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  • Building a professional company website

    - by Sphynx
    Hi fellows, I want to create a professional website for my company. I'm not a designer. I know some html/css, but I don't have much experience making up advanced pages and layouts. I'd expect public area, with various articles, and a "customer zone", accessible via username and password, where clients will be able to track their orders and download files. It needs to look very modern. I don't want to use website templates, because they're too simple. I know some Wordpress, but that's mostly for blogs, and anyways you need to find a right theme besides the CMS itself... Is there any alternative solution, some kind of framework for building such portals? Preferably a system that doesn't require designer skills. Thanks!

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  • translating specifications into query predicates

    - by Jeroen
    I'm trying to find a nice and elegant way to query database content based on DDD "specifications". In domain driven design, a specification is used to check if some object, also known as the candidate, is compliant to a (domain specific) requirement. For example, the specification 'IsTaskDone' goes like: class IsTaskDone extends Specification<Task> { boolean isSatisfiedBy(Task candidate) { return candidate.isDone(); } } The above specification can be used for many purposes, e.g. it can be used to validate if a task has been completed, or to filter all completed tasks from a collection. However, I want to re-use this, nice, domain related specification to query on the database. Of course, the easiest solution would be to retrieve all entities of our desired type from the database, and filter that list in-memory by looping and removing non-matching entities. But clearly that would not be optimal for performance, especially when the entity count in our db increases. Proposal So my idea is to create a 'ConversionManager' that translates my specification into a persistence technique specific criteria, think of the JPA predicate class. The services looks as follows: public interface JpaSpecificationConversionManager { <T> Predicate getPredicateFor(Specification<T> specification, Root<T> root, CriteriaQuery<?> cq, CriteriaBuilder cb); JpaSpecificationConversionManager registerConverter(JpaSpecificationConverter<?, ?> converter); } By using our manager, the users can register their own conversion logic, isolating the domain related specification from persistence specific logic. To minimize the configuration of our manager, I want to use annotations on my converter classes, allowing the manager to automatically register those converters. JPA repository implementations could then use my manager, via dependency injection, to offer a find by specification method. Providing a find by specification should drastically reduce the number of methods on our repository interface. In theory, this all sounds decent, but I feel like I'm missing something critical. What do you guys think of my proposal, does it comply to the DDD way of thinking? Or is there already a framework that does something identical to what I just described?

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  • strategy for observer pattern?

    - by fayer
    I want to use observer pattern for a logging system. We have got logObservers and logObservables. The class that will have to log something will implement iLogObservable and include these methods: private $logObservers = array(); public function addLogObserver($logObserver) { $this->logObservers[] = $logObserver; } public function removeLogObserver($logObserver) { $this->logObservers[] = $logObserver; } public function write($type, $message) { foreach($this->logObservers as $logObserver) { $logObserver->log($level, $message); ; } } Then I noticed, that a lot of classes that will use logging will have these methods and I have to copy paste. So isn't it better to have these methods in a class I call LogObservable or just Log and then use strategy (instantiate this class inside all classes that will have to log). When I change the methods in Log, all logObservables will be affected. However, I have not seen anyone use observer pattern with strategy pattern yet, but it seems to be very efficient and remove the duplications. What do you think?

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  • System.Timers.Timer leaking due to "direct delegate roots"

