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  • Good resource for studying Database High Availability techniques

    - by Invincible
    Hello Can anybody suggest some good resource/book on Database high availability techniques? Moreover, High-availability of system software like Intrusion Prevention system or Web servers. I am considering high-availability is global term which covers clustring, cloud computing, replication, replica management, distributed synchronization for cluster. Thanks in advance!

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  • Is it faster to compute values in a query, call a Scalar Function (decimal(28,2) datatype) 4 times,

    - by Pulsehead
    I have a handful of queries I need to write in SQL Server 2005. Each Query will be calculating 4 unit cost values based on a handful of (up to 11) fields. Any time I want 1 of these 4 unit cost values, I'll want all 4. Which is quicker? Computing in the SQL Query ((a+b+c+d+e+f+g+h+i)/(j+k)), calling ComputeScalarUnitCost(datapoint.ID) 4 times, or joining to ComputeUnitCostTable(datapoint.ID) one time?

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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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  • Java Spotlight Episode 138: Paul Perrone on Life Saving Embedded Java

    - by Roger Brinkley
    Interview with Paul Perrone, founder and CEO of Perrone Robotics, on using Java Embedded to test autonomous vehicle operations for the Insurance Institute for Highway Safety that will save lives. Right-click or Control-click to download this MP3 file. You can also subscribe to the Java Spotlight Podcast Feed to get the latest podcast automatically. If you use iTunes you can open iTunes and subscribe with this link: Java Spotlight Podcast in iTunes. Show Notes News JDK 8 is Feature Complete Java SE 7 Update 25 Released What should the JCP be doing? 2013 Duke's Choice Award Nominations Another Quick update to Code Signing Article on OTN Events June 24, Austin JUG, Austin, TX June 25, Virtual Developer Day - Java, EMEA, 10AM CEST Jul 16-19, Uberconf, Denver, USA Jul 22-24, JavaOne Shanghai, China Jul 29-31, JVM Summit Language, Santa Clara Sep 11-12, JavaZone, Oslo, Norway Sep 19-20, Strange Loop, St. Louis Sep 22-26 JavaOne San Francisco 2013, USA Feature Interview Paul J. Perrone is founder/CEO of Perrone Robotics. Paul architected the Java-based general-purpose robotics and automation software platform known as “MAX”. Paul has overseen MAX’s application to rapidly field self-driving robotic cars, unmanned air vehicles, factory and road-side automation applications, and a wide range of advanced robots and automaton applications. He fielded a self-driving autonomous robotic dune buggy in the historic 2005 Grand Challenge race across the Mojave desert and a self-driving autonomous car in the 2007 Urban Challenge through a city landscape. His work has been featured in numerous televised and print media including the Discovery Channel, a theatrical documentary, scientific journals, trade magazines, and international press. Since 2008, Paul has also been working as the chief software engineer, CTO, and roboticist automating rock star Neil Young’s LincVolt, a 1959 Lincoln Continental retro-fitted as a fully autonomous extended range electric vehicle. Paul has been an engineer, author of books and articles on Java, frequent speaker on Java, and entrepreneur in the robotics and software space for over 20 years. He is a member of the Java Champions program, recipient of three Duke Awards including a Gold Duke and Lifetime Achievement Award, has showcased Java-based robots at five JavaOne keynotes, and is a frequent JavaOne speaker and show floor participant. He holds a B.S.E.E. from Rutgers University and an M.S.E.E. from the University of Virginia. What’s Cool Shenandoah: A pauseless GC for OpenJDK

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  • Introduction to Lean Software Development and Kanban Systems

    - by Ben Griswold
    Last year I took myself through a crash course on Lean Software Development and Kanban Systems in preparation for an in-house presentation.  I learned a bunch.  In this series, I’ll be sharing what I learned with you.   If your career looks anything like mine, you have probably been affiliated with a company or two which pushed requirements gathering and documentation to the nth degree. To add insult to injury, they probably added planning process (documentation, requirements, policies, meetings, committees) to the extent that it possibly retarded any progress. In my opinion, the typical company resembles the quote from Tom DeMarco. It isn’t enough just to do things right – we also had to say in advance exactly what we intended to do and then do exactly that. In the 1980s, Toyota turned the tables and revolutionize the automobile industry with their approach of “Lean Manufacturing.” A massive paradigm shift hit factories throughout the US and Europe. Mass production and scientific management techniques from the early 1900’s were questioned as Japanese manufacturing companies demonstrated that ‘Just-in-Time’ was a better paradigm. The widely adopted Japanese manufacturing concepts came to be known as ‘lean production’. Lean Thinking capitalizes on the intelligence of frontline workers, believing that they are the ones who should determine and continually improve the way they do their jobs. Lean puts main focus on people and communication – if people who produce the software are respected and they communicate efficiently, it is more likely that they will deliver good product and the final customer will be satisfied. In time, the abstractions behind lean production spread to logistics, and from there to the military, to construction, and to the service industry. As it turns out, principles of lean thinking are universal and have been applied successfully across many disciplines. Lean has been adopted by companies including Dell, FedEx, Lens Crafters, LLBean, SW Airlines, Digital River and eBay. Lean thinking got its name from a 1990’s best seller called The Machine That Changed the World : The Story of Lean Production. This book chronicles the movement of automobile manufacturing from craft production to mass production to lean production. Tom and Mary Poppendieck, that is.  Here’s one of their books: Implementing Lean Software Thinking: From Concept to Cash Our in-house presentations are supposed to run no more than 45 minutes.  I really cranked and got through my 87 slides in just under an hour. Of course, I had to cheat a little – I only covered the 7 principles and a single practice. In the next part of the series, we’ll dive into Principle #1: Eliminate Waste. And I am going to be a little obnoxious about listing my Lean and Kanban references with every series post.  The references are great and they deserve this sort of attention. 

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  • What does your Python development workbench look like?

    - by Fabian Fagerholm
    First, a scene-setter to this question: Several questions on this site have to do with selection and comparison of Python IDEs. (The top one currently is What IDE to use for Python). In the answers you can see that many Python programmers use simple text editors, many use sophisticated text editors, and many use a variety of what I would call "actual" integrated development environments – a single program in which all development is done: managing project files, interfacing with a version control system, writing code, refactoring code, making build configurations, writing and executing tests, "drawing" GUIs, and so on. Through its GUI, an IDE supports different kinds of workflows to accomplish different tasks during the journey of writing a program or making changes to an existing one. The exact features vary, but a good IDE has sensible workflows and automates things to let the programmer concentrate on the creative parts of writing software. The non-IDE way of writing large programs relies on a collection of tools that are typically single-purpose; they do "one thing well" as per the Unix philosophy. This "non-integrated development environment" can be thought of as a workbench, supported by the OS and generic interaction through a text or graphical shell. The programmer creates workflows in their mind (or in a wiki?), automates parts and builds a personal workbench, often gradually and as experience accumulates. The learning curve is often steeper than with an IDE, but those who have taken the time to do this can often claim deeper understanding of their tools. (Whether they are better programmers is not part of this question.) With advanced editor-platforms like Emacs, the pieces can be integrated into a whole, while with simpler editors like gedit or TextMate, the shell/terminal is typically the "command center" to drive the workbench. Sometimes people extend an existing IDE to suit their needs. What does your Python development workbench look like? What workflows have you developed and how do they work? For the first question, please give the main "driving" program – the one that you use to control the rest (Emacs, shell, etc.) the "small tools" -- the programs you reach for when doing different tasks For the second question, please describe what the goal of the workflow is (eg. "set up a new project" or "doing initial code design" or "adding a feature" or "executing tests") what steps are in the workflow and what commands you run for each step (eg. in the shell or in Emacs) Also, please describe the context of your work: do you write small one-off scripts, do you do web development (with what framework?), do you write data-munching applications (what kind of data and for what purpose), do you do scientific computing, desktop apps, or something else? Note: A good answer addresses the perspectives above – it doesn't just list a bunch of tools. It will typically be a long answer, not a short one, and will take some thinking to produce; maybe even observing yourself working.

