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• Why do many software projects fail today?

  - by TomTom

  As long as there are software projects, the world is wondering why they fail so often. I would like to know if there is a list or something equivalent which shows how many software projects fail today. Would be nice if there would be a comparison over the last 20 - 30 years. You can also add your top reason why a software project fails. Mine is "Requirements are poor or not even existing." which includes also "No (real) customer / user involved". EDIT: It is nearly impossible to clearly define the term "fail". Let's say that fail means: The project was more than 10% over budget and time. In my opinion the 10% + / - is a good range for an offer / tender. EDIT: Until now (Feb 11) it seems that most posters agree that a fail of the project is basically a failure of the project management (whatever fail means). But IMHO it comes out, that most developers are not happy with this situation. Perhaps because not the manager get penalized when a project was not successful, but the lazy, incompetent developer teams? When I read the posts I can also hear-out that there is a big "gap" between the developer side and the managment side. The expectations (perhaps also the requirements) seem to be so different, that a project cannot be successful in the end (over time / budget; users are not happy; not all first-prio features implemented; too many bugs because developers were forced to implement in too short timeframes ...) I',m asking myself: How can we improve it? Or do we have the possibility to improve it? Everybody seems to be unsatisfied with the way it goes now. Can we close the gap between these two worlds? Should we (the developers) go on strike and fight for "high quality reqiurements" and "realistic / iteration based time shedules"? EDIT: Ralph Westphal and Stefan Lieser have founded a new "community" called: Clean-Code-Developer. The aim of the group is to bring more professionalism into software engineering. Independently if a developer has a degree or tons of years of experience you can be part of this movement. Clean Code Developers live principles like SOLID every day. A professional developer is the biggest reviewer of his own work. And he has an internal value system which helps him to improve and become better. Check it out on: Clean Code Developer EDIT: Our company is doing at the moment a thing called "Application Development and Maintenance Benchmarking". This is a service offered by IBM to get a feedback from someone external on your software engineering process quality etc. When we get the results, I will tell you more about it.

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• Ajax call to wcf windows service over ssl (https)

  - by bpatrick100

  I have a windows service which exposes an endpoint over http. Again this is a windows service (not a web service hosted in iis). I then call methods from this endpoint, using javascript/ajax. Everything works perfectly, and this the code I'm using in my windows service to create the endpoint: //Create host object WebServiceHost webServiceHost = new WebServiceHost(svcHost.obj, new Uri("http://192.168.0.100:1213")); //Add Https Endpoint WebHttpBinding binding = new WebHttpBinding(); webServiceHost.AddServiceEndpoint(svcHost.serviceContract, binding, string.Empty); //Add MEX Behaivor and EndPoint ServiceMetadataBehavior metadataBehavior = new ServiceMetadataBehavior(); metadataBehavior.HttpGetEnabled = true; webServiceHost.Description.Behaviors.Add(metadataBehavior); webServiceHost.AddServiceEndpoint(ServiceMetadataBehavior.MexContractName, MetadataExchangeBindings.CreateMexHttpBinding(), "mex"); webServiceHost.Open(); Now, my goal is to get this same model working over SSL (https not http). So, I have followed the guidance of several msdn pages, like the following: http://msdn.microsoft.com/en-us/library/ms733791(VS.100).aspx I have used makecert.exe to create a test cert called "bpCertTest". I have then used netsh.exe to configure my port (1213) with the test cert I created, all with no problem. Then, I've modified the endpoint code in my windows service to be able to work over https as follows: //Create host object WebServiceHost webServiceHost = new WebServiceHost(svcHost.obj, new Uri("https://192.168.0.100:1213")); //Add Https Endpoint WebHttpBinding binding = new WebHttpBinding(); binding.Security.Mode = WebHttpSecurityMode.Transport; binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.Certificate; webServiceHost.AddServiceEndpoint(svcHost.serviceContract, binding, string.Empty); webServiceHost.Credentials.ServiceCertificate.SetCertificate("CN=bpCertTest", StoreLocation.LocalMachine, StoreName.My); //Add MEX Behaivor and EndPoint ServiceMetadataBehavior metadataBehavior = new ServiceMetadataBehavior(); metadataBehavior.HttpsGetEnabled = true; webServiceHost.Description.Behaviors.Add(metadataBehavior); webServiceHost.AddServiceEndpoint(ServiceMetadataBehavior.MexContractName, MetadataExchangeBindings.CreateMexHttpsBinding(), "mex"); webServiceHost.Open(); The service creates the endpoint successfully, recognizes my cert in the SetCertificate() call, and the service starts up and running with success. Now, the problem is my javascript/ajax call cannot communicate with the service over https. I simply get some generic commication error (12031). So, as a test, I changed the port I was calling in the javascript to some other random port, and I get the same error - which tells me that I'm obviously not even reaching my service over https. I'm at a complete loss at this point, I feel like everything is in place, and I just can't see what the problem is. If anyone has experience in this scenario, please provide your insight and/or solution! Thanks!

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• Long-running ASP.NET tasks

  - by John Leidegren

  I know there's a bunch of APIs out there that do this, but I also know that the hosting environment (being ASP.NET) puts restrictions on what you can reliably do in a separate thread. I could be completely wrong, so please correct me if I am, this is however what I think I know. A request typically timeouts after 120 seconds (this is configurable) but eventually the ASP.NET runtime will kill a request that's taking too long to complete. The hosting environment, typically IIS, employs process recycling and can at any point decide to recycle your app. When this happens all threads are aborted and the app restarts. I'm however not sure how aggressive it is, it would be kind of stupid to assume that it would abort a normal ongoing HTTP request but I would expect it to abort a thread because it doesn't know anything about the unit of work of a thread. If you had to create a programming model that easily and reliably and theoretically put a long running task, that would have to run for days, how would you accomplish this from within an ASP.NET application? The following are my thoughts on the issue: I've been thinking a long the line of hosting a WCF service in a win32 service. And talk to the service through WCF. This is however not very practical, because the only reason I would choose to do so, is to send tasks (units of work) from several different web apps. I'd then eventually ask the service for status updates and act accordingly. My biggest concern with this is that it would NOT be a particular great experience if I had to deploy every task to the service for it to be able to execute some instructions. There's also this issue of input, how would I feed this service with data if I had a large data set and needed to chew through it? What I typically do right now is this SELECT TOP 10 * FROM WorkItem WITH (ROWLOCK, UPDLOCK, READPAST) WHERE WorkCompleted IS NULL It allows me to use a SQL Server database as a work queue and periodically poll the database with this query for work. If the work item completed with success, I mark it as done and proceed until there's nothing more to do. What I don't like is that I could theoretically be interrupted at any point and if I'm in-between success and marking it as done, I could end up processing the same work item twice. I might be a bit paranoid and this might be all fine but as I understand it there's no guarantee that that won't happen... I know there's been similar questions on SO before but non really answers with a definitive answer. This is a really common thing, yet the ASP.NET hosting environment is ill equipped to handle long-running work. Please share your thoughts.

