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• What's the best way to store Logon User information for Web Application?

  - by Morgan Cheng

  I was once in a project of web application developed on ASP.NET. For each logon user, there is an object (let's call it UserSessionObject here) created and stored in RAM. For each HTTP request of given user, matching UserSessoinObject instance is used to visit user state information and connection to database. So, this UserSessionObject is pretty important. This design brings several problems found later: 1) Since this UserSessionObject is cached in ASP.NET memory space, we have to config load balancer to be sticky connection. That is, HTTP request in single session would always be sent to one web server behind. This limit scalability and maintainability. 2) This UserSessionObject is accessed in every HTTP request. To keep the consistency, there is a exclusive lock for the UserSessionObject. Only one HTTP request can be processed at any given time because it must to obtain the lock first. The performance and response time is affected. Now, I'm wondering whether there is better design to handle such logon user case. It seems Sharing-Nothing-Architecture helps. That means long user info is retrieved from database each time. I'm afraid that would hurt performance. Is there any design pattern for long user web app? Thanks.

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• How to refresh/redraw the screen (not the program window)

  - by mohrphium

  I'm having a bit of a hard time figuring out, how to remove a drawn ellipse after it has been drawn somewhere else. I need a circle to follow my mouse all the time and this is all the program should do. I get the mousepositions and draw my circle but how can I remove the last one? #include <Windows.h> #include <iostream> void drawRect(int a1, int a2){ HDC screenDC = ::GetDC(0); //Draw circle at mouse position ::Ellipse(screenDC, a1, a2+5, a1+9, a2+14); ::ReleaseDC(0, screenDC); //::InvalidateRect(0, NULL, TRUE); //<- I tried that but then everything flickers //Also, the refresh rate is not fast enough... still some circles left } int main(void) { int a1; int a2; bool exit=false; while (exit!=true) { POINT cursorPos; GetCursorPos(&cursorPos); float x = 0; x = cursorPos.x; float y = 0; y = cursorPos.y; a1=(int)cursorPos.x; a2=(int)cursorPos.y; drawRect(a1, a2); } } I am working with graphics and all that stuff for the first time. Im kinda stuck here... once again. Thanks.

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• Draw a comparison between an integer in a specific row and a count

  - by XCoderX

  This is a follow-up question to this one: Check for specific integer in a row WHERE user = $name I want a user to be able to comment on my site for exactly five times a day. After this five times, the user has to wait 24 hours. In order to accomplish that I raise a counter in my MYSQL database, right next to the user. So where the name of the user is, there is where the counter gets raised. When it reaches 5 it should stop counting and reset after 24 hours. In order to check the time I use a timestamp. I check if the timestamp is older than 24 hours. If that is the case, the counter gets reseted (-5) and the user can comment again. In order to do that, I use the following code, however it never stops at five, my guess is that my comparison is wrong somehow: $counter = "SELECT FROM table VALUES CommentCounterReset WHERE Name = '$name'"; if(!isset($_SESSION['ts'])); { $_SESSION['ts'] = time(); } if ($counter >= 5) { if (time() - $_SESSION['ts'] <= 60*60*24){ echo "You already wrote five comments."; } else { $sql = "UPDATE table SET CommentCounterReset = CommentCounterReset-5 WHERE Name = '$name'"; } } else { $sql = "UPDATE table SET CommentCounterReset = CommentCounterReset+1 WHERE Name = '$name'"; echo "Your comment has been added."; }

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• php paging and the use of limit clause

  - by Average Joe

  Imagine you got a 1m record table and you want to limit the search results down to say 10,000 and not more than that. So what do I use for that? Well, the answer is use the limit clause. example select recid from mytable order by recid asc limit 10000 This is going to give me the last 10,000 records entered into this table. So far no paging. But the limit phrase is already in use. That brings to question to the next level. What if I want to page thru this record particular record set 100 recs at a time? Since the limit phrase is already part of the original query, how do I use it again, this time to take care of the paging? If the org. query did not have a limit clause to begin with, I'd adjust it as limit 0,100 and then adjusting it as 100,100 and then 200,100 and so on while the paging takes it course. But at this time, I cannot. You almost think you'd want to use two limit phrases one after the other - which is not not gonna work. limit 10000 limit 0,1000 for sure it would error out. So what's the solution in this particular case?