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  • How to recover from finite-state-machine breakdown?

    - by Earl Grey
    My question may seems very scientific but I think it's a common problem and seasoned developers and programmers hopefully will have some advice to avoid the problem I mention in title. Btw., what I describe bellow is a real problem I am trying to proactively solve in my iOS project, I want to avoid it at all cost. By finite state machine I mean this I have a UI with a few buttons, several session states relevant to that UI and what this UI represents, I have some data which values are partly displayed in the UI, I receive and handle some external triggers (represented by callbacks from sensors). I made state diagrams to better map the relevant scenarios that are desirable and alowable in that UI and application. As I slowly implement the code, the app starts to behave more and more like it should. However, I am not very confident that it is robust enough. My doubts come from watching my own thinking and implementation process as it goes. I was confident that I had everything covered, but it was enough to make a few brute tests in the UI and I quickly realized that there are still gaps in the behavior ..I patched them. However, as each component depends and behaves based on input from some other component, a certain input from user or some external source trigers a chain of events, state changes..etc. I have several components and each behave like this Trigger received on input - trigger and its sender analyzed - output something (a message, a state change) based on analysis The problem is, this is not completely selfcontained, and my components (a database item, a session state, some button's state)...COULD be changed, influenced, deleted, or otherwise modified, outside the scope of the event-chain or desirable scenario. (phone crashes, battery is empty phone turn of suddenly) This will introduce a nonvalid situation into the system, from which the system potentially COULD NOT BE ABLE to recover. I see this (althought people do not realize this is the problem) in many of my competitors apps that are on apple store, customers write things like this "I added three documents, and after going there and there, i cannot open them, even if a see them." or "I recorded videos everyday, but after recording a too log video, I cannot turn of captions on them.., and the button for captions doesn't work".. These are just shortened examples, customers often describe it in more detail..from the descriptions and behavior described in them, I assume that the particular app has a FSM breakdown. So the ultimate question is how can I avoid this, and how to protect the system from blocking itself? EDIT I am talking in the context of one viewcontroller's view on the phone, I mean one part of the application. I Understand the MVC pattern, I have separate modules for distinct functionality..everything I describe is relevant to one canvas on the UI.

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  • Data Structures usage and motivational aspects

    - by Aubergine
    For long student life I was always wondering why there are so many of them yet there seems to be lack of usage at all in many of them. The opinion didn't really change when I got a job. We have brilliant books on what they are and their complexities, but I never encounter resources which would actually give a good hint of practical usage. I perfectly understand that I have to look at problem , analyse required operations, look for data structure that does them efficiently. However in practice I never do that, not because of human laziness syndrome, but because when it comes to work I acknowledge time priority over self-development. Over time I thought that when I would be better developer I will automatically use more of them - that didn't happen at all or maybe I just didn't. Then I found that the colleagues usually in the same plate as me - knowing more or less some three of data structures and being totally happy about it and refusing to discuss this matter further with me, coming back to conversations about 'cool new languages' 'libraries that do jobs for you' and the joy to work under scrumban etc. I am stuck with ArrayLists, Arrays and SortedMap , which no matter what I do always suffice or either I tweak them to be capable of fulfilling my task. Yes, it might be inefficient but do we really have to care if Intel increases performance over years no matter if we improve our skills? Does new Xeon or IBM machines really care what we use? What if I like build things, but I am not particularly excited whether it is n log(n) or just n? Over twenty years the processing power increased enormously, which gives us freedom of not being critical about which one to use? On top of that new more optimized languages appear which support multiple cores more efficiently. To be more specific: I would like to find motivational material on complex real areas/cases of possible effective usages of data structures. I would be really grateful if you would provide relevant resources. There is similar question ,but in the end the links again mostly describe or do dumb example(vehicles, students or holy grail quest - yes, very relevant) them and people keep referring to the "scenario decides the data structure to use". I want to know these complex scenarios to be able to identify similarities to my scenario and then use them. The complex scenarios where it really matters and not necessarily of quantitive nature. It seems that data structures only concern is efficiency and nothing else? There seems to be no particular convenience for developer in use one over another. (only when I found scientific resources on why exactly simple carbohydrates are evil I stopped eating sugar and candies completely replacing it with less harmful fruits - I hope you can see the analogy)

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  • Canonicalization issue regarding academic URL vs. blog URL

    - by user5395
    I'm sorry if what I am about to write is long-winded. I only wish to be clear. I am an academic in the scientific community. I maintain a web site for my research, teaching, and other professional activities. Until recently, the content for this site was hosted in a directory on my university department's own server. The address is of the typical form (universityname).edu/~(myusername) I decided that I wanted to use WordPress in order to host and manage my page. So I set up a WordPress.com blog and then replaced the index.html file in (universityname).edu/~(myusername) with a new one consisting of a single frame, containing the WordPress.com blog. Now when a user visits (universityname).edu/~(myusername), he or she sees the blog instead. This has been pretty nice because, even when the user clicks on links between pages or posts in the blog, the only thing showing up in the address bar of the browser is www.(universityname).edu/~(myusername), because the blog is constrained to a frame. However, the effect of this change on the search side of things has not been so kind to me. Before, when someone searched for my name in Google, the first result was always (universityname).edu/~(myusername). This is the most desirable outcome, for professional reasons. (Having my academic URL come up first suggests that I am an accredited professional, and not just some crank with a blog!) But now, Google seems to have canonicalized my web presence under the blog's WordPress.com address. It has completely forgotten about my academic URL and considers the WordPress.com address to be the best address representing me on the web. Unfortunately, WordPress.com doesn't support the canonical tag, so I can't tell the blog to advertise itself as my academic URL in the header. (It doesn't seem to help at all that I have used the WordPress.com dashboard to turn on no-indexing of the blog.) One obvious solution would be to use the departmental server to host my content again, and use a local installation of the WordPress platform. For reasons beyond my control, the platform will not be deployed on the departmental server at this time. Another solution would be to use shared hosting with WordPress.org support, because the WordPress.org platform does support the canonical tag (albeit via a plug-in). But this seems to usually require purchasing a domain name and other fees, and there is no guarantee that Google will listen to the canonical tag (it might use whatever domain name I end up with instead). Is there a way I can more cleverly integrate the WordPress.com blog into a page hosted on my department's server? Is there some PHP code I can write to retrieve the blog's contents in a way that Google won't treat as a link / "perceive" the blog? Please note: I am a PHP novice at best. I just feel there should be a simpler solution to all this, within the constraints of what I have described above. Thanks!

