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• How best to use XPath with very large XML files in .NET?

  - by glenatron

  I need to do some processing on fairly large XML files ( large here being potentially upwards of a gigabyte ) in C# including performing some complex xpath queries. The problem I have is that the standard way I would normally do this through the System.XML libraries likes to load the whole file into memory before it does anything with it, which can cause memory problems with files of this size. I don't need to be updating the files at all just reading them and querying the data contained in them. Some of the XPath queries are quite involved and go across several levels of parent-child type relationship - I'm not sure whether this will affect the ability to use a stream reader rather than loading the data into memory as a block. One way I can see of making it work is to perform the simple analysis using a stream-based approach and perhaps wrapping the XPath statements into XSLT transformations that I could run across the files afterward, although it seems a little convoluted. Alternately I know that there are some elements that the XPath queries will not run across, so I guess I could break the document up into a series of smaller fragments based on it's original tree structure, which could perhaps be small enough to process in memory without causing too much havoc. I've tried to explain my objective here so if I'm barking up totally the wrong tree in terms of general approach I'm sure you folks can set me right...

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• MVC design question for forms

  - by kenny99

  Hi, I'm developing an app which has a large amount of related form data to be handled. I'm using a MVC structure and all of the related data is represented in my models, along with the handling of data validation from form submissions. I'm looking for some advice on a good way to approach laying out my controllers - basically I will have a huge form which will be broken down into manageable categories (similar to a credit card app) where the user progresses through each stage/category filling out the answers. All of these form categories are related to the main relation/object, but not to each other. Does it make more sense to have each subform/category as a method in the main controller class (which will make that one controller fairly massive), or would it be better to break each category into a subclass of the main controller? It may be just for neatness that the second approach is better, but I'm struggling to see much of a difference between either creating a new method for each category (which communicates with the model and outputs errors/success) or creating a new controller to handle the same functionality. Thanks in advance for any guidance!

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• Setting style on first and last visible TabItem of TabControl

  - by Donnelle

  I want to set a style on the first and last TabItems in a TabControl, and have them updated as the visibility of the TabItems is changed. I can't see a way to do so with triggers. What we're after looks like this: | | And the visibility of TabItems are determined by binding. I do have it working in code. On TabItem visibility changed, enumerate through TabItems until you find the first visible one. Set the style on that one. For all other visible TabItems, set them to the pointy style (so that the previously first visible one is now pointy). Then start from the end until you find a visible TabItem and set the last style on that one. (This also lets us address an issue with TabControl where it will display the content of a non-visible TabItem if none of the visible TabItems are selected.) There's undoubtably improvements I could make to my method, but I'm not convinced that it IS the right approach. How would you approach this?

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• Locking behaviour is different via network shares

  - by MattH

  I have been trying to lock a file so that other cloned services cannot access the file. I then read the file, and then move the file when finished. The Move is allowed by using FileShare.Delete. However in later testing, we found that this approach does not work if we are looking at a network share. I appreciate my approach may not have been the best, but my specific question is: Why does the below demo work against the local file, but not against the network file? The more specific you can be the better, as I've found very little information in my searches that indicates network shares behave differently to local disks. string sourceFile = @"C:\TestFile.txt"; string localPath = @"C:\MyLocalFolder\TestFile.txt"; string networkPath = @"\\MyMachine\MyNetworkFolder\TestFile.txt"; File.WriteAllText(sourceFile, "Test data"); if (!File.Exists(localPath)) File.Copy(sourceFile, localPath); foreach (string path in new string[] { localPath, networkPath }) { using (FileStream fsLock = File.Open(path, FileMode.Open, FileAccess.ReadWrite, (FileShare.Read | FileShare.Delete))) { string target = path + ".out"; File.Move(path, target); //This is the point of failure, when working with networkPath if (File.Exists(target)) File.Delete(target); } if (!File.Exists(path)) File.Copy(sourceFile, path); }

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• Which language should I pick up: VB.Net or C#

