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• Is the science of Computer Science dead?

  - by Veaviticus

  Question : Is the science and art of CS dead? By that I mean, the real requirements to think, plan and efficiently solve problems seems to be falling away from CS these days. The field seems to be lowering the entry-barrier so more people can 'program' without having to learn how to truly program. Background : I'm a recent graduate with a BS in Computer Science. I'm working a starting position at a decent sized company in the IT department. I mostly do .NET and other Microsoft technologies at my job, but before this I've done Java stuff through internships and the like. I personally am a C++ programmer for my own for-fun projects. In Depth : Through the work I've been doing, it seems to me that the intense disciplines of a real science don't exist in CS anymore. In the past, programmers had to solve problems efficiently in order for systems to be robust and quick. But now, with the prevailing technologies like .NET, Java and scripting languages, it seems like efficiency and robustness have been traded for ease of development. Most of the colleagues that I work with don't even have degrees in Computer Science. Most graduated with Electrical Engineering degrees, a few with Software Engineering, even some who came from tech schools without a 4 year program. Yet they get by just fine without having the technical background of CS, without having studied theories and algorithms, without having any regard for making an elegant solution (they just go for the easiest, cheapest solution). The company pushes us to use Microsoft technologies, which take all the real thought out of the matter and replace it with libraries and tools that can auto-build your project for you half the time. I'm not trying to hate on the languages, I understand that they serve a purpose and do it well, but when your employees don't know how a hash-table works, and use the wrong sorting methods, or run SQL commands that are horribly inefficient (but get the job done in an acceptable time), it feels like more effort is being put into developing technologies that coddle new 'programmers' rather than actually teaching people how to do things right. I am interested in making efficient and, in my opinion, beautiful programs. If there is a better way to do it, I'd rather go back and refactor it than let it slide. But in the corporate world, they push me to complete tasks quickly rather than elegantly. And that really bugs me. Is this what I'm going to be looking forward to the rest of my life? Are there still positions out there for people who love the science and art of CS rather than just the paycheck? And on the same note, here's a good read if you haven't seen it before The Perils Of Java Schools

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• What are the options for hosting a small Plone site? [closed]

  - by Tina Russell

  Possible Duplicate: How to find web hosting that meets my requirements? I’ve developed a portfolio website for myself using Plone 4, and I’m looking for someplace to host it. Most Plone hosting services seem to focus on large, corporate deployments, but I need something that I can afford on a very limited budget and fits a small, single-admin website. My understanding is that my basic options are thus: I can go with a hosting service that specifically provides Plone. I know of WebFaction, but what others exist? Also, I’d have two stipulations for a Plone hosting service: (a) It needs to use Plone 4, for which I’ve developed my site, and (b) it needs to allow me SSH access to a home directory (including the Plone configuration), so that I may use my custom development eggs and such. I could use a VPS hosting service. What are my options here? Again, I need something cheap and scaled to my level. I could use Amazon EC2 or a similar service (please tell me of any) and pay by the tiniest unit of data. I’m a little scared of this because I have no idea how to do a cost-benefit analysis between this and a regular VPS host. The advantage of this approach would be that I only pay for what I use, making it very scalable, but I don’t know how the overall cost would compare to any VPS host under similar circumstances. What factors enter into the cost of Amazon EC2? What can I expect to pay under either option for regular traffic for a new website? Which one is more desirable for when a rush of visitors drive up my bandwidth bill? One last note: I know Plone isn’t common for websites for individuals, but please don’t try to talk me out of it here; that’s a completely different subject. For now, assume I’m sticking with Plone for good. Also, I have seen the Plone hosting services list on Plone.org—it’s twenty pages long, and the first page was nothing but professional Plone consulting services that sometimes offer hosting for business clients. So, that wasn’t much help. Thank you!

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• Where to draw the line between development-led security and administration-led security?

  - by haylem

  There are cases where you have the opportunity, as a developer, to enforce stricter security features and protections on a software, though they could very well be managed at an environmental level (ie, the operating system would take care of it). Where would you say you draw the line, and what elements do you factor in your decision? Concrete Examples User Management is the OS's responsibility Not exactly meant as a security feature, but in a similar case Google Chrome used to not allow separate profiles. The invoked reason (though it now supports multiple profiles for a same OS user) used to be that user management was the operating system's responsibility. Disabling Web-Form Fields A recurrent request I see addressed online is to have auto-completion be disabled on form fields. Auto-completion didn't exist in old browsers, and was a welcome feature at the time it was introduced for people who needed to fill in forms often. But it also brought in some security concerns, and so some browsers started to implement, on top of the (obviously needed) setting in their own preference/customization panel, an autocomplete attribute for form or input fields. And this has now been introduced into the upcoming HTML5 standard. For browsers who do not listen to this attribute, strange hacks *\ are offered, like generating unique IDs and names for fields to avoid them from being suggested in future forms (which comes with another herd of issues, like polluting your local auto-fill cache and not preventing a password from being stored in it, but instead probably duplicating its occurences). In this particular case, and others, I'd argue that this is a user setting and that it's the user's desire and the user's responsibility to enable or disable auto-fill (by disabling the feature altogether). And if it is based on an internal policy and security requirement in a corporate environment, then substitute the user for the administrator in the above. I assume it could be counter-argued that the user may want to access non-critical applications (or sites) with this handy feature enabled, and critical applications with this feature disabled. But then I'd think that's what security zones are for (in some browsers), or the sign that you need a more secure (and dedicated) environment / account to use these applications. * I obviously don't deny the ingenuity of the people who were forced to find workarounds, just the necessity of said workarounds. Questions That was a tad long-winded, so I guess my questions are: Would you in general consider it to be the application's (hence, the developer's) responsiblity? Where do you draw the line, if not in the "general" case?

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• Going Inside the Store

  - by David Dorf

  Location was the first "killer-tech" for smartphones, and innovators have found several ways to use it. For retail, apps exist to find nearby stores, provide coupons, and give directions to the front door. But once you enter the store, location-finding ceases to work. That's because your location is usually found by finding GPS satellites in they sky, and the store's roof blocks the signal. But it won't take technology long to solve that problem. The first problem to solve is a lack of indoor maps. Navteq and others provide very accurate maps of the outdoors, enabling navigation for cars and pedestrians. Micello is building a business creating digital maps of indoor locations like malls, convention centers, office buildings. They have over 500 live maps, including maps of IKEA stores. They claim it took them only four hours to create a map of the Stanford Shopping Center in Palo Alto with its 1.4 million square feet and 140 retail stores. And within stores, retailers are producing more accurate plan-o-grams. I'm always impressed watching demos of our space planning from AVT. It uses CAD software to allow you to walk the virtual store and see products on the shelves. The second problem is being able to determine location inside the store so it can be overlayed on the map. There are several goals for this endeavor. Your smartphone might direct you straight to particular products, it might summon a sales associate to your location for immediate assistance, and it might send you coupons based on the aisle you're viewing. Companies like Nearbuy, ZuluTime, and Skyhook are working to master indoor location using a combination of GPS signals, WiFi, and cell tower positioning to calculate a location. (Skyhook calls this WPS, as depicted in the chart.) Today they can usually hit 10 meters accuracy, but that number is improving all the time. When it gets inside 3 meters some the goals mentioned earlier will be in easy reach. I for one can't wait until the time my iPhone leads me directly to the sprinkler heads in Lowes and Home Depot.