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• Firefox extension js object initialization

  - by Michael

  Note: this is about Firefox extension, not a js general question. In Firefox extension project I need my javascript object to be initialized just once per Firefox window. Otherwise each time I open my window a new timers will be engaged, new properties will be used, so everything will start from scratch. hope example below will demystify my question :) var StupidExtension { statusBarValue: "Not Initialized Yet", startup: function () { ... // Show statusBarValue in Status Bar Panel }, initTimerToRetrieveStatusBarValueFromNetwork: function () { ... } } so each time you hit Ctrl+N a new window you will see "Not Initialized Yet" and then new timer will be fired, so after some time it retrieve data from network you will see value also on second window and so on. Ideally would be to have just a single timer function running and updating all status bar panels in all Firefox windows. Of course I can do some caching, like saving the value in prefs or some other storage, then show it from there. But I feel like this is artificial. So the question will be is there "native" technique of making static some parts of the object among all Firefox window instances?

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• Is there really such a thing as "being good at math"?

  - by thezhaba

  Aside from gifted individuals able to perform complex calculations in their head, I'm wondering if proficiency in mathematics, namely calculus and algebra, has really got to do with one's natural inclination towards sciences, if you can put it that way. A number of students in my calculus course pick up material in seemingly no time whereas I, personally, have to spend time thinking about and understanding most concepts. Even then, if a question that requires a bit more 'imagination' comes up I don't always recognize the concepts behind it, as is the case with calculus proofs, for instance. Nevertheless, I refuse to believe that I'm simply not made for it. I do very well in programming and software engineering courses where a lot of students struggle. At first I could not grasp what they found to be so difficult, but eventually I realized that having previous programming experience is a great asset -- once I've seen and made practical use of the programming concepts learning about them in depth in an academic setting became much easier as I have then already seen their use "in the wild". I suppose I'm hoping that something similar happens with mathematics -- perhaps once the practical idea behind a concept (which authors of textbooks sure do a great job of concealing..) is evident, understanding the seemingly dry and symbolic ideas and proofs would be more obvious? I'm really not sure. All I'm sure of is I'd like to get better at calculus, but I don't yet understand why some of us pick it up easily while others have to spend considerable amounts of time on it and still not have complete understanding if an unusual problem is given.

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• XSLT 1.0: restrict entries in a nodeset

  - by Mike

  Hi, Being relatively new to XSLT I have what I hope is a simple question. I have some flat XML files, which can be pretty big (eg. 7MB) that I need to make 'more hierarchical'. For example, the flat XML might look like this: <D0011> .... .... and it should end up looking like this: <D0011> .... .... I have a working XSLT for this, and it essentially gets a nodeset of all the b elements and then uses the 'following-sibling' axis to get a nodeset of the nodes following the current b node (ie. following-sibling::*[position() =$nodePos]). Then recursion is used to add the siblings into the result tree until another b element is found (I have parameterised it of course, to make it more generic). I also have a solution that just sends the position in the XML of the next b node and selects the nodes after that one after the other (using recursion) via a *[position() = $nodePos] selection. The problem is that the time to execute the transformation increases unacceptably with the size of the XML file. Looking into it with XML Spy it seems that it is the 'following-sibling' and 'position()=' that take the time in the two respective methods. What I really need is a way of restricting the number of nodes in the above selections, so fewer comparisons are performed: every time the position is tested, every node in the nodeset is tested to see if its position is the right one. Is there a way to do that ? Any other suggestions ? Thanks, Mike