  - by magius

  I'm looking to pick up either C# or VB.Net. I'd done a fair bit of VB6 programming in the past. I'm looking at getting the book, Visual Basic .NET or C#, Which to Choose? but I'm hoping that someone has read it, or used both languages and can offer advice. Should I just RTFB? Edit: Anders Sandvig raised a valid question. I'm intending to develop ActiveX applications that will be served through IE. Edit: Given that the functionality is pretty close and my favored approach to learning is to "just build it" and solve problems by looking it up on the internet, I've decided that the choice of language will be based on how easy it is to learn it. I looked around and found sites like C# Corner that supports my approach. Personal note: I wish I could also select Seb Nilsson's response as an accepted answer as well. Thanks guys for your input! Alright, then! I admit, theoretically, this topic is subjective; but a quick tally of answers seems to skew votes heavily in C#'s favor. Anyway, I'm really after experiences like what Keith's alluding to. I'm hoping he'll return to this topic and drop us a few more gems.

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• Design pattern to use instead of multiple inheritance

  - by mizipzor

  Coming from a C++ background, Im used to multiple inheritance. I like the feeling of a shotgun squarely aimed at my foot. Nowadays, I work more in C# and Java, where you can only inherit one baseclass but implement any number of interfaces (did I get the terminology right?). For example, lets consider two classes that implement a common interface but different (yet required) baseclasses: public class TypeA : CustomButtonUserControl, IMagician { public void DoMagic() { // ... } } public class TypeB : CustomTextUserControl, IMagician { public void DoMagic() { // ... } } Both classes are UserControls so I cant substitute the base class. Both needs to implement the DoMagic function. My problem now is that both implementations of the function are identical. And I hate copy-and-paste code. The (possible) solutions: I naturally want TypeA and TypeB to share a common baseclass, where I can write that identical function definition just once. However, due to having the limit of just one baseclass, I cant find a place along the hierarchy where it fits. One could also try to implement a sort of composite pattern. Putting the DoMagic function in a separate helper class, but the function here needs (and modifies) quite a lot of internal variables/fields. Sending them all as (reference) parameters would just look bad. My gut tells me that the adapter pattern could have a place here, some class to convert between the two when necessery. But it also feels hacky. I tagged this with language-agnostic since it applies to all languages that use this one-baseclass-many-interfaces approach. Also, please point out if I seem to have misunderstood any of the patterns I named. In C++ I would just make a class with the private fields, that function implementation and put it in the inheritance list. Whats the proper approach in C#/Java and the like?

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• SharePoint 2010 / ASP.Net Integration - Looking for advice

  - by jpennal

  I have been Googling a problem that I have with trying to integrate the web application that I am working on with SharePoint 2010. The web application is a wiki style tool that allows users to log in via forms authentication or WIA against Active Directory and create content for themselves and others. What we would like to do is to allow a user have a page with the content they have created in our web application mixed in with content that they have living on the SharePoint server. For example, they may want to see a list of documents that they have on the SharePoint server mixed in with some of their content. To accomplish this, we would like to take the credentials the user has logged into our web application with (for example MYDOMAIN\jsmith) and be able to query SharePoint for the documents of that same user (MYDOMAIN\jsmith) WITHOUT the user being prompted to re-enter their credentials to access the SharePoint server (we are trying to avoid the double-hop problem) We have come up with some options for how we want to do this, but we are unsure of what the best approach is. For example, we could - Have a global user, shared by all users to get information we need from SharePoint. The downside is that we cannot filter SharePoint content to a particular user - We could store the users credentials when they log in, but that would only work for users authenticating via forms auth and would be a security issue that some users/clients would not like - Writing a SharePoint extension using WCF to allow us to access the information we need, however we'd still have the issue of figuring out how to impersonate the user we want. Neither of these options are ideal and in our investigation we came across the Claims Authentication/STS option which seems like it is trying to solve the problem we are having. So my question is, based on what I have written, is Claims/STS the best approach for us? We have not been able to find much direction on how to use this method to call into SharePoint from a Web Application and pass along the existing credentials. Does anyone have any experience with any of these issues?

