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• June 23, 1983: First Successful Test of the Domain Name System [Geek History]

  - by Jason Fitzpatrick

  Nearly 30 years ago the first Domain Name System (DNS) was tested and it changed the way we interacted with the internet. Nearly impossible to remember number addresses became easy to remember names. Without DNS you’d be browsing a web where numbered addresses pointed to numbered addresses. Google, for example, would look like http://209.85.148.105/ in your browser window. That’s assuming, of course, that a numbers-based web every gained enough traction to be popular enough to spawn a search giant like Google. How did this shift occur and what did we have before DNS? From Wikipedia: The practice of using a name as a simpler, more memorable abstraction of a host’s numerical address on a network dates back to the ARPANET era. Before the DNS was invented in 1983, each computer on the network retrieved a file called HOSTS.TXT from a computer at SRI. The HOSTS.TXT file mapped names to numerical addresses. A hosts file still exists on most modern operating systems by default and generally contains a mapping of the IP address 127.0.0.1 to “localhost”. Many operating systems use name resolution logic that allows the administrator to configure selection priorities for available name resolution methods. The rapid growth of the network made a centrally maintained, hand-crafted HOSTS.TXT file unsustainable; it became necessary to implement a more scalable system capable of automatically disseminating the requisite information. At the request of Jon Postel, Paul Mockapetris invented the Domain Name System in 1983 and wrote the first implementation. The original specifications were published by the Internet Engineering Task Force in RFC 882 and RFC 883, which were superseded in November 1987 by RFC 1034 and RFC 1035.Several additional Request for Comments have proposed various extensions to the core DNS protocols. Over the years it has been refined but the core of the system is essentially the same. When you type “google.com” into your web browser a DNS server is used to resolve that host name to the IP address of 209.85.148.105–making the web human-friendly in the process. Domain Name System History [Wikipedia via Wired] What is a Histogram, and How Can I Use it to Improve My Photos?How To Easily Access Your Home Network From Anywhere With DDNSHow To Recover After Your Email Password Is Compromised

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• design a model for a system of dependent variables

  - by dbaseman

  I'm dealing with a modeling system (financial) that has dozens of variables. Some of the variables are independent, and function as inputs to the system; most of them are calculated from other variables (independent and calculated) in the system. What I'm looking for is a clean, elegant way to: define the function of each dependent variable in the system trigger a re-calculation, whenever a variable changes, of the variables that depend on it A naive way to do this would be to write a single class that implements INotifyPropertyChanged, and uses a massive case statement that lists out all the variable names x1, x2, ... xn on which others depend, and, whenever a variable xi changes, triggers a recalculation of each of that variable's dependencies. I feel that this naive approach is flawed, and that there must be a cleaner way. I started down the path of defining a CalculationManager<TModel> class, which would be used (in a simple example) something like as follows: public class Model : INotifyPropertyChanged { private CalculationManager<Model> _calculationManager = new CalculationManager<Model>(); // each setter triggers a "PropertyChanged" event public double? Height { get; set; } public double? Weight { get; set; } public double? BMI { get; set; } public Model() { _calculationManager.DefineDependency<double?>( forProperty: model => model.BMI, usingCalculation: (height, weight) => weight / Math.Pow(height, 2), withInputs: model => model.Height, model.Weight); } // INotifyPropertyChanged implementation here } I won't reproduce CalculationManager<TModel> here, but the basic idea is that it sets up a dependency map, listens for PropertyChanged events, and updates dependent properties as needed. I still feel that I'm missing something major here, and that this isn't the right approach: the (mis)use of INotifyPropertyChanged seems to me like a code smell the withInputs parameter is defined as params Expression<Func<TModel, T>>[] args, which means that the argument list of usingCalculation is not checked at compile time the argument list (weight, height) is redundantly defined in both usingCalculation and withInputs I am sure that this kind of system of dependent variables must be common in computational mathematics, physics, finance, and other fields. Does someone know of an established set of ideas that deal with what I'm grasping at here? Would this be a suitable application for a functional language like F#? Edit More context: The model currently exists in an Excel spreadsheet, and is being migrated to a C# application. It is run on-demand, and the variables can be modified by the user from the application's UI. Its purpose is to retrieve variables that the business is interested in, given current inputs from the markets, and model parameters set by the business.