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• PHP MVC error handling, view display and user permissions

  - by cen

  I am building a moderation panel from scratch in a MVC approach and a lot of questions cropped up during development. I would like to hear from others how they handle these situations. Error handling Should you handle an error inside the class method or should the method return something anyway and you handle the error in controller? What about PDO exceptions, how to handle them? For example, let's say we have a method that returns true if the user exists in a table and false if he does not exist. What do you return in the catch statement? You can't just return false because then the controller assumes that everything is alright while the truth is that something must be seriously broken. Displaying the error from the method completely breaks the whole design. Maybe a page redirect inside the method? The proper way to show a view The controller right now looks something like this: include('view/header.php'); if ($_GET['m']=='something') include('view/something.php'); elseif ($_GET['m']=='somethingelse') include('view/somethingelse.php'); include('view/foter.php'); Each view also checks if it was included from the index page to prevent it being accessed directly. There is a view file for each different document body. Is this way of including different views ok or is there a more proper way? Managing user rights Each user has his own rights, what he can see and what he can do. Which part of the system should verify that user has the permission to see the view, controller or view itself? Right now I do permission checks directly in the view because each view can contain several forms that require different permissions and I would need to make a seperate file for each of them if it was put in the controller. I also have to re-check for the permissions everytime a form is submitted because form data can be easily forged. The truth is, all this permission checking and validating the inputs just turns the controller into a huge if/then/else cluster. I feel like 90% of the time I am doing error checks/permissions/validations and very little of the actual logic. Is this normal even for popular frameworks?

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• SQL SERVER – Creating All New Database with Full Recovery Model

  - by pinaldave

  Sometimes, complex problems have very simple solutions. Let us see the following email which I received recently. “Hi Pinal, In our system when we create new database, by default, they are all created with the Simple Recovery Model. We have to manually change the recovery model after we create the database. We used the following simple T-SQL code: CREATE DATABASE dbname. We are very frustrated with this situation. We want all our databases to have the Full Recovery Model option by default. We are considering the following methods; please suggest the most efficient one among them. 1) Creating a Policy; when it is violated, the database model can be fixed 2) Triggers at Server Level 3) Automated Job which goes through all the databases and checks their recovery model; if the DBA has not changed the model, then the job will list the Databases and change their recovery model Also, we have a situation where we need a database in the Simple Recovery Model as well – how to white list them? Please suggest the best method.” Indeed, an interesting email! The answer to their question, i.e., which is the best method to fit their needs (white list, default, etc)? It will be NONE of the above. Here is the solution in one line and also the easiest way: Just go to your Model database: Path in SSMS >> Databases > System Databases >> model >> Right Click Properties >> Options >> Recovery Model - Select Full from dropdown. Every newly created database takes its base template from the Model Database. If you create a custom SP in the Model Database, when you create a new database, it will automatically exist in that database. Any database that was already created before making changes in the Model Database will not be affected at all. Creating Policy is also a good method, and I will blog about this in a separate blog post, but looking at current specifications of the reader, I think the Model Database should be modified to have a Full Recovery Option. While writing this blog post, I remembered my another blog post where the model database log file was growing drastically even though there were no transactions SQL SERVER – Log File Growing for Model Database – model Database Log File Grew Too Big. NOTE: Please do not touch the Model Database unnecessary. It is a strict “No.” If you want to create an object that you need in all the databases, then instead of creating it in model database, I suggest that you create a new database called maintenance and create the object there. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, Readers Question, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Back-sliding into Unmanaged Code

  - by Laila

  It is difficult to write about Microsoft's ambivalence to .NET without mentioning clichés about dog food.  In case you've been away a long time, you'll remember that Microsoft surprised everyone with the speed and energy with which it introduced and evangelised the .NET Framework for managed code. There was good reason for this. Once it became obvious to all that it had sleepwalked into third place as a provider of development languages, behind Borland and Sun, it reacted quickly to attract the best talent in the industry to produce a windows version of the Java runtime, with Bounds-checking, Automatic Garbage collection, structures exception handling and common data types. To develop applications for this managed runtime, it produced several excellent languages, and more are being provided. The only thing Microsoft ever got wrong was to give it a stupid name. The logical step for Microsoft would be to base the entire operating system on the .NET framework, and to re-engineer its own applications. In 2002, Bill Gates, then Microsoft Chairman and Chief Software Architect said about their plans for .NET, "This is a long-term approach. These things don't happen overnight." Now, eight years later, we're still waiting for signs of the 'long-term approach'. Microsoft's vision of an entirely managed operating system has subsided since the Vista fiasco, but stays alive yet dormant as Midori, still being developed by Microsoft Research. This is an Internet-centric fork of the singularity operating system, a research project started in 2003 to build a highly-dependable operating system in which the kernel, device drivers, and applications are all written in managed code. Midori is predicated on the prevalence of connected systems, with provisions for distributed concurrency where application components exist 'in the cloud', and supports a programming model that can tolerate cancellation, intermittent connectivity and latency. It features an entirely new security model that sandboxes applications for increased security. So have Microsoft converted its existing applications to the .NET framework? It seems not. What Windows applications can run on Mono? Very few, it seems. We all thought that .NET spelt the end of DLL Hell and the need for COM interop, but it looks as if Bill Gates' idea of 'not overnight' might stretch to a decade or more. The Operating System has shown only minimal signs of migrating to .NET. Even where the use of .NET has come to dominate, when used for server applications with IIS, IIS itself is still entirely developed in unmanaged code. This is an irritation to Microsoft's greatest supporters who committed themselves fully to the NET framework, only to find parts of the Ambivalent Microsoft Empire quietly backsliding into unmanaged code and the awful C++. It is a strategic mistake that the invigorated Apple didn't make with the Mac OS X Architecture. Cheers, Laila

