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  • Whats the best way to design this database scenario?

    - by ankimal
    I want to setup 2 MySQL databases which differ in schema in that, one is normalized and the other is flat for quicker reads and writes. The information being stored in both DBs is the same, but the representation is obviously different owing to the different design approaches. I need to find a robust solution to sync information in real time from my normalized version to my flatter version.

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  • What method do you use to identify the Aggregate Roots in Domain Drive Design?

    - by Robert
    When applying Domain Driven Design to a project, how do you identify the Aggregate Roots? For example, in a standard E-Commerce website, you might say that the Order is one, and the User is the other. But what if your Users belong to a Company? Does that make your Company the aggregate root? I'm interested in hearing people's approaches to working out the Aggregate roots, and how to identify poorly chosen aggregate roots.

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  • About Data Objects and DAO Design when using Hibernate

    - by X. Ma
    I'm hesitating between two designs of a database project using Hibernate. Design #1. (1) Create a general data provider interface, including a set of DAO interfaces and general data container classes. It hides the underneath implementation. A data provider implementation could access data in database, or an XML file, or a service, or something else. The user of a data provider does not to know about it. (2) Create a database library with Hibernate. This library implements the data provider interface in (1). The bad thing about Design #1 is that in order to hide the implementation details, I need to create two sets of data container classes. One in the general data provider interface - let's call them DPI-Objects, the other set is used in the database library, exclusively for entity/attribute mapping in Hibernate - let's call them H-Objects. In the DAO implementation, I need to read data from database to create H-Objects (via Hibernate) and then convert H-Objects into DPI-Objects. Design #2. Do not create a general data provider interface. Expose H-Objects directly to components that use the database lib. So the user of the database library needs to be aware of Hibernate. I like design #1 more, but I don't want to create two sets of data container classes. Is that the right way to hide H-Objects and other Hibernate implementation details from the user who uses the database-based data provider? Are there any drawbacks of Design #2? I will not implement other data provider in the new future, so should I just forget about the data provider interface and use Design #2? What do you think about this? Thanks for your time!

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  • WpfToolkit DataGrid does not work in Windows Phone 7

    - by Igor Zevaka
    I am trying to use WpfToolkit DataGrid in Windows Phone 7 project (Silverligt 4) and it's not working. Here is the XAML: <UserControl x:Class="SilverlightControls.Grid" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" xmlns:wtk="clr-namespace:Microsoft.Windows.Controls;assembly=WPFToolkit" d:DesignHeight="480" d:DesignWidth="480"> <Grid x:Name="LayoutRoot" Background="#FF1F1F1F" Width="960"> <Grid x:Name="TitleGrid"> <TextBlock Text="{Binding Title}" Style="{StaticResource PhoneTextPageTitle2Style}"/> </Grid> <wtk:DataGrid> </wtk:DataGrid> </Grid> </UserControl> The project compiles fine but crashes at runtime trying to load this control. The best clue I got so far is from Visual Studio Designer. Once I add wtk:DataGrid to the control the visual designer does not load and below is the exception it displays. Could it be that WpfToolkit relies on PresentationFramework.dll and it's not available in SL4? System.Reflection.Adds.UnresolvedAssemblyException Type universe cannot resolve assembly: PresentationFramework, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35. at System.Reflection.Adds.AssemblyProxy.GetResolvedAssembly() at System.Reflection.Adds.AssemblyProxy.get_FullName() at Microsoft.Windows.Design.Metadata.ReflectionMetadataContext.PrepareAttributes(Reflectable`1 reflectableAssembly) at Microsoft.Windows.Design.Metadata.ReflectionMetadataContext.PrepareAttributes(Reflectable`1 reflectableType) at MS.Internal.Metadata.ClrType.GetAttributes[T](ReflectionMetadataContext context, IReflectable`1 member, ITypeMetadata attributeType, Boolean merge, AttributeMergeCache& cache) at MS.Internal.Metadata.ClrMember`1.GetLocalAttributes(ITypeMetadata attributeType) at MS.Internal.Design.Metadata.Xaml.XamlType.GetSpecialProperty(Int32 idx, PropertyIdentifier pid) at MS.Internal.Design.Metadata.Xaml.XamlType.get_ContentProperty() at Microsoft.Windows.Design.Metadata.Xaml.XamlExtensionImplementations.GetContentProperty(ITypeMetadata sourceType) at Microsoft.Windows.Design.Metadata.Xaml.XamlExtensions.GetContentProperty(ITypeMetadata source) at MS.Internal.Design.Metadata.ReflectionTypeNode.get_ContentProperty() at MS.Internal.Design.Markup.XmlElement.CalcChildWhitespaceImportant(XamlElement element) at MS.Internal.Design.Markup.XmlElement.ConvertChildrenToXaml(XamlElement result, PrefixScope scope, IParseContext context, IMarkupSourceProvider provider, Boolean childrenAsString) at MS.Internal.Design.Markup.XmlElement.ConvertToXaml(XamlElement parent, PrefixScope parentScope, IParseContext context, IMarkupSourceProvider provider) at MS.Internal.Design.Markup.XmlElement.ConvertChildrenToXaml(XamlElement result, PrefixScope scope, IParseContext context, IMarkupSourceProvider provider, Boolean childrenAsString) at MS.Internal.Design.Markup.XmlElement.ConvertToXaml(XamlElement parent, PrefixScope parentScope, IParseContext context, IMarkupSourceProvider provider) at MS.Internal.Design.DocumentModel.DocumentTrees.Markup.XamlSourceDocument.ParseElementFromSkeleton(XamlParseContext context, SkeletonNode node, XamlElement parent, Boolean fullElement) at MS.Internal.Design.DocumentModel.DocumentTrees.Markup.XamlSourceDocument.UpdateSkeleton(IDamageListener listener) at Microsoft.Windows.Design.DocumentModel.Trees.MarkupDocumentTreeManager.Update() at Microsoft.Windows.Design.DocumentModel.MarkupProducer.Update() at Microsoft.Windows.Design.DocumentModel.MarkupProducer.HandleMessage(DocumentTreeCoordinator sender, MessageKey key, MessageArguments args) at Microsoft.Windows.Design.DocumentModel.MarkupProducer.Microsoft.Windows.Design.DocumentModel.IDocumentTreeConsumer.HandleMessage(DocumentTreeCoordinator sender, MessageKey key, MessageArguments args) at Microsoft.Windows.Design.DocumentModel.DocumentTreeCoordinator.SendMessage[T](MessageKey`1 key, T args, Boolean isPrivateMessage) at Microsoft.Windows.Design.DocumentModel.DocumentTreeCoordinator.QueuedMessage`1.Microsoft.Windows.Design.DocumentModel.IQueuedMessage.Invoke() at Microsoft.Windows.Design.DocumentModel.DocumentTreeCoordinator.ProcessQueuedMessages(Object state) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)

