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  • How to find history of shell commands since machine was created?

    - by Edward Tanguay
    I created an Ubuntu virtualbox machine a couple weeks ago and have been working on projects off and on in it since then. Now I would like to find the syntax of some commands I typed in the terminal a week ago, but I have opened and closed the terminal window and restarted the machine numerous times. How can I get the history command to go back to the first command I typed after I created the machine, or is there another place that all the commands are stored in Ubuntu?

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  • Five hours of Task Flow Overview Recordings Available

    - by Frank Nimphius
    In addition to the ADF Controller task flow documentation in Oracle Fusion Middleware Fusion Developer's Guide for Oracle Application Development Framework 11g Release 1 http://download.oracle.com/docs/cd/E21764_01/web.1111/b31974/partpage3.htm#BABHIIAI The ADF Insider website … http://www.oracle.com/technetwork/developer-tools/adf/learnmore/adfinsider-093342.html … hosts five online videos that explain how to build and work with ADF Controller task flows in Oracle ADF. ADF Task Flow - Overview (Part 1) This 90 minute recording introduces the concept of ADF unbounded and bounded task flows, as well as other ADF Controller features. The session starts with an overview of unbounded task flows, bounded task flows and the different activities that exist for developers to build complex application flows. Exception handling and the Train navigation model is also covered in this first part of a two part series. By example of developing a sample application, the recording guides viewers through building unbounded and bounded task flows. This session is continued in a second part. http://download.oracle.com/otn_hosted_doc/jdeveloper/11gdemos/taskflow-overview-p1/taskflow-overview-p1.html ADF Task Flow - Overview (Part 2) This 75 minute session continues where part 1 ended and completes the sample application that guides viewers through different aspects of unbounded and bounded task flow development. In this recording, memory scopes, save for later, task flow opening in dialogs and remote task flow calls are explained and demonstrated. If you are new to ADF Task Flow, then it is recommended to first watch part 1 of this series to be able to follow the explanation guided by the sample application. http://download.oracle.com/otn_hosted_doc/jdeveloper/11gdemos/taskflow-overview-p2/taskflow-overview-p2.html ADF Region Interaction - An Overview This session covers most of the options that exist for communicating between regions. It briefly discusses what it takes to build regions from bounded task flows before going into details using slides and samples. The following interaction is explained: contextual events, queue action in region, input parameters and PPR, drag and drop, shared Data Controls, parent action and region navigation listener. http://download.oracle.com/otn_hosted_doc/jdeveloper/11gdemos/adf-region-interaction/adf-region-interaction.html ADF Region Interaction - Contextual Events Contextual event is used as a communication channel between a parent view and its contained regions, as well as between regions. By example, this session explains how to set up contextual events, how to define producers and event listeners and how to define the payload message. http://download.oracle.com/otn_hosted_doc/jdeveloper/11gdemos/AdfInsiderContextualEvents/AdfInsiderContextualEvents.html

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  • SDL_BlitSurface segmentation fault (surfaces aren't null)