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  • Purple Cows, Copernicus, and Shampoo – Lessons in Customer Experience

    - by Christina McKeon
    What makes a great customer experience? And, why should you or your organization care? These are the questions that set the stage for the Oracle Customer Experience Summit, which kicked off yesterday in San Francisco. Day 1: The first day was filled with demos and insights from customer experience experts and Oracle customers sharing what it takes to deliver great customer experiences. Author Seth Godin delivered an entertaining presentation that included an in-depth exploration of the always-connected, always-sharing experience revolution that we are witnessing and yes, talked about the purple cow. It turns out that customer experience is your way to be the purple cow. Before everyone headed out to see Pearl Jam and Kings of Leon at the Oracle customer appreciation event, the day wrapped up with a discussion around building a customer-centric culture. Where do you start? Whom does it involve? What are some pitfalls to avoid? Day 2: The second day addressed the details behind all the questions brought up at the end of Day 1. Before you start on a customer experience initiative, Paul Hagen noted that you must understand you will forge a path similar to Copernicus. You will be proposing ideas and approaches that challenge current thinking in your organization. Just as Copernicus' heliocentric theory started a scientific revolution, your customer-centric efforts will start an experience revolution. If you think customer experience is like a traditional marketing approach, think again. It’s not about controlling your customers and leading them where you want them to go. It might sound like heresy to some, but your customers are already in control, whether or not your company realizes and acknowledges it. And, to survive and thrive, you'll have to focus on customers by thinking outside-in and working towards a brand that is better and more authentic. We learned how Vail Resorts takes this customer-centric approach. Employees must experience the mountain themselves and understand the experience from the guest’s standpoint. This has created a culture where employees do things for guests that are not expected. We also learned a valuable lesson in designing and innovating customer-centered experiences from Kerry Bodine. First you make the thing, and then you make the thing right. In this case, the thing is customer experience. Getting customer experience right means iterative prototyping and testing of your ideas. This is where shampoo comes in—think lather, rinse, repeat. Be prepared to keep repeating until the customer experience is right. Many of these sessions will be posted to YouTube in the coming weeks so be sure to subscribe to our CX channel.

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  • What is the difference between development and R&D?

    - by MainMa
    I was asked by a colleague to explain clearly the difference between ordinary development and research and development (R&D) and was unable to do it. After reading Wikipedia, I still don't have the precise answer. According to Wikipedia (slightly modified): There are two primary models: In one model, the primary function is to develop new products; in the other model, the primary function is to discover and create new knowledge about scientific and technological topics for the purpose of uncovering and enabling development of valuable new products, processes, and services. The first model is confusing. Does it mean that development (not R&D) consists exclusively in adding new features to a product, solving bugs and doing maintenance? What if something which was previously developed as a new feature becomes a separate product? The second model is less confusing, but still, how to qualify whether something is new knowledge or existent knowledge which is just rediscovered? Later, Wikipedia adds that ordinary development is different from R&D because of its: nearly immediate profit or immediate improvement. It's still not clear enough. How to qualify "nearly immediate profit"? What if a task has an immediate profit but requires heavy research? Or if it is basic but has uncertain profit, like the enforcement of a common style over the codebase? For example, does it belong to development or R&D to: Develop an engine which abstracts the access to the database, simplifying and shortening enormously the code of other applications (existent or ones which will be written in future) which should access to the database? Establish a new service-oriented architecture for the entire organization of company resources, in order to move from a bunch of separate and autonomous applications to a set of well-organized, interconnected web services, like what is used by Amazon? Design a new communication protocol to allow faster replication of data between two data centers of the company? Conceive a new type of software testing while working on a specific product, knowing that this type of testing will improve/simplify the testing process? Prove that Functional programming is more appropriate than OOP for a specific application, based on evidence, logic and previous experience? Enhance the existent application by adding gestures on tactile screens, after doing studies and testing that shows that those gestures improve the productivity of the users by a ratio of at least 1.4 for a precise set of tasks? Find a way to strongly enhance the Power usage effectiveness (PUE) of a data center? Create a Domain-Specific Language (DSL)? In short, how could I determine whether I'm doing R&D while working on something?

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  • What Precalculus knowledge is required before learning Discrete Math Computer Science topics?

    - by Ein Doofus
    Below I've listed the chapters from a Precalculus book as well as the author recommended Computer Science chapters from a Discrete Mathematics book. Although these chapters are from two specific books on these subjects I believe the topics are generally the same between any Precalc or Discrete Math book. What Precalculus topics should one know before starting these Discrete Math Computer Science topics?: Discrete Mathematics CS Chapters 1.1 Propositional Logic 1.2 Propositional Equivalences 1.3 Predicates and Quantifiers 1.4 Nested Quantifiers 1.5 Rules of Inference 1.6 Introduction to Proofs 1.7 Proof Methods and Strategy 2.1 Sets 2.2 Set Operations 2.3 Functions 2.4 Sequences and Summations 3.1 Algorithms 3.2 The Growths of Functions 3.3 Complexity of Algorithms 3.4 The Integers and Division 3.5 Primes and Greatest Common Divisors 3.6 Integers and Algorithms 3.8 Matrices 4.1 Mathematical Induction 4.2 Strong Induction and Well-Ordering 4.3 Recursive Definitions and Structural Induction 4.4 Recursive Algorithms 4.5 Program Correctness 5.1 The Basics of Counting 5.2 The Pigeonhole Principle 5.3 Permutations and Combinations 5.6 Generating Permutations and Combinations 6.1 An Introduction to Discrete Probability 6.4 Expected Value and Variance 7.1 Recurrence Relations 7.3 Divide-and-Conquer Algorithms and Recurrence Relations 7.5 Inclusion-Exclusion 8.1 Relations and Their Properties 8.2 n-ary Relations and Their Applications 8.3 Representing Relations 8.5 Equivalence Relations 9.1 Graphs and Graph Models 9.2 Graph Terminology and Special Types of Graphs 9.3 Representing Graphs and Graph Isomorphism 9.4 Connectivity 9.5 Euler and Hamilton Ptahs 10.1 Introduction to Trees 10.2 Application of Trees 10.3 Tree Traversal 11.1 Boolean Functions 11.2 Representing Boolean Functions 11.3 Logic Gates 11.4 Minimization of Circuits 12.1 Language and Grammars 12.2 Finite-State Machines with Output 12.3 Finite-State Machines with No Output 12.4 Language Recognition 12.5 Turing Machines Precalculus Chapters R.1 The Real-Number System R.2 Integer Exponents, Scientific Notation, and Order of Operations R.3 Addition, Subtraction, and Multiplication of Polynomials R.4 Factoring R.5 Rational Expressions R.6 Radical Notation and Rational Exponents R.7 The Basics of Equation Solving 1.1 Functions, Graphs, Graphers 1.2 Linear Functions, Slope, and Applications 1.3 Modeling: Data Analysis, Curve Fitting, and Linear Regression 1.4 More on Functions 1.5 Symmetry and Transformations 1.6 Variation and Applications 1.7 Distance, Midpoints, and Circles 2.1 Zeros of Linear Functions and Models 2.2 The Complex Numbers 2.3 Zeros of Quadratic Functions and Models 2.4 Analyzing Graphs of Quadratic Functions 2.5 Modeling: Data Analysis, Curve Fitting, and Quadratic Regression 2.6 Zeros and More Equation Solving 2.7 Solving Inequalities 3.1 Polynomial Functions and Modeling 3.2 Polynomial Division; The Remainder and Factor Theorems 3.3 Theorems about Zeros of Polynomial Functions 3.4 Rational Functions 3.5 Polynomial and Rational Inequalities 4.1 Composite and Inverse Functions 4.2 Exponential Functions and Graphs 4.3 Logarithmic Functions and Graphs 4.4 Properties of Logarithmic Functions 4.5 Solving Exponential and Logarithmic Equations 4.6 Applications and Models: Growth and Decay 5.1 Systems of Equations in Two Variables 5.2 System of Equations in Three Variables 5.3 Matrices and Systems of Equations 5.4 Matrix Operations 5.5 Inverses of Matrices 5.6 System of Inequalities and Linear Programming 5.7 Partial Fractions 6.1 The Parabola 6.2 The Circle and Ellipse 6.3 The Hyperbola 6.4 Nonlinear Systems of Equations

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  • How employable am I as a programmer?

