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• "EXC_BAD_ACCESS: Unable to restore previously selected frame" Error, Array size?

  - by Job

  Hi there, I have an algorithm for creating the sieve of Eratosthenes and pulling primes from it. It lets you enter a max value for the sieve and the algorithm gives you the primes below that value and stores these in a c-style array. Problem: Everything works fine with values up to 500.000, however when I enter a large value -while running- it gives me the following error message in xcode: Program received signal: “EXC_BAD_ACCESS”. warning: Unable to restore previously selected frame. Data Formatters temporarily unavailable, will re-try after a 'continue'. (Not safe to call dlopen at this time.) My first idea was that I didn't use large enough variables, but as I am using 'unsigned long long int', this should not be the problem. Also the debugger points me to a point in my code where a point in the array get assigned a value. Therefore I wonder is there a maximum limit to an array? If yes: should I use NSArray instead? If no, then what is causing this error based on this information? EDIT: This is what the code looks like (it's not complete, for it fails at the last line posted). I'm using garbage collection. /*--------------------------SET UP--------------------------*/ unsigned long long int upperLimit = 550000; // unsigned long long int sieve[upperLimit]; unsigned long long int primes[upperLimit]; unsigned long long int indexCEX; unsigned long long int primesCounter = 0; // Fill sieve with 2 to upperLimit for(unsigned long long int indexA = 0; indexA < upperLimit-1; ++indexA) { sieve[indexA] = indexA+2; } unsigned long long int prime = 2; /*-------------------------CHECK & FIND----------------------------*/ while(!((prime*prime) > upperLimit)) { //check off all multiples of prime for(unsigned long long int indexB = prime-2; indexB < upperLimit-1; ++indexB) { // Multiple of prime = 0 if(sieve[indexB] != 0) { if(sieve[indexB] % prime == 0) { sieve[indexB] = 0; } } } /*---------------- Search for next prime ---------------*/ // index of current prime + 1 unsigned long long int indexC = prime - 1; while(sieve[indexC] == 0) { ++indexC; } prime = sieve[indexC]; // Store prime in primes[] primes[primesCounter] = prime; // This is where the code fails if upperLimit > 500000 ++primesCounter; indexCEX = indexC + 1; } As you may or may not see, is that I am -very much- a beginner. Any other suggestions are welcome of course :)

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• Is this slow WPF TextBlock performance expected?

  - by Ben Schoepke

  Hi, I am doing some benchmarking to determine if I can use WPF for a new product. However, early performance results are disappointing. I made a quick app that uses data binding to display a bunch of random text inside of a list box every 100 ms and it was eating up ~15% CPU. So I made another quick app that skipped the data binding/data template scheme and does nothing but update 10 TextBlocks that are inside of a ListBox every 100 ms (the actual product wouldn't require 100 ms updates, more like 500 ms max, but this is a stress test). I'm still seeing ~10-15% CPU usage. Why is this so high? Is it because of all the garbage strings? Here's the XAML: <Grid> <ListBox x:Name="numericsListBox"> <ListBox.Resources> <Style TargetType="TextBlock"> <Setter Property="FontSize" Value="48"/> <Setter Property="Width" Value="300"/> </Style> </ListBox.Resources> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> <TextBlock/> </ListBox> </Grid> Here's the code behind: public partial class Window1 : Window { private int _count = 0; public Window1() { InitializeComponent(); } private void OnLoad(object sender, RoutedEventArgs e) { var t = new DispatcherTimer(TimeSpan.FromSeconds(0.1), DispatcherPriority.Normal, UpdateNumerics, Dispatcher); t.Start(); } private void UpdateNumerics(object sender, EventArgs e) { ++_count; foreach (object textBlock in numericsListBox.Items) { var t = textBlock as TextBlock; if (t != null) t.Text = _count.ToString(); } } } Any ideas for a better way to quickly render text? My computer: XP SP3, 2.26 GHz Core 2 Duo, 4 GB RAM, Intel 4500 HD integrated graphics. And that is an order of magnitude beefier than the hardware I'd need to develop for in the real product.

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• How to make Flash 'play well with others'?

  - by Sensei James

  What up fam. So this isn't a question asking about memory management schemes; for those of you who may not know, the Flash Virtual Machine relies on garbage collection by using reference counting and mark and sweep (for good coverage of these topics, check out Grant Skinner's article and presentation). And yes, Flash also provides the "delete" operator, which can (unfortunately only) be used to remove the properties of dynamic objects. What I want to know is how to make it so that Flash programs don't continue to consume CPU and memory while running in the background (save loading content or communicating remotely, for example). The motivation for this question comes in part from Apple's ban on cross compiled applications (in its SDK 4) on the grounds that they do not behave as predicted with the multitasking feature central to iPhone OS 4. My intention is not only to make Flash programs that will 'pass muster' as far as multitasking in iPhone OS 4, but also to simply make better (behaving) Flash programs. Put another way, how might a Flash application mimic the multitasking feature of iPhone OS 4? Does the Flash API provide the means for a developer to put their applications to 'sleep' while other programs run, and then to 'awaken' them just as quickly? In our own program, we might do something as crude as detecting when the user has been idle (no mouse motion or key press) for (say) four seconds: var idle_id:uint = setInterval(4000, pause_program); var current_movie_clip:MovieClip; var current_frame:uint; ... // on Mouse move or key press... clearInterval(idle_id); idle_id = setInterval(4000, pause_program); ... function pause_program():void { current_movie_clip = event.target as MovieClip; current_frame = current_movie_clip.currentFrame; MovieClip(root).gotoAndStop("program_pause_screen"); } (on the program pause screen) resume_button.addEventListener(MouseEvent.CLICK, resume_program); function resume_program(event:MouseEvent) { current_movie_clip.gotoAndPlay(current_frame); } If that's the right idea, what's the best way to detect that an application should be shelved? And, more importantly, is it possible for Flash Player to detect that some of its running programs are idle, and to similarly shelve them until the user performs an action to resume them? (Please feel free to answer as much or as little of the many questions I've posed.)

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• iPhone: value of selectedIndex for tab should be consistent, but isn't

  - by Janine

  This should be so simple... but something screwy is happening. My setup looks like this: MainViewController Tab Bar Controller 4 tabs, each of which loads WebViewController My AppDelegate contains an ivar, tabBarController, which is connected to the tab bar controller (this was all set up in Interface Builder). The leftmost tab is marked "selected" in IB. Within the viewWillAppear method in WebViewController, I need to know which tab was just selected so I can load the correct URL. I do this by switching on appDelegate.tabBarController.selectedIndex. When the app first runs and the leftmost tab is selected, selectedIndex is a large garbage value. After that, I get values from 0 to 3, which is as it should be, but they are in random order. Not only that, but each tab I touch reports a different value each time. This app is extremely simple right now and I can't imagine what I could have done to make things go this wrong. Has anyone seen (and hopefully solved) this behavior? Update: we have a request for code. There's not much to see. The tab bar controller gets loaded in applicationDidFinishLaunching: [self.mainViewController view]; //force nib to load [self.window addSubview:self.mainViewController.tabBarController.view] There is currently no code whatsoever in MainViewController.m other than the synthesize and release for tabBarController. From WebVewController.m: - (void)viewWillAppear:(BOOL)_animation { [super viewWillAppear:_animation]; NSURL *url; switch([S_UIDelegate mainViewController].tabBarController.selectedIndex) { case 0: url = [NSURL URLWithString:@"http://www.cnn.com"]; break; case 1: url = [NSURL URLWithString:@"http://www.facebook.com"]; break; case 2: url = [NSURL URLWithString:@"http://www.twitter.com"]; break; case 3: url = [NSURL URLWithString:@"http://www.google.com"]; break; default: url = [NSURL URLWithString:@"http://www.msnbc.com"]; } NSURLRequest *request = [NSURLRequest requestWithURL:url]; [webView loadRequest:request]; } This is where I'm seeing the random values.

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• Reliable and fast way to convert a zillion ODT files in PDF?

  - by Marco Mariani

  I need to pre-produce a million or two PDF files from a simple template (a few pages and tables) with embedded fonts. Usually, I would stay low level in a case like this, and compose everything with a library like ReportLab, but I joined late in the project. Currently, I have a template.odt and use markers in the content.xml files to fill with data from a DB. I can smoothly create the ODT files, they always look rigth. For the ODT to PDF conversion, I'm using openoffice in server mode (and PyODConverter w/ named pipe), but it's not very reliable: in a batch of documents, there is eventually a point after which all the processed files are converted into garbage (wrong fonts and letters sprawled all over the page). Problem is not predictably reproducible (does not depend on the data), happens in OOo 2.3 and 3.2, in Ubuntu, XP, Server 2003 and Windows 7. My Heisenbug detector is ticking. I tried to reduce the size of batches and restarting OOo after each one; still, a small percentage of the documents are messed up. Of course I'll write about this on the Ooo mailing lists, but in the meanwhile, I have a delivery and lost too much time already. Where do I go? Completely avoid the ODT format and go for another template system. Suggestions? Anything that takes a few seconds to run is way too slow. OOo takes around a second and it sums to 15 days of processing time. I had to write a program for clustering the jobs over several clients. Keep the format but go for another tool/program for the conversion. Which one? There are many apps in the shareware or commercial repositories for windows, but trying each one is a daunting task. Some are too slow, some cannot be run in batch without buying it first, some cannot work from command line, etc. Open source tools tend not to reinvent the wheel and often depend on openoffice. Converting to an intermediate .DOC format could help to avoid the OOo bug, but it would double the processing time and complicate a task that is already too hairy. Try to produce the PDFs twice and compare them, discarding the whole batch if there's something wrong. Although the documents look equal, I know of no way to compare the binary content. Restart OOo after processing each document. it would take a lot more time to produce them it would lower the percentage of the wrong files, and make it very hard to identify them. Go for ReportLab and recreate the pages programmatically. This is the approach I'm going to try in a few minutes. Learn to properly format bulleted lists Thanks a lot.

