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• Amazon AMIs and Oracle VM templates

  - by llaszews

  I have worked with Oracle VM templates and most recently with Amazon Machine Images (AMI). The similarities in the functionality and capabilities they provide are striking. Just take a look a the definitions: An Amazon Machine Image (AMI) is a special type of pre-configured operating system and virtual application software which is used to create a virtual machine within the Amazon Elastic Compute Cloud (EC2). It serves as the basic unit of deployment for services delivered using EC2. AWS AMIs Oracle VM Templates provide an innovative approach to deploying a fully configured software stack by offering pre-installed and pre-configured software images. Use of Oracle VM Templates eliminates the installation and configuration costs, and reduces the ongoing maintenance costs helping organizations achieve faster time to market and lower cost of operations. Oracle VM Templates Other things they have in common: 1. Both have 35 Oracle images or templates: AWS AMI pre-built images Oracle pre-built VM Templates 2. Both allow to build your own images or templates: A. OVM template builder - OVM Template Builder - Oracle VM Template Builder, an open source, graphical utility that makes it easy to use Oracle Enterprise Linux “Just enough OS” (JeOS)–based scripts for developing pre-packaged virtual machines for Oracle VM. B. AMI 'builder' - AMI builder However, AWS has the added feature/benefit of adding your own AMI to the AWS AMI catalog: AMI - Adding to the AWS AMI catalog Another plus with AWS and AMI is there are hundreds of MySQL AMIs (AWS MySQL AMIs ). A benefit of Oracle VM templates is they can run on any public or private cloud environment, not just AWS EC2. However, with Oracle VM templates they first need to be images as AMIs before they can run in the AWS cloud.

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• Library Organization in .NET

  - by Greg Ros

  I've written a .NET bitwise operations library as part of my projects (stuff ranging from get MSB set to some more complicated bitwise transformations) and I mean to release it as free software. I'm a bit confused about a design aspect of the library, though. Many of the methods/transformations in the library come with different endianness. A simple example is a getBitAt method that regards index 0 as the least significant bit, or the most significant bit, depending on the version used. In practice, I've found that using separate functions for different endianness results in much more comprehensible and reusable code than assuming all operations are little-endian or something. I'm really stumped regarding how best to package the library. Should I have methods that have LE and BE versions take an enum parameter in their signature, e.g. Endianness.Little, Endianness.Big? Should I have different static classes with identically named methods? such as MSB.GetBit and LSB.GetBit On a much wider note, is there a standard I could use in cases like this? Some guide? Is my design issue trivial? I have a perfectionist bent, and I sometimes get stuck on tricky design issues like this... Note: I've sort of realized I'm using endianness somewhat colloquially to refer to the order/place value of digital component parts (be they bits, bytes, or words) in a larger whole, in any setting. I'm not talking about machine-level endianness or serial transmission endianness. Just about place-value semantics in general. So there isn't a context of targeting different machines/transmission techniques or something.

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• Ditch cPanel / WHM in favour of manual seup

  - by BWRic

  We currently use cPanel / WHM on a reseller account but are looking at getting a dedicated server. My first thought was to duplicate this set up on the dedicated box to allow us to quickly create new accounts. I'll be a managed server so they'll have set up the LAMP stack. I'm curious if I actually need cPanel and WHM. We don't use many of the features from cPanel / WHM, just creating accounts and databases, clients do not have FTP access. I'm no sys admin and come from a Windows / GUI background but have some knowledge in setting up development servers. WHM: Creating accounts I presume this sets up the Apache virtual host, FTP access and DNS settings. I've some knowledge of editing the Apache files to create virtual hosts. Am I correct in thinking as long as the DNS is pointing to the server IP and the virtual host is configured the server can serve the (php) pages? I'm not sure I need per site FTP access as only we will have access so I could have a server wide/htdocs only access to view all the site. The company who supply the dedicated hosts would also provide the own DNS management tool so I'm not need to cPanel one. MySQL: Creating users and databases We use cPanel to create the MySQL users and databases. As it's a dedicated box and I can have root access I think this could be replaced by SQLyog for db management and phpMyAdmin for user management. Do you I need cPanel or can I get by editing a few text files for creating the accounts, then use the MySQL tools for databases? Or am I missing something major with how the sites are configured?

