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  • Concurency problem with Isolation - read-committed

    - by Ratn Deo--Dev
    I have to write a simple demo for amount withdrawl from a joint Bank amount .Andy and Jen holds a joint bank account with number 123 . Suppose they have 100$ in their account .Jen and Andy are operating their account at the same time and both are trying to withdraw 90$ at the time being .My transaction Isolation is set to read-committed and both are able to withdraw money leaving the balance to -(minus)80$ although I have constraint that balance should never be less than 0. I am using hibernate .Is versioning only way to solve this problem or I should go for another Isolation level ?

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  • Is It Incorrect to Make Domain Objects Aware of The Data Access Layer?

    - by Noah Goodrich
    I am currently working on rewriting an application to use Data Mappers that completely abstract the database from the Domain layer. However, I am now wondering which is the better approach to handling relationships between Domain objects: Call the necessary find() method from the related data mapper directly within the domain object Write the relationship logic into the native data mapper (which is what the examples tend to do in PoEAA) and then call the native data mapper function within the domain object. Either it seems to me that in order to preserve the 'Fat Model, Skinny Controller' mantra, the domain objects have to be aware of the data mappers (whether it be their own or that they have access to the other mappers in the system). Additionally it seems that Option 2 unnecessarily complicates the data access layer as it creates table access logic across multiple data mappers instead of confining it to a single data mapper. So, is it incorrect to make the domain objects aware of the related data mappers and to call data mapper functions directly from the domain objects? Update: These are the only two solutions that I can envision to handle the issue of relations between domain objects. Any example showing a better method would be welcome.

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  • What is SSIS order of data transformation component method calls

    - by Ron Ruble
    I am working on a custom data transformation component. I'm using NUnit and NMock2 to test as I code. Testing and getting the custom UI and other features right is a huge pain, in part because I can't find any documentation about the order in which SSIS invokes methods on the component at design time as well as runtime. I can correct the issues readily enough, but it's tedious and time consuming to unregister the old version, register the new version, fire up the test ssis package, try to display the UI, get an obscure error message, backtrace it, modify the component and continue. One of the big issues involves the UI component needing access to the componentmetadata and buffermanager properties of the component at design time, and what I need to provide for to support properties that won't be initialized until after the user enters them in the UI. I can work through it; but if someone knows of some docs or tips that would speed me up, I'd greatly appreciate it. The samples I've found havn't been much use; they seem to be directed to showing off cool stuff (Twitter, weather.com) rather than actual work. Thanks in advance.

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  • Pattern for managing reference count and object life

    - by Gopalakrishnan Subramani
    We have a serial port which is connected to hundreds of physical devices on the same wire. We have protocols like Modbus and Hart to handle the request and response between the application and devices. The question is related to managing the reference count of the channel. When no device is using the channel, the channel should be closed. public class SerialPortChannel { int refCount = 0; public void AddReference() { refCount++; } public void ReleaseReference() { refCount--; if (refCount <= 0) this.ReleasePort(); //This close the serial port } } For each device connected, we create a object for the device like device = new Device(); device.Attach(channel); //this calls channel.AddReference() When the device disconnect, device.Detach(channel); //this calls channel.ReleaseReference() I am not convinced by the reference count model. Are there any better way to handle this problem in .NET World?

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  • How can i return abstract class from any factory?

    - by programmerist
    using System; using System.Collections.Generic; using System.Linq; using System.Web; namespace EfTestFactory { public abstract class _Company { public abstract List<Personel> GetPersonel(); public abstract List<Prim> GetPrim(); public abstract List<Finans> GetFinans(); } public abstract class _Radyoloji { public abstract List<string> GetRadyoloji(); } public abstract class _Satis { public abstract List<string> GetSatis(); } public abstract class _Muayene { public abstract List<string> GetMuayene(); } public class Company : _Company { public override List<Personel> GetPersonel() { throw new NotImplementedException(); } public override List<Prim> GetPrim() { throw new NotImplementedException(); } public override List<Finans> GetFinans() { throw new NotImplementedException(); } } public class Radyoloji : _Radyoloji { public override List<string> GetRadyoloji() { throw new NotImplementedException(); } } public class Satis : _Satis { public override List<string> GetSatis() { throw new NotImplementedException(); } } public class Muayene : _Muayene { public override List<string> GetMuayene() { throw new NotImplementedException(); } } public class GenoTipController { public object CreateByEnum(DataModelType modeltype) { string enumText = modeltype.ToString(); // will return for example "Company" Type classType = Type.GetType(enumText); // the Type for Company class object t = Activator.CreateInstance(classType); // create an instance of Company class return t; } } public class AntsController { static Dictionary<DataModelType, Func<object>> s_creators = new Dictionary<DataModelType, Func<object>>() { { DataModelType.Radyoloji, () => new _Radyoloji() }, { DataModelType.Company, () => new _Company() }, { DataModelType.Muayene, () => new _Muayene() }, { DataModelType.Satis, () => new _Satis() }, }; public object CreateByEnum(DataModelType modeltype) { return s_creators[modeltype](); } } public class CompanyView { public static List<Personel> GetPersonel() { GenoTipController controller = new GenoTipController(); _Company company = controller.CreateByEnum(DataModelType.Company) as _Company; return company.GetPersonel(); } } public enum DataModelType { Radyoloji, Satis, Muayene, Company } } if i write above codes i see some error: Cannot create an instance of abstract class or interface 'EfTestFactory_Company'How can i solve it? Look please below pic.

