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  • Multiple dynamic timers

    - by Rickard
    I am working on a project where I need to let the user create one (or more) timers to fire off an event. The user is supposed to define variables such as if the timer should be active and how often the timer will fire along with some other variables of what will happen when the timer is fiering. All these variables are stored in a dictionary (Disctionary) where the object holds all the variables the user has set and the string is the name that the user has chosen for this timer. I then want my program to loop through this dictionary and search for all objects which has the variable t_Active set to true (this I have already achieved). What I need help with figuring out is the follwoing: When it detects the variable, and if it's set to true, I need the program to see if there is already a timer created for this. If it isn't, it should create one and set the relevant parameters for the timer. The two variables t_num and t_period should decide the interval of the timer. t_num is an int and t_period is a string which will be set to either minutes, hours or days. Combining t_num with 60000 (minutes), 3600000 (hours) or 86400000 should give the corrct interval. But how would I go on about programatically create a timer for each user-defined active object? And how do I get the program to detect wether or not a timer has already been created? I have been searching both here and on google, but so far I haven't come across something that makes sense to me. I am still learning C#, so what make sense to you guys may not neccessarilly make sense to me yet. :) I hope I have explaned what I need good enough, please do ask me to clarify if you don't get me. Edit: Maybe I should also mention that the mentioned dictionary will also be saved to an XML file to that the user can pick up all the settings they made at any time.

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  • Sending emails in web applications

    - by Denise
    Hi everyone, I'm looking for some opinions here, I'm building a web application which has the fairly standard functionality of: Register for an account by filling out a form and submitting it. Receive an email with a confirmation code link Click the link to confirm the new account and log in When you send emails from your web application, it's often (usually) the case that there will be some change to the persistence layer. For example: A new user registers for an account on your site - the new user is created in the database and an email is sent to them with a confirmation link A user assigns a bug or issue to someone else - the issue is updated and email notifications are sent. How you send these emails can be critical to the success of your application. How you send them depends on how important it is that the intended recipient receives the email. We'll look at the following four strategies in relation to the case where the mail server is down, using example 1. TRANSACTIONAL & SYNCHRONOUS The sending of the email fails and the user is shown an error message saying that their account could not be created. The application will appear to be slow and unresponsive as the application waits for the connection timeout. The account is not created in the database because the transaction is rolled back. TRANSACTIONAL & ASYNCHRONOUS The transactional definition here refers to sending the email to a JMS queue or saving it in a database table for another background process to pick up and send. The user account is created in the database, the email is sent to a JMS queue for processing later. The transaction is successful and committed. The user is shown a message saying that their account was created and to check their email for a confirmation link. It's possible in this case that the email is never sent due to some other error, however the user is told that the email has been sent to them. There may be some delay in getting the email sent to the user if application support has to be called in to diagnose the email problem. NON-TRANSACTIONAL & SYNCHRONOUS The user is created in the database, but the application gets a timeout error when it tries to send the email with the confirmation link. The user is shown an error message saying that there was an error. The application is slow and unresponsive as it waits for the connection timeout When the mail server comes back to life and the user tries to register again, they are told their account already exists but has not been confirmed and are given the option of having the email re-sent to them. NON-TRANSACTIONAL & ASYNCHRONOUS The only difference between this and transactional & asynchronous is that if there is an error sending the email to the JMS queue or saving it in the database, the user account is still created but the email is never sent until the user attempts to register again. What I'd like to know is what have other people done here? Can you recommend any other solutions other than the 4 I've mentioned above? What's a reasonable way of approaching this problem? I don't want to over-engineer a system that's dealing with the (hopefully) rare situation where my mail server goes down! The simplest thing to do is to code it synchronously, but are there any other pitfalls to this approach? I guess I'm wondering if there's a best practice, I couldn't find much out there by googling.

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  • Constructing human readable sentences based on a survey

    - by Joshua
    The following is a survey given to course attendees to assess an instructor at the end of the course. Communication Skills 1. The instructor communicated course material clearly and accurately. Yes No 2. The instructor explained course objectives and learning outcomes. Yes No 3. In the event of not understanding course materials the instructor was available outside of class. Yes No 4. Was instructor feedback and grading process clear and helpful? Yes No 5. Do you feel that your oral and written skills have improved while in this course? Yes No We would like to summarize each attendees selection based on the choices chosen by him. If the provided answers were [No, No, Yes, Yes, Yes]. Then we would summarize this as "The instructor was not able to summarize course objectives and learning outcomes clearly, but was available for usually helpful outside of class. The instructor feedback and grading process was clear and helpful and I feel that my oral and written skills have improved because of this course. Based on the selections chosen by the attendee the summary would be quite different. This leads to many answers based on the choices selected and the number of such questions in the survey. The questions are usually provided by the training organization. How do you come up with a generic solution so that this can be effectively translated into a human readable form. I am looking for tools or libraries (java based), suggestions which will help me create such human readable output. I would like to hide the complexity from the end users as much as possible.

