performance. The Task Parallel Library handles this more elaborately.  Chunks are determined at runtime, and start small.  They grow slowly over time, getting larger and larger.  This tends to lead to a near optimum load balancing, even in odd cases such as increasing or decreasing workloads.  Parallel.ForEach is a bit more complicated, however. When working with a generic IEnumerable<T>, the number of items required for processing is not known in advance, and must be discovered at runtime.  In addition, since we don’t have direct access to each element, the scheduler must enumerate the collection to process it.  Since IEnumerable<T> is not thread safe, it must lock on elements as it enumerates, create temporary collections for each chunk to process, and schedule this out.  By default, it uses a partitioning method similar to the one described above.  We can see this directly by looking at the Visual Partitioning sample shipped by the Task Parallel Library team, and available as part of the Samples for Parallel Programming.  When we run the sample, with four cores and the default, Load Balancing partitioning scheme, we see this: The colored bands represent each processing core.  You can see that, when we started (at the top), we begin with very small bands of color.  As the routine progresses through the Parallel.ForEach, the chunks get larger and larger (seen by larger and larger stripes). Most of the time, this is fantastic behavior, and most likely will out perform any custom written partitioning.  However, if your routine is not scaling well, it may be due to a failure in the default partitioning to handle your specific case.  With prior knowledge about your work, it may be possible to partition data more meaningfully than the default Partitioner. There is the option to use an overload of Parallel.ForEach which takes a Partitioner<T> instance.  The Partitioner<T> class is an abstract class which allows for both static and dynamic partitioning.  By overriding Partitioner<T>.SupportsDynamicPartitions, you can specify whether a dynamic approach is available.  If not, your custom Partitioner<T> subclass would override GetPartitions(int), which returns a list of IEnumerator<T> instances.  These are then used by the Parallel class to split work up amongst processors.  When dynamic partitioning is available, GetDynamicPartitions() is used, which returns an IEnumerable<T> for each partition.  If you do decide to implement your own Partitioner<T>, keep in mind the goals and tradeoffs of different partitioning strategies, and design appropriately. The Samples for Parallel Programming project includes a ChunkPartitioner class in the ParallelExtensionsExtras project.  This provides example code for implementing your own, custom allocation strategies, including a static allocator of a given chunk size.  Although implementing your own Partitioner<T> is possible, as I mentioned above, this is rarely required or useful in practice.  The default behavior of the TPL is very good, often better than any hand written partitioning strategy.

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• DropDownList and SelectListItem Array Item Updates in MVC

  - by Rick Strahl

  So I ran into an interesting behavior today as I deployed my first MVC 4 app tonight. I have a list form that has a filter drop down that allows selection of categories. This list is static and rarely changes so rather than loading these items from the database each time I load the items once and then cache the actual SelectListItem[] array in a static property. However, when we put the site online tonight we immediately noticed that the drop down list was coming up with pre-set values that randomly changed. Didn't take me long to trace this back to the cached list of SelectListItem[]. Clearly the list was getting updated - apparently through the model binding process in the selection postback. To clarify the scenario here's the drop down list definition in the Razor View:@Html.DropDownListFor(mod => mod.QueryParameters.Category, Model.CategoryList, "All Categories") where Model.CategoryList gets set with:[HttpPost] [CompressContent] public ActionResult List(MessageListViewModel model) { InitializeViewModel(model); busEntry entryBus = new busEntry(); var entries = entryBus.GetEntryList(model.QueryParameters); model.Entries = entries; model.DisplayMode = ApplicationDisplayModes.Standard; model.CategoryList = AppUtils.GetCachedCategoryList(); return View(model); } The AppUtils.GetCachedCategoryList() method gets the cached list or loads the list on the first access. The code to load up the list is housed in a Web utility class. The method looks like this:/// <summary> /// Returns a static category list that is cached /// </summary> /// <returns></returns> public static SelectListItem[] GetCachedCategoryList() { if (_CategoryList != null) return _CategoryList; lock (_SyncLock) { if (_CategoryList != null) return _CategoryList; var catBus = new busCategory(); var categories = catBus.GetCategories().ToList(); // Turn list into a SelectItem list var catList= categories .Select(cat => new SelectListItem() { Text = cat.Name, Value = cat.Id.ToString() }) .ToList(); catList.Insert(0, new SelectListItem() { Value = ((int)SpecialCategories.AllCategoriesButRealEstate).ToString(), Text = "All Categories except Real Estate" }); catList.Insert(1, new SelectListItem() { Value = "-1", Text = "--------------------------------" }); _CategoryList = catList.ToArray(); } return _CategoryList; } private static SelectListItem[] _CategoryList ; This seemed normal enough to me - I've been doing stuff like this forever caching smallish lists in memory to avoid an extra trip to the database. This list is used in various places throughout the application - for the list display and also when adding new items and setting up for notifications etc.. Watch that ModelBinder! However, it turns out that this code is clearly causing a problem. It appears that the model binder on the [HttpPost] method is actually updating the list that's bound to and changing the actual entry item in the list and setting its selected value. If you look at the code above I'm not setting the SelectListItem.Selected value anywhere - the only place this value can get set is through ModelBinding. Sure enough when stepping through the code I see that when an item is selected the actual model - model.CategoryList[x].Selected - reflects that. This is bad on several levels: First it's obviously affecting the application behavior - nobody wants to see their drop down list values jump all over the place randomly. But it's also a problem because the array is getting updated by multiple ASP.NET threads which likely would lead to odd crashes from time to time. Not good! In retrospect the modelbinding behavior makes perfect sense. The actual items and the Selected property is the ModelBinder's way of keeping track of one or more selected values. So while I assumed the list to be read-only, the ModelBinder is actually updating it on a post back producing the rather surprising results. Totally missed this during testing and is another one of those little - "Did you know?" moments. So, is there a way around this? Yes but it's maybe not quite obvious. I can't change the behavior of the ModelBinder, but I can certainly change the way that the list is generated. Rather than returning the cached list, I can return a brand new cloned list from the cached items like this:/// <summary> /// Returns a static category list that is cached /// </summary> /// <returns></returns> public static SelectListItem[] GetCachedCategoryList() { if (_CategoryList != null) { // Have to create new instances via projection // to avoid ModelBinding updates to affect this // globally return _CategoryList .Select(cat => new SelectListItem() { Value = cat.Value, Text = cat.Text }) .ToArray(); } …}  The key is that newly created instances of SelectListItems are returned not just filtered instances of the original list. The key here is 'new instances' so that the ModelBinding updates do not update the actual static instance. The code above uses LINQ and a projection into new SelectListItem instances to create this array of fresh instances. And this code works correctly - no more cross-talk between users. Unfortunately this code is also less efficient - it has to reselect the items and uses extra memory for the new array. Knowing what I know now I probably would have not cached the list and just take the hit to read from the database. If there is even a possibility of thread clashes I'm very wary of creating code like this. But since the method already exists and handles this load in one place this fix was easy enough to put in. Live and learn. It's little things like this that can cause some interesting head scratchers sometimes…© Rick Strahl, West Wind Technologies, 2005-2012Posted in MVC  ASP.NET  .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Adaptive ADF/WebCenter template for the iPad