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  • Object Oriented Database - why most of the companies do not use them

    - by GigaPr
    Hi, I am pretty new to programming(just finished University). I have been thought in the last 4 years about Object Oriented development and the numerous advantages of this approach. My question is Isn't it easier to use a pure Object Oriented database in development applications? Why Object Oriented database are not as much diffuse as relational? From my point of view makes sense to use OO database, the latter will avoid the numerous construction necessary for the mapping of complex objects on the tables.

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  • Passing data structures to different threads

    - by Robb
    I have an application that will be spawning multiple threads. However, I feel there might be an issue with threads accessing data that they shouldn't be. I'm relatively new to threading so bare with me. Here is the structure of the threaded application (sorry for the crudeness): MainThread / \ / \ / \ Thread A Thread B / \ / \ / \ / \ / \ / \ Thread A_1 Thread A_2 Thread B_1 Thread B_2 Under each lettered thread (which could be many), there will only be two threads and they are fired of sequentially. The issue i'm having is I'm not entirely sure how to pass in a datastructure into these threads. So, the datastructure is created in MainThread, will be modified in the lettered thread (Thread A, etc) specific to that thread and then a member variable from that datastructure is sent to Letter_Numbered threads. Currently, the lettered thread class has a member variable and when the class is constructed, the datastructure from mainthread is passed in by reference, invoking the copy constructor so the lettered thread has it's own copy to play with. The lettered_numbered thread simply takes in a string variable from the data structure within the lettered thread. My question is, is this accceptable? Is there a much better way to ensure each lettered thread gets its own data structure to play with? Sorry for the somewhat poor explanation, please leave comments and i'll try to clarify.

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  • How to make use of c++ xpcom component from javascript xpcom component.

    - by Prashant
    I have developed a xpcom component using c++. I have GetHWND() method in my component. I have also developed another xpcom component using javascript. I want to make use of GetHWND function in javascript xpcom component. I am using following code to do so. netscape.security.PrivilegeManager.enablePrivilege("UniversalBrowserRead"); netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect"); var myComponent = Components.classes['@dougt/WebLock'].createInstance(Components.interfaces.IWebLock); myComponent = myComponent.QueryInterface(Components.interfaces.IWebLock); var res = myComponent.GetHWND(mainWindow.content.document); But it is giving error as "ReferenceError: netscape is not defined". I did google search but did not find the solution to it. I am using Mozilla Firefox and I want it to get worked for the same. Please help me to come out of this problem. Thanks in advance.

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  • AIR:- Desktop Application related to Window Component (Need some work around)

