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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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  • LINQ and ArcObjects

    - by Marko Apfel
    Motivation LINQ (language integrated query) is a component of the Microsoft. NET Framework since version 3.5. It allows a SQL-like query to various data sources such as SQL, XML etc. Like SQL also LINQ to SQL provides a declarative notation of problem solving – i.e. you don’t need describe in detail how a task could be solved, you describe what to be solved at all. This frees the developer from error-prone iterator constructs. Ideally, of course, would be to access features with this way. Then this construct is conceivable: var largeFeatures = from feature in features where (feature.GetValue("SHAPE_Area").ToDouble() > 3000) select feature; or its equivalent as a lambda expression: var largeFeatures = features.Where(feature => (feature.GetValue("SHAPE_Area").ToDouble() > 3000)); This requires an appropriate provider, which manages the corresponding iterator logic. This is easier than you might think at first sight - you have to deliver only the desired entities as IEnumerable<IFeature>. LINQ automatically establishes a state machine in the background, whose execution is delayed (deferred execution) - when you are really request entities (foreach, Count (), ToList (), ..) an instantiation processing takes place, although it was already created at a completely different place. Especially in multiple iteration through entities in the first debuggings you are rubbing your eyes when the execution pointer jumps magically back in the iterator logic. Realization A very concise logic for constructing IEnumerable<IFeature> can be achieved by running through a IFeatureCursor. You return each feature via yield. For an easier usage I have put the logic in an extension method Getfeatures() for IFeatureClass: public static IEnumerable<IFeature> GetFeatures(this IFeatureClass featureClass, IQueryFilter queryFilter, RecyclingPolicy policy) { IFeatureCursor featureCursor = featureClass.Search(queryFilter, RecyclingPolicy.Recycle == policy); IFeature feature; while (null != (feature = featureCursor.NextFeature())) { yield return feature; } //this is skipped in unit tests with cursor-mock if (Marshal.IsComObject(featureCursor)) { Marshal.ReleaseComObject(featureCursor); } } So you can now easily generate the IEnumerable<IFeature>: IEnumerable<IFeature> features = _featureClass.GetFeatures(RecyclingPolicy.DoNotRecycle); You have to be careful with the recycling cursor. After a delayed execution in the same context it is not a good idea to re-iterated on the features. In this case only the content of the last (recycled) features is provided and all the features are the same in the second set. Therefore, this expression would be critical: largeFeatures.ToList(). ForEach(feature => Debug.WriteLine(feature.OID)); because ToList() iterates once through the list and so the the cursor was once moved through the features. So the extension method ForEach() always delivers the same feature. In such situations, you must not use a recycling cursor. Repeated executions of ForEach() is not a problem, because for every time the state machine is re-instantiated and thus the cursor runs again - that's the magic already mentioned above. Perspective Now you can also go one step further and realize your own implementation for the interface IEnumerable<IFeature>. This requires that only the method and property to access the enumerator have to be programmed. In the enumerator himself in the Reset() method you organize the re-executing of the search. This could be archived with an appropriate delegate in the constructor: new FeatureEnumerator<IFeatureclass>(_featureClass, featureClass => featureClass.Search(_filter, isRecyclingCursor)); which is called in Reset(): public void Reset() { _featureCursor = _resetCursor(_t); } In this manner, enumerators for completely different scenarios could be implemented, which are used on the client side completely identical like described above. Thus cursors, selection sets, etc. merge into a single matter and the reusability of code is increasing immensely. On top of that in automated unit tests an IEnumerable could be mocked very easily - a major step towards better software quality. Conclusion Nevertheless, caution should be exercised with these constructs in performance-relevant queries. Because of managing a state machine in the background, a lot of overhead is created. The processing costs additional time - about 20 to 100 percent. In addition, working without a recycling cursor is fast a performance gap. However declarative LINQ code is much more elegant, flawless and easy to maintain than manually iterating, compare and establish a list of results. The code size is reduced according to experience an average of 75 to 90 percent! So I like to wait a few milliseconds longer. As so often it has to be balanced between maintainability and performance - which for me is gaining in priority maintainability. In times of multi-core processors, the processing time of most business processes is anyway not dominated by code execution but by waiting for user input. Demo source code The source code for this prototype with several unit tests, you can download here: https://github.com/esride-apf/Linq2ArcObjects. .

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  • NetBeans IDE 7.3 Knows Null

    - by Geertjan
    What's the difference between these two methods, "test1" and "test2"? public int test1(String str) {     return str.length(); } public int test2(String str) {     if (str == null) {         System.err.println("Passed null!.");         //forgotten return;     }     return str.length(); } The difference, or at least, the difference that is relevant for this blog entry, is that whoever wrote "test2" apparently thinks that the variable "str" may be null, though did not provide a null check. In NetBeans IDE 7.3, you see this hint for "test2", but no hint for "test1", since in that case we don't know anything about the developer's intention for the variable and providing a hint in that case would flood the source code with too many false positives:  Annotations are supported in understanding how a piece of code is intended to be used. If method return types use @Nullable, @NullAllowed, @CheckForNull, the value is considered to be "strongly possible to be null", as well as if the variable is tested to be null, as shown above. When using @NotNull, @NonNull, @Nonnull, the value is considered to be non-null. (The exact FQNs of the annotations are ignored, only simple names are checked.) Here are examples showing where the hints are displayed for the non-null hints (the "strongly possible to be null" hints are not shown below, though you can see one of them in the screenshot above), together with a comment showing what is shown when you hover over the hint: There isn't a "one size fits all" refactoring for these various instances relating to null checks, hence you can't do an automated refactoring across your code base via tools in NetBeans IDE, as shown yesterday for class member reordering across code bases. However, you can, instead, go to Source | Inspect and then do a scan throughout a scope (e.g., current file/package/project or combinations of these or all open projects) for class elements that the IDE identifies as potentially having a problem in this area: Thanks to Jan Lahoda, who reports that this currently also works in NetBeans IDE 7.3 dev builds for fields but that may need to be disabled since right now too many false positives are returned, for help with the info above and any misunderstandings are my own fault!