  - by Maiko Rocha

  One of my WebCenter Portal customers was asking about adaptive design with ADF/WebCenter Portal and how they could go about creating an adaptive iPad template for their WebCenter Portal application. They were looking not only for the out-of-the-box support for mobile Safari which is certified against PS5+ (11.1.1.6) for ADF/WebCenter - but also to create a specific template to streamline their workflow on the iPad. Seems like they wanted something in the lines of Yahoo! Mail provides for the iPad - so the example I will use is shamelessly inspired by Y! Mail's iPad UI.  But first, let's quickly understand how can we bake in some adaptive goodness into ADF Faces. First thing we need to understand is, yes, there are a couple of constraints that we will need to work around, namely, the use or layout managers and skins. Please also keep in mind that I'm not and I don't pretend to be a web designer, much less an UX specialist, so feel free to leave your thoughts on the matter in the comments section. Now, back to the limitations. Layout Managers ADF Faces layout managers create an abstraction on top of the generated HTML code for a page so a developer doesn't need to be worried about how to size and dimension the UI layout (eg, af:panelStretchLayout). Although layout managers are very helpful, in this specific situation we will need to know a little bit more of how the final HTML is being rendered so we can apply the CSS class accordingly and create transition containers where the media queries will be applied - now, if you're using 11gR2 (11.1.2.2.3) there's the new component af:panelGridLayout (here and here) that will greatly improve creating responsive templates and pages because it is based on the grid/fluid systems and will generate straight out to DIVs on your final page. For now, I'm limited to PS5 and the af:panelStretchLayout component as a starting point because that's the release my customer is on. Skins You won't be able to use media queries, or use anything with "@" notation on the skin CSS file - the skin pre-processor will remove all extraneous "@" from the CSS file. The solution is to split your CSS in two separate files: a skin CSS file and plain CSS where you will add the media queries. The issue here is that you won't be able to use media queries for any faces components. We can, though, still apply the media queries for the components like af:panelGroupLayout and af:panelBorderLayout through their styleClass property to enable these components to be responsive to to the iPad orientation, by changing its dimensions, font sizes, hide/show areas, etc. Difference between responsive and adaptive design The best definition of adaptive vs responsive web design I could find is this: “Responsive web design,” as coined by Ethan Marcotte, means “fluid grids, fluid images/media & media queries.” “Adaptive web design,” as I use it, is about creating interfaces that adapt to the user’s capabilities (in terms of both form and function). To me, “adaptive web design” is just another term for “progressive enhancement” of which responsive web design can (an often should) be an integral part, but is a more holistic approach to web design in that it also takes into account varying levels of markup, CSS, JavaScript and assistive technology support. Responsive/adapative web design is much more than slapping an HTML template with CSS around your content or application. The content and application themselves are part of your web design - in other words, a responsive template is just an afterthought if it is not originating from a responsive design the involves the whole web application/s. Tips on responsive / adapative design with ADF/WebCenter Some of the tips listed below were already mentioned in multiple blog posts about ADF layout and skinning, but it is still worth remembering: a simple guideline for ADF/WebCenter apps would be to first create a high-level group of devices, for example: smartphones, tablets,  and desktop. For each of these large groups, create the basic structure to provide responsiveness: a page template, a skin, and an external CSS: pagetemplate_smartphone.jspx, smartphone_skin.css, smartphone-responsive.css pagetemplate_tablet.jspx, tablet_skin.css, tablet-responsive.css pagetemplate_desktop.jspx, desktop_skin.css, desktop-responsive.css These three assets can be changed on the fly through an user-agent check on the server side, delivering the right UI to the right device. Within each of the assets, you can make fine adjustments for each subgroup of devices with media queries - for example, smart phones with different screen dimensions and pixel density. Having these three groups and the corresponding assets per group seem to be a good compromise between trying to put everything on a single set of assets - specially considering the constraints above - and going to the other side of the spectrum to create assets per discrete device (iPhone4, iPhone5, Nexus, S3, etc.). Keep in mind that these are my rules and are not in any shape or form a best practice - this is how it fits best for the scenarios I've been working with. If you need to use HTML tags on your page, surround them with af:group to protect the DOM structure For stretchable/fluid layouts: Use non-stretching containers: panelGroupLayout, panelBorderLayout, … panelBorderLayout can be used to approximate HTML table component To avoid multiple scroll bars, do not nest scrolling PanelGroupLayout components. Consider layout="vertical" For stretchable/fluid layouts: Most stretchable ADF components also work in flowing context with dimensionsFrom="auto" To stretch a component horizontally, use styleClass="AFStretchWidth" instead of  "width:100%" Skinning Don't use CSS3 @media, @import, animations, etc. on skin css files. They will be removed. CSS3 properties within a class (box-shadow, transition, etc.) work just fine. Consider resetting some skin classes to better control their rendering: body {color: inherit;font: inherit;} af|document {-tr-inhibit: all;} af|commandLink {-tr-inhibit: all;} af|goLink {-tr-inhibit: all;} af|inputText::content {font: inherit;} Specific meta tags and CSS properties: Use  <meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0"/> to avoid zooming (if you want) Use -webkit-overflow-scrolling: touch to enable native momentum scrolling within overflown areas (here) Use text-rendering: optmizeLegibility to improve readability. (here) User text-overflow: ellipsis to gracefully crop overflown text. (here) The meta-tags are included in each and every page in the metaContainer facet of af:document tag. You can also use a javascript to inject the meta-tags from the template. For the purpose of the example, I wanted to use as few workarounds as possible.   The iPad template and sample application This sample application has been built as a WebCenter Portal application, but you will also be able to reuse the template and techniques on your vanilla ADF application. Keep in mind that I'm neither a designer nor a CSS specialist, so please don't bash me too much on the messy CSS file you'll find on the application.  I've extended the provided PreferencesBean class that comes with WebCenter Portal and added code to dinamically change the template and skin on the fly.   This is the sample application in landscape orientation: This is the sample application in portrait orientation - the left side menu hides automatically based on a CSS media query: Another screenshot with a skinned popup opened: This is a sample application for you to play with - ideally you shouldn't use it as a starting point. On the left side bar you will find links rendered from a WebCenter Portal navigation model - the link triggers a full request through an af:goLink, while the light blue PPR button triggers a PPR navigation. The dark blue toolbar buttons at the top don't have any function,while the Approve and Reject buttons show a skinned popup. The search box of course doesn't have any behavior attahed to it either. There's a known issue right now with some PPR calls that are randomly generating a 403 error redirecting to the login page - I didn't have time to investigate if this is iOS6 specific or not - if you have any insights please let me know your findings. You can download the sample here.

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• New <%: %> Syntax for HTML Encoding Output in ASP.NET 4 (and ASP.NET MVC 2)

