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• The Latest Major Release of AutoVue is Now Available!

  - by Pam Petropoulos

  Click here to read the full press release. To learn more about AutoVue 20.2, check out the What's New in AutoVue 20.2 Datasheet AutoVue 20.2 continues to set the standard for enterprise level visualization with Augmented Business Visualization, a new paradigm which reconciles information and business data from multiple sources into a single view, providing rich and actionable visual decision-making environments. The release also includes; capabilities that enhance end-to-end approval workflow; solutions to visually enable the mobile workforce; and support for the latest manufacturing and high tech formats.     New capabilities in release 20.2 include: ·         Enhancements to the Augmented Business Visualization framework o    Creation of 2D hotspots has been extended in 2D drawings, PDF and image files and can now be defined as regional boxes, rather than just text strings o    New 3D Hotspot links in models and drawings. Parts or components of 3D models can be selected to create hotspot links. ·         Enhanced end-to-end approval workflows with digital stamping and batch stamping improvements ·         Solutions that visually enable the mobile workforce and extend enterprise visualization to mobile devices, including iPads through OVDI (Oracle Virtual Desktop Infrastructure) ·         Enhancements to AutoVue enterprise readiness: reliability and performance improvements, as well as security enhancements which adhere to Oracle’s Software Security Assurance standards ·         Timely support for new MCAD, ECAD, and Office formats ·         New 20.2 versions of AutoVue Document Print Services and Integration SDK (iSDK) ·         New Dutch language availability   The press release also contains terrific supporting quotes from AutoVue customers and partners.        “AutoVue’s stamping enhancements will greatly benefit our building permit management processes,” said Ties Kremer, Information Manager, Noordenveld Municipality, Netherlands. “The ability to batch stamp documents will speed up our approval processes, enable us to save time and money, and help us meet our regulatory compliance obligations.”          “AutoVue provides our non-technical teams in marketing and sales with access to customer order requirements and supporting CAD documents and drawings,” said James Lim, Regional Technical Systems Manager at Molex Incorporated. “AutoVue 20.2 has enabled us to refine our quotation process, and reduce order errors.”         “We are excited about our use of AutoVue’s Augmented Business Visualization framework, which will offer Meridian users enhanced access to related technical documentation,” said Edwin van Dijk, Director of Product Management, BlueCielo.  “By including AutoVue’s new regional hotspot capabilities within BlueCielo Meridian Enterprise, the context of engineering information is carried over into the visual representation of complex assets, thereby helping us to improve productivity and operational excellence.”    

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• Encrypted off-site data storage

  - by Dan

  My business has a rather unique problem. We work in China and we want to implement a file server paradigm which does not store any files locally, but rather in a server overseas. Applications would be saved onto our local machines, but data would be loaded directly into memory from the cloud, e.g. I load a docx into word at the beginning of the day, saving periodically to the cloud as I work on it, and turn off my computer at night, with nothing saved locally. Considering recent events, we worry about being raided by the Chinese authorities, and although all our data is encrypted, it would not be hard for the authorities to force us to give up the keys. So the goal is not to have anything compromising physically in China. We have about 20 computers, and we need an authenticated, encrypted connection with this overseas file server. A system with Active-Directory-like permissions would be best, so that only management can read or write to certain files, or workers can only access files that relate to their projects, and to which all access can be cut off should the need arise. The file server itself would also need to be encrypted. And for convenience, it would be nice if this system was integrated with each computer's file explorer (like skydrive or dropbox does, but, again, without saving a copy locally), rather than through a browser. I can't find any solution online. Does anyone know of a service that does this? Otherwise I'll have to do it myself (which kinda sounds fun, but I don't really have the time), and I'm not sure where to start. Amazon maybe. But the protocols that offices would use on their intranet typically aren't encrypted; we need all traffic securely tunneled out of the country. Each computer already has a VPN to a server in California, but I'm unsure whether it would be efficient to pipe file transfers through it. Let me know if anyone has any ideas. And this is my first post; feel free say whether this question is inappropriate/needs to be posted elsewhere.

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• Surface development: it&rsquo;s just like software development

  - by Dennis Vroegop

  Surface is magic. Everyone using it seems to think that way. And I have to be honest, after working for almost 2 years with the platform I still get that special feeling the moment I turn on the unit to do some more work. The whole user experience, the rich environment of the SDK, the touch, even the look and feel of the Surface environment is so much different from the stuff I’ve been working on all my career that I am still bewildered by it. But… and this is a big but.. in the end we’re still talking about a computer and that needs software to become useful. Deep down the magic of the Surface unit there is a PC somewhere, running Windows Vista and the .net framework 3.5. When you write that magic software that makes the platform come alive you’re still working with .net, WPF/XNA, C#, VB.Net and all those other tools and technologies you know so well. Sure, the whole user experience is different from what you’ve known. And the way of thinking about users, their interaction and the positioning of screen elements requires a whole new paradigm. And that takes time. It took me about half a year before I had the feeling I got it nailed down. But when that moment came (about 18 months ago…) I realized that everything I had learned so far on software development still is true when it comes to Surface. The last 6 months I have been working with some people with a different background to start a new company. The idea was that the new company would be focussing on Surface and Surface only. These people come from a marketing background and had some good ideas for some applications. And I have to admit: their ideas were good. Very good. Where it all fell down of course is that these ideas need to be implemented in a piece of software. And creating great software takes skilled developers and a lot of time and money. That’s where things went wrong: the marketing guys didn’t realize and didn’t want to realize that software development is a job that takes skill. You can’t just hire a bunch of developers and expect them to deliver the best sort of software, especially not when it comes to Surface. I tried to explain that yes, their User Interface in Photoshop looked great, but no: I couldn’t develop an application like that in a weeks time. Even worse: the while backend of the software (WCF for communications, SQL Server for the database, etc) would take a lot more time than the frontend. They didn’t understand. It took them a couple of days to drawn the UI in Photoshop so in Blend I should be able to build the software in about the same amount of time. Well, you and I know that it doesn’t work that way. Software is hard to write, and even harder to write well, and it takes skill and dedication. It’s not something you can do as fast as you can draw a mock up for a Surface application in Photohop. The same holds true for web applications of course. A lot of designers there fail to appreciate the hard work that goes into writing the plumbing for a good web app that can handle thousands of users. Although the UI is very important, it’s not all there is to it. And in Surface development this is the same. The UI should create the feeling of magic, but the software behind it is what makes it come alive. And that takes time. A lot of time. So brush of you skills and don’t throw them away if you start developing for Surface. Because projects (and colaborations) can fail there as hard as they can in any other area of software development. On a side note: we decided to stop the colaboration (something the other parties involved didn’t appreciate and were very angry about) and decided to hire a designer for the Surface projects. The focus is back where it belongs: on the software development we know so well and have been doing very well for 13 years. UI is just a part of the whole project and not the end product. So my company Detrio is still going strong when it comes to develivering Surface solutions but once again from a technological background, not a marketing background.

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• ODI 12c's Mapping Designer - Combining Flow Based and Expression Based Mapping