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• Problem with Google Analytics for Android : "Dispatcher thinks it finished, but there were 543 faile

  - by PHP_Jedi

  Anyone know how to solve this problem? 03-23 13:03:20.585: WARN/googleanalytics(3430): Problem with socket or streams. 03-23 13:03:20.585: WARN/googleanalytics(3430): java.net.SocketException: Broken pipe 03-23 13:03:20.585: WARN/googleanalytics(3430): at org.apache.harmony.luni.platform.OSNetworkSystem.sendStreamImpl(Native Method) 03-23 13:03:20.585: WARN/googleanalytics(3430): at org.apache.harmony.luni.platform.OSNetworkSystem.sendStream(OSNetworkSystem.java:498) 03-23 13:03:20.585: WARN/googleanalytics(3430): at org.apache.harmony.luni.net.PlainSocketImpl.write(PlainSocketImpl.java:585) 03-23 13:03:20.585: WARN/googleanalytics(3430): at org.apache.harmony.luni.net.SocketOutputStream.write(SocketOutputStream.java:59) 03-23 13:03:20.585: WARN/googleanalytics(3430): at org.apache.http.impl.io.AbstractSessionOutputBuffer.flushBuffer(AbstractSessionOutputBuffer.java:87) 03-23 13:03:20.585: WARN/googleanalytics(3430): at org.apache.http.impl.io.AbstractSessionOutputBuffer.flush(AbstractSessionOutputBuffer.java:94) 03-23 13:03:20.585: WARN/googleanalytics(3430): at org.apache.http.impl.AbstractHttpClientConnection.doFlush(AbstractHttpClientConnection.java:168) 03-23 13:03:20.585: WARN/googleanalytics(3430): at org.apache.http.impl.AbstractHttpClientConnection.flush(AbstractHttpClientConnection.java:173) 03-23 13:03:20.585: WARN/googleanalytics(3430): at com.google.android.apps.analytics.PipelinedRequester.sendRequests(Unknown Source) 03-23 13:03:20.585: WARN/googleanalytics(3430): at com.google.android.apps.analytics.NetworkDispatcher$DispatcherThread$AsyncDispatchTask.dispatchSomePendingEvents(Unknown Source) 03-23 13:03:20.585: WARN/googleanalytics(3430): at com.google.android.apps.analytics.NetworkDispatcher$DispatcherThread$AsyncDispatchTask.run(Unknown Source) 03-23 13:03:20.585: WARN/googleanalytics(3430): at android.os.Handler.handleCallback(Handler.java:587) 03-23 13:03:20.585: WARN/googleanalytics(3430): at android.os.Handler.dispatchMessage(Handler.java:92) 03-23 13:03:20.585: WARN/googleanalytics(3430): at android.os.Looper.loop(Looper.java:123) 03-23 13:03:20.585: WARN/googleanalytics(3430): at android.os.HandlerThread.run(HandlerThread.java:60) 03-23 13:03:21.088: WARN/googleanalytics(3430): Dispatcher thinks it finished, but there were 543 failed events Specially the last line explain why there is lost so much data, as the dispatcher thinks it is done, but have 543 events not dispatched... The application have a good internet connection and there is no problem reaching the app server-side api. I see in analytics that lots of startups and click-events the past few days are lost, even I know the traffic is normal since i can see statistics from the the server api. In the analytics reports I see a day by day under-reporting. So the problems seems to be spreading/growing to all the devices using this application. Im wondering why google does not answer this in their mail-groups - several people have complained about this...well, well... I found this thread relevant: http://stackoverflow.com/questions/682560/java-net-socketexception-broken-pipe But, I'm still not sure if there is anything I can do to fix it or not. If there is nothing I can do to fix it, I guess its not my fault that it got broken. But i got a feeling it is, since the problem got dramatically worse on the last deploy to Android market. Anyone else with experience on Google Analytics for android ?

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• Eventlet or gevent or Stackless + Twisted, Pylons, Django and SQL Alchemy

  - by Khorkrak

  We're using Twisted extensively for apps requiring a great deal of asynchronous io. There are some cases where stuff is cpu bound instead and for that we spawn a pool of processes to do the work and have a system for managing these across multiple servers as well - all done in Twisted. Works great. The problem is that it's hard to bring new team members up to speed. Writing asynchronous code in Twisted requires a near vertical learning curve. It's as if humans just don't think that way naturally. We're considering a mixed approach perhaps. Maybe do the xmlrpc server part and process management in Twisted still but the other stuff in code that at least looks synchronous while not being as such. Then again I like explicit over implicit so hmmm. Anyway onto greenlets - how well does that stuff work? So there's Stackless and as you can see from my Gallentean avatar I'm well aware of the tremendous success in it's use for CCP's flagship EVE Online game first hand. What about Eventlet or gevent? Well for now only Eventlet works with Twisted. However gevent claims to be faster since it's not a pure python implementation it instead uses libevent. It also has fewer idiosyncrasies and defects supposedly. The documentation there is minimal in comparison to Eventlet and it's maintained by 1 guy as far as I can tell. This makes me leery but all great projects start this way so... Then there's PyPy - I haven't even finished reading about that one yet - just saw it in this thread: Drawbacks of Stackless. So confusing - I'm wondering what the heck to do - sounds like Eventlet is probably the best bet but is it really stable enough? Anyone out there have any experience with it? Should we go with Stackless instead as it's been around and is proven technology - just like Twisted is as well - and they do work together nicely. But still I hate having to have a separate version of Python to do this. what to do.... This somewhat obnoxious blog entry hit the nail on the head for me though: Asynchronous IO for Grownups We're stuck using MySQL as well - I never knew how great PostgreSQL was until having had to work on a production OLTP system in MySQL instead - but that's another story. But if that monkey patch thing really works then wow. Just wow.