    - by dsimcha
    I'm currently a Ph.D. student in Biomedical Engineering with a concentration in computational biology and am starting to think about what I want to do after graduate school. I feel like I've accumulated a lot of programming skills while in grad school, but taken a very non-traditional path to learning all this stuff. I'm wondering whether I would have an easy time getting hired as a programmer and could fall back on that if I can't find a good job directly in my field, and if so whether I would qualify for a more prestigious position than "code monkey". Things I Have Going For Me Approximately 4 years of experience programming as part of my research. I believe I have a solid enough grasp of the fundamentals that I could pick up new languages and technologies pretty fast, and could demonstrate this in an interview. Good math and statistics skills. An extensive portfolio of open source work (and the knowledge that working on these projects implies): I wrote a statistics library in D, mostly from scratch. I wrote a parallelism library (parallel map, reduce, foreach, task parallelism, pipelining, etc.) that is currently in review for adoption by the D standard library. I wrote a 2D plotting library for D against the GTK Cairo backend. I currently use it for most of the figures I make for my research. I've contributed several major performance optimizations to the D garbage collector. (Most of these were low-hanging fruit, but it still shows my knowledge of low-level issues like memory management, pointers and bit twiddling.) I've contributed lots of miscellaneous bug fixes to the D standard library and could show the change logs to prove it. (This demonstrates my ability read other people's code.) Things I Have Going Against Me Most of my programming experience is in D and Python. I have very little to virtually no experience in the more established, "enterprise-y" languages like Java, C# and C++, though I have learned a decent amount about these languages from small, one-off projects and discussions about language design in the D community. In general I have absolutely no knowledge of "enterprise-y" technlogies. I've never used a framework before, possibly because most reusable code for scientific work and for D tends to call itself a "library" instead. I have virtually no formal computer science/software engineering training. Almost all of my knowledge comes from talking to programming geek friends, reading blogs, forums, StackOverflow, etc. I have zero professional experience with the official title of "developer", "software engineer", or something similar.

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  • PostgreSQL lots of writes

    - by strife911
    Hi, I am using postgreSQL for a scientific application (unsupervised clustering). The python program is multi-threaded so that each thread manages its own postmaster process (one per core). Hence, their is a lot of concurrency. Each thread-process loop infinitely though two SQL queries. The first is for reading, the second is for writing. The read operation considers 500 time the amount of rows the write operation considers. Here is the output of dstat: ----total-cpu-usage---- ------memory-usage----- -dsk/total- --paging-- --io/total- usr sys idl wai hiq siq| used buff cach free| read writ| in out | read writ 4 0 32 64 0 0|3599M 63M 57G 1893M|1524k 16M| 0 0 | 98 2046 1 0 35 64 0 0|3599M 63M 57G 1892M|1204k 17M| 0 0 | 68 2062 2 0 32 66 0 0|3599M 63M 57G 1890M|1132k 17M| 0 0 | 62 2033 2 1 32 65 0 0|3599M 63M 57G 1904M|1236k 18M| 0 0 | 80 1994 2 0 31 67 0 0|3599M 63M 57G 1903M|1312k 16M| 0 0 | 70 1900 2 0 37 60 0 0|3599M 63M 57G 1899M|1116k 15M| 0 0 | 71 1594 2 1 37 60 0 0|3599M 63M 57G 1898M| 448k 17M| 0 0 | 39 2001 2 0 25 72 0 0|3599M 63M 57G 1896M|1192k 17M| 0 0 | 78 1946 1 0 40 58 0 0|3599M 63M 57G 1895M| 432k 15M| 0 0 | 38 1937 I am pretty sure I could write more often than that for I have seen it write up to 110-140M on dstat. How can I optimize this process?