    - by alimbada
    Apologies for the rather verbose and long-winded post, but this problem's been perplexing me for a few weeks now so I'm posting as much information as I can in order to get this resolved quickly. We have a WPF UserControl which is being loaded by a 3rd party app. The 3rd party app is a presentation application which loads and unloads controls on a schedule defined by an XML file which is downloaded from a server. Our control, when it is loaded into the application makes a web request to a web service and uses the data from the response to display some information. We're using an MVVM architecture for the control. The entry point of the control is a method that is implementing an interface exposed by the main app and this is where the control's configuration is set up. This is also where I set the DataContext of our control to our MainViewModel. The MainViewModel has two other view models as properties and the main UserControl has two child controls. Depending on the data received from the web service, the main UserControl decides which child control to display, e.g. if there is a HTTP error or the data received is not valid, then display child control A, otherwise display child control B. As you'd expect, these two child controls bind two separate view models each of which is a property of MainViewModel. Now child control B (which is displayed when the data is valid) has a RefreshService property/field. RefreshService is an object that is responsible for updating the model in a number of ways and contains 4 System.Timers.Timers; a _modelRefreshTimer a _viewRefreshTimer a _pageSwitchTimer a _retryFeedRetrievalOnErrorTimer (this is only enabled when something goes wrong with retrieving data). I should mention at this point that there are two types of data; the first changes every minute, the second changes every few hours. The controls' configuration decides which type we are using/displaying. If data is of the first type then we update the model quite frequently (every 30 seconds) using the _modelRefreshTimer's events. If the data is of the second type then we update the model after a longer interval. However, the view still needs to be refreshed every 30 seconds as stale data needs to be removed from the view (hence the _viewRefreshTimer). The control also paginates the data so we can see more than we can fit on the display area. This works by breaking the data up into Lists and switching the CurrentPage (which is a List) property of the view model to the right List. This is done by handling the _pageSwitchTimer's Elapsed event. Now the problem My problem is that the control, when removed from the visual tree doesn't dispose of it's timers. This was first noticed when we started getting an unusually high number of requests on the web server end very soon after deploying this control and found that requests were being made at least once a second! We found that the timers were living on and not stopping hours after the control had been removed from view and that the more timers there were the more requests piled up at the web server. My first solution was to implement IDisposable for the RefreshService and do some clean up when the control's UnLoaded event was fired. Within the RefreshServices Dispose method I've set Enabled to false for all the timers, then used the Stop() method on all of them. I've then called Dispose() too and set them to null. None of this worked. After some reading around I found that event handlers may hold references to Timers and prevent them from being disposed and collected. After some more reading and researching I found that the best way around this was to use the Weak Event Pattern. Using this blog and this blog I've managed to work around the shortcomings in the Weak Event pattern. However, none of this solves the problem. Timers are still not being disabled or stopped (let alone disposed) and web requests are continuing to build up. Mem Profiler tells me that "This type has N instances that are directly rooted by a delegate. This can indicate the delegate has not been properly removed" (where N is the number of instances). As far as I can tell though, all listeners of the Elapsed event for the timers are being removed during the cleanup so I can't understand why the timers continue to run. Thanks for reading. Eagerly awaiting your suggestions/comments/solutions (if you got this far :-p)

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  • Foreign key pointing to different tables

    - by Álvaro G. Vicario
    I'm implementing a table per subclass design I discussed in a previous question. It's a product database where products can have very different attributes depending on their type, but attributes are fixed for each type and types are not manageable at all. I have a master table that holds common attributes: product_type ============ product_type_id INT product_type_name VARCHAR E.g.: 1 'Magazine' 2 'Web site' product ======= product_id INT product_name VARCHAR product_type_id INT -> Foreign key to product_type.product_type_id valid_since DATETIME valid_to DATETIME E.g. 1 'Foo Magazine' 1 '1998-12-01' NULL 2 'Bar Weekly Review' 1 '2005-01-01' NULL 3 'E-commerce App' 2 '2009-10-15' NULL 4 'CMS' 2 '2010-02-01' NULL ... and one subtable for each product type: item_magazine ============= item_magazine_id INT title VARCHAR product_id INT -> Foreign key to product.product_id issue_number INT pages INT copies INT close_date DATETIME release_date DATETIME E.g. 1 'Foo Magazine Regular Issue' 1 89 52 150000 '2010-06-25' '2010-06-31' 2 'Foo Magazine Summer Special' 1 90 60 175000 '2010-07-25' '2010-07-31' 3 'Bar Weekly Review Regular Issue' 2 12 16 20000 '2010-06-01' '2010-06-02' item_web_site ============= item_web_site_id INT name VARCHAR product_id INT -> Foreign key to product.product_id bandwidth INT hits INT date_from DATETIME date_to DATETIME E.g. 1 'The Carpet Store' 3 10 90000 '2010-06-01' NULL 2 'Penauts R Us' 3 20 180000 '2010-08-01' NULL 3 'Springfield Cattle Fair' 4 15 150000 '2010-05-01' '2010-10-31' Now I want to add some fees that relate to one specific item. Since there are very little subtypes, it's feasible to do this: fee === fee_id INT fee_description VARCHAR item_magazine_id INT -> Foreign key to item_magazine.item_magazine_id item_web_site_id INT -> Foreign key to item_web_site.item_web_site_id net_price DECIMAL E.g.: 1 'Front cover' 2 NULL 1999.99 2 'Half page' 2 NULL 500.00 3 'Square banner' NULL 3 790.50 4 'Animation' NULL 3 2000.00 I have tight foreign keys to handle cascaded editions and I presume I can add a constraint so only one of the IDs is NOT NULL. However, my intuition suggests that it would be cleaner to get rid of the item_WHATEVER_id columns and keep a separate table: fee_to_item =========== fee_id INT -> Foreign key to fee.fee_id product_id INT -> Foreign key to product.product_id item_id INT -> ??? But I can't figure out how to create foreign keys on item_id since the source table varies depending on product_id. Should I stick to my original idea?