  - by Madhu Nair

  post by David Allan ODI is renowned for its declarative designer and minimal expression based paradigm. The new ODI 12c release has extended this even further to provide an extended declarative mapping designer. The ODI 12c mapper is a fusion of ODI's new declarative designer with the familiar flow based designer while retaining ODI’s key differentiators of: Minimal expression based definition, The ability to incrementally design an interface and to extract/load data from any combination of sources, and most importantly Backed by ODI’s extensible knowledge module framework. The declarative nature of the product has been extended to include an extensible library of common components that can be used to easily build simple to complex data integration solutions. Big usability improvements through consistent interactions of components and concepts all constructed around the familiar knowledge module framework provide the utmost flexibility. Here is a little taster: So what is a mapping? A mapping comprises of a logical design and at least one physical design, it may have many. A mapping can have many targets, of any technology and can be arbitrarily complex. You can build reusable mappings and use them in other mappings or other reusable mappings. In the example below all of the information from an Oracle bonus table and a bonus file are joined with an Oracle employees table before being written to a target. Some things that are cool include the one-click expression cross referencing so you can easily see what's used where within the design. The logical design in a mapping describes what you want to accomplish  (see the animated GIF here illustrating how the above mapping was designed) . The physical design lets you configure how it is to be accomplished. So you could have one logical design that is realized as an initial load in one physical design and as an incremental load in another. In the physical design below we can customize how the mapping is accomplished by picking Knowledge Modules, in ODI 12c you can pick multiple nodes (on logical or physical) and see common properties. This is useful as we can quickly compare property values across objects - below we can see knowledge modules settings on the access points between execution units side by side, in the example one table is retrieved via database links and the other is an external table. In the logical design I had selected an append mode for the integration type, so by default the IKM on the target will choose the most suitable/default IKM - which in this case is an in-built Oracle Insert IKM (see image below). This supports insert and select hints for the Oracle database (the ANSI SQL Insert IKM does not support these), so by default you will get direct path inserts with Oracle on this statement. In ODI 12c, the mapper is just that, a mapper. Design your mapping, write to multiple targets, the targets can be in the same data server, in different data servers or in totally different technologies - it does not matter. ODI 12c will derive and generate a plan that you can use or customize with knowledge modules. Some of the use cases which are greatly simplified include multiple heterogeneous targets, multi target inserts for Oracle and writing of XML. Let's switch it up now and look at a slightly different example to illustrate expression reuse. In ODI you can define reusable expressions using user functions. These can be reused across mappings and the implementations specialized per technology. So you can have common expressions across Oracle, SQL Server, Hive etc. shielding the design from the physical aspects of the generated language. Another way to reuse is within a mapping itself. In ODI 12c expressions can be defined and reused within a mapping. Rather than replicating the expression text in larger expressions you can decompose into smaller snippets, below you can see UNIT_TAX AMOUNT has been defined and is used in two downstream target columns - its used in the TOTAL_TAX_AMOUNT plus its used in the UNIT_TAX_AMOUNT (a recording of the calculation).  You can see the columns that the expressions depend on (upstream) and the columns the expression is used in (downstream) highlighted within the mapper. Also multi selecting attributes is a convenient way to see what's being used where, below I have selected the TOTAL_TAX_AMOUNT in the target datastore and the UNIT_TAX_AMOUNT in UNIT_CALC. You can now see many expressions at once now and understand much more at the once time without needlessly clicking around and memorizing information. Our mantra during development was to keep it simple and make the tool more powerful and do even more for the user. The development team was a fusion of many teams from Oracle Warehouse Builder, Sunopsis and BEA Aqualogic, debating and perfecting the mapper in ODI 12c. This was quite a project from supporting the capabilities of ODI in 11g to building the flow based mapping tool to support the future. I hope this was a useful insight, there is so much more to come on this topic, this is just a preview of much more that you will see of the mapper in ODI 12c.

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• .NET vs Windows 8

  - by Simon Cooper

  So, day 1 of DevWeek. Lots and lots of Windows 8 and WinRT, as you would expect. The keynote had some actual content in it, fleshed out some of the details of how your apps linked into the Metro infrastructure, and confirmed that there would indeed be an enterprise version of the app store available for Metro apps.) However, that's, not what I want to focus this post on. What I do want to focus on is this: Windows 8 does not make .NET developers obsolete. Phew! .NET in the New Ecosystem In all the hype around Windows 8 the past few months, a lot of developers have got the impression that .NET has been sidelined in Windows 8; C++ and COM is back in vogue, and HTML5 + JavaScript is the New Way of writing applications. You know .NET? It's yesterday's tech. Enter the 21st Century and write <div>! However, after speaking to people at the conference, and after a couple of talks by Dave Wheeler on the innards of WinRT and how .NET interacts with it, my views on the coming operating system have changed somewhat. To summarize what I've picked up, in no particular order (none of this is official, just my sense of what's been said by various people): Metro apps do not replace desktop apps. That is, Windows 8 fully supports .NET desktop applications written for every other previous version of Windows, and will continue to do so in the forseeable future. There are some apps that simply do not fit into Metro. They do not fit into the touch-based paradigm, and never will. Traditional desktop support is not going away anytime soon. The reason Silverlight has been hidden in all the Metro hype is that Metro is essentially based on Silverlight design principles. Silverlight developers will have a much easier time writing Metro apps than desktop developers, as they would already be used to all the principles of sandboxing and separation introduced with Silverlight. It's desktop developers who are going to have to adapt how they work. .NET + XAML is equal to HTML5 + JS in importance. Although the underlying WinRT system is built on C++ & COM, most application development will be done either using .NET or HTML5. Both systems have their own wrapper around the underlying WinRT infrastructure, hiding the implementation details. The CLR is unchanged; it's still the .NET 4 CLR, running IL in .NET assemblies. The thing that changes between desktop and Metro is the class libraries, which have more in common with the Silverlight libraries than the desktop libraries. In Metro, although all the types look and behave the same to callers, some of the core BCL types are now wrappers around their WinRT equivalents. These wrappers are then enhanced using standard .NET types and code to produce the Metro .NET class libraries. You can't simply port a desktop app into Metro. The underlying file IO, network, timing and database access is either completely different or simply missing. Similarly, although the UI is programmed using XAML, the behaviour of the Metro XAML is different to WPF or Silverlight XAML. Furthermore, the new design principles and touch-based interface for Metro applications demand a completely new UI. You will be able to re-use sections of your app encapsulating pure program logic, but everything else will need to be written from scratch. Microsoft has taken the opportunity to remove a whole raft of types and methods from the Metro framework that are obsolete (non-generic collections) or break the sandbox (synchronous APIs); if you use these, you will have to rewrite to use the alternatives, if they exist at all, to move your apps to Metro. If you want to write public WinRT components in .NET, there are some quite strict rules you have to adhere to. But the compilers know about these rules; you can write them in C# or VB, and the compilers will tell you when you do something that isn't allowed and deal with the translation to WinRT metadata rather than .NET assemblies. It is possible to write a class library that can be used in Metro and desktop applications. However, you need to be very careful not to use types that are available in one but not the other. One can imagine developers writing their own abstraction around file IO and UIs (MVVM anyone?) that can be implemented differently in Metro and desktop, but look the same within your shared library. So, if you're a .NET developer, you have a lot less to worry about. .NET is a viable platform on Metro, and traditional desktop apps are not going away. You don't have to learn HTML5 and JavaScript if you don't want to. Hurray!

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• JavaScript Class Patterns

  - by Liam McLennan

  To write object-oriented programs we need objects, and likely lots of them. JavaScript makes it easy to create objects: var liam = { name: "Liam", age: Number.MAX_VALUE }; But JavaScript does not provide an easy way to create similar objects. Most object-oriented languages include the idea of a class, which is a template for creating objects of the same type. From one class many similar objects can be instantiated. Many patterns have been proposed to address the absence of a class concept in JavaScript. This post will compare and contrast the most significant of them. Simple Constructor Functions Classes may be missing but JavaScript does support special constructor functions. By prefixing a call to a constructor function with the ‘new’ keyword we can tell the JavaScript runtime that we want the function to behave like a constructor and instantiate a new object containing the members defined by that function. Within a constructor function the ‘this’ keyword references the new object being created -  so a basic constructor function might be: function Person(name, age) { this.name = name; this.age = age; this.toString = function() { return this.name + " is " + age + " years old."; }; } var john = new Person("John Galt", 50); console.log(john.toString()); Note that by convention the name of a constructor function is always written in Pascal Case (the first letter of each word is capital). This is to distinguish between constructor functions and other functions. It is important that constructor functions be called with the ‘new’ keyword and that not constructor functions are not. There are two problems with the pattern constructor function pattern shown above: It makes inheritance difficult The toString() function is redefined for each new object created by the Person constructor. This is sub-optimal because the function should be shared between all of the instances of the Person type. Constructor Functions with a Prototype JavaScript functions have a special property called prototype. When an object is created by calling a JavaScript constructor all of the properties of the constructor’s prototype become available to the new object. In this way many Person objects can be created that can access the same prototype. An improved version of the above example can be written: function Person(name, age) { this.name = name; this.age = age; } Person.prototype = { toString: function() { return this.name + " is " + this.age + " years old."; } }; var john = new Person("John Galt", 50); console.log(john.toString()); In this version a single instance of the toString() function will now be shared between all Person objects. Private Members The short version is: there aren’t any. If a variable is defined, with the var keyword, within the constructor function then its scope is that function. Other functions defined within the constructor function will be able to access the private variable, but anything defined outside the constructor (such as functions on the prototype property) won’t have access to the private variable. Any variables defined on the constructor are automatically public. Some people solve this problem by prefixing properties with an underscore and then not calling those properties by convention. function Person(name, age) { this.name = name; this.age = age; } Person.prototype = { _getName: function() { return this.name; }, toString: function() { return this._getName() + " is " + this.age + " years old."; } }; var john = new Person("John Galt", 50); console.log(john.toString()); Note that the _getName() function is only private by convention – it is in fact a public function. Functional Object Construction Because of the weirdness involved in using constructor functions some JavaScript developers prefer to eschew them completely. They theorize that it is better to work with JavaScript’s functional nature than to try and force it to behave like a traditional class-oriented language. When using the functional approach objects are created by returning them from a factory function. An excellent side effect of this pattern is that variables defined with the factory function are accessible to the new object (due to closure) but are inaccessible from anywhere else. The Person example implemented using the functional object construction pattern is: var personFactory = function(name, age) { var privateVar = 7; return { toString: function() { return name + " is " + age * privateVar / privateVar + " years old."; } }; }; var john2 = personFactory("John Lennon", 40); console.log(john2.toString()); Note that the ‘new’ keyword is not used for this pattern, and that the toString() function has access to the name, age and privateVar variables because of closure. This pattern can be extended to provide inheritance and, unlike the constructor function pattern, it supports private variables. However, when working with JavaScript code bases you will find that the constructor function is more common – probably because it is a better approximation of mainstream class oriented languages like C# and Java. Inheritance Both of the above patterns can support inheritance but for now, favour composition over inheritance. Summary When JavaScript code exceeds simple browser automation object orientation can provide a powerful paradigm for controlling complexity. Both of the patterns presented in this article work – the choice is a matter of style. Only one question still remains; who is John Galt?