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• Flattening System.Web.UI ControlCollection

  - by evovision

  Hi,   Sometimes one may need to get a list of child controls inside specific container and don't care about the underlying hierarchy.   The result is beautifully achieved using this extension method:   using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;    public static class ControlCollectionExtensionMethods    {        public static IEnumerable<Control> FlattenedList(this ControlCollection controls)        {            foreach (Control ctrl in controls)            {                  // return parent control                   yield return ctrl;                              // and dive into child collection                   foreach (Control child in ctrl.Controls.FlattenedList())                         yield return child;            }        }    }   P.S.: don't forget about namespaces when using it in your code, if above class is wrapped into namespace, for example: Sample, the source code file with calling code must explicitly reference it: using Sample;

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• Used SQL Svr 2008 Config Manager to Set Service Account to Local System: What Did It Change?

  - by Frank Ramage

  Direct shot to foot moment... While setting-up individual non-admin accts for MSSQLSERVER services, I temporarily set Server service login to Local System account. I remembered later that: SQL Server Configuration Manager performs additional configuration such as setting permissions in the Windows Registry so that the new account can read the SQL Server settings. I want my Local System back . (Actually just restored to its original security profile) Any advice? Thanks!

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• Can the features of Dell OpenManage be replaced by Microsoft System Center?

  - by bwerks

  Hi all, I'm new to both OpenManage and System Center, but it sounds as if they're geared towards similar problems/goals. Are the features comparable enough that OpenManage can be forgone completely in favor of System Center products? Specifically I'm hoping to achieve storage monitoring and remote administration, although if someone with experience with both wants to provide a quick compare/contrast (objective, of course) I won't complain. Thanks!

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• Would it be possible to swap system restore points on different brands of computers?

  - by P'sao

  So I have a ThinkPad computer that I've installed a program called "Deep Freeze" which restores your computer to the "Frozen" state. I also have a Toshiba computer with no Deep Freeze on it. My question is that would it be possible to creat a system restore point on my Toshiba and then replace the system volume information folder with the one on the ThinkPad so I could restore to a point with no Deep Freeze? Would this work?

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• How do I minimize Evolution to the system tray in Ubuntu?

  - by Jephir

  In Ubuntu some applications can be set to minimize instead of exit on close. For example, Empathy minimizes to the system tray (mail icon) when the close button is pressed in the application window. How do I make Evolution do this as well? Essentially I would like to have Evolution hidden in the system tray instead of having to re-launch it every ten minutes to check for new messages (or leave it open and clutter the taskbar).

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• Reformatting and version control

  - by l0b0

  Code formatting matters. Even indentation matters. And consistency is more important than minor improvements. But projects usually don't have a clear, complete, verifiable and enforced style guide from day 1, and major improvements may arrive any day. Maybe you find that SELECT id, name, address FROM persons JOIN addresses ON persons.id = addresses.person_id; could be better written as / is better written than SELECT persons.id, persons.name, addresses.address FROM persons JOIN addresses ON persons.id = addresses.person_id; while working on adding more columns to the query. Maybe this is the most complex of all four queries in your code, or a trivial query among thousands. No matter how difficult the transition, you decide it's worth it. But how do you track code changes across major formatting changes? You could just give up and say "this is the point where we start again", or you could reformat all queries in the entire repository history. If you're using a distributed version control system like Git you can revert to the first commit ever, and reformat your way from there to the current state. But it's a lot of work, and everyone else would have to pause work (or be prepared for the mother of all merges) while it's going on. Is there a better way to change history which gives the best of all results: Same style in all commits Minimal merge work ? To clarify, this is not about best practices when starting the project, but rather what should be done when a large refactoring has been deemed a Good Thing™ but you still want a traceable history? Never rewriting history is great if it's the only way to ensure that your versions always work the same, but what about the developer benefits of a clean rewrite? Especially if you have ways (tests, syntax definitions or an identical binary after compilation) to ensure that the rewritten version works exactly the same way as the original?