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• SSMS Tools Pack 2.5.3 is out with bug fixes and improved licensing

  - by Mladen Prajdic

  Licensing for SSMS Tools Pack 2.5 has been quite a hit and I received some awesome feedback. The version 2.5.3 contains a few bug fixes and desired licensing improvements. Changes include more licensing options, prices in Euros because of book keeping reasons (don't you just love those :)) and generally easier purchase and licensing process for users. Licensing now offers four options: Per machine license. (€25) Perfect if you do all your work from a single machine. Plus one OS reinstall activation. Personal license (€75) Up to 4 machine activations. Plus 2 OS reinstall activations and any number of virtual machine activations. Team license (€240) Up to 10 machine activations. Plus 4 OS reinstall activations and any number of virtual machine activations. Enterprise license (€350+) For more than 10 machine activations any number of virtual machine activations. 30 days license. Time based demo license bound to a machine. You can view all the details on the Licensing page . If you want to receive email notifications when new version of SSMS Tools Pack is out you can do that on the Main page or on the Download page . Version 2.7 is expected in the first half of February and won't support SSMS 2005 and 2005 Express anymore. Enjoy it!

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• Best of OTN - Week of November 4th

  - by CassandraClark-OTN

  It was another exciting week at OTN!  Lots of GREAT content to share.  If you had a favorite that you don't see listed let us know in the comment section below.  Java Community - JavaOne Sessions Online - We've posted 60 of the JavaOne sessions online, and we'll be rolling out more sessions every few weeks. This content is free, courtesy of Oracle.NetBeans 7.4 Released  - NetBeans 7.4 features HTML5 integration for Java EE and PHP development; support for Apache Cordova and JDK 8 preview features; enhancements to Maven, C/C++, and more.vJUG: Worldwide Virtual JUG Created - London Java Community leader and technical evangelist Simon Maple has created a Meetup called vJUG, with aim toward connecting Java Developers in the virtual world.Tori Wieldt, Java Community Manager Friday Funny: This is what REALLY happens when you give someone your business card ow.ly/q6aKUArchitect Community - Don't forget to register for the free Virtual Developer Day - Harnessing the Power of Oracle WebLogic and Oracle Coherence.  December 3rd, 2013 - Two great tracks, Design & Develop and Build, Deploy & Manage.   Why wait, register now!  Multi-Factor Authentication in Oracle WebLogic - Shailesh K. Mishra - Really good technical article on using multi-factor authentication to protect web applications deployed on Oracle WebLogic.Coherence*Web: Sharing an httpSessions Among Applications in Different Oracle WebLogic Clusters - Jordi VillenaUnderstanding when and how to select session attributes that must be stored in the local storage of the Oracle WebLogic instances and which should be leveraged to an Oracle Coherence distributed cache.  Bob Rhubart, Architect Community Manager Friday Funny - "Be yourself, everyone else is already taken." Oscar Wilde (October 16, 1854 - November 30, 1900) Irish writer and poet.

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• Augmenting functionality of subclasses without code duplication in C++

  - by Rob W

  I have to add common functionality to some classes that share the same superclass, preferably without bloating the superclass. The simplified inheritance chain looks like this: Element -> HTMLElement -> HTMLAnchorElement Element -> SVGElement -> SVGAlement The default doSomething() method on Element is no-op by default, but there are some subclasses that need an actual implementation that requires some extra overridden methods and instance members. I cannot put a full implementation of doSomething() in Element because 1) it is only relevant for some of the subclasses, 2) its implementation has a performance impact and 3) it depends on a method that could be overridden by a class in the inheritance chain between the superclass and a subclass, e.g. SVGElement in my example. Especially because of the third point, I wanted to solve the problem using a template class, as follows (it is a kind of decorator for classes): struct Element { virtual void doSomething() {} }; // T should be an instance of Element template<class T> struct AugmentedElement : public T { // doSomething is expensive and uses T virtual void doSomething() override {} // Used by doSomething virtual bool shouldDoSomething() = 0; }; class SVGElement : public Element { /* ... */ }; class SVGAElement : public AugmentedElement<SVGElement> { // some non-trivial check bool shouldDoSomething() { /* ... */ return true; } }; // Similarly for HTMLAElement and others I looked around (in the existing (huge) codebase and on the internet), but didn't find any similar code snippets, let alone an evaluation of the effectiveness and pitfalls of this approach. Is my design the right way to go, or is there a better way to add common functionality to some subclasses of a given superclass?

