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• How OpenStack Swift handles concurrent restful API request?

  - by Chen Xie

  I installed a swift service and was trying to know the capability of handling concurrent request. So I created massive amount of threads in Java, and sent it via the RestFUL API Not surprisingly, when the number of requests climb up, the program started to throw out exceptions. Caused by: java.net.ConnectException: Connection timed out: connect at java.net.DualStackPlainSocketImpl.connect0(Native Method) at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:69) at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339) at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200) at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:157) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:391) at java.net.Socket.connect(Socket.java:579) at java.net.Socket.connect(Socket.java:528) at sun.net.NetworkClient.doConnect(NetworkClient.java:180) at sun.net.www.http.HttpClient.openServer(HttpClient.java:378) at sun.net.www.http.HttpClient.openServer(HttpClient.java:473) at sun.net.www.http.HttpClient.(HttpClient.java:203) But can anyone tell me how that time outhappened? I am curious of how SWIFT handles those requests. Is that by queuing the requests and because there are too many requests in the queue and wait for too long time and it's just get kicked out from the queue? If this holds, does it mean that it's an asynchronized mechanism to handle requests? Thanks.

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• LINQ to Sql: Insert instead of Update

  - by Christina Mayers

  I am stuck with this problems for a long time now. Everything I try to do is insert a row in my DB if it's new information - if not update the existing one. I've updated many entities in my life before - but what's wrong with this code is beyond me (probably something pretty basic) I guess I can't see the wood for the trees... private Models.databaseDataContext db = new Models.databaseDataContext(); internal void StoreInformations(IEnumerable<EntityType> iEnumerable) { foreach (EntityType item in iEnumerable) { EntityType type = db.EntityType.Where(t => t.Room == item.Room).FirstOrDefault(); if (type == null) { db.EntityType.InsertOnSubmit(item); } else { type.Date = item.Date; type.LastUpdate = DateTime.Now(); type.End = item.End; } } } internal void Save() { db.SubmitChanges(); } Edit: just checked the ChangeSet, there are no updates only inserts. For now I've settled with foreach (EntityType item in iEnumerable) { EntityType type = db.EntityType.Where(t => t.Room == item.Room).FirstOrDefault(); if (type != null) { db.Exams.DeleteOnSubmit(type); } db.EntityType.InsertOnSubmit(item); } but I'd love to do updates and lose these unnecessary delete statements.

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• EC2 persistence of machine

  - by Seagull

  I want to 'persist' my Amazon EC2 images. My scenario: I have a range of Windows and Linux machines Some machines are EBS backed, whereas others are S3 backed. I need to be able to persist a machine (put it to sleep), preferably keeping all settings active I had them when the machine was running. I need to be able to quickly wake up a machine from sleep [Ideally with an SLA of less than 2 min to turn-on, if such an SLA is available with Amazon]. Here's the stuff that confuses me: AWS allows me to put EBS backed machines to sleep, but not S3 backed. I believe I can put S3 machines into some sort of persistence mode. But this involves shutting down the machine, writing it to S3 storage and then recovering from there (not a real sleep mode, but at least I don't continue to get billed for CPU). S3 backing seems to take a long time to either writing a machine to disk, or to recover (turn on a machine). I can't tell immediately which machines are EBS backed and which are S3 backed? It seems like I can instantiate either type, but it's not immediately clear how Amazon decided whether a given machine should be EBS or S3 backed. Advice?