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• K2 4.5 Quick Thoughts

  I just finished attending a webcast on K2 4.5 and I thought Id share a few quick thoughts. Power User Story Improved Given it is just a presentation and I havent actually played with it, the story seemed improved and more believable that real world power users would be able to define workflows in SharePoint.  Power users who would be comfortable with Excel functions may be able to do some more worthwhile workflows since there is new support for inline functions and conditions.  The new SilverLight K2 designer seems pretty user friendly, though the dialog windows can really stack up which may get confusing.  I thought the neatest part was that the workflow can be defined just by starting with a SharePoint Lists settings which may be okay for some organizations and simpler workflows that dont need to define the workflow and push it through lots of testing in different environments.  The standalone K2 Studio is back.  In K2 2003 it was required because Visual Studio integration didnt exist.  Its back now for use by power users who need functionality up to the point of code.  Not sure if this Administration/Installation Installation is supposed to be simplified, with unattended install and other details I didnt catch.  Install and configuration has always seemed daunting to me so anything to improve that is good.  Related to that there is a new tool that is meant to help diagnose issues in your installation.  That may include figuring out missing permissions or services that arent running.  Also, now all K2 SharePoint features deployed as solutions. Dynamic SQL Service Broker Create a smart object to go against a table that you created, NOT the SmartBox.  This seems promising and something that maybe should have been there all along. Reference Event Allows you to call functionally that youve referenced, in the sample showing it was calling a web service that was referenced.  It seemed odd because it was really like writing code using dialogs (call constructor, set timeout, call web service method).  Seemed a little odd to me. Help We were reminded that help.k2.com site is newish site that is supposed to be the MSDN of K2 for partners and customers. VS 2010 Support Still no hard date on this, but what we were told is approximately 90 days after VS 2010 is officially released.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Running Teamsite User Admin tool IWUSERADM.exe from ASP.NET

  - by Narendra Tiwari

  It has really been a head scratching task for me. I 've tried many options but nothing worked. Finally I found a workaround on google to achive this by TaskScheduler. PROBLEM When we run Teamsite user administration command line tool IWUSERADM.exe though ASP.Net it gives following error: Application popup: cmd.exe - Application Error : The application failed to initialize properly (0xc0000142). Click on OK to terminate the application. CAUSE No specific cause, it seems to be a bug, supposed to be resolved with this Microsoft patch http://support.microsoft.com/kb/960266. and there is nothing related to permission issue, y web application is impersonated with an administrator account. off course running a bat file from dmin account is a potential secury threat but for this scenario lets conifned our discussion to run the command line tool. RESOLUTION I have not tried this patch as I have not permitted to run this patch on server. Below are the steps to achive the requirement. 1/ Create a batch file which runs the IWUSERADM.exe.         echo - Add Teamsite User    CD E:\Appli\GN00\iw-home\bin    iwuseradm add-user %1 2/ Temporarily create a schedule task and run  the .bat file by scheduled task by ASP.Net code using TaskScheduler http://www.codeproject.com/KB/cs/tsnewlib.aspx. 3/ Here is the function: private int AddTeamsiteUser(string strBatchFilePath, string strUser) { //Get a ScheduledTasks object for the local computer. ScheduledTasks st = new ScheduledTasks(); // Create a task Task t; try{ t = st.CreateTask("~AddTeamsiteUser"); } catch { throw new Exception("Schedule Task ~AddTeamsiteUser already exist."); }    t.SetAccountInformation(yourLogin, yourPassword); //Set the account under which the task should run.  t.Save();  t.Run(); Thread.Sleep(2000); //for sync issue //Remove the scheduled task st.DeleteTask("~AddTeamsiteUser"); return t.ExitCode;   Below are few resources related to the above scenario:- - Task Scheduler Class Library for .NET  http://www.codeproject.com/KB/cs/tsnewlib.aspx - Run a .BAT file from ASP.NET  http://codebetter.com/blogs/brendan.tompkins/archive/2004/05/13/13484.aspx - TaskScheduler Class  http://msdn.microsoft.com/en-us/library/system.threading.tasks.taskscheduler.aspx - Application Hangs whle running iwuseradm.exe through ASP.Net  http://bytes.com/topic/asp-net/answers/733098-system-diagnostics-process-hangs     t.ApplicationName = strBatchFilePath; t.Parameters = strUser; t.Comment = "Adding user to Teamsite Application"

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• How can I convince cowboy programmers to use source control?

  - by P.Brian.Mackey

  UPDATE I work on a small team of devs, 4 guys. They have all used source control. Most of them can't stand source control and instead choose not to use it. I strongly believe source control is a necessary part of professional development. Several issues make it very difficult to convince them to use source control: The team is not used to using TFS. I've had 2 training sessions, but was only allotted 1 hour which is insufficient. Team members directly modify code on the server. This keeps code out of sync. Requiring comparison just to be sure you are working with the latest code. And complex merge problems arise Time estimates offered by developers exclude time required to fix any of these problems. So, if I say nono it will take 10x longer...I have to constantly explain these issues and risk myself because now management may perceive me as "slow". The physical files on the server differ in unknown ways over ~100 files. Merging requires knowledge of the project at hand and, therefore, developer cooperation which I am not able to obtain. Other projects are falling out of sync. Developers continue to have a distrust of source control and therefore compound the issue by not using source control. Developers argue that using source control is wasteful because merging is error prone and difficult. This is a difficult point to argue, because when source control is being so badly mis-used and source control continually bypassed, it is error prone indeed. Therefore, the evidence "speaks for itself" in their view. Developers argue that directly modifying server code, bypassing TFS saves time. This is also difficult to argue. Because the merge required to synchronize the code to start with is time consuming. Multiply this by the 10+ projects we manage. Permanent files are often stored in the same directory as the web project. So publishing (full publish) erases these files that are not in source control. This also drives distrust for source control. Because "publishing breaks the project". Fixing this (moving stored files out of the solution subfolders) takes a great deal of time and debugging as these locations are not set in web.config and often exist across multiple code points. So, the culture persists itself. Bad practice begets more bad practice. Bad solutions drive new hacks to "fix" much deeper, much more time consuming problems. Servers, hard drive space are extremely difficult to come by. Yet, user expectations are rising. What can be done in this situation?

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• AWS .NET SDK v2: the message-pump pattern

  - by Elton Stoneman

  Originally posted on: http://geekswithblogs.net/EltonStoneman/archive/2013/10/11/aws-.net-sdk-v2--the-message-pump-pattern.aspxVersion 2 of the AWS SDK for .NET has had a few pre-release iterations on NuGet and is stable, if a bit lacking in step-by-step guides. There’s at least one big reason to try it out: the SQS queue client now supports asynchronous reads, so you don’t need a clumsy polling mechanism to retrieve messages. The new approach  is easy to use, and lets you work with AWS queues in a similar way to the message-pump pattern used in the latest Azure SDK for Service Bus queues and topics. I’ve posted a simple wrapper class for subscribing to an SQS hub on gist here: A wrapper for the SQS client in the AWS SDK for.NET v2, which uses the message-pump pattern. Here’s the core functionality in the subscribe method: private async void Subscribe() { if (_isListening) { var request = new ReceiveMessageRequest { MaxNumberOfMessages = 10 }; request.QueueUrl = QueueUrl; var result = await _sqsClient.ReceiveMessageAsync(request, _cancellationTokenSource.Token); if (result.Messages.Count > 0) { foreach (var message in result.Messages) { if (_receiveAction != null && message != null) { _receiveAction(message.Body); DeleteMessage(message.ReceiptHandle); } } } } if (_isListening) { Subscribe(); } } which you call with something like this: client.Subscribe(x=>Log.Debug(x.Body)); The async SDK call returns when there is something in the queue, and will run your receive action for every message it gets in the batch (defaults to the maximum size of 10 messages per call). The listener will sit there awaiting messages until you stop it with: client.Unsubscribe(); Internally it has a cancellation token which it sets when you call unsubscribe, which cancels any in-flight call to SQS and stops the pump. The wrapper will also create the queue if it doesn’t exist at runtime. The Ensure() method gets called in the constructor so when you first use the client for a queue (sending or subscribing), it will set itself up: if (!Exists()) { var request = new CreateQueueRequest(); request.QueueName = QueueName; var response = _sqsClient.CreateQueue(request); QueueUrl = response.QueueUrl; } The Exists() check has to do make a call to ListQueues on the SNS client, as it doesn’t provide its own method to check if a queue exists. That call also populates the Amazon Resource Name, the unique identifier for this queue, which will be useful later. To use the wrapper, just instantiate and go: var queueClient = new QueueClient(“ProcessWorkflow”); queueClient.Subscribe(x=>Log.Debug(x.Body)); var message = {}; //etc. queueClient.Send(message);

