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  • What Counts For a DBA: Fitness

    - by Louis Davidson
    If you know me, you can probably guess that physical exercise is not really my thing. There was a time in my past when it a larger part of my life, but even then never in the same sort of passionate way as a number of our SQL friends.  For me, I find that mental exercise satisfies what I believe to be the same inner need that drives people to run farther than I like to drive on most Saturday mornings, and it is certainly just as addictive. Mental fitness shares many common traits with physical fitness, especially the need to attain it through repetitive training. I only wish that mental training burned off a bacon cheeseburger in the same manner as does jogging around a dewy park on Saturday morning. In physical training, there are at least two goals, the first of which is to be physically able to do a task. The second is to train the brain to perform the task without thinking too hard about it. No matter how long it has been since you last rode a bike, you will be almost certainly be able to hop on and start riding without thinking about the process of pedaling or balancing. If you’ve never ridden a bike, you could be a physics professor /Olympic athlete and still crash the first few times you try, even though you are as strong as an ox and your knowledge of the physics of bicycle riding makes the concept child’s play. For programming tasks, the process is very similar. As a DBA, you will come to know intuitively how to backup, optimize, and secure database systems. As a data programmer, you will work to instinctively use the clauses of Transact-SQL DML so that, when you need to group data three ways (and not four), you will know to use the GROUP BY clause with GROUPING SETS without resorting to a search engine.  You have the skill. Making it naturally then requires repetition and experience is the primary requirement, not just simply learning about a topic. The hardest part of being really good at something is this difference between knowledge and skill. I have recently taken several informative training classes with Kimball University on data warehousing and ETL. Now I have a lot more knowledge about designing data warehouses than before. I have also done a good bit of data warehouse designing of late and have started to improve to some level of proficiency with the theory. Yet, for all of this head knowledge, it is still a struggle to take what I have learned and apply it to the designs I am working on.  Data warehousing is still a task that is not yet deeply ingrained in my brain muscle memory. On the other hand, relational database design is something that no matter how much or how little I may get to do it, I am comfortable doing it. I have done it as a profession now for well over a decade, I teach classes on it, and I also have done (and continue to do) a lot of mental training beyond the work day. Sometimes the training is just basic education, some reading blogs and attending sessions at PASS events.  My best training comes from spending time working on other people’s design issues in forums (though not nearly as much as I would like to lately). Working through other people’s problems is a great way to exercise your brain on problems with which you’re not immediately familiar. The final bit of exercise I find useful for cultivating mental fitness for a data professional is also probably the nerdiest thing that I will ever suggest you do.  Akin to running in place, the idea is to work through designs in your head. I have designed more than one database system that would revolutionize grocery store operations, sales at my local Target store, the ordering process at Amazon, and ways to improve Disney World operations to get me through a line faster (some of which they are starting to implement without any of my help.) Never are the designs truly fleshed out, but enough to work through structures and processes.  On “paper”, I have designed database systems to catalog things as trivial as my Lego creations, rental car companies and my audio and video collections. Once I get the database designed mentally, sometimes I will create the database, add some data (often using Red-Gate’s Data Generator), and write a few queries to see if a concept was realistic, but I will rarely fully flesh out the database since I have no desire to do any user interface programming anymore.  The mental training allows me to keep in practice for when the time comes to do the work I love the most for real…even if I have been spending most of my work time lately building data warehouses.  If you are really strong of mind and body, perhaps you can mix a mental run with a physical run; though don’t run off of a cliff while contemplating how you might design a database to catalog the trees on a mountain…that would be contradictory to the purpose of both types of exercise.

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  • High Availability for IaaS, PaaS and SaaS in the Cloud

    - by BuckWoody
    Outages, natural disasters and unforeseen events have proved that even in a distributed architecture, you need to plan for High Availability (HA). In this entry I'll explain a few considerations for HA within Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS). In a separate post I'll talk more about Disaster Recovery (DR), since each paradigm has a different way to handle that. Planning for HA in IaaS IaaS involves Virtual Machines - so in effect, an HA strategy here takes on many of the same characteristics as it would on-premises. The primary difference is that the vendor controls the hardware, so you need to verify what they do for things like local redundancy and so on from the hardware perspective. As far as what you can control and plan for, the primary factors fall into three areas: multiple instances, geographical dispersion and task-switching. In almost every cloud vendor I've studied, to ensure your application will be protected by any level of HA, you need to have at least two of the Instances (VM's) running. This makes sense, but you might assume that the vendor just takes care of that for you - they don't. If a single VM goes down (for whatever reason) then the access to it is lost. Depending on multiple factors, you might be able to recover the data, but you should assume that you can't. You should keep a sync to another location (perhaps the vendor's storage system in another geographic datacenter or to a local location) to ensure you can continue to serve your clients. You'll also need to host the same VM's in another geographical location. Everything from a vendor outage to a network path problem could prevent your users from reaching the system, so you need to have multiple locations to handle this. This means that you'll have to figure out how to manage state between the geo's. If the system goes down in the middle of a transaction, you need to figure out what part of the process the system was in, and then re-create or transfer that state to the second set of systems. If you didn't write the software yourself, this is non-trivial. You'll also need a manual or automatic process to detect the failure and re-route the traffic to your secondary location. You could flip a DNS entry (if your application can tolerate that) or invoke another process to alias the first system to the second, such as load-balancing and so on. There are many options, but all of them involve coding the state into the application layer. If you've simply moved a state-ful application to VM's, you may not be able to easily implement an HA solution. Planning for HA in PaaS Implementing HA in PaaS is a bit simpler, since it's built on the concept of stateless applications deployment. Once again, you need at least two copies of each element in the solution (web roles, worker roles, etc.) to remain available in a single datacenter. Also, you need to deploy the application again in a separate geo, but the advantage here is that you could work out a "shared storage" model such that state is auto-balanced across the world. In fact, you don't have to maintain a "DR" site, the alternate location can be live and serving clients, and only take on extra load if the other site is not available. In Windows Azure, you can use the Traffic Manager service top route the requests as a type of auto balancer. Even with these benefits, I recommend a second backup of storage in another geographic location. Storage is inexpensive; and that second copy can be used for not only HA but DR. Planning for HA in SaaS In Software-as-a-Service (such as Office 365, or Hadoop in Windows Azure) You have far less control over the HA solution, although you still maintain the responsibility to ensure you have it. Since each SaaS is different, check with the vendor on the solution for HA - and make sure you understand what they do and what you are responsible for. They may have no HA for that solution, or pin it to a particular geo, or perhaps they have a massive HA built in with automatic load balancing (which is often the case).   All of these options (with the exception of SaaS) involve higher costs for the design. Do not sacrifice reliability for cost - that will always cost you more in the end. Build in the redundancy and HA at the very outset of the project - if you try to tack it on later in the process the business will push back and potentially not implement HA. References: http://www.bing.com/search?q=windows+azure+High+Availability  (each type of implementation is different, so I'm routing you to a search on the topic - look for the "Patterns and Practices" results for the area in Azure you're interested in)

