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  • Add collection or array to wpf resource dictionary

    - by Chris Cap
    I've search high and low and can't find an answer to this. I have two questions How do you create an array or collection in XAML. I've got an array I want to stick in there and bind to a combo box. My first idea was to put an ItemsControl in a resource dictionary, but the ItemsSource of a combo box expects IEnumerable so that didn't work. Here's what I've tried in my resource dictionary and neither works <ItemsControl x:Key="stateList"> <sys:String>AL</sys:String> <sys:String>CA</sys:String> <sys:String>CN</sys:String> </ItemsControl> <ItemsControl x:Key="stateList2"> <ComboBoxItem>AL</ComboBoxItem> <ComboBoxItem>CA</ComboBoxItem> <ComboBoxItem>CN</ComboBoxItem> </ItemsControl> and here's how I bind to it <ComboBox SelectedValue="{Binding Path=State}" ItemsSource="{Binding Source={StaticResource stateList2}}" > </ComboBox> EDIT: UPDATED I got this first part to work this way <col:ArrayList x:Key="stateList3"> <sys:String>AL</sys:String> <sys:String>CA</sys:String> <sys:String>CN</sys:String> </col:ArrayList> However, I'd rather not use an array list, I'd like to use a generic list so if anyone knows how please let me know. EDIT UPDATE: I guess XAML has very limited support for generics so maybe an array list is the best I can do for now, but I would still like help on the second question if anyone has an anser 2nd. I've tried referencing a merged resource dictionary in my XAML and had problems because under Window.resources I had more than just the dictionary so it required me to add x:Key. Once I add the key, the system can no longer find the items in my resource dictionary. I had to move the merged dictionary to Grid.Resources instead. Ideally I'd like to reference the merged dictionary in the app.xaml but I have the same problem Here's some sample code. This first part required an x:key to compile because I have converter and it complained that every item must have a key if there is more than one <UserControl.Resources> <win:BooleanToVisibilityConverter x:Key="VisibilityConverter" /> <ResourceDictionary> <ResourceDictionary.MergedDictionaries> <ResourceDictionary Source="/ResourcesD.xaml" /> </ResourceDictionary.MergedDictionaries> </ResourceDictionary> </UserControl.Resources> I had to change it to this <UI:BaseStep.Resources> <win:BooleanToVisibilityConverter x:Key="VisibilityConverter" /> </UI:BaseStep.Resources> <Grid> <Grid.Resources> <ResourceDictionary> <ResourceDictionary.MergedDictionaries> <ResourceDictionary Source="/ResourcesD.xaml" /> </ResourceDictionary.MergedDictionaries> </ResourceDictionary> </Grid.Resources> </Grid> Thank you

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  • WPF MenuItem.Command binding to ElementName results to System.Windows.Data Error: 4 : Cannot find so

