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  • Growing your VirtualBox Virtual Disk

    - by Fat Bloke
    Don't you just hate it when this happens: Fortunately, if you're running inside VirtualBox, you can resize your virtual disk and magically make your guest have a bigger disk very easily. There are 2 steps to doing this... 1. Resize the virtual disk Use the VBoxManage command line tool to extend the size of the Virtual Disk, specifying the path to the disk and the size in MB: VBoxManage modifyhd <uuid>|<filename> [--type normal|writethrough|immutable|shareable| readonly|multiattach] [--autoreset on|off] [--compact] [--resize <megabytes>|--resizebyte <bytes>]   If you booted up your guest at this point, the extra space is seen as an unformatted area on the disk, like this: So we now need to tell the guest about the extra space available. 2. Extend the guest's partition to use the extra space How you do this step depends on you guest OS type and the tools you have available. Linux guests often include the excellent gparted partition editor, whereas Windows 7 and 8 provide the Computer Management tool which can resize partitions. Unfortunately, my Windows XP vm has no such tool. But I do have a couple of other options: Most Linux installable .isos include the aforementioned gparted tool, so I could simply attach, say, an Ubuntu.iso as a Virtual CD/DVD in my Windows XP vm and boot off that. Then use gparted to extend the Windows XP partition, before finally rebooting. But I took another route and attached my resized virtual disk to a Windows Server 2012 vm I had lying around. Then I used the Computer Management tool in Windows Server 2012 to extend the partition of the Windows XP disk, before shutting down, unplugging the disk and reattaching to my Windows XP vm. (Note that if your vm's use different disk controllers, Windows will check the disks on booting). When I finally boot up my Windows XP guest I see the available disk space and all is well. At least until the next time - FB 

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  • Inheritence and usage of dynamic_cast

    - by Mewzer
    Hello, Suppose I have 3 classes as follows (as this is an example, it will not compile!): class Base { public: Base(){} virtual ~Base(){} virtual void DoSomething() = 0; virtual void DoSomethingElse() = 0; }; class Derived1 { public: Derived1(){} virtual ~Derived1(){} virtual void DoSomething(){ ... } virtual void DoSomethingElse(){ ... } virtual void SpecialD1DoSomething{ ... } }; class Derived2 { public: Derived2(){} virtual ~Derived2(){} virtual void DoSomething(){ ... } virtual void DoSomethingElse(){ ... } virtual void SpecialD2DoSomething{ ... } }; I want to create an instance of Derived1 or Derived2 depending on some setting that is not available until run-time. As I cannot determine the derived type until run-time, then do you think the following is bad practice?... class X { public: .... void GetConfigurationValue() { .... // Get configuration setting, I need a "Derived1" b = new Derived1(); // Now I want to call the special DoSomething for Derived1 (dynamic_cast<Derived1*>(b))->SpecialD1DoSomething(); } private: Base* b; }; I have generally read that usage of dynamic_cast is bad, but as I said, I don't know which type to create until run-time. Please help!

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  • Inheritance, commands and event sourcing

    - by Arthis
    In order not to redo things several times I wanted to factorize common stuff. For Instance, let's say we have a cow and a horse. The cow produces milk, the horse runs fast, but both eat grass. public class Herbivorous { public void EatGrass(int quantity) { var evt= Build.GrassEaten .WithQuantity(quantity); RaiseEvent(evt); } } public class Horse : Herbivorous { public void RunFast() { var evt= Build.FastRun; RaiseEvent(evt); } } public class Cow: Herbivorous { public void ProduceMilk() { var evt= Build.MilkProduced; RaiseEvent(evt); } } To eat Grass, the command handler should be : public class EatGrassHandler : CommandHandler<EatGrass> { public override CommandValidation Execute(EatGrass cmd) { Contract.Requires<ArgumentNullException>(cmd != null); var herbivorous= EventRepository.GetById<Herbivorous>(cmd.Id); if (herbivorous.IsNull()) throw new AggregateRootInstanceNotFoundException(); herbivorous.EatGrass(cmd.Quantity); EventRepository.Save(herbivorous, cmd.CommitId); } } so far so good. I get a Herbivorous object , I have access to its EatGrass function, whether it is a horse or a cow doesn't matter really. The only problem is here : EventRepository.GetById<Herbivorous>(cmd.Id) Indeed, let's imagine we have a cow that has produced milk during the morning and now wants to eat grass. The EventRepository contains an event MilkProduced, and then come the command EatGrass. With the CommandHandler, we are no longer in the presence of a cow and the herbivorious doesn't know anything about producing milk . what should it do? Ignore the event and continue , thus allowing the inheritance and "general" commands? or throw an exception to forbid execution, it would mean only CowEatGrass, and HorseEatGrass might exists as commands ? Thanks for your help, I am just beginning with these kinds of problem, and I would be glad to have some news from someone more experienced.