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• MAAttachedWindow hide

  - by Montecorte

  I had the same problem that The-Kenny at this post but I fixed it adding the windowDidResignKey: method on the MAAttachedWindow.m, but now my problem is that when I click outside the StatusBar item keeps blue background and when I click another time on the status item it goes normally and I have to click a second time on it to show the window. I tried to add a method in the CustomView (the view of the status item) that do the same thing that te mouseDown method: - (void)mouseDown:(NSEvent *)event { NSRect frame = [[self window] frame]; NSPoint pt = NSMakePoint(NSMidX(frame), NSMidY(frame)); NSLog(@"%g,%g",pt.x,pt.y); clicked = !clicked; [controller toggleAttachedWindowAtPoint:pt]; [self setNeedsDisplay:YES];} my method is: - (void)windowDidResignKey { NSLog(@"Resigned"); NSRect frame = [[self window] frame]; NSPoint pt = NSMakePoint(NSMidX(frame), NSMidY(frame)); NSLog(@"%g,%g",pt.x,pt.y); clicked = !clicked; [controller toggleAttachedWindowAtPoint:pt]; [self setNeedsDisplay:YES];} I call this method in the windowDidResignKey that I have defined on MAAttachedWindow.m, but this method dont call correctly the toggleAttachedWindowAtPoint method, I dont know exactly why, it's only called when I click another time over the status item If anybody knows how to do that any help would be fine. Thank you so much :)

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• Communication between lexer and parser

  - by FredOverflow

  Every time I write a simple lexer and parser, I stumble upon the same question: how should the lexer and the parser communicate? I see four different approaches: The lexer eagerly converts the entire input string into a vector of tokens. Once this is done, the vector is fed to the parser which converts it into a tree. This is by far the simplest solution to implement, but since all tokens are stored in memory, it wastes a lot of space. Each time the lexer finds a token, it invokes a function on the parser, passing the current token. In my experience, this only works if the parser can naturally be implemented as a state machine like LALR parsers. By contrast, I don't think it would work at all for recursive descent parsers. Each time the parser needs a token, it asks the lexer for the next one. This is very easy to implement in C# due to the yield keyword, but quite hard in C++ which doesn't have it. The lexer and parser communicate through an asynchronous queue. This is commonly known under the title "producer/consumer", and it should simplify the communication between the lexer and the parser a lot. Does it also outperform the other solutions on multicores? Or is lexing too trivial? Is my analysis sound? Are there other approaches I haven't thought of? What is used in real-world compilers? It would be really cool if compiler writers like Eric Lippert could shed some light on this issue.

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• How are developers using source control, I am trying to find the most efficient way to do source con

  - by RJ

  I work in a group of 4 .Net developers. We rarely work on the same project at the same time but it does happen from time to time.We use TFS for source control. My most recent example is a project I just placed into production last night that included 2 WCF services and a web application front end. I worked out of a branch called "prod" because the application is brand new and has never seen the light of day. Now that the project is live, I need to branch off the prod branch for features, bugs, etc... So what is the best way to do this? Do I simple create a new branch and sort of archive the old branch and never use it again? Do I branch off and then merge my branch changes back into the prod branch when I want to deploy to production? And what about the file and assembly version. They are currently at 1.0.0.0. When do they change and why? If I fix a small bug, which number changes if any? If I add a feature, which number changes if any? What I am looking for is what you have found to be the best way to efficiently manage source control. Most places I have worked always seem to bang heads with the source control system in on way or another and I would just like to find out what you have found that works the best.

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• [C#] how to do Exception Handling & Tracing

  - by shrimpy

  Hi all, i am reading some C# books, and got some exercise don't know how to do, or not sure what does the question mean. Problem: After working for a company for some time, your skills as a knowledgeable developer are recognized, and you are given the task of “policing” the implementation of exception handling and tracing in the source code (C#) for an enterprise application that is under constant incremental development. The two goals set by the product architect are: 100% of methods in the entire application must have at least a standard exception handler, using try/catch/finally blocks; more complex methods must also have additional exception handling for specific exceptions All control flow code can optionally write “tracing” information to assist in debugging and instrumentation of the application at run-time in situations where traditional debuggers are not available (eg. on staging and production servers). (i am not quite understand these criterias, i came from the java world, java has two kind of exception, check and unchecked exception. Developer must handle checked exception, and do logging. about unchecked exception, still do logging maybe, but most of the time we just throw it. however here comes to C#, what should i do????) Question for Problem: List rules you would create for the development team to follow, and the ways in which you would enforce rules, to achieve these goals. How would you go about ensuring that all existing code complies with the rules specified by the product architect; in particular, what considerations would impact your planning for the work to ensure all existing code complies?