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• How to benchmark on multi-core processors

  - by Pascal Cuoq

  I am looking for ways to perform micro-benchmarks on multi-core processors. Context: At about the same time desktop processors introduced out-of-order execution that made performance hard to predict, they, perhaps not coincidentally, also introduced special instructions to get very precise timings. Example of these instructions are rdtsc on x86 and rftb on PowerPC. These instructions gave timings that were more precise than could ever be allowed by a system call, allowed programmers to micro-benchmark their hearts out, for better or for worse. On a yet more modern processor with several cores, some of which sleep some of the time, the counters are not synchronized between cores. We are told that rdtsc is no longer safe to use for benchmarking, but I must have been dozing off when we were explained the alternative solutions. Question: Some systems may save and restore the performance counter and provide an API call to read the proper sum. If you know what this call is for any operating system, please let us know in an answer. Some systems may allow to turn off cores, leaving only one running. I know Mac OS X Leopard does when the right Preference Pane is installed from the Developers Tools. Do you think that this make rdtsc safe to use again? More context: Please assume I know what I am doing when trying to do a micro-benchmark. If you are of the opinion that if an optimization's gains cannot be measured by timing the whole application, it's not worth optimizing, I agree with you, but I cannot time the whole application until the alternative data structure is finished, which will take a long time. In fact, if the micro-benchmark were not promising, I could decide to give up on the implementation now; I need figures to provide in a publication whose deadline I have no control over.

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• JavaScript onchange, onblur, and focus weirdness in Firefox

  - by typoknig

  On my form I have a discount field that accepts a dollar amount to be taken off of the total bill (HTML generated in PHP): echo "<input id=\"discount\" class=\"text\" type=\"text\" name=\"discount\" onkeypress=\"return currency(this, event)\" onchange=\"currency_format(this)\" onfocus=\"on_focus(this)\" onblur=\"on_blur(this); calculate_bill()\"/><br/><br/>\n"; The JavaScript function calculate_bill calculates the bill and takes off the discount amount as long as the discount amount is less than the total bill: if(discount != ''){ if(discount - 0.01 > total_bill){ window.alert('Discount Cannot Be Greater Than Total Bill'); document.form.discount.focus(); } else{ total_bill -= discount; } } The problem is that even that when the discount is more than the total bill focus is not being returned to the discount field. I have tried calling the calculate_bill function with onchange but neither IE or Firefox will return focus to the discount field when I do it like that. When I call calculate_bill with onblur it works in IE, but still does not work in Firefox. I have attempted to use a confirmation box instead of an alert box as well, but that didn't work either (plus I don't want two buttons, I only an "OK" button). How can I ensure focus is returned to the discount field after a user has left that field by clicking on another field or tabbing IF the discount amount is larger than the total bill?

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• program won't find math.h anymore

  - by 130490868091234

  After a long time, I downloaded a program I co-developed and tried to recompile it on my Ubuntu Linux 12.04, but it seems it does not find math.h anymore. This may be because something has changed recently in gcc, but I can't figure out if it's something wrong in src/Makefile.am or a missing dependency: Download from http://www.ub.edu/softevol/variscan/: tar xzf variscan-2.0.2.tar.gz cd variscan-2.0.2/ make distclean sh ./autogen.sh make I get: [...] gcc -DNDEBUG -O3 -W -Wall -ansi -pedantic -lm -o variscan variscan.o statistics.o common.o linefile.o memalloc.o dlist.o errabort.o dystring.o intExp.o kxTok.o pop.o window.o free.o output.o readphylip.o readaxt.o readmga.o readmaf.o readhapmap.o readxmfa.o readmav.o ran1.o swcolumn.o swnet.o swpoly.o swref.o statistics.o: In function `calculate_Fu_and_Li_D': statistics.c:(.text+0x497): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_and_Li_F': statistics.c:(.text+0x569): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_and_Li_D_star': statistics.c:(.text+0x63b): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_and_Li_F_star': statistics.c:(.text+0x75c): undefined reference to `sqrt' statistics.o: In function `calculate_Tajima_D': statistics.c:(.text+0x85d): undefined reference to `sqrt' statistics.o:statistics.c:(.text+0xcb1): more undefined references to `sqrt' follow statistics.o: In function `calcRunMode21Stats': statistics.c:(.text+0xe02): undefined reference to `log' statistics.o: In function `correctedDivergence': statistics.c:(.text+0xe5a): undefined reference to `log' statistics.o: In function `calcRunMode22Stats': statistics.c:(.text+0x104a): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_fs': statistics.c:(.text+0x11a8): undefined reference to `fabsl' statistics.c:(.text+0x11ca): undefined reference to `powl' statistics.c:(.text+0x11f2): undefined reference to `logl' statistics.o: In function `calculateStatistics': statistics.c:(.text+0x13f2): undefined reference to `log' collect2: ld returned 1 exit status make[1]: *** [variscan] Error 1 make[1]: Leaving directory `/home/avilella/variscan/latest/variscan-2.0.2/src' make: *** [all-recursive] Error 1 The libraries are there because this simple example works perfectly well: $ gcc test.c -o test -lm $ cat test.c #include <stdio.h> #include <math.h> int main(void) { double x = 0.5; double result = sqrt(x); printf("The hyperbolic cosine of %lf is %lf\n", x, result); return 0; } Any ideas?