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  • Code contracts and inheritance

    - by DigiMortal
    In my last posting about code contracts I introduced you how to force code contracts to classes through interfaces. In this posting I will go step further and I will show you how code contracts work in the case of inherited classes. As a first thing let’s take a look at my interface and code contracts. [ContractClass(typeof(ProductContracts))] public interface IProduct {     int Id { get; set; }     string Name { get; set; }     decimal Weight { get; set; }     decimal Price { get; set; } }   [ContractClassFor(typeof(IProduct))] internal sealed class ProductContracts : IProduct {     private ProductContracts() { }       int IProduct.Id     {         get         {             return default(int);         }         set         {             Contract.Requires(value > 0);         }     }       string IProduct.Name     {         get         {             return default(string);         }         set         {             Contract.Requires(!string.IsNullOrWhiteSpace(value));             Contract.Requires(value.Length <= 25);         }     }       decimal IProduct.Weight     {         get         {             return default(decimal);         }         set         {             Contract.Requires(value > 3);             Contract.Requires(value < 100);         }     }       decimal IProduct.Price     {         get         {             return default(decimal);         }         set         {             Contract.Requires(value > 0);             Contract.Requires(value < 100);         }     } } And here is the product class that inherits IProduct interface. public class Product : IProduct {     public int Id { get; set; }     public string Name { get; set; }     public virtual decimal Weight { get; set; }     public decimal Price { get; set; } } if we run this code and violate the code contract set to Id we will get ContractException. public class Program {     static void Main(string[] args)     {         var product = new Product();         product.Id = -100;     } }   Now let’s make Product to be abstract class and let’s define new class called Food that adds one more contract to Weight property. public class Food : Product {     public override decimal Weight     {         get         {             return base.Weight;         }         set         {             Contract.Requires(value > 1);             Contract.Requires(value < 10);               base.Weight = value;         }     } } Now we should have the following rules at place for Food: weight must be greater than 1, weight must be greater than 3, weight must be less than 100, weight must be less than 10. Interesting part is what happens when we try to violate the lower and upper limits of Food weight. To see what happens let’s try to violate rules #2 and #4. Just comment one of the last lines out in the following method to test another assignment. public class Program {     static void Main(string[] args)     {         var food = new Food();         food.Weight = 12;         food.Weight = 2;     } } And here are the results as pictures to see where exceptions are thrown. Click on images to see them at original size. Violation of lower limit. Violation of upper limit. As you can see for both violations we get ContractException like expected. Code contracts inheritance is powerful and at same time dangerous feature. Although you can always narrow down the conditions that come from more general classes it is possible to define impossible or conflicting contracts at different points in inheritance hierarchy.

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  • Inheritance vs containment while extending a large legacy project

    - by Flot2011
    I have got a legacy Java project with a lot of code. The code uses MVC pattern and is well structured and well written. It also has a lot of unit tests and it is still actively maintained (bug fixing, minor features adding). Therefore I want to preserve the original structure and code style as much as possible. The new feature I am going to add is a conceptual one, so I have to make my changes all over the code. In order to minimize changes I decided not to extend existing classes but to use containment: class ExistingClass { // .... existing code // my code adding new functionality private ExistingClassExtension extension = new ExistingClassExtension(); public ExistingClassExtension getExtension() {return extension;} } ... // somewhere in code ExistingClass instance = new ExistingClass(); ... // when I need a new functionality instance.getExtension().newMethod1(); All functionality that I am adding is inside a new ExistingClassExtension class. Actually I am adding only these 2 lines to each class that needs to be extended. By doing so I also do not need to instantiate new, extended classes all over the code and I may use existing tests to make sure there is no regression. However my colleagues argue that in this situation doing so isn't a proper OOP approach, and I need to inherit from ExistingClass in order to add a new functionality. What do you think? I am aware of numerous inheritance/containment questions here, but I think my question is different.