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• use of ajax in django problem with the code

  - by tazim

  I am new to ajax and using Django for web development. Now My Template contains : sample.html <html> <body> <script language="javascript" type="text/javascript"> //Browser Support Code function ajaxFunction(){ var ajaxRequest; // The variable that makes Ajax possible! try{ // Opera 8.0+, Firefox, Safari ajaxRequest = new XMLHttpRequest(); } catch (e){ // Internet Explorer Browsers try{ ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) { try{ ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP"); } catch (e){ // Something went wrong alert("Your browser broke!"); return false; } } } // Create a function that will receive data sent from the server ajaxRequest.onreadystatechange = function(){ if(ajaxRequest.readyState == 4){ document.myForm.time.value = ajaxRequest.responseText; } } ajaxRequest.open("GET", "/showtime/", true); ajaxRequest.send(null); } </script> <form name='myForm'> Name: <input type='text' onBlur="ajaxFunction();" name='username' /> <br /> Time: <input type='text' name='time' /> </form> </body> </html> In views.py my function is : def showtime(request): string = "Ajax Application" data = {"string" : string} pprint (data) return render_to_response("sample.html",data) Now, The output is not as expected . The template does not receives the response sent by the server What is wrong with the code ?

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• MySQL 5.5.8 Gets Periodic Lag

  - by CYREX

  Am using MySQL 5.5.8 on an Ubuntu system and every X amount of time it creates a huge lag that lasts a couple of seconds. Then all goes back to normal until the next lag. The time period varies but it looks like it happen periodically. Am using InnoDB. It is like hiccups in the MySQL. What could be creating this sort of periodic problem. Do not have any cron jobs or process running every time the X period happens. The X period could be between 30 minutes to 2 hours. So for example it could happen every 30 minutes for the next 12 hours or it could happen every 2 hours for the next 8 hours. key_buffer_size = 256M max_allowed_packet = 1M table_cache = 1024 table_open_cache = 1024 sort_buffer_size = 2M read_buffer_size = 2M read_rnd_buffer_size = 4M myisam_sort_buffer_size = 32M thread_cache_size = 128 query_cache_size= 128M log-slow-queries = slow.log long_query_time = 5 log-queries-not-using-indexes # Try number of CPU's*2 for thread_concurrency thread_concurrency = 4 max_connections=512 #innodb_data_file_path = ibdata1:10M:autoextend #innodb_log_group_home_dir = /usr/local/mysql/data # You can set .._buffer_pool_size up to 50 - 80 % # of RAM but beware of setting memory usage too high innodb_buffer_pool_size = 1G #innodb_additional_mem_pool_size = 20M # Set .._log_file_size to 25 % of buffer pool size #innodb_log_file_size = 64M #innodb_log_buffer_size = 8M #innodb_flush_log_at_trx_commit = 0 #innodb_lock_wait_timeout = 50 [mysqldump] quick max_allowed_packet = 16M [myisamchk] key_buffer_size = 64M sort_buffer_size = 64M read_buffer = 2M write_buffer = 2M There are about 200+ tables divided in 3 databases. The most written too is in InnoDB. The other ones are more read. Several of the tables in the InnoDB have more than 2 million records. The other databases top at about 400 thousand records and do not change so often. The PC is a Core 2 Duo 8400 with 4GB RAM, 32Bit Ubuntu.