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  • Achieving decoupling in Model classes

    - by Guven
    I am trying to test-drive (or at least write unit tests) my Model classes but I noticed that my classes end up being too coupled. Since I can't break this coupling, writing unit tests is becoming harder and harder. To be more specific: Model Classes: These are the classes that hold the data in my application. They resemble pretty much the POJO (plain old Java objects), but they also have some methods. The application is not too big so I have around 15 model classes. Coupling: Just to give an example, think of a simple case of Order Header - Order Item. The header knows the item and the item knows the header (needs some information from the header for performing certain operations). Then, let's say there is the relationship between Order Item - Item Report. The item report needs the item as well. At this point, imagine writing tests for Item Report; you need have a Order Header to carry out the tests. This is a simple case with 3 classes; things get more complicated with more classes. I can come up with decoupled classes when I design algorithms, persistence layers, UI interactions, etc... but with model classes, I can't think of a way to separate them. They currently sit as one big chunk of classes that depend on each other. Here are some workarounds that I can think of: Data Generators: I have a package that generates sample data for my model classes. For example, the OrderHeaderGenerator class creates OrderHeaders with some basic data in it. I use the OrderHeaderGenerator from my ItemReport unit-tests so that I get an instance to OrderHeader class. The problem is these generators get complicated pretty fast and then I also need to test these generators; defeating the purpose a little bit. Interfaces instead of dependencies: I can come up with interfaces to get rid of the hard dependencies. For example, the OrderItem class would depend on the IOrderHeader interface. So, in my unit tests, I can easily mock the behaviour of an OrderHeader with a FakeOrderHeader class that implements the IOrderHeader interface. The problem with this approach is the complexity that the Model classes would end up having. Would you have other ideas on how to break this coupling in the model classes? Or, how to make it easier to unit-test the model classes?

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  • TechEd 2012: Windows 8 And Metro

    - by Tim Murphy
    Windows 8 is here (or at least very close) and that was the main feature of this morning’s key note.  Antoine LeBlond started off by apologizing to the IT professionals since he planned on showing code.  I’m not sure if IT Pros are that easily confused or why you would need such a disclaimer.  Developers do real work, IT Pros just play with toys (just kidding). The highlights of the Windows 8 keynote for me started with some of the UI design elements that I had not seen when I was shown one of the Build tablets.  Specifically I liked the AppBar features that we have become used to with Windows Phone and some of the gesture features.  Even though they have been available on other platforms before I think Microsoft really got them right. Two other great features of Windows 8 that they demonstrated were the Hyper-V capabilities and the ability to run Windows 8 anywhere from a USB key.  My jaw dropped through the floor seeing a feature rich OS boot off of a thumb drive. WOW!  I also can’t wait to get rid of dual booting just to run Hyper-V images when developing. The morning continued with a session on Metro XAML development with Tim Heuer.  While included a lot of great XAML Metro demos, I was pleasantly surprised by some of the things I found out about Visual Studio 2012.  Finding out that Blend is now integrated with VS2012 was a nice addition after working with them as separate applications was an encouraging start. Moving on to Metro he introduced the nugget that WinRT is Async everywhere.  How deep this model goes will be an interesting thing to find out as I learn more about developing for the platform.  Thankfully he followed that up with a couple of new keywords, await and async, that eliminates a lot of plumbing that has been required in the past for asynchronous transactions. Tim also related that since the Metro framework is relatively small and most apps will use a significant amount of it the entire surface is referenced by default.  This is a contrast to adding namespace and assemblies one after another as we normally do. This was such a power packed session that I can’t detail it all here so here is the teaser list. New icons in VS2012 for extension methods Emulator/simulator testing features for gestures Portable class libraries XAML no longer managed code And so much more …   del.icio.us Tags: Windows 8,Metro,Tim Heuer,XAML,Widows Phone,Hyper-V,Antoine LeBlond,TechEd,TechEd 2012,Visual Studio 2012,Visual Studio

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  • The Case of the Missing Date/Time Stamp: Reporting Services 2008 R2 Snapshots

    - by smisner
    This week I stumbled upon an undocumented “feature” in SQL Server 2008 R2 Reporting Services as I was preparing a demonstration on how to set up and use report snapshots. If you’re familiar with the main changes in this latest release of Reporting Services, you probably already know that Report Manager got a facelift this time around. Although this facelift was generally a good thing, one of the casualties – in my opinion – is the loss of the snapshot label that served two purposes… First, it flagged the report as a snapshot. Second, it let you know when that snapshot was created. As part of my standard operating procedure when demonstrating report snapshots, I point out this label, so I was rather taken aback when I didn’t see it in the demonstration I was preparing. It sort of upset my routine, and I’m rather partial to my routines. I thought perhaps I wasn’t looking in the right place and changed Report Manager from Tile View to Detail View, but no – that label was still missing. In the grand scheme of life, it’s not an earth-shattering change, but you’ll have to look at the Modified Date in Details View to know when the snapshot was run. Or hope that the report developer included a textbox to show the execution time in the report. (Hint: this is a good time to add this to your list of report development best practices, whether a report gets set up as a report snapshot or not!) A snapshot from the past In case you don’t remember how a snapshot appeared in Report Manager back in the old days (of SQL Server 2008 and earlier), here’s an image I snagged from my Reporting Services 2008 Step by Step manuscript: A snapshot in the present A report server running in SharePoint integrated mode had no such label. There you had to rely on the Report Modified date-time stamp to know the snapshot execution time. So I guess all platforms are now consistent. Here’s a screenshot of Report Manager in the 2008 R2 version. One of these is a snapshot and the rest execute on demand. Can you tell which is the snapshot? Consider descriptions as an alternative So my report snapshot demonstration has one less step, and I’ll need to edit the Denali version of the Step by Step book. Things are simpler this way, but I sure wish we had an easier way to identify the execution methods of the reports. Consider using the description field to alert users that the report is a snapshot. It might save you a few questions about why the data isn’t up-to-date if the users know that something changed in the source of the report. Notice that the full description doesn’t display in Tile View, so keep it short and sweet or instruct users to open Details View to see the entire description.

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  • SFX Played Once per Collision or Hit

    - by David Dimalanta
    I have a question about using Box2D (engine for LibGDX used to make realistic physics). I observed on the code that I've made for the physics here below: @Override public boolean touchUp(int screenX, int screenY, int pointer, int button) { // TODO Touch Up Event if(is_Next_Fruit_Touched) { BodyEditorLoader Fruit_Loader = new BodyEditorLoader(Gdx.files.internal("Shape_Physics/Fruity Physics.json")); Fruit_BD.type = BodyType.DynamicBody; Fruit_BD.position.set(x, y); FixtureDef Fruit_FD = new FixtureDef(); // --> Allows you to make the object's physics. Fruit_FD.density = 1.0f; Fruit_FD.friction = 0.7f; Fruit_FD.restitution = 0.2f; MassData mass = new MassData(); mass.mass = 5f; Fruit_Body[n] = world.createBody(Fruit_BD); Fruit_Body[n].setActive(true); // --> Let your dragon fall. Fruit_Body[n].setMassData(mass); Fruit_Body[n].setGravityScale(1.0f); System.out.println("Eggs... " + n); Fruit_Loader.attachFixture(Fruit_Body[n], Body, Fruit_FD, Fruit_IMG.getWidth()); Fruit_Origin = Fruit_Loader.getOrigin(Body, Fruit_IMG.getWidth()).cpy(); is_Next_Fruit_Touched = false; up = y; Gdx.app.log("Initial Y-coordinate", "Y at " + up); //Once it's touched, the next fruit will set to drag. if(n < 50) { n++; }else{ System.exit(0); } } return true; } Now, I'm thinking which part o line should I implement for the sound effects. My objectives to make SFX played once for every collision (Or should I say "SFX played once per collision"?) on the following: SFX played once if they hit on the objects of its kind. (e.g. apple vs. apple) SFX played once on a different sound when it hit on the ground. (e.g. apple land on the mud) Take note that I'm using Box2D for the Java programming version thanks to LibGDX via Box2D engine and I edited the physics body using Physics Body Editor before I implement it to code. I tried to check every available methods for body, fixture definition, or body definition to code for the SFX when hit but it seems only for the gravity and weight. Is there possibly available on the document for SFX played when collision happens if possible?

