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  • How do I create a Spring 3 + Tiles 2 webapp using REST-ful URLs?

    - by Ichiro Furusato
    I'm having a heck of a time resolving URLs with Spring 3.0 MVC. I'm just building a HelloWorld to try out how to build a RESTful webapp in Spring, nothing theoretically complicated. All of the examples I've been able to find are based on configurations that pay attention to file extensions ("*.htm" or "*.do"), include an artificial directory name prefix ("/foo") or even prefix paths with a dot (ugly), all approaches that use some artificial regex pattern as a signal to the resolver. For a REST approach I want to avoid all that muck and use only the natural URL patterns of my application. I would assume (perhaps incorrectly) that in web.xml I'd set a url-pattern of "/*" and pass everything to the DispatcherServlet for resolution, then just rely on URL patterns in my controller. I can't reliably get my resolver(s) to catch the URL patterns, and in all my trials this results in a resource not found error, a stack overflow (loop), or some kind of opaque Spring 3 ServletException stack trace — one of my ongoing frustrations with Spring generally is that the error messages are not often very helpful. I want to work with a Tiles 2 resolver. I've located my *.jsp files in WEB-INF/views/ and have a single line index.jsp file at the application root redirecting to the index file set by my layout.xml (the Tiles 2 Configurer). I do all the normal Spring 3 high-level configuration: <mvc:annotation-driven /> <mvc:view-controller path="/" view-name="index"/> <context:component-scan base-package="com.acme.web.controller" /> ...followed by all sorts of combinations and configurations of UrlBasedViewResolver, InternalResourceViewResolver, UrlFilenameViewController, etc. with all manner of variantions in my Tiles 2 configuration file. Then in my controller I've trying to pick up my URL patterns. Problem is, I can't reliably even get the resolver(s) to catch the patterns to send to my controller. This has now stretched to multiple days with no real progress on something I thought would be very simple to implement. I'm perhaps trying to do too much at once, though I would think this should be a simple (almost a default) configuration. I'm just trying to create a simple HelloWorld-type application, I wouldn't expect this is rocket science. Rather than me post my own configurations (which have ranged all over the map), does anyone know of an online example that: shows a simple Spring 3 MVC + Tiles 2 web application that uses REST-ful URLs (i.e., avoiding forced URL patterns such as file extensions, added directory names or dots) and relies solely on Spring 3 code/annotations (i.e., nothing outside of Spring MVC itself) to accomplish this? Is there an easy way to do this? Thanks very much for any help.

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  • What is a good platform for building a game framework targetting both web and native languages?

    - by fuzzyTew
    I would like to develop (or find, if one is already in development) a framework with support for accelerated graphics and sound built on a system flexible enough to compile to the following: native ppc/x86/x86_64/arm binaries or a language which compiles to them javascript actionscript bytecode or a language which compiles to it (actionscript 3, haxe) optionally java I imagine, for example, creating an API where I can open windows and make OpenGL-like calls and the framework maps this in a relatively efficient manner to either WebGL with a canvas object, 3d graphics in Flash, OpenGL ES 2 with EGL, or desktop OpenGL in an X11, Windows, or Cocoa window. I have so far looked into these avenues: Building the game library in haXe Pros: Targets exist for php, javascript, actionscript bytecode, c++ High level, object oriented language Cons: No support for finally{} blocks or destructors, making resource cleanup difficult C++ target does not allow room for producing highly optimized libraries -- the foreign function interface requires all primitive types be boxed in a wrapper object, as if writing bindings for a scripting language; these feel unideal for real-time graphics and audio, especially exporting low-level functions. Doesn't seem quite yet mature Using the C preprocessor to create a translator, writing programs entirely with macros Pros: CPP is widespread and simple to use Cons: This is an arduous task and probably the wrong tool for the job CPP implementations differ widely in support for features (e.g. xcode cpp has no variadic macros despite claiming C99 compliance) There is little-to-no room for optimization in this route Using llvm's support for multiple backends to target c/c++ to web languages Pros: Can code in c/c++ LLVM is a very mature highly optimizing compiler performing e.g. global inlining Targets exist for actionscript (alchemy) and javascript (emscripten) Cons: Actionscript target is closed source, unmaintained, and buggy. Javascript targets do not use features of HTML5 for appropriate optimization (e.g. linear memory with typed arrays) and are immature An LLVM target must convert from low-level bytecode, so high-level constructs are lost and bloated unreadable code is created from translating individual instructions, which may be more difficult for an unprepared JIT to optimize. "jump" instructions cause problems for languages with no "goto" statements. Using libclang to write a translator from C/C++ to web languages Pros: A beautiful parsing library providing easy access to the code structure Can code in C/C++ Has sponsored developer effort from Apple Cons: Incomplete; current feature set targets IDEs. Basic operators are unexposed and must be manually parsed from the returned AST element to be identified. Translating code prior to compilation may forgo optimizations assumed in c/c++ such as inlining. Creating new code generators for clang to translate into web languages Pros: Can code in C/C++ as libclang Cons: There is no API; code structure is unstable A much larger job than using libclang; the innards of clang are complex Building the game library in Common Lisp Pros: Flexible, ancient, well-developed language Extensive introspection should ease writing translators Translators exist for at least javascript Cons: Unfamiliar language No standardized library functions, widely varying implementations Which of these avenues should I pursue? Do you know of any others, or any systems that might be useful? Does a general project like this exist somewhere already? Thank you for any input.

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  • dynamiclly schedule a lead sales agent