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• Delphi TBytesField - How to see the text properly - Source is HIT OLEDB AS400

  - by myitanalyst

  We are connecting to a multi-member AS400 iSeries table via HIT OLEDB and HIT ODBC. You connect to this table via an alias to access a specific multi-member. We create the alias on the AS400 this way: CREATE ALIAS aliasname FOR table(membername) We can then query each member of the table this way: SELECT * FROM aliasname We are testing this in Delphi6 first, but will move it to D2010 later We are using HIT OLEDB for the AS400. We are pulling down records from a table and the field is being seen as a tBytesField. I have also tried ODBC driver and it sees as tBytesField as well. Directly on the AS400 I can query the data and see readable text. I can use the iSeries Navigation tool and see readable text as well. However when I bring it down to the Delphi client via the HIT OLEDB or HIT ODBC and try to view via asString then I just see unreadable text.. something like this: ñðð@ðõñððððñ÷@õôððõñòøóóöøñðÂÁÕÒ@ÖÆ@ÁÔÅÙÉÃÁ@@@@@@@@ÂÈÙÉâãæÁðòñè@ÔK@k@ÉÕÃK@@@@@@@@@ç I jumbled up the text above, but that is the character types that show up. When I did a test in D2010 the text looks like japanse or chinese characters, but if I display as AnsiString then it looks like what it does in Delphi 6. I am thinking this may have something to do with code pages or character sets, but I have no experience in this are so it is new to me if it is related. When I look at the Coded Character Set on the AS400 it is set to 65535. What do I need to do to make this text readable? We do have a third party component (Delphi400) that makes things behave in a more native AS400 manner. When I use its AS400 connection and AS400 query components it shows the field as a tStringField and displays just fine. BUT we are phasing out this product (for a number of reasons) and would really like the OLEDB with the ADO components work. Just for clarification the HIT OLEDB with tADOQuery do have some fields showing as tStringFields for many of the other tables we use... not sure why it is showing as a tBytesField in this case. I am not an AS400 expert, but looking at the field definititions on the AS400 the ones showing up as tBytesField look the same as the ones showing up as tStringFields... but there must be a difference. Maybe due to being a multi-member? So... does anyone have any guidance on how to get the correct string data that is readable? If you need more info please ask. Greg

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• Focusable EditText inside ListView

  - by Joe

  I've spent about 6 hours on this so far, and been hitting nothing but roadblocks. The general premise is that there is some row in a ListView (whether it's generated by the adapter, or added as a header view) that contains an EditText widget and a Button. All I want to do is be able to use the jogball/arrows, to navigate the selector to individual items like normal, but when I get to a particular row -- even if I have to explicitly identify the row -- that has a focusable child, I want that child to take focus instead of indicating the position with the selector. I've tried many possibilities, and have so far had no luck. layout: <ListView android:id="@android:id/list" android:layout_height="fill_parent" android:layout_width="fill_parent" /> Header view: EditText view = new EditText(this); listView.addHeaderView(view, null, true); Assuming there are other items in the adapter, using the arrow keys will move the selection up/down in the list, as expected; but when getting to the header row, it is also displayed with the selector, and no way to focus into the EditText using the jogball. Note: tapping on the EditText will focus it at that point, however that relies on a touchscreen, which should not be a requirement. ListView apparently has two modes in this regard: 1. setItemsCanFocus(true): selector is never displayed, but the EditText can get focus when using the arrows. Focus search algorithm is hard to predict, and no visual feedback (on any rows: having focusable children or not) on which item is selected, both of which can give the user an unexpected experience. 2. setItemsCanFocus(false): selector is always drawn in non-touch-mode, and EditText can never get focus -- even if you tap on it. To make matters worse, calling editTextView.requestFocus() returns true, but in fact does not give the EditText focus. What I'm envisioning is basically a hybrid of 1 & 2, where rather than the list setting if all items are focusable or not, I want to set focusability for a single item in the list, so that the selector seamlessly transitions from selecting the entire row for non-focusable items, and traversing the focus tree for items that contain focusable children. Any takers?

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• Revisiting .NET, but what should I focus on?

  - by Wayne M

  After about a two-year hiatus, I'm brushing up on my .NET skills to find a .NET job (my previous two positions have very little development, or development using legacy technologies, so apart from a few very minor apps I have not touched .NET in close to two years). I'm aware of things like ASP.NET MVC, and I have previously read on things like NHibernate and DI/IOC, albeit I have yet to use them apart from very trivial "Hello World" type applications. I have a subscription to Rob Conery's Tekpub website and occasionally watch these videos when I have free time. My concern is this: I don't live in a very technical area. I would be surprised if any but the most tech-savvy companies have heard of, let alone use, ASP.NET MVC, NHibernate (or even LINQ/EF), or know about IoC. I would be willing to bet a large sum of money that 95% of the possible jobs I could obtain will use the following: Visual Source Safe, if any VCS at all ASP.NET 2.0 Webforms (3.5 if lucky) Raw ADO.NET on top of a very thin implementation of the Gateway pattern Stored Procedures in the database for most CRUD operations Gratuitous use of code-behind, with a Service layer if I'm lucky If I were extremely lucky, I might find a shop that has heard of ORMs and either uses one, or has wrote their own data abstraction. Also if I were lucky, the company would be using Model-View-Presenter. In light of this I'm not sure what I should focus on learning. Personally, I would prefer to be using the latest stuff - ASP.NET MVC, NHibernate, jQuery, WCF etc. Reality says I should go back to the basics, since it looks like most potential opportunities aren't going to be anywhere near the cutting edge, or anywhere close to it. And, as much as I would like to find a position and start to show the other developers the benefits, in my past experience this has usually resulted in my being fired for "not being a team player" and doing things the bad old way. So, I am curious how you would approach a situation like this? What should I focus on, in order to A) Reaquaint myself with .NET, and B) Prepare myself to obtain a .NET job again that is more than likely going to use techniques that I and most other knowledgeable developers will scoff at?

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• Android Mediaplayer: setDataSource issue for downloaded media file

  - by Erik

  I have an application that will record and play audio files. Some of the audio files are downloaded using simple standard http downloads using httpclient. It worked like a charm for a long time. Now all of a sudden I cannot play the files I download. It fails with this stack. I store the files on the SDCard and I experience the problem both on a handset and a USB connected device. I have checked that the downloaded file is cool on the server, and I can play it without any issues. These are the code snippets I use ( I know that recordingFile is a valid path for the file). // inside the activity class private void playRecording() throws IOException{ File recordingFile = new File(recordingFileName); FileInputStream recordingInputStream = new FileInputStream(recordingFile); audioMediaPlayer.playAudio(recordingInputStream); } Here is the media player code: // inside my media player class which handles the recordings public void playAudio(FileInputStream audioInputStream) throws IOException { mediaPlayer.reset(); mediaPlayer.setDataSource(audioInputStream.getFD()); mediaPlayer.prepare(); mediaPlayer.start(); } Here is the exception: E/MediaPlayerService( 555): offset error E/MediaPlayer( 786): Unable to to create media player W/System.err( 786): java.io.IOException: setDataSourceFD failed.: status=0x80000000 W/System.err( 786): at android.media.MediaPlayer.setDataSource(Native Method) W/System.err( 786): at android.media.MediaPlayer.setDataSource(MediaPlayer.java:632) W/System.err( 786): at net.xxx.xxx.AudioMediaPlayer.playAudio(AudioMediaPlayer.java:69) W/System.err( 786): at net.xxx.xxx.Downloads.playRecording(Downloads.java:299) W/System.err( 786): at net.xxx.xxx.Downloads.access$0(Downloads.java:294) W/System.err( 786): at net.xxx.xxx.Downloads$1.onClick(Downloads.java:135) I have tried seeking some answer of the offset error, but not really clear what this issue might be. PS I download the file with this code: public FileOutputStream executeHttpGet(FileOutputStream fileOutputStream) throws ClientProtocolException, IOException{ try { // Execute HTTP Post Request httpResponse = httpClient.execute(httpPost, localContext); int status = httpResponse.getStatusLine().getStatusCode(); // we assume that the response body contains the error message if (status != HttpStatus.SC_OK) { ByteArrayOutputStream ostream = new ByteArrayOutputStream(); httpResponse.getEntity().writeTo(ostream); fileOutputStream = null; } else { InputStream content = httpResponse.getEntity().getContent(); byte[] buffer = new byte[1024]; int len = 0; while ( (len = content.read(buffer)) > 0 ) { fileOutputStream.write(buffer,0, len); } fileOutputStream.close(); content.close(); // this will also close the connection } } catch (ClientProtocolException e1) { // TODO Auto-generated catch block e1.printStackTrace(); fileOutputStream = null; } catch (IOException e2) { // TODO Auto-generated catch block e2.printStackTrace(); fileOutputStream = null; } return fileOutputStream; }