  - by ScottGu

  [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] This is the nineteenth in a series of blog posts I’m doing on the upcoming VS 2010 and .NET 4 release. Today’s post covers a small, but very useful, new syntax feature being introduced with ASP.NET 4 – which is the ability to automatically HTML encode output within code nuggets.  This helps protect your applications and sites against cross-site script injection (XSS) and HTML injection attacks, and enables you to do so using a nice concise syntax. HTML Encoding Cross-site script injection (XSS) and HTML encoding attacks are two of the most common security issues that plague web-sites and applications.  They occur when hackers find a way to inject client-side script or HTML markup into web-pages that are then viewed by other visitors to a site.  This can be used to both vandalize a site, as well as enable hackers to run client-script code that steals cookie data and/or exploits a user’s identity on a site to do bad things. One way to help mitigate against cross-site scripting attacks is to make sure that rendered output is HTML encoded within a page.  This helps ensures that any content that might have been input/modified by an end-user cannot be output back onto a page containing tags like <script> or <img> elements.  ASP.NET applications (especially those using ASP.NET MVC) often rely on using <%= %> code-nugget expressions to render output.  Developers today often use the Server.HtmlEncode() or HttpUtility.Encode() helper methods within these expressions to HTML encode the output before it is rendered.  This can be done using code like below: While this works fine, there are two downsides of it: It is a little verbose Developers often forget to call the HtmlEncode method New <%: %> Code Nugget Syntax With ASP.NET 4 we are introducing a new code expression syntax (<%:  %>) that renders output like <%= %> blocks do – but which also automatically HTML encodes it before doing so.  This eliminates the need to explicitly HTML encode content like we did in the example above.  Instead you can just write the more concise code below to accomplish the same thing: We chose the <%: %> syntax so that it would be easy to quickly replace existing instances of <%= %> code blocks.  It also enables you to easily search your code-base for <%= %> elements to find and verify any cases where you are not using HTML encoding within your application to ensure that you have the correct behavior. Avoiding Double Encoding While HTML encoding content is often a good best practice, there are times when the content you are outputting is meant to be HTML or is already encoded – in which case you don’t want to HTML encode it again.  ASP.NET 4 introduces a new IHtmlString interface (along with a concrete implementation: HtmlString) that you can implement on types to indicate that its value is already properly encoded (or otherwise examined) for displaying as HTML, and that therefore the value should not be HTML-encoded again.  The <%: %> code-nugget syntax checks for the presence of the IHtmlString interface and will not HTML encode the output of the code expression if its value implements this interface.  This allows developers to avoid having to decide on a per-case basis whether to use <%= %> or <%: %> code-nuggets.  Instead you can always use <%: %> code nuggets, and then have any properties or data-types that are already HTML encoded implement the IHtmlString interface. Using ASP.NET MVC HTML Helper Methods with <%: %> For a practical example of where this HTML encoding escape mechanism is useful, consider scenarios where you use HTML helper methods with ASP.NET MVC.  These helper methods typically return HTML.  For example: the Html.TextBox() helper method returns markup like <input type=”text”/>.  With ASP.NET MVC 2 these helper methods now by default return HtmlString types – which indicates that the returned string content is safe for rendering and should not be encoded by <%: %> nuggets.  This allows you to use these methods within both <%= %> code nugget blocks: As well as within <%: %> code nugget blocks: In both cases above the HTML content returned from the helper method will be rendered to the client as HTML – and the <%: %> code nugget will avoid double-encoding it. This enables you to default to always using <%: %> code nuggets instead of <%= %> code blocks within your applications.  If you want to be really hardcore you can even create a build rule that searches your application looking for <%= %> usages and flags any cases it finds as an error to enforce that HTML encoding always takes place. Scaffolding ASP.NET MVC 2 Views When you use VS 2010 (or the free Visual Web Developer 2010 Express) you’ll find that the views that are scaffolded using the “Add View” dialog now by default always use <%: %> blocks when outputting any content.  For example, below I’ve scaffolded a simple “Edit” view for an article object.  Note the three usages of <%: %> code nuggets for the label, textbox, and validation message (all output with HTML helper methods): Summary The new <%: %> syntax provides a concise way to automatically HTML encode content and then render it as output.  It allows you to make your code a little less verbose, and to easily check/verify that you are always HTML encoding content throughout your site.  This can help protect your applications against cross-site script injection (XSS) and HTML injection attacks.  Hope this helps, Scott

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• What's up with LDoms: Part 4 - Virtual Networking Explained

  - by Stefan Hinker

  I'm back from my summer break (and some pressing business that kept me away from this), ready to continue with Oracle VM Server for SPARC ;-) In this article, we'll have a closer look at virtual networking.  Basic connectivity as we've seen it in the first, simple example, is easy enough.  But there are numerous options for the virtual switches and virtual network ports, which we will discuss in more detail now.   In this section, we will concentrate on virtual networking - the capabilities of virtual switches and virtual network ports - only.  Other options involving hardware assignment or redundancy will be covered in separate sections later on. There are two basic components involved in virtual networking for LDoms: Virtual switches and virtual network devices.  The virtual switch should be seen just like a real ethernet switch.  It "runs" in the service domain and moves ethernet packets back and forth.  A virtual network device is plumbed in the guest domain.  It corresponds to a physical network device in the real world.  There, you'd be plugging a cable into the network port, and plug the other end of that cable into a switch.  In the virtual world, you do the same:  You create a virtual network device for your guest and connect it to a virtual switch in a service domain.  The result works just like in the physical world, the network device sends and receives ethernet packets, and the switch does all those things ethernet switches tend to do. If you look at the reference manual of Oracle VM Server for SPARC, there are numerous options for virtual switches and network devices.  Don't be confused, it's rather straight forward, really.  Let's start with the simple case, and work our way to some more sophisticated options later on.  In many cases, you'll want to have several guests that communicate with the outside world on the same ethernet segment.  In the real world, you'd connect each of these systems to the same ethernet switch.  So, let's do the same thing in the virtual world: root@sun # ldm add-vsw net-dev=nxge2 admin-vsw primary root@sun # ldm add-vnet admin-net admin-vsw mars root@sun # ldm add-vnet admin-net admin-vsw venus We've just created a virtual switch called "admin-vsw" and connected it to the physical device nxge2.  In the physical world, we'd have powered up our ethernet switch and installed a cable between it and our big enterprise datacenter switch.  We then created a virtual network interface for each one of the two guest systems "mars" and "venus" and connected both to that virtual switch.  They can now communicate with each other and with any system reachable via nxge2.  If primary were running Solaris 10, communication with the guests would not be possible.  This is different with Solaris 11, please see the Admin Guide for details.  Note that I've given both the vswitch and the vnet devices some sensible names, something I always recommend. Unless told otherwise, the LDoms Manager software will automatically assign MAC addresses to all network elements that need one.  It will also make sure that these MAC addresses are unique and reuse MAC addresses to play nice with all those friendly DHCP servers out there.  However, if we want to do this manually, we can also do that.  (One reason might be firewall rules that work on MAC addresses.)  So let's give mars a manually assigned MAC address: root@sun # ldm set-vnet mac-addr=0:14:4f:f9:c4:13 admin-net mars Within the guest, these virtual network devices have their own device driver.  In Solaris 10, they'd appear as "vnet0".  Solaris 11 would apply it's usual vanity naming scheme.  We can configure these interfaces just like any normal interface, give it an IP-address and configure sophisticated routing rules, just like on bare metal.  In many cases, using Jumbo Frames helps increase throughput performance.  By default, these interfaces will run with the standard ethernet MTU of 1500 bytes.  To change this,  it is usually sufficient to set the desired MTU for the virtual switch.  This will automatically set the same MTU for all vnet devices attached to that switch.  Let's change the MTU size of our admin-vsw from the example above: root@sun # ldm set-vsw mtu=9000 admin-vsw primary Note that that you can set the MTU to any value between 1500 and 16000.  Of course, whatever you set needs to be supported by the physical network, too. Another very common area of network configuration is VLAN tagging. This can be a little confusing - my advise here is to be very clear on what you want, and perhaps draw a little diagram the first few times.  As always, keeping a configuration simple will help avoid errors of all kind.  Nevertheless, VLAN tagging is very usefull to consolidate different networks onto one physical cable.  And as such, this concept needs to be carried over into the virtual world.  Enough of the introduction, here's a little diagram to help in explaining how VLANs work in LDoms: Let's remember that any VLANs not explicitly tagged have the default VLAN ID of 1. In this example, we have a vswitch connected to a physical network that carries untagged traffic (VLAN ID 1) as well as VLANs 11, 22, 33 and 44.  There might also be other VLANs on the wire, but the vswitch will ignore all those packets.  We also have two vnet devices, one for mars and one for venus.  Venus will see traffic from VLANs 33 and 44 only.  For VLAN 44, venus will need to configure a tagged interface "vnet44000".  For VLAN 33, the vswitch will untag all incoming traffic for venus, so that venus will see this as "normal" or untagged ethernet traffic.  This is very useful to simplify guest configuration and also allows venus to perform Jumpstart or AI installations over this network even if the Jumpstart or AI server is connected via VLAN 33.  Mars, on the other hand, has full access to untagged traffic from the outside world, and also to VLANs 11,22 and 33, but not 44.  On the command line, we'd do this like this: root@sun # ldm add-vsw net-dev=nxge2 pvid=1 vid=11,22,33,44 admin-vsw primary root@sun # ldm add-vnet admin-net pvid=1 vid=11,22,33 admin-vsw mars root@sun # ldm add-vnet admin-net pvid=33 vid=44 admin-vsw venus Finally, I'd like to point to a neat little option that will make your live easier in all those cases where configurations tend to change over the live of a guest system.  It's the "id=<somenumber>" option available for both vswitches and vnet devices.  Normally, Solaris in the guest would enumerate network devices sequentially.  However, it has ways of remembering this initial numbering.  This is good in the physical world.  In the virtual world, whenever you unbind (aka power off and disassemble) a guest system, remove and/or add network devices and bind the system again, chances are this numbering will change.  Configuration confusion will follow suit.  To avoid this, nail down the initial numbering by assigning each vnet device it's device-id explicitly: root@sun # ldm add-vnet admin-net id=1 admin-vsw venus Please consult the Admin Guide for details on this, and how to decipher these network ids from Solaris running in the guest. Thanks for reading this far.  Links for further reading are essentially only the Admin Guide and Reference Manual and can be found above.  I hope this is useful and, as always, I welcome any comments.