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• Is it possible to reliably auto-decode user files to Unicode? [C#]

  - by NVRAM

  I have a web application that allows users to upload their content for processing. The processing engine expects UTF8 (and I'm composing XML from multiple users' files), so I need to ensure that I can properly decode the uploaded files. Since I'd be surprised if any of my users knew their files even were encoded, I have very little hope they'd be able to correctly specify the encoding (decoder) to use. And so, my application is left with task of detecting before decoding. This seems like such a universal problem, I'm surprised not to find either a framework capability or general recipe for the solution. Can it be I'm not searching with meaningful search terms? I've implemented BOM-aware detection (http://en.wikipedia.org/wiki/Byte_order_mark) but I'm not sure how often files will be uploaded w/o a BOM to indicate encoding, and this isn't useful for most non-UTF files. My questions boil down to: Is BOM-aware detection sufficient for the vast majority of files? In the case where BOM-detection fails, is it possible to try different decoders and determine if they are "valid"? (My attempts indicate the answer is "no.") Under what circumstances will a "valid" file fail with the C# encoder/decoder framework? Is there a repository anywhere that has a multitude of files with various encodings to use for testing? While I'm specifically asking about C#/.NET, I'd like to know the answer for Java, Python and other languages for the next time I have to do this. So far I've found: A "valid" UTF-16 file with Ctrl-S characters has caused encoding to UTF-8 to throw an exception (Illegal character?) (That was an XML encoding exception.) Decoding a valid UTF-16 file with UTF-8 succeeds but gives text with null characters. Huh? Currently, I only expect UTF-8, UTF-16 and probably ISO-8859-1 files, but I want the solution to be extensible if possible. My existing set of input files isn't nearly broad enough to uncover all the problems that will occur with live files. Although the files I'm trying to decode are "text" I think they are often created w/methods that leave garbage characters in the files. Hence "valid" files may not be "pure". Oh joy. Thanks.

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• How can I tell groovy/grails not to try to "re-encode" binary data? (Revised title)

  - by ?????

  I have a groovy/grails application that needs to serve images It works fine on my dev box, the image is returned properly. Here's the start of the returned JPEG, as seen by od -cx 0000000 377 330 377 340 \0 020 J F I F \0 001 001 001 001 , d8ff e0ff 1000 464a 4649 0100 0101 2c01 but on the production box, there's some garbage in front, and the d8ff e0ff before the 1000 is missing 0000000 ? ** ** ? ** ** ? ** ** ? ** ** \0 020 J F bfef efbd bdbf bfef efbd bdbf 1000 464a 0000020 I F \0 001 001 001 \0 H \0 H \0 \0 ? ** ** ? 4649 0100 0101 4800 4800 0000 bfef efbd It's the exact same code. I just moved the .war over and run it on a different machine. (Isn't Java supposed to be write once, run everywhere?) Any ideas? An "encoding" problem? The code is sent to the response like this: response.contentType = "image/jpeg"; response.outputStream << out; Here's the code that locates the image on an internal application server and re-serves the image. I've pared down the code a bit to remove the error handling, etc, to make it easier to read. def show = { def address = "http://internal.application.server:9899/img?photoid=${params.id}" def out = new ByteArrayOutputStream() out << new URL(address).openStream() response.contentLength = out.size(); // XXX If you don't do this hack, "head" requests won't work! if (request.method == 'HEAD') { render( text : "", contentType : "image/jpeg" ); } else { response.contentType = "image/jpeg"; response.outputStream << out; } } Update: I tried setting the CharacterEncoding response.setCharacterEncoding("ISO-8859-1"); if (request.method == 'HEAD') { render( text : "", contentType : "image/jpeg" ); } else { response.contentType = "image/jpeg;charset=ISO-8859-1"; response.outputStream << out; } but it made no difference in the output. On my production machine, the binary bytes in the image are re-encoded/escaped as if they were UTF-8 (see Michael's explanation below). It works fine on my development machine.

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• Wondering about a way to conserve memory in C# using List<> with structs

  - by Michael Ryan

  I'm not even sure how I should phrase this question. I'm passing some CustomStruct objects as parameters to a class method, and storing them in a List. What I'm wondering is if it's possible and more efficient to add multiple references to a particular instance of a CustomStruct if a equivalent instance it found. This is a dummy/example struct: public struct CustomStruct { readonly int _x; readonly int _y; readonly int _w; readonly int _h; readonly Enum _e; } Using the below method, you can pass one, two, or three CustomStruct objects as parameters. In the final method (that takes three parameters), it may be the case that the 3rd and possibly the 2nd will have the same value as the first. List<CustomStruct> _list; public void AddBackground(CustomStruct normal) { AddBackground(normal, normal, normal); } public void AddBackground(CustomStruct normal, CustomStruct hover) { AddBackground(normal, hover, hover); } public void AddBackground(CustomStruct normal, CustomStruct hover, CustomStruct active) { _list = new List<CustomStruct>(3); _list.Add(normal); _list.Add(hover); _list.Add(active); } As the method stands now, I believe it will create new instances of CustomStruct objects, and then adds a reference of each to the List. It is my understanding that if I instead check for equality between normal and hover and (if equal) insert normal again in place of hover, when the method completes, hover will lose all references and eventually be garbage collected, whereas normal will have two references in the List. The same could be done for active. That would be better, right? The CustomStruct is a ValueType, and therefore one instance would remain on the Stack, and the three List references would just point to it. The overall List size is determined not by the object Type is contains, but by its Capacity. By eliminating the "duplicate" CustomStuct objects, you allow them to be cleaned up. When the CustomStruct objects are passed to these methods, new instances are created each time. When the structs are added to the List, is another copy made? For example, if i pass just one CustomStruct, AddBackground(normal) creates a copy of the original variable, and then passes it three times to Addbackground(normal, hover, active). In this method, three copies are made of the original copy. When the three local variables are added to the List using Add(), are additional copies created inside Add(), and does that defeat the purpose of any equality checks as previously mentioned? Am I missing anything here?

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• Need a fast programming language that can drive two printers

  - by Pete

  I have a rather unusual application that isn't working the way I need, and I hope someone here will have some suggestions or at least a direction to investigate. We have a museum exhibit that has a computer at the entrance driving two small receipt printers. There are two buttons on a console, wired to the left and right buttons of a disemboweled mouse. The two printers and associated buttons are for girls and boys, each button does a random selection from a database of names and prints a small ticket on the appropriate printer with a graphic image, a few words about the exhibit and the randomly chosen name. Conceptually all is well, but it hangs quite often. I got the project at the last minute, because the original designer got bogged down and couldn't deliver, so the exhibit's author asked me the day before opening, whether I could write something that would work. I did it in Word, since I am an experienced VBA programmer. Several other avenues I attempted first all lead to dead ends - one couldn't do graphics, another couldn't handle two printers, yet another couldn't change fonts and so on. The problem is that it simply isn't fast enough - Word can only drive one printer at a time and changing the active printer takes a long time. Not by office standards, where a second or two of delay before a printer starts working on your document is not an issue, but here I need more or less instant response. If kids press a button and nothing happens, they press it over and over until something does happen, resulting in maybe half a dozen commands being sent before the printer starts reacting. Sometimes it jams the program completely, since boys and girls will be pressing the two buttons simultaneously and Word locks up, and even when it doesn't jam, the printers then spit out a stream of tickets, making a mess. The kids start squabbling over which ticket is whose, pulling them out of the printers, snarling the paper tape, jamming the printer and generally making a mess of the whole affair, often necessitating the exhibit caretakers having to restart the computer and clear torn bits of paper out the printers. What I need is some sort of fast programming language that can drive two printers *-simultaneously-*, not the MSOffice claptrap of having to switch the active printer, that can react to both left and right mouse button click events, can print a small graphic image and can print in different font sizes and styles and. I don't need many, but it's not all in one typeface. Can anyone suggest what I might use for this? I don't even know if it's possible at all under Windows, whether the "single active printer" garbage is an Office artifact, or a Windows restriction. My little Commodore-64 twenty-five years ago had two printers attached to it and drove both simultaneously with no difficulties - it doesn't seem to me it should be such an impossible requirement today.

