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• 2-column table with two foreign keys. Performance/design question.

  - by Emanuel

  Hello everyone! I recently ran into a quite complex problem and after looking around a lot I couldn't find a solution to it. I've found answers to my questions many times before on stackoverflow.com, so I decided to post here. So I'm making a user/group managment system for a web-based project, and I'm storing all related data into a postgreSQL database. This system relies on three tables: USERS GROUPS GROUP_USERS The two first tables simply define all the users and all the groups on the site, and the last table, GROUP_USERS, stores the groups every user is part of. It only has two columns: USER_ID GROUP_ID Since every user can be a member of several groups, I decided to make a separate table for this purpose, rather than storing a comma separated column in the USERS-table. Now, both columns are foreign keys, and I want to make them both primary keys as well, this since each combination of USER_ID and GROUP_ID has to be unique, and if I give them the constraint UNIQUE pgAdmin tells me that each table should have at least one Primary key. But now I am stuck with what seems to be a lot of indexes and relations to a very small table only containing numbers. In the end, I want this table to be as fast as possible, even if containing tens of thousands of rows. Size on disk shouldn't be a problem since its just all numbers anyway, but it feels quite stupid to have a full-sized index refering to a smaller table. Should I stick with my current solution, store comma-separated values in a column in the USERS-table or is there any other solution I should be aware of. PS. I don't want to use an array-column, even if they are supported by postgreSQL. I want to be as generic as possible so I can switch database later on, if necessary. EDIT: I other words, will using a compound primary key and two foreign keys in one table with only two columns have a negative impact on performance rather than the opposite due to the size of the generated index? Thank you!

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• Fastest reliable way for Clojure (Java) and Ruby apps to communicate

  - by jkndrkn

  Hi There, We have cloud-hosted (RackSpace cloud) Ruby and Java apps that will interact as follows: Ruby app sends a request to Java app. Request consists of map structure containing strings, integers, other maps, and lists (analogous to JSON). Java app analyzes data and sends reply to Ruby App. We are interested in evaluating both messaging formats (JSON, Buffer Protocols, Thrift, etc.) as well as message transmission channels/techniques (sockets, message queues, RPC, REST, SOAP, etc.) Our criteria: Short round-trip time. Low round-trip-time standard deviation. (We understand that garbage collection pauses and network usage spikes can affect this value). High availability. Scalability (we may want to have multiple instances of Ruby and Java app exchanging point-to-point messages in the future). Ease of debugging and profiling. Good documentation and community support. Bonus points for Clojure support. What combination of message format and transmission method would you recommend? Why? I've gathered here some materials we have already collected for review: Comparison of various java serialization options Comparison of Thrift and Protocol Buffers (old) Comparison of various data interchange formats Comparison of Thrift and Protocol Buffers Fallacies of Protocol Buffers RPC features Discussion of RPC in the context of AMQP (Message-Queueing) Comparison of RPC and message-passing in distributed systems (pdf) Criticism of RPC from perspective of message-passing fan Overview of Avro from Ruby programmer perspective

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• Why is there so much XML in Java these days?

  - by BD at Rivenhill

  This is really more of a philosophy/design issue. I did some work in Java back in the middle 90's and again in the early 2000's and now I'm coming back to it after spending a lot of time in C/C++ and it seems like there was an explosion of XML dependency while I was gone. Major build system tools like ant and maven depend on XML for their configuration, but I'm actually more concerned with all the frameworks, such as Spring, Hibernate, etc. My experience is that powerful supporting libraries like these are where a developer can really get leverage for building programs with lots of features without writing a lot of code, but it really seems like I'm getting one language for the price of two here. I write a bunch of Java classes, but then I also write a bunch of XML files to glue them together. The things that get done in the XML are things that I can see reasonable ways of doing in straight code without the middleman, and they don't really seem to be treated exactly like configuration files: they change rarely and they end up getting committed to source code control like the Java code itself, but they are distributed with the resulting application and need to be unpacked and installed in the classpath in order to get the application to work. I'm working with server applications that are not web-based, so maybe the domain is a bit different from what most people are doing, but I just can't help feeling that I must be doing something wrong here. Can someone point me to a good source of information for why these design choices were made and what problems they are meant to solve so that I can analyze my own experiences in this context?

