specification pattern - Page 247

Arranging models, views, controllers in a Kohana 3 project

- by Pekka

I'm looking at how to set up a mid-sized web application with Kohana 3. I have implemented MVC patterns in the past but never worked against a "formalized" MVC framework so I'm still getting my head around the terminology - toying around with basic examples, building views and templates, and so on. I'm progressing fairly well but I want to set up a real-world web project (one of my own that I've been planning for quite some time now) as a learning object. I learn best by example, but example-based documentation is a bit sparse for Kohana 3 right now - they say so themselves on the site. While I'm not worried about getting into the framework soon enough, I'm a bit concerned about arranging a healthily structured code base from the start - i.e. how to split up controllers, how to name them, and how to separate the functionality into the appropriate models. My application could, in its core, be described as a business directory with a main businesses table. Businesses can be listed by category and by street name. Each business has a detail page. Business owners can log in and edit their business's entry. Businesses can post offers into an offers table. I know this is pretty vague, but I don't want to cram too much information into this question. I'll be more than happy to go into more detail if needed. Supposing I have all the basic functionality worked out and in place already - list all businesses, edit business, list businesses by street name, create offer, and so on, and I'm just looking for how to fit the functionality into a MVC pattern and into a Kohana application structure that can be easily extended: Do you know real-life, publicly accessible examples of "database-heavy" applications like directories, online communities... with a log-in area built on Kohana 3 where I could take a peek how they do it? Are there conventions or best practices on how to structure an extendable login area for end users in a Kohana project that is not only able to handle a business directory page, but further products on separate pages as well? Do you know application structuring HOWTOs or best practices for Kohana 3 not mentioned in the user guide and the inofficial Wiki? Have you built something similar and could give me some recommendations?

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Haskell: how to get through 'no instance for' ?

- by artemave

I am learning Haskell. I am on the 8th chapter of this book. The main thing I've learned so far is that Haskell is very unfriendly to me and it bites my ass where possible. Moreover... Heck! Enough mourning, to business. Here is the code: module GlobRegex ( globToRegex, matchesGlob ) where import Text.Regex.Posix import Text.Regex.Posix.String import Text.Regex.Base.RegexLike data CaseOpt = Case | NoCase deriving (Eq) matchesGlob :: String -> String -> CaseOpt -> Bool matchesGlob name pat caseopt = match regex name where regex = case caseopt of NoCase -> makeRegexOpts (defaultCompOpt + compIgnoreCase) defaultExecOpt (globToRegex pat) Case -> makeRegex (globToRegex pat) globToRegex :: String -> String ... And here is how it fails to compile: Prelude Text.Regex.Posix Text.Regex.Base.RegexLike> :load globtoregex\GlobRegex. hs [1 of 1] Compiling GlobRegex ( globtoregex\GlobRegex.hs, interpreted ) globtoregex\GlobRegex.hs:14:31: No instance for (RegexLike regex [Char]) arising from a use of `match' at globtoregex\GlobRegex.hs:14:31-46 Possible fix: add an instance declaration for (RegexLike regex [Char]) In the expression: match regex name In the definition of `matchesGlob': matchesGlob name pat caseopt = match regex name where regex = case caseopt of { NoCase -> makeRegexOpts (defaultCompOpt + compIgnoreCase) defaultExecOpt (globToRegex pat) Case -> makeRegex (globToRegex pat) } globtoregex\GlobRegex.hs:17:23: No instance for (RegexMaker regex CompOption execOpt String) arising from a use of `makeRegex' at globtoregex\GlobRegex.hs:17:23-49 Possible fix: add an instance declaration for (RegexMaker regex CompOption execOpt String) In the expression: makeRegex (globToRegex pat) In a case alternative: Case -> makeRegex (globToRegex pat) In the expression: case caseopt of { NoCase -> makeRegexOpts (defaultCompOpt + compIgnoreCase) defaultExecOpt (globToRegex p at) Case -> makeRegex (globToRegex pat) } Failed, modules loaded: none. To my best understanding, Text.Regex.Posix.String provides instances for RegexLike Regex String and RegexMaker Regex CompOption ExecOption String, so it should work. On the other hand, I can see that regex in the error message is type variable, not a concrete type, so, perhaps not... Anyway, this is where I am stuck. May be there is a common pattern for resolving no instance for type of problems? Or, in Haskell terms, instance of SmartGuess typeclass for no instance for?

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My block is not retaining some of its objects

- by Drew Crawford

From the Blocks documentation: In a reference-counted environment, by default when you reference an Objective-C object within a block, it is retained. This is true even if you simply reference an instance variable of the object. I am trying to implement a completion handler pattern, where a block is given to an object before the work is performed and the block is executed by the receiver after the work is performed. Since I am being a good memory citizen, the block should own the objects it references in the completion handler and then they will be released when the block goes out of scope. I know enough to know that I must copy the block to move it to the heap since the block will survive the stack scope in which it was declared. However, one of my objects is getting deallocated unexpectedly. After some playing around, it appears that certain objects are not retained when the block is copied to the heap, while other objects are. I am not sure what I am doing wrong. Here's the smallest test case I can produce: typedef void (^ActionBlock)(UIView*); In the scope of some method: NSObject *o = [[[NSObject alloc] init] autorelease]; mailViewController = [[[MFMailComposeViewController alloc] init] autorelease]; NSLog(@"o's retain count is %d",[o retainCount]); NSLog(@"mailViewController's retain count is %d",[mailViewController retainCount]); ActionBlock myBlock = ^(UIView *view) { [mailViewController setCcRecipients:[NSArray arrayWithObjects:@"[email protected]",nil]]; [o class]; }; NSLog(@"mailViewController's retain count after the block is %d",[mailViewController retainCount]); NSLog(@"o's retain count after the block is %d",[o retainCount]); Block_copy(myBlock); NSLog(@"o's retain count after the copy is %d",[o retainCount]); NSLog(@"mailViewController's retain count after the copy is %d",[mailViewController retainCount]); I expect both objects to be retained by the block at some point, and I certainly expect their retain counts to be identical. Instead, I get this output: o's retain count is 1 mailViewController's retain count is 1 mailViewController's retain count after the block is 1 o's retain count after the block is 1 o's retain count after the copy is 2 mailViewController's retain count after the copy is 1 o (subclass of NSObject) is getting retained properly and will not go out of scope. However mailViewController is not retained and will be deallocated before the block is run, causing a crash.