    - by Josh
    I have a website that I'm trying to migrate from classic asp to asp.net. It had a lead schedule, where each sales agent would be featured for the current day, or part of the day.The next day a new agent would be scheduled. It was driven off a database table that had a row for each day in it. So to figure out if a sales agent would show on a day, it was easy, just find today's date in the table. Problem was it ran out rows, and you had to run a script to update the lead days 6 months at a time. Plus if there was ever any change to the schedule, you had to delete all the rows and re-run the script. So I'm trying to code it where sql server figures that out for me, and no script has to be ran. I have a table like so CREATE TABLE [dbo].[LeadSchedule]( [leadid] [int] IDENTITY(1,1) NOT NULL, [userid] [int] NOT NULL, [sunday] [bit] NOT NULL, [monday] [bit] NOT NULL, [tuesday] [bit] NOT NULL, [wednesday] [bit] NOT NULL, [thursday] [bit] NOT NULL, [friday] [bit] NOT NULL, [saturday] [bit] NOT NULL, [StartDate] [smalldatetime] NULL, [EndDate] [smalldatetime] NULL, [StartTime] [time](0) NULL, [EndTime] [time](0) NULL, [order] [int] NULL, So the user can schedule a sales agent depending on their work schedule. Also if they wanted to they could split certain days, or sales agents by time, So from Midnight to 4 it was one agent, from 4-midnight it was another. So far I've tried using a numbers table, row numbers, goofy date math, and I'm at a loss. Any suggestions on how to handle this purely from sql code? If it helps, the table should always be small, like less than 20 never over 100. update After a few hours all I've managed to come up with is the below. It doesn't handle filling in days not available or times, just rotates through all the sales agents with leadTable as ( select leadid,userid,[order],StartDate, case DATEPART(dw,getdate()) when 1 then sunday when 2 then monday when 3 then tuesday when 4 then wednesday when 5 then thursday when 6 then friday when 7 then saturday end as DayAvailable , ROW_NUMBER() OVER (ORDER BY [order] ASC) AS ROWID from LeadSchedule where GETDATE()>=StartDate and (CONVERT(time(0),GETDATE())>= StartTime or StartTime is null) and (CONVERT(time(0),GETDATE())<= EndTime or EndTime is null) ) select userid, DATEADD(d,(number+ROWID-2)*totalUsers,startdate ) leadday from (select *, (select COUNT(1) from leadTable) totalUsers from leadTable inner join Numbers on 1=1 where DayAvailable =1 ) tb1 order by leadday asc

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  • show/hide html table columns using css

    - by Art Peterson
    I want to display a basic html table with controls to toggle showing/hiding of additional columns: <table id="mytable"> <tr> <th>Column 1</th> <th class="col1">1a</th> <th class="col1">1b</th> <th>Column 2</th> <th class="col2">2a</th> <th class="col2">2b</th> </tr> <tr> <td>100</td> <td class="col1">40</td> <td class="col1">60</td> <td>200</td> <td class="col2">110</td> <td class="col2">90</td> </tr> </table> So Column 1 and Column 2 will be the only columns displayed by default - but when you click on the Column 1 I want 1a and 1b to toggle, and same with Column 2 with 2a and 2b. I may end up with more columns and lots of rows - so any javascript looping approaches have been too slow to work with when I tested. The only approach that seems to be fast enough is to set up some css like this: table.hide1 .col1 { display: none; } table.hide2 .col2 { display: none; } table.hide3 .col3 { display: none; } table.show1 .col1 { display: table-cell; } table.show2 .col2 { display: table-cell; } table.show3 .col3 { display: table-cell; } And then set up onClick function calls on the table header cells that will trigger a toggle - and determine which css class to set "mytable" to that will create the toggle effect that I'm looking for. Is there an easy way to set this up so that the code can work for n # of columns?

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  • java timer on current instance

    - by hspim
    import java.util.Scanner; import java.util.Timer; import java.util.TimerTask; public class Boggle { Board board; Player player; Timer timer; boolean active; static Scanner in = new Scanner(System.in); public Boggle() { board = new Board(4); timer = new Timer(); } public void newGame() { System.out.println("Please enter your name: "); String line = in.nextLine(); player = new Player(line); active = true; board.shuffle(); System.out.println(board); timer.schedule(new timesUP(), 20000); while(active) { String temp = in.nextLine(); player.addGuess(temp); } } public void endGame() { active = false; int score = Scoring.calculate(player, board); System.out.println(score); } class timesUP extends TimerTask { public void run() { endGame(); } } public static void main(String[] args) { Boggle boggle = new Boggle(); boggle.newGame(); } } I have the above class which should perform a loop for a given length of time and afterwards invoke an instance method. Essentially I need the loop in newGame() to run for a minute or so before endGame() is invoked on the current instance. However, using the Timer class I'm not sure how I would invoke the method I need on the current instance since I can't pass any parameters to the timertasks run method? Is there an easy way to do this or am I going about this the wrong way? (note: this is a console project only, no GUI) ========== code edited I've changed the code to the above following the recommendations, and it works almost as I expect however the thread still doesnt seem to end properly. I was the while loop would die and control would eventually come back to the main method. Any ideas?

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  • sendmail and MX records when mail server is not on web host

    - by Jim Nelson
    This is a problem I'm sure is easy to fix, but I've been banging my head on it all day. I'm developing a new web site for a client. The web site resides at (this is an example) website.com. I have a PHP form script to email visitors' requests to [email protected]. When I coded this on a staging server on a different domain, all worked fine. When I moved it to website.com, the mail messages never arrived. The web server is on a virtual host with a major ISP. Here's what I've learned since then: My client's mail server is Microsoft Exchange on a box physically in their office. Whenever someone on the outside world emails [email protected], the mail arrives. But if the web server sends to the same email address, it fails every time. This is not a PHP problem. I secure shell in to the web server and have tested this both with sendmail and the UNIX mail application. I've also tested it by emailing various email accounts from the shell. I can email myself, for example, just nobody at the website.com domain. In short, when I'm logged in to website.com, mail to [email protected], [email protected], [email protected] all fail. All other addresses work fine. What I've discovered is those dropped emails are routed to the web server's "catchall" account where they sit in its inbox. I've done an MX lookup on website.com. The MX record points to mailsec.website.com. I can telnet to mailsec.website.com port 25 and see the SMTP server. It appears to me that website.com isn't doing an MX lookup when it's sending mail to [email protected]. My theory is that it recognizes the domain as local, sees that there's no "requests" user account to deliver it to, and drops the mail into the catchall account. What I want is to force sendmail to do the MX lookup and send the message on to the Exchange server. I'm at wit's end here. I can't figure out how to do this. For that matter, I may be way off base here and have misdiagnosed this entirely. Internet mail and MX has always seemed a black art to me, and my ignorance is certainly showing in this question.