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  • Do I need to use any other attributes other than CssClassProperty to enabled design-time support?

    - by keith
    Hi, I'm trying to provide the same design-time support that the CssClass provides on some custom properties of a server control. The documentation suggests that decorating the property with the CssClassProperty is all that's required. [CssClassProperty] public string SomeOtherCssClass{get;set;} This has no effect, in vs2008 or vs2010. I've looked at the WebControl class using reflector and implemented all the attributes, and every combination thereof, to my property and still no class dropdown. Some blog posts suggest that the use of the Editor attribute but a) there's not mention of it in the documentation and b) none of editors which are remotely related to css classes have any effect either. Am I missing something to enable this feature? Thanks in advance, Keith.

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  • is it wasteful/bad design to use a vector/list where in most instances it will only have one element

    - by lucid
    is it wasteful/bad design to use a vector/list where in most instances it will only have one element? example: class dragon { ArrayList<head> = new ArrayList<head> Heads; tail Tail = new tail(); body Body = new body(); dragon() { theHead=new head(); Heads.add(theHead); } void nod() { for (int i=0;i<Heads.size();i++) { heads.get(i).GoUpAndDown(); } } } class firedragon extends dragon { } class icedragon extends dragon { } class lightningdragon extends dragon { } // 10 other one-headed dragon declarations here class hydra extends dragon { hydra() { anotherHead=new head(); for (int i=0;i<2;i++) { Heads.add(anotherHead); } } } class superhydra extends dragon { superhydra() { anotherHead=new head(); for (int i=0;i<4;i++) { Heads.add(anotherHead); } } }

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  • can we have one attribute with multiple values in an eav design?

    - by Shekhar
    i am doing a database design using EAV. I am facing an issue when i try to model an entity with attribute having multiple values? For example Entity id | name | description 1 | configuration1 | configuration1 Attribute id | entityId | name | type 1 | 1 |att1 | string 2 | 1 |att2 | int 3 |1 | att3 | List (How will i model this?) Value id | attributeId | value 1 | 1 | a 2 | 2 | 1 3 | 3 | b 4 | 3 | c 5 | 3 |d Is this the correct way to handle list of values? Please provide any helpful link to model this? Thanks Shekhar

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  • Singleton class design in C#, are these two classes equivalent?

    - by Oskar
    I was reading up on singleton class design in C# on this great resource and decided to go with alternative 4: public sealed class Singleton1 { static readonly Singleton1 _instance = new Singleton1(); static Singleton1() { } Singleton1() { } public static Singleton1 Instance { get { return _instance; } } } Now I wonder if this can be rewritten using auto properties like this? public sealed class Singleton2 { static Singleton2() { Instance = new Singleton2(); } Singleton2() { } public static Singleton2 Instance { get; private set; } } If its only a matter of readability I definitely prefer the second version, but I want to get it right.

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  • How can I avoid properties being reset at design-time in tightly bound user controls?