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• How do you avoid name similarities between your classes and the native ones?

  - by Oscar

  I just ran into an "interesting problem", which I would like your opinion about: I am developing a system and for many reasons (meaning: abstraction, technology independence, etc) we create our own types for exchanging information. For instance: if there is a method which is called SendEmail and is invoked by the business logic, it way have a parameter of type OurCompany.EMailMessage, which is an object which is completely technology independent and contains only "business relevant data" (for instance, no information abut head encoding). Inside the SendEmail function, we get this information from our EMailMEssage object and create a MailMessage (this one is technolgy specific) object so it can be sent over the network. As you can already notice, our class has a very similar name to the "native" language class. The problem is: this is exactly what they are, email messages, so it is hard to find another meaningful name for them. Do you have this problem often? How do you manage it? Edit: @mgkrebbs just commented about using fully qualified names. This is our current approach, but a little bit too verbose, IMHO. I would like something cleaner, if possible.

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• Read-only file system

  - by John

  The title might not be as descriptive as I would like it to be but couldn't come up with a better one. My server's file system went into Read-only. And I don't understand why it does so and how to solve it. I can SSH into the server and when trying to start apache2 for example I get the following : username@srv1:~$ sudo service apache2 start [sudo] password for username: sudo: unable to open /var/lib/sudo/username/1: Read-only file system * Starting web server apache2 (30)Read-only file system: apache2: could not open error log file /var/log/apache2/error.log. Unable to open logs Action 'start' failed. The Apache error log may have more information. When I try restarting the server I get : username@srv1:~$ sudo shutdown -r now [sudo] password for username: sudo: unable to open /var/lib/sudo/username/1: Read-only file system Once I restart it manually it just start up without any warning or message saying something is wrong. I hope somebody could point me into the right direction to resolve this issue. Thanks in advance!

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• Boot failure after update and system crash 11.10

  - by Alubuntu

  I'm using: Dell XPS M1330 laptop, Ubuntu 11.10 32bits, single boot (only Linux OS), Virtualbox (with Windows XP on virtual machine). System crashed while working with a very heavy image on GIMP (and Virtualbox was on). During the same session, I made an automatic system update, but don't know what was exactly updated. After the crash the system doesn't boot. Always freezes on terminal screen but at different stages, ""Starting CUPS printing spooler/server", "Checking battery state", "mountall: plymouth command failed", etc. Sometimes indicates [failed] in some of the processes and sometimes they're all [ok]. Did a Boot info summary with boot-repair and gave me this report http://paste.ubuntu.com/1050743/ This is not a new install, have been using it for almost 6 months...though since last month it couldn't halt..it started shutting down and stopped at black screen with fan on and on/off light still on (I used to finish the shutdown process by forcing halt with a long-press of the power button). I don't know if these has anything to do with the boot failure. Is there anyway I can solve this issue (the boot failure) or make some sort of system check to find out what is the cause of the problem? I wasn't sure if this was the right place to ask the question, so I also did it at https://answers.launchpad.net/ubuntu/+question/201004

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• System boots in console + login loop

  - by Imagicien

  I messed up my system while trying to fix permission problems for setting up a LAMP local server. I tried this solution: How to avoid using sudo when working in /var/www? without success. Then I saw this solution: Permissions issue: how can Apache access files in my Home directory? I understood that I had to change the permissions of my root directory (among others), so I executed: sudo chmod 710 / I also changed the user group on / to www-data. I also did these operations on /home. I'm pretty sure one of those commands broke something, because it's the last commands I executed, and after that, my system showed strange/broken behavior: Firefox stopped showing pages Some icons got replaced by an red X icon (meaning "Icon not found" I guess) Applications refused to launch (no reaction) After rebooting: I got a strange graphical message talking about not being able to mount something, asking me if I wanted to wait, and talking about /tmp (I forgot the message since I was in shock) My system now boots in console, and when I login, it flashes unsignificant stuff* before re-asking me to login. My important data is on Ubuntu One. I'd prefer not having to reinstall from scratch. Is there a way to regain access to my system? Thanks a lot for your help. *Looks like a terminal header with the name of the OS and other info. Doesn't seem important.