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  • Discovering a functional algorithm from a mutable one

    - by Garrett Rowe
    This isn't necessarily a Scala question, it's a design question that has to do with avoiding mutable state, functional thinking and that sort. It just happens that I'm using Scala. Given this set of requirements: Input comes from an essentially infinite stream of random numbers between 1 and 10 Final output is either SUCCEED or FAIL There can be multiple objects 'listening' to the stream at any particular time, and they can begin listening at different times so they all may have a different concept of the 'first' number; therefore listeners to the stream need to be decoupled from the stream itself. Pseudocode: if (first number == 1) SUCCEED else if (first number >= 9) FAIL else { first = first number rest = rest of stream for each (n in rest) { if (n == 1) FAIL else if (n == first) SUCCEED else continue } } Here is a possible mutable implementation: sealed trait Result case object Fail extends Result case object Succeed extends Result case object NoResult extends Result class StreamListener { private var target: Option[Int] = None def evaluate(n: Int): Result = target match { case None => if (n == 1) Succeed else if (n >= 9) Fail else { target = Some(n) NoResult } case Some(t) => if (n == t) Succeed else if (n == 1) Fail else NoResult } } This will work but smells to me. StreamListener.evaluate is not referentially transparent. And the use of the NoResult token just doesn't feel right. It does have the advantage though of being clear and easy to use/code. Besides there has to be a functional solution to this right? I've come up with 2 other possible options: Having evaluate return a (possibly new) StreamListener, but this means I would have to make Result a subtype of StreamListener which doesn't feel right. Letting evaluate take a Stream[Int] as a parameter and letting the StreamListener be in charge of consuming as much of the Stream as it needs to determine failure or success. The problem I see with this approach is that the class that registers the listeners should query each listener after each number is generated and take appropriate action immediately upon failure or success. With this approach, I don't see how that could happen since each listener is forcing evaluation of the Stream until it completes evaluation. There is no concept here of a single number generation. Is there any standard scala/fp idiom I'm overlooking here?

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  • My style/control template out my calendar's blackout dates.

    - by Chris
    Howdy, My C#/WPF project needs a calendar. We're going to be using it to pick a range of dates for appointment scheduling. I'm told the default calendar is too small to be used by some of our reps so I've been working on resizing it. <toolkit:Calendar Grid.Row="1" x:Name="DateWindowCalendar" BorderBrush="White" BorderThickness="0" Style="{StaticResource PopupCalendarStyle}" DisplayMode="Month" SelectionMode="SingleRange" DisplayDateStart="{Binding FirstDayOfMonth}" AutomationProperties.AutomationId="ToolkitCalendarId" VerticalAlignment="Top"> </toolkit:Calendar> And I've created this styling: <Style x:Key="PopupCalendarStyle" TargetType="toolkit:Calendar"> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="toolkit:Calendar"> <StackPanel Margin="0" HorizontalAlignment="Center" x:Name="Root"> <toolkit:Calendar x:Name="Calendar" SelectedDate="{TemplateBinding SelectedDate}" DisplayDateStart="{TemplateBinding DisplayDateStart}" SelectionMode="{TemplateBinding SelectionMode}" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" SelectedDatesChanged="Calendar_SelectedDatesChanged"> <toolkit:Calendar.CalendarDayButtonStyle> <Style> <Setter Property="Button.Height" Value="34"/> <Setter Property="Button.Width" Value="34" /> <Setter Property="Button.FontSize" Value="16" /> </Style> </toolkit:Calendar.CalendarDayButtonStyle> <toolkit:Calendar.CalendarButtonStyle> <Style> <Setter Property="Button.Height" Value="34"/> <Setter Property="Button.Width" Value="34"/> <Setter Property="Button.FontSize" Value="16"/> </Style> </toolkit:Calendar.CalendarButtonStyle> </toolkit:Calendar> </StackPanel> </ControlTemplate> </Setter.Value> </Setter> </Style> Everything is almost perfect. I specify my range, I can track the selected dates (granted using the SelectedDatesChanged event instead of the SelectedDates property. The problem is I also need to be able to set blackout dates (usually the period between first of the month and today although sometimes first of the month to a few days from now). Without the styling, this works: DateWindowCalendar.BlackoutDates.Add(new CalendarDateRange( new DateTime(DateTime.Now.Year, DateTime.Now.Month, 01), DateTime.Now)); But when I add the style, I don't get the black out displays being displayed and worse its possible to select the blackout dates. I'm not sure what I missed but I'm hoping someone has an easy answer so that I don't have to rebuild the entire widget. Any help is appreciated. Thanks, Chris

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  • Want to set 'src' of script to my IP-Won't load in Safari or Chrome. Relative link asp.netmvc

    - by Ozaki
    I have a script that links to the server I am hosting (IP can change) usually I would just use for links: var url ='http://' + window.location.hostname + 'end of url'; But in this case it isnt appearing to be so easy. I have tried: (1) $('#scriptid').attr('src', url); as well as: (2) var script = document.createElement( 'script' ); script.type = 'text/javascript'; script.src = url; $("#insert").append( script ); Now case (2) works loads the script runs the script. But when at the end of my script it hits the 'write data' it decides to replace the entire page with just the data. Any idea on how I can do this? Note: I am using plain html not ASP. With ASP backend that is just the way it has to be. Ok it now is <script src="myscript.js"></script> C# router.AddAsyncRoute("myscript.js"...... It workes in IE & FF. But I get blank pages in Chrome & Safari. I am using document.write to write a script onto my page. Any ideas why Chrome & Safari don't like this? I am so far assuming that in Crhome & Safari it takes longer to run the script therefore launching the document.write after the DOM has loaded therefore replacing the page with a blank one. edit the script im trying to run is a modification of: d = new dTree('d'); d.add(0,-1,'My example tree'); d.add(1,0,'Node 1','default.html'); d.add(2,0,'Node 2','default.html'); d.add(3,1,'Node 1.1','default.html'); d.add(4,0,'Node 3','default.html'); d.add(5,3,'Node 1.1.1','default.html') document.write(d); Any ideas how I can get around this? I am not to sure how to implement an appenChild in this case as the script is changing constantly with live data. So every refresh it will generally have changed some...

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  • With NHibernate, how can I create an INHibernateProxy?