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• java.lang.ClassNotFoundException: com.mysql.jdbc.Driver When run jar file

  - by user1024858

  Hi all, Connection conn = null; String url = "jdbc:mysql://localhost:3306/"; String dbName = "test"; String driver = "com.mysql.jdbc.Driver"; String userName = "root"; String password = "admin"; try { Class.forName(driver).newInstance(); conn = DriverManager.getConnection(url+dbName,userName,password); System.out.println("Connected to the database"); conn.close(); System.out.println("Disconnected from database"); } catch (Exception e) { e.printStackTrace();} I run in eclipse it's ok, but i built to jar file and run on command line java -jar Test.jar i get this error: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver at java.net.URLClassLoader$1.run(Unknown Source) at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Unknown Source) Please help me how to fix it. Thanks!!!

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• live image edit , and crop

  - by 422

  I was just thinking, which is always dangerous. We use Valums Image uploader. Aside from that, I am looking for an inline image editor, but with a difference. User uploads an image ( lets say 800 x 600 ) Our system wants to see the image ( 170 x 32 ) now I know we can use php to resize images. But I was thinking, does anyone know of a system, where we can display the image, and user can scale, and crop image ( with say a predefined overlay ) By that they scale down to nearest acceptable size, and then click crop tool, which shows a div overlay with say 70% transparency that they can drag over the image, and then click crop. So image is cropped to exact size we need, then can save . I am sure I have seen some jquery stuff done like this, just cannot for life of me find it. Essentialy, we would like to offer a simple client side image processor, thats lightweight, and then the ability to save what they did . Sorry no code to show, as its more of a request. Regards

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• How can I get a list of modified records from a SQL Server database?

  - by Pixelfish

  I am currently in the process of revamping my company's management system to run a little more lean in terms of network traffic. Right now I'm trying to figure out an effective way to query only the records that have been modified (by any user) since the last time I asked. When the application starts it loads the job information and caches it locally like the following: SELECT * FROM jobs. I am writing out the date/time a record was modified ala UPDATE jobs SET Widgets=@Widgets, LastModified=GetDate() WHERE JobID=@JobID. When any user requests the list of jobs I query all records that have been modified since the last time I requested the list like the following: SELECT * FROM jobs WHERE LastModified>=@LastRequested and store the date/time of the request to pass in as @LastRequest when the user asks again. In theory this will return only the records that have been modified since the last request. The issue I'm running into is when the user's date/time is not quite in sync with the server's date/time and also of server load when querying an un-indexed date/time column. Is there a more effective system then querying date/time information?

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• VB looping complication

  - by user1819469

  I have to come up with a program that shifts names in a text box a random amount of times. I have gotten everything up to the point where the names shifts a random amount of times. It only shifts its once, but my messagebox appears through the code as many times as the names should be shifting once i click ok. Does anyone know why the loop is not working for the name shifts. I was thinking maybe the messagebox needs to control the loop, but I have searched endlessly and cannot find how that would be done. Any suggestions or referrals to other sites would be nice thanks. My code is below. Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim RandomNumber As Integer Dim min, max As Integer Dim temp, temp2, temp3, temp4, temp5, temp6 As String Dim i As Integer min = 3 max = 11 Randomize() RandomNumber = Int((max - min + 1) * Rnd() + min) temp = n1.Text temp2 = n2.Text temp3 = n3.Text temp4 = n4.Text temp5 = n5.Text temp6 = n6.Text For i = 0 To RandomNumber - 1 n1.Text = temp6 n2.Text = temp n3.Text = temp2 n4.Text = temp3 n5.Text = temp4 n6.Text = temp5 MessageBox.Show("Shift " & i & " of " & RandomNumber & " complete") Next End Sub End Class

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• Type-safe generic data structures in plain-old C?