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  • Unit test for Web Forms MVP presenter has a null Model

    - by jacksonakj
    I am using Web Forms MVP to write an DotNetNuke user control. When the 'SubmitContactUs' event is raised in my unit test the presenter attempts to set the 'Message' property on the Modal. However the View.Modal is null in the presenter. Shouldn't the Web Forms MVP framework automatically build a new View.Model object in the presenter? It could be that the 'Arrange' portion of my test is missing something that the presenter needs. Any help would be appreciated. Here is my test: using System; using AthleticHost.ContactUs.Core.Presenters; using AthleticHost.ContactUs.Core.Views; using Xunit; using Moq; namespace AthleticHost.ContactUs.Tests { public class ContactUsPresenterTests { [Fact] public void ContactUsPresenter_Sets_Message_OnSubmit() { // Arrange var view = new Mock<IContactUsView>(); var presenter = new ContactUsPresenter(view.Object); // Act view.Raise(v => v.Load += null, new EventArgs()); view.Raise(v => v.SubmitContactUs += null, new SubmitContactUsEventArgs("Chester", "Tester", "[email protected]", "http://www.test.com", "This is a test of the emergancy broadcast system...")); presenter.ReleaseView(); // Assert Assert.Contains("Chester Tester", view.Object.Model.Message); } } }

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  • JQuery-UI Drag, Drop and Re-Drag Clones on Re-Drag

    - by amarcy
    I am using the following code to extend the JQuery-UI demos included with the download. I am trying to set up a container that the user can drag items into and then move the items around within the container. I incorporated the answer from http://stackoverflow.com/questions/867469/jquery-draggable-clone which works with one problem. <script> $(document).ready(function() { $("#droppable").droppable({ accept: '.ui-widget-content', drop: function(event, ui) { if($(ui).parent(":not(:has(#id1))")){ $(this).append($(ui.helper).clone().attr("id", "id1")); } $("#id1").draggable({ containment: 'parent', }); } }); $(".ui-widget-content").draggable({helper: 'clone'}); }); </script> div class="demo"> <div id="draggable" class="ui-widget-content"> <p>Drag me around</p> </div> <div id="droppable" class="ui-widget-header"> <p>Drop here</p> </div> When an item is dropped onto the droppable container it can be dragged one time and when it is dropped after that drag it loses its dragging capability. How do I allow for the item to be dragged multiple times after it has been added to the droppable container?

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  • update variable based upon results from .NET backgroundworker

    - by Bruce
    I've got a C# program that talks to an instrument (spectrum analyzer) over a network. I need to be able to change a large number of parameters in the instrument and read them back into my program. I want to use backgroundworker to do the actual talking to the instrument so that UI performance doesn't suffer. The way this works is - 1) send command to the instrument with new parameter value, 2) read parameter back from the instrument so I can see what actually happened (for example, I try to set the center frequency above the max that the instrument will handle and it tells me what it will actually handle), and 3) update a program variable with the actual value received from the instrument. Because there are quite a few parameters to be updated I'd like to use a generic routine. The part I can't seem to get my brain around is updating the variable in my code with what comes back from the instrument via backgroundworker. If I used a separate RunWorkerCompleted event for each parameter I could hardwire the update directly to the variable. I'd like to come up with a way of using a single routine that's capable of updating any of the variables. All I can come up with is passing a reference number (different for each parameter) and using a switch statement in the RunWorkerCompleted handler to direct the result. There has to be a better way.

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  • Dashcode code translation

    - by Alex Mcp
    Hi, a quick, probably easy question whose answer is probably "best practice" I'm following a tutorial for a custom-template mobile Safari webapp, and to change views around this code is used: function btnSave_ClickHandler(event) { var views = document.getElementById('stackLayout'); var front = document.getElementById('mainScreen'); if (views && views.object && front) { views.object.setCurrentView(front, true); } } My question is just about the if conditional statement. What is this triplet saying, and why do each of those things need to be verified before the view can be changed? Does views.object just test to see if the views variable responds to the object method? Why is this important? EDIT - This is/was the main point of this question, and it regards not Javascript as a language and how if loops work, but rather WHY these 3 things specifically need to be checked: Under what scenarios might views and front not exist? I don't typically write my code so redundantly. If the name of my MySQL table isn't changing, I'll just say UPDATE 'mytable' WHERE... instead of the much more verbose (and in my view, redundant) $mytable = "TheSQLTableName"; if ($mytable == an actual table && $mytable exists && entries can be updated){ UPDATE $mytable; } Whereas if the table's name (or in the JS example, the view's names) ARE NOT "hard coded" but are instead a user input or otherwise mutable, I might right my code as the DashCode example has it. So tell me, can these values "go wrong" anyhow? Thanks!

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  • Qt 4.x: how to implement drag-and-drop onto the desktop or into a folder?

    - by Jeremy Friesner
    Hi all, I've written a little file-transfer application written in C++ using Qt 4.x ... it logs into a server, shows the user a list of files available on the server, and lets the user upload or download files. This all works fine; you can even drag a file in from the desktop (or from an open folder), and when you drop the file icon into the server-files-list-view, the dropped file gets uploaded to the server. Now I have a request for the opposite action as well... my users would like to be able to drag a file out of the server-files-list-view and onto the desktop, or into an open folder window, and have that file get downloaded into that location. That seems like a reasonable request, but I don't know how to implement it. Is there a way for a Qt application to find out the directory corresponding to where "drop event" occurred, when the icon was dropped onto the desktop or into an open folder window? Ideally this would be a Qt-based platform-neutral mechanism, but if that doesn't exist, then platform-specific mechanisms for MacOS/X and Windows (XP or higher) would suffice. Any ideas?