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  • How can I make a universal construction more efficient?

    - by VF1
    A "universal construction" is a wrapper class for a sequential object that enables it to be linearized (a strong consistency condition for concurrent objects). For instance, here's an adapted wait-free construction, in Java, from [1], which presumes the existence of a wait-free queue that satisfies the interface WFQ (which only requires one-time consensus between threads) and assumes a Sequential interface: public interface WFQ<T> // "FIFO" iteration { int enqueue(T t); // returns the sequence number of t Iterable<T> iterateUntil(int max); // iterates until sequence max } public interface Sequential { // Apply an invocation (method + arguments) // and get a response (return value + state) Response apply(Invocation i); } public interface Factory<T> { T generate(); } // generate new default object public interface Universal extends Sequential {} public class SlowUniversal implements Universal { Factory<? extends Sequential> generator; WFQ<Invocation> wfq = new WFQ<Invocation>(); Universal(Factory<? extends Sequential> g) { generator = g; } public Response apply(Invocation i) { int max = wfq.enqueue(i); Sequential s = generator.generate(); for(Invocation invoc : wfq.iterateUntil(max)) s.apply(invoc); return s.apply(i); } } This implementation isn't very satisfying, however, since it presumes determinism of a Sequential and is really slow. I attempted to add memory recycling: public interface WFQD<T> extends WFQ<T> { T dequeue(int n); } // dequeues only when n is the tail, else assists other threads public interface CopyableSequential extends Sequential { CopyableSequential copy(); } public class RecyclingUniversal implements Universal { WFQD<CopyableSequential> wfqd = new WFQD<CopyableSequential>(); Universal(CopyableSequential init) { wfqd.enqueue(init); } public Response apply(Invocation i) { int max = wfqd.enqueue(i); CopyableSequential cs = null; int ctr = max; for(CopyableSequential csq : wfq.iterateUntil(max)) if(--max == 0) cs = csq.copy(); wfqd.dequeue(max); return cs.apply(i); } } Here are my specific questions regarding the extension: Does my implementation create a linearizable multi-threaded version of a CopyableSequential? Is it possible extend memory recycling without extending the interface (perhaps my new methods trivialize the problem)? My implementation only reduces memory when a thread returns, so can this be strengthened? [1] provided an implementation for WFQ<T>, not WFQD<T> - one does exist, though, correct? [1] Herlihy and Shavit, The Art of Multiprocessor Programming.

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  • Design for an interface implementation that provides additional functionality

    - by Limbo Exile
    There is a design problem that I came upon while implementing an interface: Let's say there is a Device interface that promises to provide functionalities PerformA() and GetB(). This interface will be implemented for multiple models of a device. What happens if one model has an additional functionality CheckC() which doesn't have equivalents in other implementations? I came up with different solutions, none of which seems to comply with interface design guidelines: To add CheckC() method to the interface and leave one of its implementations empty: interface ISomeDevice { void PerformA(); int GetB(); bool CheckC(); } class DeviceModel1 : ISomeDevice { public void PerformA() { // do stuff } public int GetB() { return 1; } public bool CheckC() { bool res; // assign res a value based on some validation return res; } } class DeviceModel2 : ISomeDevice { public void PerformA() { // do stuff } public int GetB() { return 1; } public bool CheckC() { return true; // without checking anything } } This solution seems incorrect as a class implements an interface without truly implementing all the demanded methods. To leave out CheckC() method from the interface and to use explicit cast in order to call it: interface ISomeDevice { void PerformA(); int GetB(); } class DeviceModel1 : ISomeDevice { public void PerformA() { // do stuff } public int GetB() { return 1; } public bool CheckC() { bool res; // assign res a value based on some validation return res; } } class DeviceModel2 : ISomeDevice { public void PerformA() { // do stuff } public int GetB() { return 1; } } class DeviceManager { private ISomeDevice myDevice; public void ManageDevice(bool newDeviceModel) { myDevice = (newDeviceModel) ? new DeviceModel1() : new DeviceModel2(); myDevice.PerformA(); int b = myDevice.GetB(); if (newDeviceModel) { DeviceModel1 newDevice = myDevice as DeviceModel1; bool c = newDevice.CheckC(); } } } This solution seems to make the interface inconsistent. For the device that supports CheckC(): to add the logic of CheckC() into the logic of another method that is present in the interface. This solution is not always possible. So, what is the correct design to be used in such cases? Maybe creating an interface should be abandoned altogether in favor of another design?

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  • Oracle GoldenGate 11gR2 Event Marker System

    - by Doug Reid
    0 false 18 pt 18 pt 0 0 false false false /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} Oracle GoldenGate 11gR2 includes a number of refinements to the Event Marker system. Using event markers enables GoldenGate processes to take a defined action based on an event in the data stream. This feature within Oracle GoldenGate simplifies methods to embed specific custom processing in the areas of error handling, alerts, and notification. The event marker system effectively allows for DML driven workflows to be created within GoldenGate and enables customers to craft non-standard processing based on special events. There are a number of supported event actions including: trace, log, checkpoint before, suspend, abort, and several others. With 11gR1 events can now be triggered by DDL operations, plus variables can be passed in and out of the system to shell scripts. Some good use cases for this feature are Automatic switchover to the secondary system during planned outages Better monitoring over source systems’ performance and automated switchover to the standby system in case of an outage with the primary system Automatic switchover from initial load to changed data movement Automatic synchronization of any type of batch processing taking place on both the source and target databases for database consistency Automatic stoppage of the Delivery module to allow end-of-day reporting Finding, tracking, and reporting on transactions that are of interest including the ones that do not have primary keys or transaction record numbers If you would like to see a demo, please visit our youtube channel (http://youtube.com/oraclegoldengate)  To learn more about the new features of Oracle GoldenGate 11gR2 and to ask questions to the PM team, please join us on September 12th  8am or 10am PST for our live webcast. Click here to register.

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  • NHibernate Session Load vs Get when using Table per Hierarchy. Always use ISession.Get&lt;T&gt; for TPH to work.