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  • Virtual Earth Shape Rendering Performance

    - by Mike
    I am overlaying a transparent image on my VEMap control by rendering it as a single VEShape. The shape changes sizes dynamically depeding on the zoom level of my map and can be as large as 4000*4000px. In older browsers such as IE6 and early versions of Firefox 2.x, map control performance degrades rapidly when my shape gets larger than 1500*1500px. The mouse pointer moves slowly and the map responds very slowly to events. I don't see this issue at all in newer browsers (IE7+). Are there any workarounds to boost performance of rendering a large shape for IE6 users?

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  • cannot get ip address on a virtual machine

    - by user175084
    so i have a code which gets me the ip address of a machine i am wroking on. so if my gui is published on the server and i access it from my local machine it gives me tha address of my local machine and when i access the gui from the server itself it gives me the server address.. which is fine. But when i put the gui on a VM server and run it from a VM server itself i dont get the ip address. this works fine if i access it from another machine but does not work only when accesing gui on VM server.. please help me out as i get this value ":::1" here is my code: string ipaddress; //string ipaddress = Request.ServerVariables["LOCAL_ADDR"]; string ipaddress = Request.ServerVariables["HTTP_X_FORWARDED_FOR"]; if (ipaddress == "" || ipaddress == null) string ipaddress = Request.ServerVariables["REMOTE_ADDR"]; Label5.Text = ipaddress; thank you

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  • Modeling a cellphone bill: should I use single-table inheritance or polymorphic associations?

    - by Horace Loeb
    In my domain: Users have many Bills Bills have many BillItems (and therefore Users have many BillItems through Bills) Every BillItem is one of: Call SMS (text message) MMS (multimedia message) Data Here are the properties of each individual BillItem (some are common): My question is whether I should model this arrangement with single-table inheritance (i.e., one "bill_items" table with a "type" column) or polymorphism (separate tables for each BillItem type), and why.

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  • Virtual-machine running from DVD ?

    - by umanga
    Greetings all, I have this application which uses Tomcat and PostgreSQL (only involve database reads, no writes). I need to make this application runnable from a DVD.(target platform is Windows). So I was thinking to do these: 1) In a VirtualMachine (i prefer virtualbox) install lightweight linux distro. 2) Install Tomcat and Postgre, 3) Write virtualmachine into DVD which loads above virtualmachine image automatically when executed. But I am not quite sure whether I can do step 3.Or is it possible ? Any tips?

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  • Real server, Multiple IP Addresses, HyperV Virtual Server, How to partition IPs across real and Virtual NICs