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• JavaScript Class Patterns

  - by Liam McLennan

  To write object-oriented programs we need objects, and likely lots of them. JavaScript makes it easy to create objects: var liam = { name: "Liam", age: Number.MAX_VALUE }; But JavaScript does not provide an easy way to create similar objects. Most object-oriented languages include the idea of a class, which is a template for creating objects of the same type. From one class many similar objects can be instantiated. Many patterns have been proposed to address the absence of a class concept in JavaScript. This post will compare and contrast the most significant of them. Simple Constructor Functions Classes may be missing but JavaScript does support special constructor functions. By prefixing a call to a constructor function with the ‘new’ keyword we can tell the JavaScript runtime that we want the function to behave like a constructor and instantiate a new object containing the members defined by that function. Within a constructor function the ‘this’ keyword references the new object being created -  so a basic constructor function might be: function Person(name, age) { this.name = name; this.age = age; this.toString = function() { return this.name + " is " + age + " years old."; }; } var john = new Person("John Galt", 50); console.log(john.toString()); Note that by convention the name of a constructor function is always written in Pascal Case (the first letter of each word is capital). This is to distinguish between constructor functions and other functions. It is important that constructor functions be called with the ‘new’ keyword and that not constructor functions are not. There are two problems with the pattern constructor function pattern shown above: It makes inheritance difficult The toString() function is redefined for each new object created by the Person constructor. This is sub-optimal because the function should be shared between all of the instances of the Person type. Constructor Functions with a Prototype JavaScript functions have a special property called prototype. When an object is created by calling a JavaScript constructor all of the properties of the constructor’s prototype become available to the new object. In this way many Person objects can be created that can access the same prototype. An improved version of the above example can be written: function Person(name, age) { this.name = name; this.age = age; } Person.prototype = { toString: function() { return this.name + " is " + this.age + " years old."; } }; var john = new Person("John Galt", 50); console.log(john.toString()); In this version a single instance of the toString() function will now be shared between all Person objects. Private Members The short version is: there aren’t any. If a variable is defined, with the var keyword, within the constructor function then its scope is that function. Other functions defined within the constructor function will be able to access the private variable, but anything defined outside the constructor (such as functions on the prototype property) won’t have access to the private variable. Any variables defined on the constructor are automatically public. Some people solve this problem by prefixing properties with an underscore and then not calling those properties by convention. function Person(name, age) { this.name = name; this.age = age; } Person.prototype = { _getName: function() { return this.name; }, toString: function() { return this._getName() + " is " + this.age + " years old."; } }; var john = new Person("John Galt", 50); console.log(john.toString()); Note that the _getName() function is only private by convention – it is in fact a public function. Functional Object Construction Because of the weirdness involved in using constructor functions some JavaScript developers prefer to eschew them completely. They theorize that it is better to work with JavaScript’s functional nature than to try and force it to behave like a traditional class-oriented language. When using the functional approach objects are created by returning them from a factory function. An excellent side effect of this pattern is that variables defined with the factory function are accessible to the new object (due to closure) but are inaccessible from anywhere else. The Person example implemented using the functional object construction pattern is: var john = new Person("John Galt", 50); console.log(john.toString()); var personFactory = function(name, age) { var privateVar = 7; return { toString: function() { return name + " is " + age * privateVar / privateVar + " years old."; } }; }; var john2 = personFactory("John Lennon", 40); console.log(john2.toString()); Note that the ‘new’ keyword is not used for this pattern, and that the toString() function has access to the name, age and privateVar variables because of closure. This pattern can be extended to provide inheritance and, unlike the constructor function pattern, it supports private variables. However, when working with JavaScript code bases you will find that the constructor function is more common – probably because it is a better approximation of mainstream class oriented languages like C# and Java. Inheritance Both of the above patterns can support inheritance but for now, favour composition over inheritance. Summary When JavaScript code exceeds simple browser automation object orientation can provide a powerful paradigm for controlling complexity. Both of the patterns presented in this article work – the choice is a matter of style. Only one question still remains; who is John Galt?

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• How to structure game states in an entity/component-based system

  - by Eva

  I'm making a game designed with the entity-component paradigm that uses systems to communicate between components as explained here. I've reached the point in my development that I need to add game states (such as paused, playing, level start, round start, game over, etc.), but I'm not sure how to do it with my framework. I've looked at this code example on game states which everyone seems to reference, but I don't think it fits with my framework. It seems to have each state handling its own drawing and updating. My framework has a SystemManager that handles all the updating using systems. For example, here's my RenderingSystem class: public class RenderingSystem extends GameSystem { private GameView gameView_; /** * Constructor * Creates a new RenderingSystem. * @param gameManager The game manager. Used to get the game components. */ public RenderingSystem(GameManager gameManager) { super(gameManager); } /** * Method: registerGameView * Registers gameView into the RenderingSystem. * @param gameView The game view registered. */ public void registerGameView(GameView gameView) { gameView_ = gameView; } /** * Method: triggerRender * Adds a repaint call to the event queue for the dirty rectangle. */ public void triggerRender() { Rectangle dirtyRect = new Rectangle(); for (GameObject object : getRenderableObjects()) { GraphicsComponent graphicsComponent = object.getComponent(GraphicsComponent.class); dirtyRect.add(graphicsComponent.getDirtyRect()); } gameView_.repaint(dirtyRect); } /** * Method: renderGameView * Renders the game objects onto the game view. * @param g The graphics object that draws the game objects. */ public void renderGameView(Graphics g) { for (GameObject object : getRenderableObjects()) { GraphicsComponent graphicsComponent = object.getComponent(GraphicsComponent.class); if (!graphicsComponent.isVisible()) continue; GraphicsComponent.Shape shape = graphicsComponent.getShape(); BoundsComponent boundsComponent = object.getComponent(BoundsComponent.class); Rectangle bounds = boundsComponent.getBounds(); g.setColor(graphicsComponent.getColor()); if (shape == GraphicsComponent.Shape.RECTANGULAR) { g.fill3DRect(bounds.x, bounds.y, bounds.width, bounds.height, true); } else if (shape == GraphicsComponent.Shape.CIRCULAR) { g.fillOval(bounds.x, bounds.y, bounds.width, bounds.height); } } } /** * Method: getRenderableObjects * @return The renderable game objects. */ private HashSet<GameObject> getRenderableObjects() { return gameManager.getGameObjectManager().getRelevantObjects( getClass()); } } Also all the updating in my game is event-driven. I don't have a loop like theirs that simply updates everything at the same time. I like my framework because it makes it easy to add new GameObjects, but doesn't have the problems some component-based designs encounter when communicating between components. I would hate to chuck it just to get pause to work. Is there a way I can add game states to my game without removing the entity-component design? Does the game state example actually fit my framework, and I'm just missing something? EDIT: I might not have explained my framework well enough. My components are just data. If I was coding in C++, they'd probably be structs. Here's an example of one: public class BoundsComponent implements GameComponent { /** * The position of the game object. */ private Point pos_; /** * The size of the game object. */ private Dimension size_; /** * Constructor * Creates a new BoundsComponent for a game object with initial position * initialPos and initial size initialSize. The position and size combine * to make up the bounds. * @param initialPos The initial position of the game object. * @param initialSize The initial size of the game object. */ public BoundsComponent(Point initialPos, Dimension initialSize) { pos_ = initialPos; size_ = initialSize; } /** * Method: getBounds * @return The bounds of the game object. */ public Rectangle getBounds() { return new Rectangle(pos_, size_); } /** * Method: setPos * Sets the position of the game object to newPos. * @param newPos The value to which the position of the game object is * set. */ public void setPos(Point newPos) { pos_ = newPos; } } My components do not communicate with each other. Systems handle inter-component communication. My systems also do not communicate with each other. They have separate functionality and can easily be kept separate. The MovementSystem doesn't need to know what the RenderingSystem is rendering to move the game objects correctly; it just need to set the right values on the components, so that when the RenderingSystem renders the game objects, it has accurate data. The game state could not be a system, because it needs to interact with the systems rather than the components. It's not setting data; it's determining which functions need to be called. A GameStateComponent wouldn't make sense because all the game objects share one game state. Components are what make up objects and each one is different for each different object. For example, the game objects cannot have the same bounds. They can have overlapping bounds, but if they share a BoundsComponent, they're really the same object. Hopefully, this explanation makes my framework less confusing.

