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• Input validation in WPF

  - by irfanali-wpfexpert

  i am developing an application in wpf using MVVM design pattern. i have a listbox when an item is slected then a dialog is open having the same record in editable mode. this dialog is binded with the selected item of the list. i have apply the validation rule for textbox using IDataErrorInfo. when the user update a record on dialogbox then at every key press, the selected record in listbox is also changed. if the user press save button then i submit changes to database. but if user click cancel button then i do not submit changes to database but the list box is updated with the current updation in GUI. when i refresh the list then old value appears again. My requirement is to update the listbox only when the user hit the save button but not on every key press on dialog box. I first fill the generic list with the linq to sql classes then bind the listbox with it. Please let me know what i have to do. Thanks in advance

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• How to tell what name RIA Services/EF Model uses for Associations?

  - by Nick Gotch

  Hi, I'm working on a C#.NET 3.5 WCF RIA Services app and having an issue with my Entity Framework model. My entity Foo is mapped to a DB table and has a primary key called FooId. My Bar is mapped to a DB view. I've selectively designed this view to generate a composite key in the EF using two of the columns (by making sure they were non-nullable and the others are all nullable. This was done using NULLIF and ISNULL in the view design.) I'm able to add this view to the model with no problem but I keep running into an issue when I try to map an association between the two. Foo should contain many Bars but I keep getting the following error when I add the association: Unable to retrieve AssociationType for association 'FK_Bar_Foo' According to this page, it looks like this might work if I can properly name the association (since RIA Services looks for specific names.) I've tried several variants of names that match the pattern of other associations with no success. Does anyone know if there's a place I can look to find out what name it's looking for? Thanks,

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• Caching a column in a polymorphic relationship

  - by Brendon Muir

  I have content management system application that uses a polymorphic tree table as the core of its arrangement. I've come into a problem where once the tree grows quite large, and because we have quite a few different modules (about 25), just doing :include = :instance doesn't cut the mustard. Instance is the name of our polymorphic relationship. The funny part is that in most cases when I want a large list of these items, all I really want is their name from the associated table (for the purposes of an index bar for example), all the rest is in the central table. So I thought that I should probably implement some sort of column cache for the name in the central table. (Like a counter cache that rails already does). I was just wondering if a plugin exists to manage this already? If not, I was just going to add a 'name' column to the central table and because all the polymorphic models inherit off a superclass, just add a callback that pushes the name across to the central table whenever the item is created or updated. I'd then just do a big migration to populate it in the first place? Any flaws to that design? I suppose to be more flexible the column could be some kind of serialised cache where I could store other things later on if need be? Gah! :D

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• I do I iterate the records in a database using LINQ when I have already built the LINQ DB code?

  - by Seth Spearman

  I asked on SO a few days ago what was the simplest quickest way to build a wrapper around a recently completed database. I took the advice and used sqlmetal to build linq classes around my database design. Now I am having two problems. One, I don't know LINQ. And, two, I have been shocked to realize how hard it is to learn. I have a book on LINQ (Linq In Action by Manning) and it has helped some but at the end of the day it is going to take me a couple of weeks to get traction and I need to make some progress on my project today. So, I am looking for some help getting started. Click HERE To see my simple database schema. Click HERE to see the vb class that was generated for the schema. My needs are simple. I have a console app. The main table is the SupplyModel table. Most of the other tables are child tables of the SupplyModel table. I want to iterate through each of Supply Model records. I want to grab the data for a supply model and then DoStuff with the data. And I also need to iterate through the child records, for each supply model, for example the NumberedInventories and DoStuff with that as well. I want to only iterate the SupplyModels that are have IDs that are in an array of strings containing the IDs. I need help doing this in VB rather than C# if possible. Thanks for your help. Seth

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• Place the business logic in Java Beans?