    - by e28Makaveli
    I have the following XAML: <UserControl x:Class="EMS.Controls.Dictionary.TOCControl" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:vm="clr-namespace:EMS.Controls.Dictionary.Models" xmlns:diagnostics="clr-namespace:System.Diagnostics;assembly=WindowsBase" x:Name="root" > <TreeView x:Name="TOCTreeView" Background="White" Padding="3,5" ContextMenuOpening="TOCTreeView_ContextMenuOpening" ItemsSource="{Binding Children}" BorderBrush="{x:Null}" > <TreeView.ItemTemplate> <HierarchicalDataTemplate ItemsSource="{Binding Path=Children, Mode=OneTime}"> <Grid > <Grid.ColumnDefinitions> <ColumnDefinition Width="Auto"/> <!--<ColumnDefinition Width="Auto"/>--> <ColumnDefinition Width="*"/> </Grid.ColumnDefinitions> <!--<CheckBox VerticalAlignment="Center" IsChecked="{Binding IsVisible}"/>--> <ContentPresenter Grid.Column="0" Height="16" Width="20" Content="{Binding LayerRepresentation}" /> <!--<ContentPresenter Grid.Column="1" > <ContentPresenter.Content> Test </ContentPresenter.Content> </ContentPresenter>--> <TextBlock Grid.Column="2" FontWeight="Normal" Text="{Binding Path=Alias, Mode=OneWay}" > <ToolTipService.ToolTip> <TextBlock Text="{Binding Description}" TextWrapping="Wrap"/> </ToolTipService.ToolTip> </TextBlock> </Grid> <HierarchicalDataTemplate.ItemTemplate> <HierarchicalDataTemplate ItemsSource="{Binding Path=Children, Mode=OneTime}"> <!--<DataTemplate>--> <Grid > <Grid.ColumnDefinitions> <ColumnDefinition Width="Auto"/> <ColumnDefinition Width="Auto"/> <ColumnDefinition Width="*"/> </Grid.ColumnDefinitions> <CheckBox VerticalAlignment="Center" IsChecked="{Binding IsVisible}"/> <ContentPresenter Grid.Column="1" Content="{Binding LayerRepresentation, Mode=OneWay}" /> <TextBlock Margin="0,1,0,1" Text="{Binding Path=Alias, Mode=OneWay}" Grid.Column="2"> <ToolTipService.ToolTip> <TextBlock Text="{Binding Description}" TextWrapping="Wrap"/> </ToolTipService.ToolTip> </TextBlock> </Grid> <!--</DataTemplate>--> </HierarchicalDataTemplate> </HierarchicalDataTemplate.ItemTemplate> </HierarchicalDataTemplate> </TreeView.ItemTemplate> <TreeView.ContextMenu> <ContextMenu> <MenuItem Name="miRemove" Header="Remove" Command="{Binding ElementName=root, Path=RemoveItemCmd, diagnostics:PresentationTraceSources.TraceLevel=High}"> <MenuItem.Icon> <Image Source="../images/16x16/Delete.png"/> </MenuItem.Icon> </MenuItem> <MenuItem Header="Properties" Command="{Binding ElementName=root, Path=GetItemPropertiesCmd}"/> </ContextMenu> </TreeView.ContextMenu> </TreeView> </UserControl> Code behind for this UserControl has two ICommand properties with names: RemoveItemCmd and GetItemPropertiesCmd. However, I get System.Windows.Data Error: 4 : Cannot find source for binding with reference 'ElementName=root'. BindingExpression:Path=RemoveItemCmd; DataItem=null; target element is 'MenuItem' (Name='miRemove'); target property is 'Command' (type 'ICommand') System.Windows.Data Error: 4 : Cannot find source for binding with reference 'ElementName=root'. BindingExpression:Path=GetItemPropertiesCmd; DataItem=null; target element is 'MenuItem' (Name=''); target property is 'Command' (type 'ICommand') when UserControl is constructed. Why is this and how do I resolve?

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  • Animating the offset of the scrollView in a UICollectionView/UITableView causes prematurely disappearing cells