    - by Steven_W
    This is a slightly difficult problem to explain without same basic background information - I'll try and refine the question later as necessary Originally, I have a single hosted server (Win 2008R2) with the following range of 8 IP addresses. - Single NIC - IP: x.x.128.72 -> x.x.128.79 - Subnet: x.x.255.192 - GW: x.x.128.65 After installing Hyper-V and setting up a single virtual server on the same box, I then wanted to assign one of the IP addresses to the virtual server, leaving everything else running normally. -- Firstly, I tried using the "External" network, but (even after setting IPs on the "Virtual Adapter" similar to Here but struggled to get networking running at all. I needed to keep the server running (otherwise I would have spent more time pursuing this approach) Q1 ... Was this a sensible thing to do ? Should I have carried on down this route ? -- I then decided to try different approach - Set the HyperV network to "Internal" (visible to Management OS) - Physical NIC - IP: x.x.128.72 -> x.x.128.75 - Subnet: x.x.255.192 - GW: x.x.128.65 - Virtual NIC - IP: x.x.128.78 - Subnet: x.x.255.252 - GW: x.x.128.72 ... { The same as the IP of the physical NIC ) - Virtual OS-NIC - IP: x.x.128.77 - Subnet: x.x.255.252 - GW: x.x.128.78 ... { The same as the IP of the host virtual-NIC ) -- Surprisingly enough, this approach actually worked, and I was able to connect from all the following: - Internet to/from physical NIC (x.x.128.72) - physical NIC (x.x.128.72) to virtual-OS-NIC (x.x.128.77) e.g. testing via ping + FTP - Internet to/from virtual-OS-NIC (x.x.128.72) -- The problem I have is that this approach seems to only last for a short while (a few hours). After this time, it seems that I lose the ability to connect from Virtual-OS-NIC to/from the internet (but I can still connect from the host-OS to the virtual-OS and from the host-OS to the internet) I have re-tested this a couple of times with the same results ... I leave the server on for a few hours (e.g. overnight), and when I come back in the morning, the Virtual-OS loses the ability to route to the internet -- I'm not quite sure what to look at next (or whether I'm going about this completely the wrong way ) One "possible relevant item" is that the host-OS is also running RRAS (Routing and Remote Access), but this is only to run a simple VPN -- Q2 - Wheat should I be looking at next ? (Any good references / recommendations of what to try) Would appreciate any thoughts or comments (even if you tell me I'm going about this the wrong way)

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  • Is it possible to limit how much CPU a virtual machine can use with VMWare Player?

    - by Raz
    Is it possible to limit how much CPU a virtual machine can use with VMWare Player? I use VMWare to run a Windows XP virtual machine. I want to keep it on in the background all the time. The real computer runs Windows 7 and is sometimes a little bit short of memory. That's why I want to check if I can throttle the VM down to the bare minimum to keep it running in the background constantly without interfering too much.

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  • How to stream sound from an esx virtual machine ?

    - by Adrien
    Hi, I try to play sound from my monitoring application, which is an xp virtual machine on VMware ESX 3, on a physical machine with a real sound card, but I can not add from the ESX console sound card. Currently, I transmit sound with opening an RDP session and play it in this session. I would like to play sound without openning RDP session, do you have a solution to add a virtual sound card and then stream it with vlc?

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  • Can I install a Windows 8 Pro upgrade in a virtual machine?

    - by Dean Schulze
    I bought a Lenovo 430K with Windows 7 Home Premium and upgraded it to Windows 8 Pro. I created a DVD from which I installed the Windows 8 Pro upgrade. I'm underwhelmed with Windows 8, however. I want to install Linux as the host OS and run Windows 8 Pro as a guest OS. Will the Windows 8 Pro DVD that I created install Windows 8 Pro in a virtual machine, or would that virtual machine have to have Windows 7 installed first in order to install the upgrade?

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  • Is it possible to run several virtual machines each with independent mouse+keyboard on a single PC?

    - by chiurox
    My goal is to instead of buying 4 separate basic PCs (plus the obvious peripherals), buy just one fast PC and the peripherals. I'm wondering if I can use a more powerful computer, say, one with core i7 and plenty of RAM, with 2 video cards (total of 4 monitor outputs) to run 4 or more virtual machines (WinXPs) so instead of having 4 individual machines, I'll be having just one. However, the catch is, is it possible to have a pair of mouse and keyboard + input/output audio for each of these virtual machines?

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  • Top - what does Virtual memory size mean? ...linux/ubuntu

    - by user42159
    I am running Top to monitor my server performance and 2 of my java processes show virtual memory of upto 800MB-1GB. Is that a bad thing? What does virtual memory mean? And oh btw, I have swap of 1GB and it shoes 0% used. So I am confused. Java process = 1 Tomcat server + my own java deamon Server = Ubuntu 9.10 (karmic)

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  • How can I copy an XP Mode virtual machine from one computer to another?

    - by Investor5555
    Is it possible to copy an XP Mode Virtual PC image from one computer to a completely different computer (not on the network, not related in any way whatsoever)? I tried this, but it only would seem to work on the same computer: http://www.sevenforums.com/tutorials/21904-virtual-xp-machine-copy.html When I copy it to another computer and modify the settings as described above, the cursor just jumps around all over the screen and never starts.