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Validate a string in a table in SQL Server - CLR function or T-SQL (Question updated)

- by Ashish Gupta

I need to check If a column value (string) in SQL server table starts with a small letter and can only contain '_', '-', numbers and alphabets. I know I can use a SQL server CLR function for that. However, I am trying to implement that validation using a scalar UDF and could make very little here...I can use 'NOT LIKE', but I am not sure how to make sure I validate the string irrespective of the order of characters or in other words write a pattern in SQL for this. Am I better off using a SQL CLR function? Any help will be appreciated.. Thanks in advance Thank you everyone for their comments. This morning, I chose to go CLR function way. For the purpose of what I was trying to achieve, I created one CLR function which does the validation of an input string and have that called from a SQL UDF and It works well. Just to measure the performance of t-SQL UDF using SQL CLR function vs t- SQL UDF, I created a SQL CLR function which will just check if the input string contains only small letters, it should return true else false and have that called from a UDF (IsLowerCaseCLR). After that I also created a regular t-SQL UDF(IsLowerCaseTSQL) which does the same thing using the 'NOT LIKE'. Then I created a table (Person) with columns Name(varchar) and IsValid(bit) columns and populate that with names to test. Data :- 1000 records with 'Ashish' as value for Name column 1000 records with 'ashish' as value for Name column then I ran the following :- UPDATE Person Set IsValid=1 WHERE dbo.IsLowerCaseTSQL (Name) Above updated 1000 records (with Isvalid=1) and took less than a second. I deleted all the data in the table and repopulated the same with same data. Then updated the same table using Sql CLR UDF (with Isvalid=1) and this took 3 seconds! If update happens for 5000 records, regular UDF takes 0 seconds compared to CLR UDF which takes 16 seconds! I am very less knowledgeable on t-SQL regular expression or I could have tested my actual more complex validation criteria. But I just wanted to know, even I could have written that, would that have been faster than the SQL CLR function considering the example above. Are we using SQL CLR because we can implement we can implement lot richer logic which would have been difficult otherwise If we write in regular SQL. Sorry for this long post. I just want to know from the experts. Please feel free to ask if you could not understand anything here. Thank you again for your time.

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RegEx strip html tags problem

- by Aleksandar Mirilovic

Hi, I've tried to strip html tags using regex replace with pattern "<[^]*" from word generated html that looks like this: <html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:st1="urn:schemas-microsoft-com:office:smarttags" xmlns="http://www.w3.org/TR/REC-html40"> <head> <meta http-equiv=Content-Type content="text/html; charset=iso-8859-2"> <meta name=Generator content="Microsoft Word 11 (filtered medium)"> <o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place" downloadurl="http://www.5iantlavalamp.com/"/>  <style>  </style> </head> Everything works fine except for the bolded lines above, anybody got ideas how to match the them to? Thanks, Aleksandar

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imagick showing script url instead of image

- by Raz

Hi, currently i'm trying to use imagick to generate some images without saving them on the server and then outputting to the browser, my method of choice was image magic with the imagick extension for php. I read the documentation, and i'm sure the package is installed on my machine (windows xp, with xampp). the class is installed imagick module enabled imagick module version 2.0.0-alpha imagick classes Imagick, ImagickDraw, ImagickPixel, ImagickPixelIterator ImageMagick version ImageMagick 6.3.3 04/21/07 Q16 http://www.imagemagick.org ImageMagick release date 04/21/07 ImageMagick Number of supported formats: 164 ImageMagick Supported formats A, ART, AVI, AVS, B, BIE, BMP, BMP2, BMP3, C, CACHE, CAPTION, CIN, CIP, CLIP, CLIPBOARD, CMYK, CMYKA, CUR, CUT, DCM, DCX, DFONT, DPS, DPX, EMF, EPDF, EPI, EPS, EPS2, EPS3, EPSF, EPSI, EPT, EPT2, EPT3, FAX, FITS, FRACTAL, FTS, G, G3, GIF, GIF87, GRADIENT, GRAY, HISTOGRAM, HTM, HTML, ICB, ICO, ICON, INFO, JBG, JBIG, JNG, JP2, JPC, JPEG, JPG, JPX, K, LABEL, M, M2V, MAP, MAT, MATTE, MIFF, MNG, MONO, MPC, MPEG, MPG, MSL, MSVG, MTV, MVG, NULL, O, OTB, OTF, PAL, PALM, PAM, PATTERN, PBM, PCD, PCDS, PCL, PCT, PCX, PDB, PDF, PFA, PFB, PGM, PGX, PICON, PICT, PIX, PJPEG, PLASMA, PNG, PNG24, PNG32, PNG8, PNM, PPM, PREVIEW, PS, PS2, PS3, PSD, PTIF, PWP, R, RAS, RGB, RGBA, RGBO, RLA, RLE, SCR, SCT, SFW, SGI, SHTML, STEGANO, SUN, SVG, SVGZ, TEXT, TGA, THUMBNAIL, TIFF, TILE, TIM, TTC, TTF, TXT, UIL, UYVY, VDA, VICAR, VID, VIFF, VST, WBMP, WMF, WMFWIN32, WMZ, WPG, X, XBM, XC, XCF, XPM, XV, XWD, Y, YCbCr, YCbCrA, YUV this is from the phpinfo so i know i have it installed, the thing is when i try to generate an image and save it, it works flawlessly, but when i try to output the image directly, i get the script url as an image $draw = new ImagickDraw(); $draw->setFont('AnkeCalligraph.TTF'); $draw->setFontSize(52); $draw->annotation(110, 110, "Hello World!"); $draw->annotation(50, 220, "Hello World!"); $canvas = new Imagick('./pictures/test_live.PNG'); $canvas->drawImage($draw); $canvas->setImageFormat('png'); header("Content-Type: image/png"); echo $canvas; this is the code used. if i use writeimage, then the file on the server is created with no problems. does anyone have any ideas what i'm doing wrong ?

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Flash video playing on top of everything else in IE7