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• Serializing MDI Winforms for persistency

  - by Serge

  Hello, basically my project is an MDI Winform application where a user can customize the interface by adding various controls and changing the layout. I would like to be able to save the state of the application for each user. I have done quite a bit of searching and found these: http://stackoverflow.com/questions/2076259/how-to-auto-save-and-auto-load-all-properties-in-winforms-c http://stackoverflow.com/questions/1669522/c-save-winform-or-controls-to-file Basically from what I understand, the best approach is to serialize the data to XML, however winform controls are not serializable, so I would have use surrogate classes: http://www.codeproject.com/KB/dotnet/Surrogate_Serialization.aspx Now, do I need to write a surrogate class for each of my controls? I would need to write some sort of a recursive algorithm to save all my controls, what is the best approach to do accomplish that? How would I then restore all the windows, should I use the memento design pattern for that? If I want to implement multiple users later, should I use Nhibernate to store all the object data in a database? I am still trying to wrap my head around the problem and if anyone has any experience or advice I would greatly appreciate it, thanks.

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• Multi-tenant Access Control: Repository or Service layer?

  - by FreshCode

  In a multi-tenant ASP.NET MVC application based on Rob Conery's MVC Storefront, should I be filtering the tenant's data in the repository or the service layer? 1. Filter tenant's data in the repository: public interface IJobRepository { IQueryable<Job> GetJobs(short tenantId); } 2. Let the service filter the repository data by tenant: public interface IJobService { IList<Job> GetJobs(short tenantId); } My gut-feeling says to do it in the service layer (option 2), but it could be argued that each tenant should in essence have their own "virtual repository," (option 1) where this responsibility lies with the repository. Which is the most elegant approach: option 1, option 2 or is there a better way? Update: I tried the proposed idea of filtering at the repository, but the problem is that my application provides the tenant context (via sub-domain) and only interacts with the service layer. Passing the context all the way to the repository layer is a mission. So instead I have opted to filter my data at the service layer. I feel that the repository should represent all data physically available in the repository with appropriate filters for retrieving tenant-specific data, to be used by the service layer. Final Update: I ended up abandoning this approach due to the unnecessary complexities. See my answer below.

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• Flexible design - customizable entity model, UI and workflow

  - by Ngm

  Hi All, I want to achieve the following aspects in the software I am building: 1. Customizable entity model 2. Customizable UI 3. Customizable workflow I have thought about an approach to achieve this, I want you to review this and make suggestions: Entity objects should be plain objects and will hold just data Separate Entity model and DB Schema by using an framework (like NHibernate?). This will allow easy modification of entity objects. Business logic to fetch/modify entities has to be granular enough so that they can be invoked as part of the workflow. Business objects should not hold any state, and hence will contain only static methods The workflow will decide depending upon the "state" of an entity/entities which methods on business object/objects to invoke. The workflow should obtain the results of the processing and then pass on the business objects to the appropriate UI screen. The UI screen has to contain instructions about how to display a given entity/entites. Possibly the UI has to be generated dynamically based on a set of UI instructions. (like XUL) What do you think about this approach? Suggest which existing frameworks (like NHiberante, Window Workflow) fit into this model, so that I will not spend time on coding these frameworks Also suggest is there any asp.net framework that can generate dynamic asp.net ajax pages based on a set of UI instructions (like Mozilla XUL)? I have recently been exploring Apache Ofbiz and was impressed by its ability to customize most areas of the application: UI, workflow, entities. Is there any similar (not necessarily an ERP system) application developed in C#/.Net which offers a similar level of customization? I am looking for examples of applications developed in C# that are highly customizable in terms of UI, Workflow and Entity Model

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• What are the drawbacks of using PHP to create variables in my CSS stylesheet?