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  • Microsoft Sql Server 2008 R2 System Databases

    For a majority of software developers little time is spent understanding the inner workings of the database management systems (DBMS) they use to store data for their applications.  I personally place myself in this grouping. In my case, I have used various versions of Microsoft’s SQL Server (2000, 2005, and 2008 R2) and just recently learned how valuable they really are when I was preparing to deliver a lecture on "SQL Server 2008 R2, System Databases". Microsoft Sql Server 2008 R2 System DatabasesSo what are system databases in MS SQL Server, and why should I know them? Microsoft uses system databases to support the SQL Server DBMS, much like a developer uses config files or database tables to support an application. These system databases individually provide specific functionality that allows MS SQL Server to function. Name Database File Log File Master master.mdf mastlog.ldf Resource mssqlsystemresource.mdf mssqlsystemresource.ldf Model model.mdf modellog.ldf MSDB msdbdata.mdf msdblog.ldf Distribution distmdl.mdf distmdl.ldf TempDB tempdb.mdf templog.ldf Master DatabaseIf you have used MS SQL Server then you should recognize the Master database especially if you used the SQL Server Management Studio (SSMS) to connect to a user created database. MS SQL Server requires the Master database in order for DBMS to start due to the information that it stores. Examples of data stored in the Master database User Logins Linked Servers Configuration information Information on User Databases Resource DatabaseHonestly, until recently I never knew this database even existed until I started to research SQL Server system databases. The reason for this is due largely to the fact that the resource database is hidden to users. In fact, the database files are stored within the Binn folder instead of the standard MS SQL Server database folder path. This database contains all system objects that can be accessed by all other databases.  In short, this database contains all system views and store procedures that appear in all other user databases regarding system information. One of the many benefits to storing system views and store procedures in a single hidden database is the fact it improves upgrading a SQL Server database; not to mention that maintenance is decreased since only one code base has to be mainlined for all of the system views and procedures. Model DatabaseThe Model database as the name implies is the model for all new databases created by users. This allows for predefining default database objects for all new databases within a MS SQL Server instance. For example, if every database created by a user needs to have an “Audit” table when it is  created then defining the “Audit” table in the model will guarantees that the table will be located in every new database create after the model is altered. MSDB DatabaseThe MSDBdatabase is used by SQL Server Agent, SQL Server Database Mail, SQL Server Service Broker, along with SQL Server. The SQL Server Agent uses this database to store job configurations and SQL job schedules along with SQL Alerts, and Operators. In addition, this database also stores all SQL job parameters along with each job’s execution history.  Finally, this database is also used to store database backup and maintenance plans as well as details pertaining to SQL Log shipping if it is being used. Distribution DatabaseThe Distribution database is only used during replication and stores meta data and history information pertaining to the act of replication data. Furthermore, when transactional replication is used this database also stores information regarding each transaction. It is important to note that replication is not turned on by default in MS SQL Server and that the distribution database is hidden from SSMS. Tempdb DatabaseThe Tempdb as the name implies is used to store temporary data and data objects. Examples of this include temp tables and temp store procedures. It is important to note that when using this database all data and data objects are cleared from this database when SQL Server restarts. This database is also used by SQL Server when it is performing some internal operations. Typically, SQL Server uses this database for the purpose of large sort and index operations. Finally, this database is used to store row versions if row versioning or snapsot isolation transactions are being used by SQL Server. Additionally, I would love to hear from others about their experiences using system databases, tables, and objects in a real world environments.

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  • Microsoft Sql Server 2008 R2 System Databases