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• What is a resonable workflow for designing webapps?

  - by Evan Plaice

  It has been a while since I have done any substantial web development and I'd like to take advantage of the latest practices but I'm struggling to visualize the workflow to incorporate everything. Here's what I'm looking to use: CakePHP framework jsmin (JavaScript Minify) SASS (Synctactically Awesome StyleSheets) Git CakePHP: Pretty self explanatory, make modifications and update the source. jsmin: When you modify a script, do you manually run jsmin to output the new minified code, or would it be better to run a pre-commit hook that automatically generates jsmin outputs of javascript files that have changed. Assume that I have no knowledge of implementing commit hooks. SASS: I really like what SASS has to offer but I'm also aware that SASS code isn't supported by browsers by default so, at some point, the SASS code needs to be transformed to normal CSS. At what point in the workflow is this done. Git I'm terrified to admit it but, the last time I did any substantial web development, I didn't use SCM source control (IE, I did use source control but it consisted of a very detailed change log with backups). I have since had plenty of experience using Git (as well as mercurial and SVN) for desktop development but I'm wondering how to best implement it for web development). Is it common practice to implement a remote repository on the web host so I can push the changes directly to the production server, or is there some cross platform (windows/linux) tool that makes it easy to upload only changed files to the production server. Are there web hosting companies that make it eas to implement a remote repository, do I need SSH access, etc... I know how to accomplish this on my own testing server with a remote repository with a separate remote tracking branch already but I've never done it on a remote production web hosting server before so I'm not aware of the options yet. Extra: I was considering implementing a javascript framework where separate javascript files used on a page are compiled into a single file for each page on the production server to limit the number of file downloads needed per page. Does something like this already exist? Is there already an open source project out in the wild that implements something similar that I could use and contribute to? Considering how paranoid web devs are about performance (and the fact that the number of file requests on a website is a big hit to performance) I'm guessing that there is some wizard hacker on the net who has already addressed this issue.

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• InvokeRequired not reliable?

  - by marocanu2001

  InvalidOperationException: Cross-thread operation not valid: Control 'progressBar' accessed from a thread other than the thread it was created ... Now this is not a nice way to start a day! not even if it's a Monday! So you have seen this and already thought, come on, this is an old one, just ask whether InvokeRequired before calling the method in the control, something like this: if (progressBar.InvokeRequired) {           progressBar.Invoke  ( new MethodInvoker( delegate {  progressBar.Value = 50;    }) ) }else      progressBar.Value = 50;    Unfortunately this was not working the way I would have expected, I got this error, debugged and though in debugging the InvokeRequired had become true , the error was thrown on the branch that did not required Invoke. So there was a scenario where InvokeRequired returned false and still accessing the control was not on the right thread ... Problem was that I kept showing and hiding the little form showing the progressbar. The progressbar was updating on an event  , ProgressChanged and I could not guarantee the little form was loaded by the time the event was thrown. So , spotted the problem, if none of the parents of the control you try to modify is created at the time of the method invoking, the InvokeRequired returns true! That causes your code to execute on the woring thread. Of course, updating UI before the win dow was created is not a legitimate action either, still I would have expected a different error. MSDN: "If the control's handle does not yet exist, InvokeRequired searches up the control's parent chain until it finds a control or form that does have a window handle. If no appropriate handle can be found, the InvokeRequired method returns false. This means that InvokeRequired can return false if Invoke is not required (the call occurs on the same thread), or if the control was created on a different thread but the control's handle has not yet been created." Have  a look at InvokeRequired's implementation: public bool InvokeRequired {     get     {         HandleRef hWnd;         int lpdwProcessId;         if (this.IsHandleCreated)         {             hWnd = new HandleRef(this, this.Handle);         }         else         {             Control wrapper = this.FindMarshallingControl();             if (!wrapper.IsHandleCreated)             {                 return false; // <==========             }             hWnd = new HandleRef(wrapper, wrapper.Handle);         }         int windowThreadProcessId = SafeNativeMethods.GetWindowThreadProcessId(hWnd, out lpdwProcessId);         int currentThreadId = SafeNativeMethods.GetCurrentThreadId();         return (windowThreadProcessId != currentThreadId);     } } Here 's a good article about this and a workaround http://www.ikriv.com/en/prog/info/dotnet/MysteriousHang.html

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• ETPM Environment Health Monitoring Tools

  - by Paula Speranza-Hadley

  This post is to provide some useful information about the tools typically used by Oracle ETPM implementations for performance tuning and analysis.   This includes tools to monitor and gather performance information and statistics on the Database, Application Server, and Client (browser).  Enterprise Monitoring Tools Oracle Enterprise Manager - OEM Grid Control comes with a comprehensive set of performance and health metrics that allow monitoring of key components in your environment such as applications, application servers, databases, as well as the back-end components on which they rely, such as hosts, operating systems and storage. Tools for the Database Oracle Diagnostics Pack Automatic Workload Repository (AWR)  - this tool gets statistics from memory abut the Time Model or DB Time, Wait Events, Active Session History and High Load SWL queries Automatic Database Diagnostic Monitor (ADDM) - This self-diagnostic software is built into the database.  It examines and analyzes data captured in AWR to dertermine possible performance issues.  It locates the root cause of the issue, provides recommendations for correcting the issues and qualifies the expected benefit. Oracle Database Tuning Pack SQL Tuning Advisor - This enables you to submit one or more SQL statements as input and receive output in the form of specific advice or recommendations on how to tune statements.  The recommendation relates to collection of statistics on objects, creation on new indexes and restructuring of SQL statements. SQL Access Advisor - This enables you to optimize data access paths of SQL queries by recommending a proper set of materialized views, indexes and partitions for a given SQL workload. Tools for the Application Server Weblogic Console - is a web-based, user interface used to configure and control a set of WebLogic servers or clusters (i.e. a "domain").  In any logical group of WebLogic servers there must exist one admin server, which hosts the WebLogic Admin console application and manages the associated configuratoin files. WebLogic Administrators will use the Administration Console for a number of tasks, including: Starting and stopping WebLogic servers or entire clusters. Configuring server parameters, security, database connections and deployed applications. Viewing server status, health and metrics. Yourkit for Profiling - helps analyze synchronization issues, including: Which threads were calling wait(), and for how long Which threads were blocked on attempt to acquire a monitor held by another thread (synchronized methods/blocks), and for how long Tools for the Client Fiddler - allows you to inspect traffic logs, debug and set breakpoints. Firebug – allows you to inspect and edit HTML, monitor network activity and debug JavaScript