  - by Greg

  One significant drawback of CSS is that one can't use variables. For example, I'd like to use variables to control the location of imported CSS, and it would be awesome to create variables for colors that are used repeatedly in a design. One approach is to use a PHP file for the CSS stylesheet. In other words, create a "style.php" with... <?php header("Content-type: text/css"); ?> ...at the top of the file, and then link to it using... <link href="style.php" rel="stylesheet" type="text/css" /> ...in any file that uses these styles. So what's the catch? I think it might be performance -- I did a few quick experiments in Firefox/Firebug and as one would expect, the CSS stylesheet is cached, but the PHP stylesheet isn't. So we're paying the price of an additional GET. The other annoying thing is that TextMate does not syntax highlight properly for CSS in a .php file. Are there other drawbacks? Have you used this approach, and if so, would you recommend it?

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• Splitting MS Access Database - Front End Part Location

  - by kristof

  One of the best practices as specified by Microsoft for Access Development is splitting Access application into 2 parts; Front End that hold all the object except tables and the Back End that holds the tables. The msdn page links there to the article Splitting Microsoft Access Databases to Improve Performance and Simplify Maintainability that describes the process in details. It is recommended that in multi user environment the Back End is stored on the server/shared folder while the Front End is distributed to each user. That implies that each time there are any changes made to the front end they need to be deployed to every user machine. My question is: Assuming that the users themselves do not have rights to modify the Front End part of the application what would be the drawbacks/dangers of leaving this on the server as well next to the Back End copy? I can see the performance issues here, but are there any dangers here like possible corruptions etc? Thank you EDIT Just to clarify, the scenario specified in question assumes one Front End stored on the server and shared by users. I understand that the recommendation is to have FE deployed to each user machine, but my question is more about what are the dangers if that is not done. E.g. when you are given an existing solution that uses the approach of both FE and BE on the server. Assuming the the performance is acceptable and the customer is reluctant to change the approach would you still push the change? And why exactly? For example the danger of possible data corruption would definitely be the strong enough argument, but is that the case? It is a part of follow up of my previous question From SQL Server to MS Access 2007

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• Autologin for web application

  - by Maulin

  We want to AutoLogin feature to allow user directly login using link into our Web Application. What is the best way achieve this? We have following approches in our mind. 1) Store user credentials(username/password) in cookie. Send cookie for authentication. e.g. http: //www.mysite.com/AutoLogin (here username/password will be passed in cookie) OR Pass user credentials in link URL. http: //www.mysite.com/AutoLogin?userid=<&password=< 2) Generate randon token and store user random token and user IP on server side database. When user login using link, validate token and user IP on server. e.g. http: //www.mysite.com/AutoLogin?token=< The problem with 1st approach is if hacker copies link/cookie from user machine to another machine he can login. The problem with 2nd approach is the user ip will be same for all users of same organization behind proxy. Which one is better from above from security perspective? If there is better solution which is other than mentioned above, please let us know.

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• Design suggestion for expression tree evaluation with time-series data

  - by Lirik

  I have a (C#) genetic program that uses financial time-series data and it's currently working but I want to re-design the architecture to be more robust. My main goals are: sequentially present the time-series data to the expression trees. allow expression trees to access previous data rows when needed. to optimize performance of the data access while evaluating the expression trees. keep a common interface so various types of data can be used. Here are the possible approaches I've thought about: I can evaluate the expression tree by passing in a data row into the root node and let each child node use the same data row. I can evaluate the expression tree by passing in the data row index and letting each node get the data row from a shared DataSet (currently I'm passing the row index and going to multiple synchronized arrays to get the data). Hybrid: an immutable data set is accessible by all of the expression trees and each expression tree is evaluated by passing in a data row. The benefit of the first approach is that the data row is being passed into the expression tree and there is no further query done on the data set (which should increase performance in a multithreaded environment). The drawback is that the expression tree does not have access to the rest of the data (in case some of the functions need to do calculations using previous data rows). The benefit of the second approach is that the expression trees can access any data up to the latest data row, but unless I specify what that row is, I'll have to iterate through the rows and figure out which one is the last one. The benefit of the hybrid is that it should generally perform better and still provide access to the earlier data. It supports two basic "views" of data: the latest row and the previous rows. Do you guys know of any design patterns or do you have any tips that can help me build this type of system? Should I use a DataSet to hold and present the data, or are there more efficient ways to present rows of data while maintaining a simple interface? FYI: All of my code is written in C#.