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• Using GraphicsServices.h/GSEvent as well as compiling CLI iPhone tools with XCode

  - by Peter Hajas

  I sent this to KennyTM (has all the private framework headers on GitHub) but I figured I'd ask here too just in case someone has some good ideas or any way to help me out. I'm trying to write a command line utility that sends GSEvents to operate the keyboard, touch/drag elements onscreen, and operate hardware buttons (volume, home, sleep, etc.) I grabbed the MouseSupport code and tried to look through it, but I couldn't find the easiest way to send GSEvents. I'm hoping someone here can help me. First, what's the simplest way to declare a GSEvent and send it? I looked at the iPhone development wiki, but the documentation was very vague. I understand that there's a purple event port (?) that I have to send these events to, but I don't understand how to do that. Could someone offer examples for, say, touching at a coordinate, typing a certain key, or pressing a hardware button? Also, do I have to write or do anything special if I want this utility to operate all applications as well as Springboard? I don't know if this is a special case because I want it at the OS level. Ideally, I would SSH into the phone, start the program, and it would send GSEvents that would be handled by whatever application was open. As far as compiling this code, is there any way to do so under XCode? I don't know what sort of project template I should use (if any) and this is throwing me off. I don't need "build and go" support, I'm more than happy to scp the program over to the phone. I understand that compiling the code is also feasible on the phone. I have all of the headers from the SDK on my phone along with iphone-gcc, but when compiling some test programs I still get errors about not finding mach headers and CoreFoundation. Is there an easier way to do this? Lastly, are there other guides or pieces of literature that anyone can point me towards for learning more about this? I'm excited to get into open iPhone development (I have experience with the official SDK, but I want to go deeper). Thanks for any and all help people can offer!

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• C# Monte Carlo Incremental Risk Calculation optimisation, random numbers, parallel execution

  - by m3ntat

  My current task is to optimise a Monte Carlo Simulation that calculates Capital Adequacy figures by region for a set of Obligors. It is running about 10 x too slow for where it will need to be in production and number or daily runs required. Additionally the granularity of the result figures will need to be improved down to desk possibly book level at some stage, the code I've been given is basically a prototype which is used by business units in a semi production capacity. The application is currently single threaded so I'll need to make it multi-threaded, may look at System.Threading.ThreadPool or the Microsoft Parallel Extensions library but I'm constrained to .NET 2 on the server at this bank so I may have to consider this guy's port, http://www.codeproject.com/KB/cs/aforge_parallel.aspx. I am trying my best to get them to upgrade to .NET 3.5 SP1 but it's a major exercise in an organisation of this size and might not be possible in my contract time frames. I've profiled the application using the trial of dotTrace (http://www.jetbrains.com/profiler). What other good profilers exist? Free ones? A lot of the execution time is spent generating uniform random numbers and then translating this to a normally distributed random number. They are using a C# Mersenne twister implementation. I am not sure where they got it or if it's the best way to go about this (or best implementation) to generate the uniform random numbers. Then this is translated to a normally distributed version for use in the calculation (I haven't delved into the translation code yet). Also what is the experience using the following? http://quantlib.org http://www.qlnet.org (C# port of quantlib) or http://www.boost.org Any alternatives you know of? I'm a C# developer so would prefer C#, but a wrapper to C++ shouldn't be a problem, should it? Maybe even faster leveraging the C++ implementations. I am thinking some of these libraries will have the fastest method to directly generate normally distributed random numbers, without the translation step. Also they may have some other functions that will be helpful in the subsequent calculations. Also the computer this is on is a quad core Opteron 275, 8 GB memory but Windows Server 2003 Enterprise 32 bit. Should I advise them to upgrade to a 64 bit OS? Any links to articles supporting this decision would really be appreciated. Anyway, any advice and help you may have is really appreciated.

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• QueryInterface fails at casting inside COM-interface implementation

  - by brecht

  I am creating a tool in c# to retrieve messages of a CAN-network (network in a car) using an Dll written in C/C++. This dll is usable as a COM-interface. My c#-formclass implements one of these COM-interfaces. And other variables are instantiated using these COM-interfaces (everything works perfect). The problem: The interface my C#-form implements has 3 abstract functions. One of these functions is called -by the dll- and i need to implement it myself. In this function i wish to retrieve a property of a form-wide variable that is of a COM-type. The COM library is CANSUPPORTLib The form-wide variable: private CANSUPPORTLib.ICanIOEx devices = new CANSUPPORTLib.CanIO(); This variable is also form-wide and is retrieved via the devices-variable: canreceiver = (CANSUPPORTLib.IDirectCAN2)devices.get_DirectDispatch(receiverLogicalChannel); The function that is called by the dll and implemented in c# public void Message(double dTimeStamp) { Console.WriteLine("!!! message ontvangen !!!" + Environment.NewLine); try { CANSUPPORTLib.can_msg_tag message = new CANSUPPORTLib.can_msg_tag(); message = (CANSUPPORTLib.can_msg_tag) System.Runtime.InteropServices.Marshal.PtrToStructure(canreceiver.RawMessage, message.GetType()); for (int i = 0; i < message.data.Length; i++) { Console.WriteLine("byte " + i + ": " + message.data[i]); } } catch (Exception e) { Console.WriteLine(e.Message); } } The error rises at this line: message = (CANSUPPORTLib.can_msg_tag)System.Runtime.InteropServices.Marshal.PtrToStructure(canreceiver.RawMessage, message.GetType()); Error: Unable to cast COM object of type 'System.__ComObject' to interface type 'CANSUPPORTLib.IDirectCAN2'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{33373EFC-DB42-48C4-A719-3730B7F228B5}' failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)). Notes: It is possible to have a timer-clock that checks every 100ms for the message i need. The message is then retrieved in the exact same way as i do now. This timer is started when the form starts. The checking is only done when Message(double) has put a variable to true (a message arrived). When the timer-clock is started in the Message function, i have the same error as above Starting another thread when the form starts, is also not possible. Is there someone with experience with COM-interop ? When this timer