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  • Is it ok to dynamic cast "this" as a return value?

    - by Panayiotis Karabassis
    This is more of a design question. I have a template class, and I want to add extra methods to it depending on the template type. To practice the DRY principle, I have come up with this pattern (definitions intentionally omitted): template <class T> class BaseVector: public boost::array<T, 3> { protected: BaseVector<T>(const T x, const T y, const T z); public: bool operator == (const Vector<T> &other) const; Vector<T> operator + (const Vector<T> &other) const; Vector<T> operator - (const Vector<T> &other) const; Vector<T> &operator += (const Vector<T> &other) { (*this)[0] += other[0]; (*this)[1] += other[1]; (*this)[2] += other[2]; return *dynamic_cast<Vector<T> * const>(this); } } template <class T> class Vector : public BaseVector<T> { public: Vector<T>(const T x, const T y, const T z) : BaseVector<T>(x, y, z) { } }; template <> class Vector<double> : public BaseVector<double> { public: Vector<double>(const double x, const double y, const double z); Vector<double>(const Vector<int> &other); double norm() const; }; I intend BaseVector to be nothing more than an implementation detail. This works, but I am concerned about operator+=. My question is: is the dynamic cast of the this pointer a code smell? Is there a better way to achieve what I am trying to do (avoid code duplication, and unnecessary casts in the user code)? Or am I safe since, the BaseVector constructor is private?

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  • Grid sorting with persistent master sort

    - by MikeWyatt
    I have a UI with a grid. Each record in the grid is sorted by a "master" sort column, let's call it a page number. Each record is a story in a magazine. I want the user to be able to drag and drop a record to a new position in the grid and automatically update the page number field to reflect the updated position. Easy enough, right? Now imagine that I also want to have the grid sortable by any other column (story title, section, author name, etc.). How does the drag and drop operation work now? Revert to page number sort during or after the drag and drop operation? This could confuse the user (why did my sort just change?). It would also result in arbitrary row positioning. Would the story now be before the row that was after it when the user dropped it? Or, would it be after the row that was before it? Those rows may now be widely separated after the master order sort. Disable the drag and drop feature if the grid isn't currently sorted by the page number? This would be easy, but the user might wonder why he can't drag and drop at certain times. Knowing to first sort by page number may not be very intuitive. Let the user rearrange his rows, but not make any changes to the page number? Require the user to enter a "Arrange Stories" mode, in which the grid sort is temporarily switched to page number and drag and drop is enabled? They would then exit the mode, and the previous sort would be reapplied. The big difference between this and the second option is that it would be more explicit than simply clicking on a column header. Any other ideas, or reasons why one of the above is the way to go? EDIT I'd like to point out that any of the above is technically possible, and easy to implement. My question is design-related. What is the most intuitive way to solve this problem, from the user's perspective?

