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• ORGetValue from Offline Registry - ERROR_MORE_DATA

  - by user314749

  I am trying to create an offline registry in memory using the offreg.dll provided in the windows ddk 7 package. You can find out more information on the offreg.dll here: MSDN Currently, while attempting to read a value from an open registry hive / key I receive the following error: 234 or ERROR_MORE_DATA Here is the .h code that contains ORGetValue: DWORD ORAPI ORGetValue ( __in ORHKEY Handle, __in_opt PCWSTR lpSubKey, __in_opt PCWSTR lpValue, __out_opt PDWORD pdwType, __out_bcount_opt(*pcbData) PVOID pvData, __inout_opt PDWORD pcbData ); Here is the code that I am using to pull the data [DllImport("offreg.dll", CharSet = CharSet.Auto, EntryPoint = "ORGetValue", SetLastError = true, CallingConvention = CallingConvention.StdCall)] public static extern uint ORGetValue(IntPtr Handle, string lpSubKey, string lpValue, out uint pdwType, out string pvData, out uint pcbData); IntPtr myHive; IntPtr myKey; string myValue; uint pdwtype; uint pcbdata; uint ret3 = ORGetValue(myKey, "", "DefaultUserName", out pdwtype, out myValue, out pcbdata); The goal is to be able to read myValue as a string. I am not sure if I need to use marshaling... or a second call with an adjusted buffer.. Or really how to adjust the buffer in C#. Any help or pointers would be greatly appreciated. Thank you.

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• How to make a cell in a datagrid readonly based the content on another cell in SL4?

  - by Nair

  I have two columns, the second column depends on the content on the first column. By default, the second columns is readonly. When I enter some valid value, I want the second column to become editable. To achive this, I created a cell template and cell edit template on the second column where back ground and read only bound to the first column. On load, the first column is null so my second columns comes correctly as read only. Following is Cell Template for second column, where the background color is set by based on the first column. <DataTemplate> <Grid> <Border Background="{Binding FristColumn,Converter={StaticResource ColorConverter}}"/> <TextBlock Text="{Binding SecondColumn, Converter={StaticResource NumberFormatter}}" HorizontalAlignment="Stretch" VerticalAlignment="Center" Margin="0"/> </Grid> </DataTemplate> Following is cell edit template for second column to make it editable <DataTemplate> <Grid> <TextBox Text="{Binding SecondColumn, Mode=TwoWay, Converter={StaticResource NumberFormatter}}" Margin="0" HorizontalAlignment="Right" IsReadOnly="{Binding FirstColumn, Converter={StaticResource readOnlyConverter}, ConverterParameter=FirstColumn}" Background="{Binding Depend,Converter={StaticResource ColorConverter}, ConverterParameter=FirstColumn}" /> </Grid> </DataTemplate> With these two in place, when enter the valid value in the first column, I was expecting the second column color to change but it does not. But If I double click on the cell then it behaves properly based on the first cell. Is there some thing I am missing?

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• Rot13 for numbers.

  - by dreeves

  EDIT: Now a Major Motion Blog Post at http://messymatters.com/sealedbids The idea of rot13 is to obscure text, for example to prevent spoilers. It's not meant to be cryptographically secure but to simply make sure that only people who are sure they want to read it will read it. I'd like to do something similar for numbers, for an application involving sealed bids. Roughly I want to send someone my number and trust them to pick their own number, uninfluenced by mine, but then they should be able to reveal mine (purely client-side) when they're ready. They should not require further input from me or any third party. (Added: Note the assumption that the recipient is being trusted not to cheat.) It's not as simple as rot13 because certain numbers, like 1 and 2, will recur often enough that you might remember that, say, 34.2 is really 1. Here's what I'm looking for specifically: A function seal() that maps a real number to a real number (or a string). It should not be deterministic -- seal(7) should not map to the same thing every time. But the corresponding function unseal() should be deterministic -- unseal(seal(x)) should equal x for all x. I don't want seal or unseal to call any webservices or even get the system time (because I don't want to assume synchronized clocks). (Added: It's fine to assume that all bids will be less than some maximum, known to everyone, say a million.) Sanity check: > seal(7) 482.2382 # some random-seeming number or string. > seal(7) 71.9217 # a completely different random-seeming number or string. > unseal(seal(7)) 7 # we always recover the original number by unsealing.