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  • Calling javascript function on the Mousehoever and mouseout using jQuery

    - by Wazdesign
    I want to call the javascript function using mousehover jQuery event. Here is the one function. // On mouse hover function function ShowHighlighter(d, highlight_elid) { //alert ("ShowHighlighter\n"+d); if (d == "addHighlight") { var txt = getSelText(); if (txt.length < 1) { return; } ShowContent(d); } else if (d == "deleteHighlight") { var elid = "#"+d; jQuery(elid).stop(); ShowContent(d); delete_highlight_id = "#"+highlight_elid; } } // on Mouse out function function HideContent(d) { if(d.length < 1) { return; } document.getElementById(d).style.display = "none"; } I am trying to use this function ... but it not seems to be working. jQuery('a[href="HIGHLIGHT_CREATELINK"]').mouseover(ShowHighlighter("deleteHighlight","highlight"+ randomCount + ");) ; jQuery('a[href="HIGHLIGHT_CREATELINK"]').mouseout('javascript:HideContentFade(\"deleteHighlight\");') please help me out in this. thanks.

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  • ASP.net download page

    - by Russel
    Hi I have a Reports.aspx ASP.NET page that allows users to download excel report files by clicking on several hyperlinks. When a report hyperlink is clicked, I open a new window using the javascript window.open method and navigate off to the download.aspx page. The code-behind for the download page creates a excel file on the fly using openxml(in memory) and send it back to the browser. Here is some code from the download.aspx page: byte[] outputFileBytes = CreateExcelReport().ToArray(); Response.Clear(); Response.BufferOutput = true; Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"; Response.AddHeader("Content-Disposition", string.Format("attachment; filename={0}", "tempReport.xlsx")); Response.BinaryWrite(outputFileBytes); Response.Flush(); Response.Close(); Response.End(); My problem : Some of these reports take some time to generate. I would like to display a loading.gif file on my Reports.aspx page, while the download.aspx page is requested. Once the page request is completed, the loading.gif file should be made invisible. Is there a way to achieve this. Perhaps some kind of event. I have mootools to my disposal. Thanks PS. I know that generating reports like this is not ideal, but thats a different story all together...

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  • How to wrap a thirdparty library COM class for notifications in a C++ project

    - by geocoin
    A thirdparty vendor has provided a COM interface as an external API to their product, and for sending instructions to it, it's fine with the mechanism of generating class wrappers with visual studio by importing from the dll, then creating instances of the created classes, calling their CreateDispatch(), using the access functions and releasing when done. For return notifications, I'd normally create an EventsListener class derived from IDispatch using the Invoke function to handle events returning from the interface. This vendor has created an Events lass which I have to wrap and expose, then explicitly tell the installation where to look. all the example are given is C# where it's really easy, but I'm struggling on how to do it in C++ in the C# example, the interop dll provided is simply added as a reference and derived into a class like so: using System; using System.Runtime.InteropServices; using System.Windows.Forms; using System.Text; using <THIER INTEROP LIB> namespace some.example.namespace { [ComVisible(true)] public class EventViewer : IEvents //where IEvents is their events class { public void OnEvent(EventID EventID, object pData) //overridden function { //event handled here } } } In broad terms I assume that I must create a COM interface, since they require a ProgID from me to instantiate, but how do I derive that's been wrapped by the import and then expose the created class to COM I'm just not sure where to even start, as all the tutorials I've seen so far talk in terms of creating brand new classes not wrapping a third party one

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  • How to detect back button or forward button navigation in a silverlight navigation application

    - by parapura rajkumar
    When a Page is navigated to in silverlight you can override this method. protected override void OnNavigatedTo(NavigationEventArgs e) { base.OnNavigatedTo(e); } The NavigationEventArgs has a NavigationMode enumeration which is defined as public enum NavigationMode { New = 0, Back = 1, Forward = 2, Refresh = 3, } But calling e.NavigationMode always throws a NotImplementedException Is there a way in silverlight to detect a page is being navigated to because the user hit the forward/back browser button. What I am trying to achieve is some kind of state that can be preserved when the user hits the back button. For example assume you have a customer page which is showing a list of customers in a datagrid. The user can select a customer and there is a detail view which shows all the orders for that customer. Now within an order item you can click a hyperlink link that takes you to the shipping history of the order which is a separate page. When the user hits the back button I want to go back to the customers page and automatically select the customer he was viewing. Is this possible at all ? I also tried out the fragment navigation feature NavigationService.Navigate(new Uri("#currentcustomerid=" + customer.Id.ToString(), UriKind.Relative)); when the customer selection changes but this adds too many items to the history when the user clicks various customers on the customer page. EDIT There is also an method you can override protected override void OnNavigatingFrom(NavigatingCancelEventArgs e) { } which is the same as handling the NavigationService.Navigating event as indicated by BugFinder's answer. In this method e.NavigationMode always returns New when when you hit the Back or Forward Button. The only time this method returns Back is when you explicitly call NavigationService.GoBack()

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  • Uncatchable AccesViolationException