- by Brett

Hi everyone, I've been spending hours now reading up on IE7's issue with rendering Flash content on top of other elements, particularly navigation menus (this is often a problem with dropdown menus and Flash ad banners, for example). I've tried a few of the suggested solutions but none have worked for me so far. I'll do my best to explain the circumstances, and would appreciate any advice in the matter! Update At Mercator's request, I am providing a large code-sample to assist in any advice you might have. Consider the HTML below: <body> <div id="page-wrap"> <div id="content-wrap"> <div id="main"> <h1>Page Title</h1> <p>Paragraph text before video.</p> <div class="video-container"> <script type="text/javascript"> AC_FL_RunContent('id','player','name','player','width','480','height','294','src','player','allowscriptaccess','always','allowfullscreen','true','flashvars','file=mp4/VIDEO_FILE.mp4','movie','player' ); //end AC code </script> <noscript> <object id="player" classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" name="player" width="480" height="294"> <param name="wmode" value="transparent" /> <param name="movie" value="player.swf" /> <param name="allowfullscreen" value="true" /> <param name="allowscriptaccess" value="always" /> <param name="flashvars" value="file=mp4/VIDEO_FILE.mp4" /> <embed wmode="transparent" type="application/x-shockwave-flash" id="player2" name="player2" src="player.swf" width="480" height="294" allowscriptaccess="always" allowfullscreen="true" flashvars="file=mp4/VIDEO_FILE.mp4" ></embed> </object> </noscript> </div> <p>Paragraph after video.</p> </div> <div id="subContent"> <p>Sub-content.</p> </div> <div id="content-clear"></div> </div> </div> <div id="footpanel"> <ul id="mainpanel"> <li id="panel-link"><a href="#"><span class="icon"></span>Panel Link</a> <div class="subpanel"> <h3><span> – </span>Panel Link</h3> <ul> <li><p>Revealed content</p></li> </ul> </div> </li> </ul> </div>  </body> Below are the non-presentational CSS selectors that apply to the divs above: body { /*no positioning styles applied */ } #page-wrap { width: 100%; } #content-wrap { width: 960px; margin 0 auto; } #main { float: left; width: 573px; } .video-container { position: relative; width: 480px; z-index: 1; } #sub { float: left; width: 347px; } #content-clear { clear: both; } #foot-panel { position: fixed; width: 94%; bottom: 0; left: 0; z-index: 3000; } ul#main-panel { float: left; } The footpanel uses jQuery-powered flyout menus, if that provides any further context. These menus have z-indexes in the 300X range to appear above the footpanel. The Flash in question is JW player playing a flash video or mp4. Currently, the object and embed tags are inside a container div. My understanding of previous solutions was that the combination of the param changes and the positioning/z-index change on the container div should have resolved the issue. Alas, it is not so. The player resides on top of the footpanel. Other information that may or may not be helpful is that the page is XHTML 1.0 Transitional and that Dreamweaver reports 1 error in the HTML code: <embed> is not in the XHTML 1.0 specification. This fact does not prevent the video from being viewed in any browser tested, and the page still displays correctly in FF. Thanks in advance!

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Regex slow on Windows Server 2008

- by pjmyburg

Hi I have a situation where my regular expressions compile extremely slowly on Windows Server 2008. I wrote a small console application to highlight this issue. The app generates its own input and builds up a Regex from words in an XML file. I built a release version of this app and ran it both on my personal laptop (running XP) and the Windows 2008 server. The regular expression took 0.21 seconds to compile on my laptop, but 23 seconds to compile on the server. Any ideas what could be causing this? The problem is only on first use of the Regex (when it is first compiled - thereafter it is fine) I have also found another problem - when using \s+ in the regular expression on the same Windows 2008 server, the memory balloons (uses 4GB+) and the compilation of the Regex never finishes. Is there a known issue with Regex and 64 bit .net? Is there a fix/patch available for this? I cannot really find any info on the net, but I have found a few articles about this same issues in Framework 2.0 - surely this has been fixed by now? More info: The server is running the 64 bit version of the .net framework (3.5 SP1) and on my laptop I have Visual Studio 2008 and the 3.5 framework installed. The regular expression is of the following pattern: ^word$|^word$|^word$ and is constructed with the following flags: RegexOptions.IgnoreCase | RegexOptions.Compiled Edit: Here is a code snippet: StringBuilder regexString = new StringBuilder(); if (!String.IsNullOrEmpty(fileLocation)) { XmlTextReader textReader = new XmlTextReader(fileLocation); textReader.Read(); while (textReader.Read()) { textReader.MoveToElement(); if (textReader.Name == "word") { regexString.Append("^" + textReader.GetAttribute(0) + "$|"); } } ProfanityFilter = new Regex(regexString.ToString(0, regexString.Length - 1), RegexOptions.IgnoreCase | RegexOptions.Compiled); } DateTime time = DateTime.Now; Console.WriteLine("\nIsProfane:\n" + ProfanityFilter.IsMatch("test")); Console.WriteLine("\nTime: " + (DateTime.Now - time).TotalSeconds); Console.ReadKey(); This results in a time of 0.21 seconds on my laptop and 23 seconds on the 2008 server. The XML file consists of 168 words in the following format: <word text="test" />

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Succinct introduction to C++/CLI for C#/Haskell/F#/JS/C++/... programmer

- by Henrik

Hello everybody, I'm trying to write integrations with the operating system and with things like active directory and Ocropus. I know a bunch of programming languages, including those listed in the title. I'm trying to learn exactly how C++/CLI works, but can't find succinct, exact and accurate descriptions online from the searching that I have done. So I ask here. Could you tell me the pitfalls and features of C++/CLI? Assume I know all of C# and start from there. I'm not an expert in C++, so some of my questions' answers might be "just like C++", but could say that I am at C#. I would like to know things like: Converting C++ pointers to CLI pointers, Any differences in passing by value/doubly indirect pointers/CLI pointers from C#/C++ and what is 'recommended'. How do gcnew, __gc, __nogc work with Polymorphism Structs Inner classes Interfaces The "fixed" keyword; does that exist? Compiling DLLs loaded into the kernel with C++/CLI possible? Loaded as device drivers? Invoked by the kernel? What does this mean anyway (i.e. to load something into the kernel exactly; how do I know if it is?)? L"my string" versus "my string"? wchar_t? How many types of chars are there? Are we safe in treating chars as uint32s or what should one treat them as to guarantee language indifference in code? Finalizers (~ClassName() {}) are discouraged in C# because there are no garantuees they will run deterministically, but since in C++ I have to use "delete" or use copy-c'tors as to stack allocate memory, what are the recommendations between C#/C++ interactions? What are the pitfalls when using reflection in C++/CLI? How well does C++/CLI work with the IDisposable pattern and with SafeHandle, SafeHandleZeroOrMinusOneIsInvalid? I've read briefly about asynchronous exceptions when doing DMA-operations, what are these? Are there limitations you impose upon yourself when using C++ with CLI integration rather than just doing plain C++? Attributes in C++ similar to Attributes in C#? Can I use the full meta-programming patterns available in C++ through templates now and still have it compile like ordinary C++? Have you tried writing C++/CLI with boost? What are the optimal ways of interfacing the boost library with C++/CLI; can you give me an example of passing a lambda expression to an iterator/foldr function? What is the preferred way of exception handling? Can C++/CLI catch managed exceptions now? How well does dynamic IL generation work with C++/CLI? Does it run on Mono? Any other things I ought to know about?