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• What are some programming techniques for converting SD images to HD images

  - by Dr Dork

  I'm taking programming class and instructor loves to work with images so most of our assignments involve manipulating raw RGB image data. One of our assignments is to implement a standard image converter that converts SD images to HD images and vice versa. I always take advantage of these types of assignments to go a little beyond what we were asked to do, so I added a basic anti-aliasing process that uses the average pixel color of the 3x3 surrounding pixels to improve the converted image. While it helps a bit, the resulting image still doesn't look good, which is ok because it's not expected to for the assignment. I've learned that converting an SD to HD images has shown to be much harder than down sampling to SD from HD just because SD to HD effectively involves increasing resolution when it is not there. Obviously, it is hard to create pixels from nothing, but I'd like enhance my anti-aliasing to something that provides better results when upscaling an image. Most of the techniques I find and read on the internet are far beyond my level of image processing and programming. Can anybody suggest any better methods or processes to create good HD content from SD content that may be within my programming skill level? I know that's a difficult thing to gauge since you don't know me, but perhaps knowing that I can write c++ code to read in raw RGB data and upscale/downscale it with simple average-anti-aliasing will give you an idea. Thanks in advance for all your help!

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• Java process is not terminating after starting an external process

  - by tangens

  On Windows I've started a program "async.cmd" with a ProcessBuilder like this: ProcessBuilder processBuilder = new ProcessBuilder( "async.cmd" ); processBuilder.redirectErrorStream( true ); processBuilder.start(); Then I read the output of the process in a separate thread like this: byte[] buffer = new byte[ 8192 ]; while( !interrupted() ) { int available = m_inputStream.available(); if( available == 0 ) { Thread.sleep( 100 ); continue; } int len = Math.min( buffer.length, available ); len = m_inputStream.read( buffer, 0, len ); if( len == -1 ) { throw new CX_InternalError(); } String outString = new String( buffer, 0, len ); m_output.append( outString ); } Now it happened that the content of the file "async.cmd" was this: REM start a command window start cmd /k The process that started this extenal program terminated (process.waitFor() returned the exit value). Then I sent an readerThread.interrupt() to the reader thread and the thread terminated, too. But there was still a thread running that wasn't terminating. This thread kept my java application running even if it exited its main method. With the debugger (eclipse) I wasn't able to suspend this thread. After I quit the opened command window, my java program exited, too. Question How can I quit my java program while the command window stays open?

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• Problem with python urllib

  - by mudder

  I'm getting an error when ever I try to pull down a web page with urllib.urlopen. I've disabled windows firewall and my AV so its not that. I can access the pages in my browser. I even reinstalled python to rule out it being a broken urllib. Any help would be greatly appreciated. >>> import urllib >>> h = urllib.urlopen("http://www.google.com").read() Traceback (most recent call last): File "<pyshell#1>", line 1, in <module> h = urllib.urlopen("http://www.google.com").read() File "C:\Python26\lib\urllib.py", line 86, in urlopen return opener.open(url) File "C:\Python26\lib\urllib.py", line 205, in open return getattr(self, name)(url) File "C:\Python26\lib\urllib.py", line 344, in open_http h.endheaders() File "C:\Python26\lib\httplib.py", line 904, in endheaders self._send_output() File "C:\Python26\lib\httplib.py", line 776, in _send_output self.send(msg) File "C:\Python26\lib\httplib.py", line 735, in send self.connect() File "C:\Python26\lib\httplib.py", line 716, in connect self.timeout) File "C:\Python26\lib\socket.py", line 514, in create_connection raise error, msg IOError: [Errno socket error] [Errno 10061] No connection could be made because the target machine actively refused it >>>

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• Powershell - Splitting string into seperate components