    - by Trollkemada
    My app is crashing on SDL_BlitSurface() and i can't figure out why. I think it has something to do with my static object. If you read the code you'll why I think so. This happens when the limits of the map are reached, i.e. (iwidth || jheight). This is the code: Map.cpp (this render) Tile const * Map::getTyle(int i, int j) const { if (i >= 0 && j >= 0 && i < width && j < height) { return data[i][j]; } else { return &Tile::ERROR_TYLE; // This makes SDL_BlitSurface (called later) crash //return new Tile(TileType::ERROR); // This works with not problem (but is memory leak, of course) } } void Map::render(int x, int y, int width, int height) const { //DEBUG("(Rendering...) x: "<<x<<", y: "<<y<<", width: "<<width<<", height: "<<height); int firstI = x / TileType::PIXEL_PER_TILE; int firstJ = y / TileType::PIXEL_PER_TILE; int lastI = (x+width) / TileType::PIXEL_PER_TILE; int lastJ = (y+height) / TileType::PIXEL_PER_TILE; // The previous integer division rounds down when dealing with positive values, but it rounds up // negative values. This is a fix for that (We need those values always rounded down) if (firstI < 0) { firstI--; } if (firstJ < 0) { firstJ--; } const int firstX = x; const int firstY = y; SDL_Rect srcRect; SDL_Rect dstRect; for (int i=firstI; i <= lastI; i++) { for (int j=firstJ; j <= lastJ; j++) { if (i*TileType::PIXEL_PER_TILE < x) { srcRect.x = x % TileType::PIXEL_PER_TILE; srcRect.w = TileType::PIXEL_PER_TILE - (x % TileType::PIXEL_PER_TILE); dstRect.x = i*TileType::PIXEL_PER_TILE + (x % TileType::PIXEL_PER_TILE) - firstX; } else if (i*TileType::PIXEL_PER_TILE >= x + width) { srcRect.x = 0; srcRect.w = x % TileType::PIXEL_PER_TILE; dstRect.x = i*TileType::PIXEL_PER_TILE - firstX; } else { srcRect.x = 0; srcRect.w = TileType::PIXEL_PER_TILE; dstRect.x = i*TileType::PIXEL_PER_TILE - firstX; } if (j*TileType::PIXEL_PER_TILE < y) { srcRect.y = 0; srcRect.h = TileType::PIXEL_PER_TILE - (y % TileType::PIXEL_PER_TILE); dstRect.y = j*TileType::PIXEL_PER_TILE + (y % TileType::PIXEL_PER_TILE) - firstY; } else if (j*TileType::PIXEL_PER_TILE >= y + height) { srcRect.y = y % TileType::PIXEL_PER_TILE; srcRect.h = y % TileType::PIXEL_PER_TILE; dstRect.y = j*TileType::PIXEL_PER_TILE - firstY; } else { srcRect.y = 0; srcRect.h = TileType::PIXEL_PER_TILE; dstRect.y = j*TileType::PIXEL_PER_TILE - firstY; } SDL::YtoSDL(dstRect.y, srcRect.h); SDL_BlitSurface(getTyle(i,j)->getType()->getSurface(), &srcRect, SDL::getScreen(), &dstRect); // <-- Crash HERE /*DEBUG("i = "<<i<<", j = "<<j); DEBUG("srcRect.x = "<<srcRect.x<<", srcRect.y = "<<srcRect.y<<", srcRect.w = "<<srcRect.w<<", srcRect.h = "<<srcRect.h); DEBUG("dstRect.x = "<<dstRect.x<<", dstRect.y = "<<dstRect.y);*/ } } } Tile.h #ifndef TILE_H #define TILE_H #include "TileType.h" class Tile { private: TileType const * type; public: static const Tile ERROR_TYLE; Tile(TileType const * t); ~Tile(); TileType const * getType() const; }; #endif Tile.cpp #include "Tile.h" const Tile Tile::ERROR_TYLE(TileType::ERROR); Tile::Tile(TileType const * t) : type(t) {} Tile::~Tile() {} TileType const * Tile::getType() const { return type; } TileType.h #ifndef TILETYPE_H #define TILETYPE_H #include "SDL.h" #include "DEBUG.h" class TileType { protected: TileType(); ~TileType(); public: static const int PIXEL_PER_TILE = 30; static const TileType * ERROR; static const TileType * AIR; static const TileType * SOLID; virtual SDL_Surface * getSurface() const = 0; virtual bool isSolid(int x, int y) const = 0; }; #endif ErrorTyle.h #ifndef ERRORTILE_H #define ERRORTILE_H #include "TileType.h" class ErrorTile : public TileType { friend class TileType; private: ErrorTile(); mutable SDL_Surface * surface; static const char * FILE_PATH; public: SDL_Surface * getSurface() const; bool isSolid(int x, int y) const ; }; #endif ErrorTyle.cpp (The surface can't be loaded when building the object, because it is a static object and SDL_Init() needs to be called first) #include "ErrorTile.h" const char * ErrorTile::FILE_PATH = ("C:\\error.bmp"); ErrorTile::ErrorTile() : TileType(), surface(NULL) {} SDL_Surface * ErrorTile::getSurface() const { if (surface == NULL) { if (SDL::isOn()) { surface = SDL::loadAndOptimice(ErrorTile::FILE_PATH); if (surface->w != TileType::PIXEL_PER_TILE || surface->h != TileType::PIXEL_PER_TILE) { WARNING("Bad tile surface size"); } } else { ERROR("Trying to load a surface, but SDL is not on"); } } if (surface == NULL) { // This if doesn't get called, so surface != NULL ERROR("WTF? Can't load surface :\\"); } return surface; } bool ErrorTile::isSolid(int x, int y) const { return true; }

