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• Programming graphics and sound on PC - Total newbie questions, and lots of them!

  - by Russel

  Hello, This isn't exactly specifically a programming question (or is it?) but I was wondering: How are graphics and sound processed from code and output by the PC? My guess for graphics: There is some reserved memory space somewhere that holds exactly enough room for a frame of graphics output for your monitor. IE: 800 x 600, 24 bit color mode == 800x600x3 = ~1.4MB memory space Between each refresh, the program writes video data to this space. This action is completed before the monitor refresh. Assume a simple 2D game: the graphics data is stored in machine code as many bytes representing color values. Depending on what the program(s) being run instruct the PC, the processor reads the appropriate data and writes it to the memory space. When it is time for the monitor to refresh, it reads from each memory space byte-for-byte and activates hardware depending on those values for each color element of each pixel. All of this of course happens crazy-fast, and repeats x times a second, x being the monitor's refresh rate. I've simplified my own likely-incorrect explanation by avoiding talk of double buffering, etc Here are my questions: a) How close is the above guess (the three steps)? b) How could one incorporate graphics in pure C++ code? I assume the practical thing that everyone does is use a graphics library (SDL, OpenGL, etc), but, for example, how do these libraries accomplish what they do? Would manual inclusion of graphics in pure C++ code (say, a 2D spite) involve creating a two-dimensional array of bit values (or three dimensional to include multiple RGB values per pixel)? Is this how it would be done waaay back in the day? c) Also, continuing from above, do libraries such as SDL etc that use bitmaps actual just build the bitmap/etc files into machine code of the executable and use them as though they were build in the same matter mentioned in question b above? d) In my hypothetical step 3 above, is there any registers involved? Like, could you write some byte value to some register to output a single color of one byte on the screen? Or is it purely dedicated memory space (=RAM) + hardware interaction? e) Finally, how is all of this done for sound? (I have no idea :) )

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• What is `objc_msgSend_fixup`, exactly?

  - by Luis Antonio Botelho O. Leite

  I'm messing around with the Objective-C runtime, trying to compile objective-c code without linking it against libobjc, and I'm having some segmentation fault problems with a program, so I generated an assembly file from it. I think it's not necessary to show the whole assembly file. At some point of my main function, I've got the following line (which, by the way, is the line after which I get the seg fault): callq *l_objc_msgSend_fixup_alloc and here is the definition for l_objc_msgSend_fixup_alloc: .hidden l_objc_msgSend_fixup_alloc # @"\01l_objc_msgSend_fixup_alloc" .type l_objc_msgSend_fixup_alloc,@object .section "__DATA, __objc_msgrefs, coalesced","aw",@progbits .weak l_objc_msgSend_fixup_alloc .align 16 l_objc_msgSend_fixup_alloc: .quad objc_msgSend_fixup .quad L_OBJC_METH_VAR_NAME_ .size l_objc_msgSend_fixup_alloc, 16 I've reimplemented objc_msgSend_fixup as a function (id objc_msgSend_fixup(id self, SEL op, ...)) which returns nil (just to see what happens), but this function isn't even being called (the program crashes before calling it). So, my question is, what is callq *l_objc_msgSend_fixup_alloc supposed to do and what is objc_msgSend_fixup (after l_objc_msgSend_fixup_alloc:) supposed to be (a function or an object)? Edit To better explain, I'm not linking my source file against the objc library. What I'm trying to do is implement some parts of the libray, just to see how it works. Here is an approach of what I've done: #include <stdio.h> #include <objc/runtime.h> @interface MyClass { } +(id) alloc; @end @implementation MyClass +(id) alloc { // alloc the object return nil; } @end id objc_msgSend_fixup(id self, SEL op, ...) { printf("Calling objc_msgSend_fixup()...\n"); // looks for the method implementation for SEL in self's vtable return nil; // Since this is just a test, this function doesn't need to do that } int main(int argc, char *argv[]) { MyClass *m; m = [MyClass alloc]; // At this point, according to the assembly code generated // objc_msgSend_fixup should be called. So, the program should, at least, print // "Calling objc_msgSend_fixup()..." on the screen, but it crashes before // objc_msgSend_fixup() is called... return 0; } If the runtime needs to access the object's vtable to find the correct method to call, what is the function which actually does this? I think it is objc_msgSend_fixup, in this case. So, when objc_msgSend_fixup is called, it receives an object as one of its parameters, and, if this object hasn't been initialized, the function fails. So, I've implemented my own version of objc_msgSend_fixup. According to the assembly source above, it should be called. It doesn't matter if the function is actually looking for the implementation of the selector passed as parameter. I just want objc_msgSend_lookup to be called. But, it's not being called, that is, the function that looks for the object's data is not even being called, instead of being called and cause a fault (because it returns a nil (which, by the way, doesn't matter)). The program seg fails before objc_msgSend_lookup is called...

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• Another C datatypes question

  - by b-gen-jack-o-neill

  Hello. Well, I completely get the most basic datatypes of C, like short, int, long, float, to be exact, all numerical types.These types are needed to be known perform right operations with right numbers. For example to use FPU to add two float numbers. So the compiler must know what the type is. But, when it comes to characters I am little bit off. I know that basic C datatype char is there for ASCII characters coding. But what I don´t know is, why you even need another datatype for characters. Why could not you just use 1 byte integer value to store ASCII character. If you call printf, you apecify the datatype in the call, so you could say to printf that the integer represents ASCII character. I dont know how cout resolves datatype, but I guess you could just specify it somehow. Another thing is, when you want to use Unicode, you must use datatype wchar. But, what if I would like to use some another, for example ISO, or Windows coding instead of UTF? Becouse wchar codes characters as UTF-16 or UTF-32 (I read its compiler specific). And, what if I would want to use for example some imaginary new 8 byte text coding? What datatype should I use for it? I am actually pretty confused of this, becouse I always expected that if I want to use UTF-32 instead of ASCII, I just tell compiler "get UTF-32 value of the character I typed and save it into 4 char field." I thought that text coding is to be dealt with by the end, print function for example. That I just need to specify the coding for the compiler to use, since Windows doesent use ASCII in win32 apps, I guess C compiler must convert the char I typed to ASCII from whatever the type is that windows sends to the C editor. And the last thing is, what if I want to use for example 25 Byte integer for some high math operations? C has no specify-yourself datatype. Yes, I know that this would be difficult since all the math operations would need to be changed, becouse CPU can not add 25 Bytes numbers together. But is there a way to do it? Or is there some math library for it? What if I want to compute Pi to 1000000000000000 digits? :) I know my question is pretty long, but I just wanted to explain my thoughts the best I can in English, since its not my native language it is difficult. And I believe there is simple answer to my question(s), something I missed that explains everything. I read lot about text coding, C tutorials, but nothing about his. Thank you for your time.