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• Interview Questions in OOP

  - by Fero

  Hi all, I faced the below interview questions in OOP under PHP language. Kindly clear my clarifications regarding this. I am very confused. As i am a beginner to OOP i got too confused. Could anyone clarify these things clearly? Difference between Abstract class and interface. Interviewer : Let us consider abstract class contains three abstract methods such as a,b,c and interface contains three methods a,b,c. In this case these do the same functionality. Then why are going for abstract and why are we going for interface. Me : ? static keyword. Interviewer: We call static method without creating object by using scope resolution operator in PHP. As well as we can able to call concrete methods also. Then what is need of static keyword there? Me : .... final keyword. Interviewer: Give me any scenario of using final keyword. Me : For db connection related method Interviewer: Other than that? Me: ... Constructor. Interviewer: What is the use of constructor? Me : There is no need for object to access this. It will call automatically when the class calls. Interviewer: Other than that? Me : .... Thanks in advance...

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• How to make and restore incremental snapshots of hard disk

  - by brunopereira81

  I use Virtual Box a lot for distro / applications testing purposes. One of the features I simply love about it is virtual machines snapshots, its saves a state of a virtual machine and is able to restore it to its former glory if something you did went wrong without any problems and without consuming your all hard disk space. On my live systems I know how to create a 1:1 image of the file system but all the solutions I'v known will create a new image of the complete file system. Are there any programs / file systems that are capable of taking a snapshot of a current file system, save it on another location but instead of making a complete new image it creates incremental backups? To easy describe what I want, it should be as dd images of a file system, but instead of only a full backup it would also create incremental. I am not looking for clonezilla, etc. It should run within the system itself with no (or almost none) intervention from the user, but contain all the data of the file systems. I am also not looking for a duplicity backup your all system excluding some folders script + dd to save your mbr. I can do that myself, looking for extra finesse. I'm looking for something I can do before doing massive changes to a system and then if something when wrong or I burned my hard disk after spilling coffee on it I can just boot from a liveCD and restore a working snapshot to a hard disk. It does not need to be daily, it doesn't even need a schedule. Just run once in a while and let it its job and preferably RAW based not file copy based.

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• Would it be possible to create an open source software library, entirely developed and moderated by an open community?

  - by Steven Jeuris

  Call it democratic software development, or open source on steroids if you will. I'm not just talking about the possibility of providing a patch which can be approved by the library owner. Think more along the lines of how Stack Exchange works. Anyone can post code, and through community moderation it is cleaned up and eventually valid code ends up in the final library. For complex libraries an elaborate system should probably be created, but for a simple library it is my belief this is already possible even within the Stack Exchange platform. Take a library of extension methods for .NET for example. Everybody goes their own way and implements their own subset of what they feel is important, open-source library or not. People want to share their code, but there is no suitable platform for it. extensionmethod.net is the result of answering this call for extension methods, but the framework hopelessly falls short; there is no order, or structure at all. You don't know whether an idea is any good until you try it, so I decided to create an Extension Methods proposal on Area51. I belief with proper moderation, it could be possible for the site to be more than a Q&A site, and that an actual library (or subsets of it) could be extracted from it. Has anything like this been attempted before? Are there platforms better suited for this?

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• How to document requirements for an API systematically?