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  • Basis of definitions

    - by Yttrill
    Let us suppose we have a set of functions which characterise something: in the OO world methods characterising a type. In mathematics these are propositions and we have two kinds: axioms and lemmas. Axioms are assumptions, lemmas are easily derived from them. In C++ axioms are pure virtual functions. Here's the problem: there's more than one way to axiomatise a system. Given a set of propositions or methods, a subset of the propositions which is necessary and sufficient to derive all the others is called a basis. So too, for methods or functions, we have a desired set which must be defined, and typically every one has one or more definitions in terms of the others, and we require the programmer to provide instance definitions which are sufficient to allow all the others to be defined, and, if there is an overspecification, then it is consistent. Let me give an example (in Felix, Haskell code would be similar): class Eq[t] { virtual fun ==(x:t,y:t):bool => eq(x,y); virtual fun eq(x:t, y:t)=> x == y; virtual fun != (x:t,y:t):bool => not (x == y); axiom reflex(x:t): x == x; axiom sym(x:t, y:t): (x == y) == (y == x); axiom trans(x:t, y:t, z:t): implies(x == y and y == z, x == z); } Here it is clear: the programmer must define either == or eq or both. If both are defined, the definitions must be equivalent. Failing to define one doesn't cause a compiler error, it causes an infinite loop at run time. Defining both inequivalently doesn't cause an error either, it is just inconsistent. Note the axioms specified constrain the semantics of any definition. Given a definition of == either directly or via a definition of eq, then != is defined automatically, although the programmer might replace the default with something more efficient, clearly such an overspecification has to be consistent. Please note, == could also be defined in terms of !=, but we didn't do that. A characterisation of a partial or total order is more complex. It is much more demanding since there is a combinatorial explosion of possible bases. There is an reason to desire overspecification: performance. There also another reason: choice and convenience. So here, there are several questions: one is how to check semantics are obeyed and I am not looking for an answer here (way too hard!). The other question is: How can we specify, and check, that an instance provides at least a basis? And a much harder question: how can we provide several default definitions which depend on the basis chosen?

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  • Referencing a picture in another DLL in Silverlight and Windows Phone 7

    - by Laurent Bugnion
    This one has burned me a few times, so here is how it works for future reference: Usually, when I add an Image control into a Silverlight application, and the picture it shows is local (as opposed to loaded from the web), I set the picture’s Build Action to Content, and the Copy to Output Directory to Copy if Newer. What the compiler does then is to copy the picture to the bin\Debug folder, and then to pack it into the XAP file. In XAML, the syntax to refer to this local picture is: <Image Source="/Images/mypicture.jpg" Width="100" Height="100" /> And in C#: return new BitmapImage(new Uri( "/Images/mypicture.jpg", UriKind.Relative)); One of the features of Silverlight is to allow referencing content (pictures, resource dictionaries, sound files, movies etc…) located in a DLL directly. This is very handy because just by using the right syntax in the URI, you can do this in XAML directly, for example with: <Image Source="/MyApplication;component/Images/mypicture.jpg" Width="100" Height="100" /> In C#, this becomes: return new BitmapImage(new Uri( "/MyApplication;component/Images/mypicture.jpg", UriKind.Relative)); Side note: This kind of URI is called a pack URI and they have been around since the early days of WPF. There is a good tutorial about pack URIs on MSDN. Even though it refers to WPF, it also applies to Silverlight Side note 2: With the Build Action set to Content, you can rename the XAP file to ZIP, extract all the files, change the picture (but keep the same name), rezip the whole thing and rename again to XAP. This is not possible if the picture is embedded in an assembly! So what’s the catch? Well the catch is that this does not work if you set the Build Action to Content. It’s actually pretty simple to explain: The pack URI above tells the Silverlight runtime to look within an assembly named MyOtherAssembly for a file named MyPicture.jpg in the Images folder. If the file is included as Content, however, it is not in the assembly. Silverlight does not find it, and silently returns nothing. The image is not displayed. And the fix? The fix, for class libraries, is to set the Build Action to Resource. With this, the picture will gets packed into the DLL itself. Of course, this will increase the size of the DLL, and any change to the picture will require recompiling the class library, which is not ideal. But in the cases where you want to distribute pictures (icons etc) together with a plug-in assembly, well, this is a good way to have everything in the same place Happy coding, Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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  • Embedded Model Designing -- top down or bottom up?

    - by Jeff
    I am trying to learn RoR and develop a webapp. I have a few models I have thought of for this app, and they are fairly embedded. For example (please excuse my lack of RoR syntax): Model: textbook title:string type:string has_many: chapters Model: chapter content:text has_one: review_section Model: review_section title:string has_many: questions has_many: answers , through :questions Model: questions ... Model: answers ... My question is, with the example I gave, should I start at the top model (textbook) or the bottom most (answers)?

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  • Render an image with layers for shadows /reflections, object and ground in 3D Studio Max?

    - by Bernd Plontsch
    I have a scene with a simple object standing on the ground in the center. This object has shadows and reflections on the ground. How can I render an image containing 3 separate layers for The object The ground The reflection / shadow on the ground Which format do I use for this? (It should include all 3 layers + I should be able to enable/disable them in Photoshop) How do I define or prepare those layers for being rendering as image layers?