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  • 202 blog articles

    - by mprove
    All my blog articles under blogs.oracle.com since August 2005: 202 blog articles Apr 2012 blogs.oracle.com design patch Mar 2012 Interaction 12 - Critique Mar 2012 Typing. Clicking. Dancing. Feb 2012 Desktop Mobility in Hospitals with Oracle VDI /video Feb 2012 Interaction 12 in Dublin - Highlights of Day 3 Feb 2012 Interaction 12 in Dublin - Highlights of Day 2 Feb 2012 Interaction 12 in Dublin - Highlights of Day 1 Feb 2012 Shit Interaction Designers Say Feb 2012 Tips'n'Tricks for WebCenter #3: How to display custom page titles in Spaces Jan 2012 Tips'n'Tricks for WebCenter #2: How to create an Admin menu in Spaces and save a lot of time Jan 2012 Tips'n'Tricks for WebCenter #1: How to apply custom resources in Spaces Jan 2012 Merry XMas and a Happy 2012! Dec 2011 One Year Oracle SocialChat - The Movie Nov 2011 Frank Ludolph's Last Working Day Nov 2011 Hans Rosling at TED Oct 2011 200 Countries x 200 Years Oct 2011 Blog Aggregation for Desktop Virtualization Oct 2011 Oracle VDI at OOW 2011 Sep 2011 Design for Conversations & Conversations for Design Sep 2011 All Oracle UX Blogs Aug 2011 Farewell Loriot Aug 2011 Oracle VDI 3.3 Overview Aug 2011 Sutherland's Closing Remarks at HyperKult Aug 2011 Surface and Subface Aug 2011 Back to Childhood in UI Design Jul 2011 The Art of Engineering and The Engineering of Art Jul 2011 Oracle VDI Seminar - June-30 Jun 2011 SGD White Paper May 2011 TEDxHamburg Live Feed May 2011 Oracle VDI in 3 Minutes May 2011 Space Ship Earth 2011 May 2011 blog moving times Apr 2011 Frozen tag cloud Apr 2011 Oracle: Hardware Software Complete in 1953 Apr 2011 Interaction Design with Wireframes Apr 2011 A guide to closing down a project Feb 2011 Oracle VDI 3.2.2 Jan 2011 free VDI charts Jan 2011 Sun Founders Panel 2006 Dec 2010 Sutherland on Leadership Dec 2010 SocialChat: Efficiency of E20 Dec 2010 ALWAYS ON Desktop Virtualization Nov 2010 12,000 Desktops at JavaOne Nov 2010 SocialChat on Sharing Best Practices Oct 2010 Globe of Visitors Oct 2010 SocialChat about the Next Big Thing Oct 2010 Oracle VDI UX Story - Wireframes Oct 2010 What's a PC anyway? Oct 2010 SocialChat on Getting Things Done Oct 2010 SocialChat on Infoglut Oct 2010 IT Twenty Twenty Oct 2010 Desktop Virtualization Webcasts from OOW Oct 2010 Oracle VDI 3.2 Overview Sep 2010 Blog Usability Top 7 Sep 2010 100 and counting Aug 2010 Oracle'izing the VDI Blogs Aug 2010 SocialChat on Apple Aug 2010 SocialChat on Video Conferencing Aug 2010 Oracle VDI 3.2 - Features and Screenshots Aug 2010 SocialChat: Don't stop making waves Aug 2010 SocialChat: Giving Back to the Community Aug 2010 SocialChat on Learning in Meetings Aug 2010 iPAD's Natural User Interface Jul 2010 Last day for Sun Microsystems GmbH Jun 2010 SirValUse Celebration Snippets Jun 2010 10 years SirValUse - Happy Birthday! Jun 2010 Wim on Virtualization May 2010 New Home for Oracle VDI Apr 2010 Renaissance Slide Sorter Comments Apr 2010 Unboxing Sun Ray 3 Plus Apr 2010 Desktop Virtualisierung mit Sun VDI 3.1 Apr 2010 Blog Relaunch Mar 2010 Social Messaging Slides from CeBIT Mar 2010 Social Messaging Talk at CeBIT Feb 2010 Welcome Oracle Jan 2010 My last presentation at Sun Jan 2010 Ivan Sutherland on Leadership Jan 2010 Learning French with Sun VDI Jan 2010 Learning Danish with Sun Ray Jan 2010 VDI workshop in Nieuwegein Jan 2010 Happy New Year 2010 Jan 2010 On Creating Slides Dec 2009 Best VDI Ever Nov 2009 How to store the Big Bang Nov 2009 Social Enterprise Tools. Beipiel Sun. Nov 2009 Nov-19 Nov 2009 PDF and ODF links on your blog Nov 2009 Q&A on VDI and MySQL Cluster Nov 2009 Zürich next week: Swiss Intranet Summit 09 Nov 2009 Designing for a Sustainable World - World Usabiltiy Day, Nov-12 Nov 2009 How to export a desktop from VDI 3 Nov 2009 Virtualisation Roadshow in the UK Nov 2009 Project Wonderland at EDUCAUSE 09 Nov 2009 VDI Roadshow in Dublin, Nov-26, 2009 Nov 2009 Sun VDI at EDUCAUSE 09 Nov 2009 Sun VDI 3.1 Architecture and New Features Oct 2009 VDI 3.1 is Early-Access Sep 2009 Virtualization for MySQL on VMware Sep 2009 Silpion & 13. Stock Sommerparty Sep 2009 Sun Ray and VMware View 3.1.1 2009-08-31 New Set of Sun Ray Status Icons 2009-08-25 Virtualizing the VDI Core? 2009-08-23 World Usability Day Hamburg 2009 - CfP 2009-07-16 Rising Sun 2009-07-15 featuring twittermeme 2009-06-19 ISC09 Student Party on June-20 /Hamburg 2009-06-18 Before and behind the curtain of JavaOne 2009-06-09 20k desktops at JavaOne 2009-06-01 sweet microblogging 2009-05-25 VDI 3 - Why you need 3 VDI hosts and what you can do about that? 2009-05-21 IA Konferenz 2009 2009-05-20 Sun VDI 3 UX Story - Power of the Web 2009-05-06 Planet of Sun and Oracle User Experience Design 2009-04-22 Sun VDI 3 UX Story - User Research 2009-04-08 Sun VDI 3 UX Story - Concept Workshops 2009-04-06 Localized documentation for Sun Ray Connector for VMware View Manager 1.1 2009-04-03 Sun VDI 3 Press Release 2009-03-25 Sun VDI 3 launches today! 2009-03-25 Sun Ray Connector for VMware View Manager 1.1 Update 2009-03-11 desktop virtualization wiki relaunch 2009-03-06 VDI 3 at CeBIT hall 6, booth E36 2009-03-02 Keyboard layout problems with Sun Ray Connector for VMware VDM 2009-02-23 wikis.sun.com tips & tricks 2009-02-23 Sun VDI 3 is in Early Access 2009-02-09 VirtualCenter unable to decrypt passwords 2009-02-02 Sun & VMware Desktop Training 2009-01-30 VDI at next09? 2009-01-16 Sun VDI: How to use virtual machines with multiple network adapters 2009-01-07 Sun Ray and VMware View 2009-01-07 Hamburg World Usability Day 2008 - Webcasts 2009-01-06 Sun Ray Connector for VMware VDM slides 2008-12-15 mother of all demos 2008-12-08 Build your own Thumper 2008-12-03 Troubleshooting Sun Ray Connector for VMware VDM 2008-12-02 My Roller Tag Cloud 2008-11-28 Sun Ray Connector: SSL connection to VDM 2008-11-25 Setting up SSL and Sun Ray Connector for VMware VDM 2008-11-13 Inspiration for Today and Tomorrow 2008-10-23 Sun Ray Connector for VMware VDM released 2008-10-14 From Sketchpad to ILoveSketch 2008-10-09 Desktop Virtualization on Xing 2008-10-06 User Experience Forum on Xing 2008-10-06 Sun Ray Connector for VMware VDM certified 2008-09-17 Virtual Clouds over Las Vegas 2008-09-14 Bill Verplank sketches metaphors 2008-09-04 End of Early Access - Sun Ray Connector for VMware 2008-08-27 Early Access: Sun Ray Connector for VMware Virtual Desktop Manager 2008-08-12 Sun Virtual Desktop Connector - Insides on Recycling Part 2 2008-07-20 Sun Virtual Desktop Connector - Insides on Recycling Part 3 2008-07-20 Sun Virtual Desktop Connector - Insides on Recycling 2008-07-20 lost in wiki space 2008-07-07 Evolution of the Desktop 2008-06-17 Virtual Desktop Webcast 2008-06-16 Woodstock 2008-06-16 What's a Desktop PC anyway? 2008-06-09 Virtual-T-Box 2008-06-05 Virtualization Glossary 2008-05-06 Five User Experience Principles 2008-04-25 Virtualization News Feed 2008-04-21 Acetylcholinesterase - Second Season 2008-04-18 Acetylcholinesterase - End of Signal 2007-12-31 Produkt-Management ist... 2007-10-22 Usability Verbände, Verteiler und Netzwerke. 2007-10-02 The Meaning is the Message 2007-09-28 Visualization Methods 2007-09-10 Inhouse und Open Source Projekte – Usability verankern und Synergien nutzen 2007-09-03 Der Schwabe Darth Vader entdeckt das Virale Marketing 2007-08-29 Dick Hardt 3.0 on Identity 2.0 2007-08-27 quality of written text depends on the tool 2007-07-27 podcasts for reboot9 2007-06-04 It is the user's itch that need to be scratched 2007-05-25 A duel at reboot9 2007-05-14 Taxonomien und Folksonomien - Tagging als neues HCI-Element 2007-05-10 Dueling Interaction Models of Personal-Computing and Web-Computing 2007-03-01 22.März: Weizenbaum. Rebel at Work. /Filmpremiere Hamburg 2007-02-25 Bruce Sterling at UbiComp 2006 /webcast 2006-11-12 FSOSS 2006 /webcasts 2006-11-10 Highway 101 2006-11-09 User Experience Roundtable Hamburg: EuroGEL 2006 2006-11-08 Douglas Adams' Hyperland (BBC 1990) 2006-10-08 Taxonomien und Folksonomien – Tagging als neues HCI-Element 2006-09-13 Usability im Unternehmen 2006-09-13 Doug does HyperScope 2006-08-26 TED Talks and TechTalks 2006-08-21 Kai Krause über seine Freundschaft zu Douglas Adams 2006-07-20 Rebel At Work: Film Portrait on Weizenbaum 2006-07-04 Gabriele Fischer, mp3 2006-06-07 Dick Hardt at ETech 06 2006-06-05 Weinberger: From Control to Conversation 2006-04-16 Eye Tracking at User Experience Roundtable Hamburg 2006-04-14 dropping knowledge 2006-04-09 GEL 2005 2006-03-13 slide photos of reboot7 2006-03-04 Dick Hardt on Identity 2.0 2006-02-28 User Experience Newsletter #13: Versioning 2006-02-03 Ester Dyson on Choice and Happyness 2006-02-02 Requirements-Engineering im Spannungsfeld von Individual- und Produktsoftware 2006-01-15 User Experience Newsletter #12: Intuition Quiz 2005-11-30 User Experience und Requirements-Engineering für Software-Projekte 2005-10-31 Ivan Sutherland on "Research and Fun" 2005-10-18 Ars Electronica / Mensch und Computer 2005 2005-09-14 60 Jahre nach Memex: Über die Unvereinbarkeit von Desktop- und Web-Paradigma 2005-08-31 reboot 7 2005-06-30