    For a majority of software developers little time is spent understanding the inner workings of the database management systems (DBMS) they use to store data for their applications.  I personally place myself in this grouping. In my case, I have used various versions of Microsoft’s SQL Server (2000, 2005, and 2008 R2) and just recently learned how valuable they really are when I was preparing to deliver a lecture on "SQL Server 2008 R2, System Databases". Microsoft Sql Server 2008 R2 System DatabasesSo what are system databases in MS SQL Server, and why should I know them? Microsoft uses system databases to support the SQL Server DBMS, much like a developer uses config files or database tables to support an application. These system databases individually provide specific functionality that allows MS SQL Server to function. Name Database File Log File Master master.mdf mastlog.ldf Resource mssqlsystemresource.mdf mssqlsystemresource.ldf Model model.mdf modellog.ldf MSDB msdbdata.mdf msdblog.ldf Distribution distmdl.mdf distmdl.ldf TempDB tempdb.mdf templog.ldf Master DatabaseIf you have used MS SQL Server then you should recognize the Master database especially if you used the SQL Server Management Studio (SSMS) to connect to a user created database. MS SQL Server requires the Master database in order for DBMS to start due to the information that it stores. Examples of data stored in the Master database User Logins Linked Servers Configuration information Information on User Databases Resource DatabaseHonestly, until recently I never knew this database even existed until I started to research SQL Server system databases. The reason for this is due largely to the fact that the resource database is hidden to users. In fact, the database files are stored within the Binn folder instead of the standard MS SQL Server database folder path. This database contains all system objects that can be accessed by all other databases.  In short, this database contains all system views and store procedures that appear in all other user databases regarding system information. One of the many benefits to storing system views and store procedures in a single hidden database is the fact it improves upgrading a SQL Server database; not to mention that maintenance is decreased since only one code base has to be mainlined for all of the system views and procedures. Model DatabaseThe Model database as the name implies is the model for all new databases created by users. This allows for predefining default database objects for all new databases within a MS SQL Server instance. For example, if every database created by a user needs to have an “Audit” table when it is  created then defining the “Audit” table in the model will guarantees that the table will be located in every new database create after the model is altered. MSDB DatabaseThe MSDBdatabase is used by SQL Server Agent, SQL Server Database Mail, SQL Server Service Broker, along with SQL Server. The SQL Server Agent uses this database to store job configurations and SQL job schedules along with SQL Alerts, and Operators. In addition, this database also stores all SQL job parameters along with each job’s execution history.  Finally, this database is also used to store database backup and maintenance plans as well as details pertaining to SQL Log shipping if it is being used. Distribution DatabaseThe Distribution database is only used during replication and stores meta data and history information pertaining to the act of replication data. Furthermore, when transactional replication is used this database also stores information regarding each transaction. It is important to note that replication is not turned on by default in MS SQL Server and that the distribution database is hidden from SSMS. Tempdb DatabaseThe Tempdb as the name implies is used to store temporary data and data objects. Examples of this include temp tables and temp store procedures. It is important to note that when using this database all data and data objects are cleared from this database when SQL Server restarts. This database is also used by SQL Server when it is performing some internal operations. Typically, SQL Server uses this database for the purpose of large sort and index operations. Finally, this database is used to store row versions if row versioning or snapsot isolation transactions are being used by SQL Server. Additionally, I would love to hear from others about their experiences using system databases, tables, and objects in a real world environments.

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  • What Counts for a DBA: Humility

    - by drsql
    In football (the American sort, naturally,) there are a select group of players who really hope to never have their names called during the game. They are members of the offensive line, and their job is to protect other players so they can deliver the ball to the goal to score points. When you do hear their name called, it is usually because they made a mistake and the player that they were supposed to protect ended up flat on his back admiring the clouds in the sky instead of advancing towards the goal to scoring point. Even on the rare occasion their name is called for a good reason, it is usually because they were making up for a teammate who had made a mistake and they covered up for them. The role of offensive lineman is a very good analogy for the role of the admin DBA. As a DBA, you are called on to be barely visible and rarely heard, protecting the company data assets tenaciously, even though the enemies to our craft surround us on all sides:. Developers: Cries of ‘foul!’ often ensue when the DBA says that they want data integrity to be stringently enforced and that documentation is needed so they can support systems, mostly because every error occurrence in the enterprise will be initially blamed on the database and fall to the DBA to troubleshoot. Insisting too loudly may bring those cries of ‘foul’ that somewhat remind you of when your 2 year old daughter didn't want to go to bed. The result of this petulance is that the next "enemy" gets involved. Managers: The concerns that motivate DBAs to argue will not excite the kind of manager who gets his technical knowledge from a glossy magazine filled with buzzwords, charts, and pretty pictures. However, the other programmers in the organization will tickle the buzzword void with a stream of new-sounding ideas and technologies constantly, along with warnings that if we did care about data integrity and document things, the budget would explode! In contrast, the arguments for integrity of data and supportability tend to be about as exciting as watching grass grow, and far too many manager types seem to prefer to smoke it than watch it. Packaged Applications: The DBA is rarely given a chance to review a new application that is being demonstrated for the enterprise, and rarer still is the DBA that gets a veto of an application because the database it uses has clearly been created by an architect that won't read a data modeling book because he is already married. More often than not this leads to hours of work for the DBA trying to performance-tune a database with a menagerie of rules that must be followed to stay within the  application support agreement, such as no changing indexes on a third party schema even though there are 10 billion rows instead of the 10 thousand when the system was last optimized. Hardware Failures: Physical disks, networking devices, memory, and backup devices all come with a measure known as ‘mean time before failure’ and it is never listed in centuries or eons. More like years, and the term ‘mean’ indicates that half of the devices are expected to fail before that, which by my calendar means any hour of any day that it wants to fail it will. But the DBA sucks it up and does the task at hand with a humility that makes them nearly invisible to all but the most observant person in the organization. The best DBAs I know are so proactive in their relentless pursuit of perfection that they detect many of the bugs (which they seldom caused) in the system well before they become a problem. In the end the DBA gets noticed for one of same two reasons as the offensive lineman. You make a mistake, like dropping a critical production database that had never been backed up; or when a system crashes for any reason whatsoever and they are on the spot with troubleshooting and system restoration plans that have been well thought out, tested, and tested again. Not because there is any glory in it, but because it is what they do.   Note: The characteristics of the professions referred to in this blog are meant to be overstated stereotypes for humorous effect, and even some DBAs aren't quite this perfect. If you are reading this far and haven’t hand written a 10 page flaming comment about how you are a _______ and you aren’t like this, that is awesome. Not every situation applies to everyone, but if you have never worked with a bad packaged app, a magazine trained manager, programmers that aren’t team players, or hardware that occasionally failed, relax and go have a unicorn sandwich before you wake up.

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  • jQuery: How to check if a value exists in an array?