    - by David Anderson
    I have UserControl 'A' with a label, and this property: /// <summary> /// Gets or Sets the text of the control /// </summary> [ Browsable(true), EditorBrowsable(EditorBrowsableState.Always), Category("Appearance") ] public override string Text { get { return uxLabel.Text; } set { uxLabel.Text = value; } } I then have UserControl 'B' which has UserControl 'A' on it, and I set the Text Property to "My Example Label" in the designer. Then, I have my MainForm, which has UserControl 'B' on it. Each time I do a build or run, the Text property of UserControl 'A' is reset to its default value. I suppose this is because since I am doing a rebuild, it rebuilds both UserControl 'A' and 'B', thus causing the problem. How can I go about a better approach to design pattern to avoid this type of behavior when working with tightly bound controls and forms in a application?

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  • Is using a FSM a good design for general text parsing?

    - by eSKay
    I am reading a file that is filled with hex numbers. I have to identify a particular pattern, say "aaad" (without quotes) from it. Every time I see the pattern, I generate some data to some other file. This would be a very common case in designing programs - parsing and looking for a particular pattern. I have designed it as a Finite State Machine and structured structured it in C using switch-case to change states. This was the first implementation that occured to me. DESIGN: Are there some better designs possible? IMPLEMENTATION: Do you see some problems with using a switch case as I mentioned?

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  • how can I design a good architechture for a Transaction Processing System?

    - by ghedas
    I have a project that must design an architecture for it. This project is a something like a Transaction Processing system and I need to know something like this: when and where I must use synchronous and asynchronous relations between its components? If always I use synchronous relations, the amount of messages maybe become exceeded and makes problem for TP system, and on the other hand synchronous relations make lots of delay, I think a mixture of them is required! If other parameters required to considering please help me! the most nonfunctional requirements of this project are performance and availability of it. I need useful materials and suggestions for it.

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  • Stream classes ... design, pattern for creating views over streams

    - by ToxicAvenger
    A question regarding the design of stream classes - I need a pattern to create independent views over a single stream instance (in my case for reading). A view would be a consecutive part of the stream. The problem I have with the stream classes is that the state (reading or writing) is coupled with the underlying data/storage. So if I need to partition a stream into different segments (whether segments overlap or not doesn't matter), I cannot easily create views over the stream, the views would store start and end position. Because reading from a view - which would translate to reading from the underlying stream adjusted based on the start/end positions - would change the state of the underlying stream instance. So what I could do is take a read on a view instance, adjust the Position of the stream, read the chunks I need. But I cannot do that concurrently. Why is it designed in such a way, and what kind of pattern could I implement to create independet views over a single stream instance which would allow to read/write independently (and concurrently)?

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  • ASP.NET (AJAX) UI Design Tools for Artistically Challenged?

    - by davemackey
    I'm building an application but I'm artistically challenged and I'd rather not spend my time writing widgets (e.g. ability to collapse/expand/close/drag-drop) if there is already controls available. I've worked with the Microsoft AJAX Control Toolkit - but these tools still require a lot of work to get a working widget (which in my case, won't look too pretty). The CollapsiblePanel is pretty nice - but then you have to program in the minimize button, close button, maximize button, etc. Looking for suggestions that will help me design better UI faster...

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  • What problems do you find with this view on domain-driven design?

    - by Bozho
    I just wrote a long (and messy) blogpost about my view on domain-driven design at present day, with frameworks like spring and hibernate massively in use. I'd ask you to spot any problems with my views on the matter - why this won't work, why it isn't giving the benefits of DDD, why it is not a good idea in general. The blogpost is here (I don't think I need to copy-paste it on SO - if you think I should, tell me). I know the question is subjective, but it is aimed at gathering the most predominant opinions. (I'm tagging Java, since the frameworks discussed are Java frameworks)

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  • Is there a design pattern for injecting methods into a class?

    - by glenn I.
    I have a set of classes that work together (I'm coding in javascript). There is one parent class and a number of child classes that are instantiated by the parent class. I have a number of clients of these classes that each need to add on one more methods to the parent or child classes. Rather than having each client inherit from these classes, which is doable but messy because of the child classes, I am having these clients pass functions into the parent class when they instantiate the main class. The main class creates the methods dynamically and the clients can call the methods like they were there all along. My questions are: is this a sensible thing to do? what would the design pattern be for what I am doing?

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  • How can I handle multiple views of a data object? Which design pattern is acceptable?

    - by tranquil.byte
    I have a person object. class Person { private $name; ... } I need to be able to change how they are displayed on the front-end ( visitors have control ). They can choose list view, grid view, photo view for example. class PersonDisplay { public function displayList() { // Query database // Output html to display in list mode } public function displayPhoto() { // Query database // Output html to display in photo mode } } Is this an acceptable way to handle the presentation of the items on the front-end or is there a specific design pattern I should be researching to help me with this task? Does anyone have any suggestions or ideas where this could go wrong or if this could potentially make maintenance a nightmare? The Person object was just an example very similiar to what I am using.

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