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  • Can I read a smartcard in a virtual machine?

    - by endian
    My employer requires a smartcard to login to their web-based remote working platform. I want to access this platform by using a Remote Desktop Connection on to my Windows 7 Virtual Machine, with the smartcard plugged into my home PC. However, whilst I can see the smartcard on my home PC, it doesn't appear in the virtual machine, despite me having "Smart Cards" enabled in the Local Resources page of Remote Desktop Connection. Is it possible to get this working?

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  • Virtualnetwork with virtualbox

    - by vpereira
    I would like to test a firewall solution. For that i would like to create a virtual network, without contact with my network and configure two virtual ethernet cards in my firewall. is that possible? say that my virtual machine has two ethernets? If with virtualbox is not possible, is it possible with any VM solution? To create virtual network and virtual devices in my virtual operational system

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  • JavaScript objects and Crockford's The Good Parts

    - by Jonathan
    I've been thinking quite a bit about how to do OOP in JS, especially when it comes to encapsulation and inheritance, recently. According to Crockford, classical is harmful because of new(), and both prototypal and classical are limited because their use of constructor.prototype means you can't use closures for encapsulation. Recently, I've considered the following couple of points about encapsulation: Encapsulation kills performance. It makes you add functions to EACH member object rather than to the prototype, because each object's methods have different closures (each object has different private members). Encapsulation forces the ugly "var that = this" workaround, to get private helper functions to have access to the instance they're attached to. Either that or make sure you call them with privateFunction.apply(this) everytime. Are there workarounds for either of two issues I mentioned? if not, do you still consider encapsulation to be worth it? Sidenote: The functional pattern Crockford describes doesn't even let you add public methods that only touch public members, since it completely forgoes the use of new() and constructor.prototype. Wouldn't a hybrid approach where you use classical inheritance and new(), but also call Super.apply(this, arguments) to initialize private members and privileged methods, be superior?

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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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  • Hyper-V virtual machine can't be migrated to a specific host in the cluster

    - by Massimo
    I have a three-node Hyper-V cluster running on Windows Server 2008 R2 which is working quite flawlessly: there are no errors, live migration works, all hosts can and will happily run all virtual machines, and so on. But one specific virtual machinee is trying to make me go mad: it works on two nodes of the cluster, but not on the third one. Whenever I try to move the VM to that node, be it in a live migration or with the VM powered off, it always fails. In the event log of the host these events are logged: Source: Hyper-V-VMMS Event ID: 16300 Cannot load a virtual machine configuration: General access denied error (0x80070005) (Virtual machine ID <GUID>) Source: Hyper-V-VMMS Evend ID: 20100 The Virtual Machine Management Service failed to register the configuration for the virtual machine '<GUID>' at 'C:\ClusterStorage\<PATH>\<VM>': General access denied error (0x80070005) Source: Hyper-V-High-Availability Event ID: 21102 'Virtual Machine Configuration <VM>' failed to register the virtual machine with the virtual machine management service. All other VMs can be moved to/from the offending host, and the offending VM can be moved between the other two hosts. Also, this is not a storage problem, because there are other VMs in the same cluster volume, and the host has no troubles running them. What's going on here?

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  • One bigger Virtual Machine distributed across many Nodes [on hold]

    - by flyer
    I just setup virtual machines on one hardware with Vagrant (this is just a test environment, not production!). I want to use a Puppet to configure them and next try to setup OpenStack. I am not sure If I am understanding how this should look at the end. Is it possible to have below architecture with OpenStack after all where I will run one Virtual Machine with Linux? ------------------------------- | VM | ------------------------------- | NOVA | NOVA | NOVA | ------------------------------- | OpenStack | ------------------------------- | Node | Node | Node | ------------------------------- (In my environment Nodes are just virtual machines, but my question concerns separate Hardware nodes) After some comments... Is it a language barrier, or? This is only my 'virtual environment'. If we imagine this virtual machines are a separate Nodes (e.g. every has 4 cores) the OpenStack is still the same, right? Can I run one Virtual Machine across many Nodes with OpenStack? Is it possible to aggregate the computation power of separate machines in one virtual distributed operating system?

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