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  • Snort/Barnyard2 Logging

    - by Eric
    I need some help with my Snort/Barnyard2 setup. My goal is to have Snort send unified2 logs to Barnyard2 and then have Barnyard2 send the data to other locations. Here is my currrent setup. OS Scientific Linux 6 Snort Version 2.9.2.3 Barnyard2 Version 2.1.9 Snort command snort -c /etc/snort/snort.conf -i eth2 & Barnyard2 command /usr/local/bin/barnyard2 -c /etc/snort/barnyard2.conf -d /var/log/snort -f snort.log -w /var/log/snort/barnyard.waldo & snort.conf output unified2: filename snort.log, limit 128 barnyard2.conf output alert_syslog: host=127.0.0.1 output database: log, mysql, user=snort dbname=snort password=password host=localhost With this setup, barnyard2 is showing all of the correct information in the database and I'm using BASE to view it on the web GUI. I was hoping to be able to send the full packet data to syslog with barnyard2 but after reading around, it seems that it is impossible to do that. So I then started trying to modify the snort.conf file and add lines like "output alert_full: alert.full". This definitely gave me a lot more information but still not the full packet data like I want. So my question is, is there anyway I can use barnyard2 to send the full packet data of alerts to a human readable file? Since I can't send it directly to syslog, I can create another process to take the data from that file and ship it off to another server. If not, what flags and/or snort.conf configuration would you recommend to get the most data possible but still be able to handle quite a bit of traffic? In the end of it all, these alerts will be shipped to a central server via a SSH tunnel. I'm trying to stay away from databases.

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  • How can I bridge a VM to a remote network?

    - by asciiphil
    I have a system running QEMU/KVM (via libvirt). One of its VMs needs to have a presence on a subnet that is not local to the VM host. I have a Linux system on the remote subnet. Is there a way to set up some sort of tunneled bridge to cause the VM to appear present on the remote system? This will be a temporary situation (hopefully just until the VM owner can configure their system) and network performance and long-term maintainability aren't really issues. To give some more concrete information: My VM host has IP address 192.168.54.155/24. The VM has IP address 192.168.65.71/24. I have a remote system at 192.168.65.254/24. Both the VM host and remote system are running Scientific Linux 6.5. I do not control the network or routing in between the VM host and remote system. I do not have access to the guest OS on the VM. I would like traffic to the VM's IP address to end up at the VM even though its host isn't directly connected to the appropriate network. I've tried using iproute2's tunnelling, but Linux won't let me add a tunnel to a bridge. I've considered using some sort of iptables mangling to route traffic over the tunnel and make the VM think it's on the right network, but I'm not sure whether there are better approaches. What's the best way to accomplish this hack?

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  • Using 1920x1200 mode on SyncMaster T260HD in Linux

    - by dagorym
    I just got a Samsung SyncMaster T260HD monitor. It works straight out of the box with Windows but I can't seem to get it to work with Linux, which is my primary OS for day to day work. The computer boots up but when going into graphical mode on Linux the monitor gives me a "Mode not supported" error and doesn't display anything. I booted up windows and, using PowerStrip, grabbed the exact ModeLine that should be used to get the equivalent setting in Linux and added it to my xorg config file but it doesn't seem to help. the ModeLine is: ModeLine "1920x1200" 153.9 1920 1984 2016 2080 1200 1203 1209 1235 +hsync -vsync This is the modeline for the working display settings in windows but it doesn't seem to work in Linux My complete entry in the xorg.conf file for the monitor is Section "Monitor" Identifier "Monitor0" ModelName "SyncMaster" DisplaySize 518 324 HorizSync 30.0 - 81.0 VertRefresh 56.0 - 75.0 Option "dpms" ModeLine "1920x1200" 153.9 1920 1984 2016 2080 1200 1203 1209 1235 +hsync -vsync EndSection I'm running Scientific Linux 5.4 (clone of Redhat Enterprise Linux 5.4) but I've tried booting with a recent Linux Mint Distro as well as Ubuntu 9.04 and had the same problem. Any suggestions on other things I should try or might be missing? If anyone's gotten this to work I'd love to know. Thanks.

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  • Is there a fix to display 0 when arithmetic underflow occurs on the Windows 7 calculator?

    - by Pascal Qyy
    I have a problem that exasperates me: When I take the Windows 7 calculator in standard mode, if I do 4, then v (square root), the result is 2 Fine. But, at this point, if I do - (minus), then 2, the result is -1,068281969439142e-19 instead of 0! OK, I know about ? (machine epsilon), and yes, -1,068281969439142e-19 is less than the 64 bits ? (1.11e-16), so, we have an arithmetic underflow, in other words in this case: 0. Great, my computer is able to represent subnormal numbers instead of just flush to zero when this happens, and it seems that it is an improvement! Subnormal values fill the underflow gap with values where the absolute distance between them are the same as for adjacent values just outside of the underflow gap. This is an improvement over the older practice to just have zero in the underflow gap, and where underflowing results were replaced by zero (flush to zero). BUT: this result is false! when you try to explain the concept of the square root to a child and you end up with this kind of result, it only complicates your task... what is the point to represent subnormal numbers in a standard, non scientific calculator? So, is there a way to fix this?

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  • Filtered Router Interface

    - by jviotti
    I'm having some problems with a Scientific-Atlanta DPR2320R2. In specific with the WIFI. A few months ago I changed its password and username and now I can't remember. So I tried cracking it with Hydra but it drove things worse. Content of webadmin was rendered partial, and threw lot of errors. I then reseted the router. I found myself abled to browse the web with ethernet-connected pc. Wifi is configured by registering the device's MAC Address, and indeed the router has been reseted and register MAC address were lost. No device could connect to wifi. In fact, the device does not even recognize the network. I tried the pointing to 192.168.0.1 to restablish the MAC's. But I couldn't connect to the router access point. Tried listing up hosts: $ nmap -sP 192.168.0.0/24 Starting Nmap 5.00 ( http://nmap.org ) at 2012-12-11 01:18 ART Host 192.168.0.1 is up (0.0018s latency). Host 192.168.0.11 is up (0.00025s latency). Nmap done: 256 IP addresses (2 hosts up) scanned in 59.62 seconds Then checked 192.168.0.1 was really up by sending pings. It responded to all my pings. I quick-scanned the access point: $ nmap 192.168.0.1 Starting Nmap 5.00 ( http://nmap.org ) at 2012-12-11 01:08 ART Interesting ports on 192.168.0.1: Not shown: 999 closed ports PORT STATE SERVICE 80/tcp filtered http Nmap done: 1 IP address (1 host up) scanned in 6.73 seconds Look the state of the port 80: FILTERED. I'm pretty confused now. Any suggestion would be appreciated. Thanks in advance.