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  • Designing a frontend/backend architecture

    - by wrp
    What are some good information sources on designing programs with a client/server architecture? This is for development of a desktop application, not a Web service. The only books I have found on client/server apps deal with the case of a thin client connecting to a remote database. Two good examples of what I mean are Mathematica and SuperCollider. I'm looking for platform- and language-agnostic discussion of the issues in developing a frontend/backend system. Especially useful topics would be allocation of responsibilities and options for message passing.

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  • Question about best practices and Macros from the book 'C++ Coding Standards'

    - by Victor T.
    From Herb Sutter and Andrei Alexandrescu's 'C++ Coding Standards', Item 16: Avoid Macros under Exceptions for this guideline they wrote: For conditional compilation (e.g., system-dependent parts), avoid littering your code with #ifdefs. Instead, prefer to organize code such that the use of macros drives alternative implementations of one common interface, and then use the interface throughout. I'm having trouble understanding exactly what they mean by this. How can you drive alternate implementations without the use of #ifdef conditional compile macro directives? Can someone provide an example to help illustrate what's being proposed by the above paragraph? Thanks

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  • How to handle customers with multiple addresses in CakePHP

    - by Ryan
    I'm putting together a system to track customer orders. Each order will have three addresses; a Main contact address, a billing address and a shipping address. I do not want to have columns in my orders table for the three addresses, I'd like to reference them from a separate table and have some way to enumerate the entry so I can determine if the addressing is main, shipping or billing. Does it make sense to create a column in the address table for AddressType and enumerate that or create another table - AddressTypes - that defines the address enumeration and link to that table? I have found other questions that touch on this topic and that is where I've taken my model. The problem I'm having is taking that into the cakePHP convention. I've been struggling to internalize the direction OneToMany relationships are formed - the way the documentation states feels backwards to me. Any help would be appreciated, Thanks!

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  • NullReferenceException makes me want to shoot myself