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• C# problem with two threads and hardware access

  - by mack369

  I'm creating an application which communicates with the device via FT2232H USB/RS232 converter. For communication I'm using FTD2XX_NET.dll library from FTDI website. I'm using two threads: first thread continuously reads data from the device the second thread is the main thread of the Windows Form Application I've got a problem when I'm trying to write any data to the device while the receiver's thread is running. The main thread simply hangs up on ftdiDevice.Write function. I tried to synchronize both threads so that only one thread can use Read/Write function at the same time, but it didn't help. Below code responsible for the communication. Note that following functions are methods of FtdiPort class. Receiver's thread private void receiverLoop() { if (this.DataReceivedHandler == null) { throw new BackendException("dataReceived delegate is not set"); } FTDI.FT_STATUS ftStatus = FTDI.FT_STATUS.FT_OK; byte[] readBytes = new byte[this.ReadBufferSize]; while (true) { lock (FtdiPort.threadLocker) { UInt32 numBytesRead = 0; ftStatus = ftdiDevice.Read(readBytes, this.ReadBufferSize, ref numBytesRead); if (ftStatus == FTDI.FT_STATUS.FT_OK) { this.DataReceivedHandler(readBytes, numBytesRead); } else { Trace.WriteLine(String.Format("Couldn't read data from ftdi: status {0}", ftStatus)); Thread.Sleep(10); } } Thread.Sleep(this.RXThreadDelay); } } Write function called from main thread public void Write(byte[] data, int length) { if (this.IsOpened) { uint i = 0; lock (FtdiPort.threadLocker) { this.ftdiDevice.Write(data, length, ref i); } Thread.Sleep(1); if (i != (int)length) { throw new BackendException("Couldnt send all data"); } } else { throw new BackendException("Port is closed"); } } Object used to synchronize two threads static Object threadLocker = new Object(); Method that starts the receiver's thread private void startReceiver() { if (this.DataReceivedHandler == null) { return; } if (this.IsOpened == false) { throw new BackendException("Trying to start listening for raw data while disconnected"); } this.receiverThread = new Thread(this.receiverLoop); //this.receiverThread.Name = "protocolListener"; this.receiverThread.IsBackground = true; this.receiverThread.Start(); } The ftdiDevice.Write function doesn't hang up if I comment following line: ftStatus = ftdiDevice.Read(readBytes, this.ReadBufferSize, ref numBytesRead);

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• How to use Wordpress' http.php in external projects?

  - by NJTechGuy

  I am trying to parse data from a pipe-delimited text file hosted on another server which in turn will be inserted in a database. My host (1and1) disabled allow_url_fopen in php.ini I guess. Error message : Warning: fopen() [function.fopen]: URL file-access is disabled in the server configuration in Code : <? // make sure curl is installed if (function_exists('curl_init')) { // initialize a new curl resource $ch = curl_init(); // set the url to fetch curl_setopt($ch, CURLOPT_URL, 'http://abc.com/data/output.txt'); // don't give me the headers just the content curl_setopt($ch, CURLOPT_HEADER, 0); // return the value instead of printing the response to browser curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); // use a user agent to mimic a browser curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.5) Gecko/20041107 Firefox/1.0'); $content = curl_exec($ch); // remember to always close the session and free all resources curl_close($ch); } else { // curl library is not installed so we better use something else } //$contents = fread ($fd,filesize ($filename)); //fclose ($fd); $delimiter = "|"; $splitcontents = explode($delimiter, $contents); $counter = ""; ?> <font color="blue" face="arial" size="4">Complete File Contents</font> <hr> <? echo $contents; ?> <br><br> <font color="blue" face="arial" size="4">Split File Contents</font> <hr> <? foreach ( $splitcontents as $color ) { $counter = $counter+1; echo "<b>Split $counter: </b> $colorn<br>"; } ?> Wordpress has this cool http.php file. Is there a better way of doing it? If not, how do I use http.php for this task? Thank you guys..

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• PHP Mcrypt - Encrypting / Decrypting file

  - by whitman6732

  Trying to write a couple of functions that will encrypt or decrypt a file and am using the class found here to try and accomplish this: http://www.itnewb.com/v/PHP-Encryption-Decryption-Using-the-MCrypt-Library-libmcrypt The encryption function below seems to work, in that it appears to encrypt the file and place it in the intended directory. I'm trying to decrypt the file now, and it just dies with the message "Failed to complete decryption" (which is coded in there...) There's nothing in the php error logs, so I'm not sure why it's failing, but as mcrypt is entirely new to me, I'm more than inclined to believe I'm doing something wrong here... Here are the functions: //ENCRYPT FILE function encryptFile() { global $cryptastic; $pass = PGPPASS; $salt = PGPSALT; $key = $cryptastic->pbkdf2($pass, $salt, 1000, 32) or die("Failed to generate secret key."); if ($handle = opendir(PATH.'/ftpd')) { while (false !== ($file = readdir($handle))) { if ($file != "." && $file != "..") { $newfile = PATH.'/encrypted/'.$file.'.txt'; $msg = file_get_contents(PATH.'/ftpd/'.$file); $encrypted = $cryptastic->encrypt($msg, $key) or die("Failed to complete encryption."); $nfile = fopen($newfile, 'w'); fwrite($nfile, $encrypted); fclose($nfile); unlink(PATH.'/ftpd/'.$file); } } closedir($handle); } //DECRYPT FILE function inFTP() { global $cryptastic; $pass = PGPPASS; $salt = PGPSALT; $key = $cryptastic->pbkdf2($pass, $salt, 1000, 32) or die("Failed to generate secret key."); if ($handle = opendir(PATH.'/encrypted')) { while (false !== ($file = readdir($handle))) { if ($file != "." && $file != "..") { $newfile = PATH.'/decrypted/'.$file; $msg = PATH.'/encrypted/'.$file; $decrypted = $cryptastic->decrypt($msg, $key) or die("Failed to complete decryption."); $nfile = fopen($newfile, 'w'); fwrite($nfile, $decrypted); fclose($nfile); //unlink(PATH.'/encrypted/'.$file); } } closedir($handle); } //$crypt->decrypt($file); }

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• Unlocking a mutex from a different thread (C++)