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  • Can Microsoft Build Appliances?

    - by andrewbrust
    Billy Hollis, my Visual Studio Live! colleague and fellow Microsoft Regional Director said recently, and I am paraphrasing, that the computing world, especially on the consumer side, has shifted from one of building hardware and software that makes things possible to do, to building products and technologies that make things easy to do.  Billy crystalized things perfectly, as he often does. In this new world of “easy to do,” Apple has done very well and Microsoft has struggled.  In the old world, customers wanted a Swiss Army Knife, with the most gimmicks and gadgets possible.  In the new world, people want elegantly cutlery.  They may want cake cutters and utility knives too, but they don’t want one device that works for all three tasks.  People don’t want tools, they want utensils.  People don’t want machines.  They want appliances. Microsoft Appliances: They Do Exist Microsoft has built a few appliance-like devices.  I would say XBox 360 is an appliance,  It’s versatile, mind you, but it’s the kind of thing you plug in, turn on and use, as opposed to set-up, tune, and open up to upgrade the internals.  Windows Phone 7 is an appliance too.  It’s a true smartphone, unlike Windows Mobile which was a handheld computer with a radio stack.  Zune is an appliance too, and a nice one.  It hasn’t attained much traction in the market, but that’s probably because the seminal consumer computing appliance -- the iPod – got there so much more quickly. In the embedded world, Mediaroom, Microsoft’s set-top product for the cable industry (used by AT&T U-Verse and others) is an appliance.  So is Microsoft’s Sync technology, used in Ford automobiles.  Even on the enterprise side, Microsoft has an appliance: SQL Server Parallel Data Warehouse Edition (PDW) combines Microsoft software with select OEMs’ server, networking and storage hardware.  You buy the appliance units from the OEMs, plug them in, connect them and go. I would even say that Bing is an appliance.  Not in the hardware sense, mind you.  But from the software perspective, it’s a single-purpose product that you visit or run, use and then move on.  You don’t have to install it (except the iOS and Android native apps where it’s pretty straightforward), you don’t have to customize it, you don’t have to program it.  Basically, you just use it. Microsoft Appliances that Should Exist But Microsoft builds a bunch of things that are not appliances.  Media Center is not an appliance, and it most certainly should be.  Instead, it’s an app that runs on Windows 7.  It runs full-screen and you can use this configuration to conceal the fact that Windows is under it, but eventually something will cause you to abandon that masquerade (like Patch Tuesday). The next version of Windows Home Server won’t, in my opinion, be an appliance either.  Now that the Drive Extender technology is gone, and users can’t just add and remove drives into and from a single storage pool, the product is much more like a IT server and less like an appliance-premised one.  Much has been written about this decision by Microsoft.  I’ll just sum it up in one word: pity. Microsoft doesn’t have anything remotely appliance-like in the tablet category, either.  Until it does, it likely won’t have much market share in that space either.  And of course, the bulk of Microsoft’s product catalog on the business side is geared to enterprise machines and not personal appliances. Appliance DNA: They Gotta Have It. The consumerization of IT is real, because businesspeople are consumers too.  They appreciate the fit and finish of appliances at home, and they increasingly feel entitled to have it at work too.  Secure and reliable push email in a smartphone is necessary, but it isn’t enough.  People want great apps and a pleasurable user experience too.  The full Microsoft Office product is needed at work, but a PC with a keyboard and mouse, or maybe a touch screen that uses a stylus (or requires really small fingers), to run Office isn’t enough either.  People want a flawless touch experience available for the times they want to read and take quick notes.  Until Microsoft realizes this fully and internalizes it, it will suffer defeats in the consumer market and even setbacks in the business market.  Think about how slow the Office upgrade cycle is…now imagine if the next version of Office had a first-class alternate touch UI and consider the possible acceleration in adoption rates. Can Microsoft make the appliance switch?  Can the appliance mentality become pervasive at the company?  Can Microsoft hasten its release cycles dramatically and shed the “some assembly required” paradigm upon which many of its products are based?  Let’s face it, the chances that Microsoft won’t make this transition are significant. But there are also encouraging signs, and they should not be ignored.  The appliances we have already discussed, especially Xbox, Zune and Windows Phone 7, are the most obvious in this regard.  The fact that SQL Server has an appliance SKU now is a more subtle but perhaps also more significant outcome, because that product sits so smack in the middle of Microsoft’s enterprise stack.  Bing is encouraging too, especially given its integrated travel, maps and augmented reality capabilities.  As Bing gains market share, Microsoft has tangible proof that it can transform and win, even when everyone outside the company, and many within it, would bet otherwise. That Great Big Appliance in the Sky Perhaps the most promising (and evolving) proof points toward the appliance mentality, though, are Microsoft’s cloud offerings -- Azure and BPOS/Office 365.  While the cloud does not represent a physical appliance (quite the opposite in fact) its ability to make acquisition, deployment and use of technology simple for the user is absolutely an embodiment of the appliance mentality and spirit.  Azure is primarily a platform as a service offering; it doesn’t just provide infrastructure.  SQL Azure does likewise for databases.  And Office 365 does likewise for SharePoint, Exchange and Lync. You don’t administer, tune and manage servers; instead, you create databases or site collections or mailboxes and start using them. Upgrades come automatically, and it seems like releases will come more frequently.  Fault tolerance and content distribution is just there.  No muss.  No fuss.  You use these services; you don’t have to set them up and think about them.  That’s how appliances work.  To me, these signs point out that Microsoft has the full capability of transforming itself.  But there’s a lot of work ahead.  Microsoft may say they’re “all in” on the cloud, but the majority of the company is still oriented around its old products and models.  There needs to be a wholesale cultural transformation in Redmond.  It can happen, but product management, program management, the field and executive ranks must unify in the effort. So must partners, and even customers.  New leaders must rise up and Microsoft must be able to see itself as a winner.  If Microsoft does this, it could lock-in decades of new success, and be a standard business school case study for doing so.  If not, the company will have missed an opportunity, and may see its undoing.

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  • PostgreSQL 8.4 - Tablespace Optimization

    - by FloE
    I'm currently running a PostgreSQL Database with about 1.5 billion rows / 500 GB of data (including indices). There are several schemata: on for the (read only, irregular changes / updates) 'core-model' and one for every user (about 20 persons). The users can access the core and store data in their own schema, so everything is located in one database. The server runs with CentOS and PostgreSQL 8.4 and is used for scientific studies, exploration etc and is running quite well. These days an upgrade of the DB storage hard disks arrive - all with the same performance as the old ones. I'm looking for the best way to distribute the data on these disks. It would be possible to separate frequently used objects (the core-data) from the user schemata, but I'm not sure if this is really worth the effort. It seems to be a much better idea to move the WAL files (pg_xlog directory) to its own partition. http://www.postgresql.org/docs/8.4/static/wal-internals.html What are your opinions? Are there any tablespace- or partitioning-related performance documentations / benchmarks?