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  • No Android SDK, neither Java found

    - by Alex
    I have Java installed correctly, I did it by the manual http://www.wikihow.com/Install-Oracle-Java-on-Ubuntu-Linux I also installed Android SDK. However when I try to create a new Project IntelliJ Idea 12 and specify Project SDk choosing New - /home/alex/android-sdk-linux , it says me No Java SDK of appropriate version found. In addition to the Android SDK, you need to define a JSDK 1.5, 1.6 or 1.7 What did I miss?

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  • F# Objects &ndash; Integrating with the other .Net Languages &ndash; Part 1

    - by MarkPearl
    In the next few blog posts I am going to explore objects in F#. Up to now, my dabbling in F# has really been a few liners and while I haven’t reached the point where F# is my language of preference – I am already seeing the benefits of the language when solving certain types of programming problems. For me I believe that the F# language will be used in a silo like architecture and that the real benefit of having F# under your belt is so that you can solve problems that F# lends itself towards and then interact with other .Net languages in doing the rest. When I was still very new to the F# language I did the following post covering how to get F# & C# to talk to each other. Today I am going to use a similar approach to demonstrate the structure of F# objects when inter-operating with other languages. Lets start with an empty F# class … type Person() = class end   Very simple, and all we really have done is declared an object that has nothing in it. We could if we wanted to make an object that takes a constructor with parameters… the code for this would look something like this… type Person =     {         Firstname : string         Lastname : string     }   What’s interesting about this syntax is when you try and interop with this object from another .Net language like C# - you would see the following…   Not only has a constructor been created that accepts two parameters, but Firstname and Lastname are also exposed on the object. Now it’s important to keep in mind that value holders in F# are immutable by default, so you would not be able to change the value of Firstname after the construction of the object – in C# terms it has been set to readonly. One could however explicitly state that the value holders were mutable, which would then allow you to change the values after the actual creation of the object. type Person = { mutable Firstname : string mutable Lastname : string }   Something that bugged me for a while was what if I wanted to have an F# object that requires values in its constructor, but does not expose them as part of the object. After bashing my head for a few moments I came up with the following syntax – which achieves this result. type Person(Firstname : string, Lastname : string) = member v.Fullname = Firstname + " " + Lastname What I haven’t figured out yet is what is the difference between the () & {} brackets when declaring an object.

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  • Data Auditor by Example

    - by Jinjin.Wang
    OWB has a node Data Auditors under Oracle Module in Projects Navigator. What is data auditor and how to use it? I will give an introduction to data auditor and show its usage by examples. Data auditor is an important tool in ensuring that data quality levels meet business requirements. Data auditor validates data against a set of data rules to determine which records comply and which do not. It gathers statistical metrics on how well the data in a system complies with a rule by auditing and marking how many errors are occurring against the audited table. Data auditors are typically scheduled for regular execution as part of a process flow, to monitor the quality of the data in an operational environment such as a data warehouse or ERP system, either immediately after updates like data loads, or at regular intervals. How to use data auditor to monitor data quality? Only objects with data rules can be monitored, so the first step is to define data rules according to business requirements and apply them to the objects you want to monitor. The objects can be tables, views, materialized views, and external tables. Secondly create a data auditor containing the objects. You can configure the data auditor and set physical deployment parameters for it as optional, which will be used while running the data auditor. Then deploy and run the data auditor either manually or as part of the process flow. After execution, the data auditor sets several output values, and records that are identified as not complying with the defined data rules contained in the data auditor are written to error tables. Here is an example. We have two tables DEPARTMENTS and EMPLOYEES (see pic-1 and pic-2. Click here for DDL and data) imported into OWB. We want to gather statistical metrics on how well data in these two tables satisfies the following requirements: a. Values of the EMPLOYEES.EMPLOYEE_ID attribute are three-digit numbers. b. Valid values for EMPLOYEES.JOB_ID are IT_PROG, SA_REP, SH_CLERK, PU_CLERK, and ST_CLERK. c. EMPLOYEES.EMPLOYEE_ID is related to DEPARTMENTS.MANAGER_ID. Pic-1 EMPLOYEES Pic-2 DEPARTMENTS 1. To determine legal data within EMPLOYEES or legal relationships between data in different columns of the two tables, firstly we define data rules based on the three requirements and apply them to tables. a. The first requirement is about patterns that an attribute is allowed to conform to. We create a Domain Pattern List data rule EMPLOYEE_PATTERN_RULE here. The pattern is defined in the Oracle Database regular expression syntax as ^([0-9]{3})$ Apply data rule EMPLOYEE_PATTERN_RULE to table EMPLOYEES.