  - by dan

  I'm using the C++ boost::thread library, which in my case means I'm using pthreads. Officially, a mutex must be unlocked from the same thread which locks it, and I want the effect of being able to lock in one thread and then unlock in another. There are many ways to accomplish this. One possibility would be to write a new mutex class which allows this behavior. For example: class inter_thread_mutex{ bool locked; boost::mutex mx; boost::condition_variable cv; public: void lock(){ boost::unique_lock<boost::mutex> lck(mx); while(locked) cv.wait(lck); locked=true; } void unlock(){ { boost::lock_guard<boost::mutex> lck(mx); if(!locked) error(); locked=false; } cv.notify_one(); } // bool try_lock(); void error(); etc. } I should point out that the above code doesn't guarantee FIFO access, since if one thread calls lock() while another calls unlock(), this first thread may acquire the lock ahead of other threads which are waiting. (Come to think of it, the boost::thread documentation doesn't appear to make any explicit scheduling guarantees for either mutexes or condition variables). But let's just ignore that (and any other bugs) for now. My question is, if I decide to go this route, would I be able to use such a mutex as a model for the boost Lockable concept. For example, would anything go wrong if I use a boost::unique_lock< inter_thread_mutex for RAII-style access, and then pass this lock to boost::condition_variable_any.wait(), etc. On one hand I don't see why not. On the other hand, "I don't see why not" is usually a very bad way of determining whether something will work. The reason I ask is that if it turns out that I have to write wrapper classes for RAII locks and condition variables and whatever else, then I'd rather just find some other way to achieve the same effect.

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• getSymbols and using lapply, Cl, and merge to extract close prices

  - by algotr8der

  I've been messing around with this for some time. I recently started using the quantmod package to perform analytics on stock prices. I have a ticker vector that looks like the following: > tickers [1] "SPY" "DIA" "IWM" "SMH" "OIH" "XLY" "XLP" "XLE" "XLI" "XLB" "XLK" "XLU" "XLV" [14] "QQQ" > str(tickers) chr [1:14] "SPY" "DIA" "IWM" "SMH" "OIH" "XLY" "XLP" "XLE" ... I wrote a function called myX to use in a lapply call to save prices for every stock in the vector tickers. It has the following code: myX <- function(tickers, start, end) { require(quantmod) getSymbols(tickers, from=start, to=end) } I call lapply by itself library(quantmod) lapply(tickers,myX,start="2001-03-01", end="2011-03-11") > lapply(tickers,myX,start="2001-03-01", end="2011-03-11") [[1]] [1] "SPY" [[2]] [1] "DIA" [[3]] [1] "IWM" [[4]] [1] "SMH" [[5]] [1] "OIH" [[6]] [1] "XLY" [[7]] [1] "XLP" [[8]] [1] "XLE" [[9]] [1] "XLI" [[10]] [1] "XLB" [[11]] [1] "XLK" [[12]] [1] "XLU" [[13]] [1] "XLV" [[14]] [1] "QQQ" That works fine. Now I want to merge the Close prices for every stock into an object that looks like # BCSI.Close WBSN.Close NTAP.Close FFIV.Close SU.Close # 2011-01-03 30.50 20.36 57.41 134.33 38.82 # 2011-01-04 30.24 19.82 57.38 132.07 38.03 # 2011-01-05 31.36 19.90 57.87 137.29 38.40 # 2011-01-06 32.04 19.79 57.49 138.07 37.23 # 2011-01-07 31.95 19.77 57.20 138.35 37.30 # 2011-01-10 31.55 19.76 58.22 142.69 37.04 Someone recommended I try something like the following: ClosePrices <- do.call(merge, lapply(tickers, function(x) Cl(get(x)))) However I tried various combinations of this without any success. First I tried just calling lapply with Cl(x) >lapply(tickers,myX,start="2001-03-01", end="2011-03-11") Cl(myX))) > lapply(tickers,myX,start="2001-03-01", end="2011-03-11") Cl(x))) Error: unexpected symbol in "lapply(tickers,myX,start="2001-03-01", end="2011-03-11") Cl" > > lapply(tickers,myX(x),start="2001-03-01", end="2011-03-11") Cl(x))) Error: unexpected symbol in "lapply(tickers,myX(x),start="2001-03-01", end="2011-03-11") Cl" > > lapply(tickers,myX(start="2001-03-01", end="2011-03-11") Cl(x) Error: unexpected symbol in "lapply(tickers,myX(start="2001-03-01", end="2011-03-11") Cl" > lapply(tickers,myX(start="2001-03-01", end="2011-03-11") Cl(x)) Error: unexpected symbol in "lapply(tickers,myX(start="2001-03-01", end="2011-03-11") Cl" > Any guidance would be kindly appreciated.

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• Issues loading Jquery (Galleria) script from inside an i-frame (beginner javascript?)

  - by 103188530284789248582

  Hello, first of all - I'm not entirely new to javascript, but am not fluent in it as I am with html and css, and am especially new to jQuery... so please excuse me if this questions seems easy or obvious, but after days of google I still have no solution to the problem... using jQuery 1.4.2.min, jQuery-ui-1.8.1 .... the site in question: http://homecapture.ca/sets/project_index.html The scenario: I have a tabbed menu generated from an unordered list, when a menu item is clicked it reveals an iframe which links to the page containing an image gallery. I am using jQuery UI tabs for the tabbed menu, and the galleries to which I'm linking are jQuery Galleria pages, automatically generated with Jalbum. The problem: The galleria plug-in only works normally from inside of the containing iframe in Chrome, has inconsistent behaviour in IE8 (seems to work in my local copy, but won't load properly online), and is not loaded properly in Firefox. Instead of displaying a thumbnail area and the first large image, the Galleria page shows the first thumbnail only, then when it is clicked the image it links to, but if you right-click and go Back, the iframe content shows up as a properly rendered Galleria page. Jalbum generates more script in the < head of the page in addition to linking to jquery and the galleria plug-in. All of it seems to be in charge of the gallery navigation , and I have relocated it to the < body of the page, in an effort to make it load after the parent page scripts, and together with the gallery content. At this point I am not sure what else I could do to solve the problem, without digging around in all or some of the library and pluging .js files (which I am not knowledgeable enough to do without some pointers). Has anyone dealt with a similar issue? I'm seeing some solutions for manipulating iframe content from a parent page with jQuery on here, is that what I should be researching instead? Thanks in advance for all the help! ps. I tried posting some code, but it seems I do not have enough 'reputation' for things to work right on here either :)

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• Resize an array of images with OpenCV