  - by TheD

  I am writing a script which will basically do the following: Read from a text file some arguements: DriveLetter ThreeLetterCode ServerName VolumeLetter Integer Eg. W MSS SERVER01 C 1 These values happen to form a folder destination W:\MSS\, and a filename which works in the following naming convention: SERVERNAME_VOLUMELETTER_VOL-b00X-iYYY.spi - Where The X is the Integer above The value Y I need to work out later, as this happens to be the value of the incremental image (backups) and I need to work out the latest incremental. So at the moment -- Count lines in file, and loop for this many lines. $lines = Get-Content -Path PostBackupCheck-Textfile.txt | Measure-Object -Line for ($i=0; $i -le $lines.Lines; $i++) Within this loop I need to do a Get-Content to read off the line I am currently looking at i.e. line 0, line 1, line 2, as there will be multiple lines in the format I wrote at the beginning and split the line into an array, whereby each part of the file, as seen above naming convention, is in a[0], a[1], a[2]. etc The reason for this is because, I need to then sort the folder that contains these, find the latest file, by date, and take the _iXXX.spi part and place this into the array value a[X] so I then have a complete filename to mount. This value will replace iYYY.spi It's a little complex because I also have to make sure when I do a Get-ChildItem with -Include before I sort it all by date, I am only including the filename that matches the arguements fed to it from the text file : So, SERVER01_C_VOL-b001-iYYY.spi and not anything else. i.e. not SERVER01_D_VOL-b001-iYYY.spi Then take the iYYY value from the sort on the Get-ChildItem -Include and place that into the appropriate array item. I've literally no idea where to start, so any ideas are appreciated! Hopefully I've explained in enough detail. I have also placed the code on Pastebin: http://pastebin.com/vtFifTW6 Thanks!

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• Android: Unable to make httprequest behind firewall

  - by Yang

  The standard getUrlContent works welll when there is no firewall. But I got exceptions when I try to do it behind a firewall. I've tried to set "http proxy server" in AVD manager, but it didn't work. Any idea how to correctly set it up? protected static synchronized String getUrlContent(String url) throws ApiException { if(url.equals("try")){ return "thanks"; } if (sUserAgent == null) { throw new ApiException("User-Agent string must be prepared"); } // Create client and set our specific user-agent string HttpClient client = new DefaultHttpClient(); HttpGet request = new HttpGet(url); request.setHeader("User-Agent", sUserAgent); try { HttpResponse response = client.execute(request); // Check if server response is valid StatusLine status = response.getStatusLine(); if (status.getStatusCode() != HTTP_STATUS_OK) { throw new ApiException("Invalid response from server: " + status.toString()); } // Pull content stream from response HttpEntity entity = response.getEntity(); InputStream inputStream = entity.getContent(); ByteArrayOutputStream content = new ByteArrayOutputStream(); // Read response into a buffered stream int readBytes = 0; while ((readBytes = inputStream.read(sBuffer)) != -1) { content.write(sBuffer, 0, readBytes); } // Return result from buffered stream return new String(content.toByteArray()); } catch (IOException e) { throw new ApiException("Problem communicating with API", e); } }

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• error C2512 in precompiled header file?

  - by SoloMael

  I'm having a ridiculously strange problem. When I try to run the program below, there's an error message that says: "error C2512: 'Record' : no appropriate default constructor available". And when I double-click it, it directs me to a precompiled read-only header file named "xmemory0". Do they expect me to change a read-only file? Here's the segment of code in the file it directs me to: void construct(_Ty *_Ptr) { // default construct object at _Ptr ::new ((void *)_Ptr) _Ty(); // directs me to this line } Here's the program: #include <iostream> #include <vector> #include <string> using namespace std; const int NG = 4; // number of scores struct Record { string name; // student name int scores[NG]; double average; // Calculate the average // when the scores are known Record(int s[], double a) { double sum = 0; for(int count = 0; count != NG; count++) { scores[count] = s[count]; sum += scores[count]; } average = a; average = sum / NG; } }; int main() { // Names of the class string names[] = {"Amy Adams", "Bob Barr", "Carla Carr", "Dan Dobbs", "Elena Evans"}; // exam scores according to each student int exams[][NG]= { {98, 87, 93, 88}, {78, 86, 82, 91}, {66, 71, 85, 94}, {72, 63, 77, 69}, {91, 83, 76, 60}}; vector<Record> records(5); return 0; }

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• How to store a public key in a machine-level RSA key container

