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  • ADO/SQL Server: What is the error code for "timeout expired"?

    - by Ian Boyd
    i'm trying to trap a "timeout expired" error from ADO. When a timeout happens, ADO returns: Number: 0x80040E31 (DB_E_ABORTLIMITREACHED in oledberr.h) SQLState: HYT00 NativeError: 0 The NativeError of zero makes sense, since the timeout is not a function of the database engine (i.e. SQL Server), but of ADO's internal timeout mechanism. The Number (i.e. the COM hresult) looks useful, but the definition of DB_E_ABORTLIMITREACHED in oledberr.h says: Execution stopped because a resource limit was reached. No results were returned. This error could apply to things besides "timeout expired" (some potentially server-side), such as a governor that limits: CPU usage I/O reads/writes network bandwidth and stops a query. The final useful piece is SQLState, which is a database-independent error code system. Unfortunately the only reference for SQLState error codes i can find have no mention of HYT00. What to do? What do do? Note: i can't trust 0x80040E31 (DB_E_ABORTLIMITREACHED) to mean "timeout expired", anymore than i could trust 0x80004005 (E_UNSPECIFIED_ERROR) to mean "Transaction was deadlocked on lock resources with another process and has been chosen as the deadlock victim". My pseudo-question becomes: does anyone have documentation on what the SQLState "HYT000" means? And my real question still remains: How can i specifically trap an ADO timeout expired exception thrown by ADO? Gotta love the questions where the developer is trying to "do the right thing", but nobody knows how to do the right thing. Also gotta love how googling for DB_E_ABORTLIMITREACHED and this question is #9, with MSDN nowhere to be found. Update 3 From the OLEdb ICommand.Execute reference: DB_E_ABORTLIMITREACHED Execution has been aborted because a resource limit has been reached. For example, a query timed out. No results have been returned. "For example", meaning not an exhaustive list.

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  • OutOfMemory during paging

    - by Tony
    Hi I am using ObjectDataSource, ListView, CustomPaging If the total number of rows is too big, I got OutOfMemory exception, it seems that it caused by some array, I don't get it, because total number of rows should never make any array to be filled with elements, the page size do!! This is the logger. ****EXCEPTION # 3 : 4/30/2010 9:43:07 PM System.Web.HttpUnhandledException: Exception of type 'System.Web.HttpUnhandledException' was thrown. --- System.OutOfMemoryException: Exception of type 'System.OutOfMemoryException' was thrown. at System.Web.UI.WebControls.ListView.CreateChildControls() at System.Web.UI.Control.EnsureChildControls() at System.Web.UI.WebControls.ListView.get_Controls() at System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) at System.Web.UI.Control.LoadViewStateRecursive(Object savedState) at System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) at System.Web.UI.Control.LoadViewStateRecursive(Object savedState) at System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) at System.Web.UI.Control.LoadViewStateRecursive(Object savedState) at System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) at System.Web.UI.Control.LoadViewStateRecursive(Object savedState) at System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) at System.Web.UI.Control.LoadViewStateRecursive(Object savedState) at System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) at System.Web.UI.Control.LoadViewStateRecursive(Object savedState) at System.Web.UI.Page.LoadAllState() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) --- End of inner exception stack trace --- at System.Web.UI.Page.HandleError(Exception e) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.ProcessRequest() at System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context) at System.Web.UI.Page.ProcessRequest(HttpContext context) at ASP.default_aspx.ProcessRequest(HttpContext context) in c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\flickrdemo\15752207\c63ea96c\App_Web__8yxn9sb.0.cs:line 0 at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

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  • Calling unmanaged code from within C#

    - by Charles Gargent
    I am trying to use a dll in my c# program but I just cant seem to get it to work. I have made a test app shown below. The return value is 0, however it does not actually do what it is supposed to do. Whereas the following command does work: rundll32 cmproxy.dll,SetProxy /source_filename proxy-1.txt /backup_filename roxy.bak /DialRasEntry NULL /TunnelRasEntry DSLVPN /Profile "C:\Documents and ettings\Administrator\Application Data\Microsoft\Network\Connections\Cm\dslvpn.cmp" Code: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Security.Cryptography; using System.Runtime.InteropServices; using System.Net; using WUApiLib; namespace nac { class Program { [DllImport("cmproxy.dll", CharSet = CharSet.Unicode)] static extern int SetProxy(string cmdLine); static void Main(string[] args) { string cmdLine = @"/source_filename proxy-1.txt /backup_filename proxy.bak /DialRasEntry NULL /TunnelRasEntry DSLVPN /Profile ""C:\Documents and Settings\Administrator\Application Data\Microsoft\Network\Connections\Cm\dslvpn.cmp"""; Console.WriteLine(SetProxy(cmdLine)); } } } Here is the contents of the dumpbin /exports command File Type: DLL Section contains the following exports for cmproxy.dll 00000000 characteristics 3E7FEF8C time date stamp Tue Mar 25 05:56:28 2003 0.00 version 1 ordinal base 1 number of functions 1 number of names ordinal hint RVA name 1 0 00001B68 SetProxy Summary 1000 .data 1000 .reloc 1000 .rsrc 2000 .text When this works it sets the proxy server for a VPN connection.