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• JBoss Clustered Service that sends emails from txt file

  - by michael lucas

  I need a little push in the right direction. Here's my problem: I have to create an ultra-reliable service that sends email messages to clients whose addresses are stored in txt file on FTP server. Single txt file may contain unlimited number of entries. Most often the file contains about 300,000 entries. Service exposes interface with just two simple methods: TaskHandle sendEmails(String ftpFilePath); ProcessStatus checkProcessStatus(TaskHandle taskHandle); Method sendEmails() returns TaskHandle by which we can ask for ProcessStatus. For such a service to be reliable clustering is necessary. Processing single txt file might take a long time. Restarting one node in a cluster should have no impact on sending emails. We use JBoss AS 4.2.0 which comes with a nice HASingletonController that ensure one instance of service is running at given time. But once a fail-over happens, the second service should continue work from where the first one stopped. How can I share state between nodes in a cluster in such a way that leaves no possibility of sending some emails twice?

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• Linux time sample based profiler.

  - by Caspin

  short version: Is there a good time based sampling profiler for Linux? long version: I generally use OProfile to optimize my applications. I recently found a shortcoming that has me wondering. The problem was a tight loop spawning c++filt to demangle a c++ name. I only stumbled upon the code by accident while chasing down another bottleneck. The OProfile didn't show anything unusual about the code so I almost ignored it but my code sense told me to optimize the call and see what happened. I changed the popen of c++filt to abi::__cxa_demangle. The runtime went from more than a minute to a little over a second. About a x60 speed up. Is there a way I could have configured OProfile to flag the popen call? As the profile data sits now OProfile thinks the bottle neck was the heap and std::string calls (which BTW once optimized dropped the runtime to less than a second, more than x2 speed up). Here is my OProfile configuration: $ sudo opcontrol --status Daemon not running Event 0: CPU_CLK_UNHALTED:90000:0:1:1 Separate options: library vmlinux file: none Image filter: /path/to/excutable Call-graph depth: 7 Buffer size: 65536 Is there another profiler for Linux that could have found the bottleneck? I suspect the issue is that OProfile only logs its samples to the currently running process. I'd like it to always log its samples to the process I'm profiling. So if the process is currently switched out (blocking on IO or a popen call) OProfile would just place its sample at the blocked call. If I can't fix this, OProfile will only be useful when the executable is pushing near 100% CPU. It can't help with executables that that have inefficient blocking calls.

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• Two column layout, navigation div on the right, solution from previous thread didn't seem to work

  - by Tom

  I tried the solution from this thread, but I must be missing something because it doesn't work: <div style="float:left;margin-right:200px"> <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p> </div> <div style="float:right;width:200px"> <p>navigation</p> </div> It works when the text in the content div (the left one) is short, but when it's long then the div takes up the whole width of the browser and the margin is there, but the right div is pushed below the first one nevertheless. What am I missing? Edit: The goal is to have a fix sized navigation column on the right of the browser window and the left div should get all the space left by the right navigation column (liquid layout).

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• How can you transform a set of numbers into mostly whole ones?