  - by Andrew Kimball

  I'm having a problem using a machine level RSA key container when storing only the public key of a public/private key pair. The following code creates a public/private pair and extracts the public key from that pair. The pair and the public key are stored in separate key containers. The keys are then obtained from those key containers at which point they should be the same as the keys going into the containers. The code works when CspProviderFlags.UseDefaultKeyContainer is specified for CspParameters.Flags (i.e. the key read back out from the PublicKey container is the same), but when CspProviderFlags.UseMachineKeyStore is specified for CspParameters.Flags the key read back from PublicKey is different. Why is the behaviour different, and what do I need to do differently to retrieve the public key from a machine-level RSA key container? var publicPrivateRsa = new RSACryptoServiceProvider(new CspParameters() { KeyContainerName = "PublicPrivateKey", Flags = CspProviderFlags.UseMachineKeyStore //Flags = CspProviderFlags.UseDefaultKeyContainer } ) { PersistKeyInCsp = true, }; var publicRsa = new RSACryptoServiceProvider(new CspParameters() { KeyContainerName = "PublicKey", Flags = CspProviderFlags.UseMachineKeyStore //Flags = CspProviderFlags.UseDefaultKeyContainer } ) { PersistKeyInCsp = true }; //Export the key. publicRsa.ImportParameters(publicPrivateRsa.ExportParameters(false)); Console.WriteLine(publicRsa.ToXmlString(false)); Console.WriteLine(publicPrivateRsa.ToXmlString(false)); //Dispose those two CSPs. using (publicRsa) { publicRsa.Clear(); } using (publicPrivateRsa) { publicRsa.Clear(); } publicPrivateRsa = new RSACryptoServiceProvider(new CspParameters() { KeyContainerName = "PublicPrivateKey", Flags = CspProviderFlags.UseMachineKeyStore //Flags = CspProviderFlags.UseDefaultKeyContainer } ); publicRsa = new RSACryptoServiceProvider(new CspParameters() { KeyContainerName = "PublicKey", Flags = CspProviderFlags.UseMachineKeyStore //Flags = CspProviderFlags.UseDefaultKeyContainer } ); Console.WriteLine(publicRsa.ToXmlString(false)); Console.WriteLine(publicPrivateRsa.ToXmlString(false)); using (publicRsa) { publicRsa.Clear(); } using (publicPrivateRsa) { publicRsa.Clear(); }

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• Tinyurl API Example - Am i doing it right :D

  - by Paul Weber

  Hi ... we use super-long Hashes for the Registration of new Users in our Application. The Problem is that these Hashes break in some Email Clients - making the Links unusable. I tried implementing the Tinyurl - API, with a simple Call, but i think it times out sometimes ... sometimes the mail does not reach the user. I updated the Code, but now the URL is never converted. Is Tinyurl really so slow or am i doing something wrong? (I mean hey, 5 Seconds is much in this Times) Can anybody recommend me a more reliable service? All my Fault, forgot a false in the fopen. But i will leave this sample of code here, because i often see this sample, wich i think does not work very reliable: return file_get_contents('http://tinyurl.com/api-create.php?url='.$u); This is the - i think fully working sample. I would like to hear about Improvements. static function gettinyurl( $url ) { $context = stream_context_create( array( 'http' => array( 'timeout' => 5 // 5 Seconds should be enough ) ) ); // get tiny url via api-create.php $fp = fopen( 'http://tinyurl.com/api-create.php?url='.$url, 'r', $context); // open (read) api-create.php with long url as get parameter if( $fp ) { // check if open was ok $tinyurl = fgets( $fp ); // read response if( $tinyurl && !empty($tinyurl) ) // check if response is ok $url = $tinyurl; // set response as url fclose( $fp ); // close connection } // return return $url; // return (tiny) url }

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• S3 Backup Memory Usage in Python

  - by danpalmer

  I currently use WebFaction for my hosting with the basic package that gives us 80MB of RAM. This is more than adequate for our needs at the moment, apart from our backups. We do our own backups to S3 once a day. The backup process is this: dump the database, tar.gz all the files into one backup named with the correct date of the backup, upload to S3 using the python library provided by Amazon. Unfortunately, it appears (although I don't know this for certain) that either my code for reading the file or the S3 code is loading the entire file in to memory. As the file is approximately 320MB (for today's backup) it is using about 320MB just for the backup. This causes WebFaction to quit all our processes meaning the backup doesn't happen and our site goes down. So this is the question: Is there any way to not load the whole file in to memory, or are there any other python S3 libraries that are much better with RAM usage. Ideally it needs to be about 60MB at the most! If this can't be done, how can I split the file and upload separate parts? Thanks for your help. This is the section of code (in my backup script) that caused the processes to be quit: filedata = open(filename, 'rb').read() content_type = mimetypes.guess_type(filename)[0] if not content_type: content_type = 'text/plain' print 'Uploading to S3...' response = connection.put(BUCKET_NAME, 'daily/%s' % filename, S3.S3Object(filedata), {'x-amz-acl': 'public-read', 'Content-Type': content_type})

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• How do I recover from pushing a gitosis.conf file with parsing errors due to line breaks?