  - by Bradford Larsen

  I have done far more C++ programming than "plain old C" programming. One thing I sorely miss when programming in plain C is type-safe generic data structures, which are provided in C++ via templates. For sake of concreteness, consider a generic singly linked list. In C++, it is a simple matter to define your own template class, and then instantiate it for the types you need. In C, I can think of a few ways of implementing a generic singly linked list: Write the linked list type(s) and supporting procedures once, using void pointers to go around the type system. Write preprocessor macros taking the necessary type names, etc, to generate a type-specific version of the data structure and supporting procedures. Use a more sophisticated, stand-alone tool to generate the code for the types you need. I don't like option 1, as it is subverts the type system, and would likely have worse performance than a specialized type-specific implementation. Using a uniform representation of the data structure for all types, and casting to/from void pointers, so far as I can see, necessitates an indirection that would be avoided by an implementation specialized for the element type. Option 2 doesn't require any extra tools, but it feels somewhat clunky, and could give bad compiler errors when used improperly. Option 3 could give better compiler error messages than option 2, as the specialized data structure code would reside in expanded form that could be opened in an editor and inspected by the programmer (as opposed to code generated by preprocessor macros). However, this option is the most heavyweight, a sort of "poor-man's templates". I have used this approach before, using a simple sed script to specialize a "templated" version of some C code. I would like to program my future "low-level" projects in C rather than C++, but have been frightened by the thought of rewriting common data structures for each specific type. What experience do people have with this issue? Are there good libraries of generic data structures and algorithms in C that do not go with Option 1 (i.e. casting to and from void pointers, which sacrifices type safety and adds a level of indirection)?

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• Opening up process and grabbing window title. Where did I go wrong?

  - by user1632018

  In my application I allow for the users to add a program from a open file dialog, and it then adds the item to a listview and saves the items location into the tag. So what I am trying to do is when the program in the listview is selected and the button is pressed, it starts a timer and this timer checks to see if the process is running, and if it isn't launches the process, and once the process is launched it gets the window title of the process and sends it to a textbox on another form. EDIT: The question is if anyone can see why it is not working, by this I mean starting the process, then when it's started closing the form and adding the process window title to a textbox on another form. I have tried to get it working but I can't. I know that the process name it is getting is right I think my problem is to do with my for loop. Basically it isn't doing anything visible right now. I feel like I am very close with my code and im hoping it just needs a couple minor tweaks. Any help would be appreciated. Sorry if my coding practices aren't that great, im pretty new to this. EDIT:I thought I found a solution but it only works now if the process has been started already. It won't start it up. Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick Dim s As String = ListView1.SelectedItems(0).Tag Dim myFile As String = Path.GetFileName(s) Dim mu As String = myFile.Replace(".exe", "").Trim() Dim f As Process Dim p As Process() = Process.GetProcessesByName(mu) For Each f In p If p.Length > 0 Then For i As Integer = 0 To p.Length - 1 ProcessID = (p(i).Id) AutoMain.Name.Text = f.MainWindowTitle Timer1.Enabled = False Me.Close() Next Else ProcessID = 0 End If If ProcessID = 0 Then Process.Start(myFile) End If Next End Sub

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• WMI to reboot remote machine

  - by Stephen Murby

  I found this code on an old thread to shutdown the local machine: using System.Management; void Shutdown() { ManagementBaseObject mboShutdown = null; ManagementClass mcWin32 = new ManagementClass("Win32_OperatingSystem"); mcWin32.Get(); // You can't shutdown without security privileges mcWin32.Scope.Options.EnablePrivileges = true; ManagementBaseObject mboShutdownParams = mcWin32.GetMethodParameters("Win32Shutdown"); // Flag 1 means we want to shut down the system. Use "2" to reboot. mboShutdownParams["Flags"] = "1"; mboShutdownParams["Reserved"] = "0"; foreach (ManagementObject manObj in mcWin32.GetInstances()) { mboShutdown = manObj.InvokeMethod("Win32Shutdown", mboShutdownParams, null); } } Is it possible to use a similar WMI method to reboot flag"2" a remote machine, for which i only have machine name, not IPaddress. EDIT: I currently have; SearchResultCollection allMachinesCollected = machineSearch.FindAll(); Methods myMethods = new Methods(); string pcName; ArrayList allComputers = new ArrayList(); foreach (SearchResult oneMachine in allMachinesCollected) { //pcName = oneMachine.Properties.PropertyNames.ToString(); pcName = oneMachine.Properties["name"][0].ToString(); allComputers.Add(pcName); MessageBox.Show(pcName + "has been sent the restart command."); Process.Start("shutdown.exe", "-r -f -t 0 -m \" + pcName); } but this doesn't work, and i would prefer WMI going forward.