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• What is an Enterprise Resource Planning (ERP) System?

  In order to understand what an Enterprise Resource Planning System is let us look at a classic American kids snack, the Rice Krispy Treat if we conceptually view the treat as a company’s internal applications as a whole.  Furthermore we can view a company’s departmentalized software applications as the theoretical Rice Krispies in the treat. In addition, the Rice Krispies consist of a combination of ingredients that be broken down into data, user interfaces and business logic. Next, we have the margarine or butter that is used to help the marshmallows bind with the Rice Krispies; this role in our conceptual view is taken by a data source typically as a relational database management system. Finally we have the melted marshmallows which act as the ERP software that connects all of the individual departmental software applications in to one unified system that allows all user one unified system to interact with all of the individual dispersed systems. An example of this would be if a customer places an order with a telephone operator and once the orders is processed an employee in the shipping department can see the order ready for fulfillment on his order screen. The ERP acts a go between for various independent departmental systems so that they can integrate with one another.

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• C++ and system exceptions

  - by Abyx

  Why standard C++ doesn't respect system (foreign or hardware) exceptions? E.g. when null pointer dereference occurs, stack isn't unwound, destructors aren't called, and RAII doesn't work. The common advice is "to use system API". But on certain systems, specifically Win32, this doesn't work. To enable stack unwinding for this C++ code // class Foo; // void bar(const Foo&); bar(Foo(1, 2)); one should generate something like this C code Foo tempFoo; Foo_ctor(&tempFoo); __try { bar(&tempFoo); } __finally { Foo_dtor(&tempFoo); } Foo_dtor(&tempFoo); and it's impossible to implement this as C++ library. Upd: Standard doesn't forbid handling system exceptions. But it seems that popular compilers like g++ doesn't respect system exceptions on any platforms just because standard doesn't require this. The only thing that I want - is to use RAII to make code readable and program reliable. I don't want to put hand-crafted try\finally around every call to unknown code. For example in this reusable code, AbstractA::foo is such unknown code: void func(AbstractA* a, AbstractB* b) { TempFile file; a->foo(b, file); } Maybe one will pass to func such implementation of AbstractA, which every Friday will not check if b is NULL, so access violation will happen, application will terminate and temporary file will not be deleted. How many months uses will suffer because of this issue, until either author of func or author of AbstractA will do something with it? Related: Is `catch(...) { throw; }` a bad practice?

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• Big level objects collision system for 2d game

  - by Aristarhys

  I read many variants today and get some knowledge in general, so here is a steps of mine thoughts in pictures (horrible paint.net ones). We need to develop grid system, so we check only thing near, perform simple check to cut out deep check, and at - last deep check like per-pixel collision check. Step 1 - Let p1, p2 are some sprites lets first just check with circle collision - because large distance between p1, p2 this fails and of course so we don't need test more deeply. But if we have not 2, but 20 objects, why we need to even circle test something so far outside of our view. Step 2 - Add basic column system, now we don't bother with p2 if it's in a column far from p1 column, so we even don't do circle test. But p3 is in the same col, so let do circle test, which of course will fail. Step 3 - Lets improve column system to the grid system with grid cell size just like p1, p2, p3 collision boxes, so we cut out things much top or below p1. And this is all great until comes BIG OBJs which is some kind of platforms. They are much bigger then grid cell. Circle test for will be successful, but deep check for whole big obj will fail And that the part I can't get. How do I store the grid position of big object? Like 4 grid coords for big object vertexes? And if one of them close to p1 do circle check for centre of big object then a deep one if succeed? Am I do it wrong? My possible solution:

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• Designing a system with different business rules for different customers