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  • Code bacteria: evolving mathematical behavior

    - by Stefano Borini
    It would not be my intention to put a link on my blog, but I don't have any other method to clarify what I really mean. The article is quite long, and it's in three parts (1,2,3), but if you are curious, it's worth the reading. A long time ago (5 years, at least) I programmed a python program which generated "mathematical bacteria". These bacteria are python objects with a simple opcode-based genetic code. You can feed them with a number and they return a number, according to the execution of their code. I generate their genetic codes at random, and apply an environmental selection to those objects producing a result similar to a predefined expected value. Then I let them duplicate, introduce mutations, and evolve them. The result is quite interesting, as their genetic code basically learns how to solve simple equations, even for values different for the training dataset. Now, this thing is just a toy. I had time to waste and I wanted to satisfy my curiosity. however, I assume that something, in terms of research, has been made... I am reinventing the wheel here, I hope. Are you aware of more serious attempts at creating in-silico bacteria like the one I programmed? Please note that this is not really "genetic algorithms". Genetic algorithms is when you use evolution/selection to improve a vector of parameters against a given scoring function. This is kind of different. I optimize the code, not the parameters, against a given scoring function.

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  • Real benefits of tcp TIME-WAIT and implications in production environment

    - by user64204
    SOME THEORY I've been doing some reading on tcp TIME-WAIT (here and there) and what I read is that it's a value set to 2 x MSL (maximum segment life) which keeps a connection in the "connection table" for a while to guarantee that, "before your allowed to create a connection with the same tuple, all the packets belonging to previous incarnations of that tuple will be dead". Since segments received (apart from SYN under specific circumstances) while a connection is either in TIME-WAIT or no longer existing would be discarded, why not close the connection right away? Q1: Is it because there is less processing involved in dealing with segments from old connections and less processing to create a new connection on the same tuple when in TIME-WAIT (i.e. are there performance benefits)? If the above explanation doesn't stand, the only reason I see the TIME-WAIT being useful would be if a client sends a SYN for a connection before it sends remaining segments for an old connection on the same tuple in which case the receiver would re-open the connection but then get bad segments and and would have to terminate it. Q2: Is this analysis correct? Q3: Are there other benefits to using TIME-WAIT? SOME PRACTICE I've been looking at the munin graphs on a production server that I administrate. Here is one: As you can see there are more connections in TIME-WAIT than ESTABLISHED, around twice as many most of the time, on some occasions four times as many. Q4: Does this have an impact on performance? Q5: If so, is it wise/recommended to reduce the TIME-WAIT value (and what to)? Q6: Is this ratio of TIME-WAIT / ESTABLISHED connections normal? Could this be related to malicious connection attempts?

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  • Convert rank-per-candidate format to OpenSTV BLT format

    - by kibibu
    I recently gathered, using a questionnaire, a set of opinions on the importance of various software components. Figuring that some form of Condorcet voting method would be the best way to obtain an overall rank, I opted to use OpenSTV to analyze it. My data is in tabular format, space delimited, and looks more or less like: A B C D E F G # Candidates 5 2 4 3 7 6 1 # First ballot. G is ranked first, and E is ranked 7th 4 2 6 5 1 7 3 # Second ballot etc In this format, the number indicates the rank and the sequence order indicates the candidate. Each "candidate" has a rank (required) from 1 to 7, where a 1 means most important and a 7 means least important. No duplicates are allowed. This format struck me as the most natural way to represent the output, being a direct representation of the ballot format. The OpenSTV/BLT format uses a different method of representing the same info, conceptually as follows: G B D C A F E # Again, G is ranked first and E is ranked 7th E B G A D C F # etc The actual numeric file format uses the (1-based) index of the candidate, rather than the label, and so is more like: 7 2 4 3 1 6 5 # Same ballots as before. 5 2 7 1 4 3 6 # A -> 1, G -> 7 In this format, the number indicates the candidate, and the sequence order indicates the rank. The actual, real, BLT format also includes a leading weight and a following zero to indicate the end of each ballot, which I don't care too much about for this. My question is, what is the most elegant way to convert from the first format to the (numeric) second?