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• Java JRE vs GCJ

  - by Martijn Courteaux

  Hi, I have this results from a speed test I wrote in Java: Java real 0m20.626s user 0m20.257s sys 0m0.244s GCJ real 3m10.567s user 3m5.168s sys 0m0.676s So, what is the but of GCJ then? With this results I'm sure I'm not going to compile it with GCJ! I tested this on Linux, are the results in Windows maybe better than that? This was the code from the application: public static void main(String[] args) { String str = ""; System.out.println("Start!!!"); for (long i = 0; i < 5000000L; i++) { Math.sqrt((double) i); Math.pow((double) i, 2.56); long j = i * 745L; String string = new String(String.valueOf(i)); string = string.concat(" kaka pipi"); // "Kaka pipi" is a kind of childly call in Dutch. string = new String(string.toUpperCase()); if (i % 300 == 0) { str = ""; } else { str += Long.toHexString(i); } } System.out.println("Stop!!!"); }

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• Getting information from servlet created html

  - by user541597

  I have a servlet that creates an html text box and then redirects to another servlet on submit. How can I access the value of the html text box from the new servlet? I am able to access servlet variables from the new servlet but I am not aware of how to access the value of the html generated code. thanks, Here is the servlet that gets the text input public class ServletB extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { response.setContentType("text/html"); String value = System.getProperty("card"); PrintWriter out = response.getWriter(); out.println("<center><h1>Your preffered method of payment is "+value+"</h1><br />"); out.println("Please Enter Card Number<input type =\"text\" name = \"number\"/><form action=\"http://codd.cs.gsu.edu:9999/cpereyra183/servlet/ServletC\"><input type =\"submit\" value=\"Continue\" /><input type=\"button\" value=\"Cancel\" /></center>"); } }} This is the servlet the first servlet redirects to all I do is try to do is output the text input public class ServletC extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { response.setContentType("text/html"); String value = System.getProperty("card"); PrintWriter out = response.getWriter(); out.println(request.getParameter("number")); } }

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• Speed up csv export when using php from mysql database query

  - by John

  Ok, so i've got a web system (built on codeigniter & running on mysql) that allows people to query a database of postal address data by making selections in a series of forms until they arrive at the selection that want, pretty standard stuff. They can then buy that information and download it via that system. The queries run very fast, but when it comes to applying that query to the database,and exporting it to csv, once the datasets get to around the 30,000 record mark (each row has around 40 columns of which about 20 are all populated with on average 20 chars of data per cell) it can take 5 or so minutes to export to csv. So, my question is, what is the main cause for the slowness? Is it that the resultset of data from the query is so large, that it is running into memory issues? Therefore should i allow much more memory to the process? Or, is there a much more efficient way of exporting to csv from a mysql query that i'm not doing? Should i save the contents of the query to a temp table and simply export the temp table to csv? Or am i going about this all wrong? Also, is the fact that i'm using Codeigniters Active Record for this prohibitive due to the way that it stores the resultset? Any advice is welcome! Thank you for reading!