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Succinct introduction to C++/CLI for C#/Haskell/F#/JS/C++/... programmer

- by Henrik

Hello everybody, I'm trying to write integrations with the operating system and with things like active directory and Ocropus. I know a bunch of programming languages, including those listed in the title. I'm trying to learn exactly how C++/CLI works, but can't find succinct, exact and accurate descriptions online from the searching that I have done. So I ask here. Could you tell me the pitfalls and features of C++/CLI? Assume I know all of C# and start from there. I'm not an expert in C++, so some of my questions' answers might be "just like C++", but could say that I am at C#. I would like to know things like: Converting C++ pointers to CLI pointers, Any differences in passing by value/doubly indirect pointers/CLI pointers from C#/C++ and what is 'recommended'. How do gcnew, __gc, __nogc work with Polymorphism Structs Inner classes Interfaces The "fixed" keyword; does that exist? Compiling DLLs loaded into the kernel with C++/CLI possible? Loaded as device drivers? Invoked by the kernel? What does this mean anyway (i.e. to load something into the kernel exactly; how do I know if it is?)? L"my string" versus "my string"? wchar_t? How many types of chars are there? Are we safe in treating chars as uint32s or what should one treat them as to guarantee language indifference in code? Finalizers (~ClassName() {}) are discouraged in C# because there are no garantuees they will run deterministically, but since in C++ I have to use "delete" or use copy-c'tors as to stack allocate memory, what are the recommendations between C#/C++ interactions? What are the pitfalls when using reflection in C++/CLI? How well does C++/CLI work with the IDisposable pattern and with SafeHandle, SafeHandleZeroOrMinusOneIsInvalid? I've read briefly about asynchronous exceptions when doing DMA-operations, what are these? Are there limitations you impose upon yourself when using C++ with CLI integration rather than just doing plain C++? Attributes in C++ similar to Attributes in C#? Can I use the full meta-programming patterns available in C++ through templates now and still have it compile like ordinary C++? Have you tried writing C++/CLI with boost? What are the optimal ways of interfacing the boost library with C++/CLI; can you give me an example of passing a lambda expression to an iterator/foldr function? What is the preferred way of exception handling? Can C++/CLI catch managed exceptions now? How well does dynamic IL generation work with C++/CLI? Does it run on Mono? Any other things I ought to know about?

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Looking for efficient scaling patterns for Silverlight application with distributed text-file data s

- by Edward Tanguay

I'm designing a Silverlight software solution for students and teachers to record flashcards, e.g. words and phrases that students find while reading and errors that teachers notice while teaching. Requirements are: each person publishes his own flashcards in a file on a web server, e.g. http://:www.mywebserver.com/flashcards.txt other people subscribe to that person's flashcards by using a Silverlight flashcard reader that I have developed and entering the URLs of flashcard files they want to subscribe to, URLs and imported flashcards being saved in IsolatedStorage the flashcards.txt file has the following simple format: title, then blocks of question/answers: Jim Smith's flashcards from English class 53-222, winter semester 2009 ==fla Das kann nicht sein. That can't be. ==fla Es sei denn, er kommt nicht. Unless he doesn't come. The user then makes public the URL to his flashcard file and other readers begin reading in his flashcards. In order to lower the bar for non-technical users to contribute, it will even be possible for them to save this text in a Google Document, which they publish and distribute the URL. The flashcard readers will then recognize it is a google document and perform the necessary screen scraping to get at the raw text. I have two technical questions about this approach: What is a best way to plan now for scalability issues: e.g. if your reader is subscribed to 10 flashcard files that are each 200K, it will have to download 2MB of text just to find out if any new flashcards are available. Or can I somehow accurately and consistently get at the last update date/time of text files on servers and published google docs? Each reader will have the ability to allow the person to test himself on imported flashcards and add meta information to them, e.g. categorize them, edit them, etc. This information will be stored in IsolatedStorage along with the important flashcards themselves. What is a good pattern to allow these readers to share and synchronize this meta data, e.g. so when you are looking at a flashcard you can see that 5 other people have made corrections to it. The best solution I can think of now is that the Silverlight readers will have to republish their data to a central database, but then there is the problem of uniquely identifying each flashcard, the best approach seems to be URL + position-in-file, or even better URL + original text of both question and answer fields, but both of these have their obvious drawbacks. The main requirement is that the bar for participation is kept as low as possible, i.e. type text in a google document, publish it, distribute the URL, and you're publishing within the flashcard community. So I want to come up with the most efficient technical solutions in order to compensate for the lack of database, lack of unique ids, etc. For those who have designed or developed similar non-traditional, distributed database projects like this, what advice, experience or best-practice tips you can share on the above two points?

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How do I create a partial function with generics in scala?

- by Matteo Caprari

Hello. I'm trying to write a performance measurements library for Scala. My idea is to transparently 'mark' sections so that the execution time can be collected. Unfortunately I wasn't able to bend the compiler to my will. An admittedly contrived example of what I have in mind: // generate a timing function val myTimer = mkTimer('myTimer) // see how the timing function returns the right type depending on the // type of the function it is passed to it val act = actor { loop { receive { case 'Int => val calc = myTimer { (1 to 100000).sum } val result = calc + 10 // calc must be Int self reply (result) case 'String => val calc = myTimer { (1 to 100000).mkString } val result = calc + " String" // calc must be String self reply (result) } Now, this is the farthest I got: trait Timing { def time[T <: Any](name: Symbol)(op: => T) :T = { val start = System.nanoTime val result = op val elapsed = System.nanoTime - start println(name + ": " + elapsed) result } def mkTimer[T <: Any](name: Symbol) : (() => T) => () => T = { type c = () => T time(name)(_ : c) } } Using the time function directly works and the compiler correctly uses the return type of the anonymous function to type the 'time' function: val bigString = time('timerBigString) { (1 to 100000).mkString("-") } println (bigString) Great as it seems, this pattern has a number of shortcomings: forces the user to reuse the same symbol at each invocation makes it more difficult to do more advanced stuff like predefined project-level timers does not allow the library to initialize once a data structure for 'timerBigString So here it comes mkTimer, that would allow me to partially apply the time function and reuse it. I use mkTimer like this: val myTimer = mkTimer('aTimer) val myString= myTimer { (1 to 100000).mkString("-") } println (myString) But I get a compiler error: error: type mismatch; found : String required: () => Nothing (1 to 100000).mkString("-") I get the same error if I inline the currying: val timerBigString = time('timerBigString) _ val bigString = timerBigString { (1 to 100000).mkString("-") } println (bigString) This works if I do val timerBigString = time('timerBigString) (_: String), but this is not what I want. I'd like to defer typing of the partially applied function until application. I conclude that the compiler is deciding the return type of the partial function when I first create it, chosing "Nothing" because it can't make a better informed choice. So I guess what I'm looking for is a sort of late-binding of the partially applied function. Is there any way to do this? Or maybe is there a completely different path I could follow? Well, thanks for reading this far -teo

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With sqlalchemy how to dynamically bind to database engine on a per-request basis