  - by Alice

  Small amount of background: I am working on a converter that bridges between a map maker (Tiled) that outputs in XML, and an engine (Angel2D) that inputs lua tables. Most of this is straight forward However, Tiled outputs in pixel offsets (integers of absolute values), while Angel2D inputs OpenGL units (floats of relative values); a conversion factor between these two is needed (for example, 32px = 1gu). Since OpenGL units are abstract, and the camera can zoom in or out if the objects are too small or big, the actual conversion factor isn't important; I could use a random number, and the user would merely have to zoom in or out. But it would be best if the conversion factor was selected such that most numbers outputted were small and whole (or fractions of small whole numbers), because that makes it easier to work with (and the whole point of the OpenGL units is that they are easy to work with). How would I find such a conversion factor reliably? My first attempt was to use the smallest number given; this resulted in no fractions below 1, but often lead to lots of decimal places where the factors didn't line up. Then I tried the mode of the sequence, which lead to the largest number of 1's possible, but often lead to very long floats for background images. My current approach gets the GCD of the whole sequence, which, when it works, works great, but can easily be thrown off course by a single bad apple. Note that while I could easily just pass the numbers I am given along, or pick some fixed factor, or use one of the conversions I specified above, I am looking for a method to reliably scale this list of integers to small, whole numbers or simple fractions, because this would most likely be unsurprising to the end user; this is not a one off conversion. The end users tend to use 1.0 as their "base" for manipulations (because it's simple and obvious), so it would make more sense for the sizes of entities to cluster around this.

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• Using SVN post-commit hook to update only files that have been commited

  - by fondie

  I am using an SVN repository for my web development work. I have a development site set up which holds a checkout of the repository. I have set up an SVN post-commit hook so that whenever a commit is made to the repository the development site is updated: cd /home/www/dev_ssl /usr/bin/svn up This works fine but due to the size of the repository the updates take a long time (approx. 3 minutes) which is rather frustrating when making regular commits. What I'd like is to change the post-commit hook to only update those files/directories that have been committed but I don't know how to go about doing this. Updating the "lowest common directory" would probably be the best solution, e.g. If committing the follow files: /branches/feature_x/images/logo.jpg /branches/feature_x/css/screen.css It would update the directory: /branches/feature_x/ Can anyone help me create a solution that achieves this please? Thanks! Update: The repository and development site are located on the same server so network issues shouldn't be involved. CPU usage is very low, and I/O should be ok (it's running on hi-spec dedicated server) The development site is approx. 7.5GB in size and contains approx. 600,000 items, this is mainly due to having multiple branches/tags

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• MouseMotion Sensor Method Call

  - by user321894

  I have a soon-to-be due assignment due in computer science. I have encountered a problem, for which no matter how long I study the API's of the class and superclasses, I can not figure out. Suppose I wish to design a sort of "Breakout game" where the mouse motion controls the motion of a block that is used to bounce a ball, which then destroys multi colored bricks. How do you specifically make the block "listen" to the mouse? The below code is what I have attempted to achieve the desired results. /** Breakout Program*/ public class Breakout extends GraphicsProgram implements MouseMotionListener { ... /** The Paddle Itself */ private GRect paddle = new GRect(0, HEIGHT-PADDLEBOTTOM_OFFSET, PADDLEWIDTH, PADDLEHEIGHT); ... /** Run the Breakout program. */ public void run() { paddle.setFillColor(Color.BLACK); paddle.setFilled(true); add(paddle); paddle.addMouseListener(this); ... } /** Move the horizontal middle of the paddle to the x-coordinate of the mouse position - * -but keep the paddle completely on the board. */ public void mouseMoved(MouseEvent e) { GPoint p= new GPoint(e.getPoint()); double x = p.getX(); paddle.setLocation(x, HEIGHT-PADDLEBOTTOM_OFFSET); } } Any clarification on why/what I am doing incorrectly would be helpful, thanks.