  - by Heinrich

  I am currently working on a project, where I have to analyze the requirements of two given IT systems, that use cloud computing, for a Cloud API. In other words, I have to analyze what requirements these systems have for a Cloud API, such that they would be able to switch it, while being able to accomplish their current goals. Let me give you an example for some informal requirements of Project A: When starting virtual machines in the cloud through the API, it must be possible to specify the memory size, CPU type, operating system and a SSH key for the root user. It must be possible to monitor the inbound and outbound network traffic per hour per virtual machine. The API must support the assignment of public IPs to a virtual machine and the retrieval of the public IPs. ... In a later stage of the project I will analyze some Cloud Computing standards that standardize cloud APIs to find out where possible shortcomings in the current standards are. A finding could and will probably be, that a certain standard does not support monitoring resource usage and thus is not currently usable. I am currently trying to find a way to systematically write down and classify my requirements. I feel that the way I currently have them written down (like the three points above) is too informal. I have read in a couple of requirements enineering and software architecture books, but they all focus too much on details and implementation. I do really only care about the functionalities provided through the API/interface and I don't think UML diagrams etc. are the right choice for me. I think currently the requirements that I collected can be described as user stories, but is that already enough for a sophisticated requirements analysis? Probably I should go "one level deeper" ... Any advice/learning resources for me?

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• Happy Day! VS2010 SP1, Project Server Integration, Load Test Feature Pack

  - by Aaron Kowall

  Microsoft released a PILE of Visual Studio goodness today: Visual Studio 2010 SP1(Including TFS SP1) Finally done with remembering which GDR packs, KB Patches, etc need to be installed with a new VS/TFS 2010 deployment.  Just grab the SP1.  It’s available today for MSDN Subscribers and March 10th for public download. TFS-Project Server Integration Feature Pack MSDN Subscribers got another little treat today with the TFS-Project Server integration feature pack.  We can now get project rollups and portfolio level management with Project Server yet still have the tight developer interaction with TFS.  Finally we can make the PMO happy without duplicate entry or MS Project gymnastics. Visual Studio Load Test Feature Pack This is a new benefit for Visual Studio 2010 Ultimate subscribers.  Previously there was a limit to Ultimate Load Testing of 250 virtual users. If you needed more, you had to buy virtual user license packs.  No more.  Now your Visual Studio Ultimate license allows you to simulate as many virtual users as you need!!  This is HUGE in improving adoption of regular load testing for development projects. All the Details are available from Soma’s blog. Technorati Tags: VS2010,TFS,Load Test

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• Java's Object.wait method with nanoseconds: Is this a joke or am I missing something

  - by Krumia

  I was checking out the Java API source code (Java 8) just out of curiosity. And I found this in java/lang/Object.java. There are three methods named wait: public final native void wait(long timeout): This is the core of all wait methods, which has a native implementation. public final void wait(): Just calls wait(0). And then there is public final void wait(long timeout, int nanos). The JavaDoc for the particular method tells me that, This method is similar to the wait method of one argument, but it allows finer control over the amount of time to wait for a notification before giving up. The amount of real time, measured in nanoseconds, is given by: 1000000*timeout+nanos But this is how the methods achieves "finer control over the amount of time to wait": if (nanos >= 500000 || (nanos != 0 && timeout == 0)) { timeout++; } wait(timeout); So this method basically does a crude rounding up of nanoseconds to milliseconds. Not to mention that anything below 500000ns/0.5ms will be ignored. Is this piece of code bad/unnecessary code, or am I missing some unseen virtue of declaring this method, and it's no argument cousin as the way they are?

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• Exalogic Elastic Cloud Software (EECS) version 2.0.1 available