  - by user1595846

  My company is rewriting our proprietary business application. The current architecture is poorly done and inflexible. It is coded more procedural oriented as opposed to object oriented. It has become difficult to maintain. Our system is a web application written in .Net Webforms. I am considering ASP.Net MVC for the rewrite. We intend to rewrite it with a good, solid architecture with the goal of maintainability and reusable classes for some of our other systems and services. We would also like the system to be customizable for different customers in the event that we market the system. I am considering redesigning the system based on the layered architecture (Presentation, Business, Data Access layers) described in the Microsoft Patterns and Practices Application Architecture Guide. http://msdn.microsoft.com/en-us/library/ff650706.aspx Hopefully this isn't too open ended, but how would you recommend allowing for different business logic/rules for different customers? I'm aware of Windows Workflow Foundation, but from what I've read about it, it seems many business rules could be too complicated to handle there. Also, Can anyone point me to where I can download an example of a .net solution that is based on the Application Architecture Guide? I have already downloaded the Layered Architecture Solution Guidance and the Expense Sample on codeplex. I was looking for something a bit larger and more robust that I could step through the code and see how it works. If you feel there are better architectures to base our redesign on please feel free to share. I appreciate your help!

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• Complex, yet simple crafting system model

  - by KatShot

  I'm working on some arcade shooter/slasher, and the main logline is "Kick'em with everything you want". There's not so many enemies in GDD, main focus is on tons of weapons and gadgets to cause mayhem. To get weapon, you need to craft it, and now crafting system looks simple, like: 1) You got three slots for weapon parts (like A, B, C) 2) You collect misc weapon parts, and when you got atleast one for every slot, you can craft a weapon (for example, if you got A1, B1, B2, B3 and C1, you can craft such models - A1B1C1, A1B2C1, A1B3C1) As for me, this crafting system is too simple, because weapon parts will just fall from the top of screen, often enough. That's why I'm thinking about adding some more crafting system levels, like resources (collect 10 scrap pieces to make part A1 or C3), etc. My question is: How can i add some more complex, still simple, transparent levels in crafting system? upd. For example, in Minecraft or Terraria, first 5-10 crafting recipies quite transparent and simple IMHO. But then it turns into huge mess to understand, how to craft this or that (for example, fishing rod)

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• Iterate through deserialized xml object