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• sorting a timer in matlab

  - by AP

  ok it seems like a simple problem, but i am having problem I have a timer for each data set which resets improperly and as a result my timing gets mixed. Any ideas to correct it? without losing any data. Example timer col ideally should be timer , mine reads 1 3 2 4 3 5 4 6 5 1 6 2 how do i change the colum 2 or make a new colum which reads like colum 1 without changing the order of ther rows which have data this is just a example as my file lengths are 86000 long , also i have missing timers which i do not want to miss , this imples no data for that period of time. thanks EDIT: I do not want to change the other columns. The coulm 1 is the gps counter and so it does not sync with the comp timer due to some other issues. I just want to change the row one such that it goes from high to low without effecting other rows. also take care of missing pts ( if i did not care for missing pts simple n=1: max would work.

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• How to calculate the height of the text rectangle from an NSString?

  - by mystify

  I know there is this one: sizeWithFont:minFontSize:actualFontSize:forWidth:lineBreakMode: But since the CGSize always has the same height and doesn't adjust to any shrinked text or whatsoever, the CGSize is not telling how heigh the text is. Example: Make a UILabel with 320 x 55 points and put a loooooooooooooong text in there. Let the label shrink the text down. Surprise: CGSize.height remains the same height even if the text is so tiny that you need a microscope. Ok so after banging my head against my macbook pro which is half way broken now, the only think that can help is that nasty actualFontSize. But the font size is in pica I think, it's not really what you get on the screen, isn't it? When that font size is 10, is my text really 10 points heigh at maximum? Once in a while I tried exactly that, and as soon as the text had a y or some character that extends to below (like that tail of an y does), it is out of bounds and the whole text is bigger than 10 points. So how would you calculate the real text height for a single line uilabel without getting a long beard and some hospital experience?

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• How to query MySQL for exact length and exact UTF-8 characters

  - by oskarae

  I have table with words dictionary in my language (latvian). CREATE TABLE words ( value varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; And let's say it has 3 words inside: INSERT INTO words (value) VALUES ('teja'); INSERT INTO words (value) VALUES ('vejš'); INSERT INTO words (value) VALUES ('feja'); What I want to do is I want to find all words that is exactly 4 characters long and where second character is 'e' and third character is 'j' For me it feels that correct query would be: SELECT * FROM words WHERE value LIKE '_ej_'; But problem with this query is that it returs not 2 entries ('teja','vejš') but all three. As I understand it is because internally MySQL converts strings to some ASCII representation? Then there is BINARY addition possible for LIKE SELECT * FROM words WHERE value LIKE BINARY '_ej_'; But this also does not return 2 entries ('teja','vejš') but only one ('teja'). I believe this has something to do with UTF-8 2 bytes for non ASCII chars? So question: What MySQL query would return my exact two words ('teja','vejš')? Thank you in advance

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• How do I get rid of these warnings?

  - by Brian Postow

  This is really several questions, but anyway... I'm working with a big project in XCode, relatively recently ported from MetroWorks (Yes, really) and there's a bunch of warnings that I want to get rid of. Every so often an IMPORTANT warning comes up, but I never look at them because there's too many garbage ones. So, if I can either figure out how to get XCode to stop giving the warning, or actually fix the problem, that would be great. Here are the warnings: It claims that <map.h> is antiquated. However, when I replace it with <map> my files don't compile. Evidently, there's something in map.h that isn't in map... this decimal constant is unsigned only in ISO C90 This is a large number being compared to an unsigned long. I have even cast it, with no effect. enumeral mismatch in conditional expression: <anonymous enum> vs <anonymous enum> This appears to be from a ?: operator. Possibly that the then and else branches don't evaluate to the same type? Except that in at least one case, it's (matchVp == NULL ? noErr : dupFNErr) And since those are both of type OSErr, which is mac defined... I'm not sure what's up. It also seems to come up when I have other pairs of mac constants... multi-character character constant This one is obvious. The problem is that I actually NEED multi-character constants... -fwritable-strings not compatible with literal CF/NSString I unchecked the "Strings are Read-Only" box in both the project and target settings... and it seems to have had no effect...