- by Peter Hansen

I have a Pylons-based web application which connects via Sqlalchemy (v0.5) to a Postgres database. For security, rather than follow the typical pattern of simple web apps (as seen in just about all tutorials), I'm not using a generic Postgres user (e.g. "webapp") but am requiring that users enter their own Postgres userid and password, and am using that to establish the connection. That means we get the full benefit of Postgres security. Complicating things still further, there are two separate databases to connect to. Although they're currently in the same Postgres cluster, they need to be able to move to separate hosts at a later date. We're using sqlalchemy's declarative package, though I can't see that this has any bearing on the matter. Most examples of sqlalchemy show trivial approaches such as setting up the Metadata once, at application startup, with a generic database userid and password, which is used through the web application. This is usually done with Metadata.bind = create_engine(), sometimes even at module-level in the database model files. My question is, how can we defer establishing the connections until the user has logged in, and then (of course) re-use those connections, or re-establish them using the same credentials, for each subsequent request. We have this working -- we think -- but I'm not only not certain of the safety of it, I also think it looks incredibly heavy-weight for the situation. Inside the __call__ method of the BaseController we retrieve the userid and password from the web session, call sqlalchemy create_engine() once for each database, then call a routine which calls Session.bind_mapper() repeatedly, once for each table that may be referenced on each of those connections, even though any given request usually references only one or two tables. It looks something like this: # in lib/base.py on the BaseController class def __call__(self, environ, start_response): # note: web session contains {'username': XXX, 'password': YYY} url1 = 'postgres://%(username)s:%(password)s@server1/finance' % session url2 = 'postgres://%(username)s:%(password)s@server2/staff' % session finance = create_engine(url1) staff = create_engine(url2) db_configure(staff, finance) # see below ... etc # in another file Session = scoped_session(sessionmaker()) def db_configure(staff, finance): s = Session() from db.finance import Employee, Customer, Invoice for c in [ Employee, Customer, Invoice, ]: s.bind_mapper(c, finance) from db.staff import Project, Hour for c in [ Project, Hour, ]: s.bind_mapper(c, staff) s.close() # prevents leaking connections between sessions? So the create_engine() calls occur on every request... I can see that being needed, and the Connection Pool probably caches them and does things sensibly. But calling Session.bind_mapper() once for each table, on every request? Seems like there has to be a better way. Obviously, since a desire for strong security underlies all this, we don't want any chance that a connection established for a high-security user will inadvertently be used in a later request by a low-security user.

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redoing object model construction to fit with asynchronous data fetching

- by Andrew Patterson

I have a modeled a set of objects that correspond with some real world concepts. TradeDrug, GenericDrug, TradePackage, DrugForm Underlying the simple object model I am trying to provide is a complex medical terminology that uses numeric codes to represent relationships and concepts, all accessible via a REST service - I am trying to hide away some of that complexity with an object wrapper. To give a concrete example I can call TradeDrug d = Searcher.FindTradeDrug("Zoloft") or TradeDrug d = new TradeDrug(34) where 34 might be the code for Zoloft. This will consult a remote server to find out some details about Zoloft. I might then call GenericDrug generic = d.EquivalentGeneric() System.Out.WriteLine(generic.ActiveIngredient().Name) in order to get back the generic drug sertraline as an object (again via a background REST call to the remote server that has all these drug details), and then perhaps find its ingredient. This model works fine and is being used in some applications that involve data processing. Recently however I wanted to do a silverlight application that used and displayed these objects. The silverlight environment only allows asynchronous REST/web service calls. I have no problems with how to make the asychhronous calls - but I am having trouble with what the design should be for my object construction. Currently the constructors for my objects do some REST calls sychronously. public TradeDrug(int code) { form = restclient.FetchForm(code) name = restclient.FetchName(code) etc.. } If I have to use async 'events' or 'actions' in order to use the Silverlight web client (I know silverlight can be forced to be a synchronous client but I am interested in asychronous approaches), does anyone have an guidance or best practice for how to structure my objects. I can pass in an action callback to the constructor public TradeDrug(int code, Action<TradeDrug> constructCompleted) { } but this then allows the user to have a TradeDrug object instance before what I want to construct is actually finished. It also doesn't support an 'event' async pattern because the object doesn't exist to add the event to until it is constructed. Extending that approach might be a factory object that itself has an asynchronous interface to objects factory.GetTradeDrugAsync(code, completedaction) or with a GetTradeDrugCompleted event? Does anyone have any recommendations?

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Register all GUI components as Observers or pass current object to next object as a constructor argu

- by Jack

First, I'd like to say that I think this is a common issue and there may be a simple or common solution that I am unaware of. Many have probably encountered a similar problem. Thanks for reading. I am creating a GUI where each component needs to communicate (or at least be updated) by multiple other components. Currently, I'm using a Singleton class to accomplish this goal. Each GUI component gets the instance of the singleton and registers itself. When updates need to be made, the singleton can call public methods in the registered class. I think this is similar to an Observer pattern, but the singleton has more control. Currently, the program is set up something like this: class c1 { CommClass cc; c1() { cc = CommClass.getCommClass(); cc.registerC1( this ); C2 c2 = new c2(); } } class c2 { CommClass cc; c2() { cc = CommClass.getCommClass(); cc.registerC2( this ); C3 c3 = new c3(); } } class c3 { CommClass cc; c3() { cc = CommClass.getCommClass(); cc.registerC3( this ); C4 c4 = new c4(); } } etc. Unfortunately, the singleton class keeps growing larger as more communication is required between the components. I was wondering if it's a good idea to instead of using this singleton, pass the higher order GUI components as arguments in the constructors of each GUI component: class c1 { c1() { C2 c2 = new c2( this ); } } class c2 { C1 c1; c2( C1 c1 ) { this.c1 = c1 C3 c3 = new c3( c1, this ); } } class c3 { C1 c1; C2 c2; c3( C1 c1, C2 c2 ) { this.c1 = c1; this.c2 = c2; C4 c4 = new c4( c1, c2, this ); } } etc. The second version relies less on the CommClass, but it's still very messy as the private member variables increase in number and the constructors grow in length. Each class contains GUI components that need to communicate through CommClass, but I can't think of a good way to do it. If this seems strange or horribly inefficient, please describe some method of communication between classes that will continue to work as the project grows. Also, if this doesn't make any sense to anyone, I'll try to give actual code snippets in the future and think of a better way to ask the question. Thanks.

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Fuzzy Regex, Text Processing, Lexical Analysis?