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• Prioritizing Product Features

  - by Robert May

  A very common task in Agile Environments is prioritization.  Teams that are functioning well will prioritize new features, old features, the backlog, and any other source of stories for the team, and they’ll do it regularly. Not all teams are good at prioritizing according to the real return on investment that building stories will yield to the company.  This is unfortunate.  Too often, teams end up building features that are less valuable, and everyone seems to know it except perhaps the product owner!  Most features built into software are never even used.  Clearly, not much return for features that go unused. So how does a company avoid building features that add little value to the company?  This is a tough question to answer, but usually, this prioritization starts at the top with the executives of the company.  After all, they’re responsible for the overall vision of the company. Here’s what I recommend: Know your market. Know your customers and users. Know where you’re going and what you want to achieve. Implement the Vision Know Your Market We often see companies that don’t know their market.  Personally, I’m surprised by this.  These companies don’t know who their competitors are, don’t know what features make their product desirable in the market, and in many cases, get by with saying, “I’ve been doing this for XX years.  I know what the market wants!”  In many cases, they equate “marketing” with “advertising” and don’t understand the difference. This is almost never true.  Good companies will spend significant amounts of time and money finding out who they’re competing against and what makes their competitors successful in the marketplace.  Good companies understand that marketing involves more than just advertising.  Often, marketing is mostly research and analysis, not sales.  Until you understand your market, you cannot know what features will give you the best return on your investment dollar. Good companies have a marketing department and can answer the next important step which is to know your customers and your users. Know your Customers and Users First, note that I included both customers and users.  They’re often not the same thing.  Users use the product that you build.  Customers buy the product that you build.  It’s a subtle difference, but too often, I’ve seen companies that focus exclusively on one or the other and are not successful simply because they ignore an important part of the group. If your company is doing appropriate marketing, you know that these are two different aspects of your product and that both deserve attention to have a product that is successful in your target market.  Your marketing department should be spending a lot of time understanding these personas and then conveying that information to the company. I’m always surprised when development teams think that they can build a product that people want to use without understanding the users of that product.  Developers think differently than most people in the world.  They know what the computer is doing.  The computer isn’t magic to them.  So when they assume that they know how to build something, they bring with them quite a bit of baggage.  Never assume that you know your customer unless you’re regularly having interaction with them.  Also, don’t just leave this to Marketing or Product Management.  Take them time to get your developers out with the customers as well.  Developers are very smart people, and often, seeing how someone uses their software inspires them to make a much better product. Very often, because the users and customers aren’t know, teams will spend a significant amount of time building apps that are super flexible and configurable so that any possible combination of feature can be used.  This demonstrates a clear lack of understanding of the customer.  Most configuration questions can quickly be answered by talking to the customer.  In most cases, if your software requires significant setup and configuration before its usable, you probably don’t know your customers and users very well. Until you know your customers, you cannot know what features will be most valuable to your customers and you cannot build those features in a way that your customers can use. Know Where You’re Going and What You Want to Achieve Many companies suffer from not having a plan.  Executives will tell the team to make them a plan.  The team, not knowing their market and customers and users, will come up with a plan that doesn’t reflect reality and doesn’t consider ROI.  Management then wonders why the product is doing poorly in the market place. Instead of leaving this up to the teams, as executives, work with Marketing to understand what broad categories of features will sell the most product in the marketplace.  Then, once you’ve determined that, give this vision to the team and let them run with it.  Revise the vision as needed, but avoid changing streams frequently.  Sure, sometimes you need to, but often, executives will change priorities many times a month, leading to nothing more than confusion.  If the team has a vision, they’ll be able to execute that vision far better than they could otherwise. By knowing what products are most important, you can set budgetary goals and guidelines that will help you achieve the vision that was created. Implement the Vision Creating the vision is often where the general executives stop participating in the plan.  The team is responsible for implementing that vision.  Executives should attend showcases and and should remain aware of the progress that the team is making towards meeting the vision, however. Once a broad vision has been created, the team should break that vision down into minimal market features (MMF).  These MMFs should be sized using story points so that, using the team’s velocity, an estimated cost can be determined for each feature.  The product management team should then try to quantify the relative value of the MMFs based on customer feedback and interviews.  Once the value and cost of creating the feature is understood, a return on investment can be calculated.  The features should then be prioritized with the MMF’s that have the highest value and lowest cost rising to the top of features to implement.  Don’t let politics get in the way! Once the MMF’s have been prioritized, they should go through release planning to schedule them for implementation. Conclusion By having a good grasp on the strategy of the company, your Agile teams can be much more effective.  Each and every story the team is implementing will roll up into features that matter to the company and provide ROI to them.  The steps outlined in this post should be repeated on a regular basis.  I recommend reviewing them at least once per quarter to make sure that the vision hasn’t shifted and that the teams are still working on what matters most to the company. Technorati Tags: Agile,Product Owner,ROI

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• WP7 Tips–Part I– Media File Coding Techniques to help pass the Windows Phone 7 Marketplace Certification Requirements