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  • Sort and limit queryset by comment count and date using queryset.extra() (django)

    - by thornomad
    I am trying to sort/narrow a queryset of objects based on the number of comments each object has as well as by the timeframe during which the comments were posted. Am using a queryset.extra() method (using django_comments which utilizes generic foreign keys). I got the idea for using queryset.extra() (and the code) from here. This is a follow-up question to my initial question yesterday (which shows I am making some progress). Current Code: What I have so far works in that it will sort by the number of comments; however, I want to extend the functionality and also be able to pass a time frame argument (eg, 7 days) and return an ordered list of the most commented posts in that time frame. Here is what my view looks like with the basic functionality in tact: import datetime from django.contrib.comments.models import Comment from django.contrib.contenttypes.models import ContentType from django.db.models import Count, Sum from django.views.generic.list_detail import object_list def custom_object_list(request, queryset, *args, **kwargs): '''Extending the list_detail.object_list to allow some sorting. Example: http://example.com/video?sort_by=comments&days=7 Would get a list of the videos sorted by most comments in the last seven days. ''' try: # this is where I started working on the date business ... days = int(request.GET.get('days', None)) period = datetime.datetime.utcnow() - datetime.timedelta(days=int(days)) except (ValueError, TypeError): days = None period = None sort_by = request.GET.get('sort_by', None) ctype = ContentType.objects.get_for_model(queryset.model) if sort_by == 'comments': queryset = queryset.extra(select={ 'count' : """ SELECT COUNT(*) AS comment_count FROM django_comments WHERE content_type_id=%s AND object_pk=%s.%s """ % ( ctype.pk, queryset.model._meta.db_table, queryset.model._meta.pk.name ), }, order_by=['-count']).order_by('-count', '-created') return object_list(request, queryset, *args, **kwargs) What I've Tried: I am not well versed in SQL but I did try just to add another WHERE criteria by hand to see if I could make some progress: SELECT COUNT(*) AS comment_count FROM django_comments WHERE content_type_id=%s AND object_pk=%s.%s AND submit_date='2010-05-01 12:00:00' But that didn't do anything except mess around with my sort order. Any ideas on how I can add this extra layer of functionality? Thanks for any help or insight.

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  • conditional selection of decimal-format in xslt

    - by Jose L Martinez-Avial
    Hi all, I'm trying to modify the decimal-format of a stylesheet based on certain information of an XML. More exaclty, I've a XML like this <?xml version="1.0" encoding="ISO-8859-1"?> <REPORT> <LANGUAGE>2</LANGUAGE> <MYVALUE>123456.78</MYVALUE> </REPORT> I'm trying to define the decimal format as european if the language is 2, and default otherwse. So I've created the following template <xsl:template match="REPORT"> <xsl:if test="$language=2"> <xsl:decimal-format decimal-separator=',' grouping-separator='.' /> </xsl:if> <xsl:value-of select ="format-number(MYVALUE,'###.###,00')"/> </xsl:template> So it shows the number in european format or in standard format. But I'm getting the following error xsl:decimal-format is not allowed in this position in the stylesheet! If I try to put the decimal-format outside the template, then I get the message that the xsl:if is not allowed in this position in the sthylsheet. How can I change the decimal-format based in the XML? Thanks Jose

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  • Creating dynamic jQuery tooltips for dynamic content

    - by Mel
    I'm using the qTip jQuery plugin to create tooltips for a set of links. Two problems: How do I create a set of tooltips for three dynamically generated links where the content of the tooltip will also be dynamic: a href="books.cfm?bookID=11"Book One a href="books.cfm?bookID=22"Book Two a href="books.cfm?bookID=33"Book Three I would like to create a tooltip for each link. Each tooltip will then load details about each book. Thus I must pass the bookID to the tooltip: $('#catalog a[href]').each(function() { $(this).qtip( { content: { URL: 'cfcs/viewbooks.cfc?method=bookDetails', data: { bookID: <cfoutput>#indexView.bookID#</cfoutput> }, method: 'get' } }); }); Unfortunately the above code is not working correctly. I've gotten it to work when I've used a static 'bookID' instead of a dynamically generated number. Even when it does work (by using a static number for 'bookID', I can't format the data correctly. It comes back as a query result, or a bunch of text strings. Should I send back the results as HTML? Unsure. PS: I am an absolute NOVICE to Javascript and jQuery, so please try not to be as technical. Many thanks!