  - by Bruce Adams

  I have a deserialized xml c# objet. I need to iterate through the oject to display all items, in this case there's just one, and display the name, colors and sizes for each item. The xml: <?xml version="1.0" encoding="utf-8"?> <Catalog Name="Example"> <Items> <Item Name="ExampleItem"> <Colors> <Color Name="Black" Value="#000" /> <Color Name="White" Value="#FFF" /> </Colors> <Sizes> <Size Name="Small" Value="10" /> <Size Name="Medium" Value="20" /> </Sizes> </Item> </Items> </Catalog> xsd.exe generated classes: //------------------------------------------------------------------------------ // <auto-generated> // This code was generated by a tool. // Runtime Version:2.0.50727.4927 // // Changes to this file may cause incorrect behavior and will be lost if // the code is regenerated. // </auto-generated> //------------------------------------------------------------------------------ using System.Xml.Serialization; // // This source code was auto-generated by xsd, Version=2.0.50727.42. // /// <remarks/> [System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "2.0.50727.42")] [System.SerializableAttribute()] [System.Diagnostics.DebuggerStepThroughAttribute()] [System.ComponentModel.DesignerCategoryAttribute("code")] [System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true)] [System.Xml.Serialization.XmlRootAttribute(Namespace="", IsNullable=false)] public partial class Catalog { private CatalogItemsItem[][] itemsField; private string nameField; /// <remarks/> [System.Xml.Serialization.XmlArrayAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified)] [System.Xml.Serialization.XmlArrayItemAttribute("Item", typeof(CatalogItemsItem[]), Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=false)] public CatalogItemsItem[][] Items { get { return this.itemsField; } set { this.itemsField = value; } } /// <remarks/> [System.Xml.Serialization.XmlAttributeAttribute()] public string Name { get { return this.nameField; } set { this.nameField = value; } } } /// <remarks/> [System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "2.0.50727.42")] [System.SerializableAttribute()] [System.Diagnostics.DebuggerStepThroughAttribute()] [System.ComponentModel.DesignerCategoryAttribute("code")] [System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true)] public partial class CatalogItemsItem { private CatalogItemsItemColorsColor[][] colorsField; private CatalogItemsItemSizesSize[][] sizesField; private string nameField; /// <remarks/> [System.Xml.Serialization.XmlArrayAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified)] [System.Xml.Serialization.XmlArrayItemAttribute("Color", typeof(CatalogItemsItemColorsColor[]), Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=false)] public CatalogItemsItemColorsColor[][] Colors { get { return this.colorsField; } set { this.colorsField = value; } } /// <remarks/> [System.Xml.Serialization.XmlArrayAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified)] [System.Xml.Serialization.XmlArrayItemAttribute("Size", typeof(CatalogItemsItemSizesSize[]), Form=System.Xml.Schema.XmlSchemaForm.Unqualified, IsNullable=false)] public CatalogItemsItemSizesSize[][] Sizes { get { return this.sizesField; } set { this.sizesField = value; } } /// <remarks/> [System.Xml.Serialization.XmlAttributeAttribute()] public string Name { get { return this.nameField; } set { this.nameField = value; } } } /// <remarks/> [System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "2.0.50727.42")] [System.SerializableAttribute()] [System.Diagnostics.DebuggerStepThroughAttribute()] [System.ComponentModel.DesignerCategoryAttribute("code")] [System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true)] public partial class CatalogItemsItemColorsColor { private string nameField; private string valueField; /// <remarks/> [System.Xml.Serialization.XmlAttributeAttribute()] public string Name { get { return this.nameField; } set { this.nameField = value; } } /// <remarks/> [System.Xml.Serialization.XmlAttributeAttribute()] public string Value { get { return this.valueField; } set { this.valueField = value; } } } /// <remarks/> [System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "2.0.50727.42")] [System.SerializableAttribute()] [System.Diagnostics.DebuggerStepThroughAttribute()] [System.ComponentModel.DesignerCategoryAttribute("code")] [System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true)] public partial class CatalogItemsItemSizesSize { private string nameField; private string valueField; /// <remarks/> [System.Xml.Serialization.XmlAttributeAttribute()] public string Name { get { return this.nameField; } set { this.nameField = value; } } /// <remarks/> [System.Xml.Serialization.XmlAttributeAttribute()] public string Value { get { return this.valueField; } set { this.valueField = value; } } } /// <remarks/> [System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "2.0.50727.42")] [System.SerializableAttribute()] [System.Diagnostics.DebuggerStepThroughAttribute()] [System.ComponentModel.DesignerCategoryAttribute("code")] [System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true)] [System.Xml.Serialization.XmlRootAttribute(Namespace="", IsNullable=false)] public partial class NewDataSet { private Catalog[] itemsField; /// <remarks/> [System.Xml.Serialization.XmlElementAttribute("Catalog")] public Catalog[] Items { get { return this.itemsField; } set { this.itemsField = value; } } } Deserialization code: System.Xml.Serialization.XmlSerializer xSerializer = new System.Xml.Serialization.XmlSerializer(typeof(Catalog)); TextReader reader = new StreamReader("catalog.xml"); Catalog catalog = (Catalog)xSerializer.Deserialize(reader); foreach (var item in catalog.Items) { } reader.Close(); When I setp through the code there is one item present in catalog.items, but it is empty, no name, colors or sizes. Any ideas what I need to do? Thanks

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• Are there deprecated practices for multithread and multiprocessor programming that I should no longer use?

  - by DeveloperDon

  In the early days of FORTRAN and BASIC, essentially all programs were written with GOTO statements. The result was spaghetti code and the solution was structured programming. Similarly, pointers can have difficult to control characteristics in our programs. C++ started with plenty of pointers, but use of references are recommended. Libraries like STL can reduce some of our dependency. There are also idioms to create smart pointers that have better characteristics, and some version of C++ permit references and managed code. Programming practices like inheritance and polymorphism use a lot of pointers behind the scenes (just as for, while, do structured programming generates code filled with branch instructions). Languages like Java eliminate pointers and use garbage collection to manage dynamically allocated data instead of depending on programmers to match all their new and delete statements. In my reading, I have seen examples of multi-process and multi-thread programming that don't seem to use semaphores. Do they use the same thing with different names or do they have new ways of structuring protection of resources from concurrent use? For example, a specific example of a system for multithread programming with multicore processors is OpenMP. It represents a critical region as follows, without the use of semaphores, which seem not to be included in the environment. th_id = omp_get_thread_num(); #pragma omp critical { cout << "Hello World from thread " << th_id << '\n'; } This example is an excerpt from: http://en.wikipedia.org/wiki/OpenMP Alternatively, similar protection of threads from each other using semaphores with functions wait() and signal() might look like this: wait(sem); th_id = get_thread_num(); cout << "Hello World from thread " << th_id << '\n'; signal(sem); In this example, things are pretty simple, and just a simple review is enough to show the wait() and signal() calls are matched and even with a lot of concurrency, thread safety is provided. But other algorithms are more complicated and use multiple semaphores (both binary and counting) spread across multiple functions with complex conditions that can be called by many threads. The consequences of creating deadlock or failing to make things thread safe can be hard to manage. Do these systems like OpenMP eliminate the problems with semaphores? Do they move the problem somewhere else? How do I transform my favorite semaphore using algorithm to not use semaphores anymore?