    - by Eric
    After lots of reading about serialization, I've decided to try to create DTOs. After more reading, I decided to use AutoMapper. What I would like to do is transform the parent (easy enough) and transform the entity properties if they've been initialized, which I've done with ValueResolvers like below (I may try to make it generic once I get it fully working). This part works. public class OrderItemResolver : ValueResolver<Order, OrderItem> { protected override OrderItem ResolveCore(Order source) { // could also use NHibernateUtil.IsInitialized(source.OrderItem) if (source.OrderItem is NHibernate.Proxy.INHibernateProxy) return null; else return source.OrderItem; } } } When I transform the DTO back to an entity, for the entities that weren't initialized, I want to create a proxy so that if the entity wants to access it, it can. However, I can't figure out how to create a proxy. I'm using Castle if that's relevant. I've tried a bunch of things with no luck. The below code is a mess, mainly because I've been trying things at random without knowing what I should be doing. Anybody have any suggestions? public class OrderItemDTOResolver : ValueResolver<OrderDTO, OrderItem> { protected override OrderItem ResolveCore(OrderDTO source) { if (source.OrderItem == null) { //OrderItem OrderItem = new ProxyGenerator().CreateClassProxy<OrderItem>(); // Castle.Core.Interceptor. //OrderItem OrderItem = new ProxyGenerator().CreateClassProxy<OrderItem>(); //OrderItem.Id = source.OrderItemId; //OrderItem OrderItem = new OrderItem(); //var proxy = new OrderItem() as INHibernateProxy; //var proxy = OrderItem as INHibernateProxy; //return (OrderItem)proxy.HibernateLazyInitializer //ILazyInitializer proxy = new LazyInitializer("OrderItem", OrderItem, source.OrderItemId, null, null, null, null); //return (OrderItem)proxy; //return (OrderItem)proxy.HibernateLazyInitializer.GetImplementation(); //return OrderItem; IProxyTargetAccessor proxy = new Castle.Core.Interceptor. var initializer = new LazyInitializer("OrderItem", typeof(OrderItem), source.OrderItemId, null, null, null, null); //var proxyFactory = new SerializableProxyFactory{Interfaces = Interfaces, TargetSource = initializer, ProxyTargetType = IsClassProxy}; //proxyFactory.AddAdvice(initializer); //object proxyInstance = proxyFactory.GetProxy(); //return (INHibernateProxy) proxyInstance; return null; //OrderItem.Id = source.OrderItemId; //return OrderItem; } else return OrderItemDTO.Unmap(source.OrderItem); } } Thanks, Eric

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  • SQLite bulk insert on iPhone not working

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

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  • Information Gain and Entropy

    - by dhorn
    I recently read this question regarding information gain and entropy. I think I have a semi-decent grasp on the main idea, but I'm curious as what to do with situations such as follows: If we have a bag of 7 coins, 1 of which is heavier than the others, and 1 of which is lighter than the others, and we know the heavier coin + the lighter coin is the same as 2 normal coins, what is the information gain associated with picking two random coins and weighing them against each other? Our goal here is to identify the two odd coins. I've been thinking this problem over for a while, and can't frame it correctly in a decision tree, or any other way for that matter. Any help? EDIT: I understand the formula for entropy and the formula for information gain. What I don't understand is how to frame this problem in a decision tree format. EDIT 2: Here is where I'm at so far: Assuming we pick two coins and they both end up weighing the same, we can assume our new chances of picking H+L come out to 1/5 * 1/4 = 1/20 , easy enough. Assuming we pick two coins and the left side is heavier. There are three different cases where this can occur: HM: Which gives us 1/2 chance of picking H and a 1/4 chance of picking L: 1/8 HL: 1/2 chance of picking high, 1/1 chance of picking low: 1/1 ML: 1/2 chance of picking low, 1/4 chance of picking high: 1/8 However, the odds of us picking HM are 1/7 * 5/6 which is 5/42 The odds of us picking HL are 1/7 * 1/6 which is 1/42 And the odds of us picking ML are 1/7 * 5/6 which is 5/42 If we weight the overall probabilities with these odds, we are given: (1/8) * (5/42) + (1/1) * (1/42) + (1/8) * (5/42) = 3/56. The same holds true for option B. option A = 3/56 option B = 3/56 option C = 1/20 However, option C should be weighted heavier because there is a 5/7 * 4/6 chance to pick two mediums. So I'm assuming from here I weight THOSE odds. I am pretty sure I've messed up somewhere along the way, but I think I'm on the right path! EDIT 3: More stuff. Assuming the scale is unbalanced, the odds are (10/11) that only one of the coins is the H or L coin, and (1/11) that both coins are H/L Therefore we can conclude: (10 / 11) * (1/2 * 1/5) and (1 / 11) * (1/2) EDIT 4: Going to go ahead and say that it is a total 4/42 increase.

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  • What are the Options for Storing Hierarchical Data in a Relational Database?

    - by orangepips
    Good Overviews One more Nested Intervals vs. Adjacency List comparison: the best comparison of Adjacency List, Materialized Path, Nested Set and Nested Interval I've found. Models for hierarchical data: slides with good explanations of tradeoffs and example usage Representing hierarchies in MySQL: very good overview of Nested Set in particular Hierarchical data in RDBMSs: most comprehensive and well organized set of links I've seen, but not much in the way on explanation Options Ones I am aware of and general features: Adjacency List: Columns: ID, ParentID Easy to implement. Cheap node moves, inserts, and deletes. Expensive to find level (can store as a computed column), ancestry & descendants (Bridge Hierarchy combined with level column can solve), path (Lineage Column can solve). Use Common Table Expressions in those databases that support them to traverse. Nested Set (a.k.a Modified Preorder Tree Traversal) First described by Joe Celko - covered in depth in his book Trees and Hierarchies in SQL for Smarties Columns: Left, Right Cheap level, ancestry, descendants Compared to Adjacency List, moves, inserts, deletes more expensive. Requires a specific sort order (e.g. created). So sorting all descendants in a different order requires additional work. Nested Intervals Combination of Nested Sets and Materialized Path where left/right columns are floating point decimals instead of integers and encode the path information. Bridge Table (a.k.a. Closure Table: some good ideas about how to use triggers for maintaining this approach) Columns: ancestor, descendant Stands apart from table it describes. Can include some nodes in more than one hierarchy. Cheap ancestry and descendants (albeit not in what order) For complete knowledge of a hierarchy needs to be combined with another option. Flat Table A modification of the Adjacency List that adds a Level and Rank (e.g. ordering) column to each record. Expensive move and delete Cheap ancestry and descendants Good Use: threaded discussion - forums / blog comments Lineage Column (a.k.a. Materialized Path, Path Enumeration) Column: lineage (e.g. /parent/child/grandchild/etc...) Limit to how deep the hierarchy can be. Descendants cheap (e.g. LEFT(lineage, #) = '/enumerated/path') Ancestry tricky (database specific queries) Database Specific Notes MySQL Use session variables for Adjacency List Oracle Use CONNECT BY to traverse Adjacency Lists PostgreSQL ltree datatype for Materialized Path SQL Server General summary 2008 offers HierarchyId data type appears to help with Lineage Column approach and expand the depth that can be represented.