  - by Lirik

  I was reading this page and I found the following statement: MVC in Java Server Pages Now that we have a convenient architucture to separate the view, how can we leverage that? Java Server Pages (JSP) becomes more interesting because the HTML content can be separated from the Java business objects. JSP can also make use of Java Beans. The business logic could be placed inside Java Beans. If the design is architected correctly, a Web Designer could work with HTML on the JSP site without interfering with the Java developer. Interestingly in my textbook I pulled the following quote: In the MVC architecture... the original request is always handled by a servlet. The servlet invokes the business logic and data access code and creates beans to represent the results (that’s the model). Then, the servlet decides which Java Server Page is appropriate to present those particular results and forwards the request there (the JSP is the view). The servlet decides what business logic code applies and which JSP should present the results (the servlet is the controller). The two statements seem slightly contradicting. What is the best way to use beans: should we place business logic in them or should we only place results in them? Are there ways in which beans are inadequate for representing a model?

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• Why Java language does not offer a way to declare getters and setters of a given "field" through ann

  - by zim2001

  I actually happily design and develop JEE Applications for quite 9 years, but I realized recently that as time goes by, I feel more and more fed up of dragging all these ugly bean classes with their bunch of getters and setters. Considering a basic bean like this : public class MyBean { // needs getter AND setter private int myField1; // needs only a getter, no setter private int myField2; // needs only a setter, no getter private int myField3; /** * Get the field1 * @return the field1 */ public int getField1() { return myField1; } /** * Set the field1 * @param value the value */ public void setField1(int value) { myField1 = value; } /** * Get the field2 * @return the field2 */ public int getField2() { return myField2; } /** * Set the field3 * @param value the value */ public void setField3(int value) { myField3 = value; } } I'm dreaming of something like this : public class MyBean { @inout(public,public) private int myField1; @out(public) private int myField2; @in(public) private int myField3; } No more stupid javadoc, just tell the important thing... It would still be possible to mix annotation and written down getters or setters, to cover cases when it should do non-trivial sets and gets. In other words, annotation would auto-generate the getter / setter code piece except when a literate one is provided. Moreover, I'm also dreaming of replacing things like that : MyBean b = new MyBean(); int v = b.getField1(); b.setField3(v+1); by such : MyBean b = new MyBean(); int v = b.field1; b.field3 = v+1; In fact, writing "b.field1" on the right side of an expression would be semantically identical to write "b.getField1()", I mean as if it has been replaced by some kind of a preprocessor. It's just an idea but I'm wondering if I'm alone on that topic, and also if it has major flaws. I'm aware that this question doesn't exactly meet the SO credo (we prefer questions that can be answered, not just discussed) so I flag it community wiki...

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• Modularity in Flex

  - by Fernando

  I'm working on a pretty big application for Flex/Air. We are using GraniteDS and Tide to interact with the model from our Java EE server. I've been reading about modularization and Modules in Flex. The application has already been built, and I'm figuring a way out to re-design some classes and parts. From what I've read so far, I understand a Module is a different swf which can be dynamically load. Most of the tutorials/documentation are oriented to Flash "programmers" who are using Flex or Air instead of real developers, so that makes online resources harder to get. What I can't understand - yet - is how to encapsulate ActionScript classes or MXML views under this module. I've separated some of the code into libraries. For example, the generated code from Granite is in a "server" library. But I would like to separate parts of the logic with its Moderators, Controllers and Views. Are modules the way to go? Is there a "modules for dummies" or "head first Flex Modules for programmers" like tutorial in order to get a better perspective in order to build my architecture? When to choose libraries and when to choose modules? I'm using Flex 3.5, and a migration to Flex 4 is way far into the future, so no Flex 4 answers please, thanks!

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• How do people know so much about programming?

  - by Luciano

  I see people in this forums with a lot of points, so I assume they know about a lot of different programming stuff. When I was young I knew about basic (commodore) and the turbo pascal (pc). Then in college I learnt about C, memory management, x86 set, loop invariants, graphs, db query optimization, oop, functional, lambda calculus, prolog, concurrency, polymorphism, newton method, simplex, backtracking, dynamic programming, heuristics, np completeness, LR, LALR, neural networks, static & dynamic typing, turing, godel, and more in between. Then in industry I started with Java several years ago and learnt about it, and its variety of frameworks, and also design patterns, architecture patterns, web development, server development, mobile development, tdd, bdd, uml, use cases, bug trackers, process management, people management if you are a tech lead, profiling, security concerns, etc. I started to forget what I learnt in college... And then there is the stuff I don't know yet, like python, .net, perl, JVM stuff like groovy or scala.. Of course Google is a must for rapid documentation access to know if a problem has been solved already and how, and to keep informed about new stuff by blogs and places like this one. It's just too much or I just have a bad memory.. how do you guys manage it?