    - by radutzan
    We have a UICollectionView with a custom layout very similar to UITableView (it scrolls vertically). The UICollectionView displays only 3 cells simultaneously, with one of them being the currently active cell: [ 1 ] [*2*] [ 3 ] (The active cell here is #2.) The cells are roughly 280 points high, so only the active cell is fully visible on the screen. The user doesn't directly scroll the view to navigate, instead, she swipes the active cell horizontally to advance to the next cell. We then do some fancy animations and scroll the UICollectionView so the next cell is in the "active" position, thus making it the active one, moving the old one away and bringing up the next cell in the queue: [ 2 ] [*3*] [ 4 ] The problem here is setting the UICollectionView's offset. We currently set it in a UIView animation block (self.collectionView.contentOffset = targetOffset;) along with three other animating properties, which mostly works great, but causes the first cell (the previously active one, in the latter case, #2) to vanish as soon as the animation starts running, even before the delay interval completes. This is definitely not ideal. I've thought of some solutions, but can't figure out the best one: Absurdly enlarge the UICollectionView's frame to fit five cells instead of three, thus forcing it to keep the cells in memory even if they are offscreen. I've tried this and it works, but it sounds like an awfully dirty hack. Take a snapshot of the rendered content of the vanishing cell, put it in a UIImageView, add the UIImageView as a subview of the scrollView just before the cell goes away in the exact same position of the old cell, removing it once the animation ends. Sounds less sucky than the previous option (memory-wise, at least), but still kinda hacky. I also don't know the best way to accomplish this, please point me in the right direction. Switch to UIScrollView's setContentOffset:animated:. We actually used to have this, and it fixed the disappearing cell issue, but running this in parallel with the other UIView animations apparently competes for the attention of the main thread, thus creating a terribly choppy animation on single-core devices (iPhone 3GS/4). It also doesn't allow us to change the duration or easing of the animation, so it feels out of sync with the rest. Still an option if we can find a way to make it work in harmony with the UIView block animations. Switch to UICollectionView's scrollToItemAtIndexPath:atScrollPosition:animated:. Haven't tried this, but it has a big downside: it only takes 3 possible constants (that apply to this case, at least) for the target scroll position: UICollectionViewScrollPositionTop, UICollectionViewScrollPositionCenteredVertically and UICollectionViewScrollPositionBottom. The active cell could vary its height, but it always has to be 35 points from the top of the window, and these options don't provide enough control to accomplish the design. It could also potentially be just as problematic as 3.1. Still an option because there might be a way to go around the scroll position thing that I don't know of, and it might not have the same issue with the main thread, which seems unlikely. Any help will be greatly appreciated. Please ask if you need clarification. Thanks a lot!

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  • Paying great programmers more than average programmers

    - by Kelly French
    It's fairly well recognized that some programmers are up to 10 times more productive than others. Joel mentions this topic on his blog. There is a whole blog devoted to the idea of the "10x productive programmer". In years since the original study, the general finding that "There are order-of-magnitude differences among programmers" has been confirmed by many other studies of professional programmers (Curtis 1981, Mills 1983, DeMarco and Lister 1985, Curtis et al. 1986, Card 1987, Boehm and Papaccio 1988, Valett and McGarry 1989, Boehm et al 2000). Fred Brooks mentions the wide range in the quality of designers in his "No Silver Bullet" article, The differences are not minor--they are rather like the differences between Salieri and Mozart. Study after study shows that the very best designers produce structures that are faster, smaller, simpler, cleaner, and produced with less effort. The differences between the great and the average approach an order of magnitude. The study that Brooks cites is: H. Sackman, W.J. Erikson, and E.E. Grant, "Exploratory Experimental Studies Comparing Online and Offline Programming Performance," Communications of the ACM, Vol. 11, No. 1 (January 1968), pp. 3-11. The way programmers are paid by employers these days makes it almost impossible to pay the great programmers a large multiple of what the entry-level salary is. When the starting salary for a just-graduated entry-level programmer, we'll call him Asok (From Dilbert), is $40K, even if the top programmer, we'll call him Linus, makes $120K that is only a multiple of 3. I'd be willing to be that Linus does much more than 3 times what Asok does, so why wouldn't we expect him to get paid more as well? Here is a quote from Stroustrup: "The companies are complaining because they are hurting. They can't produce quality products as cheaply, as reliably, and as quickly as they would like. They correctly see a shortage of good developers as a part of the problem. What they generally don't see is that inserting a good developer into a culture designed to constrain semi-skilled programmers from doing harm is pointless because the rules/culture will constrain the new developer from doing anything significantly new and better." This leads to two questions. I'm excluding self-employed programmers and contractors. If you disagree that's fine but please include your rationale. It might be that the self-employed or contract programmers are where you find the top-10 earners, but please provide a explanation/story/rationale along with any anecdotes. [EDIT] I thought up some other areas in which talent/ability affects pay. Financial traders (commodities, stock, derivatives, etc.) designers (fashion, interior decorators, architects, etc.) professionals (doctor, lawyer, accountant, etc.) sales Questions: Why aren't the top 1% of programmers paid like A-list movie stars? What would the industry be like if we did pay the "Smart and gets things done" programmers 6, 8, or 10 times what an intern makes? [Footnote: I posted this question after submitting it to the Stackoverflow podcast. It was included in episode 77 and I've written more about it as a Codewright's Tale post 'Of Rockstars and Bricklayers'] Epilogue: It's probably unfair to exclude contractors and the self-employed. One aspect of the highest earners in other fields is that they are free-agents. The competition for their skills is what drives up their earning power. This means they can not be interchangeable or otherwise treated as a plug-and-play resource. I liked the example in one answer of a major league baseball team trying to field two first-basemen. Also, something that Joel mentioned in the Stackoverflow podcast (#77). There are natural dynamics to shrink any extreme performance/pay ranges between the highs and lows. One is the peer pressure of organizations to pay within a given range, another is the likelyhood that the high performer will realize their undercompensation and seek greener pastures.