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  • Collision point of 2 curves in a 3d-room

    - by Frank
    Hello, i am programming a small game for quite some time. We started coding a small FPS-Shooter inside of a project at school to get a bit experience using directX. I dont know why, but i couldnt stop the project and started programming at home aswell. At the moment i am trying to create some small AI. Of cause thats definatlly not easy, but thats my personal goal anyways. The topic could prolly fill multiple books hehe. I've got the walking part of my bots done so far. They walk along a scriped path. I am not working on the "aiming" of the bots. While programming that i hit on some math problem i couldnt solve yet. I hope of your input on this to help me get further. Concepts, ideas and everything else are highly appreciated. Problem: Calculate the position (D3DXVECTOR3) where the curve of the projectile (depends on gravity, speed), hit the curved of the enemys walking path (depends on speed). We assume that the enemy walks in a constant line. Known variables: float projectilSpeed = 2000 m/s //speed of the projectile per second float gravitation = 9.81 m/s^2 //of cause the gravity lol D3DXVECTOR3 targetPosition //position of the target stored in a vector (x,y,z) D3DXVECTOR3 projectilePosition //position of the projectile D3DXVECTOR3 targetSpeed //stores the change of the targets position in the last second Variabledefinition ProjectilePosition at time of collision = ProjectilePos_t TargetPosition at time of collision = TargetPos_t ProjectilePosition at time 0, now = ProjectilePos_0 TargetPosition at time 0, now = TargetPos_0 Time to impact = t Aim-angle = theta My try: Found a formular to calculate "drop" (Drop of the projectile based on the gravity) on Wikipedia: float drop = 0.5f * gravity * t * t The speed of the projectile has a horizontal and a vertical part.. Found a formular for that on wikipedia aswell: ProjectilVelocity.x = projectilSpeed * cos(theta) ProjectilVelocity.y = projectilSpeed * sin(theta) So i would assume this is true for the projectile curve: ProjectilePos_t.x = ProjectilePos_0.x + ProjectileSpeed * t ProjectilePos_t.y = ProjectilePos_0.y + ProjectileSpeed * t + 0.5f * gravity * t * t ProjectilePos_t.z = ProjectilePos_0.z + ProjectileSpeed * t The target walk with a constant speed, so we can determine his curve by this: TargetPos_t = TargetPos_0 + TargetSpeed * D3DXVECTOR3(t, t, t) Now i dont know how to continue. I have to solve it somehow to get a hold on the time to impact somehow. As a basic formular i could use: float time = distanz / projectileSpeed But that wouldnt be truly correct as it would assume a linear "Trajectory". We just find this behaivor when using a rocket. I hope i was able to explain the problem as much as possible. If there are questions left, feel free to ask me! Greets from germany, Frank

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  • Virtual member call in a constructor when assigning value to property

    - by comecme
    I have an Abstract class and a Derived class. The abstract class defines an abstract property named Message. In the derived class, the property is implemented by overriding the abstract property. The constructor of the derived class takes a string argument and assigns it to its Message property. In Resharper, this assignment leads to a warning "Virtual member call in constructor". The AbstractClass has this definition: public abstract class AbstractClass { public abstract string Message { get; set; } protected AbstractClass() { } public abstract void PrintMessage(); } And the DerivedClass is as follows: using System; public class DerivedClass : AbstractClass { private string _message; public override string Message { get { return _message; } set { _message = value; } } public DerivedClass(string message) { Message = message; // Warning: Virtual member call in a constructor } public DerivedClass() : this("Default DerivedClass message") {} public override void PrintMessage() { Console.WriteLine("DerivedClass PrintMessage(): " + Message); } } I did find some other questions about this warning, but in those situations there is an actual call to a method. For instance, in this question, the answer by Matt Howels contains some sample code. I'll repeat it here for easy reference. class Parent { public Parent() { DoSomething(); } protected virtual void DoSomething() {}; } class Child : Parent { private string foo; public Child() { foo = "HELLO"; } protected override void DoSomething() { Console.WriteLine(foo.ToLower()); } } Matt doesn't describe on what error the warning would appear, but I'm assuming it will be on the call to DoSomething in the Parent constructor. In this example, I understand what is meant by a virtual member being called. The member call occurs in the base class, in which only a virtual method exists. In my situation however, I don't see why assigning a value to Message would be calling a virtual member. Both the call to and the implementation of the Message property are defined in the derived class. Although I can get rid of the error by making my Derived Class sealed, I would like to understand why this situation is resulting in the warning.

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  • Components are not longer resizable after moving

    - by Junior Software Developer
    Hi guys My question relates to swing programming. I want to enlarge a component (component x) by removing it from its parent panel (component a) and adding it in one of component a's parent (component b). Before that, I call setVisible(false) on all components in b. After that I want to make this back by removing it from b and adding on a. After that all components are not longer resizable. Why that? An easy example: import java.awt.BorderLayout; import java.awt.Color; import java.awt.Component; import java.awt.Dimension; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JTabbedPane; public class SwingTest { private static ViewPanel layer1; private static JFrame frame; private static JTabbedPane tabbedPane; private static ViewPanel root; public static void main(String[] args) { frame = new JFrame(); frame.setLayout(new BorderLayout()); frame.setMinimumSize(new Dimension(800, 600)); root = new ViewPanel(); root.setBackground(Color.blue); root.setPreferredSize(new Dimension(400, 600)); root.setLayout(new BorderLayout()); root.add(new JLabel("blue area")); layer1 = new ViewPanel(); layer1.setBackground(Color.red); layer1.setPreferredSize(new Dimension(400, 600)); layer1.setLayout(new BorderLayout()); tabbedPane = new JTabbedPane(); tabbedPane.add("A", new JLabel("A label")); tabbedPane.setPreferredSize(new Dimension(400, 600)); layer1.add(tabbedPane); root.add(layer1); frame.add(root, BorderLayout.NORTH); frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); frame.pack(); frame.setVisible(true); Thread t = new Thread() { @Override public void run() { try { Thread.sleep(8000); System.out.println("start"); for (Component c : root.getComponents()) { c.setVisible(false); } layer1.remove(tabbedPane); root.add(tabbedPane); Thread.sleep(8000); root.remove(tabbedPane); layer1.add(tabbedPane); for (Component c : root.getComponents()) { c.setVisible(true); c.repaint(); } } catch (InterruptedException e) { //... } } }; t.start(); } }

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  • javascript DOM how to know what node is?