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  • Getting rsync to move file from source to destination ?

    - by fabien-barbier
    Is rsync is a good choice for my project ? I have to : - copy files from source to destination folder via SSH, - be sure all files are copied, - delete source files after copy. - if I have conflict name, I have to rename files. It looks like I can use option : --remove-source-files (to delete source files) But how rsync manage conflict, can I had rules ? Use case on my project : I run scientific calculation on server A and results are inserted in folder "process", for each calculation I have a repository like this : /process/calc1. Now I would like to transfer repository "/calc1" to server B (I get /process/calc1), and delete "calc1" from server A. ...During another calculation I get "/process/calc2" on server A, the idea is also to move "calc2" in "/process/" directory on server B, then I have now on server B : - /process/calc1 - /process/calc2 (and /process/ on server A is empty). How rsync will manage conflict (on server B) if I have another folder like "/process/calc1" in server A after a new calculation (if "/process/calc1" already exist on server B) ? Is it possible to add rules with rsync, and rename "/process/calc1" by "process/calc1R2" in server B ? And so on (ex:calc1R3) ? Thanks.

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  • Building an OpenStack Cloud for Solaris Engineering, Part 1

    - by Dave Miner
    One of the signature features of the recently-released Solaris 11.2 is the OpenStack cloud computing platform.  Over on the Solaris OpenStack blog the development team is publishing lots of details about our version of OpenStack Havana as well as some tips on specific features, and I highly recommend reading those to get a feel for how we've leveraged Solaris's features to build a top-notch cloud platform.  In this and some subsequent posts I'm going to look at it from a different perspective, which is that of the enterprise administrator deploying an OpenStack cloud.  But this won't be just a theoretical perspective: I've spent the past several months putting together a deployment of OpenStack for use by the Solaris engineering organization, and now that it's in production we'll share how we built it and what we've learned so far.In the Solaris engineering organization we've long had dedicated lab systems dispersed among our various sites and a home-grown reservation tool for developers to reserve those systems; various teams also have private systems for specific testing purposes.  But as a developer, it can still be difficult to find systems you need, especially since most Solaris changes require testing on both SPARC and x86 systems before they can be integrated.  We've added virtual resources over the years as well in the form of LDOMs and zones (both traditional non-global zones and the new kernel zones).  Fundamentally, though, these were all still deployed in the same model: our overworked lab administrators set up pre-configured resources and we then reserve them.  Sounds like pretty much every traditional IT shop, right?  Which means that there's a lot of opportunity for efficiencies from greater use of virtualization and the self-service style of cloud computing.  As we were well into development of OpenStack on Solaris, I was recruited to figure out how we could deploy it to both provide more (and more efficient) development and test resources for the organization as well as a test environment for Solaris OpenStack.At this point, let's acknowledge one fact: deploying OpenStack is hard.  It's a very complex piece of software that makes use of sophisticated networking features and runs as a ton of service daemons with myriad configuration files.  The web UI, Horizon, doesn't often do a good job of providing detailed errors.  Even the command-line clients are not as transparent as you'd like, though at least you can turn on verbose and debug messaging and often get some clues as to what to look for, though it helps if you're good at reading JSON structure dumps.  I'd already learned all of this in doing a single-system Grizzly-on-Linux deployment for the development team to reference when they were getting started so I at least came to this job with some appreciation for what I was taking on.  The good news is that both we and the community have done a lot to make deployment much easier in the last year; probably the easiest approach is to download the OpenStack Unified Archive from OTN to get your hands on a single-system demonstration environment.  I highly recommend getting started with something like it to get some understanding of OpenStack before you embark on a more complex deployment.  For some situations, it may in fact be all you ever need.  If so, you don't need to read the rest of this series of posts!In the Solaris engineering case, we need a lot more horsepower than a single-system cloud can provide.  We need to support both SPARC and x86 VM's, and we have hundreds of developers so we want to be able to scale to support thousands of VM's, though we're going to build to that scale over time, not immediately.  We also want to be able to test both Solaris 11 updates and a release such as Solaris 12 that's under development so that we can work out any upgrade issues before release.  One thing we don't have is a requirement for extremely high availability, at least at this point.  We surely don't want a lot of down time, but we can tolerate scheduled outages and brief (as in an hour or so) unscheduled ones.  Thus I didn't need to spend effort on trying to get high availability everywhere.The diagram below shows our initial deployment design.  We're using six systems, most of which are x86 because we had more of those immediately available.  All of those systems reside on a management VLAN and are connected with a two-way link aggregation of 1 Gb links (we don't yet have 10 Gb switching infrastructure in place, but we'll get there).  A separate VLAN provides "public" (as in connected to the rest of Oracle's internal network) addresses, while we use VxLANs for the tenant networks. One system is more or less the control node, providing the MySQL database, RabbitMQ, Keystone, and the Nova API and scheduler as well as the Horizon console.  We're curious how this will perform and I anticipate eventually splitting at least the database off to another node to help simplify upgrades, but at our present scale this works.I had a couple of systems with lots of disk space, one of which was already configured as the Automated Installation server for the lab, so it's just providing the Glance image repository for OpenStack.  The other node with lots of disks provides Cinder block storage service; we also have a ZFS Storage Appliance that will help back-end Cinder in the near future, I just haven't had time to get it configured in yet.There's a separate system for Neutron, which is our Elastic Virtual Switch controller and handles the routing and NAT for the guests.  We don't have any need for firewalling in this deployment so we're not doing so.  We presently have only two tenants defined, one for the Solaris organization that's funding this cloud, and a separate tenant for other Oracle organizations that would like to try out OpenStack on Solaris.  Each tenant has one VxLAN defined initially, but we can of course add more.  Right now we have just a single /24 network for the floating IP's, once we get demand up to where we need more then we'll add them.Finally, we have started with just two compute nodes; one is an x86 system, the other is an LDOM on a SPARC T5-2.  We'll be adding more when demand reaches the level where we need them, but as we're still ramping up the user base it's less work to manage fewer nodes until then.My next post will delve into the details of building this OpenStack cloud's infrastructure, including how we're using various Solaris features such as Automated Installation, IPS packaging, SMF, and Puppet to deploy and manage the nodes.  After that we'll get into the specifics of configuring and running OpenStack itself.

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  • Solution to easily share large files with non-tech-savvy users?

    - by Tim
    Hey all, We've got a server setup at work which we'd like to use to exchange large files with known clients easily. We're looking into software to facilitate this, but somewhow typing "large file hosting" into Google gives questionable results.. ;) We've come up with the following requirements, and I hope any of you can points us in the direction of a solution that offers this functionality, or is malleable to our needs. Synchronization / revision management is of no concern, it's mostly single large (up to 1+ GB) file uploads & downloads we'll need. We'd like to make the downloads expire & be removed after a certain number of days / downloads, to limit the amount of cleanup we'd have to do. The data files exchanged sometimes hold confidential information, so the URLs generated should be random and not publicly visible. Our users are of the less technically savvy variety, so a simple webform would be best over a desktop client (because we also have to support a mix of operating systems). As for use of the system we'd either like to send out generated random URLs for them to upload their files, or have an easy way manage & expire users. Works on a linux (Ubuntu) server (so nothing .Net-related please) Does anyone know of software that fits the above criteria? We've already seen a few instances of this within the scientific community, but nothing we could use directly.. Best regards, Tim

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