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• Optimize Duplicate Detection

  - by Dave Jarvis

  Background This is an optimization problem. Oracle Forms XML files have elements such as: <Trigger TriggerName="name" TriggerText="SELECT * FROM DUAL" ... /> Where the TriggerText is arbitrary SQL code. Each SQL statement has been extracted into uniquely named files such as: sql/module=DIAL_ACCESS+trigger=KEY-LISTVAL+filename=d_access.fmb.sql sql/module=REP_PAT_SEEN+trigger=KEY-LISTVAL+filename=rep_pat_seen.fmb.sql I wrote a script to generate a list of exact duplicates using a brute force approach. Problem There are 37,497 files to compare against each other; it takes 8 minutes to compare one file against all the others. Logically, if A = B and A = C, then there is no need to check if B = C. So the problem is: how do you eliminate the redundant comparisons? The script will complete in approximately 208 days. Script Source Code The comparison script is as follows: #!/bin/bash echo Loading directory ... for i in $(find sql/ -type f -name \*.sql); do echo Comparing $i ... for j in $(find sql/ -type f -name \*.sql); do if [ "$i" = "$j" ]; then continue; fi # Case insensitive compare, ignore spaces diff -IEbwBaq $i $j > /dev/null # 0 = no difference (i.e., duplicate code) if [ $? = 0 ]; then echo $i :: $j >> clones.txt fi done done Question How would you optimize the script so that checking for cloned code is a few orders of magnitude faster? System Constraints Using a quad-core CPU with an SSD; trying to avoid using cloud services if possible. The system is a Windows-based machine with Cygwin installed -- algorithms or solutions in other languages are welcome. Thank you!

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• Can't declare an abstract method private....

  - by Zombies

  I want to do this, yet I can't. Here is my scenario and rational. I have an abstract class for test cases that has an abstract method called test(). The test() method is to be defined by the subclass; it is to be implemented with logic for a certain application, such as CRMAppTestCase extends CompanyTestCase. I don't want the test() method to be invoked directly, I want the super class to call the test() method while the sub class can call a method which calls this (and does other work too, such as setting a current date-time right before the test is executed for example). Example code: public abstract class CompanyTestCase { //I wish this would compile, but it cannot be declared private private abstract void test(); public TestCaseResult performTest() { //do some work which must be done and should be invoked whenever //this method is called (it would be improper to expect the caller // to perform initialization) TestCaseResult result = new TestCaseResult(); result.setBeginTime(new Date()); long time = System.currentTimeMillis(); test(); //invoke test logic result.setDuration(System.currentTimeMillis() - time); return result; } } Then to extend this.... public class CRMAppTestCase extends CompanyTestCase { public void test() { //test logic here } } Then to call it.... TestCaseResult result = new CRMAppTestCase().performTest();

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• What is the Rule of Thumb on Exposing Encapsulated Class Methods

  - by javamonkey79

  Consider the following analogy: If we have a class: "Car" we might expect it to have an instance of "Engine" in it. As in: "The car HAS-A engine". Similarly, in the "Engine" class we would expect an instance of "Starting System" or "Cooling System" which each have their appropriate sub-components. By the nature of encapsulation, is it not true that the car "HAS-A" "radiator hose" in it as well as the engine? Therefore, is it appropriate OO to do something like this: public class Car { private Engine _engine; public Engine getEngine() { return _engine; } // is it ok to use 'convenience' methods of inner classes? // are the following 2 methods "wrong" from an OO point of view? public RadiatorHose getRadiatorHose() { return getCoolingSystem().getRadiatorHose(); } public CoolingSystem getCoolingSystem() { return _engine.getCoolingSystem(); } } public class Engine { private CoolingSystem _coolingSystem; public CoolingSystem getCoolingSystem() { return _coolingSystem; } } public class CoolingSystem { private RadiatorHose _radiatorHose; public RadiatorHose getRadiatorHose() { return _radiatorHose; } } public class RadiatorHose {//... }

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• Criteria for triggering garbage collection in .Net