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• asp.net multiligual website culture settings

  - by Hemant Kothiyal

  Hi, In asp.net multilingual website in english Uk and swedish, i have three rsources file 1. en-GB.resx 2. sv-SE.resx 3. Culture neutral file. I have create one base class and all pages is inherited from that class. There i write following lines to set UICULTURE and culture 1. Thread.CurrentThread.CurrentUICulture = CultureInfo.CurrentUICulture.Name; 2. Thread.CurrentThread.CurrentCulture = CultureInfo.CurrentCulture.Name; Question: Suppose my browser language is Swedish(sv-SE) then this code will run because it find CurrentUICulture and CurrentCulture values as sv-SE. Now if suppose browser language is Swedish(sv) only, in that case values will be set as CurrentUICulture = sv; and CurrentCulture = sv-SE Now the problem is that user can able to view all text in Culture neutral resource file that i kept as english while all decimal saperators, currency and other will be appear in swedish. It looks confusing to usr. What would be right approach. I am thinking following solution. Please correct me? 1. i can create extra resource file for sv also. 2. I check value of CurrentUICulture in base class and if it is sv then replace it with sv-SE Please correct me which one is right approach or Is there any other good way of doing?

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• Crashing when pushing a XIB based view controller onto navigation controller stack

  - by Michael

  I was attempting to clean up the implementation for a sub-panel on a navigation controller stack, so that the navigation bar could be customized in the XIB instead of doing it manually in the viewDidLoad method. The original (working) setup had the XIB set up with the "File's Owner" class set to the view controller class, and then the view at the top level. This works fine. In the "Interface Builder User Guide", p. 71, it describes the recommended way to build the XIBs for sub-panels ("additional navigation levels"). This approach leaves the "File's Owner" class as NSObject, but adds a UIViewController at the top level, and nests the view (and navigation item) underneath it. The UIViewController's view automatically gets connected to the contained view. When I try to push the controller init'd with this new XIB, the app crashes because of a missing view: SettingsViewController *controller = [[SettingsViewController alloc] initWithNibName:@"SettingsView" bundle:nil]; [self.navigationController pushViewController:controller animated:YES]; 2010-04-23 11:17:37.135 xxxx[1173:207] * Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '-[UIViewController _loadViewFromNibNamed:bundle:] loaded the "SettingsTestView" nib but the view outlet was not set.' I've double checked everything, and tried building a clean XIB from scratch, but get the same result. I looked through a number of the code sample projects, and NONE of them use the documented/recommended approach--they all use the File's Owner class and manually set up the navigation bar in viewDidLoad like I originally had it. Is it possible to get it working the "recommended" way? Thanks! Michael

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• Standardizing a Release/Tools group on a specific language

  - by grahzny

  I'm part of a six-member build and release team for an embedded software company. We also support a lot of developer tools, such as Atlassian's Fisheye, Jira, etc., Perforce, Bugzilla, AnthillPro, and a couple of homebrew tools (like my Django release notes generator). Most of the time, our team just writes little plugins for larger apps (ex: customize workflows in Anthill), long-term utility scripts (package up a release for QA), or things like Perforce triggers (don't let people check into a specific branch unless their change description includes a bug number; authenticate against Active Directory instead of Perforce's internal passwords). That's about the scale of our problems, although we sometimes tackle something slightly more sizable. My boss, who is reasonably technical, has asked us to standardize on one or two languages so we can more easily substitute for each other. He's advocating bash scripts and Perl, due to their universality and simplicity. I can see his point--we mostly do "glue", so why not use "glue" languages rather than saddle ourselves with something designed for much larger projects? Since some of the tools we work with are Java-based, we do need to use something that speaks JVM sometimes. (The path of least resistance for these projects is BeanShell and Groovy.) I feel a tremendous itch toward language advocacy, but I'm trying to avoid saying "We should use Python 'cause I like it and Perl is gross." Instead, I'm trying to come up with a good approach to defining our problem set: what problems do we solve with scripts? Would we benefit from a library of common functions by our team, or are most of our projects more isolated? What is it reasonable to expect my co-workers to learn? What languages give us the most ease of development and ease of modification? Can you folks suggest some useful ways to approach this problem, both for my own thinking process and to help me facilitate some brainstorming among my coworkers?