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• Importing a large dataset into a database

  - by peaceful

  I'm a beginning programmer in the relevant areas to this question, so if possible, it'd be helpful to avoid assuming I know a lot already. I'm trying to import the OpenLibrary dataset into a local Postgres database. After it's imported, I plan to use it as a starting seed for a Ruby on Rails application that will include information on books. The OpenLibrary datasets are available here, in a modified JSON format: http://openlibrary.org/dev/docs/jsondump I only need very basic information for my application, much less than what is provided in the dumps. I'm only trying to get out book titles, author names, and relationships between books and authors. Below are two typical entries from their dataset, the first for an author, and the second for a book (they seem to have an entry for each edition of a book). The entries seem to lead off with a primary key, and then with a type, before including the actual JSON database dump. /a/OL2A /type/author {"name": "U. Venkatakrishna Rao", "personal_name": "U. Venkatakrishna Rao", "last_modified": {"type": "/type/datetime", "value": "2008-09-10 08:44:01.978456"}, "key": "/a/OL2A", "birth_date": "1904", "type": {"key": "/type/author"}, "id": 99, "revision": 3} /b/OL345M /type/edition {"publishers": ["Social Science Research Project, Dept. of Geography, University of Dacca"], "pagination": "ii, 54 p.", "title": "Land use in Fayadabad area", "lccn": ["sa 65000491"], "subject_place": ["East Pakistan", "Dacca region."], "number_of_pages": 54, "languages": [{"comment": "initial import", "code": "eng", "name": "English", "key": "/l/eng"}], "lc_classifications": ["S471.P162 E23"], "publish_date": "1963", "publish_country": "pk ", "key": "/b/OL345M", "authors": [{"birth_date": "1911", "name": "Nafis Ahmad", "key": "/a/OL302A", "personal_name": "Nafis Ahmad"}], "publish_places": ["Dacca, East Pakistan"], "by_statement": "[by] Nafis Ahmad and F. Karim Khan.", "oclc_numbers": ["4671066"], "contributions": ["Khan, Fazle Karim, joint author."], "subjects": ["Land use -- East Pakistan -- Dacca region."]} The size of the uncompressed dumps are enormous, about 2GB for the authors list, and 18GB for the book editions list. OpenLibrary does not provide any tools for this themselves, they provide a simple unoptimized Python script for reading in sample data (which unlike the actual dumps comes in pure JSON format), but they estimate if that was modified for use on their actual data it would take 2 months (!) to finish loading the data. How can I read this into the database? I assume I'll need to write a program to do this. What language and any guidance on how I should do it to finish in a reasonable amount of time? The only scripting language I have any experience with is Ruby.

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• jBASE 4.1 Database Noobster Questions

  - by Steve Johnson

  I am a software developer with devlopment experience in C#, C++ .Net alongwith SQL Server 2005/08, Oracle and mysql. But somehow i dont get jBASE to work at Windows XP SP3 machine. My goal is setup user accounts, create database on a JBASE ainstallation, authenticate and backup/restore few table via a C++ program. And i dont need to do it with builtin backup/restore tools of jBASE. I am able to install jBASe 4.1 aling with all its accessories on my WINXPSP3 machine. I was able to run the jSlimserver and TEMENOUS server along with licnesing server. I was able to add the license key as well. But after that what i was supposed to do? i have no idea about it. The docs and online help doesnt answer a simple question of how to create a database! The google search results from the jbase site all go to the 404 Pages! Can a jBASE expert guide to the following steps: Create a jBASE database. Create users Authenticate via those users Connect to database Create tables and insert data. Connect via a C++ or C# program to connect to jBASE DB and backup/restore tables. I know that this is too much too ask but i dont get to get the JBASE system. I cant get it to work on my System somehow. Btw, jdc and jexloree doesnt seem to do anything. I have checked that enironmental variables for jBASE are setup correctly and i have verified them. There are no extra JRE or JDK installations on my system. Besides all that, only licensing client, slim server and temenous server seem to run and listen for connections and no other execuatable ever seems to work. A simple tutorial to achieve the objective will be highly appreciated. Also if anyone can point out the mistake that i have done or anything i might need to check, then please do so. I will be highly encouraged and obliged. Thanks Steve

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• Neural Networks in C# using NeuronDotNet

  - by kingrichard2005

  Hello, I'm testing the NeuronDotNet library for a class assignment using C#. I have a very simple console application that I'm using to test some of the code snippets provided in the manual fro the library, the goal of the assignment is to teach the program how to distinguish between random points in a square which may or may not be within a circle that is also inside the square. So basically, which points inside the square are also inside the circle. Here is what I have so far: namespace _469_A7 { class Program { static void Main(string[] args) { //Initlaize the backpropogation network LinearLayer inputLayer = new LinearLayer(2); SigmoidLayer hiddenLayer = new SigmoidLayer(8); SigmoidLayer outputLayer = new SigmoidLayer(2); new BackpropagationConnector(inputLayer, hiddenLayer); new BackpropagationConnector(hiddenLayer, outputLayer); BackpropagationNetwork network = new BackpropagationNetwork(inputLayer, outputLayer); //Generate a training set for the ANN TrainingSet trainingSet = new TrainingSet(2, 2); //TEST: Generate random set of points and add to training set, //for testing purposes start with 10 samples; Point p; Program program = new Program(); //Used to access randdouble function Random rand = new Random(); for(int i = 0; i < 10; i++) { //These points will be within the circle radius Type A if(rand.NextDouble() > 0.5) { p = new Point(rand.NextDouble(), rand.NextDouble()); trainingSet.Add(new TrainingSample(new double[2] { p.getX(), p.getY() }, new double[2] { 1, 0 })); continue; } //These points will either be on the border or outside the circle Type B p = new Point(program.randdouble(1.0, 4.0), program.randdouble(1.0, 4.0)); trainingSet.Add(new TrainingSample(new double[2] { p.getX(), p.getY() }, new double[2] { 0, 1 })); } //Start network learning network.Learn(trainingSet, 100); //Stop network learning //network.StopLearning(); } //generates a psuedo-random double between min and max public double randdouble(double min, double max) { Random rand = new Random(); if (min > max) { return rand.NextDouble() * (min - max) + max; } else { return rand.NextDouble() * (max - min) + min; } } } //Class defines a point in X/Y coordinates public class Point { private double X; private double Y; public Point(double xVal, double yVal) { this.X = xVal; this.Y = yVal; } public double getX() { return X; } public double getY() { return Y; } } } This is basically all that I need, the only question I have is how to handle output?? More specifically, I need to output the value of the "step size" and the momentum, although it would be nice to output other information as well. Anyone with experience using NeuronDotNet, your input is appreciated.