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• Storing URLs while Spidering

  - by itemio

  I created a little web spider in python which I'm using to collect URLs. I'm not interested in the content. Right now I'm keeping all the visited URLs in a set in memory, because I don't want my spider to visit URLs twice. Of course that's a very limited way of accomplishing this. So what's the best way to keep track of my visited URLs? Should I use a database? * which one? MySQL, sqlite, postgre? * how should I save the URLs? As a primary key trying to insert every URL before visiting it? Or should I write them to a file? * one file? * multiple files? how should I design the file-structure? I'm sure there are books and a lot of papers on this or similar topics. Can you give me some advice what I should read?

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• How do I develop browser plugins with cross-platform and cross-browser compatibility in mind?

  - by Schnapple

  My company currently has a product which relies on a custom, in-house ActiveX control. The technology it employs (TWAIN) is itself cross-platform by design, but our solution is obviously limited to Internet Explorer on Windows. Long term we would like to become cross-browser and cross-platform (i.e., support other browsers on Windows, support the Macintosh or Linux). Obviously if we wanted to support Firefox on Windows I would need to write a plugin for it. But if we wanted to support the Macintosh, how do I attack that? Is it possible to compile a version of the Firefox plugin that runs on the Mac? Would I be remiss to not also support Safari on the Mac? Are there any plugins which are cross-browser on a platform? (i.e., can any browsers run plugins for other browsers) Since TWAIN is so low-level to the operating system, I do not think Java would be a solution in any capacity, but I could be wrong. What do people generally do when they want to support multiple platforms with a process that will need to be cross-platform and cross-browser compatible?

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• Memory mapped files and "soft" page faults. Unavoidable?

  - by Robert Oschler

  I have two applications (processes) running under Windows XP that share data via a memory mapped file. Despite all my efforts to eliminate per iteration memory allocations, I still get about 10 soft page faults per data transfer. I've tried every flag there is in CreateFileMapping() and CreateFileView() and it still happens. I'm beginning to wonder if it's just the way memory mapped files work. If anyone there knows the O/S implementation details behind memory mapped files I would appreciate comments on the following theory: If two processes share a memory mapped file and one process writes to it while another reads it, then the O/S marks the pages written to as invalid. When the other process goes to read the memory areas that now belong to invalidated pages, this causes a soft page fault (by design) and the O/S knows to reload the invalidated page. Also, the number of soft page faults is therefore directly proportional to the size of the data write. My experiments seem to bear out the above theory. When I share data I write one contiguous block of data. In other words, the entire shared memory area is overwritten each time. If I make the block bigger the number of soft page faults goes up correspondingly. So, if my theory is true, there is nothing I can do to eliminate the soft page faults short of not using memory mapped files because that is how they work (using soft page faults to maintain page consistency). What is ironic is that I chose to use a memory mapped file instead of a TCP socket connection because I thought it would be more efficient. Note, if the soft page faults are harmless please note that. I've heard that at some point if the number is excessive, the system's performance can be marred. If soft page faults intrinsically are not significantly harmful then if anyone has any guidelines as to what number per second is "excessive" I'd like to hear that. Thanks.