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  • WPF Grid Column MaxWidth not enforced

    - by Trevor Hartman
    This problem stems from not being able to get my TextBlock to wrap. Basically as a last-ditch attempt I am setting MaxWidth on my container grid's columns. I was surprised to find that my child label and textbox still do whatever they want (bad children, BAD) and are not limited by my grid column's MaxWidth="200". What I'm really trying to do is let my TextBlock fill available width and wrap if necessary. So far after trying many variations of HorizontalAlignment="Stretch" on every known parent in the universe, nothing works, except setting an explicit MaxWidth="400" or whatever number on the TextBlock. This is not good because I need the TextBlock to fill available width, not be limited by some fixed number. Thanks! <ItemsControl> <ItemsControl.ItemsPanel> <ItemsPanelTemplate> <StackPanel /> </ItemsPanelTemplate> </ItemsControl.ItemsPanel> <ItemsControl.ItemTemplate> <DataTemplate> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition MaxWidth="200" SharedSizeGroup="A" /> <ColumnDefinition MaxWidth="200" SharedSizeGroup="B" /> </Grid.ColumnDefinitions> <Label VerticalAlignment="Top" Margin="0 5 0 0" Grid.Column="0" Style="{StaticResource LabelStyle}" Width="Auto" Content="{Binding Value.Summary}" /> <TextBlock Grid.Column="1" Margin="5,8,5,8" FontWeight="Normal" Background="AliceBlue" Foreground="Black" Text="{Binding Value.Description}" HorizontalAlignment="Stretch" TextWrapping="Wrap" Height="Auto" /> </Grid> </DataTemplate> </ItemsControl.ItemTemplate> </ItemsControl>

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  • Problem with writing a hexadecimal string

    - by quilby
    Here is my code /* gcc -c -Wall -g main.c gcc -g -lm -o main main.o */ #include <stdlib.h> #include <stdio.h> #include <string.h> void stringToHex(const char* string, char* hex) { int i = 0; for(i = 0; i < strlen(string)/2; i++) { printf("s%x", string[2*i]); //for debugging sprintf(&hex[i], "%x", string[2*i]); printf("h%x\n", hex[i]); //for debugging } } void writeHex(char* hex, int length, FILE* file, long position) { fseek(file, position, SEEK_SET); fwrite(hex, sizeof(char), length, file); } int main(int argc, char** argv) { FILE* pic = fopen("hi.bmp", "w+b"); const char* string = "f2"; char hex[strlen(string)/2]; stringToHex(string, hex); writeHex(hex, strlen(string)/2, pic, 0); fclose(pic); return 0; } I want it to save the hexadecimal number 0xf2 to a file (later I will have to write bigger/longer numbers though). The program prints out - s66h36 And when I use hexedit to view the file I see the number '36' in it. Why is my code not working? Thanks!

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  • How close can I get C# to the performance of C++ for small intensive tasks?

    - by SLC
    I was thinking about the speed difference of C++ to C# being mostly about C# compiling to byte-code that is taken in by the JIT compiler (is that correct?) and all the checks C# does. I notice that it is possible to turn a lot of these functions off, both in the compile options, and possibly through using the unsafe keyword as unsafe code is not verifiable by the common language runtime. Therefore if you were to write a simple console application in both languages, that flipped an imaginary coin an infinite number of times and displayed the results to the screen every 10,000 or so iterations, how much speed difference would there be? I chose this because it's a very simple program. I'd like to test this but I don't know C++ or have the tools to compile it. This is my C# version though: static void Main(string[] args) { unsafe { Random rnd = new Random(); int heads = 0, tails = 0; while (true) { if (rnd.NextDouble() > 0.5) heads++; else tails++; if ((heads + tails) % 1000000 == 0) Console.WriteLine("Heads: {0} Tails: {1}", heads, tails); } } } Is the difference enough to warrant deliberately compiling sections of code "unsafe" or into DLLs that do not have some of the compile options like overflow checking enabled? Or does it go the other way, where it would be beneficial to compile sections in C++? I'm sure interop speed comes into play too then. To avoid subjectivity, I reiterate the specific parts of this question as: Does C# have a performance boost from using unsafe code? Do the compile options such as disabling overflow checking boost performance, and do they affect unsafe code? Would the program above be faster in C++ or negligably different? Is it worth compiling long intensive number-crunching tasks in a language such as C++ or using /unsafe for a bonus? Less subjectively, could I complete an intensive operation faster by doing this?