    - by Roy
    Hi all, I'm getting close to desperate.. I am developing a field service application for Windows Mobile 6.1 using C# and quite some p/Invoking. (I think I'm referencing about 50 native functions) On normal circumstances this goes without any problem, but when i start stressing the GC i'm getting a nasty 0xC0000005 error witch seems uncatchable. In my test i'm rapidly closing and opening a dialog form (the form did make use of native functions, but for testing i commented these out) and after a while the Windows Mobile error reporter comes around to tell me that there was an fatal error in my application. My code uses a try-catch around the Application.Run(masterForm); and hooks into the CurrentDomain.UnhandledException event, but the application still crashes. Even when i attach the debugger, visual studio just tells me "The remote connection to the device has been lost" when the exception occurs.. Since I didn't succeed to catch the exception in the managed environment, I tried to make sense out of the Error Reporter log file. But this doesn't make any sense, the only consistent this about the error is the application where it occurs in. The thread where the application occurs in is unknown to me, the module where the error occurs differs from time to time (I've seen my application.exe, WS2.dll, netcfagl3_5.dll and mscoree3_5.dll), even the error code is not always the same. (most of the time it's 0xC0000005, but i've also seen an 0X80000002 error, which is a warning accounting the first byte?) I tried debugging through bugtrap, but strangely enough this crashes with the same error code (0xC0000005). I tried to open the kdmp file with visual studio, but i can't seem to make any sense out of this because it only shows me disassembler code when i step into the error (unless i have the right .pbb files, which i don't). Same goes for WinDbg. To make a long story short: I frankly don't have a single clue where to look for this error, and I'm hoping some bright soul on stackoverflow does. I'm happy to provide some code but at this moment I don't know which piece to provide.. Any help is greatly appreciated!

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  • Implementing a State Machine in Angular.js to control routing

    - by ldn_tech_exec
    Can anyone help me with integrating a state machine to control routing? What's the best method to do this? Create a service? I need to basically intercept every $location request, run the state machine and let it figure out what the next $location.path should be. Think of the problem like a bank of questions that get added and removed over time. The user visits once in a while, passes in the user's answers object to the statemachine, and the statemachine figures out which question to load. This is my pseudocode, but i need to figure out where to put this or what event I can hook into to make sure all route requests are passed through the machine. Do I need a specific stateMachine controller? Do I create a service? Where do I use the service? Do I need to override $locationProvider? $scope.user.answers = [{ id: 32, answer: "whatever" }, { id:33, answer: "another answer" }] $scope.questions = [{ id:32, question:"what is your name?", path:"/question/1" },{ id:34, question:"how old are you?", path:"/question/2" }] var questions = $scope.questions; angular.forEach(questions, function(question) { if(question.id !exist in $scope.user.answers.id) { $location.path = question.path break; }); Thanks

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  • How to access empty ASP.NET ListView.ListViewItem to apply a style after all databinding is done?

    - by Caroline S.
    We're using a ListView with a GroupTemplate to create a three-column navigation menu with six items in each column, filling in two non-data-bound rows in the last column with an EmptyItemTemplate that contains an empty HTML list item. That part works fine, but I also need to programmatically add a CSS class to the sixth (last) item in each column. That part is also working fine for the first two columns because I'm assigning the CSS class in the DataBound event, where I can iterate through the ListView.Items collection and access the sixth item in the first two columns by using a modulus operator and counter. The problem comes in the last column, where the EmptyItemTemplate has correctly filled in two empty list items, to the last of which I also need to add this CSS class. The empty items are not included in the ListView.Items collection (that's just ListViewDataItems, and the empty items are ListViewItems). I cannot find a way to access the entire collection of ListViewItems after binding. Am I missing something? I know I can access the empty items during ItemCreated, but I can't figure out how to determine where the item I'm creating falls in the flow, and whether it's the last one. Any help would be appreciated, if this can even be done -- I'm a bit stuck.

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  • WCF Callback Faulted - what happens to the session?

    - by RemotecUk
    Just trying to get my head around what can happen when things go wrong with WCF. I have an implementation of my service contract declared with an InstanceContextMode of PerSession... [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession, ConcurrencyMode = ConcurrencyMode.Multiple)] The calls happen as follows: My client calls the server and calls GetServerUTC() to return the current UTC time of the server. This is a one way call and the server will call the client back when its ready (trivial in this instance to simply return the current time!) The server calls back to the client and for test purposes in the callback implementation on the client I throw an exception. This goes unhandled in the client (for test purposes) and the client crashes and closes down. On the server I handle the faulted event handler on the ICommunicationObject... obj.Faulted += new EventHandler(EventService_Faulted); Questions... Will this kill off the session for the current connection on the server. I presume I am free to do what I want in this method e.g. logging or something, but should I do anything specific here to terminate the session or will WCF handle this? From a best practise view point what should I do when the callback is faulted? Does it mean "something has happened in your client" and thats the end of that or is there something I a missing here? Additionally, are there any other faulted handlers I should be handling. Ive done a lot of reading on WCF and it seems sort of vague on what to do when something goes wrong. At present I am implementing a State Machine on my client which will manage the connection and determine if a user action can happen dependant on if a connection exists to the server - or is this overkill. Any tips would be really appreciated ;)

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  • How can I get jQuery validation plugin Ketchup to stop an Ajax form submission when validation fails?

    - by Marshall Sontag
    I'm using Ruby on Rails, Formtastic gem, jQuery and ketchup to validate my form. I'm submitting the form created by Formtastic inside a modal box using ajax: <% semantic_form_remote_for @contact_form, :url => '/request/contact' do |f| %> I have a validation plugin verifying the fields on the form: $(document).ready(function() { $("#new_contact_form").ketchup(); }); The problem is that semantic_form_remote_for generates an onSubmit ajax request that the jQuery validation plugins won't prevent, since it's not a normal form submission. One question on stackoverflow suggests using :condition on the remote form declaration to fire a javascript function, but I can't do that since I'm not using a function, but rather relying on a jQuery handler. I also tried putting ketchup within a submit event handler: $(document).ready(function() { $("#new_contact_form").submit(function() { $('#new_contact_form').ketchup(); }); }); No luck. Form still submits. I also tried using the beforeSend option of jQuery.ajax: $(document).ready(function() { jQuery.ajax( { beforeSend: function(){ $('#new_contact_form').ketchup(); } }); }); Validation fires off, but form is still submitted. I switched to jQuery Validation plugin just to see if it was due to some limitation in Ketchup. It turns out that Validation has a submitHandler option: $(document).ready(function() { $('#new_contact_form').validate({ submitHandler: function(form) { jQuery.ajax({ data:jQuery.param(jQuery('#new_contact_form').serializeArray()), dataType:'script', type:'post', url:'/request/contact' }); return false; } }); }); This works when I use a regular semantic_form_for instead of semantic_form_remote_for, but alas, I would rather use Ketchup. Is Ketchup just woefully lacking? Am I forced to use jQuery Validation?