    - by Fernando SBS
    here is the source code: <table id="movements" cellpadding="1" cellspacing="1"><thead><tr><th colspan="3">Movimentações de tropas:</th></tr></thead><tbody><tr> <td class="typ"><a href="build.php?gid=16"><img src="img/x.gif" class="att1" alt="Tropas atacantes chegando" title="Tropas atacantes chegando" /></a><span class="a1">&raquo;</span></td> <td><div class="mov"><span class="a1">1&nbsp;Ataque</span></div><div class="dur_r">em&nbsp;<span id="timer1">13:21:06</span>&nbsp;hrs.</div></div></td></tr><tr> <td class="typ"><a href="build.php?gid=16"><img src="img/x.gif" class="def1" alt="Tropas de reforço chegando" title="Tropas de reforço chegando" /></a><span class="d1">&raquo;</span></td> <td><div class="mov"><span class="d1">1&nbsp;Reforço</span></div><div class="dur_r">em&nbsp;<span id="timer2">0:14:55</span>&nbsp;hrs.</div></div></td></tr><tr> <td class="typ"><a href="build.php?gid=16"><img src="img/x.gif" class="att2" alt="Próprias tropas atacando" title="Próprias tropas atacando" /></a><span class="a2">&laquo;</span></td> <td><div class="mov"><span class="a2">1&nbsp;Ataque</span></div><div class="dur_r">em&nbsp;<span id="timer3">0:08:50</span>&nbsp;hrs.</div></div></td></tr><tr> <td class="typ"><a href="build.php?gid=16"><img src="img/x.gif" class="def2" alt="Próprias tropas reforçando" title="Próprias tropas reforçando" /></a><span class="d2">&laquo;</span></td> <td><div class="mov"><span class="d2">1&nbsp;Reforço</span></div><div class="dur_r">em&nbsp;<span id="timer4">2:50:45</span>&nbsp;hrs.</div></div></td></tr></tbody></table> and this is the View Source Chart of the document html (for easy DOM working): I would like to get to the 0:14:55 value coming from <span class="d1">, how to do it? EDIT Marcel Korpel: The value is always in the span in a div coming directly after a div containing a span with class d1, like: <div class="mov"><span class="d1">1&nbsp;Reforço</span></div><div class="dur_r">em&nbsp;<span id="timer2">0:14:55</span>&nbsp;hrs.</div>

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  • how can we make class with Linked list recursion ...

    - by epsilon_G
    Hi , I'm newbee in The C++ heaven and the OOP, ... I'd like to make some stuffs with the Data structures ... However,I'd like to merge two linked listes ... I made a class before "List" wich contain all what I need to programme something with List ... Add , Display .. The probleme is that I programmed the function "Merge2lists" which give us the third list .. How can I display the third list in the main program after using "Merge2lists" Plz , my prob with the Class and the OOP syntaxe ... try to give me the implementation in the main program ??? Otherwise,How can I apply function given pointer in main program wich declared in class .. Thankx class Liste { private: struct node { int elem ; node *next; }*p; public: LLC(); void Merge2lists (node* a, node * b,node *&result); ~LLC(); }; void List::Merge2lists (node* a, node * b,node *&result) { result = NULL; if (a==NULL) { result=b; return;} else if (b==NULL) { result=a; return;} if (a->elem <= b->elem) { result = a; Merge2lists(a->next, b,result->next); } else { result = b; Merge2lists(a, b->next,result->next); } return; } int main() { liste a ; a.Aff_Val(46); a.Aff_Val(54); a.add_as_first(2); a.add_as_first(1); a.Display(); /*This to displat the elemnts ... Don't care about it it's easy to make*/ list liste2; b.Add(2); b.Add(14); b.Add(16); list result; Merge2lists (a,b,result); /*The probleme is here , how can I use this in my program */

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  • Summarising (permanently) data in a SQL table

    - by Cylindric
    Geetings, Stackers. I have a huge number of data-points in a SQL table, and I want to summarise them in a way reminiscent of RRD. Assuming a table such as ID | ENTITY_ID | SCORE_DATE | SCORE | SOME_OTHER_DATA ----+-----------+------------+-------+----------------- 1 | A00000001 | 01/01/2010 | 100 | some data 2 | A00000002 | 01/01/2010 | 105 | more data 3 | A00000003 | 01/01/2010 | 104 | various text ... | ......... | .......... | ..... | ... ... | A00009999 | 01/01/2010 | 101 | ... | A00000001 | 02/01/2010 | 104 | ... | A00000002 | 02/01/2010 | 119 | ... | A00000003 | 02/01/2010 | 119 | ... | ......... | .......... | ..... | ... | A00009999 | 02/01/2010 | 101 | arbitrary data ... | ......... | .......... | ..... | ... ... | A00000001 | 01/02/2010 | 104 | ... | A00000002 | 01/02/2010 | 119 | ... | A00000003 | 01/01/2010 | 119 | I want to end up with one record per entity, per month: ID | ENTITY_ID | SCORE_DATE | SCORE | ----+-----------+------------+-------+ ... | A00000001 | 01/01/2010 | 100 | ... | A00000002 | 01/01/2010 | 105 | ... | A00000003 | 01/01/2010 | 104 | ... | A00000001 | 01/02/2010 | 100 | ... | A00000002 | 01/02/2010 | 105 | ... | A00000003 | 01/02/2010 | 104 | (I Don't care about the SOME_OTHER_DATA - I'll pick something - either the first or last record probably.) What's an easy way of doing this on a regular basis, so that anything in the last calendar month is summarised in this way? At the moment my plan is kind of: For each EntityID For each month Find average score for all records in given month Update first record with results of previous step Delete all records that aren't the first I can't think of a neat way of doing it though, that doesn't involve lots of updates and iteration. This can either be done in a SQL Stored Procedure, or it can be incorporated into the .Net app that's generating this data, so the solution doesn't really need to be "one big SQL script", but can be :) (SQL-2005)

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  • Uncaught TypeError: Cannot read property 'length' of undefined