  - by Kasia

  I have successfully set up gitosis for an Android mirror (containing multiple git repositories). While adding a new .git path following writable= in gitosis.conf I managed to insert a few line breaks. Saved, committed and pushed to server when I received the following parsing error: Traceback (most recent call last): File "/usr/bin/gitosis-run-hook", line 8, in load_entry_point('gitosis==0.2', 'console_scripts', 'gitosis-run-hook')() File "/usr/lib/python2.5/site-packages/gitosis-0.2-py2.5.egg/gitosis/app.py", line 24, in run return app.main() File "/usr/lib/python2.5/site-packages/gitosis-0.2-py2.5.egg/gitosis/app.py", line 38, in main self.handle_args(parser, cfg, options, args) File "/usr/lib/python2.5/site-packages/gitosis-0.2-py2.5.egg/gitosis/run_hook.py", line 75, in handle_args post_update(cfg, git_dir) File "/usr/lib/python2.5/site-packages/gitosis-0.2-py2.5.egg/gitosis/run_hook.py", line 33, in post_update cfg.read(os.path.join(export, '..', 'gitosis.conf')) File "/usr/lib/python2.5/ConfigParser.py", line 267, in read self._read(fp, filename) File "/usr/lib/python2.5/ConfigParser.py", line 490, in _read raise e ConfigParser.ParsingError: File contains parsing errors: ./gitosis-export/../gitosis.conf (...) I have removed the line break and amendend the commit by git commit -m "fix linebreak" --amend However git push still yields the exact same error. It leads me to believe gitosis is preventing me from doing any further pushes. How do I recover from this?

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• Can't download pdf with java

  - by gedemagt

  I'm trying to download a file from http://aula.au.dk/main/document/document.php?action=download&id=%2F%D8velsesvejledning+2012.pdf but it dosen't appear to be a pdf, when i try downloading it with this code import java.io.*; import java.net.*; public class DownloadFile { public static void download(String address, String localFileName) throws IOException { URL url1 = new URL(address); byte[] ba1 = new byte[1024]; int baLength; FileOutputStream fos1 = new FileOutputStream(localFileName); try { // Contacting the URL System.out.print("Connecting to " + url1.toString() + " ... "); URLConnection urlConn = url1.openConnection(); // Checking whether the URL contains a PDF if (!urlConn.getContentType().equalsIgnoreCase("application/pdf")) { System.out.println("FAILED.\n[Sorry. This is not a PDF.]"); } else { try { // Read the PDF from the URL and save to a local file InputStream is1 = url1.openStream(); while ((baLength = is1.read(ba1)) != -1) { fos1.write(ba1, 0, baLength); } fos1.flush(); fos1.close(); is1.close(); } catch (ConnectException ce) { System.out.println("FAILED.\n[" + ce.getMessage() + "]\n"); } } } catch (NullPointerException npe) { System.out.println("FAILED.\n[" + npe.getMessage() + "]\n"); } } } Can you help me out here?

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• RFC: Whitespace's Assembly Mnemonics

  - by Noctis Skytower

  Request For Comment regarding Whitespace's Assembly Mnemonics What follows in a first generation attempt at creating mnemonics for a whitespace assembly language. STACK ===== push number copy copy number swap away away number MATH ==== add sub mul div mod HEAP ==== set get FLOW ==== part label call label goto label zero label less label back exit I/O === ochr oint ichr iint In the interest of making improvements to this small and simple instruction set, this is a second attempt. hold N Push the number onto the stack copy Duplicate the top item on the stack copy N Copy the nth item on the stack (given by the argument) onto the top of the stack swap Swap the top two items on the stack drop Discard the top item on the stack drop N Slide n items off the stack, keeping the top item add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo save Store load Retrieve L: Mark a location in the program call L Call a subroutine goto L Jump unconditionally to a label if=0 L Jump to a label if the top of the stack is zero if<0 L Jump to a label if the top of the stack is negative return End a subroutine and transfer control back to the caller exit End the program print chr Output the character at the top of the stack print int Output the number at the top of the stack input chr Read a character and place it in the location given by the top of the stack input int Read a number and place it in the location given by the top of the stack What is the general consensus on the following revised list for Whitespace's assembly instructions? They definitely come from thinking outside of the box and trying to come up with a better mnemonic set than last time. When the previous python interpreter was written, it was completed over two contiguous, rushed evenings. This rewrite deserves significantly more time now that it is the summer. Of course, the next version of Whitespace (0.4) may have its instructions revised even more, but this is just a redesign of what originally was done in a few hours. Hopefully, the instructions make more sense to those new to programming jargon.