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• different thread accessing MemoryStream

  - by Wayne

  There's a bit of code which writes data to a MemoryStream object directly into it's data buffer by calling GetBuffer(). It also uses and updates the Position and SetLength() properties appropriately. This code works purposes 99.9999% of the time. Literally. Only every so many 100,000's of iterations it will barf. The specific problem is that the memory.Position property suddenly returns zero instead of the appropriate value. However, code was added that checks for the 0 and throws an exception which include log of the MemoryStream properties like Position and Length in a separate method. Those return the correct value. Further addition shows that when this rare condition occurs, the memory.Position only has zero inside this particular method. Okay. Obviously, this must be a threading issue. But this code is well locked. However, the nature of this software is that it's organized by "tasks" with a scheduler and so any one of several actual O/S thread may run this code at any give time--but never more than one at a time. So it's my guess that ordinarily it so happens that the same thread keeps getting used for this method and then on a rare occasion a different thread get used. Then due to compiler optimizations, the different thread never gets the correct value. It gets a "stale" value. Ordinarily in a situation like this I would apply a "volatile" keyword to the variable in question. But that (those) variables are inside the MemoryStream object. Does anyone have any other idea? Or does this mean we have to implement our own MemoryStream object? (Just like we end up having to do with practically every collection in .NET?) It's a shame to have such an awesome platform as .NET and have virtually the entire system useless as-is for seriously parallelized applications. If I'm wrong or you have other ideas, please advise. Sincerely, Wayne

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• FFT and IFFT on 3D matrix (Matlab)

  - by SteffenDM

  I have a movie with 70 grayscale frames in MATLAB. I have put them in a 3-D matrix, so the dimensions are X, Y and time. I want to determine the frequencies in the time dimension, so I have to calculate the FFT for every point in the 3rd dimension. This is not a problem but I have to return the images to the original form with ifft. In a normal situation this would be true: X = ifft(fft(X)), but this is not the case it seems in MATLAB when you work with multidimensional data. This is the code I use: for i = 1:length y(:, :, i) = [img1{i, level}]; %# take each picture from an cell array and put it end %# and put it in 3D array y2 = ifft(fft(y, NFFT,3), NFFT, 3); %# NFFT = 128, the 3 is the dimension in which i want %# to calculate the FFT and IFFT y is 480x640x70, so there are 70 images of 640x480 pixels. If I use only fft, y2 is 480x640x128 (this is normal because we want 128 points with NFFT). If I use fft and ifft, y2 is 480x640x128 pixels. This is not normal, the 128 should be 70 again. I tried to do it in just one dimension by using 2 for loops and this works fine. The for loops take to much time, though.

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• Checking if an SSH tunnel is up and running

  - by Jarmund

  I have a perl script which, when destilled a bit, looks like this: my $randport = int(10000 + rand(1000)); # Random port as other scripts like this run at the same time my $localip = '192.168.100.' . ($port - 4000); # Don't ask... backwards compatibility system("ssh -NL $randport:$localip:23 root\@$ip -o ConnectTimeout=60 -i somekey &"); # create the tunnel in the background sleep 10; # Give the tunnel some time to come up # Create the telnet object my $telnet = new Net::Telnet( Timeout => 10, Host => 'localhost', Port => $randport, Telnetmode => 0, Errmode => \&fail, ); # SNIPPED... a bunch of parsing data from $telnet The thing is that the target $ip is on a link with very unpredictable bandwidth, so the tunnel might come up right away, it might take a while, it might not come up at all. So a sleep is necessary to give the tunnel some time to get up and running. So the question is: How can i test if the tunnel is up and running? 10 seconds is a really undesirable delay if the tunnel comes up straight away. Ideally, i would like to check if it's up and continue with creating the telnet object once it is, to a maximum of, say, 30 seconds.