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  • Getting this CSS to work in IE6

    - by jerrygarciuh
    Hi folks, Working on this page: http://www.karlsenner.dreamhosters.com/about.php and having trouble with the navigation in IE6. It validates as XHTML 1.0 Transitional. Works great in FF, IE 8, Chrome, and Windows Safari. In IE6 and Opera 10 the drop menus appear too high. I tried adding in the different versions of http://code.google.com/p/ie7-js/ but it did not solve the issue in IE. The CSS looks like this: #wrapper { position: relative; display: block; background-color: inherit; margin: 0px auto; padding: 0; width: 900px; min-height: 900px; } #nav {} .navImage { position:relative; display:inline; height:102px; /* added in hopes of helping IE position but no dice */ } .subMenu { position:absolute; z-index:10; background-color:#FFF; top: 14px; left:0; } .subMenu a:link, .subMenu a:visited, .subMenu a:active{ display:block; width:90%; padding:6px; margin:0; color:#3CF; font-family:Tahoma, Geneva, sans-serif; font-size:14px; text-decoration:none; font-weight:bold; } .subMenu a:hover{ display:block; width:90%; padding:6px; margin:0; color:#3CF; background-color:#CCC; font-family:Tahoma, Geneva, sans-serif; font-size:14px; text-decoration:none; font-weight:bold; } jQuery rollovers: $('#navcompany').hover(function () { $('#companyMenu').css('display', 'block'); $('#companyImg').attr('src','g/nav/company_over.gif'); }, function () { $('#companyMenu').css('display', 'none'); $('#companyImg').attr('src','g/nav/company.gif'); }); And one of the cells. Since the menu is coming out of PHP and IE was not respecting the widths I just use PHP to get the nav image widths and write them to styles on the fly. Solved the width issue as IE acted like they should inherit their width from the wrapper. This may be a clue as to why they don't appear below their nav images but I can't sort it. <div id="navcompany" class="navImage" style="width:128px"> <a href="about.php"> <img src="g/nav/company_over.gif" name="companyImg" width="128" height="102" border="0" id="companyImg" alt="company" /> </a> <div id="companyMenu" class="subMenu" style="display:none; width:128px"> <a href="about.php">About us</a> <a href="location.php">Our location</a> </div> </div> Any advice greatly appreciated! JG

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  • IE6 iframe anchor links moves iframe up