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• algorithm || method to write prog

  - by fatai

  I am one of the computer science student. My wonder is everyone solve problem with different or same method, but actually I dont know whether they use method or I dont know whether there are such common method to approach problem. All teacher give us problem which in simple form sometimes, but they dont introduce any approach or method(s) so that we can first choose method then apply that one to problem , afterward find solution then write code. I have found one method when I failed the course, More accurately, When I counter problem in language , I will get more paper and then ; first, input/ output step ; my prog will take this / these there argument(s) and return namely X , ex : in c, input length is not known and at same type , so I must use pointer desired output is in form of package , so use structure second, execution part ; in that step , I am writing all step which are goes to final output ex : in python ; 1.) [ + , [- , 4 , [ * , 1 , 2 ]], 5] 2.) [ + , [- , 4 , 2 ],5 ] 3.) [ + , 2 , 5] 4.) 7 ==> return 7 third, I will write test code ex : in c++ input : append 3 4 5 6 vector_x remove 0 1 desired output vector_x holds : 5 6 But now, I wonder other method ; used to construct class :::: for c++ , python, java used to communicate classes / computers used for solving embedded system problem ::::: for c Why I wonder , because I learn if you dont costruct algorithm on paper, you may achieve your goal. Like no money no lunch , I can say no algorithm no prog therefore , feel free when you write your own method , a way which is introduced by someone else but you are using and you find it is so efficient

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• What's the most concise cross-browser way to access an <iframe> element's window and document?

  - by Bungle

  I'm trying to figure out the best way to access an <iframe> element's window and document properties from a parent page. The <iframe> may be created via JavaScript or accessed via a reference stored in an object property or a variable, so, if I understand correctly, that rules out the use of document.frames. I've seen this done a number of ways, but I'm unsure about the best approach. Given an <iframe> created in this way: var iframe = document.createElement('iframe'); document.getElementsByTagName('body')[0].appendChild(iframe); I'm currently using this to access the document, and it seems to work OK across the major browsers: var doc = iframe.contentWindow || iframe.contentDocument; if (doc.document) { doc = doc.document; } I've also see this approach: var iframe = document.getElementById('my_iframe'); iframe = (iframe.contentWindow) ? iframe.contentWindow : (iframe.contentDocument.document) ? iframe.contentDocument.document : iframe.contentDocument; iframe.document.open(); iframe.document.write('Hello World!'); iframe.document.close(); That confuses me, since it seems that if iframe.contentDocument.document is defined, you're going to end up trying to access iframe.contentDocument.document.document. There's also this: var frame_ref = document.getElementsByTagName('iframe')[0]; var iframe_doc = frame_ref.contentWindow ? frame_ref.contentWindow.document : frame_ref.contentDocument; In the end, I guess I'm confused as to which properties hold which properties, whether contentDocument is equivalent to document or whether there is such a property as contentDocument.document, etc. Can anyone point me to an accurate/timely reference on these properties, or give a quick briefing on how to efficiently access an <iframe>'s window and document properties in a cross-browser way (without the use of jQuery or other libraries)? Thanks for any help!

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• Localization: How to allow the user to define custom resources without compiling?