  - by JuergenKress

  We are pleased to announce that as of today (May 14, 2012) the Exalogic Elastic Cloud Software (EECS) version 2.0.1 has been made Generally Available. This release is the culmination of over two and a half years of engineering effort from an extended team spanning 18 product development organizations on three continents, and is the most powerful, sophisticated and comprehensive Exalogic Elastic Cloud Software release to date. With this new EECS release, Exalogic customers now have an ideal platform for not only high-performance and mission critical applications, but for standardization and consolidation of virtually all Oracle Fusion Middleware, Fusion Applications, Application Unlimited and Oracle GBU Applications. With the release of EECS 2.0.1, Exalogic is now capable of hosting multiple concurrent tenants, business applications and middleware deployments with fine-grained resource management, enterprise-grade security, unmatched manageability and extreme performance in a fully virtualized environment. The Exalogic Elastic Cloud Software 2.0.1 release brings important new technologies to the Exalogic platform: Exalogic is now capable of hosting multiple concurrent tenants, business applications and middleware deployments with fine-grained resource management, enterprise-grade security, unmatched manageabi! lity and extreme performance in a fully virtualized environment. Support for extremely high-performance x86 server virtualization via a highly optimized version of Oracle VM 3.x. A rich, fully integrated Infrastructure-as-a-Service management system called Exalogic Control which provides graphical, command line and Java interfaces that allows Cloud Users, or external systems, to create and manage users, virtual servers, virtual storage and virtual network resources. Webcast Series: Rethink Your Business Application Deployment Strategy Redefining the CRM and E-Commerce Experience with Oracle Exalogic, 7-Jun@10am PT & On-Demand: ‘The Road to a Cloud-Enabled, Infinitely Elastic Application Infrastructure’ (featuring Gartner Analysts). WebLogic Partner Community For regular information become a member in the WebLogic Partner Community please visit: http://www.oracle.com/partners/goto/wls-emea ( OPN account required). If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Wiki Technorati Tags: ExaLogic Elastic Cloud,ExaLogic,WebLogic,WebLogic Community,Oracle,OPN,Jürgen Kress,ExaLogic 2.0.1

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• C++: calling non-member functions with the same syntax of member ones

  - by peoro

  One thing I'd like to do in C++ is to call non-member functions with the same syntax you call member functions: class A { }; void f( A & this ) { /* ... */ } // ... A a; a.f(); // this is the same as f(a); Of course this could only work as long as f is not virtual (since it cannot appear in A's virtual table. f doesn't need to access A's non-public members. f doesn't conflict with a function declared in A (A::f). I'd like such a syntax because in my opinion it would be quite comfortable and would push good habits: calling str.strip() on a std::string (where strip is a function defined by the user) would sound a lot better than calling strip( str );. most of the times (always?) classes provide some member functions which don't require to be member (ie: are not virtual and don't use non-public members). This breaks encapsulation, but is the most practical thing to do (due to point 1). My question here is: what do you think of such feature? Do you think it would be something nice, or something that would introduce more issues than the ones it aims to solve? Could it make sense to propose such a feature to the next standard (the one after C++0x)? Of course this is just a brief description of this idea; it is not complete; we'd probably need to explicitly mark a function with a special keyword to let it work like this and many other stuff.

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• How do you setup Postfix/Dovecot/MySQL to not look for local accounts?

  - by thiesdiggity

  I am having an issue with one of my Postfix/Dovecot mail servers and I'm unsure how to fix the problem. I will try to explain it in detail, here it goes: I have an Ubuntu server setup using Virtual hosting with Postfix, Dovecot and MySQL. We have one domain setup as a virtual domain, for this example I am going to use mail.example.com. Under that domain we have one email address. I have another server (MS Exchange) setup using another one of my sub-domains, ex.example.com. The problem is that when I SMTP into the account on mail.example.com and try to send an email to an account on ex.example.com, I get the email returned back to us with an "unknown host" error. Now, I know that the mail.example.com server can resolve the ex.example.com domain because I can ping/dig while SSH'd into it. I can also log into Postfix via Telnet and send an email to an ex.example.com mailbox. I'm guessing that it has something to do with Postfix/Dovecot looking locally for the domain in the virtual domain list because of the tld domain (example.com)? If that's the case, how do I get Postfix/Dovecot to only look locally for the entire URL (mail.example.com) and if it doesn't find it, send it to the correct server by looking up the MX/A records (which I know exist and are setup correctly)? I have been working on this all day and any guidance would be GREATLY appreciated! Thanks for your time!