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• Improve Efficiency in Array comparison in Ruby

  - by user2985025

  Hi I am working on Ruby /cucumber and have an requirement to develop a comparison module/program to compare two files. Below are the requirements The project is a migration project . Data from one application is moved to another Need to compare the data from the existing application against the new ones. Solution : I have developed a comparison engine in Ruby for the above requirement. a) Get the data, de duplicated and sorted from both the DB's b) Put the data in a text file with "||" as delimiter c) Use the key columns (number) that provides a unique record in the db to compare the two files For ex File1 has 1,2,3,4,5,6 and file2 has 1,2,3,4,5,7 and the columns 1,2,3,4,5 are key columns. I use these key columns and compare 6 and 7 which results in a fail. Issue : The major issue we are facing here is if the mismatches are more than 70% for 100,000 records or more the comparison time is large. If the mismatches are less than 40% then comparison time is ok. Diff and Diff -LCS will not work in this case because we need key columns to arrive at accurate data comparison between two applications. Is there any other method to efficiently reduce the time if the mismatches are more thatn 70% for 100,000 records or more. Thanks

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• Basic problems (type inference or something else?) in Objective-C/Cocoa.

  - by Matt

  Hi, Apologies for how basic these questions are to some. Just started learning Cocoa, working through Hillegass' book, and am trying to write my first program (a GUI Cocoa app that counts the number of characters in a string). I tried this: NSString *string = [textField stringValue]; NSUInteger *stringLength = [string length]; NSString *countString = (@"There are %u characters",stringLength); [label setStringValue:countString]; But I'm getting errors like: Incompatible pointer conversion initializing 'NSUInteger' (aka 'unsigned long'), expected 'NSUInteger *'[-pedantic] for the first line, and this for the second line: Incompatible pointer types initializing 'NSUInteger *', expected 'NSString *' [-pedantic] I did try this first, but it didn't work either: [label setStringValue:[NSString stringWithFormat:@"There are %u characters",[[textField stringValue] length]]] On a similar note, I've only written in easy scripting languages before now, and I'm not sure when I should be allocing/initing objects and when I shouldn't. For example, when is it okay to do this: NSString *myString = @"foo"; or int *length = 5; instead of this: NSString *myString = [[NSString alloc] initWithString:"foo"]; And which ones should I be putting into the header files? I did check Apple's documentation, and CocoaDev, and the book I'm working for but without luck. Maybe I'm looking in the wrong places.. Thanks to anyone who takes the time to reply this: it's appreciated, and thanks for being patient with a beginner. We all start somewhere. EDIT Okay, I tried the following again: [label setStringValue:[NSString stringWithFormat:@"There are %u characters",[[textField stringValue] length]]] And it actually worked this time. Not sure why it didn't the first time, though I think I might have typed %d instead of %u by mistake. However I still don't understand why the code I posted at the top of my original post doesn't work, and I have no idea what the errors mean, and I'd very much like to know because it seems like I'm missing something important there.

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• Java reflection appropriateness

  - by jsn

  This may be a fairly subjective question, but maybe not. My application contains a bunch of forms that are displayed to the user at different times. Each form is a class of its own. Typically the user clicks a button, which launches a new form. I have a convenience function that builds these buttons, you call it like this: buildButton( "button text", new SelectionAdapter() { @Override public void widgetSelected( SelectionEvent e ) { showForm( new TasksForm( args... ) ); } } ); I do this dozens of times, and it's really cumbersome having to make a SelectionAdapter every time. Really all I need for the button to know is what class to instantiate when it's clicked and what arguments to give the constructor, so I built a function that I call like this instead: buildButton( "button text", TasksForm.class, args... ); Where args is an arbitrary list of objects that you could use to instantiate TasksForm normally. It uses reflection to get a constructor from the class, match the argument list, and build an instance when it needs to. Most of the time I don't have to pass any arguments to the constructor at all. The downside is obviously that if I'm passing a bad set of arguments, it can't detect that at compilation time, so if it fails, a dialog is displayed at runtime. But it won't normally fail, and it'll be easy to debug if it does. I think this is much cleaner because I come from languages where the use of function and class literals is pretty common. But if you're a normal Java programmer, would seeing this freak you out, or would you appreciate not having to scan a zillion SelectionAdapters?