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  • How to keep balance / Unlock items / achievement rules

    - by Mark Knol
    I'm working on an engine for a game, too learn javascript and just because its fun. I'm a flashdeveloper, I know how to build websites. Now making games is a different challenge, javascript is a challenge, but I'd love to learn how to structure code and what patterns are common. I dont mind if the game ever finish, I'm mostly interested in the programming part of it. I dont have a particular endresult in mind, so I'll see where it takes me. I currently have a system where you can buy items. The items cost a specified amount of gold, silver, diamonds etc. When you have selected and bought the item, it takes time before getting rewarded. When time is over, you are getting rewarded with other properties (gold, energy, diamonds). For example, you can buy an apple for 50gold, It takes a minute, you get rewarded with 75energy. Or if you take a run, it cost 50energy, it takes 5minutes, reward is 25gold and 25silver. These definitions is what i call actions. Currently I already have a system where this already works and I can define as much actions with as much properties as I want. The definitions I have kinda looks like this: {id:101, category:544, onInit:{gold:-75}, onComplete:{energy:75}, time:2000, name:"Apple", locked: false} {id:102, category:544, onInit:{gold:-135}, onComplete:{energy:145}, time:2000, name:"Banana", locked: false} {id:106, category:302, onInit:{energy:-50, power: -25}, onComplete:{gold:100, diamonds:2}, time:10000, name:"Run", locked: false} {id:107, category:302, onInit:{energy:-70, silver: -55}, onComplete:{gold:100}, time:10000, name:"Dance", locked: false} {id:108, category:302, onInit:{energy:-230, power: -355}, onComplete:{gold:70, silver:70}, time:10000, name:"Fitness", locked: false} Now, I would love to add a system where I can lock/unlock the actions using achievement rules. Lets say, if you buy 10 apples, you unlock a new action, like bananas which cost more, and reward more. In the future I maybe want to restrict achievements and actions to levels. I am kinda stuck how to structure this. I have 2 questions: Which patterns are used to define achievements? How/where are they defined? Should it be part of the action, or should it be a separate controller? Is it a good idea to register all completed actions to it? I think I want multiple types of achievement rules, Id love to hear some ideas how to develop it. How do you create/find a good balance, so the user does not get stuck or can cheat by repeat a pattern of actions to get too much rewards. I know there is not a simple answer and i'm lacking of a good game-concept, but I wonder if anyone created such a game and how you dealed and played with it.

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  • Renaming Photos with digiKam

    <b>Scribbles and Snaps:</b> "Of course, renaming each and every photo by hand is not particularly practical, especially if you take dozens or even hundreds of photos each day. This is when digiKam's Rename feature can come in rather handy. You can use it to define rather advanced renaming rules and apply them to multiple photos in one fell swoop."

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  • What is required for a scope in an injection framework?

    - by johncarl
    Working with libraries like Seam, Guice and Spring I have become accustomed to dealing with variables within a scope. These libraries give you a handful of scopes and allow you to define your own. This is a very handy pattern for dealing with variable lifecycles and dependency injection. I have been trying to identify where scoping is the proper solution, or where another solution is more appropriate (context variable, singleton, etc). I have found that if the scope lifecycle is not well defined it is very difficult and often failure prone to manage injections in this way. I have searched on this topic but have found little discussion on the pattern. Is there some good articles discussing where to use scoping and what are required/suggested prerequisites for scoping? I interested in both reference discussion or your view on what is required or suggested for a proper scope implementation. Keep in mind that I am referring to scoping as a general idea, this includes things like globally scoped singletons, request or session scoped web variable, conversation scopes, and others. Edit: Some simple background on custom scopes: Google Guice custom scope Some definitions relevant to above: “scoping” - A set of requirements that define what objects get injected at what time. A simple example of this is Thread scope, based on a ThreadLocal. This scope would inject a variable based on what thread instantiated the class. Here's an example of this: “context variable” - A repository passed from one object to another holding relevant variables. Much like scoping this is a more brute force way of accessing variables based on the calling code. Example: methodOne(Context context){ methodTwo(context); } methodTwo(Context context){ ... //same context as method one, if called from method one } “globally scoped singleton” - Following the singleton pattern, there is one object per application instance. This applies to scopes because there is a basic lifecycle to this object: there is only one of these objects instantiated. Here's an example of a JSR330 Singleton scoped object: @Singleton public void SingletonExample{ ... } usage: public class One { @Inject SingeltonExample example1; } public class Two { @Inject SingeltonExample example2; } After instantiation: one.example1 == two.example2 //true;

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  • "The disk drive for / is not ready yet or not present" message on boot

    - by MHS
    After upgrading my Ubuntu machine from ver. 11.10 to 12.04, I get the following error and the machine stop working before any graphical environment: ** (plymouthd:357): WARNING **: Command line `dbus-launch --autolaunch=530c973a1fe4d1e1e6bd... --binary-syntax --close-stderr' exited with non-zero exit status 1: Autolaunch error: X11 initialization failed.\n udevd[397]: specified group 'colord' unknown The disk drive for / is not ready yet or not present. Continue to wait, or Press S to skip mounting or M for manual recovery. Any help appreciated.