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  • ASIHTTPRequest wrapper usage for Macs

    - by Rob
    I am trying to apply the ASIHTTPRequest wrapper to a very basic Objective C program. I have already copied over the necessary files into my program and after giving myself an extreme headache trying to figure out how it works through their website I thought I would post a question on here. The files copied over were: ASIHTTPRequestConfig.h ASIHTTPRequestDelegate.h ASIProgressDelegate.h ASIInputStream.h ASIInputStream.m ASIHTTPRequest.h ASIHTTPRequest.m ASIFormDataRequest.h ASIFormDataRequest.m My program is very basic: #import <Foundation/Foundation.h> int main (int argc, const char * argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; // Defining the various variables. char firstName[20]; char lastName[20]; char rank[5]; int leaveAccrued; int leaveRequested; // User Input. NSLog (@"Please input First Name:"); scanf("%s", &firstName); NSLog (@"Please input Last Name:"); scanf("%s", &lastName); NSLog (@"Please input Rank:"); scanf("%s", &rank); NSLog (@"Please input the number leave days you have accrued:"); scanf("%i", &leaveAccrued); NSLog (@"Please input the number of leave days you are requesting:"); scanf("%i", &leaveRequested); // Print results. NSLog (@"Name: %s %s", firstName, lastName); NSLog (@"Rank: %s", rank); NSLog (@"Leave Accrued: %i", leaveAccrued); NSLog (@"Leave Requested: %i", leaveRequested); [pool drain]; return 0; } How do I utilize the wrapper to export these 5 basic variables to a web server via an http request?

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  • cgi.FieldStorage always empty - never returns POSTed form Data

    - by Dan Carlson
    This problem is probably embarrassingly simple. I'm trying to give python a spin. I thought a good way to start doing that would be to create a simple cgi script to process some form data and do some magic. My python script is executed properly by apache using mod_python, and will print out whatever I want it to print out. My only problem is that cgi.FieldStorage() is always empty. I've tried using both POST and GET. Each trial I fill out both form fields. <form action="pythonScript.py" method="POST" name="ARGH"> <input name="TaskName" type="text" /> <input name="TaskNumber" type="text" /> <input type="submit" /> </form> If I change the form to point to a perl script it reports the form data properly. The python page always gives me the same result: number of keys: 0 #!/usr/bin/python import cgi def index(req): pageContent = """<html><head><title>A page from""" pageContent += """Python</title></head><body>""" form = cgi.FieldStorage() keys = form.keys() keys.sort() pageContent += "<br />number of keys: "+str(len(keys)) for key in keys: pageContent += fieldStorage[ key ].value pageContent += """</body></html>""" return pageContent I'm using Python 2.5.2 and Apache/2.2.3. This is what's in my apache conf file (and my script is in /var/www/python): <Directory /var/www/python/> Options FollowSymLinks +ExecCGI Order allow,deny allow from all AddHandler mod_python .py PythonHandler mod_python.publisher </Directory>

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  • Precision of cos(atan2(y,x)) versus using complex <double>, C++

    - by Ivan
    Hi all, I'm writing some coordinate transformations (more specifically the Joukoswky Transform, Wikipedia Joukowsky Transform), and I'm interested in performance, but of course precision. I'm trying to do the coordinate transformations in two ways: 1) Calculating the real and complex parts in separate, using double precision, as below: double r2 = chi.x*chi.x + chi.y*chi.y; //double sq = pow(r2,-0.5*n) + pow(r2,0.5*n); //slow!!! double sq = sqrt(r2); //way faster! double co = cos(atan2(chi.y,chi.x)); double si = sin(atan2(chi.y,chi.x)); Z.x = 0.5*(co*sq + co/sq); Z.y = 0.5*si*sq; where chi and Z are simple structures with double x and y as members. 2) Using complex : Z = 0.5 * (chi + (1.0 / chi)); Where Z and chi are complex . There interesting part is that indeed the case 1) is faster (about 20%), but the precision is bad, giving error in the third decimal number after the comma after the inverse transform, while the complex gives back the exact number. So, the problem is on the cos(atan2), sin(atan2)? But if it is, how the complex handles that? Thanks!