  - by Kennet Belenky

  I've come across some curious behavior with regard to garbage collection in .Net. The following program will throw an OutOfMemoryException very quickly (after less than a second on a 32-bit, 2GB machine). The Foo finalizer is never called. class Foo { static Dictionary<Guid, WeakReference> allFoos = new Dictionary<Guid, WeakReference>(); Guid guid = Guid.NewGuid(); byte[] buffer = new byte[1000000]; static Random rand = new Random(); public Foo() { // Uncomment the following line and the program will run forever. // rand.NextBytes(buffer); allFoos[guid] = new WeakReference(this); } ~Foo() { allFoos.Remove(guid); } static public void Main(string args[]) { for (; ; ) { new Foo(); } } } If the rand.nextBytes line is uncommented, it will run ad infinitum, and the Foo finalizer is regularly invoked. Why is that? My best guess is that in the former case, either the CLR or the Windows VMM is lazy about allocating physical memory. The buffer never gets written to, so the physical memory is never used. When the address space runs out, the system crashes. In the latter case, the system runs out of physical memory before it runs out of address space, the GC is triggered and the objects are collected. However, here's the part I don't get. Assuming my theory is correct, why doesn't the GC trigger when the address space runs low? If my theory is incorrect, then what's the real explanation?

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• Hibernate not loading associated object

  - by Noor

  Hi, i am trying to load a hibernate object ForumMessage but in it contain another object Users and the Users object is not being loaded. My ForumMessage Mapping File: <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated Jan 4, 2011 10:10:29 AM by Hibernate Tools 3.4.0.Beta1 --> <hibernate-mapping> <class name="com.BiddingSystem.Models.ForumMessage" table="FORUMMESSAGE"> <id name="ForumMessageId" type="long"> <column name="FORUMMESSAGEID" /> <generator class="native" /> </id> <property name="ForumMessage" type="java.lang.String"> <column name="FORUMMESSAGE" /> </property> <many-to-one name="User" class="com.BiddingSystem.Models.Users" fetch="join"> <column name="UserId" /> </many-to-one> <property name="DatePosted" type="java.util.Date"> <column name="DATEPOSTED" /> </property> <many-to-one name="Topic" class="com.BiddingSystem.Models.ForumTopic" fetch="join"> <column name="TopicId" /> </many-to-one> </class> </hibernate-mapping> and I am using the follwing code: Session session = gileadHibernateUtil.getSessionFactory().openSession(); SQL="from ForumMessage"; System.out.println(SQL); Query query=session.createQuery(SQL); System.out.println(query.list().size()); return new LinkedList <ForumMessage>(query.list());

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• Why does the BackgroundWorker in WPF need Thread.Sleep to update UI controls?

  - by user364060

  namespace WpfApplication1 { /// <summary> /// Interaction logic for Window1.xaml /// </summary> public partial class Window1 : Window { BackgroundWorker bgWorker; Action<int> myProgressReporter; public Window1() { InitializeComponent(); bgWorker = new BackgroundWorker(); bgWorker.DoWork += bgWorker_Task; bgWorker.RunWorkerCompleted += myWorker_RunWorkerCompleted; // hook event to method bgWorker.ProgressChanged += bgWorker_ReportProgress; // hook the delegate to the method myProgressReporter = updateProgress; bgWorker.WorkerReportsProgress = true; } private void myWorker_RunWorkerCompleted(object sender, System.ComponentModel.RunWorkerCompletedEventArgs e) { object result; result = e.Result; MessageBox.Show(result.ToString()); progressBar1.Value = 0; button1.IsEnabled = true; } private void bgWorker_ReportProgress(object sender, ProgressChangedEventArgs e) { System.Windows.Threading.Dispatcher disp = button1.Dispatcher; disp.BeginInvoke(myProgressReporter,e.ProgressPercentage); //Dispatcher.BeginInvoke(myProgressReporter, DispatcherPriority.Normal, e.ProgressPercentage); } private void updateProgress(int progressPercentage) { progressBar1.Value = progressPercentage; } private void bgWorker_Task(Object sender, DoWorkEventArgs e) { int total = 1000; for (int i = 1; i <= total; i++) { if (bgWorker.WorkerReportsProgress) { int p = (int)(((float)i / (float)total) * 100); bgWorker.ReportProgress(p); } Thread.Sleep(1); // Without Thread.Sleep(x) the main thread freezes or gives stackoverflow exception, } e.Result = "Completed"; } private void button1_Click(object sender, RoutedEventArgs e) { if(!bgWorker.IsBusy) bgWorker.RunWorkerAsync("This is a background process"); button1.IsEnabled = false; } } }