  - by amr

  I'm passing an array of images (IplImage**) to an object in C++ using OpenCV. I'm then trying to iterate over that array and resize them all to a fixed size (150x150) I'm doing it this way: for(int i = 0; i< this->numTrainingFaces; i++) { IplImage* frame_copy = cvCreateImage( cvSize(150,150), this->faceImageArray[0]->depth, this->faceImageArray[0]->nChannels ); cout << "Created image" << endl; cvResize(this->faceImageArray[i], frame_copy); cout << "Resized image" << endl; IplImage* grey_image = cvCreateImage( cvSize( frame_copy->width, frame_copy->height ), IPL_DEPTH_8U, 1 ); cout << "Created grey image" << endl; cvCvtColor( frame_copy, grey_image, CV_RGB2GRAY ); cout << "Converted image" << endl; this->faceImageArray[i] = grey_image; cvReleaseImage(&frame_copy); cvReleaseImage(&grey_image); } But I'm getting this output, and I'm not sure why: Created image Resized image Created grey image Converted image Created image OpenCV Error: Assertion failed (src.type() == dst.type()) in cvResize, file /build/buildd/opencv-2.1.0/src/cv/cvimgwarp.cpp, line 3102 terminate called after throwing an instance of 'cv::Exception' what(): /build/buildd/opencv-2.1.0/src/cv/cvimgwarp.cpp:3102: error: (-215) src.type() == dst.type() in function cvResize Aborted I'm basically just trying to replace the image in the array with the resized one in as few steps as possible. Edit: Revised my code as follows: for(int i = 0; i< this->numTrainingFaces; i++) { IplImage* frame_copy = cvCreateImage( cvSize(150,150), this->faceImageArray[i]->depth, this->faceImageArray[i]->nChannels ); cvResize(this->faceImageArray[i], frame_copy); IplImage* grey_image = cvCreateImage( cvSize( frame_copy->width, frame_copy->height ), IPL_DEPTH_8U, 1 ); cvCvtColor( frame_copy, grey_image, CV_RGB2GRAY ); faceImageArray[i] = cvCreateImage( cvSize(grey_image->width, grey_image->height), grey_image->depth, grey_image->nChannels); cvCopy(grey_image,faceImageArray[i]); cvReleaseImage(&frame_copy); cvReleaseImage(&grey_image); } Then later on I'm performing some PCA, and get this output: OpenCV Error: Null pointer (Null pointer to the written object) in cvWrite, file /build/buildd/opencv-2.1.0/src/cxcore/cxpersistence.cpp, line 4740 But I don't think my code has got to the point where I'm explicitly calling cvWrite, so it must be part of the library. I can give a full implementation if necessary - is there anything in my code that's going to create a null pointer?

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• Please help with iPhone Memory & Images, memory usage crashing app

  - by Andrew Gray

  I have an issue with memory usage relating to images and I've searched the docs and watched the videos from cs193p and the iphone dev site on memory mgmt and performance. I've searched online and posted on forums, but I still can't figure it out. The app uses core data and simply lets the user associate text with a picture and stores the list of items in a table view that lets you add and delete items. Clicking on a row shows the image and related text. that's it. Everything runs fine on the simulator and on the device as well. I ran the analyzer and it looked good, so i then starting looking at performance. I ran leaks and everything looked good. My issue is when running Object Allocations as every time i select a row and the view with the image is shown, the live bytes jumps up a few MB and never goes down and my app eventually crashes due to memory usage. Sorting the live bytes column, i see 2 2.72MB mallocs (5.45Mb total), 14 CFDatas (3.58MB total), 1 2.74MB malloc and everything else is real small. the problem is all the related info in instruments is really technical and all the problem solving examples i've seen are just missing a release and nothing complicated. Instruments shows Core Data as the responsible library for all but one (libsqlite3.dylib the other) with [NSSQLCore _prepareResultsFromResultSet:usingFetchPlan:withMatchingRows:] as the caller for all but one (fetchResultSetReallocCurrentRow the other) and im just not sure how to track down what the problem is. i've looked at the stack traces and opened the last instance of my code and found 2 culprits (below). I havent been able to get any responses at all on this, so if anyone has any tips or pointers, I'd really appreciate it!!!! //this is from view controller that shows the title and image - (void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; self.title = item.title; self.itemTitleTextField.text = item.title; if ([item.notes length] == 0) { self.itemNotesTextView.hidden = YES; } else { self.itemNotesTextView.text = item.notes; } //this is the line instruments points to UIImage *image = item.photo.image; itemPhoto.image = image; } - (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath { if (editingStyle == UITableViewCellEditingStyleDelete) { // Delete the managed object for the given index path NSManagedObjectContext *context = [fetchedResultsController managedObjectContext]; [context deleteObject:[fetchedResultsController objectAtIndexPath:indexPath]]; // Save the context. NSError *error = nil; if (![context save:&error]) //this is the line instruments points to { NSLog(@"Unresolved error %@, %@", error, [error userInfo]); exit(-1); } } }

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• Executing a .NET Managed Assembly from SQL Server 2008 - Pro's, Con's & Recommendations

  - by RPM1984

  Hi guys, looking for opinions/recommendations/links for the following scenario im currently facing. The Platform: .NET 4.0 Web Application SQL Server 2008 The Task: Overhaul a component of the system that performs (fairly) complex mathematical operations based on a specific user activity, and updates numerous tables in the database. A common user activity might be "Bob" decides to post a forum topic. This results in (the end-solution) needing to look at various factors (about the post he did), then after doing some math based on lookup values/ratios as well as other data in the database, inserting some other data as a result of these operations. The Options: Ok - so here's what im thinking. Although it would be much easier to do this in C# (LINQ-SQL) it doesnt make much sense as the majority of the computations are based on values in the db, and it will get difficult to control/optimize/debug the LINQ over time. Hence, im leaning towards created a managed assembly (C# Class Library) that contains the lookup values (constants) as well as leveraging the math classes in the existing .NET BCL. Basically i'd expose a few methods that can be called by the T-SQL Stored Procedures. This to me has the following advantages: Simplicity of math. Do complex math in .NET vs complex math in T-SQL. No brainer. =) Abstraction of computatations, configurable "lookup" values and business logic from raw T-SQL. T-SQL only needs to care about the data, simplifying the stored procedures and making it easier to maintain. When it needs to do math it delegates off to the managed assembly. So, having said that - ive never done this before (call .NET assmembly from T-SQL), and after some googling the best site i could come up with is here, which is useful but outdated. So - what am i asking? Well, firstly - i need some better references on how to actually do this. "This" being how to call a C# .NET 4 Assembly from within T-SQL Stored Procedures in SQL Server 2008. Secondly, who out there has done this, what problems (if any) did you face? Realize this may be difficult to provide a "correct answer", so ill try to give it to whoever gives me the answer with a combination of good links and a list of pro's/con's/problems with this implementation. Cheers!