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• Hiring a programmer: looking for the "right attitude"

  - by Totophil

  It's actually two questions in one: What is the right attitude for a programmer? How do you (or would you) look for one when interviewing or during hiring process? Please note this question is not about personality or traits of a candidate, it is about their attitude towards what they do for living. This is also not about reverse of programmers pet peeves. The question has been made community wiki, since I am interested in a good answer rather than reputation. I disagree that the question is purely subjective and just a matter of opinion: clearly some attitudes make a better programmer than others. Consecutively, there might quite possibly exist an attitude that is common to the most of the better programmers. Update: After some deliberation I came up with the following attitude measurement scales: identifies themselves with the job ? fully detached perceives code as a collection of concepts ? sees code as a sequence of steps thinks of creating software as an art ? takes 100% rational approach to design and development Answers that include some sort of a comment on the appropriateness of these scales are greatly appreciated. Definition of "attitude": a complex mental state involving beliefs and feelings and values and dispositions to act in certain ways; "he had the attitude that work was fun" The question came as a result of some reflection on the top voted answer to "How do you ensure code quality?" here on Stack Overflow.

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• Ruby or Rails reporting tools?

  - by Anushank

  I am looking for a report generation tool in ruby or rails which allows the user to define a template, then fetch data into the created template. I have been looking through "The Ruby Box: reporting section." There are two reporting tools I have looked at: Thin Reports: It is really good. You can create your own report template with the template editor. Then you can produce PDF reports using thinreports gems. ODF Report: You can create a template ODF file using Open Office and MS Word, and you can use that template to generate the report. Both of these solutions lack the ability to draw charts. Does anyone know of similar reporting tools that can draw charts within a given report? I have tried the RTF Ruby Library. It works, but shares the limitation that it cannot draw charts and graphs. The minimum requirements are: Able to create customizable templates. (e.g. design layout, set font size, color, embed images etc.) Able to draw tables and charts. Template could be in Docx or excel or xml or any other common file format. Report output report must be in Docx or RTF format. Thanks

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• How to build n-layered web architecture with PHP?

  - by Alex

  I have a description and design of a website and I need to redesign it to allow for new requirements. The website's purpose is the offering of government's contracts and bidding opportunities for different businesses.I'm dealing with the 3-tier architecture PHP website comprising of the user-interface tier(client's web browser),business logic layer(Apache web server with PHP engine in it and a couple of applications running within a web server as well) and a database layer(local mysql database). Now,i need to redesign it to su???rt distributed n-tier architecture and specify how I would go about it.After long hours of research i came to this solution: business logic should be separated into presentation and purely business logic tier to allow for n-layer architecture(user-interface,presentation tier,b.logic and data tier).I have decided to use ??? just for the presentation(since the original existing website is in PHP) and use it within apache web server.In the business logic i want to use J2?? implementation technology instead of implementing it in PHP(i.e using Zend app.server and smarty template) cz J2EE can provide much more essential container services which are essential for business logic,its robustness,maintainability and different critical business operations which will be carried out by the g?v?rnment's website.So,particularly,i want to use J??ss app.server with ?J? business objects in it which would provide all the b.logic in java and would interact with the database and so forth.In order to connect PHP on a web server with java on app.server i'm gonna use PHP/Java bridge API (or maybe Quercus or SOAP is better?).Finally,i have my data tier with mysql which will communicate with b.logic via JD??.Payment system application in ???.server is gonna use S??? to talk with credit card company. From your professional point of view,does it sound like a good way of redesigning the original website to allow for n-tier architecture considering the specifics of the website and the criticality of its operations?(payment system is included in it)or u would personally prefer to use PHP business objects for business logic as well instead of J2EE?If you have any wiser recommendation or some alternative,please let me know what is right or wrong in my current solution. H??? to hear your professional advice very s??n (I'm new to the area of web development) Thanks in advance

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• F# Active Pattern List.filter or equivalent