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• SerializationException with custom GenericIdentiy?

  - by MunkiPhD

  I'm trying to implement my own GenericIdentity implementation but keep receiving the following error when it attempts to load the views (I'm using asp.net MVC): System.Runtime.Serialization.SerializationException was unhandled by user code Message="Type is not resolved for member 'OpenIDExtendedIdentity,Training.Web, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'." Source="WebDev.WebHost" I've ended up with the following class: [Serializable] public class OpenIDExtendedIdentity : GenericIdentity { private string _nickName; private int _userId; public OpenIDExtendedIdentity(String name, string nickName, int userId) : base(name, "OpenID") { _nickName = nickName; _userId = userId; } public string NickName { get { return _nickName; } } public int UserID { get { return _userId; } } } In my Global.asax I read a cookie's serialized value into a memory stream and then use that to create my OpenIDExtendedIdentity object. I ended up with this attempt at a solution after countless tries of various sorts. It works correctly up until the point where it attempts to render the views. What I'm essentially attempting to achieve is the ability to do the following (While using the default Role manager from asp.net): User.Identity.UserID User.Identity.NickName ... etc. I've listed some of the sources I've read in my attempt to get this resolved. Some people have reported a Cassini error, but it seems like others have had success implementing this type of custom functionality - thus a boggling of my mind. http://forums.asp.net/p/32497/161775.aspx http://ondotnet.com/pub/a/dotnet/2004/02/02/effectiveformsauth.html http://social.msdn.microsoft.com/Forums/en-US/netfxremoting/thread/e6767ae2-dfbf-445b-9139-93735f1a0f72

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• SQL Server Index cost

  - by yellowstar

  I have read that one of the tradeoffs for adding table indexes in SQL Server is the increased cost of insert/update/delete queries to benefit the performance of select queries. I can conceptually understand what happens in the case of an insert because SQL Server has to write entries into each index matching the new rows, but update and delete are a little more murky to me because I can't quite wrap my head around what the database engine has to do. Let's take DELETE as an example and assume I have the following schema (pardon the pseudo-SQL) TABLE Foo col1 int ,col2 int ,col3 int ,col4 int PRIMARY KEY (col1,col2) INDEX IX_1 col3 INCLUDE col4 Now, if I issue the statement DELETE FROM Foo WHERE col1=12 AND col2 > 34 I understand what the engine must do to update the table (or clustered index if you prefer). The index is set up to make it easy to find the range of rows to be removed and do so. However, at this point it also needs to update IX_1 and the query that I gave it gives no obvious efficient way for the database engine to find the rows to update. Is it forced to do a full index scan at this point? Does the engine read the rows from the clustered index first and generate a smarter internal delete against the index? It might help me to wrap my head around this if I understood better what is going on under the hood, but I guess my real question is this. I have a database that is spending a significant amount of time in delete and I'm trying to figure out what I can do about it. When I display the execution plan for the deletion, it just shows an entry for "Clustered Index Delete" on table Foo which lists in the details section the other indices that need to be updated but I don't get any indication of the relative cost of these other indices. Are they all equal in this case? Is there some way that I can estimate the impact of removing one or more of these indices without having to actually try it?