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  • Adobe AIR non-Administrator application installation/upgrade on Windows

    - by bzlm
    Is there any way to allow non-Administrator users to install, upgrade or uninstall an Adobe AIR application on Windows? I've made an Adobe AIR application and packaged it as a .air package using the standard AIR mechanism for creating deployment packages. If a normal or Power user tries to install this AIR application, the Application Event Log shows an error saying administrative rights are required. And even if the user elevates during installation, administrative rights are still required for an upgrade using the automated AIR upgrade system (since an upgrade is essentially, behind the scenes, an uninstallation of a .msi package followed by an installation of another .msi package). Is there any way around this? What I've tried so far is: Using the Group Policy editor, setting Windows Installer to elevate during installations. Doesn't work, since AIR attempts a "for all users" installation. Specifying My Documents as the installation directory. Doesn't work, since AIR attempts a "for all users" installation. Giving the user Modify access to the Program Files folder where the application would usually reside. Doesn't work, since this isn't a file permissions issue. Making the user a Power User. Doesn't work, since AIR attempts a "for all users" installation. I'm guessing that both installing and upgrading would work fine for a user if the AIR installer would attempt to make an "only for me" application installation instead of a "for all users" installation, and the user was a Power User, and possibly the application was installed to My Documents I'm also guessing that this problem doesn't exist on OSX and Linux, since they have more intuitive concepts for per-user application installations.

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  • Synchronizing ASP.NET MVC action methods with ReaderWriterLockSlim

    - by James D
    Any obvious issues/problems/gotchas with synchronizing access (in an ASP.NET MVC blogging engine) to a shared object model (NHibernate, but it could be anything) at the Controller/Action level via ReaderWriterLockSlim? (Assume the object model is very large and expensive to build per-request, so we need to share it among requests.) Here's how a typical "Read Post" action would look. Enter the read lock, do some work, exit the read lock. public ActionResult ReadPost(int id) { // ReaderWriterLockSlim allows multiple concurrent writes; this method // only blocks in the unlikely event that some other client is currently // writing to the model, which would only happen if a comment were being // submitted or a new post were being saved. _lock.EnterReadLock(); try { // Access the model, fetch the post with specificied id // Pseudocode, etc. Post p = TheObjectModel.GetPostByID(id); ActionResult ar = View(p); return ar; } finally { // Under all code paths, we must release the read lock _lock.ExitReadLock(); } } Meanwhile, if a user submits a comment or an author authors a new post, they're going to need write access to the model, which is done roughly like so: [AcceptVerbs(HttpVerbs.Post)] public ActionResult SaveComment(/* some posted data */) { // try/finally omitted for brevity _lock.EnterWriteLock(); // Save the comment to the DB, update the model to include the comment, etc. _lock.ExitWriteLock(); } Of course, this could also be done by tagging those action methods with some sort of "synchronized" attribute... but however you do it, my question is is this a bad idea? ps. ReaderWriterLockSlim is optimized for multiple concurrent reads, and only blocks if the write lock is held. Since writes are so infrequent (1000s or 10,000s or 100,000s of reads for every 1 write), and since they're of such a short duration, the effect is that the model is synchronized , and almost nobody ever locks, and if they do, it's not for very long.

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  • Paging, sorting and filtering in a stored procedure (SQL Server)