  - by akaphenom

  I have a records of types type tradeLeg = { id : int ; tradeId : int ; legActivity : LegActivityType ; actedOn : DateTime ; estimates : legComponents ; entryType : ShareOrDollarBased ; confirmedPrice: DollarsPerShare option; actuals : legComponents option ; type trade = { id : int ; securityId : int ; ricCode : string ; tradeActivity : TradeType ; enteredOn : DateTime ; closedOn : DateTime ; tradeLegs : tradeLeg list ; } Obviously the tradeLegs are a type off of a trade. A leg may be settled or unsettled (or unsettled but price confirmed) - thus I have defined the active pattern: let (|LegIsSettled|LegIsConfirmed|LegIsUnsettled|) (l: tradeLeg) = if Helper.exists l.actuals then LegIsSettled elif Helper.exists l.confirmedPrice then LegIsConfirmed else LegIsUnsettled and then to determine if a trade is settled (based on all legs matching LegIsSettled pattern: let (|TradeIsSettled|TradeIsUnsettled|) (t: trade) = if List.exists ( fun l -> match l with | LegIsSettled -> false | _ -> true) t.tradeLegs then TradeIsSettled else TradeIsUnsettled I can see some advantages of this use of active patterns, however i would think there is a more efficient way to see if any item of a list either matches (or doesn't) an actie pattern without having to write a lambda expression specifically for it, and using List.exist. Question is two fold: is there a more concise way to express this? is there a way to abstract the functionality / expression (fun l - match l with | LegIsSettled - false | _ - true) Such that let itemMatchesPattern pattern item = match item with | pattern -> true | _ -> false such I could write (as I am reusing this design-pattern): let curriedItemMatchesPattern = itemMatchesPattern LegIsSettled if List.exists curriedItemMatchesPattern t.tradeLegs then TradeIsSettled else TradeIsUnsettled Thoughts?

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• How do I detect whether the sample supplied by VideoSink.OnSample() is right-side up?

  - by Ken Smith

  We're currently using the Silverlight VideoSink to capture video from users' local webcams, kinda like so: protected override void OnSample(long sampleTime, long frameDuration, byte[] sampleData) { if (FrameShouldBeSubmitted()) { byte[] resampledData = ResizeFrame(sampleData); mediaController.SetVideoFrame(resampledData); } } Now, on most of the machines that we've tested, the video sample provided in the byte[] sampleData parameter is upside-down, i.e., if you try to take the RGBA data and turn it into, say, a WriteableBitmap, the bitmap will be upside-down. That's odd, but fairly easy to correct, of course -- you just have to reverse the array as you encode it. The problem is that at least on some machines (e.g., the single Macintosh in our test environment), the video sample provided is no longer upside-down, but right-side up, and hence, flipping the image actually results in an image that's received upside-down on the far side. I reported this to MS as a bug, but their (terse) response was that it was "As Designed". Further attempts at clarification have so far been ignored. Now, I'll grant that it's kinda entertaining to imagine the discussions behind this design decision: "OK, just to make it interesting, let's play the video rightside up on a Mac, but let's turn it upside down for Windows!" "Great idea!" "Yeah, that'll keep those developers guessing!" But beyond that, I can't find this, umm, "feature" documented anywhere, nor can I find any documentation on how one is supposed to be able to tell that a given video sample is upside down or rightside up. Any thoughts on how to tell this?

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• Difficulties using custom control - RichTextEditor

  - by Chris

  I am working on a school project that uses ASP.NET. I found this TextEditor control ( http://blogs.msdn.com/kirti/archive/2007/11/10/rich-text-editor-is-here.aspx ) that I am trying to include but it isn't working. The error I am getting is: Error Rendering Control - TextEditor. An unhandled exception has occurred. Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index. I see this error when I go Design part of the editor. I just don't understand this error at all. Also I am a lil bit confused as there is no parameter called index. :( What I have done is reference the binary in my project and then on the page I am trying to use it have registered its namespace and assembly with this line: <%@ Register Assembly="RichTextEditor" Namespace="AjaxControls" TagPrefix="rtt" %> I then go ahead and try to add the control to the page with this line of code: <rtt:richtexteditor ID="TextEditor" Theme="Blue" runat="server" /> Any help would be much appreciated. I haven't done anything like add a custom control before.