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  • If attacker has original data and encrypted data, can they determine the passphrase?

    - by Brad Cupit
    If an attacker has several distinct items (for example: e-mail addresses) and knows the encrypted value of each item, can the attacker more easily determine the secret passphrase used to encrypt those items? Meaning, can they determine the passphrase without resorting to brute force? This question may sound strange, so let me provide a use-case: User signs up to a site with their e-mail address Server sends that e-mail address a confirmation URL (for example: https://my.app.com/confirmEmailAddress/bill%40yahoo.com) Attacker can guess the confirmation URL and therefore can sign up with someone else's e-mail address, and 'confirm' it without ever having to sign in to that person's e-mail account and see the confirmation URL. This is a problem. Instead of sending the e-mail address plain text in the URL, we'll send it encrypted by a secret passphrase. (I know the attacker could still intercept the e-mail sent by the server, since e-mail are plain text, but bear with me here.) If an attacker then signs up with multiple free e-mail accounts and sees multiple URLs, each with the corresponding encrypted e-mail address, could the attacker more easily determine the passphrase used for encryption? Alternative Solution I could instead send a random number or one-way hash of their e-mail address (plus random salt). This eliminates storing the secret passphrase, but it means I need to store that random number/hash in the database. The original approach above does not require storage in the database. I'm leaning towards the the one-way-hash-stored-in-the-db, but I still would like to know the answer: does having multiple unencrypted e-mail addresses and their encrypted counterparts make it easier to determine the passphrase used?

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  • GPIB connection to external device using MATLAB

    - by hkf
    Is there a way to establish a GPIB connection using MATLAB without the instrument control Tool box? (I don't have it). Also is there a way for MATLAB to know what the external device's RS232 parameter values are ( Baud rate, stop bit etc..). For the RS232 connection I have the following code: % This function is meant to send commands to Potentiostat Model 263A. % A run includes turning the cell on, reading current for time t1, turning % the cell off, waiting for time t2. % t1 is the duration [secs] for which the Potentiostat must run (cell is on) % t2 is the duration [secs] to on after off % n is the number of runs % port is the serial port name such as COM1 function [s] = Potentiostat_control(t1,t2,n) port = input('type port name such as COM1', 's') s = serial(port); set(s,'BaudRate', 9600, 'DataBits', 8, 'Parity', 'even', 'StopBits', 2 ,'Terminator', 'CR/LF'); fopen(s) %fprintf(s,'RS232?') disp(['Total runs requested = ' num2str(n)]) disp('i denotes number of runs executed so far..'); for i=1:n i %data1 = query(s, '*IDN?') fprintf(s,'%s','CELL 1'); % sends the command 'CELL 1' %fprintf(s,'%s','READI'); pause(t1); fprintf(s,'%s','CELL 0'); %fprintf(s,'%s','CLEAR'); pause(t2); end fclose(s)

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  • How do I exclude data from local table schema_migrations from being pushed to Heroku DB?

    - by Thierry Lam
    I was able to push my Ruby on Rails app with MySQL(local dev) to the Heroku server along with migrating my model with the command heroku rake db:migrate. I have also read the documentation on Database Import/Export. Is that doc referring to pushing actual data from my local dev DB to whichever Heroku's DB? Do I need to modify anything in the file database.yml to make it happen? I ran the following command: heroku db:push and I am getting the error: Sending data 2 tables, 3 records !!! Caught Server Exception | ETA: --:--:-- Taps Server Error: PGError ERROR: duplicate key value violates unique constraint "unique_schema_migrations" I have 2 tables, one I create for my app and the other schema_migrations. The total number of entries among the 2 tables is 3. I'm also printing the number of entries I have in the table I have created and it's showing 0. Any ideas what I might be missing or what I am doing wrong? EDIT: I figured out the above, Heroku's DB already have schema_migrations the moment I ran migrate. New question: Does anyone know how I can exclude data from a specific table from being pushed to Heroku DB. The table to exclude in this case will be schema_migrations. Not so good solution: I googled around and someone else was having the same issue. He suggested naming the schema_migrations table to zschema_migrations. In this way data from the other tables will be pushed properly until it fails on the last table. It's a pretty bad solution but will do for the time being. A better solution will be to use an existing Rails command which can reset a specific table from a database. I don't think Rake can do that.