    - by Mahesh Parate
    Create custom component which contains Combobox and Datagrid. Application conations two button 1) Same Window and 2) New Window. (Label of two button) When you click on “Same Window” button your custom component should get added dynamically in your application. And when you click on “New Window” button your custom component should get open in different window (it should get shifted from application and should appear in Window component). Issue faced:- Clicking on Combobox, list is not getting open as change event doesn’t get fired in Native Window as it looses reference from main application. Issue with DataGrid in Native window (AIR). • DataGridEvent.COLUMN_STRETCH event get affected if try to open datagrid in Native Window. • DataGridEvent get fired but takes long time or even stuck while column stretch Note: Application is an Desktop Application. Only one instance is created in Application for your custom component to preserve current state on your custom component it can be Style, data, or other subcomponent state of your custom component (as above mentioned 2 component are just sample). Please find sample code below:- DataGridStretchIssue.mxml:- < ?xml version="1.0" encoding="utf-8"? < mx:WindowedApplication xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" xmlns:local="*" width="800" height="500" < mx:Script < ![CDATA[ import mx.events.FlexEvent; import mx.core.Window; private var dgComp:DataGridComp = new DataGridComp(); private var win:Window; private function clickHandler(event:Event):void{ dgComp.percentWidth = 100; dgComp.percentHeight = 100; dgComp.x = 50; dgComp.y = 100; if(win){ win.close(); } this.addChild(dgComp); } private function openClickHandler(event:MouseEvent):void{ dgComp.x = 50; dgComp.y = 100; win = new Window();; win.width = 800; win.height = 500; win.addChild(dgComp); dgComp.percentWidth = 100; dgComp.percentHeight = 100; dgComp.x = 50; dgComp.y = 100; win.open(true) } ]]> < /mx:Script < mx:HBox <mx:Button id="btnID" click="clickHandler(event)" label="Same Window"/> <mx:Button id="btnIDOpen" click="openClickHandler(event)" label="New Window"/> < /mx:HBox < /mx:WindowedApplication DataGridComp.mxml < ?xml version="1.0" encoding="utf-8"? < mx:Canvas xmlns:mx="http://www.adobe.com/2006/mxml" width="100%" height="100%" <mx:Script> <![CDATA[ import mx.events.DataGridEvent; import mx.collections.ArrayCollection; [Bindable] public var cards:ArrayCollection = new ArrayCollection( [ {label:"Visa", data:1}, {label:"MasterCard", data:2}, {label:"American Express", data:3} ]); private function stretchFn(event:DataGridEvent):void{ trace("--- Stretched---") } ]]> </mx:Script> <mx:HBox> <mx:ComboBox dataProvider="{cards}" width="150"/> <mx:DataGrid columnStretch="stretchFn(event)" > <mx:ArrayCollection> <mx:Object> <mx:Artist>Pavement</mx:Artist> <mx:Price>11.99</mx:Price> <mx:Album>Slanted and Enchanted</mx:Album> </mx:Object> <mx:Object> <mx:Artist>Pavement</mx:Artist> <mx:Album>Brighten the Corners</mx:Album> <mx:Price>11.99</mx:Price> </mx:Object> </mx:ArrayCollection> </mx:DataGrid> </mx:HBox> < /mx:Canvas Can any one suggest me some work around to make my code workable... :)

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  • hibernate - lazy init joined component

    - by robinmag
    I used the mapping solution from this question to have a joined component. But it make hibernate trigger join query to obtain the component event i use fetch="select" in <join> Please tell me how can i make the joined component lazy init. Thank you

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  • Hierarchy / Flyweight / Instancing Problem in Python

    - by Dan
    Here is the problem I am trying to solve, (I have simplified the actual problem, but this should give you all the relevant information). I have a hierarchy like so: 1.A 1.B 1.C 2.A 3.D 4.B 5.F (This is hard to illustrate - each number is the parent, each letter is the child). Creating an instance of the 'letter' objects is expensive (IO, database costs, etc), so should only be done once. The hierarchy needs to be easy to navigate. Children in the hierarchy need to have just one parent. Modifying the contents of the letter objects should be possible directly from the objects in the hierarchy. There needs to be a central store containing all of the 'letter' objects (and only those in the hierarchy). 'letter' and 'number' objects need to be possible to create from a constructor (such as Letter(**kwargs) ). It is perfectably acceptable to expect that when a letter changes from the hierarchy, all other letters will respect the same change. Hope this isn't too abstract to illustrate the problem. What would be the best way of solving this? (Then I'll post my solution) Here's an example script: one = Number('one') a = Letter('a') one.addChild(a) two = Number('two') a = Letter('a') two.addChild(a) for child in one: child.method1() for child in two: print '%s' % child.method2()

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  • Conventions for the behavior of double or triple "click to select text" features?

    - by John Sullivan
    Almost any mature program that involves text implements "double click to select the word" and, in some cases, "triple click to select additional stuff like an entire line" as a feature. I find these features useful but they are often inconsistent between programs. Example - some programs' double clicks do not select the ending space after a word, but most do. Some recognize the - character as the end of a word, others do not. SO likes to select the entire paragraph as I write this post when I triple click it, VS web developer 2005 has no triple click support, and ultra-edit 32 will select one line upon triple clicking. We could come up with innumerable inconsistencies about how double and triple click pattern matching is implemented across programs. I am concerned about how to implement this behavior in my program if nobody else has achieved a convention about how the pattern matching should work. My question is, does a convention (conventions? maybe an MS or Linux convention?) exist that dictates how these features are supposed to behave to the end user? What, if any, are they?

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  • Can a binary tree or tree be always represented in a Database as 1 table and self-referencing?

    - by Jian Lin
    I didn't feel this rule before, but it seems that a binary tree or any tree (each node can have many children but children cannot point back to any parent), then this data structure can be represented as 1 table in a database, with each row having an ID for itself and a parentID that points back to the parent node. That is in fact the classical Employee - Manager diagram: one boss can have many people under him... and each person can have n people under him, etc. This is a tree structure and is represented in database books as a common example as a single table Employee.