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• UITableViewCell outlets not set during bundle load (possibly very elementary question)

  - by Jan Zich

  What are the most common reasons for an outlet (a class property) not being set during a bundle load? I'm sorry; most likely I'm not using the correct terms. It's my first steps with iPhone OS development and Objective-C, so please bear with me. Here is more details. Basically, I'm trying to create a table view based form with a fixed number of static rows. I followed this example: http://developer.apple.com/iphone/library/documentation/userexperience/conceptual/TableView_iPhone/TableViewCells/TableViewCells.html Scroll down to The Technique for Static Row Content please. I have one nib file with one table view, three table cells and all connections set as in the example. The problem is that the corresponding cell properties in my controller are never initialised. I get an exception in cellForRowAtIndexPath complaining that the returned cell is nil: UITableView dataSource must return a cell from tableView:cellForRowAtIndexPath. Here are the relevant parts from the implementation of the controller: @synthesize cellA; @synthesize cellB; @synthesize cellC; - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { return 1; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return 3; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { switch (indexPath.row) { case 0: return cellA; break; case 1: return cellB; break; case 2: return cellC; break; default: return nil; } } And here is the interface part: @interface AssociatePhoneViewController : UITableViewController { UITableViewCell *cellA; UITableViewCell *cellB; UITableViewCell *cellB; } @property (nonatomic, retain) IBOutlet UITableViewCell *cellA; @property (nonatomic, retain) IBOutlet UITableViewCell *cellB; @property (nonatomic, retain) IBOutlet UITableViewCell *cellC; @end This must be possibly one of the the most embarrassing questions on StackOverflow. It looks like the most basic example code. Is is possible that the cells are not instantiated with the nib file? I have them on the same level before the tabula view in the nib file. I tried to move them after the table view, but it did not make any difference. Are table cells in some way special? Do I need to set some flag or some property on them in the nib file? I was under the impression that all classes (views, windows, controllers …) listed in a nib file are simply instantiated (and linked using the provided connections). Could it possibly be some memory issue? The cell properties in my controller are not defined in any special way.

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• Overloading framework methods in objective-c, or retaining local changes with framework updates.

  - by Jeff B

  I am using cocos2d to build an iPhone game. It's mostly done, but along the way I came across some things that I would like to handle better. I am fairly new to Objective C, and honestly I do more Perl scripting in my day-to-day job than anything, so my C skills are a little rusty. One of them is the fact that I have modified cocos2d files for some specific cases in my game. However, when I update to a new version, I have to manually pull my changes forward. So, the question is, what is the best way to deal with this? Some options I have thought of: Overload/redefine the cocos2d classes. I was under the impression that I cannot overload existing class functions, so I don't think this will work. Create patches that I re-apply after library updates. I don't think this will work as the new files won't necessarily be the same as the old ones, and if they were, I could just copy the whole file forward. Turn in my changes to Cocos2d. Not an option as my changes are very specific to my application. Am I missing something obvious? UPDATE: I will explain what I am doing to be more clear. Cocos2d has a CCNode object, which can contain children, etc. I added a shadow, which is very similar to a child, but handled a little differently. The shadow has an offset from the parent, and translates with it's parent, rotates around it's own center when the parent rotates, etc. The shadow is not included as a true child, however, so given the correct z-index, the shadows can render under ALL other objects, but still move with the parent. To do this I added addShadow functions to CCNode, and modified the setPosition and setRotate functions to move the shadowSprite: CCNode.m: -(id) init { if ((self=[super init]) ) { ... shadowSprite_ = nil; ... } } ... -(BOOL) addShadow: (CCNode*) child offset: (CGPoint) offset { shadowSprite_ = child; shadowSprite_.position = CGPointMake(position_.x+offset.x, position_.y+offset.y); return YES; } ... -(void) setRotation: (float)newRotation { rotation_ = newRotation; isTransformDirty_ = isInverseDirty_ = YES; if(shadowSprite_) { [shadowSprite_ setRotation: newRotation]; } } There is more, of course, including the prototypes in the .h file, but that is the basics. I don't think I need shadowSprite to be a property, because I don't need to access it after it has been added.

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• What's the best way to return stuff from a PHP function, and simultaneously trigger a jQuery action?

  - by Jack Webb-Heller

  So the title is a tad ambiguous, but I'll try and give an example. Basically, I have an 'awards' system (similar to that of StackOverflow's badges) in my PHP/CodeIgniter site, and I want, as soon as an award is earned, a notification to appear to the user. Now I'm happy to have this appear on the next page load, but, ideally I'd like it to appear as soon as the award is transactioned since my site is mostly Ajax-powered and there may not be page reloads very often. The way the system works currently, is: 1) If the user does something to trigger the earning of an award, CodeIgniter does this: $params['user_id'] = $this->tank_auth->get_user_id(); $params['award_id'] = 1; // (I have a database table with different awards in) $this->awards->award($params); 2) My custom library, $this->awards, runs the award function: function award($params) { $sql = $this->ci->db->query("INSERT INTO users_awards (user_id, award_id) VALUES ('".$params['user_id']."','".$params['award_id']."') ON DUPLICATE KEY UPDATE duplicate=duplicate+1"); $awardinfo = $this->ci->db->query("SELECT * FROM awards WHERE id = ".$params['award_id']); // If it's the 'first time' the user has gotten the award (e.g. they've earnt it) if ($awardinfo->row('duplicate') == 0) { $params['title'] = $awardinfo->row('title'); $params['description'] = $awardinfo->row('description'); $params['iconpath'] = $awardinfo->row('iconpath'); $params['percentage'] = $awardinfo->row('percentage'); return $params; } } So, it awards the user (and if they've earnt it twice, updates a useless duplicate field by one), then checks if it's the first time they've earnt it (so it can alert them of the award). If so, it gets the variables (title of the award, the award description, the path to an icon to display for the award, and finally the percentage of users who have also got this award) and returns them as an array. So... that's that. Now I'd like to know, what's the best way to do this? Currently my Award-giving bit is called from a controller, but I guess if I want this to trigger via Ajax, then the code should be placed in a View file...? To sum it up: I need the returned award data to appear without a page refresh. What's the best way of doing this? (I'm already using jQuery on my page). Thanks very much everybody! Jack

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• how to: handle exceptions, best practices