  - by gehho

  In our application, we have a collection of data items, each with a DisplayedName property. This property should be localized, i.e. it should be displayed in the language selected by the user. Therefore, another property, DisplayedNameResourceKey, specifies which resource should be returned by the DisplayedName property. In simplified code this means something like this: public string DisplayedName { get { return MyResources.ResourceManager.GetObject(this.DisplayedNameResourceKey); } } public string DisplayedNameResourceKey { get; set; } Now, the problem is: The user should be able to edit these items including the DisplayedName, or more precisely the DisplayedNameResourceKey. And not only this, but the user should also be able to somehow define new resources which he can then reference. That is, he can either choose from a predefined set of resources (some commonly used names), or define a custom resource which then needs to be localized by the user as well. However, the user cannot add custom resources to MyResources at runtime and without compiling. Therefore, another approach is needed. It does not have to be an extremely user-friendly way (e.g. UI is not required) because this will typically be done by our service engineers. I was thinking about using a txt or csv file containing pairs of resource keys and the corresponding translations. A separate file would exist for every language at a predefined location. But I am not really satisfied with that idea because it involves a lot of work to resolve the resources. Does anyone know a good approach for such a situation?

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• Cache consistency & spawning a thread

  - by Dave Keck

  Background I've been reading through various books and articles to learn about processor caches, cache consistency, and memory barriers in the context of concurrent execution. So far though, I have been unable to determine whether a common coding practice of mine is safe in the strictest sense. Assumptions The following pseudo-code is executed on a two-processor machine: int sharedVar = 0; myThread() { print(sharedVar); } main() { sharedVar = 1; spawnThread(myThread); sleep(-1); } main() executes on processor 1 (P1), while myThread() executes on P2. Initially, sharedVar exists in the caches of both P1 and P2 with the initial value of 0 (due to some "warm-up code" that isn't shown above.) Question Strictly speaking – preferably without assuming any particular CPU – is myThread() guaranteed to print 1? With my newfound knowledge of processor caches, it seems entirely possible that at the time of the print() statement, P2 may not have received the invalidation request for sharedVar caused by P1's assignment in main(). Therefore, it seems possible that myThread() could print 0. References These are the related articles and books I've been reading. (It wouldn't allow me to format these as links because I'm a new user - sorry.) Shared Memory Consistency Models: A Tutorial hpl.hp.com/techreports/Compaq-DEC/WRL-95-7.pdf Memory Barriers: a Hardware View for Software Hackers rdrop.com/users/paulmck/scalability/paper/whymb.2009.04.05a.pdf Linux Kernel Memory Barriers kernel.org/doc/Documentation/memory-barriers.txt Computer Architecture: A Quantitative Approach amazon.com/Computer-Architecture-Quantitative-Approach-4th/dp/0123704901/ref=dp_ob_title_bk

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• Hybrid EAV/CR model via WCF (and statically-typed language)?

  - by Pat

  Background I'm working on the architecture for a cloud-based LOB application, using Silverlight for the client, WCF, ASP.NET/C# for server and SQL Server for storage. The data model requires some flexibility per user (ability to add custom properties and define validation rules for them, for example), and a hybrid EAV/CR persistence model on the server side will suit nicely. Problem I need an efficient and maintainable technology and approach to handle the transformation from the persisted EAV model to/from WCF (and similarly allow the client to bind to the resulting data - DataGrid is a key UI element)? Admission: I don't yet know enough about WCF to understand if it supports ExpandoObject directly, but I suspect it will. Options I started off looking at WCF RIA services, but quickly discovered they're heavily dependent upon both static type data and compile-time code generation. Neither of these appeal. The options I'm considering include: Using WCF RIA services and pass the data over the network directly in EAV form (i.e. Dictionary), and handle the binding issue purely on the client side (like this) Using a dynamic language (probably IronPython) to handle both ends of the communication, with plumbing to generate the necessary CLR type data on the client to allow binding, and transform to/from EAV form on the server (spam preventer stopped me from posting a URL here, I'll try it in a comment). Dynamic LINQ (CreateClass() and friends), although I'm way out of my depth there and don't know what the limitations on that approach might be yet. I'm interested in comments on these approaches as well as alternative approaches that might solve the problem. Other Notes The Silverlight client will not be the only consumer of the service, making me slightly uncomfortable with option #1 above. While the data model is flexible, it's not expected to be modified heavily. For argument's sake, we could assume that we might have 25 distinct data models active at a given time, with something like 10-20 unique data fields/rules each. Modifications to the data model will happen infrequently (typically when a new user is initially configured).