- by justinzane

I'm not quite sure what terminology to search for, so my title is funky... Here is the workflow I've got: Semi-structured documents are scanned to file. The files are OCR'd to text. The text is parsed into Python objects The objects are serialized (to SQL, JSON, whatever) for use. The documents are structures like this: HEADER blah blah, Page ### blah Garbage text... 1. Question Text... continued until now. A. Choice text... adsadsf. B. Another Choice... 2. Another Question... I need to extract the questions and choices. The problem is that, because the text is OCR output, there are occasional strange substitutions like '2' - 'Z' which makes ordinary regular expressions useless. I've tried the Levenshtein module and it helps, but it requires prior knowledge of what edit distance is to be expected. I don't know whether I'm looking to create a parser? a lexer? something else? This has lead me down all kinds of interesting but nonrelevant paths. Guidance would be greatly appreciated. Oh, also, the text is generally from specific technical domains, so general spelling tools are not so helpful. Regarding the structure of the documents, there is no clear visual pattern -- like line breaks or indentation -- with the exception of the fact that "questions" usually begin a line. Crap on the document can cause characters to appear before the actual beginning of the line, which means that something along the lines of r'^[0-9]+' does not reliably work. Though the "questions" always begin with an int, a period and a space; the OCR can substitute other characters or skip characters. This is not so much a problem with Tesseract or Cunieform, rather with the poor quality of the paper documents. # Note: for the project in question, it was decided that having a human prep the OCR'd text was better that spending the time coding a solution. I'd still love good pointers, however.

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How to efficiently save changes made in UI/main thread with Core Data?

- by Jaanus

So, there have been several posts here about importing and saving data from an external data source into Core Data. Apple documents a reasonable pattern for this: "import and save on background thread, merge saved objects to main thread." All fine and good. I have a related but different problem: the user is modifying data in the UI and main thread, and thus modifies state of some objects in the managed object context (MOC). I would like to save these changes from time to time. What is a good way to do that? Now, you could say that I could do the same: create a background thread with its own MOC and pass the changed objectID-s there. The catch-22 for me with this is that an object's ID changes when it is saved, and I cannot guarantee the order of things happening. I may end up passing a different objectID into the background thread for the same object, based on whether the object has been previously saved or not, and I don't know if Core Data can resolve this and see that different objectID-s are pointing to the same object and not create duplicates for me. (I could test this, but I'm lazywebbing with this question first.) One thought I had: I could always do MOC saves on a background thread, and queue them up with operationqueue, so that there is always only one save in progress. I would not create a new MOC, I would just use the same MOC as in main thread. Now, this is not thread safe and when someone modifies the MOC in main thread while it is being saved in background thread, the results will probably be catastrophic. But, minus the thread safety, you can see what kind of solution I'd wish for. To be clear, the problem I need to fix is that if I just do the save in main thread, it blocks the UI for an unacceptably long period of time, I want to move the save to background thread. So, questions: what about the reasoning of an object ID changing during saving, and Core Data being able to resolve them to the same object? Would this be the right way of addressing this problem? any other good ways of doing this?

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C# Chain-of-responsibility with delegates

- by nettguy

For my understanding purpose i have implemented Chain-Of-Responsibility pattern. //Abstract Base Type public abstract class CustomerServiceDesk { protected CustomerServiceDesk _nextHandler; public abstract void ServeCustomers(Customer _customer); public void SetupHadler(CustomerServiceDesk _nextHandler) { this._nextHandler = _nextHandler; } } public class FrontLineServiceDesk:CustomerServiceDesk { public override void ServeCustomers(Customer _customer) { if (_customer.ComplaintType == ComplaintType.General) { Console.WriteLine(_customer.Name + " Complaints are registered ; will be served soon by FrontLine Help Desk.."); } else { Console.WriteLine(_customer.Name + " is redirected to Critical Help Desk"); _nextHandler.ServeCustomers(_customer); } } } public class CriticalIssueServiceDesk:CustomerServiceDesk { public override void ServeCustomers(Customer _customer) { if (_customer.ComplaintType == ComplaintType.Critical) { Console.WriteLine(_customer.Name + "Complaints are registered ; will be served soon by Critical Help Desk"); } else if (_customer.ComplaintType == ComplaintType.Legal) { Console.WriteLine(_customer.Name + "is redirected to Legal Help Desk"); _nextHandler.ServeCustomers(_customer); } } } public class LegalissueServiceDesk :CustomerServiceDesk { public override void ServeCustomers(Customer _customer) { if (_customer.ComplaintType == ComplaintType.Legal) { Console.WriteLine(_customer.Name + "Complaints are registered ; will be served soon by legal help desk"); } } } public class Customer { public string Name { get; set; } public ComplaintType ComplaintType { get; set; } } public enum ComplaintType { General, Critical, Legal } void Main() { CustomerServiceDesk _frontLineDesk = new FrontLineServiceDesk(); CustomerServiceDesk _criticalSupportDesk = new CriticalIssueServiceDesk(); CustomerServiceDesk _legalSupportDesk = new LegalissueServiceDesk(); _frontLineDesk.SetupHadler(_criticalSupportDesk); _criticalSupportDesk.SetupHadler(_legalSupportDesk); Customer _customer1 = new Customer(); _customer1.Name = "Microsoft"; _customer1.ComplaintType = ComplaintType.General; Customer _customer2 = new Customer(); _customer2.Name = "SunSystems"; _customer2.ComplaintType = ComplaintType.Critical; Customer _customer3 = new Customer(); _customer3.Name = "HP"; _customer3.ComplaintType = ComplaintType.Legal; _frontLineDesk.ServeCustomers(_customer1); _frontLineDesk.ServeCustomers(_customer2); _frontLineDesk.ServeCustomers(_customer3); } Question Without breaking the chain-of-responsibility ,how can i apply delegates and events to rewrite the code?

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R Install/Update on Mac OS X (Snow Leopard): where does R put files during install/config?

- by doug

In sum, there's a stray preference-like file or two (probably just one) that i can't find. Here's the whole story: I recently attempted to update my R install from 2.10 to 2.11. As i have done before, i installed from source. I know that all of the dependencies are correctly installed and made available to R, because my prior install worked fine. When i upgraded to 2.11, i am unable to install packages (no exception thrown, it just doesn't appear to complete the install and is unresponsive so i have to quit + restart R. Given i install from source, there are any number of points in the process that i could have messed up. What i need to do now is "start over" which requires that i clear out my my prior install. I am having trouble doing that. There is still at least one preference file or something like that i can't find and one of these is causing the problem, so i need to find it and terminate it with extreme prejudice before i do a fresh install. Although i set a number of flags during the install, i have never opted out of the default install locations during the config step. There has to be one or more preference files still in my file structure (and that's also accessible to the new install of R) because after i follow all of the steps below, then do a fresh install, when i start R for the first time, some of my preferences have persisted (e.g., quartz settings, GUI background color, editor selection, etc.). Again, the problem is that i just cannot locate those files. Finally, the problem can't be that during my last install from source, i inadvertently caused a preference file to be sent to an off-spec location--because again, a fresh R install (whether from source or from the OS X binaries) is finding those files Here's what i've done prior to attempting a clean install of R: Removed files from these locations: ~/.RData ~/.RHistory /Applications/R64.app /Applications/R.app /Library/Frameworks/R.framework (i also removed all symlinks from these) Cleared all RAM and disk caches, in particular the directory where i know R caches: ~/Library/Caches/R* (in fact i've cleared this entire directory) Checked for all 'hidden' files in the OS X directories where login/startup files are often placed: /etc/ ~/ In addition, i've checked R-help, and i've also read through the relevant portions of 'R Installation and Administration'--no luck. I've also searched searched my file structure using the various bash utilities, which nearly always solves problems of this sort quite easily, but in this case obviously searching by name or even pattern is more problematic.