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• WNA Configuration in OAM 11g

  - by P Patra

  Pre-Requisite: Kerberos authentication scheme has to exist. This is usually pre-configured OAM authentication scheme. It should have Authentication Level - "2", Challenge Method - "WNA", Challenge Direct URL - "/oam/server" and Authentication Module- "Kerberos". The default authentication scheme name is "KerberosScheme", this name can be changed. The DNS name has to be resolvable on the OAM Server. The DNS name with referrals to AD have to be resolvable on OAM Server. Ensure nslookup work for the referrals. Pre-Install: AD team to produce keytab file on the AD server by running ktpass command. Provide OAM Hostname to AD Team. Receive from AD team the following: Keypass file produced when running the ktpass command ktpass username ktpass password Copy the keytab file to convenient location in OAM install tree and rename the file if desired. For instance where oam-policy.xml file resides. i.e. /fa_gai2_d/idm/admin/domains/idm-admin/IDMDomain/config/fmwconfig/keytab.kt Configure WNA Authentication on OAM Server: Create config file krb.config and set the environment variable to the path to this file: KRB_CONFIG=/fa_gai2_d/idm/admin/domains/idm-admin/IDMDomain/config/fmwconfig/krb.conf The variable KRB_CONFIG has to be set in the profile for the user that OAM java container(i.e. Wbelogic Server) runs as, so that this setting is available to the OAM server. i.e. "applmgr" user. In the krb.conf file specify: [libdefaults] default_realm= NOA.ABC.COM dns_lookup_realm= true dns_lookup_kdc= true ticket_lifetime= 24h forwardable= yes [realms] NOA.ABC.COM={ kdc=hub21.noa.abc.com:88 admin_server=hub21.noa.abc.com:749 default_domain=NOA.ABC.COM [domain_realm] .abc.com=ABC.COM abc.com=ABC.COM .noa.abc.com=NOA.ABC.COM noa.abc.com=NOA.ABC.COM Where hub21.noa.abc.com is load balanced DNS VIP name for AD Server and NOA.ABC.COM is the name of the domain. Create authentication policy to WNA protect the resource( i.e. EBSR12) and choose the "KerberosScheme" as authentication scheme. Login to OAM Console => Policy Configuration Tab => Browse Tab => Shared Components => Application Domains => IAM Suite => Authentication Policies => Create Name: ABC WNA Auth Policy Authentication Scheme: KerberosScheme Failure URL: http://hcm.noa.abc.com/cgi-bin/welcome Edit System Configuration for Kerberos System Configuration Tab => Access Manager Settings => expand Authentication Modules => expand Kerberos Authentication Module => double click on Kerberos Edit "Key Tab File" textbox - put in /fa_gai2_d/idm/admin/domains/idm-admin/IDMDomain/config/fmwconfig/keytab.kt Edit "Principal" textbox - put in HTTP/[email protected] Edit "KRB Config File" textbox - put in /fa-gai2_d/idm/admin/domains/idm-admin/IDMDomain/config/fmwconfig/krb.conf Cilck "Apply" In the script setting environment for the WLS server where OAM is deployed set the variable: KRB_CONFIG=/fa_gai2_d/idm/admin/domains/idm-admin/IDMDomain/config/fmwconfig/krb.conf Re-start OAM server and OAM Server Container( Weblogic Server)

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• When to use HTTP status code 404 in an API

  - by Sybiam

  I am working on a project and after arguing with people at work for about more than a hour. I decided to know what people on stack-exchange might say. We're writing an API for a system, there is a query that should return a tree of Organization or a tree of Goals. The tree of Organization is the organization in which the user is present, In other words, this tree should always exists. In the organization, a tree of goal should be always present. (that's where the argument started). In case where the tree doesn't exist, my co-worker decided that it would be right to answer response with status code 200. And then started asking me to fix my code because the application was falling apart when there is no tree. I'll try to spare flames and fury. I suggested to raise a 404 error when there is no tree. It would at least let me know that something is wrong. When using 200, I have to add special check to my response in the success callback to handle errors. I'm expecting to receive an object, but I may actually receive an empty response because nothing is found. It sounds totally fair to mark the response as a 404. And then war started and I got the message that I didn't understand HTTP status code schema. So I'm here and asking what's wrong with 404 in this case? I even got the argument "It found nothing, so it's right to return 200". I believe that it's wrong since the tree should be always present. If we found nothing and we are expecting something, it should be a 404. More info, I forgot to add the urls that are fetched. Organizations /OrgTree/Get Goals /GoalTree/GetByDate?versionDate=... /GoalTree/GetById?versionId=... My mistake, both parameters are required. If any versionDate that can be parsed to a date is provided, it will return the closes revision. If you enter something in the past, it will return the first revision. If by Id with a id that doesn't exists, I suspect it's going to return an empty response with 200. Extra Also, I believe the best answer to the problem is to create default objects when organizations are created, having no tree shouldn't be a valid case and should be seen as an undefined behavior. There is no way an account can be used without both trees. For that reasons, they should be always present. also I got linked this (one similar but I can't find it) http://viswaug.files.wordpress.com/2008/11/http-headers-status1.png

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• Turn off keyboard back-light Sony (VAIO SVF1521DCXW)