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• Blending pixels from Two Bitmaps

  - by MarkPowell

  I'm beating my head against a wall here, and I'm fairly certain I'm doing something stupid, so time to make my stupidity public. I'm trying to take two images, blend them together into a third image using standard blending algorithms (Hardlight, softlight, overlay, multiply, etc). Because Android does not have such blend properties build in, I've gone down the path of taking each pixel and combine them using an algorithm. However, the results are garbage. Any help would be appreciated. Below is the code, which I've tried to strip out all the "junk", but some may have made it through. I'll clean it up if something isn't clear. Bitmap src = BitmapFactory.decodeResource(getResources(), R.drawable.base, options); Bitmap mutableBitmap = src.copy(Bitmap.Config.RGB_565, true); int imageId = getResources().getIdentifier("drawable/" + filter, null, getPackageName()); Bitmap filterBitmap = BitmapFactory.decodeResource(getResources(), imageId, options); float scaleWidth = ((float) mutableBitmap.getWidth()) / filterBitmap.getWidth(); float scaleHeight = ((float) mutableBitmap.getHeight()) / filterBitmap.getHeight(); IntBuffer buffSrc = IntBuffer.allocate(src.getWidth() * src.getHeight()); mutableBitmap.copyPixelsToBuffer(buffSrc); buffSrc.rewind(); IntBuffer buffFilter = IntBuffer.allocate(resizedFilterBitmap.getWidth() * resizedFilterBitmap.getHeight()); resizedFilterBitmap.copyPixelsToBuffer(buffFilter); buffFilter.rewind(); IntBuffer buffOut = IntBuffer.allocate(src.getWidth() * src.getHeight()); buffOut.rewind(); while (buffOut.position() < buffOut.limit()) { int filterInt = buffFilter.get(); int srcInt = buffSrc.get(); int alphaValueFilter = Color.alpha(filterInt); int redValueFilter = Color.red(filterInt); int greenValueFilter = Color.green(filterInt); int blueValueFilter = Color.blue(filterInt); int alphaValueSrc = Color.alpha(srcInt); int redValueSrc = Color.red(srcInt); int greenValueSrc = Color.green(srcInt); int blueValueSrc = Color.blue(srcInt); int alphaValueFinal = convert(alphaValueFilter, alphaValueSrc); int redValueFinal = convert(redValueFilter, redValueSrc); int greenValueFinal = convert(greenValueFilter, greenValueSrc); int blueValueFinal = convert(blueValueFilter, blueValueSrc); int pixel = Color.argb(alphaValueFinal, redValueFinal, greenValueFinal, blueValueFinal); buffOut.put(pixel); } buffOut.rewind(); mutableBitmap.copyPixelsFromBuffer(buffOut); BitmapDrawable drawable = new BitmapDrawable(getResources(), mutableBitmap); imageView.setImageDrawable(drawable); } int convert (int in1, int in2) { //simple multiply for example return in1 * in2 / 255; }

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• Across process marhalling problem with an array of points

  - by ElMagn

  Hi All, We have what we think is a marshalling problem with a renderer object when called across process boundaries. The renderer is an ATL COM server with a COM object that implements the IPoints interface defined below: typedef [uuid(B0E01719-005A-427c-B9DD-B42A18E969AE)] struct Point { double X; double Y; } Point; [ object, uuid(3BFECFE3-B4FB-4f14-8257-6E065D02E3B3), helpstring("IPoints Interface"), dual, ] interface IPoints : IDispatch { HRESULT DrawPolyLine([in] long hDC, [in] short count, [in, size_is(count)] Point * points ); // many more like DrawLine } The count parameter represents the number of points and the points parameter represents an array of the actual points. We have two process running, a graphical display process (GDP) and a tabular (grid) display process (TDP). A factory in the GDP, written in C#, creates the renderer and the clients of the renderer in the GDP. When the clients call into the renderer, everything displays correctly. The renderer is created at start up BTW. There is another factory in the TDP, written in VB6, that calls into the factory in the GDP to create the clients. When the clients call into the renderer, only the first point in the array is marshaled correctly, all the other points are garbage. Seems that the rendering works only when the client creation is started from the same process as the renderer. Now, i am not sure what the solution to this problem is. It seems that if we can guarantee that the clients are always created from a thread in the same GDP process as the renderer then the points are marshaled correctly. We tried using a background thread from the Thread Pool in C# and it indeed worked. The problem is that Windows Forms created from the clients stopped working because accessing the form's controls from a thread other than the thread that created the control is not allowed. We might change the calls to access the forms but we have quite a few of them and are trying to look into a different solution that might involve making changes to the renderer. The other problem is that the renderer is legacy code and we can't just change the interface. I am wondering what can we do to the renderer's interface that would help with marshalling from across process calls. Any ideas would be greatly appreciated. Regards, ElMagn

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• Persistent (purely functional) Red-Black trees on disk performance

  - by Waneck

  I'm studying the best data structures to implement a simple open-source object temporal database, and currently I'm very fond of using Persistent Red-Black trees to do it. My main reasons for using persistent data structures is first of all to minimize the use of locks, so the database can be as parallel as possible. Also it will be easier to implement ACID transactions and even being able to abstract the database to work in parallel on a cluster of some kind. The great thing of this approach is that it makes possible implementing temporal databases almost for free. And this is something quite nice to have, specially for web and for data analysis (e.g. trends). All of this is very cool, but I'm a little suspicious about the overall performance of using a persistent data structure on disk. Even though there are some very fast disks available today, and all writes can be done asynchronously, so a response is always immediate, I don't want to build all application under a false premise, only to realize it isn't really a good way to do it. Here's my line of thought: - Since all writes are done asynchronously, and using a persistent data structure will enable not to invalidate the previous - and currently valid - structure, the write time isn't really a bottleneck. - There are some literature on structures like this that are exactly for disk usage. But it seems to me that these techniques will add more read overhead to achieve faster writes. But I think that exactly the opposite is preferable. Also many of these techniques really do end up with a multi-versioned trees, but they aren't strictly immutable, which is something very crucial to justify the persistent overhead. - I know there still will have to be some kind of locking when appending values to the database, and I also know there should be a good garbage collecting logic if not all versions are to be maintained (otherwise the file size will surely rise dramatically). Also a delta compression system could be thought about. - Of all search trees structures, I really think Red-Blacks are the most close to what I need, since they offer the least number of rotations. But there are some possible pitfalls along the way: - Asynchronous writes -could- affect applications that need the data in real time. But I don't think that is the case with web applications, most of the time. Also when real-time data is needed, another solutions could be devised, like a check-in/check-out system of specific data that will need to be worked on a more real-time manner. - Also they could lead to some commit conflicts, though I fail to think of a good example of when it could happen. Also commit conflicts can occur in normal RDBMS, if two threads are working with the same data, right? - The overhead of having an immutable interface like this will grow exponentially and everything is doomed to fail soon, so this all is a bad idea. Any thoughts? Thanks! edit: There seems to be a misunderstanding of what a persistent data structure is: http://en.wikipedia.org/wiki/Persistent_data_structure

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• Problem with pointers and getstring function

  - by volting

  I am trying to write a function to get a string from the uart1. Its for an embedded system so I don't want to use malloc. The pointer that is passed to the getstring function seems to point to garbage after the gets_e_uart1() is called. I don't use pointers too often so I'm sure it is something really stupid and trivial that Im doing wrong. Regards, V int main() { char *ptr = 0; while(1) { gets_e_uart1(ptr, 100); puts_uart1(ptr); } return 0; }*end main*/ //------------------------------------------------------------------------- //gets a string and echos it //returns 0 if there is no error char getstring_e_uart1(char *stringPtr_, const int SIZE_) { char buffer_[SIZE_]; stringPtr_ = buffer_; int start_ = 0, end_ = SIZE_ - 1; char errorflag = 0; /*keep geting chars until newline char recieved*/ while((buffer_[start_++] = getchar_uart1())!= 0x0D) { putchar_uart1(buffer_[start_]);//echo it /*check for end of buffer wraparound if neccesary*/ if(start_ == end_) { start_ = 0; errorflag = 1; } } putchar_uart1('\n'); putchar_uart1('\r'); /*check for end of buffer wraparound if neccesary*/ if(start_ == end_) { buffer_[0] = '\0'; errorflag = 1; } else { buffer_[start_++] = '\0'; } return errorflag; } Update: I decided to go with approach of passing a pointer an array to the function. This works nicely, thanks to everyone for the informative answers. Updated Code: //------------------------------------------------------------------------- //argument 1 should be a pointer to an array, //and the second argument should be the size of the array //gets a string and echos it //returns 0 if there is no error char getstring_e_uart1(char *stringPtr_, const int SIZE_) { char *startPtr_ = stringPtr_; char *endPtr_ = startPtr_ + (SIZE_ - 1); char errorflag = 0; /*keep geting chars until newline char recieved*/ while((*stringPtr_ = getchar_uart1())!= 0x0D) { putchar_uart1(*stringPtr_);//echo it stringPtr_++; /*check for end of buffer wraparound if neccesary*/ if(stringPtr_ == endPtr_) { stringPtr_ = startPtr_; errorflag = 1; } } putchar_uart1('\n'); putchar_uart1('\r'); /*check for end of buffer wraparound if neccesary*/ if(stringPtr_ == endPtr_) { stringPtr_ = startPtr_; *stringPtr_ = '\0'; errorflag = 1; } else { *stringPtr_ = '\0'; } return errorflag; }