    - by Rohit Gupta
    Originally posted on: http://geekswithblogs.net/rgupta/archive/2014/06/01/nhibernate-session-load-vs-get-when-using-table-per-hierarchy.aspxNHibernate ISession has two methods on it : Load and Get. Load allows the entity to be loaded lazily, meaning the actual call to the database is made only when properties on the entity being loaded is first accessed. Additionally, if the entity has already been loaded into NHibernate Cache, then the entity is loaded directly from the cache instead of querying the underlying database. ISession.Get<T> instead makes the call to the database, every time it is invoked. With this background, it is obvious that we would prefer ISession.Load<T> over ISession.Get<T> most of the times for performance reasons to avoid making the expensive call to the database. let us consider the impact of using ISession.Load<T> when we are using the Table per Hierarchy implementation of NHibernate. Thus we have base class/ table Animal, there is a derived class named Snake with the Discriminator column being Type which in this case is “Snake”. If we load This Snake entity using the Repository for Animal, we would have a entity loaded, as shown below: public T GetByKey(object key, bool lazy = false) { if (lazy) return CurrentSession.Load<T>(key); return CurrentSession.Get<T>(key); } var tRepo = new NHibernateReadWriteRepository<TPHAnimal>(); var animal = tRepo.GetByKey(new Guid("602DAB56-D1BD-4ECC-B4BB-1C14BF87F47B"), true); var snake = animal as Snake; snake is null As you can see that the animal entity retrieved from the database cannot be cast to Snake even though the entity is actually a snake. The reason being ISession.Load prevents the entity to be cast to Snake and will throw the following exception: System.InvalidCastException :  Message=Unable to cast object of type 'TPHAnimalProxy' to type 'NHibernateChecker.Model.Snake'. Thus we can see that if we lazy load the entity using ISession.Load<TPHAnimal> then we get a TPHAnimalProxy and not a snake. =============================================================== However if do not lazy load the same cast works perfectly fine, this is since we are loading the entity from database and the entity being loaded is not a proxy. Thus the following code does not throw any exceptions, infact the snake variable is not null: var tRepo = new NHibernateReadWriteRepository<TPHAnimal>(); var animal = tRepo.GetByKey(new Guid("602DAB56-D1BD-4ECC-B4BB-1C14BF87F47B"), false); var snake = animal as Snake; if (snake == null) { var snake22 = (Snake) animal; }

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  • Oracle At QCon SF 2012

    - by Cassandra Clark - OTN
    Oracle Technology Network is a Platinum sponsor at QCon San Francisco.  (qconsf.com).  Don’t miss these great developer focused sessions: Shay ShmeltzerHow we simplified Web, Mobile and Cloud development for our own developers? - the Oracle StoryOver the past several years, Oracle has beendeveloping a new set of enterprise applications in what is probably one of thelargest Java based development project in the world. How do you take 3000 developers and make them productive? How do you insure the delivery of cutting edge UIs for both Mobile and Web channels? How do you enable Cloud baseddevelopment and deployment?  Come and learn how we did it at Oracle, and see how the same technologies and methodologies can apply to your development efforts. Dan SmithProject Lambda in Java 8Java SE 8 will include major enhancements to the Java Programming Language and its core libraries.  This suite of new features, known as Project Lambda in the OpenJDK community, includes lambda expressions, default methods, and parallel collections (and much more!).  The result will be a next-generation Java programming experience with more flexibility and better abstractions.   This talk will introduce the new Java features and offer a behind-the-scenes view of how they evolved and why they work the way that they do. Arun GuptaJSR 356: Building HTML5 WebSocket Applications in JavaThe family of HTML5 technologies has pushed the pendulum away from rich client technologies and toward ever-more-capable Web clients running on today’s browsers. In particular, WebSocket brings new opportunities for efficient peer-to-peer communication, providing the basis for a new generation of interactive and “live” Web applications. This session examines the efforts under way to support WebSocket in the Java programming model, from its base-level integration in the Java Servlet and Java EE containers to a new, easy-to-use API and toolset that are destined to become part of the standard Java platform. The full conference schedule is here: http://qconsf.com/sf2012/schedule/wednesday.jsp But wait, there’s more!  At the Oracle booth, we’ll also be covering: ·         Oracle ADF Mobile·         Oracle Developer Cloud Service·         Oracle ADF Essentials·         NetBeans Project Easel Lastly we’ll share the results of a short cloud survey at QConSF ater this week.  If you attended this year's Oracle OpenWorld and JavaOne conferences, it would be hard not to notice that Oracle is clearly "all-in" when it comes to the Cloud.  With Cloud computing being such a hot topic on many OTN members' minds, we'd like to know what you're doing in the cloud and invite you to take this short cloud survey.

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  • Taking the Plunge - or Dipping Your Toe - into the Fluffy IAM Cloud by Paul Dhanjal (Simeio Solutions)

    - by Greg Jensen
    In our last three posts, we’ve examined the revolution that’s occurring today in identity and access management (IAM). We looked at the business drivers behind the growth of cloud-based IAM, the shortcomings of the old, last-century IAM models, and the new opportunities that federation, identity hubs and other new cloud capabilities can provide by changing the way you interact with everyone who does business with you. In this, our final post in the series, we’ll cover the key things you, the enterprise architect, should keep in mind when considering moving IAM to the cloud. Invariably, what starts the consideration process is a burning business need: a compliance requirement, security vulnerability or belt-tightening edict. Many on the business side view IAM as the “silver bullet” – and for good reason. You can almost always devise a solution using some aspect of IAM. The most critical question to ask first when using IAM to address the business need is, simply: is my solution complete? Typically, “business” is not focused on the big picture. Understandably, they’re focused instead on the need at hand: Can we be HIPAA compliant in 6 months? Can we tighten our new hire, employee transfer and termination processes? What can we do to prevent another password breach? Can we reduce our service center costs by the end of next quarter? The business may not be focused on the complete set of services offered by IAM but rather a single aspect or two. But it is the job – indeed the duty – of the enterprise architect to ensure that all aspects are being met. It’s like remodeling a house but failing to consider the impact on the foundation, the furnace or the zoning or setback requirements. While the homeowners may not be thinking of such things, the architect, of course, must. At Simeio Solutions, the way we ensure that all aspects are being taken into account – to expose any gaps or weaknesses – is to assess our client’s IAM capabilities against a five-step maturity model ranging from “ad hoc” to “optimized.” The model we use is similar to Capability Maturity Model Integration (CMMI) developed by the Software Engineering Institute (SEI) at Carnegie Mellon University. It’s based upon some simple criteria, which can provide a visual representation of how well our clients fair when evaluated against four core categories: ·         Program Governance ·         Access Management (e.g., Single Sign-On) ·         Identity and Access Governance (e.g., Identity Intelligence) ·         Enterprise Security (e.g., DLP and SIEM) Often our clients believe they have a solution with all the bases covered, but the model exposes the gaps or weaknesses. The gaps are ideal opportunities for the cloud to enter into the conversation. The complete process is straightforward: 1.    Look at the big picture, not just the immediate need – what is our roadmap and how does this solution fit? 2.    Determine where you stand with respect to the four core areas – what are the gaps? 3.    Decide how to cover the gaps – what role can the cloud play? Returning to our home remodeling analogy, at some point, if gaps or weaknesses are discovered when evaluating the complete impact of the proposed remodel – if the existing foundation wouldn’t support the new addition, for example – the owners need to decide if it’s time to move to a new house instead of trying to remodel the old one. However, with IAM it’s not an either-or proposition – i.e., either move to the cloud or fix the existing infrastructure. It’s possible to use new cloud technologies just to cover the gaps. Many of our clients start their migration to the cloud this way, dipping in their toe instead of taking the plunge all at once. Because our cloud services offering is based on the Oracle Identity and Access Management Suite, we can offer a tremendous amount of flexibility in this regard. The Oracle platform is not a collection of point solutions, but rather a complete, integrated, best-of-breed suite. Yet it’s not an all-or-nothing proposition. You can choose just the features and capabilities you need using a pay-as-you-go model, incrementally turning on and off services as needed. Better still, all the other capabilities are there, at the ready, whenever you need them. Spooling up these cloud-only services takes just a fraction of the time it would take a typical organization to deploy internally. SLAs in the cloud may be higher than on premise, too. And by using a suite of software that’s complete and integrated, you can dramatically lower cost and complexity. If your in-house solution cannot be migrated to the cloud, you might consider using hardware appliances such as Simeio’s Cloud Interceptor to extend your enterprise out into the network. You might also consider using Expert Managed Services. Cost is usually the key factor – not just development costs but also operational sustainment costs. Talent or resourcing issues often come into play when thinking about sustaining a program. Expert Managed Services such as those we offer at Simeio can address those concerns head on. In a cloud offering, identity and access services lend to the new paradigms described in my previous posts. Most importantly, it allows us all to focus on what we're meant to do – provide value, lower costs and increase security to our respective organizations. It’s that magic “silver bullet” that business knew you had all along. If you’d like to talk more, you can find us at simeiosolutions.com.