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• Seizing the Moment with Mobility

  - by Divya Malik

  Empowering people to work where they want to work is becoming more critical now with the consumerisation of technology. Employees are bringing their own devices to the workplace and expecting to be productive wherever they are. Sales people welcome the ability to run their critical business applications where they can be most effective which is typically on the road and when they are still with the customer. Oracle has invested many years of research in understanding customer's Mobile requirements. “The keys to building the best user experience were building in a lot of flexibility in ways to support sales, and being useful,” said Arin Bhowmick, Director, CRM, for the Applications UX team. “We did that by talking to and analyzing the needs of a lot of people in different roles.” The team studied real-life sales teams. “We wanted to study salespeople in context with their work,” Bhowmick said. “We studied all user types in the CRM world because we wanted to build a user interface and user experience that would cater to sales representatives, marketing managers, sales managers, and more. Not only did we do studies in our labs, but also we did studies in the field and in mobile environments because salespeople are always on the go.” Here is a recent post from Hernan Capdevila, Vice President, Oracle Fusion Apps which was featured on the Oracle Applications Blog.  Mobile devices are forcing a paradigm shift in the workplace – they’re changing the way businesses can do business and the type of cultures they can nurture. As our customers talk about their mobile needs, we hear them saying they want instant-on access to enterprise data so workers can be more effective at their jobs anywhere, anytime. They also are interested in being more cost effective from an IT point of view. The mobile revolution – with the idea of BYOD (bring your own device) – has added an interesting dynamic because previously IT was driving the employee device strategy and ecosystem. That's been turned on its head with the consumerization of IT. Now employees are figuring out how to use their personal devices for work purposes and IT has to figure out how to adapt. Blurring the Lines between Work and Personal Life My vision of where businesses will be five years from now is that our work lives and personal lives will be more interwoven together. In turn, enterprises will have to determine how to make employees’ work lives fit more into the fabric of their personal lives. And personal devices like smartphones are going to drive significant business value because they let us accomplish things very incrementally. I can be sitting on a train or in a taxi and be productive. At the end of any meeting, I can capture ideas and tasks or follow up with people in real time. Mobile devices enable this notion of seizing the moment – capitalizing on opportunities that might otherwise have slipped away because we're not connected. For the industry shapers out there, this is game changing. The lean and agile workforce is definitely the future. This notion of the board sitting down with the executive team to lay out strategic objectives for a three- to five-year plan, bringing in HR to determine how they're going to staff the strategic activities, kicking off the execution, and then revisiting the plan in three to five years to create another three- to five-year plan is yesterday's model. Businesses that continue to approach innovating in that way are in the dinosaur age. Today it's about incremental planning and incremental execution, which requires a lot of cohesion and synthesis within the workforce. There needs to be this interweaving notion within the workforce about how ideas cascade down, how people engage, how they stay connected, and how insights are shared. How to Survive and Thrive in Today’s Marketplace The notion of Facebook isn’t new. We lived it pre-Internet days with America Online and Prodigy – Facebook is just the renaissance of these services in a more viral and pervasive way. And given the trajectory of the consumerization of IT with people bringing their personal tooling to work, the enterprise has no option but to adapt. The sooner that businesses realize this from a top-down point of view the sooner that they will be able to really drive significant innovation and adapt to the marketplace. There are a small number of companies right now (I think it's closer to 20% rather than 80%, but the number is expanding) that are able to really innovate in this incremental marketplace. So from a competitive point of view, there's no choice but to be social and stay connected. By far the majority of users on Facebook and LinkedIn are mobile users – people on iPhones, smartphones, Android phones, and tablets. It's not the couch people, right? It's the on-the-go people – those people at the coffee shops. Usually when you're sitting at your desk on a big desktop computer, typically you have better things to do than to be on Facebook. This is a topic I'm extremely passionate about because I think mobile devices are game changing. Mobility delivers significant value to businesses – it also brings dramatic simplification from a functional point of view and transforms our work life experience. Hernan Capdevila Vice President, Oracle Applications Development

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• C# Open Source software that is useful for learning Design Patterns

  - by Fathom Savvy

  In college I took a class in Expert Systems. The language the book taught (CLIPS) was esoteric - Expert Systems: Principles and Programming, Fourth Edition. I remember having a tough time with it. So, after almost failing the class, I needed to create the most awesome Expert System for my final presentation. I chose to create an expert system that would calculate risk analysis for a person's retirement portfolio. In short, the system would provide the services normally performed by one's financial adviser. In other words, based on personality, age, state of the macro economy, and other factors, should one's portfolio be conservative, moderate, or aggressive? In the appendix of the book (or on the CD-ROM), there was this in-depth example program for something unrelated to my presentation. Over my break, I read and re-read every line of that program until I understood it to the letter. Even though it was unrelated, I learned more than I ever could by reading all of the chapters. My presentation turned out to be pretty damn good and I received praises from my professor and classmates. So, the moral of the story is..., by understanding other people's code, you can gain greater insight into a language/paradigm than by reading canonical examples. Still, to this day, I am having trouble with everyday design patterns such as the Factory Pattern. I would like to know if anyone could recommend open source software that would help me understand the Gang of Four design patterns, at the very least. I have read the books, but I'm having trouble writing code for the concepts in the real world. Perhaps, by studying code used in today's real world applications, it might just "click". I realize a piece of software may only implement one kind of design pattern. But, if the pattern is an implementation you think is good for learning, and you know what pattern to look for within the source, I'm hoping you can tell me about it. For example, the System.Linq.Expressions namespace has a good example of the Visitor Pattern. The client calls Expression.Accept(new ExpressionVisitor()), which calls ExpressionVisitor (VisitExtension), which calls back to Expression (VisitChildren), which then calls Expression (Accept) again - wooah, kinda convoluted. The point to note here is that VisitChildren is a virtual method. Both Expression and those classes derived from Expression can implement the VisitChildren method any way they want. This means that one type of Expression can run code that is completely different from another type of derived Expression, even though the ExpressionVisitor class is the same in the Accept method. (As a side note Expression.Accept is also virtual). In the end, the code provides a real world example that you won't get in any book because it's kinda confusing. To summarize, If you know of any open source software that uses a design pattern implementation you were impressed by, please list it here. I'm sure it will help many others besides just me. public class VisitorPatternTest { public void Main() { Expression normalExpr = new Expression(); normalExpr.Accept(new ExpressionVisitor()); Expression binExpr = new BinaryExpression(); binExpr.Accept(new ExpressionVisitor()); } } public class Expression { protected internal virtual Expression Accept(ExpressionVisitor visitor) { return visitor.VisitExtension(this); } protected internal virtual Expression VisitChildren(ExpressionVisitor visitor) { if (!this.CanReduce) { throw Error.MustBeReducible(); } return visitor.Visit(this.ReduceAndCheck()); } public virtual Expression Visit(Expression node) { if (node != null) { return node.Accept(this); } return null; } public Expression ReduceAndCheck() { if (!this.CanReduce) { throw Error.MustBeReducible(); } Expression expression = this.Reduce(); if ((expression == null) || (expression == this)) { throw Error.MustReduceToDifferent(); } if (!TypeUtils.AreReferenceAssignable(this.Type, expression.Type)) { throw Error.ReducedNotCompatible(); } return expression; } } public class BinaryExpression : Expression { protected internal override Expression Accept(ExpressionVisitor visitor) { return visitor.VisitBinary(this); } protected internal override Expression VisitChildren(ExpressionVisitor visitor) { return CreateDummyExpression(); } protected internal Expression CreateDummyExpression() { Expression dummy = new Expression(); return dummy; } } public class ExpressionVisitor { public virtual Expression Visit(Expression node) { if (node != null) { return node.Accept(this); } return null; } protected internal virtual Expression VisitExtension(Expression node) { return node.VisitChildren(this); } protected internal virtual Expression VisitBinary(BinaryExpression node) { return ValidateBinary(node, node.Update(this.Visit(node.Left), this.VisitAndConvert<LambdaExpression>(node.Conversion, "VisitBinary"), this.Visit(node.Right))); } }

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• High Availability for IaaS, PaaS and SaaS in the Cloud