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• IContextMenu::GetCommandString Not showing help text in Windows Explorer

  - by Grant

  Hi, i am implementing a shell context menu for windows explorer and have successfully created the menu's. What i am having trouble with is the IContextMenu::GetCommandString method that displays the help text in the status bar when you hover over the selected menu item. When i do hover over each item nothing is displayed, but whats weird is that some of the other items that i didnt create, eg - open, or print have had their help text turned into garbage.. Here is a code sample of IContextMenu::QueryContextMenu & IContextMenu::GetCommandString.. int ShellExtLib.IContextMenu.QueryContextMenu(IntPtr hMenu, uint indexMenu, uint idCmdFirst, uint idCmdLast, uint uFlags) { uint idCmd = idCmdFirst; StringBuilder sb = new StringBuilder(1024); try { if ((uFlags & 0xf) == 0 || (uFlags & (uint)ShellExtLib.CMF.CMF_EXPLORE) != 0) { uint selectedFileCount = Helpers.DragQueryFile(m_hDrop, 0xffffffff, null, 0); if (selectedFileCount == 1) { Helpers.DragQueryFile(m_hDrop, 0, sb, sb.Capacity + 1); Documents.Add(sb.ToString()); } else { // MULTIPLE FILES SELECTED. for (uint i = 0; i < selectedFileCount; i++) { Helpers.DragQueryFile(m_hDrop, i, sb, sb.Capacity + 1); Documents.Add(sb.ToString()); } } Helpers.InsertMenu(hMenu, indexMenu++, ShellExtLib.UFLAGS.MF_SEPARATOR | ShellExtLib.UFLAGS.MF_BYPOSITION, 0, null); IntPtr hSubMenu = Helpers.CreateMenu(); if (hSubMenu != IntPtr.Zero) { Helpers.InsertMenu(hSubMenu, 0, ShellExtLib.UFLAGS.MF_STRING | ShellExtLib.UFLAGS.MF_BYPOSITION, idCmd++, "Item 1"); Helpers.InsertMenu(hSubMenu, 1, ShellExtLib.UFLAGS.MF_STRING | ShellExtLib.UFLAGS.MF_BYPOSITION, idCmd++, "Item 2"); Helpers.InsertMenu(hSubMenu, 2, ShellExtLib.UFLAGS.MF_SEPARATOR | ShellExtLib.UFLAGS.MF_BYPOSITION, idCmd++, null); Helpers.InsertMenu(hSubMenu, 3, ShellExtLib.UFLAGS.MF_STRING | ShellExtLib.UFLAGS.MF_BYPOSITION, idCmd++, "Item 3"); Helpers.InsertMenu(hSubMenu, 4, ShellExtLib.UFLAGS.MF_SEPARATOR | ShellExtLib.UFLAGS.MF_BYPOSITION, idCmd++, null); Helpers.InsertMenu(hSubMenu, 5, ShellExtLib.UFLAGS.MF_STRING | ShellExtLib.UFLAGS.MF_BYPOSITION, idCmd++, "Item 4"); Helpers.InsertMenu(hSubMenu, 6, ShellExtLib.UFLAGS.MF_STRING | ShellExtLib.UFLAGS.MF_BYPOSITION, idCmd++, "Item 5"); } Helpers.InsertMenu(hMenu, indexMenu++, ShellExtLib.UFLAGS.MF_STRING | ShellExtLib.UFLAGS.MF_BYPOSITION | ShellExtLib.UFLAGS.MF_POPUP, (uint)hSubMenu, "Main Menu"); Helpers.InsertMenu(hMenu, indexMenu++, ShellExtLib.UFLAGS.MF_SEPARATOR | ShellExtLib.UFLAGS.MF_BYPOSITION, 0, null); return (int)(idCmd - idCmdFirst); } } catch { } return 0; } void ShellExtLib.IContextMenu.GetCommandString(int idCmd, uint uFlags, int pwReserved, StringBuilder commandString, int cchMax) { switch (uFlags) { case (uint)ShellExtLib.GCS.VERB: commandString = new StringBuilder("x"); break; case (uint)ShellExtLib.GCS.HELPTEXTA: commandString = new StringBuilder("y"); break; } } Does anyone have any suggestions? I have read a number of articles on how to build shell extensions and have also been reading MSDN as well.. Thanks.

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• Web Services, Memory Leaks and CRM

  - by Neil

  Hi, I have a website that allows users to upload a csv file. This calls a service that reads the information from the csv, puts it into DynamicEntity objects and calls the CRM service to Create/Update entities in CRM. When this service creates/updates an entity this kicks off other plugins to apply certain business rules. These rules can also Create or Update entites in CRM. The issue here is that the handle count of the w3wp.exe process that the website is calling increases every time the an entity is created or updated and it never comes back down. I tried putting Garbage Collection code in the business rules and this reduces the handle count of the CRM w3wp process (run by the Network Service), but not the other w3wp process. Should I have Dispose methods on the Web Service that calls the CRM service? I hope that makes sense. I'm not overly familiar with memory management issues so any help is appreciated. Can anybody give me some tips on how to stop this from occurring? Thanks, Neil -- EDIT Okay well the handle count goes up when I call the Service.Create(DynamicEntity) method. I don't think placing any code here would be beneficial. When I exit the method/class/service that contains this call the handle count stays as it is. What I need to know is whether this is something I should be managing or is it something CRM takes care of (or doesn't take care of but I can't do anything about it) -- Another Edit Right this is how it works. 1) We have CRM and its related services 2) We have another service independent of CRM that uses the CRM services (number 1 above) to create entities based on csv info passed into it 3) We have a website that allows a user to upload a csv, and calls service no 2 above to Create/Update entities in CRM 4) We have plugins fired by CRM which use Service 1 above to create/update entities So the user uploads a csv to the website (3), this fires a service(2). When service 2 creates an entity using service 1, Service 4 fires. Service 4 calls also uses service 1 to Create entities, and when these services are called (using the Service.Create() method) the handle count of the process increases. When the method/class/services finish the handle count remains the same, and so when the whole process occurs again the handle count will increased again.

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• Structures not working correctly?

  - by booby

  Fraction AddFractions(const Fraction& frac1, const Fraction& frac2) { Fraction frac3; if (frac1.denom == frac2.denom) { frac3.num = frac1.num + frac2.num; frac3.denom = frac1.denom; } else { frac3.denom = (frac1.denom * frac2.denom); frac3.num = (frac1.num * frac2.denom) + (frac2.num * frac1.denom); } return frac3; } This is my prototype and there is a structure defined as Fraction with int num and int denom when I call the function it just gives me back garbage? I don't know what's wrong with it. Please help. =( cout << "Please enter two Fractions" << endl; cout << endl; GetFraction(frac1); cout << "Your fisrt fraction is: "; PrintFraction(frac1); cout << endl; cout << endl; GetFraction(frac2); cout << "Your second fraction is: "; PrintFraction(frac2); cout << endl; do { choice1 = MathMenu(); if (choice1 == ErrorOpt) { cout << "There was an error with what you have entered" << endl; } else if(choice1 != QuitOpt) { // do the math options switch (choice1) { case AddOpt: AddFractions(frac1, frac2); break; case SubtractOpt: SubtractFractions(frac1, frac2); break; case MultiplyOpt: MultiplyFractions(frac1, frac2); break; case DivideOpt: DivideFractions(frac1, frac2); break; } //print the results PrintFraction(frac1); PrintMathOption(choice1); PrintFraction(frac2); cout << " = "; Standardize(frac3); Reduce(frac3); PrintFraction(frac3); cout << endl; Pause();

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• Is 4-5 years the “Midlife Crisis” for a programming career?

  - by Jeffrey

  I’ve been programming C# professionally for a bit over 4 years now. For the past 4 years I’ve worked for a few small/medium companies ranging from “web/ads agencies”, small industry specific software shops to a small startup. I've been mainly doing "business apps" that involves using high-level programming languages (garbage collected) and my overall experience was that all of the works I’ve done could have been more professional. A lot of the things were done incorrectly (in a rush) mainly due to cost factor that people always wanted something “now” and with the smallest amount of spendable money. I kept on thinking maybe if I could work for a bigger companies or a company that’s better suited for programmers, or somewhere that's got the money and time to really build something longer term and more maintainable I may have enjoyed more in my career. I’ve never had a “mentor” that guided me through my 4 years career. I am pretty much blog / google / self taught programmer other than my bachelor IT degree. I’ve also observed another issue that most so called “senior” programmer in “my working environment” are really not that senior skill wise. They are “senior” only because they’ve been a long time programmer, but the code they write or the decisions they make are absolutely rubbish! They don't want to learn, they don't want to be better they just want to get paid and do what they've told to do which make sense and most of us are like that. Maybe that’s why they are where they are now. But I don’t want to become like them I want to be better. I’ve run into a mental state that I no longer intend to be a programmer for my future career. I started to think maybe there are better things out there to work on. The more blogs I read, the more “best practices” I’ve tried the more I feel I am drifting away from “my reality”. But I am not a great programmer otherwise I don't think I am where I am now. I think 4-5 years is a stage that can be a step forward career wise or a step out of where you are. I just wanted to hear what other have to say about what I’ve mentioned above and whether you’ve experienced similar situation in your past programming career and how you dealt with it. Thanks.