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  • What is the best way to iterate over a large result set in JDBC/iBatis 3?

    - by paul_sns
    We're trying to iterate over a large number of rows from the database and convert those into objects. Behavior will be as follows: Result will be sorted by sequence id, a new object will be created when sequence id changes. The object created will be sent to an external service and will sometimes have to wait before sending another one (which means the next set of data will not be immediately used) We already have invested code in iBatis 3 so an iBatis solution will be the best approach for us (we've tried using RowBounds but haven't seen how it does the iteration under the hood). We'd like to balance minimizing memory usage and reducing number of DB trips. We're also open to pure JDBC approach but we'd like the solution to work on different databases. UPDATE: We need to make as few calls to DB as possible (1 call would be the ideal scenario) while also preventing the application to use too much memory. Are there any other solutions out there for this type of problem may it be pure JDBC or any other technology? Thanks and hope to hear your insights on this.

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  • Managing Instances in Python

    - by BeensTheGreat
    Hello, I am new to Python and this is my first time asking a stackOverflow question, but a long time reader. I am working on a simple card based game but am having trouble managing instances of my Hand class. If you look below you can see that the hand class is a simple container for cards(which are just int values) and each Player class contains a hand class. However, whenever I create multiple instances of my Player class they all seem to manipulate a single instance of the Hand class. From my experience in C and Java it seems that I am somehow making my Hand class static. If anyone could help with this problem I would appreciate it greatly. Thank you, Thad To clarify: An example of this situation would be p = player.Player() p1 = player.Player() p.recieveCard(15) p1.recieveCard(21) p.viewHand() which would result in: [15,21] even though only one card was added to p Hand class: class Hand: index = 0 cards = [] #Collections of cards #Constructor def __init__(self): self.index self.cards def addCard(self, card): """Adds a card to current hand""" self.cards.append(card) return card def discardCard(self, card): """Discards a card from current hand""" self.cards.remove(card) return card def viewCards(self): """Returns a collection of cards""" return self.cards def fold(self): """Folds the current hand""" temp = self.cards self.cards = [] return temp Player Class import hand class Player: name = "" position = 0 chips = 0 dealer = 0 pHand = [] def __init__ (self, nm, pos, buyIn, deal): self.name = nm self.position = pos self.chips = buyIn self.dealer = deal self.pHand = hand.Hand() return def recieveCard(self, card): """Recieve card from the dealer""" self.pHand.addCard(card) return card def discardCard(self, card): """Throw away a card""" self.pHand.discardCard(card) return card def viewHand(self): """View the players hand""" return self.pHand.viewCards() def getChips(self): """Get the number of chips the player currently holds""" return self.chips def setChips(self, chip): """Sets the number of chips the player holds""" self.chips = chip return def makeDealer(self): """Makes this player the dealer""" self.dealer = 1 return def notDealer(self): """Makes this player not the dealer""" self.dealer = 0 return def isDealer(self): """Returns flag wether this player is the dealer""" return self.dealer def getPosition(self): """Returns position of the player""" return self.position def getName(self): """Returns name of the player""" return self.name

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  • Refresher on Java classes in separate files

    - by JohnFaig
    I need a refresher on moving classes from one file into two files. My sample code is in one file called "external_class_file_main". The program runs fine and the code is shown below: Public class external_class_file_main { public static int get_a_random_number (int min, int max) { int n; n = (int)(Math.random() * (max - min +1)) + min; return (n); } public static void main(String[] args) { int r; System.out.println("Program starting..."); r = get_a_random_number (1, 5); System.out.println("random number = " + r); System.out.println("Program ending..."); } } I move the get_a_random_number class to a separate file called "external_class_file". When I do this, I get the following error: Exception in thread "main" java.lang.Error: Unresolved compilation problem: The method get_a_random_number(int, int) is undefined for the type external_class_file_main at external_class_file_main.main(external_class_file_main.java:20) The "external_class_file_main" now contains: public class external_class_file_main { public static void main(String[] args) { int r; System.out.println("Program starting..."); r = get_a_random_number (1, 5); System.out.println("random number = " + r); System.out.println("Program ending..."); } } The "external_class_file" now contains: public class external_class_file { public static int get_a_random_number (int min, int max) { int n; n = (int)(Math.random() * (max - min +1)) + min; return (n); } }

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  • LINQ to XML contents of child records.