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• Using Objective-C Blocks

  - by Sean

  Today I was experimenting with Objective-C's blocks so I thought I'd be clever and add to NSArray a few functional-style collection methods that I've seen in other languages: @interface NSArray (FunWithBlocks) - (NSArray *)collect:(id (^)(id obj))block; - (NSArray *)select:(BOOL (^)(id obj))block; - (NSArray *)flattenedArray; @end The collect: method takes a block which is called for each item in the array and expected to return the results of some operation using that item. The result is the collection of all of those results. (If the block returns nil, nothing is added to the result set.) The select: method will return a new array with only the items from the original that, when passed as an argument to the block, the block returned YES. And finally, the flattenedArray method iterates over the array's items. If an item is an array, it recursively calls flattenedArray on it and adds the results to the result set. If the item isn't an array, it adds the item to the result set. The result set is returned when everything is finished. So now that I had some infrastructure, I needed a test case. I decided to find all package files in the system's application directories. This is what I came up with: NSArray *packagePaths = [[[NSSearchPathForDirectoriesInDomains(NSAllApplicationsDirectory, NSAllDomainsMask, YES) collect:^(id path) { return (id)[[[NSFileManager defaultManager] contentsOfDirectoryAtPath:path error:nil] collect:^(id file) { return (id)[path stringByAppendingPathComponent:file]; }]; }] flattenedArray] select:^(id fullPath) { return [[NSWorkspace sharedWorkspace] isFilePackageAtPath:fullPath]; }]; Yep - that's all one line and it's horrid. I tried a few approaches at adding newlines and indentation to try to clean it up, but it still feels like the actual algorithm is lost in all the noise. I don't know if it's just a syntax thing or my relative in-experience with using a functional style that's the problem, though. For comparison, I decided to do it "the old fashioned way" and just use loops: NSMutableArray *packagePaths = [NSMutableArray new]; for (NSString *searchPath in NSSearchPathForDirectoriesInDomains(NSAllApplicationsDirectory, NSAllDomainsMask, YES)) { for (NSString *file in [[NSFileManager defaultManager] contentsOfDirectoryAtPath:searchPath error:nil]) { NSString *packagePath = [searchPath stringByAppendingPathComponent:file]; if ([[NSWorkspace sharedWorkspace] isFilePackageAtPath:packagePath]) { [packagePaths addObject:packagePath]; } } } IMO this version was easier to write and is more readable to boot. I suppose it's possible this was somehow a bad example, but it seems like a legitimate way to use blocks to me. (Am I wrong?) Am I missing something about how to write or structure Objective-C code with blocks that would clean this up and make it clearer than (or even just as clear as) the looped version?

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• NSObjectController confusion binding to a class property. Help!

  - by scottw

  Hi, I'm teaching myself cocoa and enjoying the experience most of the time. I have been struggling all day with a simple problem that google has let me down on. I have read the Cocoa Bindings Program Topics and think I grok it but still can't solve my issue. I have a very simple class called MTSong that has various properties. I have used @synthesize to create getter/setters and can use KVC to change properties. i.e in my app controller the following works: mySong = [[MTSong alloc]init]; [mySong setValue:@"2" forKey:@"version"]; In case I am doing something noddy in my class code MTSong.h is: #import <Foundation/Foundation.h> @interface MTSong : NSObject { NSNumber *version; NSString *name; } @property(readwrite, assign) NSNumber *version; @property(readwrite, assign) NSString *name; @end and MTSong.m is: #import "MTSong.h" @implementation MTSong - (id)init { [super init]; return self; } - (void)dealloc { [super dealloc]; } @synthesize version; @synthesize name; @end In Interface Builder I have a label (NSTextField) that I want to update whenever I use KVC to change the version of the song. I do the following: Drag NSObjectController object into the doc window and in the Inspector-Attributes I set: Mode: Class Class Name: MTSong Add a key called version and another called name Go to Inspector-Bindings-Controller Content Bind To: File's Owner (Not sure this is right...) Model Key Path: version Select the cell of the label and go to Inspector Bind to: Object Controller Controller Key: mySong Model Key Path: version I have attempted changing the Model Key Path in step 2 to "mySong" which makes more sense but the compiler complains. Any suggestions would be greatly appreciated. Scott Update Post Comments I wasn't exposing mySong property so have changed my AppController.h to be: #import <Cocoa/Cocoa.h> @class MTSong; @interface AppController : NSObject { IBOutlet NSButton *start; IBOutlet NSTextField *tf; MTSong *mySong; } -(IBAction)convertFile:(id)sender; @end I suspect File's owner was wrong as I am not using a document based application and I need to bind to the AppController, so step 2 is now: Go to Inspector-Bindings-Controller Content Bind To: App Controller Model Key Path: mySong I needed to change 3. to Select the cell of the label and go to Inspector Bind to: Object Controller Controller Key: selection Model Key Path: version All compiles and is playing nice!

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• How to best design a date/geographic proximity query on GAE?

  - by Dane

  Hi all, I'm building a directory for finding athletic tournaments on GAE with web2py and a Flex front end. The user selects a location, a radius, and a maximum date from a set of choices. I have a basic version of this query implemented, but it's inefficient and slow. One way I know I can improve it is by condensing the many individual queries I'm using to assemble the objects into bulk queries. I just learned that was possible. But I'm also thinking about a more extensive redesign that utilizes memcache. The main problem is that I can't query the datastore by location because GAE won't allow multiple numerical comparison statements (<,<=,=,) in one query. I'm already using one for date, and I'd need TWO to check both latitude and longitude, so it's a no go. Currently, my algorithm looks like this: 1.) Query by date and select 2.) Use destination function from geopy's distance module to find the max and min latitude and longitudes for supplied distance 3.) Loop through results and remove all with lat/lng outside max/min 4.) Loop through again and use distance function to check exact distance, because step 2 will include some areas outside the radius. Remove results outside supplied distance (is this 2/3/4 combination inefficent?) 5.) Assemble many-to-many lists and attach to objects (this is where I need to switch to bulk operations) 6.) Return to client Here's my plan for using memcache.. let me know if I'm way out in left field on this as I have no prior experience with memcache or server caching in general. -Keep a list in the cache filled with "geo objects" that represent all my data. These have five properties: latitude, longitude, event_id, event_type (in anticipation of expanding beyond tournaments), and start_date. This list will be sorted by date. -Also keep a dict of pointers in the cache which represent the start and end indices in the cache for all the date ranges my app uses (next week, 2 weeks, month, 3 months, 6 months, year, 2 years). -Have a scheduled task that updates the pointers daily at 12am. -Add new inserts to the cache as well as the datastore; update pointers. Using this design, the algorithm would now look like: 1.) Use pointers to slice off appropriate chunk of list based on supplied date. 2-4.) Same as above algorithm, except with geo objects 5.) Use bulk operation to select full tournaments using remaining geo objects' event_ids 6.) Assemble many-to-manys 7.) Return to client Thoughts on this approach? Many thanks for reading and any advice you can give. -Dane