  - by b0x0rz

  need to implement a global error handling, so maybe you can help out with the following example... i have this code: public bool IsUserAuthorizedToSignIn(string userEMailAddress, string userPassword) { // get MD5 hash for use in the LINQ query string passwordSaltedHash = this.PasswordSaltedHash(userEMailAddress, userPassword); // check for email / password / validity using (UserManagementDataContext context = new UserManagementDataContext()) { var users = from u in context.Users where u.UserEMailAdresses.Any(e => e.EMailAddress == userEMailAddress) && u.UserPasswords.Any(p => p.PasswordSaltedHash == passwordSaltedHash) && u.IsActive == true select u; // true if user found return (users.Count() == 1) ? true : false; } } and the md5 as well: private string PasswordSaltedHash(string userEMailAddress, string userPassword) { MD5 hasher = MD5.Create(); byte[] data = hasher.ComputeHash(Encoding.Default.GetBytes(userPassword + userEMailAddress)); StringBuilder stringBuilder = new StringBuilder(); for (int i = 0; i < data.Length; i++) { stringBuilder.Append(data[i].ToString("x2")); } Trace.WriteLine(String.Empty); Trace.WriteLine("hash: " + stringBuilder.ToString()); return stringBuilder.ToString(); } so, how would i go about handling exceptions from these functions? they first one is called from the Default.aspx page. the second one is only called from other functions from the class library. what is the best practice? surround code INSIDE each function with try-catch surround the FUNCTION CALL with try-catch something else?? what to do if exceptions happen? in this example: this is a user sign in, so somehow even if everything fails, the user should get some meaningful info - along the lines: sign in ok (just redirect), sign in not ok (wrong user name / password), sign in not possible due to internal problems, sorry (exception happened). for the first function i am worried if there is a problem with database access. not sure if there is anything that needs to be handled in the second one. thnx for the info. how would you do it? need specific info on this (easier for me to understand), but also general info on how to handle other tasks/functions. i looked around the internet but everyone has different things to say, so unsure what to do... will go with either most votes here, or most logicaly explained answer :) thank you.

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• java.util.zip - ZipInputStream v.s. ZipFile

  - by lucho

  Hello, community! I have some general questions regarding the java.util.zip library. What we basically do is an import and an export of many small components. Previously these components were imported and exported using a single big file, e.g.: <component-type-a id="1"/> <component-type-a id="2"/> <component-type-a id="N"/> <component-type-b id="1"/> <component-type-b id="2"/> <component-type-b id="N"/> Please note that the order of the components during import is relevant. Now every component should occupy its own file which should be externally versioned, QA-ed, bla, bla. We decided that the output of our export should be a zip file (with all these files in) and the input of our import should be a similar zip file. We do not want to explode the zip in our system. We do not want opening separate streams for each of the small files. My current questions: Q1. May the ZipInputStream guarantee that the zip entries (the little files) will be read in the same order in which they were inserted by our export that uses ZipOutputStream? I assume reading is something like: ZipInputStream zis = new ZipInputStream(new BufferedInputStream(fis)); ZipEntry entry; while((entry = zis.getNextEntry()) != null) { //read from zis until available } I know that the central zip directory is put at the end of the zip file but nevertheless the file entries inside have sequential order. I also know that relying on the order is an ugly idea but I just want to have all the facts in mind. Q2. If I use ZipFile (which I prefer) what is the performance impact of calling getInputStream() hundreds of times? Will it be much slower than the ZipInputStream solution? The zip is opened only once and ZipFile is backed by RandomAccessFile - is this correct? I assume reading is something like: ZipFile zipfile = new ZipFile(argv[0]); Enumeration e = zipfile.entries();//TODO: assure the order of the entries while(e.hasMoreElements()) { entry = (ZipEntry) e.nextElement(); is = zipfile.getInputStream(entry)); } Q3. Are the input streams retrieved from the same ZipFile thread safe (e.g. may I read different entries in different threads simultaneously)? Any performance penalties? Thanks for your answers!

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• Netsuite - how to specify record_type for getall request

  - by Dvporg

  I want to get a list of all InventoryItems According to this document: https://system.netsuite.com/help/helpcenter/en_US/Output/Help/SuiteCloudCustomizationScriptingWebServices/SuiteTalkWebServices/getAll.html I'm forming the following request: <env:Envelope xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:platformMsgs="urn:platform_2013_1.webservices.netsuite.com" xmlns:env="http://schemas.xmlsoap.org/soap/envelope/"> <env:Header> <passport> <email>******</email> <password>******</password> <account>******</account> </passport> </env:Header> <env:Body> <platformMsgs:getAll> <recordType>InventoryItem</recordType> </platformMsgs:getAll> </env:Body> </env:Envelope> But receiving response with the error: <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <soapenv:Header> <platformMsgs:documentInfo xmlns:platformMsgs="urn:messages_2013_1.platform.webservices.netsuite.com"> <platformMsgs:nsId>WEBSERVICES_969904_100920131651936419141601801_cbf1690968b43</platformMsgs:nsId> </platformMsgs:documentInfo> </soapenv:Header> <soapenv:Body> <getAllResponse xmlns="urn:platform_2013_1.webservices.netsuite.com"> <platformCore:getAllResult xmlns:platformCore="urn:core_2013_1.platform.webservices.netsuite.com"> <platformCore:status isSuccess="false"> <platformCore:statusDetail type="ERROR"> <platformCore:code>GETALL_RCRD_TYPE_REQD</platformCore:code> <platformCore:message>The getAll record type is required.</platformCore:message> </platformCore:statusDetail> </platformCore:status> </platformCore:getAllResult> </getAllResponse> </soapenv:Body> </soapenv:Envelope> I've tried to request currencies, states - the response always the same I've tried following variants: <GetAllRecordType>inventoryItem</GetAllRecordType> and <recordType>inventoryItem</recordType> and <GetAllRecordType>currency</GetAllRecordType> and <recordType>currency</recordType> with the same response: <platformCore:message>The getAll record type is required.</platformCore:message> According to https://webservices.netsuite.com/xsd/platform/v2013_2_0/coreTypes.xsd - I've specified correctly recordType (btw I've also tried without any success) I'm using ruby and there is no complete library for ruby. The one that is exists doesn't contain almost all things I'm going to use. Can someone help me what I'm doing wrong or may be someone have working example

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• send sms in asp.net by gsm modem