    - by WastedSpace
    Hi, Having a real head scratching moment... I have a site where there is a footer div that always sits at the bottom of the screen (26px high), and above that I have an iFrame which sizes to 100% of the remaining height. This works well. Even clicking on anchor links inside the iframe works as it should in all browsers (apart from IE6). Unfortunately I still have to support IE6. What is happening in IE6 is that the footer jumps up the page with the iframe still above it when I click on an anchor link. The top part of the iframe is cut off. Even the iframe's scroll bars disappear under the top of the browser. I have created some screen shots to show you what I mean. I have blurred out the actual data for now. How it should look (and does look) in other browsers: http://img100.imageshack.us/i/screen1om.jpg/ How it looks in IE6 before clicking on an anchor link: http://img532.imageshack.us/i/screen2e.jpg/ (I had to make the iframe's height 95%, because if I set it to 100% height weirdly it wouldn't show anything...) How it looks in IE6 after clicking on an anchor link: http://img214.imageshack.us/i/screen3g.jpg/ It's hard for me to show the fool code I am using, as there are lots of other things going on (of which I'm confident doesn't affect the layout), so will try to summarise: The html code (simplified): <div id="ifra"><iframe src="home.php" frameborder="0" name="content_pane" id="content_pane" marginheight="10" marginwidth="10"></iframe></div> <h1 class="toolbar"><a id="footerlink">Site Name</a></h1> The CSS (simplified): html, body { overflow: hidden; } html, body, iframe { height: 100%; } body { padding: 0; margin: 0; } #ifra, iframe { position: absolute; width: 100%; left: 0; } #ifra { top: 0px; bottom: 26px; } iframe { border: 0 none; } .toolbar { height: 26px; background-color: #C2C7C9; position: fixed; bottom: 0; width: 100%; background-image: url(bg.png); background-repeat: repeat-x; background-position: left top; } IE8 specific CSS: #ifra, .toolbar { position: fixed; } IE7 specific CSS: html { padding: 0px; } #ifra, iframe { position: absolute; } #ifra { top: 0px; bottom: 26px; } * html body { padding /**/: 100px 0 50px 0; overflow-y /**/: hidden; } IE6 specific CSS: .toolbar { position: fixed; } * html { overflow-y: hidden; } * html body { overflow-y: auto; height: 100%; } * html .toolbar { position: absolute; } iframe { height: 95%; } #ifra { height: 100%; } I know it's not ideal not seeing the full code, but just wondering if there is anything jumping out at anyone from these lines of code? By the way I did consider dropping the div surrounding the iframe, but for some reason the scroll bars would disappear under the footer in all browsers... Thanks for looking! Ali.

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  • NullPointerException in com.sun.tools.jxc.SchemaGenTask