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  • ReSharper 5.0s LINQ Refactoring Continues to be Amazing!

    In this post, well take a straight forward procedure based set of code and convert it to LINQ using a ReSharper from JetBrains suggestion.   Ive found that in general, when I do things with foreach syntax, there is often a better way in Linq to do this.  The better does not jump out [...]...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • How to: Apply themes using Server Object Model in SharePoint 2013 Preview

    - by panjkov
    One of new functionalities introduced in SharePoint 2013 Preview is new theming engine. Themes that are managed by this new engine don’t use Office Theme .thmx format and can’t be created using PowerPoint like it was case before. New themes are based on set of xml files stored in Theme Gallery “15” subfolder (on relative path _catalogs/theme/15): .spcolor files  which define color palettes for components of SharePoint interface .spfont files which contain set of predefined font schemes. There...(read more)

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  • Xml Literals

    XML Literals allow you to use XML syntax in your code. It’s easy to work with XML files this way, since you have that Tags in the code, but it’s also quicker to access information rather then the traditional methods.

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  • Xml Literals

    XML Literals allow you to use XML syntax in your code. Its easy to work with XML files this way, since you have that Tags in the code, but its also quicker to access information rather then the traditional methods....Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Can Scala be considered a functional superset of Java?

    - by Giorgio
    Apart from the differences in syntax, can Scala be considered a superset of Java that adds the functional paradigm to the object-oriented paradigm? Or are there any major features in Java for which there is no direct Scala equivalent? With major features I mean program constructs that would force me to heavily rewrite / restructure my code, e.g., if I had to port a Java program to Scala. Or can I expect that, given a Java program, I can port it to Scala almost line-by-line?

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  • Subterranean IL: Exception handling 1

    - by Simon Cooper
    Today, I'll be starting a look at the Structured Exception Handling mechanism within the CLR. Exception handling is quite a complicated business, and, as a result, the rules governing exception handling clauses in IL are quite strict; you need to be careful when writing exception clauses in IL. Exception handlers Exception handlers are specified using a .try clause within a method definition. .try <TryStartLabel> to <TryEndLabel> <HandlerType> handler <HandlerStartLabel> to <HandlerEndLabel> As an example, a basic try/catch block would be specified like so: TryBlockStart: // ... leave.s CatchBlockEndTryBlockEnd:CatchBlockStart: // at the start of a catch block, the exception thrown is on the stack callvirt instance string [mscorlib]System.Object::ToString() call void [mscorlib]System.Console::WriteLine(string) leave.s CatchBlockEnd CatchBlockEnd: // method code continues... .try TryBlockStart to TryBlockEnd catch [mscorlib]System.Exception handler CatchBlockStart to CatchBlockEnd There are four different types of handler that can be specified: catch <TypeToken> This is the standard exception catch clause; you specify the object type that you want to catch (for example, [mscorlib]System.ArgumentException). Any object can be thrown as an exception, although Microsoft recommend that only classes derived from System.Exception are thrown as exceptions. filter <FilterLabel> A filter block allows you to provide custom logic to determine if a handler block should be run. This functionality is exposed in VB, but not in C#. finally A finally block executes when the try block exits, regardless of whether an exception was thrown or not. fault This is similar to a finally block, but a fault block executes only if an exception was thrown. This is not exposed in VB or C#. You can specify multiple catch or filter handling blocks in each .try, but fault and finally handlers must have their own .try clause. We'll look into why this is in later posts. Scoped exception handlers The .try syntax is quite tricky to use; it requires multiple labels, and you've got to be careful to keep separate the different exception handling sections. However, starting from .NET 2, IL allows you to use scope blocks to specify exception handlers instead. Using this syntax, the example above can be written like so: .try { // ... leave.s EndSEH}catch [mscorlib]System.Exception { callvirt instance string [mscorlib]System.Object::ToString() call void [mscorlib]System.Console::WriteLine(string) leave.s EndSEH}EndSEH:// method code continues... As you can see, this is much easier to write (and read!) than a stand-alone .try clause. Next time, I'll be looking at some of the restrictions imposed by SEH on control flow, and how the C# compiler generated exception handling clauses.