    - by Jannis
    Hello, I am trying to write a simple input field validation plugin at the moment (more of a learning exercise really) and thought this would not be too hard, seeing as all I should have to do is: Get input fields Store them in array with each one's value On submit of form check if array contains any empty strings But I seem to fail at writing something that checks for an empty string (read: input with no text inside) inside my array. Here is the code I have so far: var form = $(this), // passed in form element inputs = form.find('input'), // all of this forms input fields isValid = false; // initially set the form to not be valid function validate() { var fields = inputs.serializeArray(); // make an array out of input fields // start -- this does not work for (var n in fields) { if (fields[n].value == "") { isValid = false; console.log('failed'); } else { isValid = true; console.log('passed'); }; } // end -- this does not work }; // close validate() // TRIGGERS inputs.live('keyup blur', function(event) { validate(); }); Any help with how I can check if one of the fields is blank and if so return a isValid = false would be much appreciated. I also played around with the $.inArray("", fields) but this would never return 0 or 1 even when the console.log showed that the fields had no value. Thanks for reading.

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  • Extending Programming Languages

    - by chpwn
    (Since I just posted this in another question, but my browser had to be annoying and submit it without content first, here it is again:) I'm a fan of clean code. I like my languages to be able to express what I'm trying to do, but I like the syntax to mirror that too. For example, I work on a lot of programs in Objective-C for jailbroken iPhones, which patch other code using the method_setImplementation() function of the runtime. Or, in pyobjc, I have to use the syntax UIView.initWithFrame_(), which is also pretty awful and unreadable with the way the method names are structured. In both cases, the language does not support this in syntax. I've found three basic ways that this is done: Insane macros. Take a look at this "CaptainHook", it does what I'm looking for in a usable way, but it isn't quite clean and is a major hack. There's also "Logos", which implements a very nice syntax, but is written in Perl parsing my code with a ton of regular expressions. This scares me. I like the idea of adding a %hook ClassName, but not by using regular expressions to parse C or Objective-C. Finally, there is Cycript. This is an extension to JavaScript which interfaces with the Objective-C runtime and allows you to use Objective-C style code in your JavaScript, and inject that into other processes. This is likely the cleanest as it actually uses a parser for the JavaScript, but I'm not a huge fan of that language in general. Basically, this is a two part question. Should, and how should, I create an extension to Python and Objective-C to allow me to do this? Is it worth writing a parser for my language to transform the syntax into something nicer, if it is only in a very specialized niche like this? Should I just live with the horrible syntax of the default Objective-C hooking or pyobjc?

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  • Select videos using UIImagePickerController in 2G/3G

    - by Raj
    Hi, I am facing a problem where-in I cannot select videos from the photo album in iPhone 2G/3G device. The default photos application does show videos and is capable of playing them, which in turn means that UIImagePickerController should clearly be capable of showing videos in photo album and selecting them. I have coded this to determine whether the device is capable of snapping a photo, recording video, selecting photos and selecting videos: // Check if camera and video recording are available: [self setCameraAvailable:NO]; [self setVideoRecordingAvailable:NO]; [self setPhotoSelectionAvailable:NO]; [self setVideoSelectionAvailable:NO]; // For live mode: NSArray *availableTypes = [UIImagePickerController availableMediaTypesForSourceType:UIImagePickerControllerSourceTypeCamera]; NSLog(@"Available types for source as camera = %@", availableTypes); if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) { if ([availableTypes containsObject:(NSString*)kUTTypeMovie]) [self setVideoRecordingAvailable:YES]; if ([availableTypes containsObject:(NSString*)kUTTypeImage]) [self setCameraAvailable:YES]; } // For photo library mode: availableTypes = [UIImagePickerController availableMediaTypesForSourceType:UIImagePickerControllerSourceTypePhotoLibrary]; NSLog(@"Available types for source as photo library = %@", availableTypes); if ([availableTypes containsObject:(NSString*)kUTTypeImage]) [self setPhotoSelectionAvailable:YES]; if ([availableTypes containsObject:(NSString*)kUTTypeMovie]) [self setVideoSelectionAvailable:YES]; The resulting logs for 3G device is as follows: 2010-05-03 19:09:09.623 xyz [348:207] Available types for source as camera = ( "public.image" ) 2010-05-03 19:09:09.643 xyz [348:207] Available types for source as photo library = ( "public.image" ) As the logs state, for photo library the string equivalent of kUTTypeMovie is not available and hence the UIImagePickerController does not show up (or rather throws exception if we set the source types array which includes kUTTypeMovie) the movie files in photo library. I havent tested for 3GS, but I am sure that this problem does not exist in it with reference to other threads. I have built the app for both 3.0 (base SDK) and 3.1 but with the same results. This issue is already discussed in the thread: http://www.iphonedevsdk.com/forum/iphone-sdk-development/36197-uiimagepickercontroller-does-not-show-movies-albums.html But it does not seem to host a solution. Any solutions to this problem? Thanks and Regards, Raj Pawan

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  • IIS7 Mixed Mode Authentication

    - by drachenstern
    We're getting ready to start migrating some of our IIS6 sites to IIS7, and the application currently uses Forms Authentication. We have started getting some requests from various sites to use the Windows Authentication for the users. While this is easy enough to implement (and I've shown internally that there is no issue with the app, as expected) the question then is how to continue to keep Forms authentication for when Integrated Windows doesn't work. I've seen several walkthroughs on how to have it configured on IIS6, and I could do the same thing on IIS7, but then I have to turn on Classic Mode processing. Any solution should also be back portable to IIS6, if possible, to keep the build tree simple. So what are my options on this? Do I setup the app with Integrated Windows Authentication in IIS7, Forms Auth in the web.config, and redirect 401 errors to an "error page" allowing them to login using forms, then back to the regular app? The case when Forms is likely to be needed is going to be reserved for Contract workers, our support staff, and if someone needs to access it on their site from their Extranet. So primarily it's for our staff to login to check functionality and confirm bug reports. I suggested we just maintain that for our support staff to work, we need a Windows login that will always be live, and then we'll just enforce local responsibility on who can login to the site, but I'm told that we would do better to have Forms Authentication. Any thoughts? I can post some of the links of the articles I've already read through if that would help the forum better narrow my needs. Many thanks. tl;dr: How to do mixed mode authentication (forms, windows) in IIS7 without changing to classic pipeline and still be able to use the build in IIS6 if possible.