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• Windows 7 Backup - Does the "system image" include all the files on my drive?

  - by Vaccano

  I have a new Dell Laptop that I have setup the way I like it. I want to use Windows 7 to do a backup and then restore that backup on a different hard drive (solid state). When I setup the backup info (manually) for Windows 7 Backup there is a little checkbox at the the bottom that says: Include a system image of drives: RECOVERY, OS (C:) I can also select to backup all my data on the C: drive (the only hard drive I have anything on) as well as some libraries (which are on my C: drive so no point in selecting those). The question I have is, does Windows 7 Backup just somehow know what needs to be restored (ie program files and Windows and the registry ....? Or is it really making a full restorable copy of the C: drive? (If the later is true then I don't need select the C: drive to be "backed up" if I don't plan to access the files except by restoring them right? (Because the system image will already have it all.)) So, which way is it? What is saved in the System Image?

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• How to Refresh or Reset Windows 8 without the System Reserved partition?

  - by Karan

  The article Refresh and reset your PC mentions exactly what happens during the refresh and reset operations in Windows 8: Refresh The PC boots into Windows RE. Windows RE scans the hard drive for your data, settings, and apps, and puts them aside (on the same drive). Windows RE installs a fresh copy of Windows. Windows RE restores the data, settings, and apps it has set aside into the newly installed copy of Windows. The PC restarts into the newly installed copy of Windows. Reset The PC boots into the Windows Recovery Environment (Windows RE). Windows RE erases and formats the hard drive partitions on which Windows and personal data reside. Windows RE installs a fresh copy of Windows. The PC restarts into the newly installed copy of Windows. It is my understanding that Windows RE (Recovery Environment) is included as part of the System Reserved partition created by default on the first hard disk. The size of this partition has gone up to 350 MB from the 100 MB it used to be in Vista/Windows 7, no doubt as a result of adding these features. Now we have already discussed how to skip the creation of this System Reserved partition during Setup. Basically, the same techniques that used to work with Windows 7 work with Windows 8 as well. What I want to know is, what will be the exact repercussions of not having the System Reserved partition in place? I assume Troubleshoot / Advanced options should still be available as before: But what about the Troubleshoot menu itself? Will the Refresh and Reset options disappear? Will they remain but be unavailable? Or possibly they will throw an error if selected? Also, will it be possible to access and successfully execute these options if installation media is available? Anything else that might be affected?

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• Do registry issues with Win7 persist through a recovery from a system image?

  - by user59089

  So I need a bit of advice, please; here's my situation: I have 1) a system image on an a brand new external 1 TB SATA drive, that I managed to successfully capture before my 2) primary system drive went down. I realize this is a fairly simple matter of buying a new primary drive and performing the recovery to the fresh disk...however, the issue is that I believe Win7 was also having some significant issues of its own--basically, Update unable to install updates, and Backup continually ditching the auto backup schedule. I'd been trying to address those issues when my system was still working, but it's been so fruitless, I'm convinced a Win7 re-install would be best, and now I'm concerned that if I was in fact having what I believe are likely registry-related issues before, that these will persist through a recovery--would that likely be correct? I'm mainly worried about recovering my files, so if I did a full recovery from the image, should I be able to then access my individual files, and copy them manually to an external drive, so I can then do a full re-install of Win7? Sory if this seems obvious, but I've never done a recovery before and just trying to make sure there's no red flags with what I have in mind...