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Deleting items from a ListView using a custom BaseAdapter

- by HXCaine

I am using a customised BaseAdapter to display items on a ListView. The items are just strings held in an ArrayList. The list items have a delete button on them (big red X), and I'd like to remove the item from the ArrayList, and notify the ListView to update itself. However, every implementation I've tried gets mysterious position numbers given to it, so for example clicking item 2's delete button will delete item 5's. It seems to be almost entirely random. One thing to note is that elements may be repeated, but must be kept in the same order. For example, I can have "Irish" twice, as elements 3 and 7. My code is below: private static class ViewHolder { TextView lang; int position; } public View getView(final int position, View convertView, ViewGroup parent) { ViewHolder holder; if (convertView == null) { convertView = mInflater.inflate(R.layout.language_link_row, null); holder = new ViewHolder(); holder.lang = (TextView)convertView.findViewById(R.id.language_link_text); holder.position = position; final ImageView deleteButton = (ImageView) convertView.findViewById(R.id.language_link_cross_delete); deleteButton.setOnClickListener(this); convertView.setTag(holder); deleteButton.setTag(holder); } else { holder = (ViewHolder) convertView.getTag(); } holder.lang.setText(mLanguages.get(position)); return convertView; } I later attempt to retrieve the deleted element's position by grabbing the tag, but it's always the wrong position in the list. There is no noticeable pattern to the position given here, it always seems random. // The delete button's listener public void onClick(View v) { ViewHolder deleteHolder = (ViewHolder) v.getTag(); int pos = deleteHolder.position; ... ... ... } I would be quite happy to just delete the item from the ArrayList and have the ListView update itself, but the position I'm getting is incorrect so I can't do that. Please note that I did, at first, have the deleteButton clickListener inside the getView method, and used 'position' to delete the value, but I had the same problem. Any suggestions appreciated, this is really irritating me.

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How to modularize a JSF/Facelets/Spring application with OSGi?

- by lexicore

I'm working with very large JSF/Facelets applications which use Spring for DI/bean management. My applications have modular structure and I'm currently looking for approaches to standardize the modularization. My goal is to compose a web application from a number of modules (possibly depending on each other). Each module may contain the following: Classes; Static resources (images, CSS, scripts); Facelet templates; Managed beans - Spring application contexts, with request, session and application-scoped beans (alternative is JSF managed beans); Servlet API stuff - servlets, filters, listeners (this is optional). What I'd like to avoid (almost at all costs) is the need to copy or extract module resources (like Facelets templates) to the WAR or to extend the web.xml for module's servlets, filters, etc. It must be enough to add the module (JAR, bundle, artifact, ...) to the web application (WEB-INF/lib, bundles, plugins, ...) to extend the web application with this module. Currently I solve this task with a custom modularization solution which is heavily based on using classpath resources: Special resources servlet serves static resources from classpath resources (JARs). Special Facelets resource resolver allows loading Facelet templates from classpath resources. Spring loads application contexts via the pattern classpath*:com/acme/foo/module/applicationContext.xml - this loads application contexts defined in module JARs. Finally, a pair of delegating servlets and filters delegate request processing to the servlets and filters configured in Spring application contexts from modules. Last days I read a lot about OSGi and I was considering, how (and if) I could use OSGi as a standardized modularization approach. I was thinking about how individual tasks could be solved with OSGi: Static resources - OSGi bundles which want to export static resources register a ResourceLoader instances with the bundle context. A central ResourceServlet uses these resource loaders to load resources from bundles. Facelet templates - similar to above, a central ResourceResolver uses services registered by bundles. Managed beans - I have no idea how to use an expression like #{myBean.property} if myBean is defined in one of the bundles. Servlet API stuff - use something like WebExtender/Pax Web to register servlets, filters and so on. My questions are: Am I inventing a bicycle here? Are there standard solutions for that? I've found a mentioning of Spring Slices but could not find much documentation about it. Do you think OSGi is the right technology for the described task? Is my sketch of OSGI application more or less correct? How should managed beans (especially request/session scope) be handled? I'd be generally graefult for your comments.

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Making a Grid in an NSView

- by Hooligancat

I currently have an NSView that draws a grid pattern (essentially a guide of horizontal and vertical lines) with the idea being that a user can change the spacing of the grid and the color of the grid. The purpose of the grid is to act as a guideline for the user when lining up objects. Everything works just fine with one exception. When I resize the NSWindow by dragging the resize handle, if my grid spacing is particularly small (say 10 pixels). the drag resize becomes lethargic in nature. My drawRect code for the grid is as follows: -(void)drawRect:(NSRect)dirtyRect { NSRect thisViewSize = [self bounds]; // Set the line color [[NSColor colorWithDeviceRed:0 green:(255/255.0) blue:(255/255.0) alpha:1] set]; // Draw the vertical lines first NSBezierPath * verticalLinePath = [NSBezierPath bezierPath]; int gridWidth = thisViewSize.size.width; int gridHeight = thisViewSize.size.height; int i; while (i < gridWidth) { i = i + [self currentSpacing]; NSPoint startPoint = {i,0}; NSPoint endPoint = {i, gridHeight}; [verticalLinePath setLineWidth:1]; [verticalLinePath moveToPoint:startPoint]; [verticalLinePath lineToPoint:endPoint]; [verticalLinePath stroke]; } // Draw the horizontal lines NSBezierPath * horizontalLinePath = [NSBezierPath bezierPath]; i = 0; while (i < gridHeight) { i = i + [self currentSpacing]; NSPoint startPoint = {0,i}; NSPoint endPoint = {gridWidth, i}; [horizontalLinePath setLineWidth:1]; [horizontalLinePath moveToPoint:startPoint]; [horizontalLinePath lineToPoint:endPoint]; [horizontalLinePath stroke]; } } I suspect this is entirely to do with the way that I am drawing the grid and am open to suggestions on how I might better go about it. I can see where the inefficiency is coming in, drag-resizing the NSWindow is constantly calling the drawRect in this view as it resizes, and the closer the grid, the more calculations per pixel drag of the parent window. I was thinking of hiding the view on the resize of the window, but it doesn't feel as dynamic. I want the user experience to be very smooth without any perceived delay or flickering. Does anyone have any ideas on a better or more efficient method to drawing the grid? All help, as always, very much appreciated.