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• C# Type conversion between two similar Datatable objects

  - by Ali

  I have .NET project with sync framework and two separate Datasets for MS SQL and Compact SQL. in my base class I have a generic DataTable object. in my derived classed I assign Typed DataTable to the generic object based on whether the application is operating online or offline: example: if (online) _dataTable = new MSSQLDataSet.Customer; else _dataTable = new CompactSQLDataSet.Customer; Now every where in my code i have to check and do a cast based on the current network mode like this: public void changeCustomerID(int ID) { if (online) (MSSQLDataSet.CustomerDataTable)_dataTable)[i].CustomerID = value; else (CompactMSSQLDataSet.CustomerDataTable)_dataTable)[i].CustomerID = value; } but I don't think this is very efficient and I believe it can be done in a smarter way to only use one line of code by dynamically getting the Type of _dataTable on the run time. my problem is at the design time, in order to acess datatable porperties such as "CustomerID" it has to be casted to either MSSQLDataSet.CustomerDataTable or CompactMSSQLDataSet.CustomerDataTable. Is there a way to have a function or a operator to convert the _datatable to its runtime type but still be able to use it's design time properties which are the same between the two types? something like: ((aType)_dataTable)[i].CustomerID = value; //or GetRuntimeType(_dataTable)[i].CustomerID = value;

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• Classical task-scheduling assignment

  - by Bruno

  I am working on a flight scheduling app (disclaimer: it's for a college project, so no code answers, please). Please read this question w/ a quantum of attention before answering as it has a lot of peculiarities :( First, some terminology issues: You have planes and flights, and you have to pair them up. For simplicity's sake, we'll assume that a plane is free as soon as the flight using it prior lands. Flights are seen as tasks: They have a duration They have dependencies They have an expected date/time for beginning Planes can be seen as resources to be used by tasks (or flights, in our terminology). Flights have a specific type of plane needed. e.g. flight 200 needs a plane of type B. Planes obviously are of one and only one specific type, e.g., Plane Airforce One is of type C. A "project" is the set of all the flights by an airline in a given time period. The functionality required is: Finding the shortest possible duration for a said project The earliest and latest possible start for a task (flight) The critical tasks, with basis on provided data, complete with identifiers of preceding tasks. Automatically pair up flights and planes, so as to get all flights paired up with a plane. (Note: the duration of flights is fixed) Get a Gantt diagram with the projects scheduling, in which all flights begin as early as possible, showing all previously referred data graphically (dependencies, time info, etc.) So the questions is: How in the world do I achieve this? Particularly: We are required to use a graph. What do the graph's edges and nodes respectively symbolise? Are we required to discard tasks to achieve the critical tasks set? If you could also recommend some algorithms for us to look up, that'd be great.

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• Getting an updated location in Android

  - by jul

  Hi, I'm using the code shown below to get an updated value for location every time a button is clicked. When my activity is resumed I get an update every second, so that when I call getLastKnownLocation I expect to have a location that have been updated in the last second. Is that the correct way to do that? I would expect the onLocationChanged event to be triggered every time I execute a 'geo fix' command (or max after 1s since I request update every 1s), but it's only triggered the first time. Why? Any help/suggestion welcome! Thanks package org.digitalfarm.atable; ... public class Atable extends Activity { private Button mSearchButton; private TextView mytext; private LocationManager locationManager; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mSearchButton = (Button)this.findViewById(R.id.button); mytext = (TextView) findViewById(R.id.dude); locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE); final Criteria criteria = new Criteria(); criteria.setAccuracy(Criteria.ACCURACY_FINE); mSearchButton.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { String provider = locationManager.getBestProvider(criteria, true); Location location = locationManager.getLastKnownLocation(provider); } }); } //Start a location listener LocationListener onLocationChange=new LocationListener() { public void onLocationChanged(Location loc) { //sets and displays the lat/long when a location is provided String latlong = "Lat: " + loc.getLatitude() + " Long: " + loc.getLongitude(); mytext.setText(latlong); } public void onProviderDisabled(String provider) { // required for interface, not used } public void onProviderEnabled(String provider) { // required for interface, not used } public void onStatusChanged(String provider, int status, Bundle extras) { // required for interface, not used } }; //pauses listener while app is inactive @Override public void onPause() { super.onPause(); locationManager.removeUpdates(onLocationChange); } //reactivates listener when app is resumed @Override public void onResume() { super.onResume(); locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,1000,100.0f,onLocationChange); } }