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• How to solve timing problems in automated UI tests with C# and Visual Studio?

  - by Lernkurve

  Question What is the standard approach to solve timing problems in automated UI tests? Concrete example I am using Visual Studio 2010 and Team Foundation Server 2010 to create automated UI tests and want to check whether my application has really stopped running: [TestMethod] public void MyTestMethod() { Assert.IsTrue(!IsMyAppRunning(), "App shouldn't be running, but is."); StartMyApp(); Assert.IsTrue(IsMyAppRunning(), "App should have been started and should be running now."); StopMyApp(); //Pause(500); Assert.IsTrue(!IsMyAppRunning(), "App was stopped and shouldn't be running anymore."); } private bool IsMyAppRunning() { foreach (Process runningProcesse in Process.GetProcesses()) { if (runningProcesse.ProcessName.Equals("Myapp")) { return true; } } return false; } private void Pause(int pauseTimeInMilliseconds) { System.Threading.Thread.Sleep(pauseTimeInMilliseconds); } StartMyApp() and StopMyApp() have been recorded with MS Test Manager 2010 and reside in UIMap.uitest. The last assert fails because the assertion is executed while my application is still in the process of shutting down. If I put a delay after StopApp() the test case passes. The above is just an example to explain my problem. What is the standard approach to solve these kinds of timing issues? One idea would be to wait with the assertion until I get some event notification that my app has been stopped.

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• Movies recommendation engine conceptual database design

  - by Supyxy

  I am working at an movie recommendations engine and i'm facing a DB design issue. My actual database looks like this: MOVIES [ID,TITLE] KEYWORDS_TABLE [ID,KEY_ID] - where ID is Foreign Key for MOVIES.id and KEY_ID is a key for a text keywords table This is not the entire DB, but i showed here what's important for my problem. I have about 50,000 movies and about 1,3 milion keywords correlations, and basically my algorithm consists in extracting all the who have the same keywords with a given movie, then ordering them by the number of keywords correlations. For example i looked for a movie similar to 'Cast away' and it returned 'Six days and six nights' because it had the most keywords correlations (4 keywords): Island Airplane crash Stranded Pilot The algorithm is based on more factors, but this one is the most important and the most difficult for the approach. Basically what i do now is getting all the movies that have at least one keyword similar to the given movie and then ordering them by other factors which are not important for a moment. There wouldn't be any problem if there weren't so many records, a query lasts in many cases up to 10-20 seconds and some of them return even over 5000 movies. Someone already helped me on here (thanks Mark Byers) with optimizing the query but that's not enough because it takes too longer SELECT DISTINCT M.title FROM keywords_table K1 JOIN keywords_table K2 ON K2.key_id = K1.key_id JOIN movies M ON K2.id = M.id WHERE K1.id = 4 So i thought it would be better if i pre-made those lists with movies recommendations for each movie, but i'm not sure how to design the tables.. whatever is it a good idea or how would you take this approach?

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• OpenCV shape matching

  - by MAckerman

  I'm new to OpenCV (am actually using Emgu CV C# wrapper) and am attempting to do some object detection. I'm attempting to determine if an object matches a predefined set of objects (that I will have to define). The background is well lit and does not move. My objects that I am starting with are bottles and cans. My current approach is: Do absDiff with a previously taken background image to separate the background. Then dilate 4x to make the lighter areas (in labels) shrink. Then I do a binary threshold to get a big blog, followed by finding contours in this image. I then take the largest contour and draw it, which becomes my shape to either save to the accepted set or compare with the accepted set. Currently I'm using cvMatchShapes, but the double return value seems to vary widely. I'm guessing it is because it doesn't take into account rotation. Is this approach a good one? It isn't working well for glass bottles since the edges are hard to find... I've read about haar classifiers, but thinking that might be overkill for my task.

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