  - by seaniannuzzi

  Overview Developing an application that plays media files on a Windows Phone 7 Device seems fairly straight forward.  However, what can make this a bit frustrating are the necessary requirements in order to pass the WP7 marketplace requirements so that your application can be published.  If you are new to this development, be aware of these common challenges that are likely to be made.  Below are some techniques and recommendations on how optimize your application to handle playing MP3 and/or WMA files that needs to adhere to the marketplace requirements.   Windows Phone 7 Certification Requirements Windows Phone 7 Developers Blog   Some common challenges are: Not prompting the user if another media file is playing in the background before playing your media file Not allowing the user to control the volume Not allowing the user to mute the sound Not allowing the media to be interrupted by a phone call  To keep this as simple as possible I am only going to focus on what “not to do” and what “to do” in order to implement a simple media solution. Things you will need or may be useful to you before you begin: Visual Studio 2010 Visual Studio 2010 Feature Packs Windows Phone 7 Developer Tools Visual Studio 2010 Express for Windows Phone Windows Phone Emulator Resources Silverlight 4 Tools For Visual Studio XNA Game Studio 4.0 Microsoft Expression Blend for Windows Phone Note: Please keep in mind you do not need all of these downloaded and installed, it is just easier to have all that you need now rather than add them on later.   Objective Summary Create a Windows Phone 7 – Windows Media Sample Application.  The application will implement many of the required features in order to pass the WP7 marketplace certification requirements in order to publish an application to WP7’s marketplace. (Disclaimer: I am not trying to indicate that this application will always pass as the requirements may change or be updated)   Step 1: – Create a New Windows Phone 7 Project   Step 2: – Update the Title and Application Name of your WP7 Application For this example I changed: the Title to: “DOTNETNUZZI WP7 MEDIA SAMPLE - v1.00” and the Page Title to:  “media magic”. Note: I also updated the background.   Step 3: – XAML - Media Element Preparation and Best Practice Before we begin the next step I just wanted to point out a few things that you should not do as a best practice when developing an application for WP7 that is playing music.  Please keep in mind that these requirements are not the same if you are playing Sound Effects and are geared towards playing media in the background.   If you have coded this – be prepared to change it:   To avoid a failure from the market place remove all of your media source elements from your XAML or simply create them dynamically.  To keep this simple we will remove the source and set the AutoPlay property to false to ensure that there are no media elements are active when the application is started. Proper example of the media element with No Source:   Some Additional Settings - Add XAML Support for a Mute Button   Step 4: – Boolean to handle toggle of Mute Feature Step 5: – Add Event Handler for Main Page Load   Step 6: – Add Reference to the XNA Framework   Step 7: – Add two Using Statements to Resolve the Namespace of Media and the Application Bar using Microsoft.Xna.Framework.Media; using Microsoft.Phone.Shell;   Step 8: – Add the Method to Check the Media State as Shown Below   Step 9: – Add Code to Mute the Media File Step 10: – Add Code to Play the Media File //if the state of the media has been checked you are good to go. media_sample.Play(); Note: If we tried to perform this operation at this point you will receive the following error: System.InvalidOperationException was unhandled Message=FrameworkDispatcher.Update has not been called. Regular FrameworkDispatcher.Update calls are necessary for fire and forget sound effects and framework events to function correctly. See http://go.microsoft.com/fwlink/?LinkId=193853 for details. StackTrace:        at Microsoft.Xna.Framework.FrameworkDispatcher.AddNewPendingCall(ManagedCallType callType, UInt32 arg)        at Microsoft.Xna.Framework.UserAsyncDispatcher.HandleManagedCallback(ManagedCallType managedCallType, UInt32 managedCallArgs) at Microsoft.Xna.Framework.UserAsyncDispatcher.AsyncDispatcherThreadFunction()            It is not recommended that you just add the FrameworkDispatcher.Update(); call before playing the media file. It is recommended that you implement the following class to your solution and implement this class in the app.xaml.cs file.   Step 11: – Add FrameworkDispatcher Features I recommend creating a class named XNAAsyncDispatcher and adding the following code:   After you have added the code accordingly, you can now implement this into your app.xaml.cs file as highlighted below.   Note:  If you application sound file is not playing make sure you have the proper “Build Action” set such as Content.   Running the Sample Now that we have some of the foundation created you should be able to run the application successfully.  When the application launches your sound options should be set accordingly when the “checkMediaState” method is called.  As a result the application will properly setup the media options and/or alert the user accordinglyper the certification requirements.  In addition, the sample also shows a quick way to mute the sound in your application by simply removing the URI source of the media file.  If everything successfully compiled the application should look similar to below.                 <sound playing>   Summary At this point we have a fully functional application that provides techniques on how to avoid some common challenges when working with media files and developing applications for Windows Phone 7.  The techniques mentioned above should make things a little easier and helpful in getting your WP7 application approved and published on the Marketplace.  The next blog post will be titled: WP7 Tips–Part II - How to write code that will pass the Windows Phone 7 Marketplace Requirements for Themes (light and dark). If anyone has any questions or comments please comment on this blog. 

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• Time Tracking on an Agile Team

  - by Stephen.Walther

  What’s the best way to handle time-tracking on an Agile team? Your gut reaction to this question might be to resist any type of time-tracking at all. After all, one of the principles of the Agile Manifesto is “Individuals and interactions over processes and tools”.  Forcing the developers on your team to track the amount of time that they devote to completing stories or tasks might seem like useless bureaucratic red tape: an impediment to getting real work done. I completely understand this reaction. I’ve been required to use time-tracking software in the past to account for each hour of my workday. It made me feel like Fred Flintstone punching in at the quarry mine and not like a professional. Why You Really Do Need Time-Tracking There are, however, legitimate reasons to track time spent on stories even when you are a member of an Agile team.  First, if you are working with an outside client, you might need to track the number of hours spent on different stories for the purposes of billing. There might be no way to avoid time-tracking if you want to get paid. Second, the Product Owner needs to know when the work on a story has gone over the original time estimated for the story. The Product Owner is concerned with Return On Investment. If the team has gone massively overtime on a story, then the Product Owner has a legitimate reason to halt work on the story and reconsider the story’s business value. Finally, you might want to track how much time your team spends on different types of stories or tasks. For example, if your team is spending 75% of their time doing testing then you might need to bring in more testers. Or, if 10% of your team’s time is expended performing a software build at the end of each iteration then it is time to consider better ways of automating the build process. Time-Tracking in SonicAgile For these reasons, we added time-tracking as a feature to SonicAgile which is our free Agile Project Management tool. We were heavily influenced by Jeff Sutherland (one of the founders of Scrum) in the way that we implemented time-tracking (see his article http://scrum.jeffsutherland.com/2007/03/time-tracking-is-anti-scrum-what-do-you.html). In SonicAgile, time-tracking is disabled by default. If you want to use this feature then the project owner must enable time-tracking in Project Settings. You can choose to estimate using either days or hours. If you are estimating at the level of stories then it makes more sense to choose days. Otherwise, if you are estimating at the level of tasks then it makes more sense to use hours. After you enable time-tracking then you can assign three estimates to a story: Original Estimate – This is the estimate that you enter when you first create a story. You don’t change this estimate. Time Spent – This is the amount of time that you have already devoted to the story. You update the time spent on each story during your daily standup meeting. Time Left – This is the amount of time remaining to complete the story. Again, you update the time left during your daily standup meeting. So when you first create a story, you enter an original estimate that becomes the time left. During each daily standup meeting, you update the time spent and time left for each story on the Kanban. If you had perfect predicative power, then the original estimate would always be the same as the sum of the time spent and the time left. For example, if you predict that a story will take 5 days to complete then on day 3, the story should have 3 days spent and 2 days left. Unfortunately, never in the history of mankind has anyone accurately predicted the exact amount of time that it takes to complete a story. For this reason, SonicAgile does not update the time spent and time left automatically. Each day, during the daily standup, your team should update the time spent and time left for each story. For example, the following table shows the history of the time estimates for a story that was originally estimated to take 3 days but, eventually, takes 5 days to complete: Day Original Estimate Time Spent Time Left Day 1 3 days 0 days 3 days Day 2 3 days 1 day 2 days Day 3 3 days 2 days 2 days Day 4 3 days 3 days 2 days Day 5 3 days 4 days 0 days In the table above, everything goes as predicted until you reach day 3. On day 3, the team realizes that the work will require an additional two days. The situation does not improve on day 4. All of the sudden, on day 5, all of the remaining work gets done. Real work often follows this pattern. There are long periods when nothing gets done punctuated by occasional and unpredictable bursts of progress. We designed SonicAgile to make it as easy as possible to track the time spent and time left on a story. Detecting when a Story Goes Over the Original Estimate Sometimes, stories take much longer than originally estimated. There’s a surprise. For example, you discover that a new software component is incompatible with existing software components. Or, you discover that you have to go through a month-long certification process to finish a story. In those cases, the Product Owner has a legitimate reason to halt work on a story and re-evaluate the business value of the story. For example, the Product Owner discovers that a story will require weeks to implement instead of days, then the story might not be worth the expense. SonicAgile displays a warning on both the Backlog and the Kanban when the time spent on a story goes over the original estimate. An icon of a clock is displayed. Time-Tracking and Tasks Another optional feature of SonicAgile is tasks. If you enable Tasks in Project Settings then you can break stories into one or more tasks. You can perform time-tracking at the level of a story or at the level of a task. If you don’t break a story into tasks then you can enter the time left and time spent for the story. As soon as you break a story into tasks, then you can no longer enter the time left and time spent at the level of the story. Instead, the time left and time spent for a story is rolled up from its tasks. On the Kanban, you can see how the time left and time spent for each task gets rolled up into each story. The progress bar for the story is rolled up from the progress bars for each task. The original estimate is never rolled up – even when you break a story into tasks. A story’s original estimate is entered separately from the original estimates of each of the story’s tasks. Summary Not every Agile team can avoid time-tracking. You might be forced to track time to get paid, to detect when you are spending too much time on a particular story, or to track the amount of time that you are devoting to different types of tasks. We designed time-tracking in SonicAgile to require the least amount of work to track the information that you need. Time-tracking is an optional feature. If you enable time-tracking then you can track the original estimate, time left, and time spent for each story and task. You can use time-tracking with SonicAgile for free. Register at http://SonicAgile.com.