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• Application.ProcessMessages hangs???

  - by X-Ray

  my single threaded delphi 2009 app (not quite yet complete) has started to have a problem with Application.ProcessMessages hanging. my app has a TTimer object that fires every 100 ms to poll an external device. i use Application.ProcessMessages to update the screen when something changes so the app is still responsive. one of these was in a grid OnMouseDown event. in there, it had an Application.ProcessMessages that essentially hung. removing that was no problem except that i soon discovered another Application.ProcessMessages that was also blocking. i think what may be happening to me is that the TTimer is--in the app mode i'm currently debugging--probably taking too long to complete. i have prevented the TTimer.OnTimer event hander from re-entering the same code (see below): procedure TfrmMeas.tmrCheckTimer(Sender: TObject); begin if m_CheckTimerBusy then exit; m_CheckTimerBusy:=true; try PollForAndShowMeasurements; finally m_CheckTimerBusy:=false; end; end; what places would it be a bad practice to call Application.ProcessMessages? OnPaint routines springs to mind as something that wouldn't make sense. any general recommendations? i am surprised to see this kind of problem arise at this point in the development!

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• Is there a faster way to parse through a large file with regex quickly?

  - by Ray Eatmon

  Problem: Very very, large file I need to parse line by line to get 3 values from each line. Everything works but it takes a long time to parse through the whole file. Is it possible to do this within seconds? Typical time its taking is between 1 minute and 2 minutes. Example file size is 148,208KB I am using regex to parse through every line: Here is my c# code: private static void ReadTheLines(int max, Responder rp, string inputFile) { List<int> rate = new List<int>(); double counter = 1; try { using (var sr = new StreamReader(inputFile, Encoding.UTF8, true, 1024)) { string line; Console.WriteLine("Reading...."); while ((line = sr.ReadLine()) != null) { if (counter <= max) { counter++; rate = rp.GetRateLine(line); } else if(max == 0) { counter++; rate = rp.GetRateLine(line); } } rp.GetRate(rate); Console.ReadLine(); } } catch (Exception e) { Console.WriteLine("The file could not be read:"); Console.WriteLine(e.Message); } } Here is my regex: public List<int> GetRateLine(string justALine) { const string reg = @"^\d{1,}.+\[(.*)\s[\-]\d{1,}].+GET.*HTTP.*\d{3}[\s](\d{1,})[\s](\d{1,})$"; Match match = Regex.Match(justALine, reg, RegexOptions.IgnoreCase); // Here we check the Match instance. if (match.Success) { // Finally, we get the Group value and display it. string theRate = match.Groups[3].Value; Ratestorage.Add(Convert.ToInt32(theRate)); } else { Ratestorage.Add(0); } return Ratestorage; } Here is an example line to parse, usually around 200,000 lines: 10.10.10.10 - - [27/Nov/2002:16:46:20 -0500] "GET /solr/ HTTP/1.1" 200 4926 789

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• Prevent TEXTAREAs scroll by themselves on IE8

  - by Justin Grant

  IE8 has a known bug (per connect.microsoft.com) where typing or pasting text into a TEXTAREA element will cause the textarea to scroll by itself. This is hugely annoying and shows up in many community sites, including Wikipedia. The repro is this: open the HTML below with IE8 (or use any long page on wikipedia which will exhibit the same problem until they fix it) size the browser full-screen paste a few pages of text into the TEXTAREA move the scrollbar to the middle position now type one character into the textarea Expected: nothing happens Actual: scrossing happens on its own, and the insertion point ends up near the bottom of the textarea! Below is repro HTML (can also see this live on the web here: http://en.wikipedia.org/w/index.php?title=Text_box&action=edit) <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <body> <div style="width: 80%"> <textarea rows="20" cols="80" style="width:100%;" ></textarea> </div> </body> </html>

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• Transitioning from desktop app written in C++ to a web-based app