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• Reporting Solution in PHP / CodeIgniter - Server side logic vs client side

  - by dot

  I'm building a report for an end user. They would like to see a list of all widgets... but then also like to see widgets with missing attributes, like missing names, or missing size. So i was thinking of creating one method that returns json data containing all widgets... and then using javascript to let them filter the data for missing data, instead of requerying the database. Ultimately, they need to be able to save all "reports" (filtered versions of data) inside a csv file. These are the two options I'm mulling over: Design 1 Create 3 separate methods in my controller/model like: get_all_data() get_records_with_missing_names() get_records_with_missing_size() And then when these methods are called, I would display the data on screen and give them a button to save to csv file. Design 2 Create one method called get_all_data() and then somehow, give them tools in the view to filter the json data using tables etc... and then letting them save subsets of the data. The reality is, in order to display all data, I still need to massage the data, and therefore, I know which records are missing attributes. So i'd rather not create separate methods by each filter. I'm not sure how I would do that just yet but at this point, i would like to know some pros/cons of each method. Thanks.

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• Semantic coupling vs. large class

  - by user106587

  I have hardware I communicate with via TCP. This hardware accepts ~40 different commands/requests with about 20 different responses. I've created a HardwareProxy class which has a TcpClient to send and receive data. I didn't like the idea of having 40 different methods to send the commands/requests, so I started down the path of having a single SendCommand method which takes an ICommand and returns an IResponse, this results in 40 different SpecificCommand classes. The problem is this requires semantic coupling, i.e. the method that invokes SendCommand receives an IResponse which it has to downcast to SpecificResponse, I use a future map which I believe ensures the appropriate SpecificResponse, but I get the impression this code smells. Besides the semantic coupling, ICommand and IResponse are essentially empty abstract classes (Marker Interfaces) and this seems suspicious to me. If I go with the 40 methods I don't think I have broken the single responisbility principle as the responsibility of the HardwareProxy class is to act as the hardware, which has all of these commands. This route is just ugly, plus I'd like to have Asynchronous versions, so there'd be about 80 methods. Is it better to bite the bullet and have a large class, accept the coupling and MarkerInterfaces for a smaller soultuion, or am I missing a better way? Thanks.

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• How to host an AP or a hotspot?

  - by user1048138

  I'm running Ubuntu 12.04 as a virtual machine on my Mac. Since I am unable to get the virtual machine to have full access to my WiFi card, I bought another USB WiFi card to use. This is my WiFi card. If you are unfamiliar with Virtual machine, as far as I know, since the Ubuntu has its own card now, it shouldn't matter. I have followed these guides with no luck: https://help.ubuntu.com/community/WifiDocs/WirelessAccessPoint http://www.danbishop.org/2011/12/11/using-hostapd-to-add-wireless-access-point-capabilities-to-an-ubuntu-server/ The problem is that the WiFi connection appears on all of the machines that I have in my house: 2 iPhones, Dell machine running Ubuntu and two Macbooks. However the connection times out on all of these machines. Questions: Could this be a driver issue if that same WiFi card can connect to other WiFi points and use its internet Could this be DHCP related? I would think not. It should at least get a 169.X.X.X address? No? Any solutions for me?

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• How do I drag my widgets without dragging other widgets?

  - by Cypher

  I have a bunch of drag-able widgets on screen. When I am dragging one of the widgets around, if I drag the mouse over another widget, that widget then gets "snagged" and is also dragged around. While this is kind of a neat thing and I can think of a few game ideas based on that alone, that was not intended. :-P Background Info I have a Widget class that is the basis for my user interface controls. It has a bunch of properties that define it's size, position, image information, etc. It also defines some events, OnMouseOver, OnMouseOut, OnMouseClick, etc. All of the event handler functions are virtual, so that child objects can override them and make use of their implementation without duplicating code. Widgets are not aware of each other. They cannot tell each other, "Hey, I'm dragging so bugger off!" Source Code Here's where the widget gets updated (every frame): public virtual void Update( MouseComponent mouse, KeyboardComponent keyboard ) { // update position if the widget is being dragged if ( this.IsDragging ) { this.Left -= (int)( mouse.LastPosition.X - mouse.Position.X ); this.Top -= (int)( mouse.LastPosition.Y - mouse.Position.Y ); } ... // define and throw other events if ( !this.WasMouseOver && this.IsMouseOver && mouse.IsButtonDown( MouseButton.Left ) ) { this.IsMouseDown = true; this.MouseDown( mouse, new EventArgs() ); } ... // define and throw other events } And here's the OnMouseDown event where the IsDraggable property gets set: public virtual void OnMouseDown( object sender, EventArgs args ) { if ( this.IsDraggable ) { this.IsDragging = true; } } Problem Looking at the source code, it's obvious why this is happening. The OnMouseDown event gets fired whenever the mouse is hovered over the Widget and when the left mouse button is "down" (but not necessarily in that order!). That means that even if I hold the mouse down somewhere else on screen, and simply move it over anything that IsDraggable, it will "hook" onto the mouse and go for a ride. So, now that it's obvious that I'm Doing It Wrong™, how do I do this correctly?