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• SQL SERVER – SSMS Automatically Generates TOP (100) PERCENT in Query Designer

  - by pinaldave

  Earlier this week, I was surfing various SQL forums to see what kind of help developer need in the SQL Server world. One of the question indeed caught my attention. I am here regenerating complete question as well scenario to illustrate the point in a precise manner. Additionally, I have added added second part of the question to give completeness. Question: I am trying to create a view in Query Designer (not in the New Query Window). Every time I am trying to create a view it always adds  TOP (100) PERCENT automatically on the T-SQL script. No matter what I do, it always automatically adds the TOP (100) PERCENT to the script. I have attempted to copy paste from notepad, build a query and a few other things – there is no success. I am really not sure what I am doing wrong with Query Designer. Here is my query script: (I use AdventureWorks as a sample database) SELECT Person.Address.AddressID FROM Person.Address INNER JOIN Person.AddressType ON Person.Address.AddressID = Person.AddressType.AddressTypeID ORDER BY Person.Address.AddressID This script automatically replaces by following query: SELECT TOP (100) PERCENT Person.Address.AddressID FROM Person.Address INNER JOIN Person.AddressType ON Person.Address.AddressID = Person.AddressType.AddressTypeID ORDER BY Person.Address.AddressID However, when I try to do the same from New Query Window it works totally fine. However, when I attempt to create a view of the same query it gives following error. Msg 1033, Level 15, State 1, Procedure myView, Line 6 The ORDER BY clause is invalid in views, inline functions, derived tables, subqueries, and common table expressions, unless TOP, OFFSET or FOR XML is also specified. It is pretty clear to me now that the script which I have written seems to need TOP (100) PERCENT, so Query . Why do I need it? Is there any work around to this issue. I particularly find this question pretty interesting as it really touches the fundamentals of the T-SQL query writing. Please note that the query which is automatically changed is not in New Query Editor but opened from SSMS using following way. Database >> Views >> Right Click >> New View (see the image below) Answer: The answer to the above question can be very long but I will keep it simple and to the point. There are three things to discuss in above script 1) Reason for Error 2) Reason for Auto generates TOP (100) PERCENT and 3) Potential solutions to the above error. Let us quickly see them in detail. 1) Reason for Error The reason for error is already given in the error. ORDER BY is invalid in the views and a few other objects. One has to use TOP or other keywords along with it. The way semantics of the query works where optimizer only follows(honors) the ORDER BY in the same scope or the same SELECT/UPDATE/DELETE statement. There is a possibility that one can order after the scope of the view again the efforts spend to order view will be wasted. The final resultset of the query always follows the final ORDER BY or outer query’s order and due to the same reason optimizer follows the final order of the query and not of the views (as view will be used in another query for further processing e.g. in SELECT statement). Due to same reason ORDER BY is now allowed in the view. For further accuracy and clear guidance I suggest you read this blog post by Query Optimizer Team. They have explained it very clear manner the same subject. 2) Reason for Auto Generated TOP (100) PERCENT One of the most popular workaround to above error is to use TOP (100) PERCENT in the view. Now TOP (100) PERCENT allows user to use ORDER BY in the query and allows user to overcome above error which we discussed. This gives the impression to the user that they have resolved the error and successfully able to use ORDER BY in the View. Well, this is incorrect as well. The way this works is when TOP (100) PERCENT is used the result is not guaranteed as well it is ignored in our the query where the view is used. Here is the blog post on this subject: Interesting Observation – TOP 100 PERCENT and ORDER BY. Now when you create a new view in the SSMS and build a query with ORDER BY to avoid the error automatically it adds the TOP 100 PERCENT. Here is the connect item for the same issue. I am sure there will be more connect items as well but I could not find them. 3) Potential Solutions If you are reading this post from the beginning in that case, it is clear by now that ORDER BY should not be used in the View as it does not serve any purpose unless there is a specific need of it. If you are going to use TOP 100 PERCENT with ORDER BY there is absolutely no need of using ORDER BY rather avoid using it all together. Here is another blog post of mine which describes the same subject ORDER BY Does Not Work – Limitation of the Views Part 1. It is valid to use ORDER BY in a view if there is a clear business need of using TOP with any other percentage lower than 100 (for example TOP 10 PERCENT or TOP 50 PERCENT etc). In most of the cases ORDER BY is not needed in the view and it should be used in the most outer query for present result in desired order. User can remove TOP 100 PERCENT and ORDER BY from the view before using the view in any query or procedure. In the most outer query there should be ORDER BY as per the business need. I think this sums up the concept in a few words. This is a very long topic and not easy to illustrate in one single blog post. I welcome your comments and suggestions. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, SQL View, T SQL, Technology

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• tile_static, tile_barrier, and tiled matrix multiplication with C++ AMP

  - by Daniel Moth

  We ended the previous post with a mechanical transformation of the C++ AMP matrix multiplication example to the tiled model and in the process introduced tiled_index and tiled_grid. This is part 2. tile_static memory You all know that in regular CPU code, static variables have the same value regardless of which thread accesses the static variable. This is in contrast with non-static local variables, where each thread has its own copy. Back to C++ AMP, the same rules apply and each thread has its own value for local variables in your lambda, whereas all threads see the same global memory, which is the data they have access to via the array and array_view. In addition, on an accelerator like the GPU, there is a programmable cache, a third kind of memory type if you'd like to think of it that way (some call it shared memory, others call it scratchpad memory). Variables stored in that memory share the same value for every thread in the same tile. So, when you use the tiled model, you can have variables where each thread in the same tile sees the same value for that variable, that threads from other tiles do not. The new storage class for local variables introduced for this purpose is called tile_static. You can only use tile_static in restrict(direct3d) functions, and only when explicitly using the tiled model. What this looks like in code should be no surprise, but here is a snippet to confirm your mental image, using a good old regular C array // each tile of threads has its own copy of locA, // shared among the threads of the tile tile_static float locA[16][16]; Note that tile_static variables are scoped and have the lifetime of the tile, and they cannot have constructors or destructors. tile_barrier In amp.h one of the types introduced is tile_barrier. You cannot construct this object yourself (although if you had one, you could use a copy constructor to create another one). So how do you get one of these? You get it, from a tiled_index object. Beyond the 4 properties returning index objects, tiled_index has another property, barrier, that returns a tile_barrier object. The tile_barrier class exposes a single member, the method wait. 15: // Given a tiled_index object named t_idx 16: t_idx.barrier.wait(); 17: // more code …in the code above, all threads in the tile will reach line 16 before a single one progresses to line 17. Note that all threads must be able to reach the barrier, i.e. if you had branchy code in such a way which meant that there is a chance that not all threads could reach line 16, then the code above would be illegal. Tiled Matrix Multiplication Example – part 2 So now that we added to our understanding the concepts of tile_static and tile_barrier, let me obfuscate rewrite the matrix multiplication code so that it takes advantage of tiling. Before you start reading this, I suggest you get a cup of your favorite non-alcoholic beverage to enjoy while you try to fully understand the code. 01: void MatrixMultiplyTiled(vector<float>& vC, const vector<float>& vA, const vector<float>& vB, int M, int N, int W) 02: { 03: static const int TS = 16; 04: array_view<const float,2> a(M, W, vA); 05: array_view<const float,2> b(W, N, vB); 06: array_view<writeonly<float>,2> c(M,N,vC); 07: parallel_for_each(c.grid.tile< TS, TS >(), 08: [=] (tiled_index< TS, TS> t_idx) restrict(direct3d) 09: { 10: int row = t_idx.local[0]; int col = t_idx.local[1]; 11: float sum = 0.0f; 12: for (int i = 0; i < W; i += TS) { 13: tile_static float locA[TS][TS], locB[TS][TS]; 14: locA[row][col] = a(t_idx.global[0], col + i); 15: locB[row][col] = b(row + i, t_idx.global[1]); 16: t_idx.barrier.wait(); 17: for (int k = 0; k < TS; k++) 18: sum += locA[row][k] * locB[k][col]; 19: t_idx.barrier.wait(); 20: } 21: c[t_idx.global] = sum; 22: }); 23: } Notice that all the code up to line 9 is the same as per the changes we made in part 1 of tiling introduction. If you squint, the body of the lambda itself preserves the original algorithm on lines 10, 11, and 17, 18, and 21. The difference being that those lines use new indexing and the tile_static arrays; the tile_static arrays are declared and initialized on the brand new lines 13-15. On those lines we copy from the global memory represented by the array_view objects (a and b), to the tile_static vanilla arrays (locA and locB) – we are copying enough to fit a tile. Because in the code that follows on line 18 we expect the data for this tile to be in the tile_static storage, we need to synchronize the threads within each tile with a barrier, which we do on line 16 (to avoid accessing uninitialized memory on line 18). We also need to synchronize the threads within a tile on line 19, again to avoid the race between lines 14, 15 (retrieving the next set of data for each tile and overwriting the previous set) and line 18 (not being done processing the previous set of data). Luckily, as part of the awesome C++ AMP debugger in Visual Studio there is an option that helps you find such races, but that is a story for another blog post another time. May I suggest reading the next section, and then coming back to re-read and walk through this code with pen and paper to really grok what is going on, if you haven't already? Cool. Why would I introduce this tiling complexity into my code? Funny you should ask that, I was just about to tell you. There is only one reason we tiled our extent, had to deal with finding a good tile size, ensure the number of threads we schedule are correctly divisible with the tile size, had to use a tiled_index instead of a normal index, and had to understand tile_barrier and to figure out where we need to use it, and double the size of our lambda in terms of lines of code: the reason is to be able to use tile_static memory. Why do we want to use tile_static memory? Because accessing tile_static memory is around 10 times faster than accessing the global memory on an accelerator like the GPU, e.g. in the code above, if you can get 150GB/second accessing data from the array_view a, you can get 1500GB/second accessing the tile_static array locA. And since by definition you are dealing with really large data sets, the savings really pay off. We have seen tiled implementations being twice as fast as their non-tiled counterparts. Now, some algorithms will not have performance benefits from tiling (and in fact may deteriorate), e.g. algorithms that require you to go only once to global memory will not benefit from tiling, since with tiling you already have to fetch the data once from global memory! Other algorithms may benefit, but you may decide that you are happy with your code being 150 times faster than the serial-version you had, and you do not need to invest to make it 250 times faster. Also algorithms with more than 3 dimensions, which C++ AMP supports in the non-tiled model, cannot be tiled. Also note that in future releases, we may invest in making the non-tiled model, which already uses tiling under the covers, go the extra step and use tile_static memory on your behalf, but it is obviously way to early to commit to anything like that, and we certainly don't do any of that today. Comments about this post by Daniel Moth welcome at the original blog.