    - by rockinthesixstring
    Ok, so once upon a time, my code worked. Since then I did some refactoring (basic stuff so I thought) but now I'm getting a null reference exception, and I can't bloody well figure out why. Here's where it starts. note, this is the logout method, but all of my ActivityLogs sections are throwing this error Function LogOut(ByVal go As String) As ActionResult ActivityLogService.AddActivity(AuthenticationHelper.RetrieveAuthUser.ID, _ IActivityLogService.LogType.UserLogout, _ HttpContext.Request.UserHostAddress) ActivityLogService.SubmitChanges() ''# more stuff happens after this End Function The service is pretty straight forward (notice the ERROR THROWN HERE) Public Sub AddActivity(ByVal userid As Integer, ByVal activity As Integer, ByVal ip As String) Implements IActivityLogService.AddActivity Dim _activity As ActivityLog = New ActivityLog With {.Activity = activity, .UserID = userid, .UserIP = ip.IPAddressToNumber, .ActivityDate = DateTime.UtcNow} ActivityLogRepository.Create(_activity) ''#ERROR THROWN HERE End Sub And the Interface that the Service uses looks like this Public Interface IActivityLogService Sub AddActivity(ByVal userid As Integer, ByVal activity As Integer, ByVal ip As String) Function GetUsersLastActivity(ByVal UserID As Integer) As ActivityLog Sub SubmitChanges() ''' <summary> ''' The type of activity done by the user ''' </summary> ''' <remarks>Each int refers to an activity. ''' There can be no duplicates or modifications ''' after this application goes live</remarks> Enum LogType As Integer ''' <summary> ''' A new session started ''' </summary> SessionStarted = 1 ''' <summary> ''' A new user is Added/Created ''' </summary> UserAdded = 2 ''' <summary> ''' User has updated their profile ''' </summary> UserUpdated = 3 ''' <summary> ''' User has logged into they system ''' </summary> UserLogin = 4 ''' <summary> ''' User has logged out of the system ''' </summary> UserLogout = 5 ''' <summary> ''' A new event has been added ''' </summary> EventAdded = 6 ''' <summary> ''' An event has been updated ''' </summary> EventUpdated = 7 ''' <summary> ''' An event has been deleted ''' </summary> EventDeleted = 8 ''' <summary> ''' An event has received a Up/Down vote ''' </summary> EventVoted = 9 ''' <summary> ''' An event has been closed ''' </summary> EventCloseVoted = 10 ''' <summary> ''' A comment has been added to an event ''' </summary> CommentAdded = 11 ''' <summary> ''' A comment has been updated ''' </summary> CommentUpdated = 12 ''' <summary> ''' A comment has been deleted ''' </summary> CommentDeleted = 13 ''' <summary> ''' An event or comment has been reported as spam ''' </summary> SpamReported = 14 End Enum End Interface And the repository is equally straight forward Public Sub Create(ByVal activity As ActivityLog) Implements IActivityLogRepository.Create dc.ActivityLogs.InsertOnSubmit(activity) End Sub The stack trace is as follows [NullReferenceException: Object reference not set to an instance of an object.] MyApp.Core.Domain.ActivityLogService.AddActivity(Int32 userid, Int32 activity, String ip) in E:\Projects\MyApp\MyApp.Core\Domain\Services\ActivityLogService.vb:49 MyApp.Core.Controllers.UsersController.Authenticate(String go) in E:\Projects\MyApp\MyApp.Core\Controllers\UsersController.vb:258 lambda_method(Closure , ControllerBase , Object[] ) +163 System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +51 System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary2 parameters) +409 System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary2 parameters) +52 System.Web.Mvc.<c_DisplayClass15.b_12() +127 System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func1 continuation) +436 System.Web.Mvc.<>c__DisplayClass17.<InvokeActionMethodWithFilters>b__14() +61 System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList1 filters, ActionDescriptor actionDescriptor, IDictionary2 parameters) +305 System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +830 System.Web.Mvc.Controller.ExecuteCore() +136 System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +232 System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +39 System.Web.Mvc.<>c__DisplayClassb.<BeginProcessRequest>b__5() +68 System.Web.Mvc.Async.<>c__DisplayClass1.<MakeVoidDelegate>b__0() +44 System.Web.Mvc.Async.<>c__DisplayClass81.b__7(IAsyncResult ) +42 System.Web.Mvc.Async.WrappedAsyncResult`1.End() +141 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +54 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40 System.Web.Mvc.<c_DisplayClasse.b_d() +61 System.Web.Mvc.SecurityUtil.b_0(Action f) +31 System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Action action) +56 System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +110 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +38 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +690 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +194 here's an image of the error when attached to the debugger. And here's an image of the DB schema in question Can anyone shed some light on what I might be missing here?

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  • Converting ASP.NET MVC to n-Tiered Architecture

    - by Jeff
    I just built an application using ASP.NET MVC. The programmers at my company want to build all future modules using n-Tiered (Presentation Layer, Business Logic Layer, Data Access Layer) architecture. I am not the programmer and need to know why this makes sense? Do I have to completely rewrite the entire code or can it be converted? We are building an HRIS system with Business Intelligence. Somebody please explain why or why not this approach does or does not make sense.

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  • Can I change class types in a setter with an object-oriented language?

    - by user214626
    Hello, Here is the problem statement : Calling a setter on the object should result in the object to change to an object of a different class, which language can support this ? Ex. I have a class called "Man" (Parent Class), and two children namely "Toddler" and "Old Man", they are its children because they override a behaviour in Man called as walk.( i.e Toddler sometimes walks using both his hands and legs kneeled down and the Old man uses a stick to support himself). The Man class has a attribute called age, I have a setter on Man,say it is called setAge(int ageValue). I have 3 objects, 2 toddlers, 1 old-Man. (The system is up and running,i guess when we say objects it is obvious) .I will make this call, toddler.setAge(80), I expect the toddler to change to an object of type Old Man. Is this possible.Please suggest. Thanks,

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  • how to tackle a custom forms database

    - by Neil Hickman
    I'm currently researching a project for the place that I work in. We are trying to create a system that will allow forms to be set up dynamically from a database. My question is what database structure would best suit something like this? I currently have a structure of: forms_form forms_formfields forms_formdata I don't think this is the most appropriate layout for this. Basically to make is make sense I need to be able to make a form within the database that can have infinite fields all customized and have the data when submitted stored in the database.