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  • Need help on a problemset in a programming contest

    - by topher
    I've attended a local programming contest on my country. The name of the contest is "ACM-ICPC Indonesia National Contest 2013". The contest has ended on 2013-10-13 15:00:00 (GMT +7) and I am still curious about one of the problems. You can find the original version of the problem here. Brief Problem Explanation: There are a set of "jobs" (tasks) that should be performed on several "servers" (computers). Each job should be executed strictly from start time Si to end time Ei Each server can only perform one task at a time. (The complicated thing goes here) It takes some time for a server to switch from one job to another. If a server finishes job Jx, then to start job Jy it will need an intermission time Tx,y after job Jx completes. This is the time required by the server to clean up job Jx and load job Jy. In other word, job Jy can be run after job Jx if and only if Ex + Tx,y = Sy. The problem is to compute the minimum number of servers needed to do all jobs. Example: For example, let there be 3 jobs S(1) = 3 and E(1) = 6 S(2) = 10 and E(2) = 15 S(3) = 16 and E(3) = 20 T(1,2) = 2, T(1,3) = 5 T(2,1) = 0, T(2,3) = 3 T(3,1) = 0, T(3,2) = 0 In this example, we need 2 servers: Server 1: J(1), J(2) Server 2: J(3) Sample Input: Short explanation: The first 3 is the number of test cases, following by number of jobs (the second 3 means that there are 3 jobs for case 1), then followed by Ei and Si, then the T matrix (sized equal with number of jobs). 3 3 3 6 10 15 16 20 0 2 5 0 0 3 0 0 0 4 8 10 4 7 12 15 1 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 8 10 4 7 12 15 1 4 0 50 50 50 50 0 50 50 50 50 0 50 50 50 50 0 Sample Output: Case #1: 2 Case #2: 1 Case #3: 4 Personal Comments: The time required can be represented as a graph matrix, so I'm supposing this as a directed acyclic graph problem. Methods I tried so far is brute force and greedy, but got Wrong Answer. (Unfortunately I don't have my code anymore) Could probably solved by dynamic programming too, but I'm not sure. I really have no clear idea on how to solve this problem. So a simple hint or insight will be very helpful to me.

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  • To make or not to make...python-nautilus a dependency?

    - by George Edison
    That is the question! Okay, all silliness aside, I really am forced to make a difficult decision here. My application is written in C++ and allows other scripts to invoke methods via XML-RPC. One of these scripts is a Nautilus extension written in Python. The extension is packaged with the rest of the application and copied to the appropriate place when installed (/usr/share/nautilus-python/extensions). Now the problem is that the Nautilus extension requires the python-nautilus package to be installed to be operational. So therefore I have three options: Make the python-nautilus package a dependency. This option will ensure that anyone who installs my package will be able to use the Nautilus extension. However, this option will not be attractive to XFCE or KDE users - a ton of python-nautilus's dependencies will be installed on their machines and take up a lot of space - even if they never use Nautilus. Put the python-nautilus package in the suggests: or recommends: field. This option provides the end-user with a way to avoid installing the python-nautilus package (by providing the --no-install-suggests or --no-install-recommends argument to apt-get). However, this won't work when the user installs the package in the Software Center. (I always get mixed up as to which of those two fields are installed by default.) Prompt the user when the application is installed or first launched. This option is more complicated than the others but offers the best compromise between making it easy for the user to install python-nautilus (without going into a technical explanation) and not installing it when the user doesn't need it (or want it). I guess the best way to implement this is a simple prompt that invokes apt-get if the user would like the package installed. Don't install the package at all. This option ensures that nobody has python-nautilus installed on their machine unless they want it. However, this also means that my Nautilus extension will simply not run on the end-user's machine unless they manually install the package. Which of these options seems the best choice? Have I missed any pros and cons for each of the options?

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  • Is code like this a "train wreck" (in violation of Law of Demeter)?

    - by Michael Kjörling
    Browsing through some code I've written, I came across the following construct which got me thinking. At a first glance, it seems clean enough. Yes, in the actual code the getLocation() method has a slightly more specific name which better describes exactly which location it gets. service.setLocation(this.configuration.getLocation().toString()); In this case, service is an instance variable of a known type, declared within the method. this.configuration comes from being passed in to the class constructor, and is an instance of a class implementing a specific interface (which mandates a public getLocation() method). Hence, the return type of the expression this.configuration.getLocation() is known; specifically in this case, it is a java.net.URL, whereas service.setLocation() wants a String. Since the two types String and URL are not directly compatible, some sort of conversion is required to fit the square peg in the round hole. However, according to the Law of Demeter as cited in Clean Code, a method f in class C should only call methods on C, objects created by or passed as arguments to f, and objects held in instance variables of C. Anything beyond that (the final toString() in my particular case above, unless you consider a temporary object created as a result of the method invocation itself, in which case the whole Law seems to be moot) is disallowed. Is there a valid reasoning why a call like the above, given the constraints listed, should be discouraged or even disallowed? Or am I just being overly nitpicky? If I were to implement a method URLToString() which simply calls toString() on a URL object (such as that returned by getLocation()) passed to it as a parameter, and returns the result, I could wrap the getLocation() call in it to achieve exactly the same result; effectively, I would just move the conversion one step outward. Would that somehow make it acceptable? (It seems to me, intuitively, that it should not make any difference either way, since all that does is move things around a little. However, going by the letter of the Law of Demeter as cited, it would be acceptable, since I would then be operating directly on a parameter to a function.) Would it make any difference if this was about something slightly more exotic than calling toString() on a standard type? When answering, do keep in mind that altering the behavior or API of the type that the service variable is of is not practical. Also, for the sake of argument, let's say that altering the return type of getLocation() is also impractical.