  - by BuckWoody

  Outages, natural disasters and unforeseen events have proved that even in a distributed architecture, you need to plan for High Availability (HA). In this entry I'll explain a few considerations for HA within Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS). In a separate post I'll talk more about Disaster Recovery (DR), since each paradigm has a different way to handle that. Planning for HA in IaaS IaaS involves Virtual Machines - so in effect, an HA strategy here takes on many of the same characteristics as it would on-premises. The primary difference is that the vendor controls the hardware, so you need to verify what they do for things like local redundancy and so on from the hardware perspective. As far as what you can control and plan for, the primary factors fall into three areas: multiple instances, geographical dispersion and task-switching. In almost every cloud vendor I've studied, to ensure your application will be protected by any level of HA, you need to have at least two of the Instances (VM's) running. This makes sense, but you might assume that the vendor just takes care of that for you - they don't. If a single VM goes down (for whatever reason) then the access to it is lost. Depending on multiple factors, you might be able to recover the data, but you should assume that you can't. You should keep a sync to another location (perhaps the vendor's storage system in another geographic datacenter or to a local location) to ensure you can continue to serve your clients. You'll also need to host the same VM's in another geographical location. Everything from a vendor outage to a network path problem could prevent your users from reaching the system, so you need to have multiple locations to handle this. This means that you'll have to figure out how to manage state between the geo's. If the system goes down in the middle of a transaction, you need to figure out what part of the process the system was in, and then re-create or transfer that state to the second set of systems. If you didn't write the software yourself, this is non-trivial. You'll also need a manual or automatic process to detect the failure and re-route the traffic to your secondary location. You could flip a DNS entry (if your application can tolerate that) or invoke another process to alias the first system to the second, such as load-balancing and so on. There are many options, but all of them involve coding the state into the application layer. If you've simply moved a state-ful application to VM's, you may not be able to easily implement an HA solution. Planning for HA in PaaS Implementing HA in PaaS is a bit simpler, since it's built on the concept of stateless applications deployment. Once again, you need at least two copies of each element in the solution (web roles, worker roles, etc.) to remain available in a single datacenter. Also, you need to deploy the application again in a separate geo, but the advantage here is that you could work out a "shared storage" model such that state is auto-balanced across the world. In fact, you don't have to maintain a "DR" site, the alternate location can be live and serving clients, and only take on extra load if the other site is not available. In Windows Azure, you can use the Traffic Manager service top route the requests as a type of auto balancer. Even with these benefits, I recommend a second backup of storage in another geographic location. Storage is inexpensive; and that second copy can be used for not only HA but DR. Planning for HA in SaaS In Software-as-a-Service (such as Office 365, or Hadoop in Windows Azure) You have far less control over the HA solution, although you still maintain the responsibility to ensure you have it. Since each SaaS is different, check with the vendor on the solution for HA - and make sure you understand what they do and what you are responsible for. They may have no HA for that solution, or pin it to a particular geo, or perhaps they have a massive HA built in with automatic load balancing (which is often the case).   All of these options (with the exception of SaaS) involve higher costs for the design. Do not sacrifice reliability for cost - that will always cost you more in the end. Build in the redundancy and HA at the very outset of the project - if you try to tack it on later in the process the business will push back and potentially not implement HA. References: http://www.bing.com/search?q=windows+azure+High+Availability  (each type of implementation is different, so I'm routing you to a search on the topic - look for the "Patterns and Practices" results for the area in Azure you're interested in)

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• Cloud Deployment Models

  - by B R Clouse

  Normal 0 false false false EN-US X-NONE X-NONE As the cloud paradigm grows in depth and breadth, more readers are approaching the topic for the first time, or from a new perspective.  This blog is a basic review of  cloud deployment models, to help orient newcomers and neophytes. Most cloud deployments today are either private or public. It is also possible to connect a private cloud and a public cloud to form a hybrid cloud. A private cloud is for the exclusive use of an organization. Enterprises, universities and government agencies throughout the world are using private clouds. Some have designed, built and now manage their private clouds. Others use a private cloud that was built by and is now managed by a provider, hosted either onsite or at the provider’s datacenter. Because private clouds are for exclusive use, they are usually the option chosen by organizations with concerns about data security and guaranteed performance. Public clouds are open to anyone with an Internet connection. Because they require no capital investment from their users, they are particularly attractive to companies with limited resources in less regulated environments and for temporary workloads such as development and test environments. Public clouds offer a range of products, from end-user software packages to more basic services such as databases or operating environments. Public clouds may also offer cloud services such as a disaster recovery for a private cloud, or the ability to “cloudburst” a temporary workload spike from a private cloud to a public cloud. These are examples of a hybrid cloud. These are most feasible when the private and public clouds are built with similar technologies. Usually people think of a public cloud in terms of a user role, e.g., “Which public cloud should I consider using?” But someone needs to own and manage that public cloud. The company who owns and operates a public cloud is known as a public cloud provider. Oracle Database Cloud Service, Amazon RDS, database.com and Savvis Symphony Database are examples of public cloud database services. Normal 0 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:0in; mso-para-margin-bottom:.0001pt; 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; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} When evaluating deployment models, be aware that you can use any or all of the available options. Some workloads may be best-suited for a private cloud, some for a public or hybrid cloud. And you might deploy multiple private clouds in your organization. If you are going to combine multiple clouds, then you want to make sure that each cloud is based on a consistent technology portfolio and architecture. This simplifies management and gives you the greatest flexibility in moving resources and workloads among your different clouds. Oracle’s portfolio of cloud products and services enables both deployment models. Oracle can manage either model. Universities, government agencies and companies in all types of business everywhere in the world are using clouds built with the Oracle portfolio. By employing a consistent portfolio, these customers are able to run all of their workloads – from test and development to the most mission-critical -- in a consistent manner: One Enterprise Cloud, powered by Oracle.   /* 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:0in; mso-para-margin-bottom:.0001pt; 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; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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• SVN naming convention: repository, branches, tags

  - by LookitsPuck

  Hey all! Just curious what your naming conventions are for the following: Repository name Branches Tags Right now, we're employing the following standards with SVN, but would like to improve on it: Each project has its own repository Each repository has a set of directories: tags, branches, trunk Tags are immutable copies of the the tree (release, beta, rc, etc.) Branches are typically feature branches Trunk is ongoing development (quick additions, bug fixes, etc.) Now, with that said, I'm curious how everyone is not only handling the naming of their repositories, but also their tags and branches. For example, do you employ a camel case structure for the project name? So, if your project is something like Backyard Baseball for Youngins, how do you handle that? backyardBaseballForYoungins backyard_baseball_for_youngins BackyardBaseballForYoungins backyardbaseballforyoungins That seems rather trivial, but it's a question. If you're going with the feature branch paradigm, how do you name your feature branches? After the feature itself in plain English? Some sort of versioning scheme? I.e. say you want to add functionality to the Backyard Baseball app that allows users to add their own statistics. What would you call your branch? {repoName}/branches/user-add-statistics {repoName}/branches/userAddStatistics {repoName}/branches/user_add_statistics etc. Or: {repoName}/branches/1.1.0.1 If you go the version route, how do you correlate the version numbers? It seems that feature branches wouldn't benefit much from a versioning schema, being that 1 developer could be working on the "user add statistics" functionality, and another developer could be working on the "admin add statistics" functionality. How are these do branch versions named? Are they better off being: {repoName}/branches/1.1.0.1 - user add statistics {repoName}/branches/1.1.0.2 - admin add statistics And once they're merged into the trunk, the trunk might increment appropriately? Tags seem like they'd benefit the most from version numbers. With that being said, how are you correlating the versions for your project (whether it be trunk, branch, tag, etc.) with SVN? I.e. how do you, as the developer, know that 1.1.1 has admin add statistics, and user add statistics functionality? How are these descriptive and linked? It'd make sense for tags to have release notes in each tag since they're immutable. But, yeah, what are your SVN policies going forward?