    - by Fruitbat
    I was looking at different ways of writing a stored procedure to return a "page" of data. This was for use with the asp ObjectDataSource, but it could be considered a more general problem. The requirement is to return a subset of the data based on the usual paging paremeters, startPageIndex and maximumRows, but also a sortBy parameter to allow the data to be sorted. Also there are some parameters passed in to filter the data on various conditions. One common way to do this seems to be something like this: [Method 1] ;WITH stuff AS ( SELECT CASE WHEN @SortBy = 'Name' THEN ROW_NUMBER() OVER (ORDER BY Name) WHEN @SortBy = 'Name DESC' THEN ROW_NUMBER() OVER (ORDER BY Name DESC) WHEN @SortBy = ... ELSE ROW_NUMBER() OVER (ORDER BY whatever) END AS Row, ., ., ., FROM Table1 INNER JOIN Table2 ... LEFT JOIN Table3 ... WHERE ... (lots of things to check) ) SELECT * FROM stuff WHERE (Row > @startRowIndex) AND (Row <= @startRowIndex + @maximumRows OR @maximumRows <= 0) ORDER BY Row One problem with this is that it doesn't give the total count and generally we need another stored procedure for that. This second stored procedure has to replicate the parameter list and the complex WHERE clause. Not nice. One solution is to append an extra column to the final select list, (SELECT COUNT(*) FROM stuff) AS TotalRows. This gives us the total but repeats it for every row in the result set, which is not ideal. [Method 2] An interesting alternative is given here (http://www.4guysfromrolla.com/articles/032206-1.aspx) using dynamic SQL. He reckons that the performance is better because the CASE statement in the first solution drags things down. Fair enough, and this solution makes it easy to get the totalRows and slap it into an output parameter. But I hate coding dynamic SQL. All that 'bit of SQL ' + STR(@parm1) +' bit more SQL' gubbins. [Method 3] The only way I can find to get what I want, without repeating code which would have to be synchronised, and keeping things reasonably readable is to go back to the "old way" of using a table variable: DECLARE @stuff TABLE (Row INT, ...) INSERT INTO @stuff SELECT CASE WHEN @SortBy = 'Name' THEN ROW_NUMBER() OVER (ORDER BY Name) WHEN @SortBy = 'Name DESC' THEN ROW_NUMBER() OVER (ORDER BY Name DESC) WHEN @SortBy = ... ELSE ROW_NUMBER() OVER (ORDER BY whatever) END AS Row, ., ., ., FROM Table1 INNER JOIN Table2 ... LEFT JOIN Table3 ... WHERE ... (lots of things to check) SELECT * FROM stuff WHERE (Row > @startRowIndex) AND (Row <= @startRowIndex + @maximumRows OR @maximumRows <= 0) ORDER BY Row (Or a similar method using an IDENTITY column on the table variable). Here I can just add a SELECT COUNT on the table variable to get the totalRows and put it into an output parameter. I did some tests and with a fairly simple version of the query (no sortBy and no filter), method 1 seems to come up on top (almost twice as quick as the other 2). Then I decided to test probably I needed the complexity and I needed the SQL to be in stored procedures. With this I get method 1 taking nearly twice as long as the other 2 methods. Which seems strange. Is there any good reason why I shouldn't spurn CTEs and stick with method 3? UPDATE - 15 March 2012 I tried adapting Method 1 to dump the page from the CTE into a temporary table so that I could extract the TotalRows and then select just the relevant columns for the resultset. This seemed to add significantly to the time (more than I expected). I should add that I'm running this on a laptop with SQL Server Express 2008 (all that I have available) but still the comparison should be valid. I looked again at the dynamic SQL method. It turns out I wasn't really doing it properly (just concatenating strings together). I set it up as in the documentation for sp_executesql (with a parameter description string and parameter list) and it's much more readable. Also this method runs fastest in my environment. Why that should be still baffles me, but I guess the answer is hinted at in Hogan's comment.

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  • Masking FLV video in AS3 with PNG alpha channel.

    - by James Roberts
    Hey there, I'm trying to mask an FLV with a PNG alpha channel. I'm using BitmapData (from a PNG) but it's not working. Is there anything I'm missing? Cut up code below: var musclesLoader:Loader = new Loader(); var musclesContainer:Sprite = new Sprite(); var musclesImage:Bitmap = new Bitmap(); var musclesBitmapData:BitmapData; var musclesVideo:Video = new Video(752, 451.2); var connection:NetConnection = new NetConnection(); var stream:NetStream; function loadMuscles():void { musclesLoader.load(new URLRequest('img/muscles.png')); musclesLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, musclesComplete); } function musclesComplete():void { musclesBitmapData = new BitmapData(musclesLoader.content.width, musclesLoader.content.height, true, 0x000000); musclesImage.bitmapData = musclesBitmapData; musclesImage.smoothing = true; musclesContainer.addChild(musclesImage); contentContainer.addChild(musclesContainer); } function loadMusclesVideo():void { connection.connect(null); stream = new NetStream(connection); stream.client = this; musclesVideo.mask = musclesBitmapData; stage.addChild(musclesVideo); musclesVideo.attachNetStream(stream); stream.bufferTime = 1; stream.receiveAudio(true); stream.receiveVideo(true); stream.play("vid/muscles.flv"); } Outside this code I have a function that adds the containers to the stage, etc and places the objects in the appropriate spots. It sort of works - the mask applies, but in a square (the size of the boundaries of musclesBitmapData) rather than with the shape of the alpha channel. Is this the right way to go about this?

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  • Getting problem in collision detection in Java Game