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  • What information do you capture when your software crashes in the field?

    - by Russ
    I am working on rewriting my unexpected error handling process, and I would like to ask the community: What information do you capture both automatic, and manually, when software you have written crashes? Right now, I capture a few items, some of which are: Automatic: Name of app that crashed Version of app that crashed Stack trace Operating System version RAM used by the application Number of processors Screen shot: (Only on non-public applications) User name and contact information (from Active Directory) Manual: What context is the user in (i.e.: what company, tech support call number, RA number, etc...) When did the user expect to happen? (Typical response: "Not to crash”) Steps to reproduce. What other bits of information do you capture that helps you discover the true cause of an applications problem, especially given that most users simply mash the keyboard when asked to tell you what happened. For the record I’m using C#, WPF and .NET version 4, but I don’t necessarily want to limit myself to those. Related: http://stackoverflow.com/questions/1226671/what-to-collect-information-when-software-crashes Related: http://stackoverflow.com/questions/701596/what-should-be-included-in-the-state-of-the-art-error-and-exception-handling-stra

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  • What would be the best schema to store the 'address' for different entities?

    - by Cesar
    Suppose we're making a system where we have to store the addrees for buildings, persons, cars, etc. The address 'format' should be something like: State (From a State list) County (From a County List) Street (free text, like '5th Avenue') Number (free text, like 'Chrysler Building, Floor 10, Office No. 10') (Yes I don't live in U.S.A) What would be the best way to store that info: Should I have a Person_Address, Car_Address, ... Or the address info should be in columns on each entity, Could we have just one address table and try to link each row to a different entity? Or are there another 'better' way to handle this type of scenario? How would yo do it?

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  • How to represent a Many-To-Many relationship in XML or other simple file format?

    - by CSharperWithJava
    I have a list management appliaction that stores its data in a many-to-many relationship database. I.E. A note can be in any number of lists, and a list can have any number of notes. I also can export this data to and XML file and import it in another instance of my app for sharing lists between users. However, this is based on a legacy system where the list to note relationship was one-to-many (ideal for XML). Now a note that is in multiple lists is esentially split into two identical rows in the DB and all relation between them is lost. Question: How can I represent this many-to-many relationship in a simple, standard file format? (Preferably XML to maintain backwards compatibility)

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  • Buffering db inserts in multithreaded program

    - by Winter
    I have a system which breaks a large taks into small tasks using about 30 threads as a time. As each individual thread finishes it persists its calculated results to the database. What I want to achieve is to have each thread pass its results to a new persisance class that will perform a type of double buffering and data persistance while running in its own thread. For example, after 100 threads have moved their data to the buffer the persistance class then the persistance class swaps the buffers and persists all 100 entries to the database. This would allow utilization of prepared statements and thus cut way down on the I/O between the program and the database. Is there a pattern or good example of this type of multithreading double buffering?

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  • General question: Filesystem or database?

    - by poeschlorn
    Hey guys, i want to create a small document management system. there are several users who store their files. each file which is uploaded contains an info which user uploaded it and the document content itself. In a view there are displayed all files of ONE specific user, ordered by date. What would be better: 1) giving the documents a name or metadata(XML) which contain the date and user (and iterate through them to get the metadata) or 2) giving the files a random/unique name and store metadata in a DB? something like this: date | user | filename What would you say and why? The used programming language is java and the DB is MySQL.

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  • Are there any modern GUI toolkits which implement a heirarchical menu buffer zone?