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  • C# Can I return HttpWebResponse result to iframe - Uses Digest authentication

    - by chadsxe
    I am trying to figure out a way to display a cross-domain web page that uses Digest Authentication. My initial thought was to make a web request and return the entire page source. I currently have no issues with authenticating and getting a response but I am not sure how to properly return the needed data. // Create a request for the URL. WebRequest request = WebRequest.Create("http://some-url/cgi/image.php?type=live"); // Set the credentials. request.Credentials = new NetworkCredential(username, password); // Get the response. HttpWebResponse response = (HttpWebResponse)request.GetResponse(); // Get the stream containing content returned by the server. Stream dataStream = response.GetResponseStream(); // Open the stream using a StreamReader for easy access. StreamReader reader = new StreamReader(dataStream); // Read the content. string responseFromServer = reader.ReadToEnd(); // Clean up the streams and the response. reader.Close(); dataStream.Close(); response.Close(); return responseFromServer; My problems are currently... responseFromServer is not returning the entire source of the page. I.E. missing body and head tags The data is encoded improperly in responseFromServer. I believe this has something to do with the transfer encoding being of the type chunked. Further more... I am not entirely sure if this is even possible. If it matters, this is being done in ASP.NET MVC 4 C#. Thanks, Chad

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  • How to improve WinForms MSChart performance?

    - by Marcel
    Hi all, I have created some simple charts (of type FastLine) with MSChart and update them with live data, like below: . To do so, I bind an observable collection of a custom type to the chart like so: // set chart data source this._Chart.DataSource = value; //is of type ObservableCollection<SpectrumLevels> //define x and y value members for each series this._Chart.Series[0].XValueMember = "Index"; this._Chart.Series[1].XValueMember = "Index"; this._Chart.Series[0].YValueMembers = "Channel0Level"; this._Chart.Series[1].YValueMembers = "Channel1Level"; // bind data to chart this._Chart.DataBind(); //lasts 1.5 seconds for 8000 points per series At each refresh, the dataset completely changes, it is not a scrolling update! With a profiler I have found that the DataBind() call takes about 1.5 seconds. The other calls are negligible. How can I make this faster? Should I use another type than ObservableCollection? An array probably? Should I use another form of data binding? Is there some tweak for the MSChart that I may have missed? Should I use a sparsed set of date, having one value per pixel only? Have I simply reached the performance limit of MSCharts? From the type of the application to keep it "fluent", we should have multiple refreshes per second. Thanks for any hints!

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  • WPF: Adorner Hit Testing / MouseDown Event

    - by stefan.at.wpf
    Hello, I have an Adorner which adornes a Border (please see screenshot below). The MouseDown Event for the Adorner is however only raised, when clicking on an element in the adorner. I need the MouseDown Event to be raised, when clicking on any place in the adorner above the adorned element. How can this be done? Do I have to add an transparent control in the adorner or is there another way for this? Thanks for any help! Screenshot and VS 2008 Project: http://cid-0432ee4cfe9c26a0.skydrive.live.com/browse.aspx/%C3%96ffentlich?uc=2 The Code for the adorner: class myAdorner : Adorner { public myAdorner(UIElement element) : base(element) { this.MouseDown += new System.Windows.Input.MouseButtonEventHandler(myAdorner_MouseDown); } void myAdorner_MouseDown(object sender, System.Windows.Input.MouseButtonEventArgs e) { MessageBox.Show("ok"); } // Draws two rectangles: one in the upper-left and another one in the lower-right corner protected override void OnRender(System.Windows.Media.DrawingContext drawingContext) { Size size = this.AdornedElement.RenderSize; Rect r1 = new Rect(0.5, 0.5, 20, 20); Rect r4 = new Rect(size.Width - 20.5, size.Height - 20.5, 20, 20); SolidColorBrush brush = new SolidColorBrush(Colors.AliceBlue); Pen pen = new Pen(Brushes.Black, 1); drawingContext.DrawRectangle(brush, pen, r1); drawingContext.DrawRectangle(brush, pen, r4); } }

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  • Azure - Unable To Get SQL Azure Invitation Code!

    - by Goober
    Scenario I'm trying to convert my Silverlight Business Application over to the cloud with the help of Azure. I have been following this link from Brad Abrams blog. Both the links to Windows Azure and SQL Azure crash out in Google Chrome, they work in Internet Explorer, but it's literally one of the worst user experiences I've ever had. The Problem I'm asked to sign in to Microsoft connect with my Live ID. I do so, I'm then asked to register!? - I do so. I'm then sent a verification email which I verify. I'm then signed out!?!?! When I sign back in, it repeats the process.... ANY IDEAS!??! Edit/Update: Finally managed to get signed up/in to connect. From here I was able to get hold of an invitation code to Windows Azure. Now I need an invitation code for SQL Azure. I cannot see ANYWHERE that advertises a way of getting this SQL Azure code, the only thing that I have seen is some text saying that there "may be a delay" in receiving codes due to volume of interest, which quite frankly I find hard to believe......... It's so far been 3 days now.This officially Sucks! If I have any more news I'll post back here.