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• How to use unset() for this Linear Linked List in PHP

  - by Peter

  I'm writing a simple linear linked list implementation in PHP. This is basically just for practice... part of a Project Euler problem. I'm not sure if I should be using unset() to help in garbage collection in order to avoid memory leaks. Should I include an unset() for head and temp in the destructor of LLL? I understand that I'll use unset() to delete nodes when I want, but is unset() necessary for general clean up at any point? Is the memory map freed once the script terminates even if you don't use unset()? I saw this SO question, but I'm still a little unclear. Is the answer that you simply don't have to use unset() to avoid any sort of memory leaks associated with creating references? I'm using PHP 5.. btw. Unsetting references in PHP PHP references tutorial Here is the code - I'm creating references when I create $temp and $this-head at certain points in the LLL class: class Node { public $data; public $next; } class LLL { // The first node private $head; public function __construct() { $this->head = NULL; } public function insertFirst($data) { if (!$this->head) { // Create the head $this->head = new Node; $temp =& $this->head; $temp->data = $data; $temp->next = NULL; } else { // Add a node, and make it the new head. $temp = new Node; $temp->next = $this->head; $temp->data = $data; $this->head =& $temp; } } public function showAll() { echo "The linear linked list:<br/>&nbsp;&nbsp;"; if ($this->head) { $temp =& $this->head; do { echo $temp->data . " "; } while ($temp =& $temp->next); } else { echo "is empty."; } echo "<br/>"; } } Thanks!

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• Hot to get rid of memory allocations/deallocations in swig wrappers?

  - by Dmitriy Matveev

  I want to use swig for generation of read-only wrappers for a complex object. The object which I want to wrap will always be existent while I will read it. And also I will only use my wrappers at the time that object is existent, thus I don't need any memory management from SWIG. For following swig interface: %module test %immutable; %inline %{ struct Foo { int a; }; struct Bar { int b; Foo f; }; %} I will have a wrappers which will have a lot of garbage in generated interfaces and do useless work which will reduce performance in my case. Generated java wrapper for Bar class will be like this: public class Bar { private long swigCPtr; protected boolean swigCMemOwn; protected Bar(long cPtr, boolean cMemoryOwn) { swigCMemOwn = cMemoryOwn; swigCPtr = cPtr; } protected static long getCPtr(Bar obj) { return (obj == null) ? 0 : obj.swigCPtr; } protected void finalize() { delete(); } public synchronized void delete() { if (swigCPtr != 0) { if (swigCMemOwn) { swigCMemOwn = false; testJNI.delete_Bar(swigCPtr); } swigCPtr = 0; } } public int getB() { return testJNI.Bar_b_get(swigCPtr, this); } public Foo getF() { return new Foo(testJNI.Bar_f_get(swigCPtr, this), true); } public Bar() { this(testJNI.new_Bar(), true); } } I don't need 'swigCMemOwn' field in my wrapper since it always will be false. All code related to this field will also be useless. There are also unnecessary logic in native code: SWIGEXPORT jlong JNICALL Java_some_testJNI_Bar_1f_1get(JNIEnv *jenv, jclass jcls, jlong jarg1, jobject jarg1_) { jlong jresult = 0 ; struct Bar *arg1 = (struct Bar *) 0 ; Foo result; (void)jenv; (void)jcls; (void)jarg1_; arg1 = *(struct Bar **)&jarg1; result = ((arg1)->f); { Foo * resultptr = (Foo *) malloc(sizeof(Foo)); memmove(resultptr, &result, sizeof(Foo)); *(Foo **)&jresult = resultptr; } return jresult; } I don't need these calls to malloc and memmove. I want to force swig to resolve both of these problems, but don't know how. Is it possible?

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• Java template classes using generator or similar?

  - by Hugh Perkins

  Is there some library or generator that I can use to generate multiple templated java classes from a single template? Obviously Java does have a generics implementation itself, but since it uses type-erasure, there are lots of situations where it is less than adequate. For example, if I want to make a self-growing array like this: class EasyArray { T[] backingarray; } (where T is a primitive type), then this isn't possible. This is true for anything which needs an array, for example high-performance templated matrix and vector classes. It should probably be possible to write a code generator which takes a templated class and generates multiple instantiations, for different types, eg for 'double' and 'float' and 'int' and 'String'. Is there something that already exists that does this? Edit: note that using an array of Object is not what I'm looking for, since it's no longer an array of primitives. An array of primitives is very fast, and uses only as much space a sizeof(primitive) * length-of-array. An array of object is an array of pointers/references, that points to Double objects, or similar, which could be scattered all over the place in memory, require garbage collection, allocation, and imply a double-indirection for access. Edit2: good god, voted down for asking for something that probably doesn't currently exist, but is technically possible and feasible? Does that mean that people looking for ways to improve things have already left the java community? Edit3: Here is code to show the difference in performance between primitive and boxed arrays: int N = 10*1000*1000; double[]primArray = new double[N]; for( int i = 0; i < N; i++ ) { primArray[i] = 123.0; } Object[] objArray = new Double[N]; for( int i = 0; i < N; i++ ) { objArray[i] = 123.0; } tic(); primArray = new double[N]; for( int i = 0; i < N; i++ ) { primArray[i] = 123.0; } toc(); tic(); objArray = new Double[N]; for( int i = 0; i < N; i++ ) { objArray[i] = 123.0; } toc(); Results: double[] array: 148 ms Double[] array: 4614 ms Not even close!

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• SSH X11 not working

  - by azat

  I have a home and work computer, the home computer has a static IP address. If I ssh from my work computer to my home computer, the ssh connection works but X11 applications are not displayed. In my /etc/ssh/sshd_config at home: X11Forwarding yes X11DisplayOffset 10 X11UseLocalhost yes At work I have tried the following commands: xhost + home HOME_IP ssh -X home ssh -X HOME_IP ssh -Y home ssh -Y HOME_IP My /etc/ssh/ssh_config at work: Host * ForwardX11 yes ForwardX11Trusted yes My ~/.ssh/config at work: Host home HostName HOME_IP User azat PreferredAuthentications password ForwardX11 yes My ~/.Xauthority at work: -rw------- 1 azat azat 269 Jun 7 11:25 .Xauthority My ~/.Xauthority at home: -rw------- 1 azat azat 246 Jun 7 19:03 .Xauthority But it doesn't work After I make an ssh connection to home: $ echo $DISPLAY localhost:10.0 $ kate X11 connection rejected because of wrong authentication. X11 connection rejected because of wrong authentication. X11 connection rejected because of wrong authentication. X11 connection rejected because of wrong authentication. X11 connection rejected because of wrong authentication. X11 connection rejected because of wrong authentication. X11 connection rejected because of wrong authentication. X11 connection rejected because of wrong authentication. kate: cannot connect to X server localhost:10.0 I use iptables at home, but I've allowed port 22. According to what I've read that's all I need. UPD. With -vvv ... debug2: callback start debug2: x11_get_proto: /usr/bin/xauth list :0 2/dev/null debug1: Requesting X11 forwarding with authentication spoofing. debug2: channel 1: request x11-req confirm 1 debug2: client_session2_setup: id 1 debug2: fd 3 setting TCP_NODELAY debug2: channel 1: request pty-req confirm 1 ... When try to launch kate: debug1: client_input_channel_open: ctype x11 rchan 2 win 65536 max 16384 debug1: client_request_x11: request from 127.0.0.1 55486 debug2: fd 8 setting O_NONBLOCK debug3: fd 8 is O_NONBLOCK debug1: channel 2: new [x11] debug1: confirm x11 debug2: X11 connection uses different authentication protocol. X11 connection rejected because of wrong authentication. debug2: X11 rejected 2 i0/o0 debug2: channel 2: read failed debug2: channel 2: close_read debug2: channel 2: input open - drain debug2: channel 2: ibuf empty debug2: channel 2: send eof debug2: channel 2: input drain - closed debug2: channel 2: write failed debug2: channel 2: close_write debug2: channel 2: output open - closed debug2: X11 closed 2 i3/o3 debug2: channel 2: send close debug2: channel 2: rcvd close debug2: channel 2: is dead debug2: channel 2: garbage collecting debug1: channel 2: free: x11, nchannels 3 debug3: channel 2: status: The following connections are open: #1 client-session (t4 r0 i0/0 o0/0 fd 5/6 cc -1) #2 x11 (t7 r2 i3/0 o3/0 fd 8/8 cc -1) # The same as above repeate about 7 times kate: cannot connect to X server localhost:10.0 UPD2 Please provide your Linux distribution & version number. Are you using a default GNOME or KDE environment for X or something else you customized yourself? azat:~$ kded4 -version Qt: 4.7.4 KDE Development Platform: 4.6.5 (4.6.5) KDE Daemon: $Id$ Are you invoking ssh directly on a command line from a terminal window? What terminal are you using? xterm, gnome-terminal, or? How did you start the terminal running in the X environment? From a menu? Hotkey? or ? From terminal emulator `yakuake` Manualy press `Ctrl + N` and write commands Can you run xeyes from the same terminal window where the ssh -X fails? `xeyes` - is not installed But `kate` or another kde app is running Are you invoking the ssh command as the same user that you're logged into the X session as? From the same user UPD3 I also download ssh sources, and using debug2() write why it's report that version is different It see some cookies, and one of them is empty, another is MIT-MAGIC-COOKIE-1