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• TVirtualStringTree - resetting non-visual nodes and memory consumption

  - by Remy Lebeau - TeamB

  I have an app that loads records from a binary log file and displays them in a virtual TListView. There are potentially millions of records in a file, and the display can be filtered by the user, so I do not load all of the records in memory at one time, and the ListView item indexes are not a 1-to-1 relation with the file record offsets (List item 1 may be file record 100, for instance). I use the ListView's OnDataHint event to load records for just the items the ListView is actually interested in. As the user scrolls around, the range specified by OnDataHint changes, allowing me to free records that are not in the new range, and allocate new records as needed. This works fine, speed is tolerable, and the memory footprint is very low. I am currently evaluating TVirtualStringTree as a replacement for the TListView, mainly because I want to add the ability to expand/collapse records that span multiple lines (I can fudge it with the TListView by incrementing/decrementing the item count dynamically, but this is not as straight forward as using a real tree). For the most part, I have been able to port the TListView logic and have everything work as I need. I notice that TVirtualStringTree's virtual paradigm is vastly different, though. It does not have the same kind of OnDataHint functionality that TListView does (I can use the OnScroll event to fake it, which allows my memory buffer logic to continue working), and I can use the OnInitializeNode event to associate nodes with records that are allocated. However, once a tree node is initialized, it sees that it remains initialized for the lifetime of the tree. That is not good for me. As the user scrolls around and I remove records from memory, I need to reset those non-visual nodes without removing them from the tree completely, or losing their expand/collapse states. When the user scrolls them back into view, I can re-allocate the records and re-initialize the nodes. Basically, I want to make TVirtualStringTree act as much like TListView as possible, as far as its virtualization is concerned. I have seen that TVirtualStringTree has a ResetNode() method, but I encounter various errors whenever I try to use it. I must be using it wrong. I also thought of just storing a data pointer inside each node to my record buffers, and I allocate and free memory, update those pointers accordingly. The end effect does not work so well, either. Worse, my largest test log file has ~5 million records in it. If I initialize the TVirtualStringTree with that many nodes at one time (when the log display is unfiltered), the tree's internal overhead for its nodes takes up a whopping 260MB of memory (without any records being allocated yet). Whereas with the TListView, loading the same log file and all the memory logic behind it, I can get away with using just a few MBs. Any ideas?

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• Best practices concerning view model and model updates with a subset of the fields

  - by Martin

  By picking MVC for developing our new site, I find myself in the midst of "best practices" being developed around me in apparent real time. Two weeks ago, NerdDinner was my guide but with the development of MVC 2, even it seems outdated. It's an thrilling experience and I feel privileged to be in close contact with intelligent programmers daily. Right now I've stumbled upon an issue I can't seem to get a straight answer on - from all the blogs anyway - and I'd like to get some insight from the community. It's about Editing (read: Edit action). The bulk of material out there, tutorials and blogs, deal with creating and view the model. So while this question may not spell out a question, I hope to get some discussion going, contributing to my decision about the path of development I'm to take. My model represents a user with several fields like name, address and email. All the names, in fact, on field each for first name, last name and middle name. The Details view displays all these fields but you can change only one set of fields at a time, for instance, your names. The user expands a form while the other fields are still visible above and below. So the form that is posted back contains a subset of the fields representing the model. While this is appealing to us and our layout concerns, for various reasons, it is to be shunned by serious MVC-developers. I've been reading about some patterns and best practices and it seems that this is not in key with the paradigm of viewmodel == view. Or have I got it wrong? Anyway, NerdDinner dictates using FormCollection och UpdateModel. All the null fields are happily ignored. Since then, the MVC-community has abandoned this approach to such a degree that a bug in MVC 2 was not discovered. UpdateModel does not work without a complete model in your formcollection. The view model pattern receiving most praise seems to be Dedicated view model that contains a custom view model entity and is the only one that my design issue could be made compatible with. It entails a tedious amount of mapping, albeit lightened by the use of AutoMapper and the ideas of Jimmy Bogard, that may or may not be worthwhile. He also proposes a 1:1 relationship between view and view model. In keeping with these design paradigms, I am to create a view and associated view for each of my expanding sets of fields. The view models would each be nearly identical, differing only in the fields which are read-only, the views also containing much repeated markup. This seems absurd to me. In future I may want to be able to display two, more or all sets of fields open simultaneously. I will most attentively read the discussion I hope to spark. Many thanks in advance.

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• Is the design notion of layers contrived?

  - by Bruce

  Hi all I'm reading through Eric Evans' awesome work, Domain-Driven Design. However, I can't help feeling that the 'layers' model is contrived. To expand on that statement, it seems as if it tries to shoe-horn various concepts into a specific, neat model, that of layers talking to each other. It seems to me that the layers model is too simplified to actually capture the way that (good) software works. To expand further: Evans says: "Partition a complex program into layers. Develop a design within each layer that is cohesive and that depends only on the layers below. Follow standard architectural patterns to provide loose coupling to the layers above." Maybe I'm misunderstanding what 'depends' means, but as far as I can see, it can either mean a) Class X (in the UI for example) has a reference to a concrete class Y (in the main application) or b) Class X has a reference to a class Y-ish object providing class Y-ish services (ie a reference held as an interface). If it means (a), then this is clearly a bad thing, since it defeats re-using the UI as a front-end to some other application that provides Y-ish functionality. But if it means (b), then how is the UI any more dependent on the application, than the application is dependent on the UI? Both are decoupled from each other as much as they can be while still talking to each other. Evans' layer model of dependencies going one way seems too neat. First, isn't it more accurate to say that each area of the design provides a module that is pretty much an island to itself, and that ideally all communication is through interfaces, in a contract-driven/responsibility-driven paradigm? (ie, the 'dependency only on lower layers' is contrived). Likewise with the domain layer talking to the database - the domain layer is as decoupled (through DAO etc) from the database as the database is from the domain layer. Neither is dependent on the other, both can be swapped out. Second, the idea of a conceptual straight line (as in from one layer to the next) is artificial - isn't there more a network of intercommunicating but separate modules, including external services, utility services and so on, branching off at different angles? Thanks all - hoping that your responses can clarify my understanding on this..

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• M-V-VM, isn't the Model leaking into the View?

  - by BFree

  The point of M-V-VM as we all know is about speraration of concerns. In patterns like MVVM, MVC or MVP, the main purpose is to decouple the View from the Data thereby building more flexible components. I'll demonstrate first a very common scenario found in many WPF apps, and then I'll make my point: Say we have some StockQuote application that streams a bunch of quotes and displays them on screen. Typically, you'd have this: StockQuote.cs : (Model) public class StockQuote { public string Symbol { get; set; } public double Price { get; set; } } StockQuoteViewModel.cs : (ViewModel) public class StockQuoteViewModel { private ObservableCollection<StockQuote> _quotes = new ObservableCollection<StockQuote>(); public ObservableCollection<StockQuote> Quotes { get { return _quotes; } } } StockQuoteView.xaml (View) <Window x:Class="WpfApplication1.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:WpfApplication1" Title="Window1" Height="300" Width="300"> <Window.DataContext> <local:StockQuoteViewModel/> </Window.DataContext> <Window.Resources> <DataTemplate x:Key="listBoxDateTemplate"> <StackPanel Orientation="Horizontal"> <TextBlock Text="{Binding Symbol}"/> <TextBlock Text="{Binding Price}"/> </StackPanel> </DataTemplate> </Window.Resources> <Grid> <ListBox ItemTemplate="{StaticResource listBoxDateTemplate}" ItemsSource="{Binding Quotes}"/> </Grid> </Window> And then you'd have some kind of service that would feed the ObservableCollection with new StockQuotes. My question is this: In this type of scenario, the StockQuote is considered the Model, and we're exposing that to the View through the ViewModel's ObservableCollection. Which basically means, our View has knowledge of the Model. Doesn't that violate the whole paradigm of M-V-VM? Or am I missing something here....?

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• Would someone mind giving suggestions for this new assembly language?

  - by Noctis Skytower

  Greetings! Last semester in college, my teacher in the Computer Languages class taught us the esoteric language named Whitespace. In the interest of learning the language better with a very busy schedule (midterms), I wrote an interpreter and assembler in Python. An assembly language was designed to facilitate writing programs easily, and a sample program was written with the given assembly mnemonics. Now that it is summer, a new project has begun with the objective being to rewrite the interpreter and assembler for Whitespace 0.3, with further developments coming afterwards. Since there is so much extra time than before to work on its design, you are presented here with an outline that provides a revised set of mnemonics for the assembly language. This post is marked as a wiki for their discussion. Have you ever had any experience with assembly languages in the past? Were there some instructions that you thought should have been renamed to something different? Did you find yourself thinking outside the box and with a different paradigm than in which the mnemonics were named? If you can answer yes to any of those questions, you are most welcome here. Subjective answers are appreciated! hold N Push the number onto the stack copy Duplicate the top item on the stack copy N Copy the nth item on the stack (given by the argument) onto the top of the stack swap Swap the top two items on the stack drop Discard the top item on the stack drop N Slide n items off the stack, keeping the top item add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo save Store load Retrieve L: Mark a location in the program call L Call a subroutine goto L Jump unconditionally to a label if=0 L Jump to a label if the top of the stack is zero if<0 L Jump to a label if the top of the stack is negative return End a subroutine and transfer control back to the caller exit End the program print chr Output the character at the top of the stack print int Output the number at the top of the stack input chr Read a character and place it in the location given by the top of the stack input int Read a number and place it in the location given by the top of the stack Question: How would you redesign, rewrite, or rename the previous mnemonics and for what reasons?

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• Web-Frameworks for Education Management Systems?