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  • I can't install Ubuntu 12.04.1 on iMac G5

    - by user89004
    So, I have this iMac G5 that doesn't have iSight, only a small light sensor I think undernieth, machine model 8.2. I tried burning a Ubuntu 12.04.1 PowerPC 64bit .iso to a cd but the computer just won't boot it, I don't know why. Next I tried with a USB but it wouldn't let me boot that either, I created the usb on my dad's win7 laptop as the process was way easier than on freakin Mac or Ubuntu (no command typing AT ALL on windows) I'm able to get into openfirmware and type boot usb and it does show some weird writing that scrolls so fast I can't see anything and then it just gives me this huge no sign like a stop sign and freezez. The sign is grey and the line in the middle is tilted towards the left. An other issue I'm having with hdiutil is that I can't convert the stupid .iso I just downloaded into a .img because the file keeps on dissapearing right when it's done converting it. I used the syntax from Ubuntu support how to create a bootable usb drive under Mac OS X. I even didn't include the 2 stupid ~ that are shown in the syntax that are completly worthless, God only know why they put them there, and I even tried running the whole thing as root with sudo su before the command. The funny thing is that if I convert something smaller it works. The command I was using is hdiutil convert -format UDRW -o /path/to/target.img /path/to/ubuntu.iso I even tried hdiutil convert /path/to/ubuntu.iso -format UDRW -o /path/to/target.img but the same thing happens, the dummy .img.dmg file dissapears when the conversion is done no matter where I set the output file to go. I have tried several different folders, the same thing happens with all of them. I also tried burning a Ubuntu mini iso on a cd, can't remember if it was 11.10 or 12.10 but even thoguh holding c when the iMac boots up does show me the cd and I can boot from it, I get this weird error upon hitting install, it says something like invalid memory access, release keys and error strings I can't read. I don't have any original DVDs from this iMac and can't run hardware diagnostics. WHatever option I try at the command prompt from the mini ubuntu cd I get the same result, error code and openfirmware backdrop that's frozen. I noticed that the pen drive I created on my dads Win7 laptop is formated with MS-DOS but I can still mount it no problem, so it shouldn't have a problem booting it, right? I used the advice on ubuntu.com to make it, from here. Also, my partition is HFS+ so I can't use it as a hard drive and boot from it. I don' have 2 partitions either, just one HDD, one partition. Please help!!!

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  • JavaScript Class Patterns &ndash; In CoffeeScript

    - by Liam McLennan
    Recently I wrote about JavaScript class patterns, and in particular, my favourite class pattern that uses closure to provide encapsulation. A class to represent a person, with a name and an age, looks like this: var Person = (function() { // private variables go here var name,age; function constructor(n, a) { name = n; age = a; } constructor.prototype = { toString: function() { return name + " is " + age + " years old."; } }; return constructor; })(); var john = new Person("John Galt", 50); console.log(john.toString()); Today I have been experimenting with coding for node.js in CoffeeScript. One of the first things I wanted to do was to try and implement my class pattern in CoffeeScript and then see how it compared to CoffeeScript’s built-in class keyword. The above Person class, implemented in CoffeeScript, looks like this: # JavaScript style class using closure to provide private methods Person = (() -> [name,age] = [{},{}] constructor = (n, a) -> [name,age] = [n,a] null constructor.prototype = toString: () -> "name is #{name} age is #{age} years old" constructor )() I am satisfied with how this came out, but there are a few nasty bits. To declare the two private variables in javascript is as simple as var name,age; but in CoffeeScript I have to assign a value, hence [name,age] = [{},{}]. The other major issue occurred because of CoffeeScript’s implicit function returns. The last statement in any function is returned, so I had to add null to the end of the constructor to get it to work. The great thing about the technique just presented is that it provides encapsulation ie the name and age variables are not visible outside of the Person class. CoffeeScript classes do not provide encapsulation, but they do provide nicer syntax. The Person class using native CoffeeScript classes is: # CoffeeScript style class using the class keyword class CoffeePerson constructor: (@name, @age) -> toString: () -> "name is #{@name} age is #{@age} years old" felix = new CoffeePerson "Felix Hoenikker", 63 console.log felix.toString() So now I have a trade-off: nice syntax against encapsulation. I think I will experiment with both strategies in my project and see which works out better.