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• H1 Visa interview tips–What you must know before attending the interview?

  - by Gopinath

  USA’s H1 visa allows highly qualified professionals from other countries to work in America. Many IT professionals in India aspire to go to USA on H1 and work for their clients. Recently I had a chance to study H1 visa process to help one of my friends and I would like to share what I learned. With the assumption that your H1 petition is approved and you got an interview scheduled at US Embassy for your visa stamping, here are tips you must know before attending the interview Dress Code – Formals Say no to casuals or any fancy dress when you attend the interview. It’s not a party or friends home you are visiting. Consider H1 Visa interview as your job interview and dress up in formals. There is no option B for your, you must be in formals. A plain formal shirt with a matching pant is suggested for men. Tie and Suit would not be required, but if you are a professional at management level you can consider wearing suit. Women can wear either formal Salwar or formal pant-shirt. Avoid heavy jewellery, wear what is must as per your tradition or culture. Body Language -  Smile on your face Your body language reflects what you are and what’s going on in your mind. Don’t be nervous or restless, be relaxed and wear a beautiful smile on your face. A smile is a curve that sets everything straight. When you are called for the interview, greet the interviewer with a beautiful smile. Say Good Morning/Afternoon/Evening depending on time you are visiting them. Whenever appropriate say Thank You. Generally American professionals are very friendly people and they reciprocate for your greetings. Make sure that you make them comfortable to start the interview. Carry original documents in a separate folder I don’t want to talk much about the documents that are required for your H1B interview as it’s big subject on it’s own and it requires a separate post. I assume that your consultant or employer helped you in gathering all the required documents like – petition, DS 160 forms, education & job related documents, resume, interview call letters, client letters, etc. For all the documents you are going to submit at the interview make sure that you have originals in a separate folder.  If required interviewer may ask you show the originals of any of the document you submitted for visa processing. Don’t mix the original documents with the documents you need to submit for interview. Have a separate folder for them. For those who are going to stamping along with their spouse and children, they need to carry few extra original documents like – marriage certificate, marriage photos(30 numbers)/album, birth certificates, passports, education and profession related certificates of the spouse and children. Know your role & responsibilities The interviewer will ask you questions on your roles and responsibilities at client location. Be clear what is your day to day tasks at client place and prepared to face detailed questions on the same. When asked explain clearly and also make sure what you say is inline with what is mentioned in your petition and client invitation letter. At times they may ask you questions specific to the project/technology you are going to work. So doing some homework in this area will help you easily answer the questions. Failing to answer basic questions on your role & responsibilities may result in rejection. You work for your Employer at Client location but NOT FOR CLIENT One of the important things to keep in mind that you work for your employer and you are being deputed to client location on a work visa.  Your employer is going to be solely responsible for your salary, work, promotion, pay hikes or what so ever during your stay at USA. Your client will not be responsible for anything. Lets say you are employed with Company X in India and they are applying for H1B to work at your client(ex: Microsoft) in USA, you must keep in my mind that Microsoft is not your employer. Microsoft will not pay your salaries or responsible for any employment related activities. Company X will be solely responsible for all your employer related activities. If you don’t get this correctly and say to Visa interviewer that your client is responsible, then you may get into troubles. Know your client It’s always good to know the clients with whom you are going to work in USA and their business. If your client is a well know organisation then you may not get many questions from interviewer else you need to be well prepared to provide details like – nature of business, location, size of the organisation, etc.  Get to know the basic details about your client and be confident while providing those details to the interviewer. Also make sure that you never talk about any confidential details of your client projects and business. Revealing confidential details of your client may land your job itself in soup. Make sure that your spouse is also in sync with you If you’ve applied a H4 visa for your spouse along with your H1, make sure that spouse is in sync with you. Your spouse also should know the basic details of your job, your employer, client and location where you will be travelling. Your spouse should also be prepared to answers questions related to marriage, their profession(if working), kids, education, etc. Interviewers will try to asses your spouse communication skills, whereabouts while staying in USA and would they prefer to work USA or not. On H4, which is a dependent visa, your spouse is not allowed to work in USA and at any point your spouse should not show the intentions to search for work in USA. Less luggage more comfort You would have definitely heard that there are lot of restrictions on what you can carry along with you to an US Embassy while attending the interview. To be frank it’s not good to say there are many restrictions, but there are a hell a lot of restrictions. There are unbelievable restrictions and it’s for the safety of everyone. You are not allowed to carry mobile phones, CD/DVDs, USBs, bank cards, cameras, cosmetics, food(except baby food), water, wallets, backpacks, sealed covers, etc. Trust me most of the things we carry with us regularly every day are not allowed inside. As there are 100s of restrictions, it would be easier if you understand what you can carry along with you and just carry them alone. Ask your employer/consultant to provide you a checklist of items that you can carry. Most what you would require are H1B related documents provided by the employer/consultant Photographs All original documents supporting your H1B Passports Some cash for your travel expenses (avoid coins) Any important phone number / details written in a paper(like your cab driver number, etc.) If you carry restricted stuff then you will be stopped at security checks, you have to find people who can safely keep all the restricted items. Due to heavy restrictions in and around the US Embassy you will not find any  place to keep your luggage. So just carry the bare minimum things required so that you feel more comfortable. Useful Links THE U.S. NON IMMIGRANT VISA APPLICATION PROCESS U.S VISA SECURITY REGULATIONS GENERAL FAQS Hope this information is helpful to you and best of luck for your interview. Creative commons Image credit: Flickr/ alexfrance, vinothchandar. hughelectronic, architratan, striatic