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• Responsive: two different toggles on same element

  - by Mathijs Delva

  I'm having difficulties with the following problem. For a responsive website, i need to use the same toggle element for both a toggle system for one window width, and another toggle system for a second window width. I have the following snippets: 1.A simple hover for a language dropdown, which should be executed for resolutions greater than 980px. $('#clickme').hover(function() { $(this).parent().find("#select-language").show(); $(this).find("> a span").css({"opacity":"0.5"}); }, function() { $(this).parent().find("#select-language").hide(); $(this).find("> a span").css({"opacity":"1"}); }); 2.A simple click for the same language toggle, which should be executed for resolutions smaller than 980px. jQuery('#clickme').click(function() { jQuery("#select-language-mobile").slideToggle("fast"); }); I need to nest these two, so that when the user is viewing the website in one resolution, the click function with be fired, and in the other case the hover function. Can anybody help me with this? PS: I'm sorry, but the code blocks don't seem to work at the moment.

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• How to construct objects based on XML code?

  - by the_drow

  I have XML files that are representation of a portion of HTML code. Those XML files also have widget declarations. Example XML file: <message id="msg"> <p> <Widget name="foo" type="SomeComplexWidget" attribute="value"> inner text here, sets another attribute or inserts another widget to the tree if needed... </Widget> </p> </message> I have a main Widget class that all of my widgets inherit from. The question is how would I create it? Here are my options: Create a compile time tool that will parse the XML file and create the necessary code to bind the widgets to the needed objects. Advantages: No extra run-time overhead induced to the system. It's easy to bind setters. Disadvantages: Adds another step to the build chain. Hard to maintain as every widget in the system should be added to the parser. Use of macros to bind the widgets. Complex code Find a method to register all widgets into a factory automatically. Advantages: All of the binding is done completely automatically. Easier to maintain then option 1 as every new widget will only need to call a WidgetFactory method that registers it. Disadvantages: No idea how to bind setters without introducing a maintainability nightmare. Adds memory and run-time overhead. Complex code What do you think is better? Can you guys suggest a better solution?

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• Labview + National Instruments hardware or ???

  - by NSL

  I'm in the processes of buying a new data acquisition system for my company to use for various projects. At first, it's primary purpose will be to monitor up to 20 thermocouples and control the temperature of a composites oven. However, I also plan on using it to monitor accelerometers, strain gauges, and to act as a signal generator. I probably won't be the only one to use it, but I have a good bit of programming experience with Atmel microcontrollers (C). I've used Labview before, but ~5 years ago. Labview would be good because it is easy to pick up on for both me and my coworkers. On the flip side, it's expensive. Right now I have a NI CompactDAQ system with 2 voltage and one thermocouple cards + Labview speced out and it's going to cost $5779! I'm going to try to get the same I/O capabilities with different NI hardware for less $ + labview to see if I can get it for less $. I'd like to see if anyone has any suggestions other than Labview for me. Thanks in advance!

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• Page Entirely Blank Despite Having Source Code! (TinyMCE, FireFox)

  - by Chris Cooper

  Alright guys, here's a tough one... In reference to this page. The page will seemingly randomly not display the output of server when using Firefox (version 3.5). I have not seen this problem occur in Safari or IE. The best way to have the problem occur is just reload the page about 10 times and it ought to have happened by then, and once it does - it'll continue on subsequent refreshes until you change the page. The problem is literally the browser not displaying the output (code). Viewing the source shows all the appropriate code yet the browser displays a blank white page. The web developer and firebug plugins don't show any errors that would indicate the problem. I have tested this on a separate system and OS and it occurs in Firefox on that system as well. The problem did not occur until after TinyMCE (A Rich Text Editor JavaScript library for textareas) was added to the project. TinyMCE works however, where it should. I know this is a confusing problem, but I am completely lost as to what could be causing this significant issue. Thanks in advance. EDIT: If it's any help... I've noticed that if I cause a css file error by changing a stylesheet source to something non-existant (xxx.css), the page will continuously display without a problem (besides whatever related css not showing due to the src change). I've also noticed that causing any simple javascript error with some bad code will cause the page to load properly continuously (besides of course javascript not running on the page). EDIT#2: Moving all <script> tags down at the tail of the <body> 'fixes' (well, hides) this error and the page shows normally. A band-aid.