    - by Fossaw
    I have this LINQ to XML enquiry... var Records = from Item in XDoc.Root.Elements("Item") where (string)Item.Element("ItemNumber") == item.ID.ToString select Item; ... where ItemNumber is a reference number used in the XML, (originally written by this program but manually edited by "others"), and item.ID is the database version of the same thing. The query executes, and I can test for the number of entries in the result fine... if (Records.Count() < 1) ... you get the idea. I have established that there is only one record. Each Item has several child fields. I want to test the values of the child fields are reasonable before passing them on to the database update sub-system. The XML is produced by the program, but edited by users, so I need to really check what is coming back. So I tried... if (DB_English.ToString() != Records.Elements("English").ToString()) ... DB_English is from the database, but the XML in Records, does not contain the contents of that field, it contains... System.Xml.Linq.Extensions+<GetElements>d__29`1[System.Xml.Linq.XElement] ... so, how do I get the value of this element in the XML file? I need to check the field in the XML has not been altered, (the manual editors of this data file are not potentially 100% reliable).

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  • Modeling multiple polymorphic relationships using Hibernate

    - by f-potter
    Ruby on Rails has polymorphic relations which are really useful for implementing functionality such as commenting, tagging and rating to name a few. We can have a comment, tag or rating class which has a many to one polymorphic relationship with a commentable, taggable and rateable object. Also, a given domain object can choose to implement any combination of such relations. So, it can for example be commentable, taggable and rateable at the same time. I couldn't think up of a straightforward way to duplicate this functionality in Hibernate. Ideally, there would be a Comment class which will have a many to one relationship with a Commentable class and a Commentable class will conversely have a one to many relationship with Comments. It will be ideal if the concrete domain classes can inherit from a number of such classes, say Commentable and Taggable. Things seem a little complicated as a Java class can only extend one other class and some code might end up being duplicated across a number of classes. I wanted to know what are the best practices for modeling such relationships neatly and concisely using Hibernate?

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  • How can I work around the fact that in C++, sin(M_PI) is not 0?

    - by Adam Doyle
    In C++, const double Pi = 3.14159265; cout << sin(Pi); // displays: 3.58979e-009 it SHOULD display the number zero I understand this is because Pi is being approximated, but is there any way I can have a value of Pi hardcoded into my program that will return 0 for sin(Pi)? (a different constant maybe?) In case you're wondering what I'm trying to do: I'm converting polar to rectangular, and while there are some printf() tricks I can do to print it as "0.00", it still doesn't consistently return decent values (in some cases I get "-0.00") The lines that require sin and cosine are: x = r*sin(theta); y = r*cos(theta); BTW: My Rectangular - Polar is working fine... it's just the Polar - Rectangular Thanks! edit: I'm looking for a workaround so that I can print sin(some multiple of Pi) as a nice round number to the console (ideally without a thousand if-statements) edit: In case anyone's curious, this was what I landed on: double sin2(double theta) // in degrees { double s = sin(toRadians(theta)); if (fabs(s - (int)s) < 0.000001) { return floor(s + 0.5); } return s; } where toRadians() is a macro that converts to radians

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  • Mouse move panning

    - by Rudy
    Hi all, I'm trying to scroll a series of thumbnails horizontally based on the mouseX position. I can get it to scroll but it's very choppy and for some reason it's not reading my start and end numbers so it will stop scrolling. Can anyone point me in the right direction? Thanks. var thumbBounds:Object = new Object(); thumbBounds = thumbContainer.getBounds(this); thumbContainer.addEventListener(MouseEvent.MOUSE_OVER, setScrolling); private function setScrolling(me:MouseEvent):void { thumbContainer.removeEventListener(MouseEvent.MOUSE_OVER, setScrolling); stage.addEventListener(Event.ENTER_FRAME, scrollThumbs); } private function scrollThumbs(e:Event):void { if(mouseX <= thumbBounds.x || mouseX thumbBounds.width || mouseX < thumbBounds.y || mouseX thumbBounds.height) { thumbContainer.addEventListener(MouseEvent.MOUSE_OVER, setScrolling); stage.removeEventListener(Event.ENTER_FRAME, scrollThumbs); } if(thumbContainer.x = 0) { thumbContainer.x = 0; } if(thumbContainer.x <= -842) { thumbContainer.x = -842; } var xdist:Number = new Number(); xdist = mouseX - 382; thumbContainer.x += Math.round(-xdist / 10); }

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