  - by KasiyA

  I have a Sony laptop and I want to turn keyboard back-light off. It doesn't have a shortcut function key for doing this on the keyboard . I can turn off it with VAIO Control Center in Windows but I don't know how can I turn it off in Ubuntu 14.04. There isn't available to me: /sys/devices/platform/sony-laptop/kbd_backlight doesn't exist on my machine. I have this folder /sys/devices/platform/sony-laptop/ and there is three folder one power folder and two shortcut-ed folder driver , subsystem and five file contains battery_care_health , battery_care_limiter , modalias , touchpad and event This is the output of running sudo modinfo sony-laptop: filename: /lib/modules/3.13.0-34-generic/kernel/drivers/platform/x86/sony-laptop.ko version: 0.6 license: GPL description: Sony laptop extras driver (SPIC and SNC ACPI device) author: Stelian Pop, Mattia Dongili srcversion: 5C6E050349475558A231C59 alias: acpi*:SNY6001:* alias: acpi*:SNY5001:* depends: intree: Y vermagic: 3.13.0-34-generic SMP mod_unload modversions signer: Magrathea: Glacier signing key sig_key: 50:0B:C5:C8:7D:4B:11:5C:F3:C1:50:4F:7A:92:E2:33:C6:14:3D:58 sig_hashalgo: sha512 parm: debug:set this to 1 (and RTFM) if you want to help the development of this driver (int) parm: no_spic:set this if you don't want to enable the SPIC device (int) parm: compat:set this if you want to enable backward compatibility mode (int) parm: mask:set this to the mask of event you want to enable (see doc) (ulong) parm: camera:set this to 1 to enable Motion Eye camera controls (only use it if you have a C1VE or C1VN model) (int) parm: minor:minor number of the misc device for the SPIC compatibility code, default is -1 (automatic) (int) parm: kbd_backlight:set this to 0 to disable keyboard backlight, 1 to enable it (default: no change from current value) (int) parm: kbd_backlight_timeout:meaningful values vary from 0 to 3 and their meaning depends on the model (default: no change from current value) (int) With the suggested command: sudo modprobe -r sony_laptop sudo modprobe -v sony_laptop kbd_backlight=0 Output was: insmod /lib/modules/3.13.0-34-generic/kernel/drivers/platform/x86/sony-laptop.ko kbd_backlight=0 It doesn't seem to affect the keyboard backlight. And also trying this command: sudo modprobe -v sony_laptop kbd_backlight_timeout=3 kbd_backlight=0 and doesn't seem to effect the keyboard backlight I also test it after restart laptop, And I didn't see any effect too. Important : By default, keyboard backlight is off; when I press a key it turns on and after 15 seconds it turns off again. It's the same result on battery and AC power I followed also http://ubuntuforums.org/showthread.php?t=2139597 and Keyboard backlighting not working on a Vaio VPCSB11FX but didn't work so.

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• Overload Avoidance

  - by mikef

  A little under a year ago, Matt Simmons wrote a rather reflective article about his terrifying brush with stress-induced ill health. SysAdmins and DBAs have always been prime victims of work-related stress, but I wonder if that predilection is perhaps getting worse, despite the best efforts of Matt and his trusty side-kick, HR. The constant pressure from share-holders and CFOs to 'streamline' the workforce is partially to blame, but the more recent culprit is technology itself. I can't deny that the rise of technologies like virtualization, PowerCLI, PowerShell, and a host of others has been a tremendous boon. As a result, individual IT professionals are now able to handle more and more tasks and manage increasingly large and complex environments. But, without a doubt, this is a two-edged sword; The reward for competence is invariably more work. Unfortunately, SysAdmins play such a pivotal role in modern business that it's easy to see how they can very quickly become swamped in conflicting demands coming from different directions. However, that doesn't justify the ridiculous hours many are asked (or volunteer) to devote to their work. Admirably though their commitment is, it isn't healthy for them, it sets a dangerous expectation, and eventually something will snap. There are times when everyone needs to step up to the plate outside of 'normal' work hours, but that time isn't all the time. Naturally, with all that lovely technology, you can automate more and more of those tricky tasks to keep on top of the workload, but you are still only human. Clever though you may be, there is a very real limit to how far technology can take you. I'm not suggesting that you avoid these technologies, or deliberately aim for mediocrity; I'm just saying that you need to be more than just technically skilled (and Wesley Nonapeptide riffs on and around this topic in his excellent 'Telepathic Robot Drones' blog post). You need to be able to manage expectations, not just Exchange. Specifically, that means your own expectations of what you are capable of, because those come before everyone else's. After all, how can you keep your work-life balance under control, if you're the one setting the bar way too high? Talking to your manager, or discussing issues with your users, is only going to be productive if you have some facts to work with. "Know Thyself" is the first law of managing work overload, and this is obviously a skill which people develop over time; the fact that veteran Sysadmins exist at all is testament to this. I'd just love to know how you get to that point. Personally, I'm using RescueTime to keep myself honest, but I'm open to recommendations for better methods. Do you track your own time, do you have an intuitive sense of what is possible, or do you just rely on someone else to handle that all for you? Cheers, Michael

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• GPL vs plugin interfaces not designed with a specific application in mind

  - by Kristóf Marussy

  I am not seeking or in need of legal advice, but an interesting though experiment came to my mind. Imagine the following situtation (I cannot really think about a concrete example and I am unsure if a real manifestation even exists): there is a free (libre) api A licensed under some permissive license or even LGPL. Non-free application B implements this api in order host plugins, but there are other free software doing the same thing. Moreover, there is plugin C acting as a plugin under api A. It links to library D, that is under GPL, so C is also under GPL. Plugins using A are loaded into hosts via a dlopen-like mechanism and use complex data structure for host-plugin communication. Neither B nor C distribute any files that may be required for A to function properly (like headers containing the structure definitions of A or dynamic libraries containing helper functions for A written by the authors of A), but such things may exist. Now some user installs application B and plugin C on his machine, along with anything that may be required for api A to function properly. Then he proceeds and loads C into B and creates some intellectual property with B which is not a piece of software. Did a GPL violation happend at some point, and if so, who violated GPL and why? The authors of C violate D's license by making C possible to be used in non-free host B? This is a possibility because they can't give and exception of GPL (like one described in http://www.gnu.org/licenses/gpl-faq.html#GPLPluginsInNF or http://www.gnu.org/licenses/gpl-faq.html#LinkingOverControlledInterface) due to D's license terms. The authors of B violate C's and D's license by making C possible to be loaded in B? This is a possibility because http://www.gnu.org/licenses/gpl-faq.html#NFUseGPLPlugins disallows the mechanisms A uses for communitation between the free and non-free modules. The authors of A, because the api may be used (and in this case, was used) for communication between GPL'd and non-free software. This would be extremely absurd. The user, because at the moment of loading B into C, he made a derived work of C. I think this is impossible, because he does not distribute it. But would the situation change is he decided to release a configuration file of B which makes B load C as a plugin? Nobody, because A counts as a 'system library', and both B and C directly interact only with A, not eachother. In a sane world, this would happen... A concrete example of A could be some kind of audio (think LADSPA) or image processing api. However, I could find no such interface (that is free software, generic and is also implemented by commercial tools). A real-world example could also be quite enlightening.

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• How to refactor a Python “god class”?