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• SQL Server job (stored proc) trace

  - by Jit

  Hi Friends, I need your suggestion on tracing the issue. We are running data load jobs at early morning and loading the data from Excel file into SQL Server 2005 db. When job runs on production server, many times it takes 2 to 3 hours to complete the tasks. We could drill down to one job step which is taking 99% of the total time to finish. While running the job step (stored procs) on staging environment (with the same production database restored) takes 9 to 10 minutes, the same takes hours on production server when it run at early morning as part of job. The production server always stuck up at the very job step. I would like to run trace on the very job step (around 10 stored procs run for each user in while loop within the job step) and collect the info to figure out the issue. What are the ways available in SQL Server 2005 to achieve the same? I want to run the trace only for these SPs and not for certain period time period on production server, as trace give lots of information and it becomes very difficult for me (as not being DBA) to analyze that much of trace information and figure out the issue. So I want to collect info about specific SPs only. Let me know what you suggest. Appreciate your time and help. Thanks.

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• Determining if an unordered vector<T> has all unique elements

  - by Hooked

  Profiling my cpu-bound code has suggested I that spend a long time checking to see if a container contains completely unique elements. Assuming that I have some large container of unsorted elements (with < and = defined), I have two ideas on how this might be done: The first using a set: template <class T> bool is_unique(vector<T> X) { set<T> Y(X.begin(), X.end()); return X.size() == Y.size(); } The second looping over the elements: template <class T> bool is_unique2(vector<T> X) { typename vector<T>::iterator i,j; for(i=X.begin();i!=X.end();++i) { for(j=i+1;j!=X.end();++j) { if(*i == *j) return 0; } } return 1; } I've tested them the best I can, and from what I can gather from reading the documentation about STL, the answer is (as usual), it depends. I think that in the first case, if all the elements are unique it is very quick, but if there is a large degeneracy the operation seems to take O(N^2) time. For the nested iterator approach the opposite seems to be true, it is lighting fast if X[0]==X[1] but takes (understandably) O(N^2) time if all the elements are unique. Is there a better way to do this, perhaps a STL algorithm built for this very purpose? If not, are there any suggestions eek out a bit more efficiency?

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• Type of member is not CLS-compliant

  - by John Galt

  Using Visual Studio 2008 and VB.Net: I have a working web app that uses an ASMX web service which is compiled into its separate assembly. I have another class library project compiled as a separate assembly that serves as a proxy to this web service. This all seems to work at runtime but I am getting this warning at compile time which I don't understand and would like to fix: Type of member 'wsZipeee' is not CLS-compliant I have dozens of webforms in the main project that reference the proxy class with no compile time complaints as this snippet shows: Imports System.Data Partial Class frmZipeee Inherits System.Web.UI.Page Public wsZipeee As New ProxyZipeeeService.WSZipeee.Zipeee Dim dsStandardMsg As DataSet Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load And yet I have one webform (also in the root of the main project) which gives me the "not CLS-compliant" message but yet attempts to reference the proxy class just like the other ASPX files. I get the compile time warning on the line annoted by me with 'ERROR here.. Imports System.Data Partial Class frmHome Inherits System.Web.UI.Page Public wsZipeee As New ProxyZipeeeService.WSZipeee.Zipeee ERROR here Dim dsStandardMsg As DataSet Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load This makes no sense to me. The file with the warning is called frmHome.aspx.vb; all others in the project declare things the same way and have no warning. BTW, the webservice itself returns standard datatypes: integer, string, and dataset.

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