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  • Partial template specialization of free functions - best practices

    - by Poita_
    As most C++ programmers should know, partial template specialization of free functions is disallowed. For example, the following is illegal C++: template <class T, int N> T mul(const T& x) { return x * N; } template <class T> T mul<T, 0>(const T& x) { return T(0); } // error: function template partial specialization ‘mul<T, 0>’ is not allowed However, partial template specialization of classes/structs is allowed, and can be exploited to mimic the functionality of partial template specialization of free functions. For example, the target objective in the last example can be achieved by using: template <class T, int N> struct mul_impl { static T fun(const T& x) { return x * N; } }; template <class T> struct mul_impl<T, 0> { static T fun(const T& x) { return T(0); } }; template <class T, int N> T mul(const T& x) { return mul_impl<T, N>::fun(x); } It's more bulky and less concise, but it gets the job done -- and as far as users of mul are concerned, they get the desired partial specialization. My questions is: when writing templated free functions (that are intended to be used by others), should you automatically delegate the implementation to a static method function of a class, so that users of your library may implement partial specializations at will, or do you just write the templated function the normal way, and live with the fact that people won't be able to specialize them?

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  • jQuery autocomplete - update options on dynamically created elements

    - by Ian Robinson
    Background The user enters values into multiple inputs on the page. Think of entering a list of widgets for sale. The user would select the type of a widget from a drop down. Then enter the name of the Widget vendor, and then the actual name of the widget. These UI elements would all appear as one row. The user is able to click an "add another widget" link and a new row is created. The two input elements have autocomplete functionality attached to them using the DevBridge jQuery plugin. It suggests the name of the vendor and the name of the widget. I have recently wired up the logic to filter the name of the widget based on the name of the vendor you entered. This means setting the (custom) vendorName parameter when attaching the autocomplete plugin so it can be passed to the server side to retrieve the widget names for that vendor that match the name the user entered. To achieve this functionality I'm dynamically attaching the autocomplete functionality to the second element (the widget name text box) when it receives focus. Here is an example: $('.autocomplete-widget').live('focus', function () { $(this).autocomplete({ serviceUrl: '/something.ashx', params: { type: 'widget', vendorName: $(this).parent().prev().find('.autocomplete-vendor').val()} }); }); Problem At first glance, this looks to function quite well. However I started noticing some inconsistencies, and upon inspection, I found out that the call to the server is actually happening several times in some cases. Each time the widget name input element receives focus the autocomplete functionality is attached. And what I'm seeing is that the call to the server is made in proportion to how many times the input element has gained focus. I'd like to avoid making the call more than once, but retain the ability to attach (or update) the autocomplete functionality "on focus". I've tried to use the autocomplete 'setOptions' method but have only been able to get it to work with the static elements, not the dynamically created elements. Question Is there a way I can clear out the autocomplete functionality before I attach another one?

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  • How can I beta test web Perl modules under Apache/mod_perl on production web server?

    - by DVK
    We have a setup where most code, before being promoted to full production, is deployed in BETA mode - meaning, it runs in full production environment (using production database - usually production data; and production web server). We call that stage BETA testing. One of the main requirements is that BETA code promotion to production must be a simple "cp" command from beta to production directory - no code/filename changes. For non-web Perl code, achieving seamless BETA test is quite doable (see details here): Perl programs live in a standard location under production root (/usr/code/scripts) with production perl modules living under the same root (/usr/code/lib/perl) The BETA code has 100% same code paths except under beta root (/usr/code/beta/) A special module manipulates @INC of any script based on whether the script was called from /usr/code/scripts or /usr/code/test/scripts, to include beta libraries for beta scripts. This setup works fine up till we need to beta test our web Perl code (the setup is EmbPerl and Apache/mod_perl). The hang-up is as follows: if both a production Perl module and BETA Perl module have the same name (e.g. /usr/code/lib/perl/MyLib1.pm and /usr/code/beta/lib/perl/MyLib1.pm), then mod_perl will only be able to load ONE of these modules into memory - and there's no way we are aware of for a particular web page to affect which version of the module is currently loaded due to concurrency issues. Leaving aside the obvious non-programming solution (get a bloody BETA web server) which for political/organizational reasons is not feasible, is there any way we can somehow hack around this problem in either Perl or mod_perl? I played around with various approaches to unloading Perl modules that %INC has listed, but the problem remains that another user might load a beta page at just the right (or rather wrong) moment and have the beta module loaded which will be used for my production page.

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  • A simple augmented reality application in C#

    - by Ian
    Hi All, I would like to start a personal project that will give me a lot of new concept to learn and understand. After some thought, I figured that an Augmented Reality related project will be the most beneficial for me because of the following reasons: I haven't tried interfacing a program with a live video/camera feed I haven't done any "image processing" project I haven't done any "graphics rendering" ever With that said, you can assume that I will totally suck at AR. So I'm here to ask for some advice regarding the best way to go through this. st milestone project that I am thinking of is to take a cheap webcam and read some Data Matrix using C#. nd milestone project will render some text-overlay on the feed when presented with a certain Data Matrix. rd milestone project will actually render some 3D shapes. I've searched all-around and found some nice yet advanced materials for AR: http://sites.google.com/site/augmentedrealitytestingsite/ http://soldeveloper.com/ http://www.mperfect.net/wpfAugReal/ So I came here to ask the following: Do you think my milestone is reasonable given my "deficiencies"? In order to start Milestone 1, can you give some materials that I can study? I prefer online materials. Thanks!