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• GZip/Deflate Compression in ASP.NET MVC

  - by Rick Strahl

  A long while back I wrote about GZip compression in ASP.NET. In that article I describe two generic helper methods that I've used in all sorts of ASP.NET application from WebForms apps to HttpModules and HttpHandlers that require gzip or deflate compression. The same static methods also work in ASP.NET MVC. Here are the two routines:/// <summary> /// Determines if GZip is supported /// </summary> /// <returns></returns> public static bool IsGZipSupported() { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (!string.IsNullOrEmpty(AcceptEncoding) && (AcceptEncoding.Contains("gzip") || AcceptEncoding.Contains("deflate"))) return true; return false; } /// <summary> /// Sets up the current page or handler to use GZip through a Response.Filter /// IMPORTANT: /// You have to call this method before any output is generated! /// </summary> public static void GZipEncodePage() { HttpResponse Response = HttpContext.Current.Response; if (IsGZipSupported()) { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (AcceptEncoding.Contains("gzip")) { Response.Filter = new System.IO.Compression.GZipStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); Response.Headers.Remove("Content-Encoding"); Response.AppendHeader("Content-Encoding", "gzip"); } else { Response.Filter = new System.IO.Compression.DeflateStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); Response.Headers.Remove("Content-Encoding"); Response.AppendHeader("Content-Encoding", "deflate"); } } // Allow proxy servers to cache encoded and unencoded versions separately Response.AppendHeader("Vary", "Content-Encoding"); } The first method checks whether the client sending the request includes the accept-encoding for either gzip or deflate, and if if it does it returns true. The second function uses IsGzipSupported() to decide whether it should encode content and uses an Response Filter to do its job. Basically response filters look at the Response output stream as it's written and convert the data flowing through it. Filters are a bit tricky to work with but the two .NET filter streams for GZip and Deflate Compression make this a snap to implement. In my old code and even now in MVC I can always do:public ActionResult List(string keyword=null, int category=0) { WebUtils.GZipEncodePage(); …} to encode my content. And that works just fine. The proper way: Create an ActionFilterAttribute However in MVC this sort of thing is typically better handled by an ActionFilter which can be applied with an attribute. So to be all prim and proper I created an CompressContentAttribute ActionFilter that incorporates those two helper methods and which looks like this:/// <summary> /// Attribute that can be added to controller methods to force content /// to be GZip encoded if the client supports it /// </summary> public class CompressContentAttribute : ActionFilterAttribute { /// <summary> /// Override to compress the content that is generated by /// an action method. /// </summary> /// <param name="filterContext"></param> public override void OnActionExecuting(ActionExecutingContext filterContext) { GZipEncodePage(); } /// <summary> /// Determines if GZip is supported /// </summary> /// <returns></returns> public static bool IsGZipSupported() { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (!string.IsNullOrEmpty(AcceptEncoding) && (AcceptEncoding.Contains("gzip") || AcceptEncoding.Contains("deflate"))) return true; return false; } /// <summary> /// Sets up the current page or handler to use GZip through a Response.Filter /// IMPORTANT: /// You have to call this method before any output is generated! /// </summary> public static void GZipEncodePage() { HttpResponse Response = HttpContext.Current.Response; if (IsGZipSupported()) { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (AcceptEncoding.Contains("gzip")) { Response.Filter = new System.IO.Compression.GZipStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); Response.Headers.Remove("Content-Encoding"); Response.AppendHeader("Content-Encoding", "gzip"); } else { Response.Filter = new System.IO.Compression.DeflateStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); Response.Headers.Remove("Content-Encoding"); Response.AppendHeader("Content-Encoding", "deflate"); } } // Allow proxy servers to cache encoded and unencoded versions separately Response.AppendHeader("Vary", "Content-Encoding"); } } It's basically the same code wrapped into an ActionFilter attribute, which intercepts requests MVC requests to Controller methods and lets you hook up logic before and after the methods have executed. Here I want to override OnActionExecuting() which fires before the Controller action is fired. With the CompressContentAttribute created, it can now be applied to either the controller as a whole:[CompressContent] public class ClassifiedsController : ClassifiedsBaseController { … } or to one of the Action methods:[CompressContent] public ActionResult List(string keyword=null, int category=0) { … } The former applies compression to every action method, while the latter is selective and only applies it to the individual action method. Is the attribute better than the static utility function? Not really, but it is the standard MVC way to hook up 'filter' content and that's where others are likely to expect to set options like this. In fact,  you have a bit more control with the utility function because you can conditionally apply it in code, but this is actually much less likely in MVC applications than old WebForms apps since controller methods tend to be more focused. Compression Caveats Http compression is very cool and pretty easy to implement in ASP.NET but you have to be careful with it - especially if your content might get transformed or redirected inside of ASP.NET. A good example, is if an error occurs and a compression filter is applied. ASP.NET errors don't clear the filter, but clear the Response headers which results in some nasty garbage because the compressed content now no longer matches the headers. Another issue is Caching, which has to account for all possible ways of compression and non-compression that the content is served. Basically compressed content and caching don't mix well. I wrote about several of these issues in an old blog post and I recommend you take a quick peek before diving into making every bit of output Gzip encoded. None of these are show stoppers, but you have to be aware of the issues. Related Posts GZip Compression with ASP.NET Content ASP.NET GZip Encoding Caveats© Rick Strahl, West Wind Technologies, 2005-2012Posted in ASP.NET  MVC   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Thursday Community Keynote: "By the Community, For the Community"