  - by Indebi

  So, I'm working on an idea and I'll go into a brief overview of that but my question is, What are some good web frameworks for this situation? I have some experience in the following languages: C# Python I have considerably more experience in C# than Python, however I am expecting to learn new things. My idea is this, a completely web-based community-oriented Education Management System that focuses on making students and teachers day-to-day lives easier. For students it will provide a centralized place for them to do homework, study for tests, and reinforce concepts learned previously in class. For teachers it will give them a centralized place to handle assignments, attendance, homework, tests, and all other major parts of classroom management. All of that, but in a community-oriented fashion. Everything a teacher does is shared and open to constructive criticism, allowing other teachers to use their assignments/tests and for students or other teachers to comment, rate and criticize their assignments. This encourages an environment of openness that will allow teacher's to focus on teaching and student's to focus on learning. And that community wouldn't be limited to one school or school-district, this system would be completely school-independent. Please note that I have no problem with hearing constructive criticism on this idea, however I would prefer if this post was more focused on my question. I have somewhat explored about the following options: Django ASP.NET Ruby on Rails Silverlight (1) I have Django installed and I played with it for a little bit, I really like how easy setting up databases are and how it handles the database completely for you. I don't really know how to use it very well and I don't quite understand the Model-View-Controller paradigm(?) for it yet but I haven't thought about it much. I also like the fact that it uses Python. (2) I don't really like Visual Studio for developing in ASP.NET, I hate the way the web-designer works and it just feels clunky and old. I like the server-side development part though. I don't like how expensive ASP.NET and overall Visual Studio is, even if I do get it for free for now using DreamSpark (3) I haven't been able to explore much with this, I could not get Rails (or maybe Ruby) properly installed. I first installed it within RadRails and that didn't work so I uninstalled RadRails and then installed the latest version of Ruby off the official Windows Installer and then installed Ruby on Rails through gem and even after all that it still didn't work, so I installed Netbeans and attempted to use it there but it still did not work (4) I like Silverlight in some extents, I've played with this one the most, it's very similar to WPF (which I've used the most) in a lot of ways but I don't like how database connectivity works, at least in comparison to Django. I also dislike how expensive everything with Microsoft is, even if I get it for free for now with DreamSpark. I would like to hear some suggestions from experienced web-developers as to what I should use and why, or at least what some good options are for my scenario Your help would be very appreciated

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• Why no switch on pointers?

  - by meeselet

  For instance: #include <stdio.h> void why_cant_we_switch_him(void *ptr) { switch (ptr) { case NULL: printf("NULL!\n"); break; default: printf("%p!\n", ptr); break; } } int main(void) { void *foo = "toast"; why_cant_we_switch_him(foo); return 0; } gcc test.c -o test test.c: In function 'why_cant_we_switch_him': test.c:5: error: switch quantity not an integer test.c:6: error: pointers are not permitted as case values Just curious. Is this a technical limitation? EDIT People seem to think there is only one constant pointer expression. Is that is really true, though? For instance, here is a common paradigm in Objective-C (it is really only C aside from NSString, id and nil, which are merely a pointers, so it is still relevant — I just wanted to point out that there is, in fact, a common use for it, despite this being only a technical question): #include <stdio.h> #include <Foundation/Foundation.h> static NSString * const kMyConstantObject = @"Foo"; void why_cant_we_switch_him(id ptr) { switch (ptr) { case kMyConstantObject: // (Note that we are comparing pointers, not string values.) printf("We found him!\n"); break; case nil: printf("He appears to be nil (or NULL, whichever you prefer).\n"); break; default: printf("%p!\n", ptr); break; } } int main(void) { NSString *foo = @"toast"; why_cant_we_switch_him(foo); foo = kMyConstantObject; why_cant_we_switch_him(foo); return 0; } gcc test.c -o test -framework Foundation test.c: In function 'why_cant_we_switch_him': test.c:5: error: switch quantity not an integer test.c:6: error: pointers are not permitted as case values It appears that the reason is that switch only allows integral values (as the compiler warning said). So I suppose a better question would be to ask why this is the case? (though it is probably too late now.)

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• How to learn proper C++?

  - by Chris

  While reading a long series of really, really interesting threads, I've come to a realization: I don't think I really know C++. I know C, I know classes, I know inheritance, I know templates (& the STL) and I know exceptions. Not C++. To clarify, I've been writing "C++" for more than 5 years now. I know C, and I know that C and C++ share a common subset. What I've begun to realize, though, is that more times than not, I wind up treating C++ something vaguely like "C with classes," although I do practice RAII. I've never used Boost, and have only read up on TR1 and C++0x - I haven't used any of these features in practice. I don't use namespaces. I see a list of #defines, and I think - "Gracious, that's horrible! Very un-C++-like," only to go and mindlessly write class wrappers for the sake of it, and I wind up with large numbers (maybe a few per class) of static methods, and for some reason, that just doesn't seem right lately. The professional in me yells "just get the job done," the academic yells "you should write proper C++ when writing C++" and I feel like the point of balance is somewhere in between. I'd like to note that I don't want to program "pure" C++ just for the sake of it. I know several languages. I have a good feel for what "Pythonic" is. I know what clean and clear PHP is. Good C code I can read and write better than English. The issue is that I learned C by example, and picked up C++ as a "series of modifications" to C. And a lot of my early C++ work was creating class wrappers for C libraries. I feel like my own personal C-heavy background while learning C++ has sort of... clouded my acceptance of C++ in it's own right, as it's own language. Do the weathered C++ lags here have any advice for me? Good examples of clean, sharp C++ to learn from? What habits of C does my inner-C++ really need to break from? My goal here is not to go forth and trumpet "good" C++ paradigm from rooftops for the sake of it. C and C++ are two different languages, and I want to start treating them that way. How? Where to start? Thanks in advance! Cheers, -Chris

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• Casting objects in C# (ASP.Net MVC)

  - by Mortanis

  I'm coming from a background in ColdFusion, and finally moving onto something modern, so please bear with me. I'm running into a problem casting objects. I have two database tables that I'm using as Models - Residential and Commercial. Both of them share the majority of their fields, though each has a few unique fields. I've created another class as a container that contains the sum of all property fields. Query the Residential and Commercial, stuff it into my container, cunningly called Property. This works fine. However, I'm having problems aliasing the fields from Residential/Commercial onto Property. It's quite easy to create a method for each property: fillPropertyByResidential(Residential source) and fillPropertyByCommercial(Commercial source), and alias the variables. That also works fine, but quite obviously will copy a bunch of code - all those fields that are shared between the two main Models. So, I'd like a generic fillPropertyBySource() that takes the object, and detects if it's Residential or Commercial, fills the particular fields of each respective type, then do all the fields in common. Except, I gather in C# that variables created inside an If are only in the scope of the if, so I'm not sure how to do this. public property fillPropertyBySource(object source) { property prop = new property(); if (source is Residential) { Residential o = (Residential)source; //Fill Residential only fields } else if (source is Commercial) { Commercial o = (Commercial)source; //Fill Commercial only fields } //Fill fields shared by both prop.price = (int)o.price; prop.bathrooms = (float)o.bathrooms; return prop; } "o" being a Commercial or Residential only exists within the scope of the if. How do I detect the original type of the source object and take action? Bear with me - the shift from ColdFusion into a modern language is pretty..... difficult. More so since I'm used to procedural code and MVC is a massive paradigm shift. Edit: I should include the error: The name 'o' does not exist in the current context For the aliases of price and bathrooms in the shared area.

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• How can I represent a line of music notes in a way that allows fast insertion at any index?