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  • A solution for a PHP website without a framework

    - by lortabac
    One of our customers asked us to add some dynamic functionality to an existent website, made of several static HTML pages. We normally work with an MVC framework (mostly CodeIgniter), but in this case moving everything to a framework would require too much time. Since it is not a big project, not having the full functionality of a framework is not a problem. But the question is how to keep code clean. The solution I came up with is to divide code in libraries (the application's API) and models. So inside HTML there will only be API calls, and readability will not be sacrificed. I implemented this with a sort of static Registry (sorry if I'm wrong, I am not a design pattern expert): <?php class Custom_framework { //Global database instance private static $db; //Registered models private static $models = array(); //Registered libraries private static $libraries = array(); //Returns a database class instance static public function get_db(){ if(isset(self::$db)){ //If instance exists, returns it return self::$db; } else { //If instance doesn't exists, creates it self::$db = new DB; return self::$db; } } //Returns a model instance static public function get_model($model_name){ if(isset(self::$models[$model_name])){ //If instance exists, returns it return self::$models[$model_name]; } else { //If instance doesn't exists, creates it if(is_file(ROOT_DIR . 'application/models/' . $model_name . '.php')){ include_once ROOT_DIR . 'application/models/' . $model_name . '.php'; self::$models[$model_name] = new $model_name; return self::$models[$model_name]; } else { return FALSE; } } } //Returns a library instance static public function get_library($library_name){ if(isset(self::$libraries[$library_name])){ //If instance exists, returns it return self::$libraries[$library_name]; } else { //If instance doesn't exists, creates it if(is_file(ROOT_DIR . 'application/libraries/' . $library_name . '.php')){ include_once ROOT_DIR . 'application/libraries/' . $library_name . '.php'; self::$libraries[$library_name] = new $library_name; return self::$libraries[$library_name]; } else { return FALSE; } } } } Inside HTML, API methods are accessed like this: <?php echo Custom_framework::get_library('My_library')->my_method(); ?> It looks to me as a practical solution. But I wonder what its drawbacks are, and what the possible alternatives.

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  • What HTML and CSS markup is best for SEO for a list of questions (like on Stack Exchange sites)

    - by Oleg9
    On the StackOverflow a question block (in the q-list on the index page and so on) represented by the following html code: <div class="question-summary narrow tagged-interesting" id="question-summary-19832613"> <div onclick="window.location.href='/questions/19832613/how-to-display-only-transit-routesfor-trains-in-google-maps-api'" class="cp"> <div class="votes"> <div class="mini-counts">0</div> <div>votes</div> </div> <div class="status unanswered"> <div class="mini-counts">0</div> <div>answers</div> </div> <div class="views"> <div class="mini-counts">3</div> <div>views</div> </div> </div> <div class="summary"> <h3>...</h3> <div class="tags t-javascript t-google-maps t-google t-google-maps-api-3"> </div> <div class="started"> <a href="/questions/19832613/how-to-display-only-transit-routesfor-trains-in-google-maps-api" class="started-link"><span title="2013-11-07 09:52:29Z" class="relativetime">1 min ago</span></a> <a href="/users/1309392/shirish">Shirish</a> <span class="reputation-score" title="reputation score " dir="ltr">189</span> </div> </div> </div> It uses float positioning. My questions is: Would use of css styled tables be a better choice? (It's a table, isn't it?) Or it just depends on what are you prefer to use and doesn't affect the technical side (search engines or something)? The background information (such as number of views, votes etc.) comes first in the code. And I know that search engines have a limit at viewing each page. So would it better to place div's depending on their importance and then markup them on the page using css methods (like negative margins and absolute positioning)? Or it isn't so important in this instance?

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  • Self-Executing Anonymous Function vs Prototype

    - by Robotsushi
    In Javascript there are a few clearly prominent techniques for create and manage classes/namespaces in javascript. I am curious what situations warrant using one technique vs. the other. I want to pick one and stick with it moving forward. I write enterprise code that is maintained and shared across multiple teams, and I want to know what is the best practice when writing maintainable javascript ? I tend to prefer Self-Executing Anonymous Functions however I am curious what the community vote is on these techniques. Prototype : function obj() { } obj.prototype.test = function() { alert('Hello?'); }; var obj2 = new obj(); obj2.test(); Self-Closing Anonymous Function : //Self-Executing Anonymous Function (function( skillet, $, undefined ) { //Private Property var isHot = true; //Public Property skillet.ingredient = "Bacon Strips"; //Public Method skillet.fry = function() { var oliveOil; addItem( "\t\n Butter \n\t" ); addItem( oliveOil ); console.log( "Frying " + skillet.ingredient ); }; //Private Method function addItem( item ) { if ( item !== undefined ) { console.log( "Adding " + $.trim(item) ); } } }( window.skillet = window.skillet || {}, jQuery )); //Public Properties console.log( skillet.ingredient ); //Bacon Strips //Public Methods skillet.fry(); //Adding Butter & Fraying Bacon Strips //Adding a Public Property skillet.quantity = "12"; console.log( skillet.quantity ); //12 //Adding New Functionality to the Skillet (function( skillet, $, undefined ) { //Private Property var amountOfGrease = "1 Cup"; //Public Method skillet.toString = function() { console.log( skillet.quantity + " " + skillet.ingredient + " & " + amountOfGrease + " of Grease" ); console.log( isHot ? "Hot" : "Cold" ); }; }( window.skillet = window.skillet || {}, jQuery )); //end of skillet definition try { //12 Bacon Strips & 1 Cup of Grease skillet.toString(); //Throws Exception } catch( e ) { console.log( e.message ); //isHot is not defined } I feel that I should mention that the Self-Executing Anonymous Function is the pattern used by the jQuery team. Update When I asked this question I didn't truly see the importance of what I was trying to understand. The real issue at hand is whether or not to use new to create instances of your objects or to use patterns which do not require constructors of the use of the new keyword. I added my own answer, because in my opinion we should make use of patterns which don't use the new keyword. For more information please see my answer.