  - by Janice J. Heiss

  Sharat Chander, JavaOne Community Chairperson, began Thursday's Community Keynote. As part of the morning’s theme of "By the Community, For the Community," Chander noted that 60% of the material at the 2012 JavaOne conference was presented by Java Community members. "So next year, when the call for papers starts, put-in your submissions," he urged.From there, Gary Frost, Principal Member of Technical Staff, AMD, expanded upon Sunday's Strategy Keynote exploration of Project Sumatra, an OpenJDK project targeted at bringing Java to heterogeneous computing platforms (which combine the CPU and the parallel processor of the GPU into a single piece of silicon). Sumatra entails enhancing the JVM to make maximum use of these advanced platforms. Within this development space, AMD created the Aparapi API, which converts Java bytecode into OpenCL for execution on such GPU devices. The Aparapi API was open sourced in September 2011.Whether it was zooming-in on a Mandelbrot set, "the game of life," or a swarm of 10,000 Dukes in a space-bound gravitational dance, Frost's demos, using an Aparapi/OpenCL implementation, produced stunningly faster display results. He indicated that the Java 9 timeframe is where they see Project Sumatra coming to ultimate fruition, employing the Lamdas of Java 8.Returning to the theme of the keynote, Donald Smith, Director, Java Product Management, Oracle, explored a mind map graphic demonstrating the importance of Community in terms of fostering innovation. "It's the sharing and mixing of culture, the diversity, and the rapid prototyping," he said. Within this topic, Smith, brought up a panel of representatives from Cloudera, Eclipse, Eucalyptus, Perrone Robotics, and Twitter--ideal manifestations of community and innovation in the world of Java.Marten Mickos, CEO, Eucalyptus Systems, explored his company's open source cloud software platform, written in Java, and used by gaming companies, technology companies, media companies, and more. Chris Aniszczyk, Operations Engineering,Twitter, noted the importance of the JVM in terms of their multiple-language development environment. Mike Olson, CEO, Cloudera, described his company's Apache Hadoop-based software, support, and training. Mike Milinkovich, Executive Director, Eclipse Foundation, noted that they have about 270 tools projects at Eclipse, with 267 of them written in Java. Milinkovich added that Eclipse will even be going into space in 2013, as part of the control software on various experiments aboard the International Space Station. Lastly, Paul Perrone, CEO, Perrone Robotics, detailed his company's robotics and automation software platform built 100% on Java, including Java SE and Java ME--"on rat, to cat, to elephant-sized systems." Milinkovic noted that communities are by nature so good at innovation because of their very openness--"The more open you make your innovation process, the more ideas are challenged, and the more developers are focused on justifying their choices all the way through the process."From there, Georges Saab, VP Development Java SE OpenJDK, continued the topic of innovation and helping the Java Community to "Make the Future Java." Martijn Verburg, representing the London Java Community (winner of a Duke's Choice Award 2012 for their activity in OpenJDK and JCP), soon joined Saab onstage. Verburg detailed the LJC's "Adopt a JSR" program--"to get day-to-day developers more involved in the innovation that's happening around them."  From its London launching pad, the innovative program has spread to Brazil, Morocco, Latvia, India, and more.Other active participants in the program joined Verburg onstage--Ben Evans, London Java Community; James Gough, Stackthread; Bruno Souza, SOUJava; Richard Warburton, jClarity; and Cecelia Borg, Oracle--OpenJDK Onboarding. Together, the group explored the goals and tasks inherent in the Adopt a JSR program--from organizing hack days (testing prototype implementations), to managing mailing lists and forums, to triaging issues, to evangelism—all with the goal of fostering greater community/developer involvement, but equally importantly, building better open standards. “Come join us, and make your ecosystem better!" urged Verburg.Paul Perrone returned to profile the latest in his company's robotics work around Java--including the AARDBOTS family of smaller robotic vehicles, running the Perrone MAX platform on top of the Java JVM. Perrone took his "Rumbles" four-wheeled robot out for a spin onstage--a roaming, ARM-based security-bot vehicle, complete with IR, ultrasonic, and "cliff" sensors (the latter, for the raised stage at JavaOne). As an ultimate window into the future of robotics, Perrone displayed a "head-set" controller--a sensor directed at the forehead to monitor brainwaves, for the someday-implementation of brain-to-robot control.Then, just when it seemed this might be the end of the day's futuristic offerings, a mystery voice from offstage pronounced "I've got some toys"--proving to be guest-visitor James Gosling, there to explore his cutting-edge work with Liquid Robotics. While most think of robots as something with wheels or arms or lasers, Gosling explained, the Liquid Robotics vehicle is an entirely new and innovative ocean-going 'bot. Looking like a floating surfboard, with an attached set of underwater wings, the autonomous devices roam the oceans using only the energy of ocean waves to propel them, and a single actuated rudder to steer. "We have to accomplish all guidance just by wiggling the rudder," Gosling said. The devices offer applications from self-installing weather buoy, to pollution monitoring station, to marine mammal monitoring device, to climate change data gathering, to even ocean life genomic sampling. The early versions of the vehicle used C code on very tiny industrial micro controllers, where they had to "count the bytes one at a time."  But the latest generation vehicles, which just hit the water a week or so ago, employ an ARM processor running Linux and the ARM version of JDK 7. Gosling explained that vehicle communication from remote locations is achieved via the Iridium satellite network. But because of the costs of this communication path, the data must be sent in very small bursts--using SBD short burst data. "It costs $1/kb, so that rules everything in the software design,” said Gosling. “If you were trying to stream a Netflix video over this, it would cost a million dollars a movie. …We don't have a 'big data' problem," he quipped. There are currently about 150 Liquid Robotics vehicles out traversing the oceans. Gosling demonstrated real time satellite tracking of several vehicles currently at sea, noting that Java is actually particularly good at AI applications--due to the language having garbage collection, which facilitates complex data structures. To close-out his time onstage, Gosling of course participated in the ceremonial Java tee-shirt toss out to the audience…In parting, Chander passed the JavaOne Community Chairperson baton to Stephen Chin, Java Technology Evangelist, Oracle. Onstage in full motorcycle gear, Chin noted that he'll soon be touring Europe by motorcycle, meeting Java Community Members and streaming live via UStream--the ultimate manifestation of community and technology!  He also reminded attendees of the upcoming JavaOne Latin America 2012, São Paulo, Brazil (December 4-6, 2012), and stated that the CFP (call for papers) at the conference has been extended for one more week. "Remember, December is summer in Brazil!" Chin said.

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• SQLAuthority News – Pluralsight Course Review – Practices for Software Startups – Part 2 of 2

  - by pinaldave

  This is the second part of the two part series of Practices for Software Startup Pluralsight Course. Please read the first part of this series over here. The course is written by Stephen Forte (Blog | Twitter). Stephen Forte is the Chief Strategy Officer of the venture backed company, Telerik. Personal Learning Schedule After these three sessions it was 6:30 am and time to do my own blog.  But for the rest of the day, I kept thinking about the course, and wanted to go back and finish.  I was wishing that I had woken up at 3 am so I could finish all at one go.  All day long I was digesting what I had learned.  At 10 pm, after my daughter had gone to bed, I sighed on again.  I was not disappointed by the long wait.  As I mentioned before, Stephen has started four to six companies, and all of them are very successful today. Here is the video I promised yesterday – it discusses the importance of Right Sizing Your Startup. The Heartbeat of Startup – Technology Stephen has combined all technology knowledge into one 30 minute session.  He discussed  how to start your project, how to deal with opinions, and how to deal with multiple ideas – every start up has multiple directions it can go. He spent a lot of time emphasized deciding which direction to go and how to decide which will be the best for you.  He called it a continuous development cycle. One of the biggest hazards for a start-up company is one person deciding the direction the company will go, until down the road another team member announces that there is a glitch in their part of the work and that everyone will have to start over.  Even though a team of two or five people can move quickly, often the decision has gone too long and cannot be easily fixed.   Stephen used an example from his own life:  he was biased for one type of technology, and his teammate for another.  In the end they opted for his teammate’s  choice , and in the end it was a good decision, even though he was unfamiliar with that particular program.  He argues that technology should not be a barrier to progress, that you cannot rely on your experience only.  This really spoke to me because I am a big fan of SQL, but I know there is more out there, and I should be more open to it.  I give my thanks to Stephen, I learned something in this module besides startups. Money, Success and Epic Win! The longest, but most interesting, the module was funding your start-up.  You need to fund the start-up right at the very beginning, if not done right you will run into trouble.  The good news is that a few years ago start-ups required a lot more money – think millions of dollars – but now start-ups can get off the ground for thousands.  Stephen used an example of a company that years ago would have needed a million dollars, but today could be started for $600.  It is true that things have changed, but you still need money.  For $600 you can start small and add dynamically, as needed.  But the truth is that if you have $600, $6000, or $6 million, it will be spent.  Don’t think of it as trying to save money, think of it as investing in your future.   You will need money, and you will need to (quickly) decide what you do with the money: shares, stakeholders, investing in a team, hiring a CEO.  This is so important because once you have money and start the company, the company IS your money.  It is your biggest currency – having a percentage of ownership in the company.  Investors will want percentages as repayment for their investment, and they will want a say in the business as well.  You will have to decide how far you will dilute your shares, and how the company will be divided, if at all.  If you don’t plan in advance, you will find that after gaining three or four investors, suddenly you are the minority owner in your own dream.  You need to understand funding carefully.  This single module is worth all the money you would have spent on the whole course alone.  I encourage everyone to listen to this single module even if they don’t watch any of the others.     Press End to Start the Game – Exists! The final module is exit strategies.  You did all this work, dealt with all political and legal issues.  What are you going to get out of it? The answer is simple: money.  Maybe you want your company to be bought out, for you talent to bring you a profit.  You can sell the company to someone and still head it.  Many options are available.  You could sell and still work as an employee but no longer own the company.  There are many exit strategies.  This is where all your hard work comes into play.  It is important not to feel fooled at any step.  There are so many good ideas that end up in the garbage because of poor planning, so that if you find yourself successful, you don’t want to blow it at this step!  The exit is important.  I thought that this aspect of the course was completely unique, and I loved Stephen’s point of view.  I was lost deep in thought after this module ended.  I actually took two hours worth of notes on this section alone – and it was only a three hour course.  I am planning on attending this course one more time next week, just to catch up on all the small bits of wisdom I’m sure I missed. Thank you Stephen for bringing your real world experience with us!  I recommend that everyone attends this course, even if they don’t want to begin their own start-up company. It was indeed a long day for me. Do not forget to read part 1 of this story and attend course Practices for Software Startup Pluralsight Course. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Best Practices, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Laissez les bon temps rouler! (Microsoft BI Conference 2010)