  - by chairbender

  For "fun", and to learn functional programming, I'm developing a program in Clojure that does algorithmic composition using ideas from this theory of music called "Westergaardian Theory". It generates lines of music (where a line is just a single staff consisting of a sequence of notes, each with pitches and durations). It basically works like this: Start with a line consisting of three notes (the specifics of how these are chosen are not important). Randomly perform one of several "operations" on this line. The operation picks randomly from all pairs of adjacent notes that meet a certain criteria (for each pair, the criteria only depends on the pair and is independent of the other notes in the line). It inserts 1 or several notes (depending on the operation) between the chosen pair. Each operation has its own unique criteria. Continue randomly performing these operations on the line until the line is the desired length. The issue I've run into is that my implementation of this is quite slow, and I suspect it could be made faster. I'm new to Clojure and functional programming in general (though I'm experienced with OO), so I'm hoping someone with more experience can point out if I'm not thinking in a functional paradigm or missing out on some FP technique. My current implementation is that each line is a vector containing maps. Each map has a :note and a :dur. :note's value is a keyword representing a musical note like :A4 or :C#3. :dur's value is a fraction, representing the duration of the note (1 is a whole note, 1/4 is a quarter note, etc...). So, for example, a line representing the C major scale starting on C3 would look like this: [ {:note :C3 :dur 1} {:note :D3 :dur 1} {:note :E3 :dur 1} {:note :F3 :dur 1} {:note :G3 :dur 1} {:note :A4 :dur 1} {:note :B4 :dur 1} ] This is a problematic representation because there's not really a quick way to insert into an arbitrary index of a vector. But insertion is the most frequently performed operation on these lines. My current terrible function for inserting notes into a line basically splits the vector using subvec at the point of insertion, uses conj to join the first part + notes + last part, then uses flatten and vec to make them all be in a one-dimensional vector. For example if I want to insert C3 and D3 into the the C major scale at index 3 (where the F3 is), it would do this (I'll use the note name in place of the :note and :dur maps): (conj [C3 D3 E3] [C3 D3] [F3 G3 A4 B4]), which creates [C3 D3 E3 [C3 D3] [F3 G3 A4 B4]] (vec (flatten previous-vector)) which gives [C3 D3 E3 C3 D3 F3 G3 A4 B4] The run time of that is O(n), AFAIK. I'm looking for a way to make this insertion faster. I've searched for information on Clojure data structures that have fast insertion but haven't found anything that would work. I found "finger trees" but they only allow fast insertion at the start or end of the list. Edit: I split this into two questions. The other part is here.

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• Recommendations for distributed processing/distributed storage systems

  - by Eddie

  At my organization we have a processing and storage system spread across two dozen linux machines that handles over a petabyte of data. The system right now is very ad-hoc; processing automation and data management is handled by a collection of large perl programs on independent machines. I am looking at distributed processing and storage systems to make it easier to maintain, evenly distribute load and data with replication, and grow in disk space and compute power. The system needs to be able to handle millions of files, varying in size between 50 megabytes to 50 gigabytes. Once created, the files will not be appended to, only replaced completely if need be. The files need to be accessible via HTTP for customer download. Right now, processing is automated by perl scripts (that I have complete control over) which call a series of other programs (that I don't have control over because they are closed source) that essentially transforms one data set into another. No data mining happening here. Here is a quick list of things I am looking for: Reliability: These data must be accessible over HTTP about 99% of the time so I need something that does data replication across the cluster. Scalability: I want to be able to add more processing power and storage easily and rebalance the data on across the cluster. Distributed processing: Easy and automatic job scheduling and load balancing that fits with processing workflow I briefly described above. Data location awareness: Not strictly required but desirable. Since data and processing will be on the same set of nodes I would like the job scheduler to schedule jobs on or close to the node that the data is actually on to cut down on network traffic. Here is what I've looked at so far: Storage Management: GlusterFS: Looks really nice and easy to use but doesn't seem to have a way to figure out what node(s) a file actually resides on to supply as a hint to the job scheduler. GPFS: Seems like the gold standard of clustered filesystems. Meets most of my requirements except, like glusterfs, data location awareness. Ceph: Seems way to immature right now. Distributed processing: Sun Grid Engine: I have a lot of experience with this and it's relatively easy to use (once it is configured properly that is). But Oracle got its icy grip around it and it no longer seems very desirable. Both: Hadoop/HDFS: At first glance it looked like hadoop was perfect for my situation. Distributed storage and job scheduling and it was the only thing I found that would give me the data location awareness that I wanted. But I don't like the namename being a single point of failure. Also, I'm not really sure if the MapReduce paradigm fits the type of processing workflow that I have. It seems like you need to write all your software specifically for MapReduce instead of just using Hadoop as a generic job scheduler. OpenStack: I've done some reading on this but I'm having trouble deciding if it fits well with my problem or not. Does anyone have opinions or recommendations for technologies that would fit my problem well? Any suggestions or advise would be greatly appreciated. Thanks!

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• Interesting things – Twitter annotations and your phone as a web server

  - by jamiet

  I overheard/read a couple of things today that really made me, data junkie that I am, take a step back and think, “Hmmm, yeah, that could be really interesting” and I wanted to make a note of them here so that (a) I could bring them to the attention of anyone that happens to read this and (b) I can maybe come back here in a few years and see if either of these have come to fruition. Your phone as a web server While listening to Jon Udell’s (twitter) “Interviews with Innovators Podcast” today in which he interviewed Herbert Van de Sompel (twitter) about his Momento project. During the interview Jon and Herbert made the following remarks: Jon: [some people] really had this vision of a web of servers, the notion that every node on the internet, every connected entity, is potentially a server and a client…we can see where we’re getting to a point where these endpoint devices we have in our pockets are going to be massively capable and it may be in the not too distant future that significant chunks of the web archive will be cached all over the place including on your own machine… Herbert: wasn’t it Opera who at one point turned your browser into a server? That really got my brain ticking. We all carry a mobile phone with us and therefore we all potentially carry a mobile web server with us as well and to my mind the only thing really stopping that from happening is the capabilities of the phone hardware, the capabilities of the network infrastructure and the will to just bloody do it. Certainly all the standards required for addressing a web server on a phone already exist (to this uninitiated observer DNS and IPv6 seem to solve that problem) so why not? I tweeted about the idea and Rory Street answered back with “why would you want a phone to be a web server?”: Its a fair question and one that I would like to try and answer. Mobile phones are increasingly becoming our window onto the world as we use them to upload messages to Twitter, record our location on FourSquare or interact with our friends on Facebook but in each of these cases some other service is acting as our intermediary; to see what I’m thinking you have to go via Twitter, to see where I am you have to go to FourSquare (I’m using ‘I’ liberally, I don’t actually use FourSquare before you ask). Why should this have to be the case? Why can’t that data be decentralised? Why can’t we be masters of our own data universe? If my phone acted as a web server then I could expose all of that information without needing those intermediary services. I see a time when we can pass around URLs such as the following: http://jamiesphone.net/location/current - Where is Jamie right now? http://jamiesphone.net/location/2010-04-21 – Where was Jamie on 21st April 2010? http://jamiesphone.net/thoughts/current – What’s on Jamie’s mind right now? http://jamiesphone.net/blog – What documents is Jamie sharing with me? http://jamiesphone.net/calendar/next7days – Where is Jamie planning to be over the next 7 days? and those URLs get served off of the phone in our pockets. If we govern that data then we can control who has access to it and (crucially) how long its available for. Want to wipe yourself off the face of the web? its pretty easy if you’re in control of all the data – just turn your phone off. None of this exists today but I look forward to a time when it does. Opera really were onto something last June when they announced Opera Unite (admittedly Unite only works because Opera provide an intermediary DNS-alike system – it isn’t totally decentralised). Opening up Twitter annotations Last week Twitter held their first developer conference called Chirp where they announced an upcoming new feature called ‘Twitter Annotations’; in short this will allow us to attach metadata to a Tweet thus enhancing the tweet itself. Think of it as a richer version of hashtags. To think of it another way Twitter are turning their data into a humongous Entity-Attribute-Value or triple-tuple store. That alone has huge implications both for the web and Twitter as a whole – the ability to enrich that 140 characters data and thus make it more useful is indeed compelling however today I stumbled upon a blog post from Eugene Mandel entitled Tweet Annotations – a Way to a Metadata Marketplace? where he proposed the idea of allowing tweets to have metadata added by people other than the person who tweeted the original tweet. This idea really fascinated me especially when I read some of the potential uses that Eugene and his commenters suggested. They included: Amazon could attach an ISBN to a tweet that mentions a book. Specialist clients apps for book lovers could be built up around this metadata. Advertisers could pay to place adverts in metadata. The revenue generated from those adverts could be shared with the tweeter or people who add the metadata. Granted, allowing anyone to add metadata to a tweet has the potential to create a spam problem the like of which we haven’t even envisaged but spam hasn’t halted the growth of the web and neither should it halt the growth of data annotations either. The original tweeter should of course be able to determine who can add metadata and whether it should be moderated. As Eugene says himself: Opening publishing tweet annotations to anyone will open the way to a marketplace of metadata where client developers, data mining companies and advertisers can add new meaning to Twitter and build innovative businesses. What Eugene and his followers did not mention is what I think is potentially the most fascinating use of opening up annotations. Google’s success today is built on their page rank algorithm that measures the validity of a web page by the number of incoming links to it and the page rank of the sites containing those links – its a system built on reputation. Twitter annotations could open up a new paradigm however – let’s call it People rank- where reputation can be measured by the metadata that people choose to apply to links and the websites containing those links. Its not hard to see why Google and Microsoft have paid big bucks to get access to the Twitter firehose! Neither of these features, phones as a web server or the ability to add annotations to other people’s tweets, exist today but I strongly believe that they could dramatically enhance the web as we know it today. I hope to look back on this blog post in a few years in the knowledge that these ideas have been put into place. @Jamiet Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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