  - by Zearin

  Problem I’m working on a Python project whose main class is a bit “God Object”. There are so friggin’ many attributes and methods! I want to refactor the class. So Far… For the first step, I want to do something relatively simple; but when I tried the most straightforward approach, it broke some tests and existing examples. Basically, the class has a loooong list of attributes—but I can clearly look over them and think, “These 5 attributes are related…These 8 are also related…and then there’s the rest.” getattr I basically just wanted to group the related attributes into a dict-like helper class. I had a feeling __getattr__ would be ideal for the job. So I moved the attributes to a separate class, and, sure enough, __getattr__ worked its magic perfectly well… At first. But then I tried running one of the examples. The example subclass tries to set one of these attributes directly (at the class level). But since the attribute was no longer “physically located” in the parent class, I got an error saying that the attribute did not exist. @property I then read up about the @property decorator. But then I also read that it creates problems for subclasses that want to do self.x = blah when x is a property of the parent class. Desired Have all client code continue to work using self.whatever, even if the parent’s whatever property is not “physically located” in the class (or instance) itself. Group related attributes into dict-like containers. Reduce the extreme noisiness of the code in the main class. For example, I don’t simply want to change this: larry = 2 curly = 'abcd' moe = self.doh() Into this: larry = something_else('larry') curly = something_else('curly') moe = yet_another_thing.moe() …because that’s still noisy. Although that successfully makes a simply attribute into something that can manage the data, the original had 3 variables and the tweaked version still has 3 variables. However, I would be fine with something like this: stooges = Stooges() And if a lookup for self.larry fails, something would check stooges and see if larry is there. (But it must also work if a subclass tries to do larry = 'blah' at the class level.) Summary Want to replace related groups of attributes in a parent class with a single attribute that stores all the data elsewhere Want to work with existing client code that uses (e.g.) larry = 'blah' at the class level Want to continue to allow subclasses to extend, override, and modify these refactored attributes without knowing anything has changed Is this possible? Or am I barking up the wrong tree?

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• Wordpress Installation (on IIS and SQL Server)

  - by Davide Mauri

  To proceed with the installation of Wordpress on SQL Server and IIS, first of all, you need to do the following steps Create a database on SQL Server that will be used by Wordpress Create login that can access to the just created database and put the user into ddladmin, db_datareader, db_datawriter roles Download and unpack Wordpress 3.3.2 (latest version as of 27 May 2012) zip file into a directory of your choice Download the wp-db-abstraction 1.1.4 (latest version as of 27 May 2012) plugin from wordpress.org website Now that the basic action has been done, you can start to setup and configure your Wordpress installation. Unpack and follow the instructions in the README.TXT file to install the Database Abstraction Layer. Mainly you have to: Upload wp-db-abstraction.php and the wp-db-abstraction directory to wp-content/mu-plugins.  This should be parallel to your regular plugins directory.  If the mu-plugins directory does not exist, you must create it. Put the db.php file from inside the wp-db-abstraction.php directory to wp-content/db.php Now you can create an application pool in IIS like the following one Create a website, using the above Application Pool, that points to the folder where you unpacked Wordpress files. Be sure to give the “Write” permission to the IIS account, as pointed out in this (old, but still quite valid) installation manual: http://wordpress.visitmix.com/development/installing-wordpress-on-sql-server#iis Now you’re ready to go. Point your browser to the configured website and the Wordpress installation screen will be there for you. When you’re requested to enter information to connect to MySQL database, simply skip that page, leaving the default values. If you have installed the Database Abstraction Layer, another database installation screen will appear after the one used by MySQL, and here you can enter the configuration information needed to connect to SQL Server. After having finished the installation steps, you should be able to access and navigate your wordpress site.  A final touch, and it’s done: just add the needed rewrite rules http://wordpress.visitmix.com/development/installing-wordpress-on-sql-server#urlrewrite and that’s it! Well. Not really. Unfortunately the current (as of 27 May 2012) version of the Database Abstraction Layer (1.1.4) has some bugs. Luckily they can be quickly fixed: Backslash Fix http://wordpress.org/support/topic/plugin-wp-db-abstraction-fix-problems-with-backslash-usage Select Top 0 Fix Make the change to the file “.\wp-content\mu-plugins\wp-db-abstraction\translations\sqlsrv\translations.php” suggested by “debettap”   http://sourceforge.net/tracker/?func=detail&aid=3485384&group_id=315685&atid=1328061 And now you have a 100% working Wordpress installation on SQL Server! Since I also wanted to take advantage of SQL Server Full Text Search, I’ve created a very simple wordpress plugin to setup full-text search and to use it as website search engine: http://wpfts.codeplex.com/ Enjoy!

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• MythTV lost recordings - "No recordings available" and no recording rules either

  - by nimasmi

  I have a c.6 year old mythtv database. I recently upgraded from Ubuntu 10.04 to 12.04. This brought a MythTV upgrade from 0.24 to 0.25, which went well. Today, all my recordings have disappeared. They still exist in the /var/lib/mythtv/recordings folder, and the 'M' key in the Watch Recordings page says that there are 201 recordings available somewhere, but they will not display. See screenshot: (implicit thanks to whomever upvoted this, giving me sufficient reputation to upload images) Changing the filter does not remedy the fact that there is nothing shown in the lists. My Upcoming Recordings screen says that there are no rules set, but my list of previously recorded shows is still there, and has an entry from as recently as 3am today. mythbackend --printsched gives the following: user@box:~$ mythbackend --printsched 2012-09-22 12:59:20.537008 C mythbackend version: fixes/0.25 [v0.25.2-15-g46cab93] www.mythtv.org 2012-09-22 12:59:20.537043 C Qt version: compile: 4.8.1, runtime: 4.8.1 2012-09-22 12:59:20.537048 N Enabled verbose msgs: general 2012-09-22 12:59:20.537076 N Setting Log Level to LOG_INFO 2012-09-22 12:59:20.537142 I Added logging to the console 2012-09-22 12:59:20.537152 I Added database logging to table logging 2012-09-22 12:59:20.537279 N Setting up SIGHUP handler 2012-09-22 12:59:20.537373 N Using runtime prefix = /usr 2012-09-22 12:59:20.537394 N Using configuration directory = /home/user/.mythtv 2012-09-22 12:59:20.537999 I Assumed character encoding: en_GB.UTF-8 2012-09-22 12:59:20.538599 N Empty LocalHostName. 2012-09-22 12:59:20.538610 I Using localhost value of box 2012-09-22 12:59:20.538792 I Testing network connectivity to '192.168.1.2' 2012-09-22 12:59:20.539420 I Starting process manager 2012-09-22 12:59:20.541412 I Starting IO manager (read) 2012-09-22 12:59:20.541715 I Starting IO manager (write) 2012-09-22 12:59:20.541836 I Starting process signal handler 2012-09-22 12:59:20.684497 N Setting QT default locale to EN_GB 2012-09-22 12:59:20.684694 I Current locale EN_GB 2012-09-22 12:59:20.684813 N Reading locale defaults from /usr/share/mythtv//locales/en_gb.xml 2012-09-22 12:59:20.697623 I New static DB connectionDataDirectCon 2012-09-22 12:59:20.704769 I MythCoreContext: Connecting to backend server: 192.168.1.2:6543 (try 1 of 1) Calculating Schedule from database. Inputs, Card IDs, and Conflict info may be invalid if you have multiple tuners. 2012-09-22 12:59:27.710538 E MythSocket(21dfcd0:14): readStringList: Error, timed out after 7000 ms. 2012-09-22 12:59:27.710592 C Protocol version check failure. The response to MYTH_PROTO_VERSION was empty. This happens when the backend is too busy to respond, or has deadlocked in due to bugs or hardware failure. Things I have tried so far: restart the backend restart the frontend run mythtv-setup and check database passwords and IP addresses change the frontend setting for backend IP from localhost to 192.168.1.2 (the backend/frontend's IP) run optimize_mythdb.pl Other suggestions appreciated.