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  • Problem with Informix JDBC, MONEY and decimal separator in string literals

    - by Michal Niklas
    I have problem with JDBC application that uses MONEY data type. When I insert into MONEY column: insert into _money_test (amt) values ('123.45') I got exception: Character to numeric conversion error The same SQL works from native Windows application using ODBC driver. I live in Poland and have Polish locale and in my country comma separates decimal part of number, so I tried: insert into _money_test (amt) values ('123,45') And it worked. I checked that in PreparedStatement I must use dot separator: 123.45. And of course I can use: insert into _money_test (amt) values (123.45) But some code is "general", it imports data from csv file and it was safe to put number into string literal. How to force JDBC to use DBMONEY (or simply dot) in literals? My workstation is WinXP. I have ODBC and JDBC Informix client in version 3.50 TC5/JC5. I have set DBMONEY to just dot: DBMONEY=. EDIT: Test code in Jython: import sys import traceback from java.sql import DriverManager from java.lang import Class Class.forName("com.informix.jdbc.IfxDriver") QUERY = "insert into _money_test (amt) values ('123.45')" def test_money(driver, db_url, usr, passwd): try: print("\n\n%s\n--------------" % (driver)) db = DriverManager.getConnection(db_url, usr, passwd) c = db.createStatement() c.execute("delete from _money_test") c.execute(QUERY) rs = c.executeQuery("select amt from _money_test") while (rs.next()): print('[%s]' % (rs.getString(1))) rs.close() c.close() db.close() except: print("there were errors!") s = traceback.format_exc() sys.stderr.write("%s\n" % (s)) print(QUERY) test_money("com.informix.jdbc.IfxDriver", 'jdbc:informix-sqli://169.0.1.225:9088/test:informixserver=ol_225;DB_LOCALE=pl_PL.CP1250;CLIENT_LOCALE=pl_PL.CP1250;charSet=CP1250', 'informix', 'passwd') test_money("sun.jdbc.odbc.JdbcOdbcDriver", 'jdbc:odbc:test', 'informix', 'passwd') Results when I run money literal with dot and comma: C:\db_examples>jython ifx_jdbc_money.py insert into _money_test (amt) values ('123,45') com.informix.jdbc.IfxDriver -------------- [123.45] sun.jdbc.odbc.JdbcOdbcDriver -------------- there were errors! Traceback (most recent call last): File "ifx_jdbc_money.py", line 16, in test_money c.execute(QUERY) SQLException: java.sql.SQLException: [Informix][Informix ODBC Driver][Informix]Character to numeric conversion error C:\db_examples>jython ifx_jdbc_money.py insert into _money_test (amt) values ('123.45') com.informix.jdbc.IfxDriver -------------- there were errors! Traceback (most recent call last): File "ifx_jdbc_money.py", line 16, in test_money c.execute(QUERY) SQLException: java.sql.SQLException: Character to numeric conversion error sun.jdbc.odbc.JdbcOdbcDriver -------------- [123.45]

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  • Delphi Prism and LINQ to SQL / Entity Framework

    - by Vegar
    I have found many posts and examples of using LINQ-syntax in Delphi Prism (Oxygene), but I have never found anything on LINQ to SQL or Entity Framework. Is it possible to use LINQ to SQL or Entity Framework together with Prism? Where can I found such an example? Update: Olaf is giving an answer through his blog The question is now if any visual tools and code generation is provided, or if everything must be done by hand... Second update: Olaf has answered the tool/code generation-question in a comment on his site: The class designer is there, but there is no Pascal code gen. According to marc hoffman that is currently not on their list. For now you have to live with manual mapping. I guess, if you had Visual Studio (not just the VS shell), that you could add a C# library project to your solution, reference that from your Prism project. Then create the Table-Class mapping in the C# project using the visual designer. Maybe somewhat ugly, but possibly the key to get the Designer + CodeGen integrated into Prism. Who cares what language is used for the mapping . I will say this is a 1 - 0 to c# vs prism. If I did not care which language is used for the mapping - why should I care about which language is used for the rest?

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  • UIImagePickerController crashing

    - by Mike
    I am developing a project based on iPhone OS 3.2 This project uses UIImagePickerController to pick videos. I have managed to put a video inside the iPad simulator. Photos.app can see and play the video, that was created using an iPhone 3GS, but whey I try to use the UIImagePickerController, it simply crashes my app. THis is the code I am using: if ([UIImagePickerController isSourceTypeAvailable: UIImagePickerControllerSourceTypePhotoLibrary]) { UIImagePickerController *picker = [[UIImagePickerController alloc] init]; picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary; picker.mediaTypes = [UIImagePickerController availableMediaTypesForSourceType:picker.sourceType];//shows movies and photos on iPhone picker.delegate = self; picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary; UIPopoverController *popover = [[UIPopoverController alloc] initWithContentViewController:picker]; CGRect myRect = CGRectMake(0,0,100,100); // this is a random rect just for testing [popover presentPopoverFromRect:myRect inView:myMainView permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES]; } after running this, the app crashes miserably with the following message Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Popovers cannot be presented from a view which does not have a window.' Is there something wrong with the code or it is just the simulator crashing because it is unable to pick videos? please refrain from recommending me to test on a real device. The problem is that I live outside the US and there's no iPad here soon. thanks.

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  • Hibernate criteria query to match against all child collection elements

    - by Andrew Harrison
    Hi, This question is very similar to link text but the responses were minimal to that question. I have a parent class with a Set of child entities. The child entities are just a wrapper for a string and live in a different table to the parent entity. I want to have a criteria query that returns the parent entities when all the members of the set of child entities return true to a condition. This condition is matching against one of a list of strings. Here's where I am: Criteria c = criteria(); Criteria ands = c.createCriteria("ands"); Disjunction dis = Restrictions.disjunction(); for (String value : values) { dis.add(Restrictions.like("value", "%" + value + "%")); } ands.add(dis); return list(c); "ands" is the set of entities with a "value" field that is a string. "criteria()" creates a criteria for the parent class. "list()" just calls criteria.list(); This is just matching against any of the elements, rather than all. Hope this makes sense. Any help much appreciated.