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• Good design for class with similar constructors

  - by RustyTheBoyRobot

  I was reading this question and thought that good points were made, but most of the solutions involved renaming one of the methods. I am refactoring some poorly written code and I've run into this situation: public class Entity { public Entity(String uniqueIdentifier, boolean isSerialNumber) { if (isSerialNumber) { this.serialNumber = uniqueIdentifier; //Lookup other data } else { this.primaryKey = uniqueIdentifier; // Lookup other data with different query } } } The obvious design flaw is that someone needed two different ways to create the object, but couldn't overload the constructor since both identifiers were of the same type (String). Thus they added a flag to differentiate. So, my question is this: when this situation arises, what are good designs for differentiating between these two ways of instantiating an object? My First Thoughts You could create two different static methods to create your object. The method names could be different. This is weak because static methods don't get inherited. You could create different objects to force the types to be different (i.e., make a PrimaryKey class and a SerialNumber class). I like this because it seems to be a better design, but it also is a pain to refactor if serialNumber is a String everywhere else.

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• Pros and Cons of Facebook's React vs. Web Components (Polymer)

  - by CletusW

  What are the main benefits of Facebook's React over the upcoming Web Components spec and vice versa (or perhaps a more apples-to-apples comparison would be to Google's Polymer library)? According to this JSConf EU talk and the React homepage, the main benefits of React are: Decoupling and increased cohesion using a component model Abstraction, Composition and Expressivity Virtual DOM & Synthetic events (which basically means they completely re-implemented the DOM and its event system) Enables modern HTML5 event stuff on IE 8 Server-side rendering Testability Bindings to SVG, VML, and <canvas> Almost everything mentioned is being integrated into browsers natively through Web Components except this virtual DOM concept (obviously). I can see how the virtual DOM and synthetic events can be beneficial today to support old browsers, but isn't throwing away a huge chunk of native browser code kind of like shooting yourself in the foot in the long term? As far as modern browsers are concerned, isn't that a lot of unnecessary overhead/reinventing of the wheel? Here are some things I think React is missing that Web Components will care of. Correct me if I'm wrong. Native browser support (read "guaranteed to be faster") Write script in a scripting language, write styles in a styling language, write markup in a markup language. Style encapsulation using Shadow DOM React instead has this, which requires writing CSS in JavaScript. Not pretty. Two-way binding

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• Modular Architecture for Processing Pipeline

  - by anjruu

  I am trying to design the architecture of a system that I will be implementing in C++, and I was wondering if people could think of a good approach, or critique the approach that I have designed so far. First of all, the general problem is an image processing pipeline. It contains several stages, and the goal is to design a highly modular solution, so that any of the stages can be easily swapped out and replaced with a piece of custom code (so that the user can have a speed increase if s/he knows that a certain stage is constrained in a certain way in his or her problem). The current thinking is something like this: struct output; /*Contains the output values from the pipeline.*/ class input_routines{ public: virtual foo stage1(...){...} virtual bar stage2(...){...} virtual qux stage3(...){...} ... } output pipeline(input_routines stages); This would allow people to subclass input_routines and override whichever stage they wanted. That said, I've worked in systems like this before, and I find the subclassing and the default stuff tends to get messy, and can be difficult to use, so I'm not giddy about writing one myself. I was also thinking about a more STLish approach, where the different stages (there are 6 or 7) would be defaulted template parameters. Can anyone offer a critique of the pattern above, thoughts on the template approach, or any other architecture that comes to mind?