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• CodePlex Daily Summary for Sunday, August 03, 2014

  CodePlex Daily Summary for Sunday, August 03, 2014Popular ReleasesBoxStarter: Boxstarter 2.4.76: Running the Setup.bat file will install Chocolatey if not present and then install the Boxstarter modules.GMare: GMare Beta 1.2: Features Added: - Instance painting by holding the alt key down while pressing the left mouse button - Functionality to the binary exporter so that backgrounds from image files can be used - On the binary exporter background information can be edited manually now - Update to the GMare binary read GML script - Game Maker Studio export - Import from GMare project. Multiple options to import desired properties of a .gmpx - 10 undo/redo levels instead of 5 is now the default - New preferences dia...Json.NET: Json.NET 6.0 Release 4: New feature - Added Merge to LINQ to JSON New feature - Added JValue.CreateNull and JValue.CreateUndefined New feature - Added Windows Phone 8.1 support to .NET 4.0 portable assembly New feature - Added OverrideCreator to JsonObjectContract New feature - Added support for overriding the creation of interfaces and abstract types New feature - Added support for reading UUID BSON binary values as a Guid New feature - Added MetadataPropertyHandling.Ignore New feature - Improv...SQL Server Dialog: SQL Server Dialog: Input server, user and password Show folder and file in treeview Customize icon Filter file extension Skip system generate folder and fileAitso-a platform for spatial optimization and based on artificial immune systems: Aitso_0.14.08.01: Aitso0.14.08.01Installer.zipVidCoder: 1.5.24 Beta: Added NL-Means denoiser. Updated HandBrake core to SVN 6254. Added extra error handling to DVD player code to avoid a crash when the player was moved.AutoUpdater.NET : Auto update library for VB.NET and C# Developer: AutoUpdater.NET 1.3: Fixed problem in DownloadUpdateDialog where download continues even if you close the dialog. Added support for new url field for 64 bit application setup. AutoUpdater.NET will decide which download url to use by looking at the value of IntPtr.Size. Added German translation provided by Rene Kannegiesser. Now developer can handle update logic herself using event suggested by ricorx7. Added italian translation provided by Gianluca Mariani. Fixed bug that prevents Application from exiti...SEToolbox: SEToolbox 01.041.012 Release 1: Added voxel material textures to read in with mods. Fixed missing texture replacements for mods. Fixed rounding issue in raytrace code. Fixed repair issue with corrupt checkpoint file. Fixed issue with updated SE binaries 01.041.012 using new container configuration.Magick.NET: Magick.NET 6.8.9.601: Magick.NET linked with ImageMagick 6.8.9.6 Breaking changes: - Changed arguments for the Map method of MagickImage. - QuantizeSettings uses Riemersma by default.Multiple Threads TCP Server: Project: this Project is based on VS 2013, .net freamwork 4.0, you can open it by vs 2010 or laterAricie Shared: Aricie.Shared Version 1.8.00: Version 1.8.0 - Release Notes New: Expression Builder to design Flee Expressions New: Cryptographic helpers and configuration classes Improvement: Many fixes and improvements with property editor Improvement: Token Replace Property explorer now has a restricted mode for additional security Improvement: Better variables, types and object manipulation Fixed: smart file and flee bugs Fixed: Removed Exception while trying to read unsuported files Improvement: several performance twe...Accesorios de sitios Torrent en Español para Synology Download Station: Pack de Torrents en Español 6.0.0: Agregado los módulos de DivXTotal, el módulo de búsqueda depende del de alojamiento para bajar las series Utiliza el rss: http://www.divxtotal.com/rss.php DbEntry.Net (Leafing Framework): DbEntry.Net 4.2: DbEntry.Net is a lightweight Object Relational Mapping (ORM) database access compnent for .Net 4.0+. It has clearly and easily programing interface for ORM and sql directly, and supoorted Access, Sql Server, MySql, SQLite, Firebird, PostgreSQL and Oracle. It also provide a Ruby On Rails style MVC framework. Asp.Net DataSource and a simple IoC. DbEntry.Net.v4.2.Setup.zip include the setup package. DbEntry.Net.v4.2.Src.zip include source files and unit tests. DbEntry.Net.v4.2.Samples.zip ...Azure Storage Explorer: Azure Storage Explorer 6 Preview 1: Welcome to Azure Storage Explorer 6 Preview 1 This is the first release of the latest Azure Storage Explorer, code-named Phoenix. What's New?Here are some important things to know about version 6: Open Source Now being run as a full open source project. Full source code on CodePlex. Collaboration encouraged! Updated Code Base Brand-new code base (WPF/C#/.NET 4.5) Visual Studio 2013 solution (previously VS2010) Uses the Task Parallel Library (TPL) for asynchronous background operat...Wsus Package Publisher: release v1.3.1407.29: Updated WPP to recognize the very latest console version. Some files was missing into the latest release of WPP which lead to crash when trying to make a custom update. Add a workaround to avoid clipboard modification when double-clicking on a label when creating a custom update. Add the ability to publish detectoids. (This feature is still in a BETA phase. Packages relying on these detectoids to determine which computers need to be updated, may apply to all computers).VG-Ripper & PG-Ripper: PG-Ripper 1.4.32: changes NEW: Added Support for 'ImgMega.com' links NEW: Added Support for 'ImgCandy.net' links NEW: Added Support for 'ImgPit.com' links NEW: Added Support for 'Img.yt' links FIXED: 'Radikal.ru' links FIXED: 'ImageTeam.org' links FIXED: 'ImgSee.com' links FIXED: 'Img.yt' linksAsp.Net MVC-4,Entity Framework and JQGrid Demo with Todo List WebApplication: Asp.Net MVC-4,Entity Framework and JQGrid Demo: Asp.Net MVC-4,Entity Framework and JQGrid Demo with simple Todo List WebApplication, Overview TodoList is a simple web application to create, store and modify Todo tasks to be maintained by the users, which comprises of following fields to the user (Task Name, Task Description, Severity, Target Date, Task Status). TodoList web application is created using MVC - 4 architecture, code-first Entity Framework (ORM) and Jqgrid for displaying the data.Waterfox: Waterfox 31.0 Portable: New features in Waterfox 31.0: Added support for Unicode 7.0 Experimental support for WebCL New features in Firefox 31.0:New Add the search field to the new tab page Support of Prefer:Safe http header for parental control mozilla::pkix as default certificate verifier Block malware from downloaded files Block malware from downloaded files audio/video .ogg and .pdf files handled by Firefox if no application specified Changed Removal of the CAPS infrastructure for specifying site-sp...SuperSocket, an extensible socket server framework: SuperSocket 1.6.3: The changes below are included in this release: fixed an exception when collect a server's status but it has been stopped fixed a bug that can cause an exception in case of sending data when the connection dropped already fixed the log4net missing issue for a QuickStart project fixed a warning in a QuickStart projectYnote Classic: Ynote Classic 2.8.5 Beta: Several Changes - Multiple Carets and Multiple Selections - Improved Startup Time - Improved Syntax Highlighting - Search Improvements - Shell Command - Improved StabilityNew ProjectsCreek: Creek is a Collection of many C# Frameworks and my ownSpeaking Speedometer (android): Simple speaking speedometerT125Protocol { Alpha version }: implement T125 Protocol for communicate with a mainframe.Unix Time: This library provides a System.UnixTime as a new Type providing conversion between Unix Time and .NET DateTime.

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