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• Non RBAC User Roles and Permissions System: checking the user's City

  - by micha12

  We are currently designing a User Roles and Permissions System in our web application (ASP.NET), and it seems that we have several cases that do no fit within the classical Role-Based Access Control (RBAC). I will post several questions, each devoted to a particular case, this being the first post. We have the following case: not to allow a user view a certain page if the user lives in a particular city. This is a simple case that is coded in the following way: if (User.City == “Moscow”) // Allow the user to view the page. else // Do not allow the user to view this page. Though this case is very simple and straightforward, it has nothing to do with the RBAC. On StackOverflow, someone called this an Attribute-based Access Control. Under the classical RBAC, it seems that this case should be designed like this: introduce a permission “City where the person lives”, this permission will have a property City. Then create a role, add a permission of type “City = Moscow” to it and the assign the role to the user. Looks extremely cumbersome. The question is whether it is acceptable to introduce such non-RBAC approaches to our permissions system – does that break the design or not? This might seem a primitive question, but we found that most applications use pure RBAC, and we started to think that we might be doing something wrong. Thank you.

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• SIMPLE PHP MVC Framework!

  - by Allen

  I need a simple and basic MVC example to get me started. I dont want to use any of the available packaged frameworks. I am in need of a simple example of a simple PHP MVC framework that would allow, at most, the basic creation of a simple multi-page site. I am asking for a simple example because I learn best from simple real world examples. Big popular frameworks (such as code ignighter) are to much for me to even try to understand and any other "simple" example I have found are not well explained or seem a little sketchy in general. I should add that most examples of simple MVC frameworks I see use mod_rewrite (for URL routing) or some other Apache-only method. I run PHP on IIS. I need to be able to understand a basic MVC framework, so that I could develop my own that would allow me to easily extend functionality with classes. I am at the point where I understand basic design patterns and MVC pretty well. I understand them in theory, but when it comes down to actually building a real world, simple, well designed MVC framework in PHP, i'm stuck. I would really appreciate some help! Edit: I just want to note that I am looking for a simple example that an experienced programmer could whip up in under an hour. I mean simple as in bare bones simple. I dont want to use any huge frameworks, I am trying to roll my own. I need a decent SIMPLE example to get me going.

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• Selectively suppress XML comments?

  - by Mike Post

  We deliver a number of assemblies to external customers, but not all of the public APIs are officially supported. For example, due to less than optimal design choices sometimes a type must be publicly exposed from an assembly for the rest of our code to work, but we don't want customers to use that type. One part of communicating the lack of support is not provide any intellisense in the form of XML comments. Is there a way to selectively suppress XML comments? I'm looking for something other than ignoring warning 1591 since it's a long term maintenance issue. Example: I have an assembly with public classes A and B. A is officially supported and should have XML documentation. B is not intended for external use and should not be documented. I could turn on XML documentation and then suppress warning 1591. But when I later add the officially supported class C, I want the compiler to tell me that I've screwed up and failed to add the XML documentation. This wouldn't occur if I had suppressed 1591 at the project level. I suppose I could #pragma across entire classes, but it seems like there should be a better way to do this.

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• MSN Messenger API

  - by MarceloRamires

  back when I was not working with programming (using skills from courses and school) I started developing a simple program that is supposed to get the Artwork of the album to which the song you're currently listening in iTunes to and set it as you Display Picture in MSN Messenger (everything had to be open at the same time). I was so excited about it, made it as nicely as I could back then (now I consider it a design and usability complete fail), and it surprisingly worked. Now, a couple of versions ahead (MSN from 8.5 to 9.0, iTunes from 8 to 9, and windows from Vista to 7) I am getting some incompatibility issues. Where I work, I use Windows 7, Windows Live Messenger 2009 and iTunes 9 - it works just just like before, but at home I have the same exact setup, but something weird happens: When I open the program (having my itunes AND msn open) it doesn't use the active MSN instance, instead it opens a new one, and doesn't work even on this opened one. I've tried it with a couple of libraries: Interop.Messenger.dll - workis like described above Interop.MessengerAPI.dll - works like described above Interop.MessengerPrivate.dll - never worked MSNMessenger.dll - the one I used before - doesn't work anymore at all What could I do ? Info: Visual Studio 2008, .NET 3.5, C#, WinForms application. I'll watch this question and add any information if requested

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• Visual Studio 2005 - OleDbConnection throws "Invalid authorization specification" in Form Designer,