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• Matrices: Arrays or separate member variables?

  - by bjz

  I'm teaching myself 3D maths and in the process building my own rudimentary engine (of sorts). I was wondering what would be the best way to structure my matrix class. There are a few options: Separate member variables: struct Mat4 { float m11, m12, m13, m14, m21, m22, m23, m24, m31, m32, m33, m34, m41, m42, m43, m44; // methods } A multi-dimensional array: struct Mat4 { float[4][4] m; // methods } An array of vectors struct Mat4 { Vec4[4] m; // methods } I'm guessing there would be positives and negatives to each. From 3D Math Primer for Graphics and Game Development, 2nd Edition p.155: Matrices use 1-based indices, so the first row and column are numbered 1. For example, a12 (read “a one two,” not “a twelve”) is the element in the first row, second column. Notice that this is different from programming languages such as C++ and Java, which use 0-based array indices. A matrix does not have a column 0 or row 0. This difference in indexing can cause some confusion if matrices are stored using an actual array data type. For this reason, it’s common for classes that store small, fixed size matrices of the type used for geometric purposes to give each element its own named member variable, such as float a11, instead of using the language’s native array support with something like float elem[3][3]. So that's one vote for method one. Is this really the accepted way to do things? It seems rather unwieldy if the only benefit would be sticking with the conventional math notation.

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• Take a snapshot with JavaFX!

  - by user12610255

  JavaFX 2.2 has a "snapshot" feature that enables you to take a picture of any node or scene. Take a look at the API Documentation and you will find new snapshot methods in the javafx.scene.Scene class. The most basic version has the following signature: public WritableImage snapshot(WritableImage image) The WritableImage class (also introduced in JavaFX 2.2) lives in the javafx.scene.image package, and represents a custom graphical image that is constructed from pixels supplied by the application. In fact, there are 5 new classes in javafx.scene.image: PixelFormat: Defines the layout of data for a pixel of a given format. WritablePixelFormat: Represents a pixel format that can store full colors and so can be used as a destination format to write pixel data from an arbitrary image. PixelReader: Defines methods for retrieving the pixel data from an Image or other surface containing pixels. PixelWriter: Defines methods for writing the pixel data of a WritableImage or other surface containing writable pixels. WritableImage: Represents a custom graphical image that is constructed from pixels supplied by the application, and possibly from PixelReader objects from any number of sources, including images read from a file or URL. The API documentation contains lots of information, so go investigate and have fun with these useful new classes! -- Scott Hommel

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• How do you plan your asynchronous code?

  - by NullOrEmpty

  I created a library that is a invoker for a web service somewhere else. The library exposes asynchronous methods, since web service calls are a good candidate for that matter. At the beginning everything was just fine, I had methods with easy to understand operations in a CRUD fashion, since the library is a kind of repository. But then business logic started to become complex, and some of the procedures involves the chaining of many of these asynchronous operations, sometimes with different paths depending on the result value, etc.. etc.. Suddenly, everything is very messy, to stop the execution in a break point it is not very helpful, to find out what is going on or where in the process timeline have you stopped become a pain... Development becomes less quick, less agile, and to catch those bugs that happens once in a 1000 times becomes a hell. From the technical point, a repository that exposes asynchronous methods looked like a good idea, because some persistence layers could have delays, and you can use the async approach to do the most of your hardware. But from the functional point of view, things became very complex, and considering those procedures where a dozen of different calls were needed... I don't know the real value of the improvement. After read about TPL for a while, it looked like a good idea for managing tasks, but in the moment you have to combine them and start to reuse existing functionality, things become very messy. I have had a good experience using it for very concrete scenarios, but bad experience using them broadly. How do you work asynchronously? Do you use it always? Or just for long running processes? Thanks.

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