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• What's the deal with the hidden Throw when catching a ThreadAbortException?

  - by priehl

  I'm going through a book of general c# development, and I've come to the thread abort section. The book says something along the lines that when you call Thread.Abort() on another thread, that thread will throw a ThreadAbortException, and even if you tried to supress it it would automatically rethrow it, unless you did some bs that's generally frowned upon. Here's the simple example offered. using System; using System.Threading; public class EntryPoint { private static void ThreadFunc() { ulong counter = 0; while (true) { try { Console.WriteLine("{0}", counter++); } catch (ThreadAbortException) { // Attempt to swallow the exception and continue. Console.WriteLine("Abort!"); } } } static void Main() { try { Thread newThread = new Thread(new ThreadStart(EntryPoint.ThreadFunc)); newThread.Start(); Thread.Sleep(2000); // Abort the thread. newThread.Abort(); // Wait for thread to finish. newThread.Join(); } catch (Exception e) { Console.WriteLine(e.ToString()); } } } The book says: When your thread finishes processing the abort exception, the runtime implicitly rethrows it at the end of your exception handler. It’s the same as if you had rethrown the exception yourself. Therefore, any outer exception handlers or finally blocks will still execute normally. In the example, the call to Join won’t be waiting forever as initially expected. So i wrapped a try catch around the Thread.Abort() call and set a break point, expecting it to hit this, considering the text says "any outer exception handlers or finally blocks will still execute normally". BUT IT DOES NOT. I'm racking my brain to figure out why. Anyone have any thoughts on why this isn't the case? Is the book wrong? Thanks in advance.

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• Error In VB.Net code

  - by Michael

  I am getting the error "Format Exception was unhandled at "Do While objectReader.Peek < -1 " and after. any help would be wonderful. 'Date: Class 03/20/2010 'Program Purpose: When code is executed data will be pulled from a text file 'that contains the named storms to find the average number of storms during the time 'period chosen by the user and to find the most active year. between the range of 'years 1990 and 2008 Option Strict On Public Class frmHurricane Private _intNumberOfHuricanes As Integer = 5 Public Shared _intSizeOfArray As Integer = 7 Public Shared _strHuricaneList(_intSizeOfArray) As String Private _strID(_intSizeOfArray) As String Private _decYears(_intSizeOfArray) As Decimal Private _decFinal(_intSizeOfArray) As Decimal Private _intNumber(_intSizeOfArray) As Integer Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 'The frmHurricane load event reads the Hurricane text file and 'fill the combotBox object with the data. 'Initialize an instance of the StreamReader Object and declare variable page 675 on the book Dim objectReader As IO.StreamReader Dim strLocationAndNameOfFile As String = "C:\huricanes.txt" Dim intCount As Integer = 0 Dim intFill As Integer Dim strFileError As String = "The file is not available. Please restart application when available" 'This is where we code the file if it exist. If IO.File.Exists(strLocationAndNameOfFile) Then objectReader = IO.File.OpenText(strLocationAndNameOfFile) 'Read the file line by line until the file is complete Do While objectReader.Peek <> -1 **_strHuricaneList(intCount) = objectReader.ReadLine() _strID(intCount) = objectReader.ReadLine() _decYears(intCount) = Convert.ToDecimal(objectReader.ReadLine()) _intNumber(intCount) = Convert.ToInt32(objectReader.ReadLine()) intCount += 1** Loop objectReader.Close() 'With any luck the data will go to the Data Box For intFill = 0 To (_strID.Length - 1) Me.cboByYear.Items.Add(_strID(intFill)) Next Else MsgBox(strFileError, , "Error") Me.Close() End If End Sub

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