  - by Karim

  We have a mature Windows desktop application written in C++. The application's GUI sits on top of a windows DLL that does most of the work for the GUI (it's kind of the engine). It, too, is written in C++. We are considering transitioning the Windows app to be a web-based app for various reasons. What I would like to avoid is having to writing the CGI for this web-based app in C++. That is, I would rather have the power of a 4G language like Python or a .NET language for creating the web-based version of this app. So, the question is: given that I need to use a C++ DLL on the backend to do the work of the app what technology stack would you recommend for sitting between the user's browser and are C++ dll? We can assume that the web server will be Windows. Some options: Write a COM layer on top of the windows DLL which can then be access via .NET and use ASP.NET for the UI Access the export DLL interface directly from .NET and use ASP.NET for the UI. Write a custom Python library that wraps the windows DLL so that the rest of the code can be written. Write the CGI using C++ and a C++-based MVC framework like Wt Concerns: I would rather not use C++ for the web framework if it can be avoided - I think languages like Python and C# are simply more powerful and efficient in terms of development time. I'm concerned that my mixing managed and unmanaged code with one of the .NET solutions I'm asking for lots of little problems that are hard to debug (purely anecdotal evidence for that) Same is true for using a Python layer. Anything that's slightly off the beaten path like that worries me in that I don't have much evidence one way or the other if this is a viable long term solution.

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• Adding web reference on client when using Net.TCP

  - by Marko

  Hi everyone... I am trying to using Net.TCP in my WCF Service, which is self hosted, when i try to add this service reference through web reference to my client, i am not able access the classes and methods of that service, can any have any idea to achieve this... How I can add web references in this case. My Service has one method (GetNumber) that returns int. WebService: public class WebService : IWebService { public int GetNumber(int num) { return num + 1; } } Service Contract code: [ServiceContract] public interface IWebService { [OperationContract] int GetNumber(int num); } WCF Service code: ServiceHost host = new ServiceHost(typeof(WebService)); host.AddServiceEndpoint(typeof(IWebService), new NetTcpBinding(), new Uri("net.tcp://" + Dns.GetHostName() + ":1255/WebService")); NetTcpBinding binding = new NetTcpBinding(); binding.TransferMode = TransferMode.Streamed; binding.ReceiveTimeout = TimeSpan.MaxValue; binding.MaxReceivedMessageSize = long.MaxValue; Console.WriteLine("{0}", Dns.GetHostName().ToString()); Console.WriteLine("Opening Web Service..."); host.Open(); Console.WriteLine("Web Service is running on port {0}",1255); Console.WriteLine("Press <ENTER> to EXIT"); Console.ReadLine(); This works fine. Only problem is how to add references of this service in my client application. I just want to send number and to receive an answer. Can anyone help me?

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• Memory Profiling with DotTrace Questions

  - by cam

  I ran dotTrace on my application (which is having some issues). IntPtr System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr, IntPtr, Int32, IntPtr, IntPtr) Void System.Windows.Forms.UnsafeNativeMethods.WaitMessage() Are the two main functions that came up, taking about 94% of the application time. Since I didn't know what these two functions were, I ran through my code line by line. It runs smooth and efficiently until a point where it just hangs. "newFrm.Show()". The newFrm only contains a textbox. The larger the file I load into the text box (it's a notepad program), the longer it takes. Now normally this makes sense, but it takes about 30 seconds for a 167 kB file. Now I'm not sure what to do. It runs incredibly slow/stops functioning when you load a textfile and try to resize the window containing the text file too. Then I realized that it is only struggling to open text files with a long string of hex inside (ie) "XX-XX-XX-" etc. With other similarly sized files it struggles with resizing somewhat, but opens within a couple seconds. Does this have something to do with the textbox properties? I've set it to multiline and set maximum characters to 0 (so unlimited). How do I solve this issue? Is there some way I can see what is being called in those functions?

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• Simple Database normalization question...