  - by smisner

  "Laissez les bons temps rouler" is a Cajun phrase that I heard frequently when I lived in New Orleans in the mid-1990s. It means "Let the good times roll!" and encapsulates a feeling of happy expectation. As I met with many of my peers and new acquaintances at the Microsoft BI Conference last week, this phrase kept running through my mind as people spoke about their plans in their respective businesses, the benefits and opportunities that the recent releases in the BI stack are providing, and their expectations about the future of the BI stack. Notwithstanding some jabs here and there to point out the platform is neither perfect now nor will be anytime soon (along with admissions that the competitors are also not perfect), and notwithstanding several missteps by the event organizers (which I don't care to enumerate), the overarching mood at the conference was positive. It was a refreshing change from the doom and gloom hovering over several conferences that I attended in 2009. Although many people expect economic hardships to continue over the coming year or so, everyone I know in the BI field is busier than ever and expects to stay busy for quite a while. Self-Service BI Self-service was definitely a theme of the BI conference. In the keynote, Ted Kummert opened with a look back to a fairy tale vision of self-service BI that he told in 2008. At that time, the fairy tale future was a time when "every end user was able to use BI technologies within their job in order to move forward more effectively" and transitioned to the present time in which SQL Server 2008 R2, Office 2010, and SharePoint 2010 are available to deliver managed self-service BI. This set of technologies is presumably poised to address the needs of the 80% of users that Kummert said do not use BI today. He proceeded to outline a series of activities that users ought to be able to do themselves--from simple changes to a report like formatting or an addtional data visualization to integration of an additional data source. The keynote then continued with a series of demonstrations of both current and future technology in support of self-service BI. Some highlights that interested me: PowerPivot, of course, is the flagship product for self-service BI in the Microsoft BI stack. In the TechEd keynote, which was open to the BI conference attendees, Amir Netz (twitter) impressed the audience by demonstrating interactivity with a workbook containing 100 million rows. He upped the ante at the BI keynote with his demonstration of a future-state PowerPivot workbook containing over 2 billion records. It's important to note that this volume of data is being processed by a server engine, and not in the PowerPivot client engine. (Yes, I think it's impressive, but none of my clients are typically wrangling with 2 billion records at a time. Maybe they're thinking too small. This ability to work quickly with large data sets has greater implications for BI solutions than for self-service BI, in my opinion.) Amir also demonstrated KPIs for the future PowerPivot, which appeared to be easier to implement than in any other Microsoft product that supports KPIs, apart from simple KPIs in SharePoint. (My initial reaction is that we have one more place to build KPIs. Great. It's confusing enough. I haven't seen how well those KPIs integrate with other BI tools, which will be important for adoption.) One more PowerPivot feature that Amir showed was a graphical display of the lineage for calculations. (This is hugely practical, especially if you build up calculations incrementally. You can more easily follow the logic from calculation to calculation. Furthermore, if you need to make a change to one calculation, you can assess the impact on other calculations.) Another product demonstration will be available within the next 30 days--Pivot for Reporting Services. If you haven't seen this technology yet, check it out at www.getpivot.com. (It definitely has a wow factor, but I'm skeptical about its practicality. However, I'm looking forward to trying it out with data that I understand.) Michael Tejedor (twitter) demonstrated a feature that I think is really interesting and not emphasized nearly enough--overshadowed by PowerPivot, no doubt. That feature is the Microsoft Business Intelligence Indexing Connector, which enables search of the content of Excel workbooks and Reporting Services reports. (This capability existed in MOSS 2007, but was more cumbersome to implement. The search results in SharePoint 2010 are not only cooler, but more useful by describing whether the content is found in a table or a chart, for example.) This may yet be the dawning of the age of self-service BI - a phrase I've heard repeated from time to time over the last decade - but I think BI professionals are likely to stay busy for a long while, and need not start looking for a new line of work. Kummert repeatedly referenced strategic BI solutions in contrast to self-service BI to emphasize that self-service BI is not a replacement for the services that BI professionals provide. After all, self-service BI does not appear magically on user desktops (or whatever device they want to use). A supporting infrastructure is necessary, and grows in complexity in proportion to the need to simplify BI for users. It's one thing to hear the party line touted by Microsoft employees at the BI keynote, but it's another to hear from the people who are responsible for implementing and supporting it within an organization. Rob Collie (blog | twitter), Kasper de Jonge (blog | twitter), Vidas Matelis (site | twitter), and I were invited to join Andrew Brust (blog | twitter) as he led a Birds of a Feather session at TechEd entitled "PowerPivot: Is It the BI Deal-Changer for Developers and IT Pros?" I would single out the prevailing concern in this session as the issue of control. On one side of this issue were those who were concerned that they would lose control once PowerPivot is implemented. On the other side were those who believed that data should be freely accessible to users in PowerPivot, and even acknowledgment that users would get the data they want even if it meant they would have to manually enter into a workbook to have it ready for analysis. For another viewpoint on how PowerPivot played out at the conference, see Rob Collie's observations. Collaborative BI I have been intrigued by the notion of collaborative BI for a very long time. Before I discovered BI, I was a Lotus Notes developer and later a manager of developers, working in a software company that enabled collaboration in the legal industry. Not only did I help create collaborative systems for our clients, I created a complete project management from the ground up to collaboratively manage our custom development work. In that case, collaboration involved my team, my client contacts, and me. I was also able to produce my own BI from that system as well, but didn't know that's what I was doing at the time. Only in recent years has SharePoint begun to catch up with the capabilities that I had with Lotus Notes more than a decade ago. Eventually, I had the opportunity at that job to formally investigate BI as another product offering for our software, and the rest - as they say - is history. I built my first data warehouse with Scott Cameron (who has also ventured into the authoring world by writing Analysis Services 2008 Step by Step and was at the BI Conference last week where I got to reminisce with him for a bit) and that began a career that I never imagined at the time. Fast forward to 2010, and I'm still lauding the virtues of collaborative BI, if only the tools will catch up to my vision! Thus, I was anxious to see what Donald Farmer (blog | twitter) and Rita Sallam of Gartner had to say on the subject in their session "Collaborative Decision Making." As I suspected, the tools aren't quite there yet, but the vendors are moving in the right direction. One thing I liked about this session was a non-Microsoft perspective of the state of the industry with regard to collaborative BI. In addition, this session included a better demonstration of SharePoint collaborative BI capabilities than appeared in the BI keynote. Check out the video in the link to the session to see the demonstration. One of the use cases that was demonstrated was linking from information to a person, because, as Donald put it, "People don't trust data, they trust people." The Microsoft BI Stack in General A question I hear all the time from students when I'm teaching is how to know what tools to use when there is overlap between products in the BI stack. I've never taken the time to codify my thoughts on the subject, but saw that my friend Dan Bulos provided good insight on this topic from a variety of perspectives in his session, "So Many BI Tools, So Little Time." I thought one of his best points was that ideally you should be able to design in your tool of choice, and then deploy to your tool of choice. Unfortunately, the ideal is yet to become real across the platform. The closest we come is with the RDL in Reporting Services which can be produced from two different tools (Report Builder or Business Intelligence Development Studio's Report Designer), manually, or by a third-party or custom application. I have touted the idea for years (and publicly said so about 5 years ago) that eventually more products would be RDL producers or consumers, but we aren't there yet. Maybe in another 5 years. Another interesting session that covered the BI stack against a backdrop of competitive products was delivered by Andrew Brust. Andrew did a marvelous job of consolidating a lot of information in a way that clearly communicated how various vendors' offerings compared to the Microsoft BI stack. He also made a particularly compelling argument about how the existence of an ecosystem around the Microsoft BI stack provided innovation and opportunities lacking for other vendors. Check out his presentation, "How Does the Microsoft BI Stack...Stack Up?" Expo Hall I had planned to spend more time in the Expo Hall to see who was doing new things with the BI stack, but didn't manage to get very far. Each time I set out on an exploratory mission, I got caught up in some fascinating conversations with one or more of my peers. I find interacting with people that I meet at conferences just as important as attending sessions to learn something new. There were a couple of items that really caught me eye, however, that I'll share here. Pragmatic Works. Whether you develop SSIS packages, build SSAS cubes, or author SSRS reports (or all of the above), you really must take a look at BI Documenter. Brian Knight (twitter) walked me through the key features, and I must say I was impressed. Once you've seen what this product can do, you won't want to document your BI projects any other way. You can download a free single-user database edition, or choose from more feature-rich standard or professional editions. Microsoft Press ebooks. I also stopped by the O'Reilly Media booth to meet some folks that one of my acquisitions editors at Microsoft Press recommended. In case you haven't heard, Microsoft Press has partnered with O'Reilly Media for distribution and publishing. Apart from my interest in learning more about O'Reilly Media as an author, an advertisement in their booth caught me eye which I think is a really great move. When you buy Microsoft Press ebooks through the O'Reilly web site, you can receive it in any (or all) of the following formats where possible: PDF, epub, .mobi for Kindle and .apk for Android. You also have lifetime DRM-free access to the ebooks. As someone who is an avid collector of books, I fnd myself running out of room for storage. In addition, I travel a lot, and it's hard to lug my reference library with me. Today's e-reader options make the move to digital books a more viable way to grow my library. Having a variety of formats means I am not limited to a single device, and lifetime access means I don't have to worry about keeping track of where I've stored my files. Because the e-books are DRM-free, I can copy and paste when I'm compiling notes, and I can print pages when necessary. That's a winning combination in my mind! Overall, I was pleased with the BI conference. There were many more sessions that I couldn't attend, either because the room was full when I got there or there were multiple sessions running concurrently that I wanted to see. Fortunately, many of the sessions are accessible for viewing online at http://www.msteched.com/2010/NorthAmerica along with the TechEd sessions. You can spot the BI sessions by the yellow skyline on the title slide of the presentation as shown below. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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