    - by David Collie
    Given this ant script: <?xml version="1.0" encoding="UTF-8"?> <project name="projectname" default="generate-schema" basedir="."> <taskdef name="schemagen" classname="com.sun.tools.jxc.SchemaGenTask"> <classpath> <fileset dir="../BuildJars/lib" includes="*.jar" /> </classpath> </taskdef> <target name="generate-schema"> <schemagen srcdir="src/gb/informaticasystems/messages" destdir="schema"> <schema namespace="http://www.informatica-systems.co.uk/aquarius/messages/1.0" file="messages-1.0.xsd" /> </schemagen> </target> </project> I am getting this error: Buildfile: C:\Users\davidcollie\workspace\aquarius-feature\AquariusServerLibrary\schemagen.xml generate-schema: [schemagen] Generating schema from 4 source files [schemagen] Problem encountered during annotation processing; [schemagen] see stacktrace below for more information. [schemagen] java.lang.NullPointerException [schemagen] at com.sun.tools.jxc.model.nav.APTNavigator$2.onDeclaredType(APTNavigator.java:428) [schemagen] at com.sun.tools.jxc.model.nav.APTNavigator$2.onClassType(APTNavigator.java:402) [schemagen] at com.sun.tools.jxc.model.nav.APTNavigator$2.onClassType(APTNavigator.java:456) [schemagen] at com.sun.istack.tools.APTTypeVisitor.apply(APTTypeVisitor.java:27) [schemagen] at com.sun.tools.jxc.model.nav.APTNavigator.getBaseClass(APTNavigator.java:109) [schemagen] at com.sun.tools.jxc.model.nav.APTNavigator.getBaseClass(APTNavigator.java:85) [schemagen] at com.sun.xml.bind.v2.model.impl.PropertyInfoImpl.getIndividualType(PropertyInfoImpl.java:190) [schemagen] at com.sun.xml.bind.v2.model.impl.PropertyInfoImpl.<init>(PropertyInfoImpl.java:132) [schemagen] at com.sun.xml.bind.v2.model.impl.MapPropertyInfoImpl.<init>(MapPropertyInfoImpl.java:67) [schemagen] at com.sun.xml.bind.v2.model.impl.ClassInfoImpl.createMapProperty(ClassInfoImpl.java:917) [schemagen] at com.sun.xml.bind.v2.model.impl.ClassInfoImpl.addProperty(ClassInfoImpl.java:874) [schemagen] at com.sun.xml.bind.v2.model.impl.ClassInfoImpl.findGetterSetterProperties(ClassInfoImpl.java:993) [schemagen] at com.sun.xml.bind.v2.model.impl.ClassInfoImpl.getProperties(ClassInfoImpl.java:303) [schemagen] at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:243) [schemagen] at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:209) [schemagen] at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:315) [schemagen] at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:330) [schemagen] at com.sun.tools.xjc.api.impl.j2s.JavaCompilerImpl.bind(JavaCompilerImpl.java:90) [schemagen] at com.sun.tools.jxc.apt.SchemaGenerator$1.process(SchemaGenerator.java:115) [schemagen] at com.sun.mirror.apt.AnnotationProcessors$CompositeAnnotationProcessor.process(AnnotationProcessors.java:60) [schemagen] at com.sun.tools.apt.comp.Apt.main(Apt.java:454) [schemagen] at com.sun.tools.apt.main.JavaCompiler.compile(JavaCompiler.java:258) [schemagen] at com.sun.tools.apt.main.Main.compile(Main.java:1102) [schemagen] at com.sun.tools.apt.main.Main.compile(Main.java:964) [schemagen] at com.sun.tools.apt.Main.processing(Main.java:95) [schemagen] at com.sun.tools.apt.Main.process(Main.java:85) [schemagen] at com.sun.tools.apt.Main.process(Main.java:67) [schemagen] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [schemagen] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) [schemagen] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [schemagen] at java.lang.reflect.Method.invoke(Method.java:597) [schemagen] at com.sun.tools.jxc.AptBasedTask$InternalAptAdapter.execute(AptBasedTask.java:97) [schemagen] at com.sun.tools.jxc.AptBasedTask.compile(AptBasedTask.java:144) [schemagen] at org.apache.tools.ant.taskdefs.Javac.execute(Javac.java:820) [schemagen] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:288) [schemagen] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [schemagen] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) [schemagen] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [schemagen] at java.lang.reflect.Method.invoke(Method.java:597) [schemagen] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:105) [schemagen] at org.apache.tools.ant.Task.perform(Task.java:348) [schemagen] at org.apache.tools.ant.Target.execute(Target.java:357) [schemagen] at org.apache.tools.ant.Target.performTasks(Target.java:385) [schemagen] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1329) [schemagen] at org.apache.tools.ant.Project.executeTarget(Project.java:1298) [schemagen] at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41) [schemagen] at org.eclipse.ant.internal.ui.antsupport.EclipseDefaultExecutor.executeTargets(EclipseDefaultExecutor.java:32) [schemagen] at org.apache.tools.ant.Project.executeTargets(Project.java:1181) [schemagen] at org.eclipse.ant.internal.ui.antsupport.InternalAntRunner.run(InternalAntRunner.java:423) [schemagen] at org.eclipse.ant.internal.ui.antsupport.InternalAntRunner.main(InternalAntRunner.java:137) BUILD FAILED C:\Users\davidcollie\workspace\aquarius-feature\AquariusServerLibrary\schemagen.xml:11: schema generation failed Total time: 1 second Any ideas?

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  • How do I use C# and ADO.NET to query an Oracle table with a spatial column of type SDO_GEOMETRY?