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• Java language features which have no equivalent in C#

  - by jthg

  Having mostly worked with C#, I tend to think in terms of C# features which aren't available in Java. After working extensively with Java over the last year, I've started to discover Java features that I wish were in C#. Below is a list of the ones that I'm aware of. Can anyone think of other Java language features which a person with a C# background may not realize exists? The articles http://www.25hoursaday.com/CsharpVsJava.html and http://en.wikipedia.org/wiki/Comparison_of_Java_and_C_Sharp give a very extensive list of differences between Java and C#, but I wonder whether I missed anything in the (very) long articles. I can also think of one feature (covariant return type) which I didn't see mentioned in either article. Please limit answers to language or core library features which can't be effectively implemented by your own custom code or third party libraries. Covariant return type - a method can be overridden by a method which returns a more specific type. Useful when implementing an interface or extending a class and you want a method to override a base method, but return a type more specific to your class. Enums are classes - an enum is a full class in java, rather than a wrapper around a primitive like in .Net. Java allows you to define fields and methods on an enum. Anonymous inner classes - define an anonymous class which implements a method. Although most of the use cases for this in Java are covered by delegates in .Net, there are some cases in which you really need to pass multiple callbacks as a group. It would be nice to have the choice of using an anonymous inner class. Checked exceptions - I can see how this is useful in the context of common designs used with Java applications, but my experience with .Net has put me in a habit of using exceptions only for unrecoverable conditions. I.E. exceptions indicate a bug in the application and are only caught for the purpose of logging. I haven't quite come around to the idea of using exceptions for normal program flow. strictfp - Ensures strict floating point arithmetic. I'm not sure what kind of applications would find this useful. fields in interfaces - It's possible to declare fields in interfaces. I've never used this. static imports - Allows one to use the static methods of a class without qualifying it with the class name. I just realized today that this feature exists. It sounds like a nice convenience.

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• html widget communicating with server

  - by Nikita Rybak

  I'm making html widget for websites. Let's say, it will display current stock indexes. In short, arbitrary website owner takes code snippet from me and includes it on his webpage http://website.com/index.html. When arbitrary user opens http://website.com/index.html, my code sends request to my server (provider.com), which performs necessary operations and returns information to user's browser. When response has arrived, user will see relevant stock value on http://website.com/index.html. In index.html service could be called like this <script type="text/javascript" src="provider.com/service.js"> </script> <div id="target_area"></div> <script type="text/javascript"> service.show("target_area", options); </script> Now, the problem is in the same origin policy: I can't just send ajax request from website.com to provided.com and return html to embed in client's webpage. I see several solutions, which I list below, but none quite satisfy me. I wonder, if you could suggest something, especially if you had some relevant experience. 1) iframe, plain and simple. Disadvantage: must have fixed dimensions + stupid scroll bars appearing in some browsers. Can be fixed with javascript, but all this browser-specific tinkering doesn't sound good to me. 2) JSONP. Problem: can't return whole chunk of html, must return only data. Then, on browser side, I'll have to use javascript to embed data into html snippet placed statically in index.html. Doesn't sound nice, because data format is not very simple and may even change later. 3) Use hidden iframe to do ajax requests. A bit tricky, but sounds like a way to go. Well, that's my thoughts on the subject. Are there any better ways? BTW, I tried to check some existing widgets too, but didn't find much useful information. All domain names used in this text are fictional and any resemblance is purely coincidental :)

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• [JavaScript-CSS-Firefox] Cannot change borderColor of TD

  - by Tadeus Prastowo

  Using JS to set the background color of a TD is fine. But, setting the border color is problematic in FF 3.0.18 although IE 6 doesn't experience this. FF is problematic in that it requires the TD element to have an attribute style initialized to border-style: solid. Without that, setting border color of a TD won't work. Is this known bug? How do I set the border color without having to set style attribute as well as the initialization value? I know another trick of setting the class attribute instead of setting the border color directly. Is this an indication that somehow TD hates having its border color set dynamically? Is this known as well? The problematic code is below (the goal is find out why setting the border color of simple truth 1 does not work while simple truth 3 works when I employ the trick described above): <html> <head> <title>Quirks FF 3.0.18</title> <style type="text/css"> table { border-collapse: collapse; } </style> <script type="text/javascript"> function changeBgColor() { document.getElementById('simple').style.backgroundColor='yellow'; document.getElementById('simple2').style.backgroundColor='yellow'; document.getElementById('simple3').style.backgroundColor='yellow'; } function quirk(id) { var x = document.getElementById(id); x.style.border = '2px solid red'; } </script> </head> <body> <input type="button" onclick="changeBgColor()" value="Change background color"/> <input type="button" onclick="quirk('simple')" value="Change border color 1"/> <input type="button" onclick="quirk('simple2')" value="Change border color 2"/> <input type="button" onclick="quirk('simple3')" value="Change border color 3"/> <table> <tr><td id="simple">Simple truth 1</td></tr> </table> <table> <tr><td><span id="simple2">Simple truth 2</span></td></tr> <table> <tr><td id="simple3" style="border-style: solid">Simple truth 3</td></tr> </table> </body> </html>

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• Animating custom-drawn UITableViewCell when entering edit mode

  - by Adam Alexander

  Background First of all, much gratitude to atebits for their very informative blog post Fast Scrolling in Tweetie with UITableView. The post explains in detail how the developers were able to squeeze as much scrolling performance as possible out of the UITableViews in Tweetie. Goals Beginning with the source code linked from the blog post (original) (my github repo): Allow a UITableView using these custom cells to switch to edit mode, exposing the UI for deleting an item from the table. (github commit) Move the cell's text aside as the deletion control slides in from the left. This is complete, although the text jumps back and forth without animation. (github commit) Apply animation to the text movement in goal 2 above for a smooth user experience. This is the step where I became stuck. The Question What is the best way to introduce this animation to complete goal 3? It would be nice if this could be done in a manner that keeps the logic from my last commit because I would love the option to move the conflicting part of the view only, while any non-conflicting portions (such as right-justified text) stay in the same place or move a different number of pixels. If the above is not possible then undoing my last commit and replacing it with an option that slides the entire view to the right would be a workable solution also. I appreciate any help anyone can provide, from quick pointers and ideas all the way to code snippets or github commits. Of course you are welcome to fork my repo if you would like. I will be staying involved with this question to make sure any successful resolution is committed to github and fully documented here. Thanks very much for your time! Updated thoughts I have been thinking about this a lot since my first post and realized that moving some text items relative to others in the view could undo some of the original performance goals solved in the original blog post. So at this point I am thinking a solution where the entire single subview is animated to its new postion may be the best one. Second, if it is done in this way there may be an instance where the subview has a custom color or gradient background. Hopefully this can be done in a way that in its normal position the background extends unseen off to the left enough so that when the view is slid to the right the custom background is still visible across the entire cell.