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  • SOA Suite Integration: Part 3: Loading files

    - by Anthony Shorten
    One of the most common scenarios in SOA Integration is the loading of a file into the product from an external source. In Oracle SOA Suite there is a File Adapter that can process many file types into your BPEL process. For this example I will use the File Adapter to load a file of user and emails to update the user object within the Oracle Utilities Application Framework. Remember you can repeat this process with other objects and other file types. Again I am illustrating the ease of integration. The first thing is to create an empty BPEL process that will hold our flow. In Oracle JDeveloper this can be achieved by specifying the Define Service Later template (as other templates have predefined inputs and outputs and in this case we want to specify those). So I will create simpleFileLoad process to house our process. You will start with an empty canvas so you need to first specify the load part of the process using the File Adapter. Select the File Adapter from the Component Palette under BPEL Services and drag and drop it to the left side Partner Links (left is input). You name the Service. In this case I chose LoadFile. Press Next. We will define the interface as part of the wizard so select Define from operation and schema (specified later). Press Next. We are going to choose Read File to denote that we will read the file and specify the default Operation Name as Read. Press Next. The next step is to tell the Adapter the location of the files, how to process them and what to do with them after they have been processed. I am using hardcoded locations in this example but you can have logical locations as well. Press Next. I am now going to tell the adapter how to recognize the files I want to load. In my case I am using CSV files and more importantly I am tell the adapter to run the process for each record in the file it encounters. Press Next. Now, I tell the adapter how often I want to poll for the files. I have taken the defaults. Press Next. At this stage I have no explanation of the format of the input. So I am going to invoke the Native Format Wizard which will guide me through the process of creating the file input format. Clicking the purple cog icon will start the wizard. After an introduction screen (not shown), you specify the format of the input file. The File Adapter supports multiple format types. For this example, I will use Delimited as I am going to load a CSV file. Press Next. The best way for the wizard to work is with a sample. I have a sample file and the wizard will ask how much of the file to use as a template. I will use the defaults. Note: If you are using a language that has other languages other than US-ASCII, it is at this point you specify the character set to use.  Press Next. The sample contains multiple instances of a single record type. The wizard supports complex types as well. We will use the appropriate setting for our file. Press Next. You have to specify the file element and the record element. This will be used by the input wizard to translate the CSV data into an XML structure (this will make sense later). I am using LoadUsers as my file delimiter (root element) and User Record as my record root element. Press Next. As the file is CSV the delimiter is "," so I will also specify that the End Of Line (EOL) indicator indicates the end of a record. Press Next. Up until this point your have not given the columns their names. In my case my sample includes the column names in the first record. This is not always the case but you can specify the names and formats of columns in this dialog (not shown). Press Next. The wizard now generates the schema for the input file. You can specify a name for the schema. I have used userupdate.xsd. We want to verify the schema so press Test. You can test the schema by specifying an input sample. and pressing the green play button. You will see the delimiters you specified earlier for the file and the records. Press Ok to continue. A confirmation screen will be displayed showing you the location of the schema in your project. Press Finish to return to the File Adapter configuration. You will now see the schema and elements prepopulated from the wizard. Press Next. The File Adapter configuration is now complete. Press Finish. Now you need to receive the input from the LoadFile component so we need to place a Receive node in the BPEL process by drag and dropping the Receive component from the Component Palette under BPEL Constructs onto the BPEL process. We link the receive process with the LoadFile component by dragging the left most connect node of the Receive node to the LoadFile component. Once the link is established you need to name the Receive node appropriately and as in the post of the last part of this series you need to generate input variables for the BPEL process to hold the input records in. You need to now add the product Web Service. The process is the same as described in the post of the last part of this series. You drop the Web Service BPEL Service onto the right side of the process and fill in the details of the WSDL URL . You also have to add an Invoke node to call the service and generate the input and outputs variables for the call in the Invoke node. Now, to get the inputs from File to the service. You have to use a Transform (you can use an Assign action but a Transform action is more flexible). You drag and drop the Transform component from the Component Palette under Oracle Extensions and place it between the Receive and Invoke nodes. We name the Transform Node, Mapper File and associate the source of the mapping the schema from the Receive node and the output will be the input variable from the Invoke node. We now build the transform. We first map the user and email attributes by drag and drop the elements from the left to the right. The reason we needed to use the transform is that we will be telling the AS-User service that we want to issue an update action. Remember when we registered the service we actually used Read as the default. If we do not otherwise inform the service to use the Update action it will use the Read action instead (which is not desired). To specify the update action you need to click on the transactionType node on the right and select Set Text to set the action. You need to specify the transactionType of UPD (for update). The mapping is now complete. The final BPEL process is ready for deployment. You then deploy the BPEL process to the server and to test the service by simply dropping a file, in the same pattern/name as you specified, in the directory you specified in the File Adapter. You will see each record as a separate instance entry in the Fusion Middleware Control console. You can now load files into the product. You can repeat this process for each type of file to process. While this was a simple example it illustrates the method of loading data can be achieved using SOA Suite in conjunction with our products.

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  • When are Private Clouds a Good Idea?

    This article is taken from the book "The Cloud at Your Service." The authors define the term private cloud and discuss issues to consider before opting for private clouds and concerns about deploying a private cloud.

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