  - by user365531

  Hi all, I have a quick question regarding a database that I am designing and making sure it is normalized... I have a customer table, with a primary key of customerId. It has a StatusCode column that has a code which reflects the customers account status ie. 1 = Open, 2 = Closed, 3 = Suspended etc... Now I would like to have another field in the customer table that flags whether the account is allowed to be suspended or not... certain customers will be automatically suspended if they break there trading terms... others not... so the relevant table fields will be as so: Customers (CustomerId(PK):StatusCode:IsSuspensionAllowed) Now both fields are dependent on the primary key as you can not determine the status or whether suspensions are allowed on a particular customer unless you know the specific customer, except of course when the IsSuspensionAllowed field is set to YES, the the customer should never have a StatusCode of 3 (Suspended). It seems from the above table design it is possible for this to happen unless a check contraint is added to my table. I can't see how another table could be added to the relational design to enforce this though as it's only in the case where IsSuspensionAllowed is set to YES and StatusCode is set to 3 when the two have a dependence on each other. So after my long winded explanation my question is this: Is this a normalization problem and I'm not seeing a relational design that will enforce this... or is it actually just a business rule that should be enforced with a check contraint and the table is in fact still normalized. Cheers, Steve

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• How to approach parallel processing of messages?

  - by Dan

  I am redesigning the messaging system for my app to use intel threading building blocks and am stumped trying to decide between two possible approaches. Basically, I have a sequence of message objects and for each message type, a sequence of handlers. For each message object, I apply each handler registered for that message objects type. The sequential version would be something like this (pseudocode): for each message in message_sequence <- SEQUENTIAL for each handler in (handler_table for message.type) apply handler to message <- SEQUENTIAL The first approach which I am considering processes the message objects in turn (sequentially) and applies the handlers concurrently. Pros: predictable ordering of messages (ie, we are guaranteed a FIFO processing order) (potentially) lower latency of processing each message Cons: more processing resources available than handlers for a single message type (bad parallelization) bad use of processor cache since message objects need to be copied for each handler to use large overhead for small handlers The pseudocode of this approach would be as follows: for each message in message_sequence <- SEQUENTIAL parallel_for each handler in (handler_table for message.type) apply handler to message <- PARALLEL The second approach is to process the messages in parallel and apply the handlers to each message sequentially. Pros: better use of processor cache (keeps the message object local to all handlers which will use it) small handlers don't impose as much overhead (as long as there are other handlers also to be run) more messages are expected than there are handlers, so the potential for parallelism is greater Cons: Unpredictable ordering - if message A is sent before message B, they may both be processed at the same time, or B may finish processing before all of A's handlers are finished (order is non-deterministic) The pseudocode is as follows: parallel_for each message in message_sequence <- PARALLEL for each handler in (handler_table for message.type) apply handler to message <- SEQUENTIAL The second approach has more advantages than the first, but non-deterministic ordering is a big disadvantage.. Which approach would you choose and why? Are there any other approaches I should consider (besides the obvious third approach: parallel messages and parallel handlers, which has the disadvantages of both and no real redeeming factors as far as I can tell)? Thanks!

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• VSC++, virtual method at bad adress, curious bug

  - by antoon.groenewoud

  Hello, This guy: virtual phTreeClass* GetTreeClass() const { return (phTreeClass*)m_entity_class; } When called, crashed the program with an access violation, even after a full recompile. All member functions and virtual member functions had correct memory adresses (I hovered mouse over the methods in debug mode), but this function had a bad memory adress: 0xfffffffc. Everything looked okay: the 'this' pointer, and everything works fine up until this function call. This function is also pretty old and I didn't change it for a long time. The problem just suddenly popped up after some work, which I commented all out to see what was doing it, without any success. So I removed the virtual, compiled, and it works fine. I add virtual, compiled, and it still works fine! I basically changed nothing, and remember that I did do a full recompile earlier, and still had the error back then. I wasn't able to reproduce the problem. But now it is back. I didn't change anything. Removing virtual fixes the problem. Sincerely, Antoon

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