    - by AnApprentice
    I'm working to built a contact list that is grouped by the first letter of the contact's last name. After a succesfull ajax request, the contact is pushed to addContact: Ajax success: ko.utils.arrayForEach(dataJS.contactList, function(c) { contactsModel.addContact(c); }); contactsModel.addContact: //add a contact in the right spot under the right letter contactsModel.addContact = function(newContact) { //grab first character var firstLetter = (newContact.lname || "").charAt(0).toUpperCase(); //if it is a number use # if (!isNaN(firstLetter)) { firstLetter = "#"; } //do we already have entries for this letter if (!this.letterIndex[firstLetter]) { //new object to track this letter's contacts var letterContacts = { letter: firstLetter, contacts: ko.observableArray([]) }; this.letterIndex[firstLetter] = letterContacts; //easy access to it //put the numbers at the end if (firstLetter === "#") { this.contactsByLetter.push(letterContacts); } else { //add the letter in the right spot for (var i = 0, lettersLength = this.contactsByLetter().length; i < lettersLength; i++) { var letter = this.contactsByLetter()[i].letter; if (letter === "#" || firstLetter < letter) { break; } } this.contactsByLetter.splice(i, 0, letterContacts); } } var contacts = this.letterIndex[firstLetter].contacts; //now we have a letter to add our contact to, but need to add it in the right spot var newContactName = newContact.lname + " " + newContact.fname; for (var j = 0, contactsLength = contacts().length; j < contactsLength; j++) { var contactName = contacts()[j].lName + " " + contacts()[j].fName; if (newContactName < contactName) { break; } } //add the contact at the right index contacts.splice(j, 0, newContact); }.bind(contactsModel); The contacts json object from the server looks like this: { "total_pages": 10, "page": page, "contactList": [{ "photo": "http://homepage.mac.com/millhouse/Family%20Tree/images/PersonListIcon.png", "lname": "Bond", "id": 241, "fname": "James", "email": "[email protected]"}, While this works in jsfiddle, when I try it locally, I get the following error during the first push to addContact: Uncaught TypeError: Cannot read property 'length' of undefined jQuery.jQuery.extend._Deferred.deferred.resolveWithjquery-1.5.1.js:869 donejquery-1.5.1.js:6591 jQuery.ajaxTransport.send.callbackjquery-1.5.1.js:7382 Ideas? Thanks

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  • Move options between multiple lists

    - by Martha
    We currently have a form with the standard multi-select functionality of "here are the available options, here are the selected options, here are some buttons to move stuff back and forth." However, the client now wants the ability to not just select certain items, but to also categorize them. For example, given a list of books, they want to not just select the ones they own, but also the ones they've read, the ones they would like to read, and the ones they've heard about. (All examples fictional.) Thankfully, a selected item can only be in one category at a time. I can find many examples of moving items between listboxes, but not a single one for moving items between multiple listboxes. To add to the complication, the form needs to have two sets of list+categories, e.g. a list of movies that need to be categorized in addition to the aforementioned books. EDIT: Having now actually sat down to try to code the non-javascripty bits, I need to revise my question, because I realized that multiple select lists won't really work from the "how do I inform the server about all this lovely new information" standpoint. So the html code is now a pseudo-listbox, i.e. an unordered list (ul) displayed in a box with a scrollbar, and each list item (<li>) has a set of five radio buttons (unselected/own/read/like/heard). My task is still roughly the same: how to take this one list and make it easy to categorize the items, in such a way that the user can tell at a glance what is in what category. (The pseudo-listbox has some of the same disadvantages as a multi-select listbox, namely it's hard to tell what's selected if the list is long enough to scroll.) The dream solution would be a drag-and-drop type thing, but at this point even buttons would be OK. Another modification (a good one) is that the client has revised the lists, so the longest is now "only" 62 items long (instead of the many hundreds they had before). The categories will still mostly contain zero, one, or two selected items, possibly a couple more if the user was overzealous. As far as OS and stuff, the site is in classic asp (quit snickering!), the server-side code is VBScript, and so far we've avoided the various Javascript libraries by the simple expedient of almost never using client-side scripting. This one form for this one client is currently the big exception. Give 'em an inch and they want a mile... Oh, and I have to add: I suck at Javascript, or really at any C-descendant language. Curly braces give me hives. I'd really, really like something I can just copy & paste into my page, maybe tweak some variable names, and never look at it again. A girl can dream, can't she? :) [existing code deleted because it's largely irrelevant.]

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  • If array is thread safe, what the issue with this function?

    - by Ajay Sharma
    I am totally lost with the things that is happening with my code.It make me to think & get clear with Array's thread Safe concept. Is NSMutableArray OR NSMutableDictionary Thread Safe ? While my code is under execution, the values for the MainArray get's changes although, that has been added to Array. Please try to execute this code, onyour system its very much easy.I am not able to get out of this Trap. It is the function where it is returning Array. What I am Looking to do is : -(Array) (Main Array) --(Dictionary) with Key Value (Multiple Dictionary in Main Array) ----- Above dictionary has 9 Arrays in it. This is the structure I am developing for Array.But even before #define TILE_ROWS 3 #define TILE_COLUMNS 3 #define TILE_COUNT (TILE_ROWS * TILE_COLUMNS) -(NSArray *)FillDataInArray:(int)counter { NSMutableArray *temprecord = [[NSMutableArray alloc] init]; for(int i = 0; i <counter;i++) { if([temprecord count]<=TILE_COUNT) { NSMutableDictionary *d1 = [[NSMutableDictionary alloc]init]; [d1 setValue:[NSString stringWithFormat:@"%d/2011",i+1] forKey:@"serial_data"]; [d1 setValue:@"Friday 13 Sep 12:00 AM" forKey:@"date_data"]; [d1 setValue:@"Description Details " forKey:@"details_data"]; [d1 setValue:@"Subject Line" forKey:@"subject_data"]; [temprecord addObject:d1]; d1= nil; [d1 release]; if([temprecord count]==TILE_COUNT) { NSMutableDictionary *holderKey = [[NSMutableDictionary alloc]initWithObjectsAndKeys:temprecord,[NSString stringWithFormat:@"%d",[casesListArray count]+1],nil]; [self.casesListArray addObject:holderKey]; [holderKey release]; holderKey =nil; [temprecord removeAllObjects]; } } else { [temprecord removeAllObjects]; NSMutableDictionary *d1 = [[NSMutableDictionary alloc]init]; [d1 setValue:[NSString stringWithFormat:@"%d/2011",i+1] forKey:@"serial_data"]; [d1 setValue:@"Friday 13 Sep 12:00 AM" forKey:@"date_data"]; [d1 setValue:@"Description Details " forKey:@"details_data"]; [d1 setValue:@"Subject Line" forKey:@"subject_data"]; [temprecord addObject:d1]; d1= nil; [d1 release]; } } return temprecord; [temprecord release]; } What is the problem with this Code ? Every time there are 9 records in Array, it just replaces the whole Array value instead of just for specific key Value.