  - by danar jabbar

  I devloped an asp.net application to send sms from gsm modem to destination base on URL from the browser I used a library that developed by codeproject http://www.codeproject.com/articles/20420/how-to-send-and-receive-sms-using-gsm-modem but I get problem when I request form two browsers at same time and I want to make the my code detect that the modem is use by another process at the time here is my code: DeviceConnection deviceConnection = new DeviceConnection(); protected void Page_Load(object sender, EventArgs e) { try { if (Request.QueryString["destination"] != null && Request.QueryString["text"] != null) { deviceConnection.setBaudRate(9600); deviceConnection.setPort(12); deviceConnection.setTimeout(200); SendSms sendSms = new SendSms(deviceConnection); if (deviceConnection.getConnectionStatus()) { sendSms.strReciverNo = Request.QueryString["destination"]; sendSms.strTextMessage = Request.QueryString["text"]; if (sendSms.sendSms()) { Response.Write("Mesage successfuly sent to " + Request.QueryString["destination"]); } else { Response.Write("Message was not sent"); } } } } catch (Exception ex) { Console.WriteLine("Index "+ex.StackTrace); } } This is SendSms class: class SendSms { DeviceConnection deviceConnection; public SendSms(DeviceConnection deviceConnection) { this.deviceConnection = deviceConnection; } private string reciverNo; private string textMessage; private delegate void SetTextCallback(string text); public string strReciverNo { set { this.reciverNo = value; } get { return this.reciverNo; } } public string strTextMessage { set { this.textMessage = value; } get { return this.textMessage; } } public bool sendSms() { try { CommSetting.Comm_Port = deviceConnection.getPort();//GsmCommMain.DefaultPortNumber; CommSetting.Comm_BaudRate = deviceConnection.getBaudRate(); CommSetting.Comm_TimeOut = deviceConnection.getTimeout();//GsmCommMain.DefaultTimeout; CommSetting.comm = new GsmCommMain(deviceConnection.getPort() , deviceConnection.getBaudRate(), deviceConnection.getTimeout()); // CommSetting.comm.PhoneConnected += new EventHandler(comm_PhoneConnected); if (!CommSetting.comm.IsOpen()) { CommSetting.comm.Open(); } SmsSubmitPdu smsSubmitPdu = new SmsSubmitPdu(strTextMessage, strReciverNo, ""); smsSubmitPdu.RequestStatusReport = true; CommSetting.comm.SendMessage(smsSubmitPdu); CommSetting.comm.Close(); return true; } catch (Exception exception) { Console.WriteLine("sendSms " + exception.StackTrace); CommSetting.comm.Close(); return false; } } public void recive(object sender, EventArgs e) { Console.WriteLine("Message received successfuly"); } } }

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• E4X in ActionScript help needed

  - by voipsecuritydigest.com

  Here is the XML How using E4X read values of nodes <status>??</status> and of node <invisible value="false"/> ? <?xml version="1.0" encoding="utf-8"?> <s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark" creationComplete="init()"> <fx:Declarations> <!-- Place non-visual elements (e.g., services, value objects) here --> </fx:Declarations> <fx:Script> <![CDATA[ var xml:XML = <iq type="result" id="ss-1"> <query status-min-ver="1" status-max="512" status-list-contents-max="5" status-list-max="3" xmlns="google:shared-status"> <status> ?? </status> <show> default </show> <status-list show="default"> <status> ?? </status> <status> ? </status> <status> ?? </status> </status-list> <status-list show="dnd"> <status> ?? </status> <status> dnd, i have bad mood </status> <status> showering </status> <status> ??_???¦ </status> <status> ? </status> </status-list> <invisible value="false"/> </query> </iq> public function init() { trace(xml.query.invisible.@value); } ]]> </fx:Script> </s:Application>

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• CI pagination, POST problem

  - by Gwood

  Okay, I am pretty new in CI and I am stuck on pagination. I am performing this pagination on a record set that is result of a query. Now everything seems to be working fine. But there’s some problem probably with the link. I am displaying 10 results per page. Now if the results are less than 10 then it’s fine. Or If I pull up the entire records in the table it works fine. But in case the result is more than 10 rows, then the first 10 is perfectly displayed, and when I click on the pagination link to get to the next page the next page displays the rest of the results from the query as well as, other records in the table. ??? I am confused.. Any help?? Here’s the model code I am using .... function getTeesLike($field,$param) { $this-db-like($field,$param); $this-db-limit(10, $this-uri-segment(3)); $query=$this-db-get(‘shirt’); if($query-num_rows()0){ return $query-result_array(); } } function getNumTeesfromQ($field,$param) { $this-db-like($field,$param); $query=$this-db-get(‘shirt’); return $query-num_rows(); } And here’s the controller code .... $KW=$this-input-post(‘searchstr’); $this-load-library(‘pagination’); $config[‘base_url’]=‘http://localhost/cit/index.php/tees/show/’; $config[‘total_rows’]=$this-T-getNumTeesfromQ(‘Title’,$KW); $config[‘per_page’]=‘10’; $this-pagination-initialize($config); $data[‘tees’]=$this-T-getTeesLike(‘Title’,$KW); $data[‘title’]=‘Displaying Tees data’; $data[‘header’]=‘Tees List’; $data[‘links’]=$this-pagination-create_links(); $this-load-view(‘tee_res’, $data); //What am I doing wrong here ???? Pls help ... I guess the problem is with the $KW=$this-input-post(‘searchstr’); .. Because if I hard code a value for $KW it works fine. May be I should use POST differently ..but how do I pass the value from the form without POSTING it , its CI so not GET ... ??????

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• How to use constraint programming for optimizing shopping baskets?

  - by tangens

  I have a list of items I want to buy. The items are offered by different shops and different prices. The shops have individual delivery costs. I'm looking for an optimal shopping strategy (and a java library supporting it) to purchase all of the items with a minimal total price. Example: Item1 is offered at Shop1 for $100, at Shop2 for $111. Item2 is offered at Shop1 for $90, at Shop2 for $85. Delivery cost of Shop1: $10 if total order < $150; $0 otherwise Delivery cost of Shop2: $5 if total order < $50; $0 otherwise If I buy Item1 and Item2 at Shop1 the total cost is $100 + $90 +$0 = $190. If I buy Item1 and Item2 at Shop2 the total cost is $111 + $85 +$0 = $196. If I buy Item1 at Shop1 and Item2 at Shop2 the total cost is $100 + $10 + $85 + $0 = 195. I get the minimal price if I order Item1 and Item2 at Shop1: $190 What I tried so far I asked another question before that led me to the field of constraint programming. I had a look at cream and choco, but I did not figure out how to create a model to solve my problem. | shop1 | shop2 | shop3 | ... ----------------------------------------- item1 | p11 | p12 | p13 | item2 | p21 | p22 | p23 | . | | | | . | | | | ----------------------------------------- shipping | s1 | s2 | s3 | limit | l1 | l2 | l3 | ----------------------------------------- total | t1 | t2 | t3 | ----------------------------------------- My idea was to define these constraints: each price "p xy" is defined in the domain (0, c) where c is the price of the item in this shop only one price in a line should be non zero if one or more items are bought from one shop and the sum of the prices is lower than limit, then add shipping cost to the total cost shop total cost is the sum of the prices of all items in a shop total cost is the sum of all shop totals The objective is "total cost". I want to minimize this. In cream I wasn't able to express the "if then" constraint for conditional shipping costs. In choco these constraints exist, but even for 5 items and 10 shops the program was running for 10 minutes without finding a solution. Question How should I express my constraints to make this problem solvable for a constraint programming solver?