  - by Jason Dagit

  I have a form with an OleDbConnection object on it. This form fails to load in the Form Designer with the message: One or more errors encountered while loading the designer. The errors are listed below. Some errors can be fixed by rebuilding your project, while others may require code changes. Invalid authorization specification at ADODB.ConnectionClass.Open(String ConnectionString, String UserID, String Password, Int32 Options) ... (stack trace continues into user code) I've tracked this down to the OleDbConnection string. If I hardcode in the server IP, username/password/dbinstance into the constructor of the GUI form then the form will load in the designer. At run-time it is not an issue because we require the user to provide the login details. The question: Is it possible to use the OleDbConnection and the Form designer without supplying the database credentials in the source code of the form? For example, is there a property of the OleDbConnection or Form that I can set so that it doesn't need to access the database during Form design? My concern is that if we ever move the database server or change the login that the code will stop working in the designer.

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• What is a good standard exercise to learn the OO features of a language?

  - by FarmBoy

  When I'm learning a new language, I often program some mathematical functions to get used to the control flow syntax. After that, I like to implement some sorting algorithms to get used to the array/list constructs. But I don't have a standard exercise for exploring the languages OO features. Does anyone have a stock exercise for this? A good answer would naturally lend to inheritance, polymorphism, etc., for a programmer already comfortable with these concepts. An ideal answer would be one that could be communicated in a few words, without ambiguity, in the way that "implement mergesort" is completely unambiguous. (As an example, answering "design a game" is so vague as to be useless.) Any ideas? EDIT: I have to remark that the results here are somewhat ironic. 10 upvotes and (originally) 5 favorites suggest that this is a question others are interested in. Yet the most upvoted answer is one that says there is no good answer. Oh well. I think I'll look at the textbook below, I've found games useful in the past for OO.

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• traversal of multiple separate web services in a ring network

  - by qkrsppopcmpt

  I am facing a design problem, here is some basic requirement: Aggregator 1. Separate service for blog,video,images and associations. 2. Each of the service should be completely separate, that means they run on separate tomcat. 3. And each aggregator must be able to query local database and other aggregators 4. Traversal of services must be asynchronous using a ring network. For example, we have a ring like ws1-ws2-ws3-ws4-ws1. Each node represents one type of one aggregator. The traveral goes in this way: the query from ws1 to ws2, and ws1 is waiting for the response from ws2 asynchronously; ws2 to ws3, also ws2 wait for ws3 asynchronously. If ws3 has the data, reply to ws2 then to ws1, then reply. However if ws3 goes away, the traversal should go back to ws2, then to ws1, then go to ws4, then go to ws3 again. then tells ws4 since ws3 fails. The required technology is axis2 and tomcat 6. Does anybody have any clue about it? If it is clear, I can clarify the question more clearly. Thanks very much.

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• Flex 3 - Scroll bar issue

  - by Emma

  Im currently learning Flex, and Im having the hardest time getting scroll bars to work. In short Im pretty much just making a giant form for users to fill out, contained within a viewstack component, the user will type up information in one view, and it will be displayed in the other. But right now in the first canvas i have components that run of the screen and flex doesnt seem to automate a scroll bar, so i added in 'verticalScrollPolicy="on"' to my canvas, now while it gives me a scroll bar, it gives me an empty scroll bar, I still cannot move it up or down, meaning components are still trapped off the bottom of my screen. Im I missing something amazingly simple? Edit - Sorry, Im using Adobe Flex Builder 3, and the components it lets you drag in. http://img12.imageshack.us/img12/218/problem1f.jpg This is a picture of the problem, and i guess relavent code would be. <mx:Application xmlns:mx="adobe.com/2006/mxml"; layout="absolute" width="830" height="835"> <mx:ViewStack x="10" y="72" id="viewstack1" width="790" height="751" > <mx:Canvas label="Design Mode" width="100%" height="100%" verticalScrollPolicy="on" horizontalScrollPolicy="on" > (Components inside) </mx:Canvas> Sorry if Im using this site wrong, still very new

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