    - by John Donahue
    My development machine is running Windows 7 Enterprise, 64-bit version. I am using Visual Studio 2010 Release Candidate. I am connecting to an Oracle 11g Enterprise server version 11.1.0.7.0. I had a difficult time locating Oracle client software that is made for 64-bit Windows systems and eventually landed here to download what I assume is the proper client connectivity software. I added a reference to "Oracle.DataAccess" which is version 2.111.6.0 (Runtime Version is v2.0.50727). I am targeting .NET CLR version 4.0 since all properties of my VS Solution are defaults and this is 2010 RC. I was then able to write a console application in C# that established connectivity, executed a SELECT statement, and properly returned data when the table in question does NOT contain a spatial column. My problem is that this no longer works when the table I query has a column of type SDO_GEOMETRY in it. Below is the simple console application I am trying to run that reproduces the problem. When the code gets to the line with the "ExecuteReader" command, an exception is raised and the message is "Unsupported column datatype". using System; using System.Data; using Oracle.DataAccess.Client; namespace ConsoleTestOracle { class Program { static void Main(string[] args) { string oradb = string.Format("Data Source={0};User Id={1};Password={2};", "hostname/servicename", "login", "password"); try { using (OracleConnection conn = new OracleConnection(oradb)) { conn.Open(); OracleCommand cmd = new OracleCommand(); cmd.Connection = conn; cmd.CommandText = "select * from SDO_8307_2D_POINTS"; cmd.CommandType = CommandType.Text; OracleDataReader dr = cmd.ExecuteReader(); } } catch (Exception e) { string error = e.Message; } } } } The fact that this code works when used against a table that does not contain a spatial column of type SDO_GEOMETRY makes me think I have my windows 7 machine properly configured so I am surprised that I get this exception when the table contains different kinds of columns. I don't know if there is some configuration on my machine or the Oracle machine that needs to be done, or if the Oracle client software I have installed is wrong, or old and needs to be updated. Here is the SQL I used to create the table, populate it with some rows containing points in the spatial column, etc. if you want to try to reproduce this exactly. SQL Create Commands: create table SDO_8307_2D_Points (ObjectID number(38) not null unique, TestID number, shape SDO_GEOMETRY); Insert into SDO_8307_2D_Points values (1, 1, SDO_GEOMETRY(2001, 8307, null, SDO_ELEM_INFO_ARRAY(1, 1, 1), SDO_ORDINATE_ARRAY(10.0, 10.0))); Insert into SDO_8307_2D_Points values (2, 2, SDO_GEOMETRY(2001, 8307, null, SDO_ELEM_INFO_ARRAY(1, 1, 1), SDO_ORDINATE_ARRAY(10.0, 20.0))); insert into user_sdo_geom_metadata values ('SDO_8307_2D_Points', 'SHAPE', SDO_DIM_ARRAY(SDO_DIM_ELEMENT('Lat', -180, 180, 0.05), SDO_DIM_ELEMENT('Long', -90, 90, 0.05)), 8307); create index SDO_8307_2D_Point_indx on SDO_8307_2D_Points(shape) indextype is mdsys.spatial_index PARAMETERS ('sdo_indx_dims=2' ); Any advice or insights would be greatly appreciated. Thank you.

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  • WPF Binding Error reported when Binding appears to work fine