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  • Audio/video streaming on Windows platform

    - by bushtucker
    I'm building an interactive language learning application to be used in a classroom environment. The idea is that a teacher should be able to talk to the students (=audio stream to all students), let students talk to each other (= audio P2P) in groups of two or more, let students watch a video coming from a the DVD player or coming from a media server. It should be possible to save the audio/video streams. The teacher should also be able to monitor, take-over or block the desktop of the students. The platform is Windows and it's a desktop application, no web application. The audio delay should be as minimal as poosible. Optionally a student sitting at home should be supported, but it's not a high priority. I am now finished with the classroom control part of the application (login, monitor, block, ...) and want to start the audio and video part. I've been evaluating several options like DirectX, GStreamer and SIP but now I have to make a decision. DirectX seems an obvious choice for the Windows platform, but it only lets me capture and playback audio and video. The encoding/decoding/network part I should do myself. GStreamer contains all kinds of options to capture/encode/stream/save audio and video streams. I've experimented a bit with it (ossbuild) and it does seem to involve a lot of trial and error to make something work: - microphone capture (via directsoundsrc) produces cracking noises on some computers - rtpL16 payloader didn't work well - streaming raw audio over the network only working at a sampling rate of 8000, no higher - there are a lot of errors when receiving mpeg4 video (bad I-frame), on some computers worse than others It is my impression that gstreamer is primary targetted at linux platforms. Development and support for the Windows platform seems to be a little behind. Nevertheless it's a powerful framework that could save me months and years of work. SIP seems to be able to do everything I want, but it is targeted towards telephony and IM. I don't know how flexible SIP is. It seems to me that the SIP layer would just be overhead as I already have a central (teacher) application that can control and setup all the streams. The interesting parts of frameworks like opalvoip and freeswitch are the actual audio/video capture, the encoding and transmission. Does anyone know how these interesting parts relate a framework like gstreamer? Are they easy to integrate into a custom application? Are they flexible enough? Does anyone have experience with all or one of these technologies? Maybe there are even other options I can look at? Many thanks for your advice

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  • Python/Biomolecular Physics- Trying to code a simple stochastic simulation of a system exhibiting co

    - by user359597
    *edited 6/17/10 I'm trying to understand how to improve my code (make it more pythonic). Also, I'm interested in writing more intuitive 'conditionals' that would describe scenarios that are commonplace in biochemistry. The conditional criteria in the below program is explained in Answer #2, but I am not satisfied with it- it is correct, but isn't obvious and isn't easy to implement for more complicated conditional scenarios. Ideas welcome. Comments/criticisms welcome. First posting experience @ stackoverflow- please comment on etiquette if needed. The code generates a list of values that are the solution to the following exercise: "In a programming language of your choice, implement Gillespie’s First Reaction Algorithm to study the temporal behaviour of the reaction A---B in which the transition from A to B can only take place if another compound, C, is present, and where C dynamically interconverts with D, as modelled in the Petri-net below. Assume that there are 100 molecules of A, 1 of C, and no B or D present at the start of the reaction. Set kAB to 0.1 s-1 and both kCD and kDC to 1.0 s-1. Simulate the behaviour of the system over 100 s." def sim(): # Set the rate constants for all transitions kAB = 0.1 kCD = 1.0 kDC = 1.0 # Set up the initial state A = 100 B = 0 C = 1 D = 0 # Set the start and end times t = 0.0 tEnd = 100.0 print "Time\t", "Transition\t", "A\t", "B\t", "C\t", "D" # Compute the first interval transition, interval = transitionData(A, B, C, D, kAB, kCD, kDC) # Loop until the end time is exceded or no transition can fire any more while t <= tEnd and transition >= 0: print t, '\t', transition, '\t', A, '\t', B, '\t', C, '\t', D t += interval if transition == 0: A -= 1 B += 1 if transition == 1: C -= 1 D += 1 if transition == 2: C += 1 D -= 1 transition, interval = transitionData(A, B, C, D, kAB, kCD, kDC) def transitionData(A, B, C, D, kAB, kCD, kDC): """ Returns nTransition, the number of the firing transition (0: A->B, 1: C->D, 2: D->C), and interval, the interval between the time of the previous transition and that of the current one. """ RAB = kAB * A * C RCD = kCD * C RDC = kDC * D dt = [-1.0, -1.0, -1.0] if RAB > 0.0: dt[0] = -math.log(1.0 - random.random())/RAB if RCD > 0.0: dt[1] = -math.log(1.0 - random.random())/RCD if RDC > 0.0: dt[2] = -math.log(1.0 - random.random())/RDC interval = 1e36 transition = -1 for n in range(len(dt)): if dt[n] > 0.0 and dt[n] < interval: interval = dt[n] transition = n return transition, interval if __name__ == '__main__': sim()

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  • What are the weaknesses of this user authentication method?

    - by byronh
    I'm developing my own PHP framework. It seems all the security articles I have read use vastly different methods for user authentication than I do so I could use some help in finding security holes. Some information that might be useful before I start. I use mod_rewrite for my MVC url's. Passwords are sha1 and md5 encrypted with 24 character salt unique to each user. mysql_real_escape_string and/or variable typecasting on everything going in, and htmlspecialchars on everything coming out. Step-by step process: Top of every page: session_start(); session_regenerate_id(); If user logs in via login form, generate new random token to put in user's MySQL row. Hash is generated based on user's salt (from when they first registered) and the new token. Store the hash and plaintext username in session variables, and duplicate in cookies if 'Remember me' is checked. On every page, check for cookies. If cookies set, copy their values into session variables. Then compare $_SESSION['name'] and $_SESSION['hash'] against MySQL database. Destroy all cookies and session variables if they don't match so they have to log in again. If login is valid, some of the user's information from the MySQL database is stored in an array for easy access. So far, I've assumed that this array is clean so when limiting user access I refer to user.rank and deny access if it's below what's required for that page. I've tried to test all the common attacks like XSS and CSRF, but maybe I'm just not good enough at hacking my own site! My system seems way too simple for it to actually be secure (the security code is only 100 lines long). What am I missing? I've also spent alot of time searching for the vulnerabilities with mysql_real_escape string but I haven't found any information that is up-to-date (everything is from several years ago at least and has apparently been fixed). All I know is that the problem was something to do with encoding. If that problem still exists today, how can I avoid it? Any help will be much appreciated.

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