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  • Oracle Cloud Applications: The Right Ingredients Baked In

    - by yaldahhakim
    v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} Oracle Cloud Applications: The Right Ingredients Baked In Eggs, flour, milk, and sugar. The magic happens when you mix these ingredients together. The same goes for the hottest technologies fast changing how IT impacts our organizations today: cloud, social, mobile, and big data. By themselves they’re pretty good; combining them with a great recipe is what unlocks real transformation power. Choosing the right cloud can be very similar to choosing the right cake. First consider comparing the core ingredients that go into baking a cake and the core design principles in building a cloud-based application. For instance, if flour is the base ingredient of a cake, then rich functionality that spans complete business processes is the base of an enterprise-grade cloud. Cloud computing is more than just consuming an "application as service", and having someone else manage it for you. Rather, the value of cloud is about making your business more agile in the marketplace, and shortening the time it takes to deliver and adopt new innovation. It’s also about improving not only the efficiency at which we communicate but the actual quality of the information shared as well. Data from different systems, like ingredients in a cake, must also be blended together effectively and evaluated through a consolidated lens. When this doesn’t happen, for instance when data in your sales cloud doesn't seamlessly connect with your order management and other “back office” applications, the speed and quality of information can decrease drastically. It’s like mixing ingredients in a strainer with a straw – you just can’t bring it all together without losing something. Mixing ingredients is similar to bringing clouds together, and co-existing cloud applications with traditional on premise applications. This is where a shared services  platform built on open standards and Service Oriented Architecture (SOA) is critical. It’s essentially a cloud recipe that calls for not only great ingredients, but also ingredients you can get locally or most likely already have in your kitchen (or IT shop.) Open standards is the best way to deliver a cost effective, durable application integration strategy – regardless of where your apps are deployed. It’s also the best way to build your own cloud applications, or extend the ones you consume from a third party. Just like using standard ingredients and tools you already have in your kitchen, a standards based cloud enables your IT resources to ensure a cloud works easily with other systems. Your IT staff can also make changes using tools they are already familiar with. Or even more ideal, enable business users to actually tailor their experience without having to call upon IT for help at all. This frees IT resources to focus more on developing new innovative services for the organization vs. run and maintain. Carrying the cake analogy forward, you need to add all the ingredients in before you bake it. The same is true with a modern cloud. To harness the full power of cloud, you can’t leave out some of the most important ingredients and just layer them on top later. This is what a lot of our niche competitors have done when it comes to social, mobile, big data and analytics, and other key technologies impacting the way we do business. The transformational power of these technology trends comes from having a strategy from the get-go that combines them into a winning recipe, and delivers them in a unified way. In looking at ways Oracle’s cloud is different from other clouds – not only is breadth of functionality rich across functional pillars like CRM, HCM, ERP, etc. but it embeds social, mobile, and rich intelligence capabilities where they make the most sense across business processes. This strategy enables the Oracle Cloud to uniquely deliver on all three of these dimensions to help our customers unlock the full power of these transformational technologies.

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  • How can I create a flexible system for tiling a 2D RPG map?

    - by CptSupermrkt
    Using libgdx here. I've just finished learning some of the basics of creating a 2D environment and using an OrthographicCamera to view it. The tutorials I went through, however, hardcoded their tiled map in, and none made mention of how to do it any other way. By tiled map, I mean like Final Fantasy 1, where the world map is a grid of squares, each with a different texture. So for example, I've got a 6 tile x 6 tile map, using the following code: Array<Tile> tiles = new Array<Tile>(); tiles.add(new Tile(new Vector2(0,5), TileType.FOREST)); tiles.add(new Tile(new Vector2(1,5), TileType.FOREST)); tiles.add(new Tile(new Vector2(2,5), TileType.FOREST)); tiles.add(new Tile(new Vector2(3,5), TileType.GRASS)); tiles.add(new Tile(new Vector2(4,5), TileType.STONE)); tiles.add(new Tile(new Vector2(5,5), TileType.STONE)); //... x5 more times. Given the random nature of the environment, for loops don't really help as I have to start and finish a loop before I was able to do enough to make it worth setting up the loop. I can see how a loop might be helpful for like tiling an ocean or something, but not in the above case. The above code DOES get me my final desired output, however, if I were to decide I wanted to move a piece or swap two pieces out, oh boy, what a nightmare, even with just a 6x6 test piece, much less a 1000x1000 world map. There must be a better way of doing this. Someone on some post somewhere (can't find it now, of course) said to check out MapEditor. Looks legit. The question is, if that is the answer, how can I make something in MapEditor and have the output map plug in to a variable in my code? I need the tiles as objects in my code, because for example, I determine whether or not a tile is can be passed through or collided with based on my TileTyle enum variable. Are there alternative/language "native" (i.e. not using an outside tool) methods to doing this?

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  • How to Update Remote Diagnostic Agent (RDA) to Latest Version?

    - by Daniel Mortimer
    Remote Diagnostic Agent (RDA) 4.28 was released on 12th June. Full details can be found in this My Oracle Support documentRDA 4 Release Notes [ID 414970.1]From a Fusion Middleware Core Component, Install and Administration perspective this latest release does not offer any significant new features or changes. However, despite the lack of Fusion Middleware specific new features in version 4.28, Remote Diagnostic Agent still comes as highly recommended. It is incredibly useful problem solving / troubleshooting aid. Support engineers dealing with Service Requests often request RDA output as it collects just about everything you might need to get a view of the state and configuration of the host operating system, network setup and Fusion Middleware components. To find out more take a look at Running RDA Against Oracle Fusion Middleware 11g [ID 853437.1] Getting Started With Remote Diagnostic Agent: Case Study - Oracle WebLogic Server (Video) [ID 1262157.1] Note: While the latter document looks at RDA from the perspective of WebLogic Server, much of the advice given in the videos can be applied to other Fusion Middleware products.Ok, let's get back on track with the topic suggested by the title. If you are already familiar with Remote Diagnostic Agent you may ask the question - 'How do I keep my RDA at the latest version?' The answer is in "Running RDA Against Oracle Fusion Middleware 11g [ID 853437.1]". To quote: There are two methods: 1. Upgrade RDA via OCM (Oracle Configuration Manager) Refer to the advice given in: Remote Diagnostic Agent (RDA) Upgrade README [ID 1309034.1] OR 2. Manually download and upgrade to the latest version. To quote from Remote Diagnostic Agent (RDA) 4 - FAQ [ID 330363.1] +++++++++++++++++++++++++++++++++++++++++++++++++++++++ How do I upgrade my RDA 4.x installation from the prior release? The most simplest and reliable way to upgrade your RDA installation is delete or move your old installation to a new location. Then install the new release into the location you had the prior release installed. If you want to reuse you old setup.cfg file, you can place the older version into the new <rda> directory and it will try to upgrade your setup.cfg to the new features. A second approach is to install the latest RDA into another directory, then if needed copy the old setup.cfg file to the new RDA directory. When the new RDA is run for the first time, it will try to upgrade your setup.cfg to the new features. +++++++++++++++++++++++++++++++++++++++++++++++++++++++ The upgrade method via Oracle Configuration Manager is nice because it allows RDA to be auto updated whenever a new release of RDA is made available (which roughly speaking is every 3 months). However, it does require you to install and configure Oracle Configuration Manager in addition to RDA. A quick guide to Fusion Middleware 11g and OCM can be found in this support document.Configuring OCM in Oracle Fusion Middleware 11g? A Quick and Easy Guide [ID 1096871.1]