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• How do you recreate the System Recovery environment in Windows 7?

  - by Howiecamp

  I'm running Windows 7 Home Premium RTM (64-bit) and I want to take advantage of the system recovery tools (eg the Command Prompt) without using the Windows 7 DVD. My understanding is that this environment (WinRE) should be installed to your HDD by default as part of the Windows 7 installation. However, when I hit F8 on boot and select "Repair", I get: Windows failed to start. A recent hardware or software change might be the cause. To fix the problem... Status: 0xc000000e Info: The boot selection failed because a required device is inaccessible. The "Info" line seems like the smoking gun. My next step was to boot from the Windows 7 DVD, and choose "Repair". It indicated my Recovery Environment wasn't on the Windows 7 boot menu (perfect) and offered to fix it. I said yes and rebooted, however same issue as above. In addition, when I booted in to Windows 7 and I looked at the boot menu options, the recovery/repair option was not there. Only my Windows installation. Finally, I ran the Disk Management tool (diskmgmt.msc) and took a look at the contents of my "System Reserved" partition (which was set to "Active" as normal). It's unclear to me what the contents should look like, however it is my understanding that the WinRE environment gets installed to this partition. (As part of the above troubleshooting I followed http://superuser.com/questions/25728/how-to-fix-windows-7-boot-process which lead to http://www.sevenforums.com/tutorials/668-system-recovery-options.html).

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• Moving to .net 4 results in System.Transactions Critical: 0

  - by john

  Hi I have fully working project in .net 3.5SP1, with EF 1 ORM. I tried to upgrade to .net 4. No issue while upgrading... Then i ran the project and got a NullExecptionError, with no stack trace... and no way to debug. Looking at the output windows i can read this: System.Transactions Critical: 0 : <TraceRecord xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" Severity="Critical"><TraceIdentifier>http://msdn.microsoft.com/TraceCodes/System/ActivityTracing/2004/07/Reliability/Exception/Unhandled</TraceIdentifier><Description>Unhandled exception</Description><AppDomain>OTCSouscriptions.vshost.exe</AppDomain><Exception><ExceptionType>System.NullReferenceException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType><Message>Object reference not set to an instance of an object.</Message><StackTrace> at System.Windows.StyleHelper.GetInstanceValue(UncommonField`1 dataField, DependencyObject container, FrameworkElement feChild, FrameworkContentElement fceChild, Int32 childIndex, DependencyProperty dp, Int32 i, EffectiveValueEntry&amp;amp; entry) at System.Windows.FrameworkTemplate.ReceivePropertySet(Object targetObject, XamlMember member, Object value, DependencyObject templatedParent) at System.Windows.FrameworkTemplate.&amp;lt;&amp;gt;c__DisplayClass6.&amp;lt;LoadOptimizedTemplateContent&amp;gt;b__4(Object sender, XamlSetValueEventArgs setArgs) at System.Xaml.XamlObjectWriter.OnSetValue(Object eventSender, XamlMember member, Object value) at System.Xaml.XamlObjectWriter.Logic_ApplyPropertyValue(ObjectWriterContext ctx, XamlMember prop, Object value, Boolean onParent) at System.Xaml.XamlObjectWriter.Logic_DoAssignmentToParentProperty(ObjectWriterContext ctx) at System.Xaml.XamlObjectWriter.Logic_AssignProvidedValue(ObjectWriterContext ctx) at System.Xaml.XamlObjectWriter.WriteEndObject() at System.Xaml.XamlWriter.WriteNode(XamlReader reader) at System.Windows.FrameworkTemplate.LoadTemplateXaml(XamlReader templateReader, XamlObjectWriter currentWriter) Any help appreciated... Thanks John

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• objective c coding guidelines

  - by Chandan Shetty SP

  Is there any pdf which tells about coding guidelines in objective C. For Example... 1. Breaking the function names - checkIfHitTheTrack. 2. member variables must be like - mVariableName. 3. Giving better names to subclass - ? Please share the related links...

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