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• Clone an Azure VM using Powershell

  - by jamiet

  In a few months time I will, in association with Technitrain, be running a training course entitled Introduction to SQL Server Data Tools. I am currently working on putting together some hands-on lab material for the course delegates and have decided that in order to save time in asking people to install software during the course I am simply going to prepare a virtual machine (VM) containing all the software and lab material for each delegate to use. Given that I am an MSDN subscriber it makes sense to use Windows Azure to host those VMs given that it will be close to, if not completely, free to do so. What I don’t want to do however is separately build a VM for each delegate, I would much rather build one VM and clone it for each delegate. I’ve spent a bit of time figuring out how to do this using Powershell and in this blog post I am sharing a script that will: Prompt for some information (Azure credentials, Azure subscription name, VM name, username & password, etc…) Create a VM on Azure using that information Prompt you to sysprep the VM and image it (this part can’t be done with Powershell so has to be done manually, a link to instructions is provided in the script output) Create three new VMs based on the image Remove those three VMs Simply download the script and execute it within Powershell, assuming you have an Azure account it should take about 20minutes to execute (spinning up VMs and shutting the down isn’t instantaneous). If you experience any issues please do let me know. There are additional notes below. Hope this is useful! @Jamiet  Notes: Obviously there isn’t a lot of point in creating some new VMs and then instantly deleting them. However, this demo script does provide everything you need should you want to do any of these operations in isolation. The names of the three VMs that get created will be suffixed with 001, 002, 003 but you can edit the script to call them whatever you like. The script doesn’t totally clean up after itself. If you specify a service name & storage account name that don’t already exist then it will create them however it won’t remove them when everything is complete. The created image file will also not be deleted. Removing these items can be done by visiting http://manage.windowsazure.com. When creating the image, ensure you use the correct name (the script output tells you what name to use): Here are some screenshots taken from running the script: When the third and final VM gets removed you are asked to confirm via this dialog: Select ‘Yes’

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• SQL SERVER – Concurrancy Problems and their Relationship with Isolation Level

  - by pinaldave

  Concurrency is simply put capability of the machine to support two or more transactions working with the same data at the same time. This usually comes up with data is being modified, as during the retrieval of the data this is not the issue. Most of the concurrency problems can be avoided by SQL Locks. There are four types of concurrency problems visible in the normal programming. 1)      Lost Update – This problem occurs when there are two transactions involved and both are unaware of each other. The transaction which occurs later overwrites the transactions created by the earlier update. 2)      Dirty Reads – This problem occurs when a transactions selects data that isn’t committed by another transaction leading to read the data which may not exists when transactions are over. Example: Transaction 1 changes the row. Transaction 2 changes the row. Transaction 1 rolls back the changes. Transaction 2 has selected the row which does not exist. 3)      Nonrepeatable Reads – This problem occurs when two SELECT statements of the same data results in different values because another transactions has updated the data between the two SELECT statements. Example: Transaction 1 selects a row, which is later on updated by Transaction 2. When Transaction A later on selects the row it gets different value. 4)      Phantom Reads – This problem occurs when UPDATE/DELETE is happening on one set of data and INSERT/UPDATE is happening on the same set of data leading inconsistent data in earlier transaction when both the transactions are over. Example: Transaction 1 is deleting 10 rows which are marked as deleting rows, during the same time Transaction 2 inserts row marked as deleted. When Transaction 1 is done deleting rows, there will be still rows marked to be deleted. When two or more transactions are updating the data, concurrency is the biggest issue. I commonly see people toying around with isolation level or locking hints (e.g. NOLOCK) etc, which can very well compromise your data integrity leading to much larger issue in future. Here is the quick mapping of the isolation level with concurrency problems: Isolation Dirty Reads Lost Update Nonrepeatable Reads Phantom Reads Read Uncommitted Yes Yes Yes Yes Read Committed No Yes Yes Yes Repeatable Read No No No Yes Snapshot No No No No Serializable No No No No I hope this 400 word small article gives some quick understanding on concurrency issues and their relation to isolation level. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Repository/Updating/Upgrading Issue

  - by Jakob

  The other day I was asked to upgrade from 13.04 to 13.10, at the time I was busy and hit no. I can not upgrade/update at this point, I get (error -11) or a 404 in terminal. In the software updater I get 'failed to download repository information.' I have tried changing my "Download From" setting to "Best" to "Main" and even a few other countries. And in "Other Software" I have tried disabling packages, but doesn't seem to help what so ever. I have tried several of the other commands to try and fix it, such as -fix missing or sudo apt-get update clean. P.S. This has also affected my thunderbird client, I cannot send/receive emails. Here is my error log when trying to upgrade: jakob@Skeletor:~$ sudo update-manager -d gpg: /tmp/tmpvejqvl/trustdb.gpg: trustdb created gpg: /tmp/tmpnayby6/trustdb.gpg: trustdb created Traceback (most recent call last): File "/usr/lib/python3/dist-packages/defer/__init__.py", line 483, in _inline_callbacks result = gen.throw(excep) File "/usr/lib/python3/dist-packages/UpdateManager/backend/InstallBackendAptdaemon.py", line 86, in commit True, close_on_done) File "/usr/lib/python3/dist-packages/defer/__init__.py", line 483, in _inline_callbacks result = gen.throw(excep) File "/usr/lib/python3/dist-packages/UpdateManager/backend/InstallBackendAptdaemon.py", line 158, in _run_in_dialog yield trans.run() aptdaemon.errors.TransactionFailed: Transaction failed: Package does not exist Package linux-headers-3.8.0-33 isn't available gpg: /tmp/tmp3kw_hl/trustdb.gpg: trustdb created. And let me throw in my sudo apt-get update too. Which this has been working variably too, but I don't know what to change my repositories to, and disabling does not effect: E: Some index files failed to download. They have been ignored, or old ones used instead. This is the short version, but looks exactly like this fairly consistently. Sometimes it downloads, sometimes it doesn't. Sometimes it tells me I have an update, and doesn't do anything. If it helps, I have recently had issues trying to install Samba as well, and connecting to the office's NAS Drive. Which works now, but I had to edit /etc/fstab/ and a few other things trying to get that to work as well. I understand it could also be a DNS problem, but this has been going on for a few days, as well as I've already tried changing my DNS server via my computer, however I am not allowed to alter the DNS on our company's router.

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