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  • JTextPane insert component, faulty vertical alignment

    - by John O
    I have a JTextPane, into which I need to insert a JComponent. I'm using JTextPane.insertComponent(Component). The item is indeed inserted, but the vertical positioning is too high. Instead of having the bottom of the component aligned with the baseline of the current line of text, the component is way above that position, blocking out/over-painting lines of text appearing above. I have tried calling setAlignmentY(float) with various values, on both the inserted component and the JTextPane, but it doesn't affect the behavior at all. My guess: there seems to be some state inside my JTextPane or its Document that I need to be changing. But I don't know what it is. John

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  • How expose the properties of an component created in an activex form

    - by Salvador
    You can publish the properties of an control that is inside a activex form? example I have a form with an TAdoconnection component, I wish the properties of this component can be modified by the user when he loads my activex control. UPDATE @TOndrej gives me a very nice sample, but this sample only works for components derived from an activex control, how can accomplish this same efffect with an VCL component like an Timage or TMemo? is possible publish all the properties without rewrite each property to expose manually?

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  • Some basic UML questions

    - by devoured elysium
    What does it mean when you have something as the following picture? Each Customer has none, one or more Orders while each Order has only one Customer? And in relationship to the following one: What does the black diamond mean in this context? How is that black diamond called? Thanks

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  • .net component installer for COM interop

    - by daemonkid
    I have a .net component that will be called by unmanaged code. I want to create an installer for the .net component that will in one step.. -install it to the desired directory -generate the tlb file -run the regasm command The deployers of this component dont have knowledge of the .net framework. Any ideas? Thanks.

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  • Simply doing modelType.ToString() isn't sufficient, How can i use it via Activator.CreateInstance?

    - by programmerist
    public class MyController { public object CreateByEnum(DataModelType modeltype) { string enumText = modeltype.ToString(); // will return for example "Company" Type classType = Type.GetType(enumText); // the Type for Company class object t = Activator.CreateInstance(classType); // create an instance of Company class return t; } } public class CompanyView { public static List<Personel> GetPersonel() { MyController controller = new MyController(); _Company company = controller.CreateByEnum(DataModelType.Company) as _Company; return company.GetPersonel(); } } public enum DataModelType { xyz, klm, tucyz, Company } Yes, I agree Activator.CreateInstance() is very useful. Unfortunately, I need to pass in the correct type. That means building the correct string to pass to Type.GetType(). If I trace through the call to Controller.CreatebyEnum() in the code I posted above, simply doing modelType.ToString() isn't sufficient, even for the case of DataModelType.Company. My solution'll be maintenance bottleneck. What would be better is something that takes the results of modelType.ToString() and then recursively searches through all the types found in all the assemblies loaded in the current AppDomain. According to MSDN, Type.GetType() only searches the current calling assembly, and mscorlib.dll. How can i do that? . i need best performance?

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  • FLEX components: updating import statements to move the component into another folder

    - by Patrick
    hi, I've just imported a Flex component into my project. I have a theory question about importing. all the imports statements in the component source files started with "com.subFolder.etc", but I have preferred to move the component folders into "componentName" and to replace all import statements as "componentName.com.subFolder.etc" Is this ok ? Everything works perfectly, but I was wondering if the method is correct. thanks

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  • Designing a class in such a way that it doesn't become a "God object"

    - by devoured elysium
    I'm designing an application that will allow me to draw some functions on a graphic. Each function will be drawn from a set of points that I will pass to this graphic class. There are different kinds of points, all inheriting from a MyPoint class. For some kind of points it will be just printing them on the screen as they are, others can be ignored, others added, so there is some kind of logic associated to them that can get complex. How to actually draw the graphic is not the main issue here. What bothers me is how to make the code logic such that this GraphicMaker class doesn't become the so called God-Object. It would be easy to make something like this: class GraphicMaker { ArrayList<Point> points = new ArrayList<Point>(); public void AddPoint(Point point) { points.add(point); } public void DoDrawing() { foreach (Point point in points) { if (point is PointA) { //some logic here else if (point is PointXYZ) { //...etc } } } } How would you do something like this? I have a feeling the correct way would be to put the drawing logic on each Point object (so each child class from Point would know how to draw itself) but two problems arise: There will be kinds of points that need to know all the other points that exist in the GraphicObject class to know how to draw themselves. I can make a lot of the methods/properties from the Graphic class public, so that all the points have a reference to the Graphic class and can make all their logic as they want, but isn't that a big price to pay for not wanting to have a God class?

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