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• CreateDelegate with unknown types

  - by Giorgi

  Hello, I am trying to create Delegate for reading/writing properties of unknown type of class at runtime. I have a generic class Main<T> and a method which looks like this: Delegate.CreateDelegate(typeof(Func<T, object>), get) where get is a MethodInfo of the property that should be read. The problem is that when the property returns int (I guess this happens for value types) the above code throws ArgumentException because the method cannot be bound. In case of string it works well. To solve the problem I changed the code so that corresponding Delegate type is generated by using MakeGenericType. So now the code is: Type func = typeof(Func<,>); Type generic = func.MakeGenericType(typeof(T), get.ReturnType); var result = Delegate.CreateDelegate(generic, get) The problem now is that the created delegate instance of generic so I have to use DynamicInvoke which would be as slow as using pure reflection to read the field. So my question is why is that the first snippet of code fails with value types. According to MSDN it should work as it says that The return type of a delegate is compatible with the return type of a method if the return type of the method is more restrictive than the return type of the delegate and how to execute the delegate in the second snippet so that it is faster than reflection. Thanks.

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• Choosing between .NET Service Bus Queues vs Azure Queue Service

  - by ChrisV

  Just a quick question regarding an Azure application. If I have a number of Web and Worker roles that need to communicate, documentation says to use the Azure Queue Service. However, I've just read that the new .NET Service Bus now also offers queues. These look to be more powerful as they appear to offer a much more detailed API. Whilst the .NSB looks more interesting it has a couple of issues that make me wary of using it in distributed application. (for example, Queue Expiration... if I cannot guarantee that a queue will be renewed on time I may lose it all!). Has anyone had any experience using either of these two technologies and could give any advice on when to choose one over the other. I suspect that whilst the service bus looks more powerful, as my use case is really just enabling Web/Worker roles to communicate between each other, that the Azure Queue Service is what I'm after. But I'm just really looking for confirmation of that before progamming myself in to a corner :-) Thanks in advance. UPDATE Have read up about the two systems over the break. It defo looks like .NET service bus is more specifically designed for integrating systems rather than providing a general purpose reliable messaging system. Azure Queues are distributed and so reliable and scalable in a way that .NSB queues are not and so more suitable for code hosted within Azure itself. Thanks for the responses.

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• What's the most DRY-appropriate way to execute an SQL command?

  - by Sean U

  I'm looking to figure out the best way to execute a database query using the least amount of boilerplate code. The method suggested in the SqlCommand documentation: private static void ReadOrderData(string connectionString) { string queryString = "SELECT OrderID, CustomerID FROM dbo.Orders;"; using (SqlConnection connection = new SqlConnection(connectionString)) { SqlCommand command = new SqlCommand(queryString, connection); connection.Open(); SqlDataReader reader = command.ExecuteReader(); try { while (reader.Read()) { Console.WriteLine(String.Format("{0}, {1}", reader[0], reader[1])); } } finally { reader.Close(); } } } mostly consists of code that would have to be repeated in every method that interacts with the database. I'm already in the habit of factoring out the establishment of a connection, which would yield code more like the following. (I'm also modifying it so that it returns data, in order to make the example a bit less trivial.) private SQLConnection CreateConnection() { var connection = new SqlConnection(_connectionString); connection.Open(); return connection; } private List<int> ReadOrderData() { using(var connection = CreateConnection()) using(var command = connection.CreateCommand()) { command.CommandText = "SELECT OrderID FROM dbo.Orders;"; using(var reader = command.ExecuteReader()) { var results = new List<int>(); while(reader.Read()) results.Add(reader.GetInt32(0)); return results; } } } That's an improvement, but there's still enough boilerplate to nag at me. Can this be reduced further? In particular, I'd like to do something about the first two lines of the procedure. I don't feel like the method should be in charge of creating the SqlCommand. It's a tiny piece of repetition as it is in the example, but it seems to grow if transactions are being managed manually or timeouts are being altered or anything like that.

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• Core principles, rules, and habits for CS students

  - by Asad Butt

  No doubt there is a lot to read on blogs, in books, and on Stack Overflow, but can we identify some guidelines for CS students to use while studying? For me these are: Finish your course books early and read 4-5 times more material relative to your course work. Programming is the one of the fastest evolving professions. Follow the blogs on a daily basis for the latest updates, news, and technologies. Instead of relying on assignments and exams, do at least one extra, non-graded, small to medium-sized project for every programming course. Fight hard for internships or work placements even if they are unpaid, since 3 months of work 1 year at college. Practice everything, every possible and impossible way. Try doing every bit of your assignments project yourself; i.e. fight for every inch. Rely on documentation as the first source for help and samples, Google, and online forums as the last source. Participate often in online communities and forums to learn the best possible approach for every solution to your problem. (After doing your bit.) Make testing one of your habits as it is getting more important everyday in programming. Make writing one of your habits. Write something productive once or twice a week and publish it.