    - by chetans
    Hi I am developing Spaceship Game in which i am getting problem in collision detection of moving images Game has a spaceship and number of asteroids(obstacles) i want to detect the collision between them How can i do this?`package Game; import java.applet.Applet; import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Image; import java.awt.MediaTracker; import java.awt.event.KeyEvent; import java.awt.event.KeyListener; import java.net.MalformedURLException; import java.net.URL; public class ThreadInApplet extends Applet implements KeyListener { private static final long serialVersionUID = 1L; Image[] asteroidImage; Image spaceshipImage; int[] XPosObst,YPosObst; int numberOfObstacles=0,XPosOfSpaceship,YPosOfSpaceship; int spaceButtnCntr=0,noOfObstaclesLevel=20; boolean gameStart=false,collideUp=false,collideDown=false,collideLeft=false,collideRight=false; private Image offScreenImage; private Dimension offScreenSize,d; private Graphics offScreenGraphics; int speedObstacles=1; String spaceshipImagePath="images/spaceship.png",obstacleImagepath="images/asteroid.png"; String buttonToStart="Press Space to start"; public void init() { try { asteroidImage=new Image[noOfObstaclesLevel]; XPosObst=new int[noOfObstaclesLevel]; YPosObst=new int[noOfObstaclesLevel]; XPosOfSpaceship=getWidth()/2-35; YPosOfSpaceship=getHeight()-100; spaceshipImage=getImage(new URL(getCodeBase(),spaceshipImagePath)); for(int i=0;i<noOfObstaclesLevel;i++) { asteroidImage[i]=getImage(new URL(getCodeBase(),obstacleImagepath)); XPosObst[i]=(int) (Math.random()*700); YPosObst[i]=0; } MediaTracker tracker = new MediaTracker (this); for(int i=0;i<noOfObstaclesLevel;i++) { tracker.addImage (asteroidImage[i], 0); } } catch (MalformedURLException e) { e.printStackTrace(); } setBackground(Color.black); addKeyListener(this); } public void paint(Graphics g) { g.setColor(Color.white); if(gameStart==false) { g.drawString(buttonToStart, (getWidth()/2)-60, getHeight()/2); } g.drawString("HEADfitted Solutions Pvt.Ltd.", (getWidth()/2)-80, getHeight()-20); for(int n=0;n<numberOfObstacles;n++) { if(n>0) g.drawImage(asteroidImage[n],XPosObst[n],YPosObst[n],this); } g.drawImage(spaceshipImage,XPosOfSpaceship,YPosOfSpaceship,this); } @SuppressWarnings("deprecation") public void update(Graphics g) { d = size(); if((offScreenImage == null) || (d.width != offScreenSize.width) || (d.height != offScreenSize.height)) { offScreenImage = createImage(d.width, d.height); offScreenSize = d; offScreenGraphics = offScreenImage.getGraphics(); } offScreenGraphics.clearRect(0, 0, d.width, d.height); paint(offScreenGraphics); g.drawImage(offScreenImage, 0, 0, null); } public void keyReleased(KeyEvent arg0){} public void keyTyped(KeyEvent arg0) {} Thread mainThread=new Thread() { synchronized public void run () { try { //System.out.println("in main thread"); if (gameStart==true) { moveObstacles.start(); if(collide()==false) { createObsThread.start(); } } } catch (Exception e) { e.printStackTrace(); } } }; Thread createObsThread=new Thread() { synchronized public void run () { if (spaceButtnCntr==1) { if (collide()==false) { for(int g=0;g<noOfObstaclesLevel;g++) { try { sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } numberOfObstacles++; } } } } }; Thread moveObstacles=new Thread() // Moving Obstacle images downwards after every 10 ms { synchronized public void run () { while(YPosObst[19]!=600) { if (collide()==false) { //createObsThread.start(); for(int l=0;l } repaint(); try { sleep(10); } catch (InterruptedException e) { e.printStackTrace(); } } } } }; public void keyPressed(KeyEvent e) { if(e.getKeyCode()==32) { gameStart=true; spaceButtnCntr++; if (spaceButtnCntr==1) { mainThread.start(); } } if(gameStart==true) { if(e.getKeyCode()==37 && collideLeft==false)//Spaceship movement left { new Thread () { synchronized public void run () { XPosOfSpaceship-=10; repaint(); } }.start(); } if(e.getKeyCode()==38 && collideUp==false)//Spaceship movement up { new Thread () { synchronized public void run () { YPosOfSpaceship-=10; repaint(); } }.start(); } if(e.getKeyCode()==39 && collideRight==false)//Spaceship movement right { new Thread () { synchronized public void run () { XPosOfSpaceship+=10; repaint(); } }.start(); } if(e.getKeyCode()==40 && collideDown==false)//Spaceship movement down { new Thread () { synchronized public void run () { YPosOfSpaceship+=10; repaint(); } }.start(); } } } /*public boolean collide() { int x0, y0, w0, h0, x2, y2, w2, h2; x0=XPosOfSpaceship; y0=YPosOfSpaceship; h0=spaceshipImage.getHeight(null); w0=spaceshipImage.getWidth(null); for(int i=0;i<20;i++) { x2=XPosObst[i]; y2=YPosObst[i]; h2=asteroidImage[i].getHeight(null); w2=asteroidImage[i].getWidth(null); if ((x0 > (x2 + w2)) || ((x0 + w0) < x2)) return false; System.out.println(x2+" "+y2+" "+h2+" "+w2); if ((y0 > (y2 + h2)) || ((y0 + h0) < y2)) return false; } return true; }*/ public boolean collide() { int x1,y1,x2,y2,x3,y3,x4,y4; //coordinates of obstacles int a1,b1,a2,b2,a3,b3,a4,b4; //coordinates of spaceship a1 =XPosOfSpaceship; b1=YPosOfSpaceship; a2=a1+spaceshipImage.getWidth(this); b2=b1; a3=a1; b3=b1+spaceshipImage.getHeight(this); a4=a2; b4=b3; for(int a=0;a if(x1>=a1 && x1<=a2 && x1<=b3 && x1>=b1) return (true); if(x2>=a1 && x2<=a2 && x2<=b3 && x2>=b1) return(true); //********checking asteroid touch spaceship from up direction******** if(y3==b1 && x4>=a1 && x4<=a2) { collideUp = true; return(true); } if(y3==b1 && x3>=a1 && x3<=a2) { collideUp = true; return(true); } //********checking asteroid touch spaceship from left direction****** if(x2==a1 && y4>=b1 && y4<=b3) { collideLeft=true; return(true); } if(x2==a1 && y2>=b1 && y2<=b3) { collideLeft=true; return(true); } //********checking asteroid touch spaceship from right direction***** if(x1==a2 && y3>=b2 && y3<=b4) { collideRight=true; return(true); } if(x1==a2 && y1>=b2 && y1<=b4) { collideRight=true; return(true); } //********checking asteroid touch spaceship from down direction***** if(y1==b3 && x2>=a3 && x2<=a4) { collideDown=true; return(true); } if(y1==b3 && x1>=a3 && x1<=a4) { collideDown=true; return(true); } else { collideUp=false; collideDown=false; collideLeft=false; collideRight=false; } } return(false); } } `