    - by scomar
    In Bruce Tognazzini's quiz on Fitt's Law, the question discussing the bottleneck in the hierarchical menu (as used in almost every modern desktop UI), talks about his design for the original Mac: The bottleneck is the passage between the first-level menu and the second-level menu. Users first slide the mouse pointer down to the category menu item. Then, they must carefully slide the mouse directly across (horizontally) in order to move the pointer into the secondary menu. The engineer who originally designed hierarchicals apparently had his forearm mounted on a track so that he could move it perfectly in a horizontal direction without any vertical component. Most of us, however, have our forarms mounted on a pivot we like to call our elbow. That means that moving our hand describes an arc, rather than a straight line. Demanding that pivoted people move a mouse pointer along in a straight line horizontally is just wrong. We are naturally going to slip downward even as we try to slide sideways. When we are not allowed to slip downward, the menu we're after is going to slam shut just before we get there. The Windows folks tried to overcome the pivot problem with a hack: If they see the user move down into range of the next item on the primary menu, they don't instantly close the second-level menu. Instead, they leave it open for around a half second, so, if users are really quick, they can be inaccurate but still get into the second-level menu before it slams shut. Unfortunately, people's reactions to heightened chance of error is to slow down, rather than speed up, a well-established phenomenon. Therefore, few users will ever figure out that moving faster could solve their problem. Microsoft's solution is exactly wrong. When I specified the Mac hierarchical menu algorthm in the mid-'80s, I called for a buffer zone shaped like a <, so that users could make an increasingly-greater error as they neared the hierarchical without fear of jumping to an unwanted menu. As long as the user's pointer was moving a few pixels over for every one down, on average, the menu stayed open, no matter how slow they moved. (Cancelling was still really easy; just deliberately move up or down.) This just blew me away! Such a simple idea which would result in a huge improvement in usability. I'm sure I'm not the only one who regularly has the next level of a menu slam shut because I don't move the mouse pointer in a perfectly horizontal line. So my question is: Are there any modern UI toolkits which implement this brilliant idea of a < shaped buffer zone in hierarchical menus? And if not, why not?!

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  • Best Practice for CouchDB Document Versioning

    - by Groundwater
    Following my question here I am exmploring ideas for a generic approach to document versioning in CouchDB. While I imagine there may be no canonical approach, I had the following idea and am looking for feedback. I would like to maintain readable document ids as much as possible, so a document existing at /document1 would contain a pointer document to all existing versions on the system. The actual revision documents would be at something like /document1/308ef032a3801a where 308ef032a3801a is some random number or hash. Example The pointer document { "_id" : "document1", "versions" : [ "document1/308ef032a3801a" ] } The version document { "_id" : "document1/308ef032a3801a", ... actual content }

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  • What is the best way to expose a callback API - C++

    - by rursw1
    Hi, I have a C++ library that should expose some system\ resource calls as callbacks from the linked application. For example: the interfacing application (which uses this library) can send socket management callback functions - send, receive, open, close etc., and the library will use this implementation in stead of the library's implementation. (This way enables the application to manage the sockets by itself, can be useful). This library has to expose also more callbacks, like, for example, a password validation, so I wonder if there is a preferred method to expose the callback sending option in one API. Something like: int AddCallbackFunc (int functionCallbackType, <generic function prototype>, <generic way to pass some additional arguments>) Then within my library I will assign the callback to the appropriate function pointer according to the functionCallbackType parameter. Is there any way to implement it in a generic way which will fit ANY function prototype and ANY additional arguments? Your help will be more than appreciated... Thanks!

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  • How to Execute Base Class's ExtractPageData() Before Implementors's ExtractPageData()?

    - by DaveDev
    I have the following page public partial class GenericOfflineCommentary : OfflineFactsheetBase { } where OfflineFactsheetBase is defined as public class OfflineFactsheetBase : System.Web.UI.Page { public OfflineFactsheetBase() { this.Load += new EventHandler(this.Page_Load); this.PreInit += new EventHandler(this.Page_PreInit); } protected void Page_PreInit(object sender, EventArgs e) { if (Request.QueryString["data"] != null) { this.PageData = StringCompressor.DecompressString(Request.QueryString["data"]); this.ExtractPageData(); } } } OfflineFactsheetBase has the following virtual method: public virtual void ExtractPageData() { // get stuff relevant to all pages that impmement OfflineFactsheetBase } which is implemented in all pages that impmement OfflineFactsheetBase as follows: public partial class GenericOfflineCommentary : OfflineFactsheetBase { public override void ExtractPageData() { // get stuff relevant to an OfflineCommentary page. } } Currently, only GenericOfflineCommentary's ExtractPageData() is firing. How can I modify this to first run OfflineFactsheetBase's ExtractPageData() and then GenericOfflineCommentary's?