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• SQLite bulk insert on iPhone not working

  - by App_beginner

  Hi. I have been struggling with this seeminly easy problem for 48 hours, and I am no closer to a solution. So I was hoping that someone might be able to help me. I am building a app, that use a combination of a local (SQLite) database and an online database (PHP/MYSQL). The app is nearly finished. Checked for leaks and work like a charm. However the very last part is the part I have struggled with. On launch, I want the app to check for changes to the online databse, and if there is. I want it to download and parse a xml file containing the changes. Everything is working fine this far. But when I try to bulk insert my parsed data to my database, the app crashes, giving a NSInternalInconsistency error. Due to the database returning SQLITE_MISUSE. I have done a lot of googling, but am still unable to solve my problem. So I am putting the code here, hoping that someone can help me fix this. And I know that I should have used core data for this. But this is the very last part I am struggling with, and I am very reluctant to changing my entire code now. Core data will have to come in the update. Here is the error I recieve: Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Error while inserting data. 'library routine called out of sequence'' Here is my code: -(void)UpdateDatabase:(const char *)_query NewValues:(NSMutableArray *)_odb dbn:(NSString *)_dbn dbp:(NSString *)_dbp { sqlite3 *database; NSMutableArray *NewValues = _odb; int i; const char *query = _query; sqlite3_stmt *addStmt; for (i = 1; i < [NewValues count]; i++) { if(sqlite3_prepare_v2(database, query, -1, &addStmt, NULL) == SQLITE_OK) { sqlite3_bind_text(addStmt, 1, [[[NewValues objectAtIndex:i] name] UTF8String], -1, SQLITE_TRANSIENT); sqlite3_bind_text(addStmt, 2, [[[NewValues objectAtIndex:i] city]UTF8String], -1, SQLITE_TRANSIENT); sqlite3_bind_double(addStmt, 3, [[[NewValues objectAtIndex:i] lat] doubleValue]); sqlite3_bind_int(addStmt, 4, [[[NewValues objectAtIndex:i] long] doubleValue]); sqlite3_bind_int(addStmt, 5, [[[NewValues objectAtIndex:i] code] intValue]); } if(SQLITE_DONE != sqlite3_step(addStmt)) { NSAssert1(0, @"Error while inserting data. '%s'", sqlite3_errmsg(database)); } //Reset the add statement. sqlite3_reset(addStmt); } }

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• The best way to separate admin functionality from a public site?

  - by AndrewO

  I'm working on a site that's grown both in terms of user-base and functionality to the point where it's becoming evident that some of the admin tasks should be separate from the public website. I was wondering what the best way to do this would be. For example, the site has a large social component to it, and a public sales interface. But at the same time, there's back office tasks, bulk upload processing, dashboards (with long running queries), and customer relations tools in the admin section that I would like to not be effected by spikes in public traffic (or effect the public-facing response time). The site is running on a fairly standard Rails/MySQL/Linux stack, but I think this is more of an architecture problem than an implementation one: mainly, how does one keep the data and business logic in sync between these different applications? Some strategies that I'm evaluating: 1) Create a slave database of the public facing database on another machine. Extract out all of the model and library code so that it can be shared between the applications. Create new controllers and views for the admin interfaces. I have limited experience with replication and am not even sure that it's supposed to be used this way (most of the time I've seen it, it's been for scaling out the read capabilities of the same application, rather than having multiple different ones). I'm also worried about the potential for latency issues if the slave is not on the same network. 2) Create new more task/department-specific applications and use a message oriented middleware to integrate them. I read Enterprise Integration Patterns awhile back and they seemed to advocate this for distributed systems. (Alternatively, in some cases the basic Rails-style RESTful API functionality might suffice.) But, I have nightmares about data synchronization issues and the massive re-architecting that this would entail. 3) Some mixture of the two. For example, the only public information necessary for some of the back office tasks is a read-only completion time or status. Would it make sense to have that on a completely separate system and send the data to public? Meanwhile, the user/group admin functionality would be run on a separate system sharing the database? The downside is, this seems to keep many of the concerns I have with the first two, especially the re-architecting. I'm sure the answers are going to be highly dependent on a site's specific needs, but I'd love to hear success (or failure) stories.

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• What am I missing in this ASP.NET XSS Security Helper class?

  - by smartcaveman

  I need a generic method for preventing XSS attacks in ASP.NET. The approach I came up with is a ValidateRequest method that evaluates the HttpRequest for any potential issues, and if issues are found, redirect the user to the same page, but in a away that is not threatening to the application. (Source code below) While I know this method will prevent most XSS attacks, I am not certain that I am adequately preventing all possible attacks while also minimizing false positives. So, what is the most effective way to adequately prevent all possible attacks, while minimizing false positives? Are there changes I should make to the helper class below, or is there an alternative approach or third party library that offers something more convincing? public static class XssSecurity { public const string PotentialXssAttackExpression = "(http(s)*(%3a|:))|(ftp(s)*(%3a|:))|(javascript)|(alert)|(((\\%3C) <)[^\n]+((\\%3E) >))"; private static readonly Regex PotentialXssAttackRegex = new Regex(PotentialXssAttackExpression, RegexOptions.IgnoreCase); public static bool IsPotentialXssAttack(this HttpRequest request) { if(request != null) { string query = request.QueryString.ToString(); if(!string.IsNullOrEmpty(query) && PotentialXssAttackRegex.IsMatch(query)) return true; if(request.HttpMethod.Equals("post", StringComparison.InvariantCultureIgnoreCase)) { string form = request.Form.ToString(); if (!string.IsNullOrEmpty(form) && PotentialXssAttackRegex.IsMatch(form)) return true; } if(request.Cookies.Count > 0) { foreach(HttpCookie cookie in request.Cookies) { if(PotentialXssAttackRegex.IsMatch(cookie.Value)) { return true; } } } } return false; } public static void ValidateRequest(this HttpContext context, string redirectToPath = null) { if(context == null || !context.Request.IsPotentialXssAttack()) return; // expire all cookies foreach(HttpCookie cookie in context.Request.Cookies) { cookie.Expires = DateTime.Now.Subtract(TimeSpan.FromDays(1)); context.Response.Cookies.Set(cookie); } // redirect to safe path bool redirected = false; if(redirectToPath != null) { try { context.Response.Redirect(redirectToPath,true); redirected = true; } catch { redirected = false; } } if (redirected) return; string safeUrl = context.Request.Url.AbsolutePath.Replace(context.Request.Url.Query, string.Empty); context.Response.Redirect(safeUrl,true); } }

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