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  • jQuery eval of ajax inline script not throwing errors

    - by Josh
    http://stackoverflow.com/questions/606794/debugging-ajax-code-with-firebug This question is quite similar, though old and without real answers. I'm currently putting together an app that has scripts that get loaded in with an ajax request. An example: var main = _main.get(); main.load( someurl ); Where someurl is a page that contains an inline script element: <script type="text/javascript"> $(document).ready( function(){ var activities = new activities(); activities.init(); }); </script> jQuery will do a line by line eval of js that lives in inline script tags. The problem is, I get no errors or any information whatsoever in firebug when something goes awry. Does anyone have a good solution for this? Or a better practice for loading pages which contain javascript functionality? Edit: A little progress... so at the top of the page that is being loaded in via ajax, I have another script that was being included like this: <script type="text/javascript" src="javascript/pages/activities.js"></script> When I moved the inline $(document).ready() code in the page to the end of this included file, instead, syntax errors were now properly getting thrown. As an aside, I threw a console.log() into the inline script tag, and it was being logged just fine. I also tried removing the $(document).ready() altogether, and also switching it out for a $(window).load() event. No difference. May have something to do with the inline scripts dependency on the included activities.js, I guess. :: shakes head :: javascript can be a nightmare.

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  • Keeping track of leading zeros with BitSet in Java

    - by Ryan
    So, according to this question there are two ways to look at the size of a BitSet. size(), which is legacy and not really useful. I agree with this. The size is 64 after doing: BitSet b = new BitSet(8); length(), which returns the index of the highest set bit. In the above example, length() will return 0. This is somewhat useful, but doesn't accurately reflect the number of bits the BitSet is supposed to be representing in the event you have leading zeros. The information I'm dealing with rarely(if ever) falls evenly into 8-bit bytes, and the leading 0s are just as important to me as the 1s. I have some data fields that are 333 bits long, some that are 20, etc. Is there a better way to deal with bit-level details in Java that will keep track of leading zeros? Otherwise, I'm going to have to 'roll my own', so to speak. To which I have a few ideas already, but I'd prefer not to reinvent the wheel if possible.

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  • Error while rendering report(.rdl).

    - by Sushavon Banerjee
    Hi, I have generated a .rdl report file. Now, when I am going to render the .rdl report file into pdf format,exception is throwing. The exception is : - "An error occurred during local report processing." The stack trace is follows : - " at Microsoft.Reporting.WebForms.LocalReport.InternalRender(String format, Boolean allowInternalRenderers, String deviceInfo, CreateAndRegisterStream createStreamCallback, Warning[]& warnings)\r\n at Microsoft.Reporting.WebForms.LocalReport.InternalRender(String format, Boolean allowInternalRenderers, String deviceInfo, String& mimeType, String& encoding, String& fileNameExtension, String[]& streams, Warning[]& warnings)\r\n at Microsoft.Reporting.WebForms.LocalReport.Render(String format, String deviceInfo, String& mimeType, String& encoding, String& fileNameExtension, String[]& streams, Warning[]& warnings)\r\n at SaltlakeSoft.APEX2.Controllers.TestPageController.RenderReport() in E:\Documents and Settings\Administrator\Desktop\afetbuild15thmayapex2\apex2\Controllers\TestPageController.cs:line 1626\r\n at lambda_method(ExecutionScope , ControllerBase , Object[] )\r\n at System.Web.Mvc.ActionMethodDispatcher.<c_DisplayClass1.b_0(ControllerBase controller, Object[] parameters)\r\n at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)\r\n at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary2 parameters)\r\n at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary2 parameters)\r\n at System.Web.Mvc.ControllerActionInvoker.<c_DisplayClassa.b_7()\r\n at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)" My code is as follows : - LocalReport report = new LocalReport(); report.ReportPath = @"E:\Report1.rdl"; List<Employee> employeeCollection = empRepository.FindAll().ToList(); ReportDataSource reportDataSource = new ReportDataSource("dataSource1",employeeCollection); report.DataSources.Clear(); report.DataSources.Add(reportDataSource); report.Refresh(); string reportType = "PDF"; string mimeType; string encoding; string fileNameExtension; string deviceInfo ="<DeviceInfo>" +"<OutputFormat>PDF</OutputFormat>" + "<PageWidth>8.5in</PageWidth>" + "<PageHeight>11in</PageHeight>" + "<MarginTop>0.5in</MarginTop>" +"<MarginLeft>1in</MarginLeft>" + "<MarginRight>1in</MarginRight>" +"<MarginBottom>0.5in</MarginBottom>" + "</DeviceInfo>"; Warning[] warnings; string[] streams; byte[] renderedBytes; renderedBytes = report.Render(reportType,deviceInfo,out mimeType,out encoding, out fileNameExtension, out streams, out warnings); Response.Clear(); Response.ContentType = mimeType; Response.AddHeader("content-disposition", "attachment; filename=foo." + fileNameExtension); Response.BinaryWrite(renderedBytes); Response.End(); Help me please... Thanks, Sushavon

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