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  • HTML5 game programming style

    - by fnx
    I am currently trying learn javascript in form of HTML5 games. Stuff that I've done so far isn't too fancy since I'm still a beginner. My biggest concern so far has been that I don't really know what is the best way to code since I don't know the pros and cons of different methods, nor I've found any good explanations about them. So far I've been using the worst (and propably easiest) method of all (I think) since I'm just starting out, for example like this: var canvas = document.getElementById("canvas"); var ctx = canvas.getContext("2d"); var width = 640; var height = 480; var player = new Player("pic.png", 100, 100, ...); also some other global vars... function Player(imgSrc, x, y, ...) { this.sprite = new Image(); this.sprite.src = imgSrc; this.x = x; this.y = y; ... } Player.prototype.update = function() { // blah blah... } Player.prototype.draw = function() { // yada yada... } function GameLoop() { player.update(); player.draw(); setTimeout(GameLoop, 1000/60); } However, I've seen a few examples on the internet that look interesting, but I don't know how to properly code in these styles, nor do I know if there are names for them. These might not be the best examples but hopefully you'll get the point: 1: Game = { variables: { width: 640, height: 480, stuff: value }, init: function(args) { // some stuff here }, update: function(args) { // some stuff here }, draw: function(args) { // some stuff here }, }; // from http://codeincomplete.com/posts/2011/5/14/javascript_pong/ 2: function Game() { this.Initialize = function () { } this.LoadContent = function () { this.GameLoop = setInterval(this.RunGameLoop, this.DrawInterval); } this.RunGameLoop = function (game) { this.Update(); this.Draw(); } this.Update = function () { // update } this.Draw = function () { // draw game frame } } // from http://www.felinesoft.com/blog/index.php/2010/09/accelerated-game-programming-with-html5-and-canvas/ 3: var engine = {}; engine.canvas = document.getElementById('canvas'); engine.ctx = engine.canvas.getContext('2d'); engine.map = {}; engine.map.draw = function() { // draw map } engine.player = {}; engine.player.draw = function() { // draw player } // from http://that-guy.net/articles/ So I guess my questions are: Which is most CPU efficient, is there any difference between these styles at runtime? Which one allows for easy expandability? Which one is the most safe, or at least harder to hack? Are there any good websites where stuff like this is explained? or... Does it all come to just personal preferance? :)

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  • Is OOP hard because it is not natural?

    - by zvrba
    One can often hear that OOP naturally corresponds to the way people think about the world. But I would strongly disagree with this statement: We (or at least I) conceptualize the world in terms of relationships between things we encounter, but the focus of OOP is designing individual classes and their hierarchies. Note that, in everyday life, relationships and actions exist mostly between objects that would have been instances of unrelated classes in OOP. Examples of such relationships are: "my screen is on top of the table"; "I (a human being) am sitting on a chair"; "a car is on the road"; "I am typing on the keyboard"; "the coffee machine boils water", "the text is shown in the terminal window." We think in terms of bivalent (sometimes trivalent, as, for example in, "I gave you flowers") verbs where the verb is the action (relation) that operates on two objects to produce some result/action. The focus is on action, and the two (or three) [grammatical] objects have equal importance. Contrast that with OOP where you first have to find one object (noun) and tell it to perform some action on another object. The way of thinking is shifted from actions/verbs operating on nouns to nouns operating on nouns -- it is as if everything is being said in passive or reflexive voice, e.g., "the text is being shown by the terminal window". Or maybe "the text draws itself on the terminal window". Not only is the focus shifted to nouns, but one of the nouns (let's call it grammatical subject) is given higher "importance" than the other (grammatical object). Thus one must decide whether one will say terminalWindow.show(someText) or someText.show(terminalWindow). But why burden people with such trivial decisions with no operational consequences when one really means show(terminalWindow, someText)? [Consequences are operationally insignificant -- in both cases the text is shown on the terminal window -- but can be very serious in the design of class hierarchies and a "wrong" choice can lead to convoluted and hard to maintain code.] I would therefore argue that the mainstream way of doing OOP (class-based, single-dispatch) is hard because it IS UNNATURAL and does not correspond to how humans think about the world. Generic methods from CLOS are closer to my way of thinking, but, alas, this is not widespread approach. Given these problems, how/why did it happen that the currently mainstream way of doing OOP became so popular? And what, if anything, can be done to dethrone it?

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  • Inherit one instance variable from the global scope

    - by Julian
    I'm using Curses to create a command line GUI with Ruby. Everything's going well, but I have hit a slight snag. I don't think Curses knowledge (esoteric to be fair) is required to answer this question, just Ruby concepts such as objects and inheritance. I'm going to explain my problem now, but if I'm banging on, just look at the example below. Basically, every Window instance needs to have .close called on it in order to close it. Some Window instances have other Windows associated with it. When closing a Window instance, I want to be able to close all of the other Window instances associated with it at the same time. Because associated Windows are generated in a logical fashion, (I append the name with a number: instance_variable_set(self + integer, Window.new(10,10,10,10)) ), it's easy to target generated windows, because methods can anticipate what assosiated windows will be called, (I can recreate the instance variable name from scratch, and almost query it: instance_variable_get(self + integer). I have a delete method that handles this. If the delete method is just a normal, global method (called like this: delete_window(@win543) then everything works perfectly. However, if the delete method is an instance method, which it needs to be in-order to use the self keyword, it doesn't work for a very clear reason; it can 'query' the correct instance variable perfectly well (instance_variable_get(self + integer)), however, because it's an instance method, the global instances aren't scoped to it! Now, one way around this would obviously be to simply make a global method like this: delete_window(@win543). But I have attributes associated with my window instances, and it all works very elegantly. This is very simplified, but it literally translates the problem exactly: class Dog def speak woof end end def woof if @dog_generic == nil puts "@dog_generic isn't scoped when .woof is called from a class method!\n" else puts "@dog_generic is scoped when .woof is called from the global scope. See:\n" + @dog_generic end end @dog_generic = "Woof!" lassie = Dog.new lassie.speak #=> @dog_generic isn't scoped when .woof is called from an instance method!\n woof #=> @dog_generic is scoped when .woof is called from the global scope. See:\nWoof! TL/DR: I need lassie.speak to return this string: "@dog_generic is scoped when .woof is called from the global scope. See:\nWoof!" @dog_generic must remain as an insance variable. The use of Globals or Constants is not acceptable. Could woof inherit from the Global scope? Maybe some sort of keyword: def woof < global # This 'code' is just to conceptualise what I want to do, don't take offence! end Is there some way the .woof method could 'pull in' @dog_generic from the global scope? Will @dog_generic have to be passed in as a parameter?

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