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• Best practices concerning view model and model updates with a subset of the fields

  - by Martin

  By picking MVC for developing our new site, I find myself in the midst of "best practices" being developed around me in apparent real time. Two weeks ago, NerdDinner was my guide but with the development of MVC 2, even it seems outdated. It's an thrilling experience and I feel privileged to be in close contact with intelligent programmers daily. Right now I've stumbled upon an issue I can't seem to get a straight answer on - from all the blogs anyway - and I'd like to get some insight from the community. It's about Editing (read: Edit action). The bulk of material out there, tutorials and blogs, deal with creating and view the model. So while this question may not spell out a question, I hope to get some discussion going, contributing to my decision about the path of development I'm to take. My model represents a user with several fields like name, address and email. All the names, in fact, on field each for first name, last name and middle name. The Details view displays all these fields but you can change only one set of fields at a time, for instance, your names. The user expands a form while the other fields are still visible above and below. So the form that is posted back contains a subset of the fields representing the model. While this is appealing to us and our layout concerns, for various reasons, it is to be shunned by serious MVC-developers. I've been reading about some patterns and best practices and it seems that this is not in key with the paradigm of viewmodel == view. Or have I got it wrong? Anyway, NerdDinner dictates using FormCollection och UpdateModel. All the null fields are happily ignored. Since then, the MVC-community has abandoned this approach to such a degree that a bug in MVC 2 was not discovered. UpdateModel does not work without a complete model in your formcollection. The view model pattern receiving most praise seems to be Dedicated view model that contains a custom view model entity and is the only one that my design issue could be made compatible with. It entails a tedious amount of mapping, albeit lightened by the use of AutoMapper and the ideas of Jimmy Bogard, that may or may not be worthwhile. He also proposes a 1:1 relationship between view and view model. In keeping with these design paradigms, I am to create a view and associated view for each of my expanding sets of fields. The view models would each be nearly identical, differing only in the fields which are read-only, the views also containing much repeated markup. This seems absurd to me. In future I may want to be able to display two, more or all sets of fields open simultaneously. I will most attentively read the discussion I hope to spark. Many thanks in advance.

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• Using Linq to filter a ComboBox.DataSource ?

  - by Pesche Helfer

  Hi board, in another topic, I've stumbled over this very elegant solution by Darin Dimitrov to filter the DataSource of one ComboBox with the selection of another ComboBox: how to filter combobox in combobox using c# combo2.DataSource = ((IEnumerable<string>)c.DataSource) .Where(x => x == (string)combo1.SelectedValue); I would like to do a similar thing, but intead of filtering by a second combobox, I would like to filter by the text of a TextBox. (Basically, instead of choosing from a second ComboBox, the user simply enters his filter in to a TextBox). However, it turned out to be not as straight forward as I had hoped it would be. I tried stuff as the following, but failed miserably: cbWohndresse.DataSource = ((IEnumerable<DataSet>)ds) .Where(x => x.Tables["Adresse"].Select("AdrLabel LIKE '%TEST%'")); cbWohndresse.DisplayMember = "Adresse.AdrLabel"; cbWohndresse.ValueMember = "Adresse.adress_id"; ds is the DataSet which I would like to use as filtered DataSource. "Adresse" is one DataTable in this DataSet. It contains a DataColumn "AdrLabel". Now I would like to display only those "AdrLabel", which contain the string from the user input. (Currently, %TEST% replaces the textbox.text.) The above code fails because the lambda expression does not return Bool. But I am sure, there are also other problems (which type should I use for IEnumerable? Now it's DataSet, but Darin used String. But how could I convert a DataSet to a string? Yes, I am as much newbyish as it gets, my experience is "void", and publicly so. So please forgive me my rather stupid questions. Your help is greatly appreciated, because I can't solve this on my own (tried hard already). Thank you very much! Pesche P.S. I am only using Linq to achieve an uncomplicated filter for the ComboBox (avoiding a View). The rest is not based on Linq, but on oldstyle Ado.NET (ds is filled by an SqlDataAdapter), if that's of any importance.

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• Using XMLDecoder to cast Encoded XML to List<>

  - by Ender

  I am writing an application that reads in a large number of basic user details in the following format; once read in it then allows the user to search for a user's details using their email: NAME ROLE EMAIL --------------------------------------------------- Joe Bloggs Manager [email protected] John Smith Consultant [email protected] Alan Wright Tester [email protected] ... The problem I am suffering is that I need to store a large number of details of all people that have worked at the company. The file containing these details will be written on a yearly basis simply for reporting purposes, but the program will need to be able to access these details quickly. The way I aim to access these files is to have a program that asks the user for the name of the unique email of the member of staff and for the program to then return the name and the role from that line of the file. I've played around with text files, but am struggling with how I would handle multiple columns of data when it comes to searching this large file. What is the best format to store such data in? A text file? XML? The size doesn't bother me, but I'd like to be able to search it as quickly as possible. The file will need to contain a lot of entries, probably over the 10K mark over time. EDIT: I've decided to go with the XML serialisation method. I've managed to get the code for Encoding working perfectly, but the Decoding code below does not work. XMLDecoder d = new XMLDecoder( new BufferedInputStream(new FileInputStream("data.xml"))); List<Employee> list = (List<Employee>) d.readObject(); d.close(); for(Employee x : list) { if(x.getEmail().equals(userInput)) { // do stuff } } When the program hits List<Employee> list = (List<Employee>) d.readObject(); an exception is thrown claiming that "Employee cannot be cast to java.util.List". I've added a bounty to this and anyone that can help me solve this problem once and for all will get lots of lovely points. EDIT 2: I've looked a bit more into the problem and have come across Serialization as a potential answer. If anyone can look into this for me as I've no experience with Serialization or Deserialization I'd be very grateful. It can provide an Object with no problems whatsoever, but I really need to return it in the same format as it went in (List). EDIT 3: Ugh, this problem is really starting to drive me crazy and to be honest I'm starting to think that it's an unsolvable problem. If possible, could someone take a look at the code and help provide a solution for me?

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