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MemoryStream, XmlTextWriter and Warning 4 CA2202 : Microsoft.Usage

- by rasx

The Run Code Analysis command in Visual Studio 2010 Ultimate returns a warning when seeing a certain pattern with MemoryStream and XmlTextWriter. This is the warning: Warning 7 CA2202 : Microsoft.Usage : Object 'ms' can be disposed more than once in method 'KinteWritePages.GetXPathDocument(DbConnection)'. To avoid generating a System.ObjectDisposedException you should not call Dispose more than one time on an object.: Lines: 421 C:\Visual Studio 2010\Projects\Songhay.DataAccess.KinteWritePages\KinteWritePages.cs 421 Songhay.DataAccess.KinteWritePages This is the form: static XPathDocument GetXPathDocument(DbConnection connection) { XPathDocument xpDoc = null; var ms = new MemoryStream(); try { using(XmlTextWriter writer = new XmlTextWriter(ms, Encoding.UTF8)) { using(DbDataReader reader = CommonReader.GetReader(connection, Resources.KinteRssSql)) { writer.WriteStartDocument(); writer.WriteStartElement("data"); do { while(reader.Read()) { writer.WriteStartElement("item"); for(int i = 0; i < reader.FieldCount; i++) { writer.WriteRaw(String.Format("<{0}>{1}</{0}>", reader.GetName(i), reader[i].ToString())); } writer.WriteFullEndElement(); } } while(reader.NextResult()); writer.WriteFullEndElement(); writer.WriteEndDocument(); writer.Flush(); ms.Position = 0; xpDoc = new XPathDocument(ms); } } } finally { ms.Dispose(); } return xpDoc; } The same kind of warning is produced for this form: XPathDocument xpDoc = null; using(var ms = new MemoryStream()) { using(XmlTextWriter writer = new XmlTextWriter(ms, Encoding.UTF8)) { using(DbDataReader reader = CommonReader.GetReader(connection, Resources.KinteRssSql)) { //... } } } return xpDoc; By the way, the following form produces another warning: XPathDocument xpDoc = null; var ms = new MemoryStream(); using(XmlTextWriter writer = new XmlTextWriter(ms, Encoding.UTF8)) { using(DbDataReader reader = CommonReader.GetReader(connection, Resources.KinteRssSql)) { //... } } return xpDoc; The above produces the warning: Warning 7 CA2000 : Microsoft.Reliability : In method 'KinteWritePages.GetXPathDocument(DbConnection)', object 'ms' is not disposed along all exception paths. Call System.IDisposable.Dispose on object 'ms' before all references to it are out of scope. C:\Visual Studio 2010\Projects\Songhay.DataAccess.KinteWritePages\KinteWritePages.cs 383 Songhay.DataAccess.KinteWritePages In addition to the following, what are my options?: Supress warning CA2202. Supress warning CA2000 and hope that Microsoft is disposing of MemoryStream (because Reflector is not showing me the source code). Rewrite my legacy code to recognize the wonderful XDocument and LINQ to XML.

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Need help with implementation of the jQuery LiveUpdate routine

- by miCRoSCoPiC_eaRthLinG

Hey all, Has anyone worked with the LiveUpdate function (may be a bit of a misnomer) found on this page? It's not really a live search/update function, but a quick filtering mechanism for a pre-existing list, based on the pattern you enter in a text field. For easier reference, I'm pasting the entire function in here: jQuery.fn.liveUpdate = function(list){ list = jQuery(list); if ( list.length ) { var rows = list.children('li'), cache = rows.map(function(){ return this.innerHTML.toLowerCase(); }); this .keyup(filter).keyup() .parents('form').submit(function(){ return false; }); } return this; function filter(){ var term = jQuery.trim( jQuery(this).val().toLowerCase() ), scores = []; if ( !term ) { rows.show(); } else { rows.hide(); cache.each(function(i){ var score = this.score(term); if (score > 0) { scores.push([score, i]); } }); jQuery.each(scores.sort(function(a, b){return b[0] - a[0];}), function(){ jQuery(rows[ this[1] ]).show(); }); } } }; I have this list, with members as the ID. And a text field with say, qs as ID. I tried binding the function in the following manner: $( '#qs' ).liveUpdate( '#members' ); But when I do this, the function is called only ONCE when the page is loaded (I put in some console.logs in the function) but never after when text is keyed into the text field. I also tried calling the routine from the keyup() function of qs. $( '#qs' ).keyup( function() { $( this ).liveUpdate( '#members' ); }); This ends up going into infinite loops (almost) and halting with "Too much recursion" errors. So can anyone please shed some light on how I am supposed to actually implement this function? Also while you are at it, can someone kindly explain this line to me: var score = this.score(term); What I want to know is where this member method score() is coming from? I didn't find any such method built into JS or jQuery. Thanks for all the help, m^e

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WCF Duplex Interaction with Web Server

- by Mark Struzinski

Here is my scenario, and it is causing us a considerable amount of grief at the moment: We have a vendor web service which provides base level telephony functionality. This service has a SOAP api, which we are leveraging to build up a custom UI that is integrated into our in house web apps. The api functions on 2 levels. You make standard client calls into the service to initiate actions, such as Login, Place Call, Hang Up, etc. On a different thread, the service sends events back to the client to alert the user of things that are occurring on the system (agent successfully logged in, call was disconnected, etc). I implemented a WCF service to sit between the web server and the vendor service. This WCF service operates in duplex mode, establishing a 2 way connection with the web server. The web server makes outbound calls to the WCF service, which routes them to the vendor's web service. Events are received back to the WCF service, which passes them onto the web server via a callback channel on the WCF client. As events are received on the web server, they are placed into a hash table with the user's name as the key, and a .NET queue as the value to hold the event. Each event is enqueued to the agent who owns it. On a 2 second interval, the web page polls the web server via an ajax request to get new events for the logged in user. It hits the hash table for the user key, dequeues any events that are present, and serializes them back up to the web page. From there, they are processed in order and appropriate messages are displayed to the user. This implementation performs well in a single user scenario. The second I put more than 1 user on the system, I start getting frequent timeouts with the following CommunicationException: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond We are running Windows Server 2008 R2 both servers. Both the web app and WCF service are running on .NET 3.5. The WCF service is running under the net.tcp protocol in duplex mode. The web app is ASP.NET MVC 2. Has anyone dealt with anything like this scenario? Is there a more efficient way (or a widely accepted pattern) to implement this?

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