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• Java - encrypt / decrypt user name and password from a configuration file

  - by nzpcmad

  We are busy developing a Java web service for a client. There are two possible choices: Store the encrypted user name / password on the web service client. Read from a config. file on the client side, decrypt and send. Store the encrypted user name / password on the web server. Read from a config. file on the web server, decrypt and use in the web service. The user name / password is used by the web service to access a third-party application. The client already has classes that provide this functionality but this approach involves sending the user name / password in the clear (albeit within the intranet). They would prefer storing the info. within the web service but don't really want to pay for something they already have. (Security is not a big consideration because it's only within their intranet). So we need something quick and easy in Java. Any recommendations? The server is Tomkat 5.5. The web service is Axis2. What encrypt / decrypt package should we use? What about a key store? What configuration mechanism should we use? Will this be easy to deploy?

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• LINQtoSQL Custom Constructor off Partial Class?

  - by sah302

  Hi all, I read this question here: http://stackoverflow.com/questions/82409/is-there-a-way-to-override-the-empty-constructor-in-a-class-generated-by-linqtosq Typically my constructor would look like: public User(String username, String password, String email, DateTime birthday, Char gender) { this.Id = Guid.NewGuid(); this.DateCreated = this.DateModified = DateTime.Now; this.Username = username; this.Password = password; this.Email = email; this.Birthday = birthday; this.Gender = gender; } However, as read in that question, you want to use partial method OnCreated() instead to assign values and not overwrite the default constructor. Okay so I got this : partial void OnCreated() { this.Id = Guid.NewGuid(); this.DateCreated = this.DateModified = DateTime.Now; this.Username = username; this.Password = password; this.Email = email; this.Birthday = birthday; this.Gender = gender; } However, this gives me two errors: Partial Methods must be declared private. Partial Methods must have empty method bodies. Alright I change it to Private Sub OnCreated() to remove both of those errors. However I am still stuck with...how can I pass it values as I would with a normal custom constructor? Also I am doing this in VB (converted it since I know most know/prefer C#), so would that have an affect on this?

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• mprotect - how aligning to multiple of pagesize works?

  - by user299988

  Hi, I am not understanding the 'aligning allocated memory' part from the mprotect usage. I am referring to the code example given on http://linux.die.net/man/2/mprotect char *p; char c; /* Allocate a buffer; it will have the default protection of PROT_READ|PROT_WRITE. */ p = malloc(1024+PAGESIZE-1); if (!p) { perror("Couldn't malloc(1024)"); exit(errno); } /* Align to a multiple of PAGESIZE, assumed to be a power of two */ p = (char *)(((int) p + PAGESIZE-1) & ~(PAGESIZE-1)); c = p[666]; /* Read; ok */ p[666] = 42; /* Write; ok */ /* Mark the buffer read-only. */ if (mprotect(p, 1024, PROT_READ)) { perror("Couldn't mprotect"); exit(errno); } For my understanding, I tried using a PAGESIZE of 16, and 0010 as address of p. I ended up getting 0001 as the result of (((int) p + PAGESIZE-1) & ~(PAGESIZE-1)). Could you please clarify how this whole 'alignment' works? Thanks,

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• Looking for detailed explanation of Hibernate UserType methods for mutable objects

  - by Tom

  I am creating a custom UserType class in Hibernate. The specific case is for an HL7v3 clinical document (I work in health IT). It is a mutable object and most of the documentation around the Hibernate UserType interface seems to center around immutable types. I want a better understanding of how and when the interface methods are used, specifically: assemble - why two parameters (one Serializable, one Object)? What is the use case for this method? disassemble - should I just implement this method to return a serializable form (e.g. String representation)? When and how is this method invoked? equals - is this for update? read? contention? dirty reads? What are the consequences of simply returning false in most cases? replace - I really don't understand where the three Object parameters come from, when this method is invoked, and what Hibernate expects to return, or how that return value is used. Any pointers would be appreciated. I've searched and read all I can find on the subject, but have not found much documentation at all explaining how these methods are used for mutable objects.

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