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  • How to Execute Base Class's Method Before Implementors's Method?

    - by DaveDev
    I have the following page public partial class GenericOfflineCommentary : OfflineFactsheetBase { } where OfflineFactsheetBase is defined as public class OfflineFactsheetBase : System.Web.UI.Page { public OfflineFactsheetBase() { this.Load += new EventHandler(this.Page_Load); this.PreInit += new EventHandler(this.Page_PreInit); } protected void Page_PreInit(object sender, EventArgs e) { if (Request.QueryString["data"] != null) { this.PageData = StringCompressor.DecompressString(Request.QueryString["data"]); this.ExtractPageData(); } } } OfflineFactsheetBase has the following virtual method: public virtual void ExtractPageData() { // get stuff relevant to all pages that impmement OfflineFactsheetBase } which is implemented in all pages that impmement OfflineFactsheetBase as follows: public partial class GenericOfflineCommentary : OfflineFactsheetBase { public override void ExtractPageData() { // get stuff relevant to an OfflineCommentary page. } } Currently, only GenericOfflineCommentary's ExtractPageData() is firing. How can I modify this to first run OfflineFactsheetBase's ExtractPageData() and then GenericOfflineCommentary's? edit: I'm trying to avoid having to call base.ExtractPageData() in every implementor. Is this possible?

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  • When does logic belong in the Business Object/Entity, and when does it belong in a Service?

    - by Casey
    In trying to understand Domain Driven Design I keep returning to a question that I can't seem to definitively answer. How do you determine what logic belongs to a Domain entity, and what logic belongs to a Domain Service? Example: We have an Order class for an online store. This class is an entity and an aggregate root (it contains OrderItems). Public Class Order:IOrder { Private List<IOrderItem> OrderItems Public Order(List<IOrderItem>) { OrderItems = List<IOrderItem> } Public Decimal CalculateTotalItemWeight() //This logic seems to belong in the entity. { Decimal TotalWeight = 0 foreach(IOrderItem OrderItem in OrderItems) { TotalWeight += OrderItem.Weight } return TotalWeight } } I think most people would agree that CalculateTotalItemWeight belongs on the entity. However, at some point we have to ship this order to the customer. To accomplish this we need to do two things: 1) Determine the postage rate necessary to ship this order. 2) Print a shipping label after determining the postage rate. Both of these actions will require dependencies that are outside the Order entity, such as an external webservice to retrieve postage rates. How should we accomplish these two things? I see a few options: 1) Code the logic directly in the domain entity, like CalculateTotalItemWeight. We then call: Order.GetPostageRate Order.PrintLabel 2) Put the logic in a service that accepts IOrder. We then call: PostageService.GetPostageRate(Order) PrintService.PrintLabel(Order) 3) Create a class for each action that operates on an Order, and pass an instance of that class to the Order through Constructor Injection (this is a variation of option 1 but allows reuse of the RateRetriever and LabelPrinter classes): Public Class Order:IOrder { Private List<IOrderItem> OrderItems Private RateRetriever _Retriever Private LabelPrinter _Printer Public Order(List<IOrderItem>, RateRetriever Retriever, LabelPrinter Printer) { OrderItems = List<IOrderItem> _Retriever = Retriever _Printer = Printer } Public Decimal GetPostageRate { _Retriever.GetPostageRate(this) } Public void PrintLabel { _Printer.PrintLabel(this) } } Which one of these methods do you choose for this logic, if any? What is the reasoning behind your choice? Most importantly, is there a set of guidelines that led you to your choice?

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