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  • MySQL 5 multiple JOIN syntax not working in MySQL 4

    - by draco
    Hello all, the current SQL query works fine locally on MAMP 1.8.4 running MySQL 5.1.37. SELECT EL.log_actions, EL.log_date, EL.log_value, EL.log_type, EA.admins_name, EU.users_name, EU.users_matric FROM events_log EL JOIN events_users EU USING (users_id) JOIN events_admins EA USING (admins_id) ORDER BY EL.log_id DESC LIMIT 0, 10 However, when I bring this query live to production server which is running MySQL 4.1.22-standard, the following error occurred (whether or not there are data in the entry). A Database Error Occurred Error Number: 1054 Unknown column 'sceclub_exclaim2007.EU.admins_id' in 'on clause' SELECT EL.log_actions, EL.log_date, EL.log_value, EL.log_type, EA.admins_name, EU.users_name, EU.users_matric FROM events_log EL JOIN events_users EU USING (users_id) JOIN events_admins EA USING (admins_id) ORDER BY EL.log_id DESC LIMIT 0, 20 This is based on CodeIgniter 1.7.2 and both production and development are running the same set of database. Database tables events_users: users_id users_name users_credits users_matric users_redeem events_admins: admins_id admins_email admins_name admins_pass admins_date admins_modified admins_last_login events_attendance: attendance_id users_id events_id events_events: events_id events_name events_venue events_time events_desc events_pass events_log:log_id admins_id log_actions log_date log_value users_id log_type I'm new to MySQL so I'm not aware of any difference in versions or what could be a possible cause, thank you in advance! Tried googling for MySQL4 difference to no avail too. Also tried using SELECT EL.log_actions, EL.log_date, EL.log_value, EL.log_type, EA.admins_name, EU.users_name, EU.users_matric FROM events_log EL JOIN events_users EU where EL.users_id = EU.users_id JOIN events_admins EA USING EL.admins_id = EA.admins_id ORDER BY EL.log_id DESC LIMIT 0, 10 But then I got the error in both production and development. A Database Error Occurred Error Number: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'JOIN events_admins EA USING EL.admins_id = EA.admins_id ORDER BY' at line 8 SELECT EL.log_actions, EL.log_date, EL.log_value, EL.log_type, EA.admins_name, EU.users_name, EU.users_matric FROM events_log EL JOIN events_users EU where EL.users_id = EU.users_id JOIN events_admins EA USING EL.admins_id = EA.admins_id ORDER BY EL.log_id DESC LIMIT 0, 20 If you can point me to some resources where I can read up more on MySQL 4 syntax to achieve the same thing effect like I did with MySQL 5 syntax, please let me know. Thanks again!

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  • java.lang.OutOfMemoryError: bitmap size exceeds VM budget ?

    - by UMMA
    friends, i am using following code to display bitmap on screen and having next and previous buttons to change images. and getting out of memory error New Code HttpGet httpRequest = null; try { httpRequest = new HttpGet(mImage_URL[val]); } catch (Exception e) { return 0; } HttpClient httpclient = new DefaultHttpClient(); HttpResponse response = (HttpResponse) httpclient.execute(httpRequest); Bitmap bm; HttpEntity entity = response.getEntity(); BufferedHttpEntity bufHttpEntity = new BufferedHttpEntity(entity); InputStream is = bufHttpEntity.getContent(); try { bm = BitmapFactory.decodeStream(is); }catch(Exception ex) { } is.close(); Old Code URL aURL = new URL(mImage_URL[val]); URLConnection conn = aURL.openConnection(); conn.connect(); InputStream is = null; try { is= conn.getInputStream(); }catch(IOException e) { } BufferedInputStream bis = new BufferedInputStream(is); bm = BitmapFactory.decodeStream(bis); bis.close(); is.close(); img.setImageBitmap(bm); and it was giving me error decoder-decode return false. on images of size bigger than 400kb. so after googling i got new code as answer the old code was not giving me out of memory error on those images but decoder-decode return false, so i choosed new code. any one guide me what is the solution and which is the best approach to display live images?

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  • Is this an acceptable UI design decision?

    - by DVK
    OK, while I'm on record as stating that StackExchange UI is pretty much one of the best websites and overall GUIs that I have ever seen as far as usability goes, there's one particular aspect of the trilogy that bugs me. For an example, head on to http://meta.stackoverflow.com . Look at the banner on top (the one that says "reminder -- it's April Fool's Day depending on your time zone!"). Personally, I feel that this is a "make the user do the figuring out work" anti-pattern (whatever it's officially called) - namely, instead of making your app smart enough to only present a certain mode of operations in the conditions when that mode is appropriate, you simply turn on the mode full on and put an explanation to the user of why the mode is on when it should not be (in this particular example, the mode is of course displaying the unicorn gravatars starting with 00:00 in the first timezone, despite the fact that some users still live in March 31st). The Great Recalc was also handled the same way - instead of proactively telling the user "your rep was changed from X to Y" the same nearly invisible banner was displayed on meta. So, the questions are: Is there such an official anti-pattern, and if so,m what the heck do i call it? Do you have any other well-known examples of such design anti-pattern? How would you fix either the SO example I made or you your own example? Is there a pattern of fixing or must it be a case-by-case solution?

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  • Reloading an external element (via jQuery's .load) without impact on same-named host elements on sam

    - by Martin Pescador
    Hello together! [First, I'm an absolute beginner. I tried to express myself as good as I could - please correct me on any issue... Now: I have the following problem:] I am loading a div element, which class always is ".gallery" from a couple of pages (in this example "the page index.php?page=orange") into another page's div (in this case with the ID "orange") using the following code: $("#orange").load("http://example.com/index.php?page=orange .gallery"); Each div.gallery I load in, is a set of a few images. Between them, you can switch (there are "previous"- and "next"-links in ".imgnavi"). $(".imgnavi a").live("click", function(ev) { ev.preventDefault(); ev.stopPropagation(); $(".gallery").load($(this).attr("href")); return false; }) What happens now: Loading the different div.gallery into the new page is no problem, but as soon as I start to navigate inside those divs (each div is a little gallery, where you can switch between images), the div.gallery I am switching in is suddenly loaded into EVERY other div.gallery in the document! How do I prevent that?

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