    - by Noldorin
    I am trying to create a custom TabItem template/style in my WPF 4.0 application (using VS 2010 Pro RTM), but inspite of everything seeming to work correctly, I am noticing a binding error in the trace window. The resource dictionary XAML I use to style the TabItems of a TabControl is given in full here. (Just create a simple TabControl with several items and apply the given ResourceDictionary to test it out.) Specifically, the error is occurring due to the following line (discovered through trial and error testing, since Visual Studio isn't actually reporting it at design tim <TranslateTransform X="{Binding ActualWidth, ElementName=leftSideBorderPath}"/> The full error given in the trace (Ouput window) is the following: System.Windows.Data Error: 2 : Cannot find governing FrameworkElement or FrameworkContentElement for target element. BindingExpression:Path=ActualWidth; DataItem=null; target element is 'TranslateTransform' (HashCode=35345840); target property is 'X' (type 'Double') The error occurs on load and is repeated 5 times then (note that I have 3 tab items in my example). It also occurs consistently and repeatedly whenever for the Window is resized, for example - filling the Output window. Perhaps every time the TabItem layout is updated? And again, though it is not reported, the error very much seems to be due to the fact that I am binding to any element at all, not specifically leftSideBorderPath or the the ActualWidth propertry. For example, changing this line to the following fixes things. <TranslateTransform X="25"/> Unfortunately, hard-coding the value isn't really an option. This issue seems very strange to me in that the binding does appear to be giving the correct results. (Inspecting the X value of the TranslateTransform at runtime clearly shows the correct bound value, and the ClipGeometry when viewed is exactly what it hsould be.) Neither Visual Studio nor WPF seems to be giving me any more information on the cause of the error perhaps (setting PresentationTraceSources.TraceLevel to High doesn't help), yet the fact that things are working despite the error being reported inclines me to think that this is some fringe-case WPF bug. As a side note, the Visual Studio WPF designer and XAML editor are giving me a problem with the following line: <PathGeometry Figures="{Binding Source={StaticResource TabSideFillFigures}}"/> Although WPF (at runtime) is perfectly happy binding Figures to the TabSideFillFigures string, with the Binding enforcing the use of the TypeConverter, the XAML editor and WPF designer are complaining. All the XAML code for the ControlTemplate is underlined and I get the following errors in the Error List: Error 9 '{DependencyProperty.UnsetValue}' is not a valid value for the 'System.Windows.Controls.Control.Template' property on a Setter. C:\Users\Alex\Documents\Visual Studio 2010\Projects\Ircsil\devel\Ircsil\MainWindow.xaml 1 1 Ircsil Error 10 Object reference not set to an instance of an object. C:\Users\Alex\Documents\Visual Studio 2010\Projects\Ircsil\devel\Ircsil\Skins\Default\MainSkin.xaml 58 17 Ircsil Again, to repeat, everything works perfectly well at runtime, which is what makes this particularly odd... Could someone perhaps shed some light on these issues, in particular the first (which seems to be a potential WPF bug), and the latter (which seems to be a Visual Studio bug). Any sort of feedback or suggestions would be much appreciated!

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  • Salesforce/PHP - Bulk Outbound message (SOAP), Time out issue - See update #2

    - by Phill Pafford
    Salesforce can send up to 100 requests inside 1 SOAP message. While sending this type of Bulk Ooutbound message request my PHP script finishes executing but SF fails to accept the ACK used to clear the message queue on the Salesforce side of things. Looking at the Outbound message log (monitoring) I see all the messages in a pending state with the Delivery Failure Reason "java.net.SocketTimeoutException: Read timed out". If my script has finished execution, why do I get this error? I have tried these methods to increase the execution time on my server as I have no access on the Salesforce side: set_time_limit(0); // in the script max_execution_time = 360 ; Maximum execution time of each script, in seconds max_input_time = 360 ; Maximum amount of time each script may spend parsing request data memory_limit = 32M ; Maximum amount of memory a script may consume I used the high settings just for testing. Any thoughts as to why this is failing the ACK delivery back to Salesforce? Here is some of the code: This is how I accept and send the ACK file for the imcoming SOAP request $data = 'php://input'; $content = file_get_contents($data); if($content) { respond('true'); } else { respond('false'); } The respond function function respond($tf) { $ACK = <<<ACK <?xml version = "1.0" encoding = "utf-8"?> <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <soapenv:Body> <notifications xmlns="http://soap.sforce.com/2005/09/outbound"> <Ack>$tf</Ack> </notifications> </soapenv:Body> </soapenv:Envelope> ACK; print trim($ACK); } These are in a generic script that I include into the script that uses the data for a specific workflow. I can process about 25 requests (That are in 1 SOAP response) but once I go over that I get the timeout error in the Salesforce queue. for 50 requests is usually takes my PHP script 86.77 seconds. Could it be Apache? PHP? I have also tested just accepting the 100 request SOAP response and just accepting and sending the ACK the queue clears out, so I know it's on my side of things. I show no errors in the apache log, the script runs fine. I did find some info on the Salesforce site but still no luck. Here is the link. Also I'm using the PHP Toolkit 11 (From Salesforce). Other forum with good SF help Thanks for any insight into this, --Phill UPDATE: If I receive the incoming message and print the response, should this happen first regardless if I do anything else after? Or does it wait for my process to finish and then print the response? UPDATE #2: okay I think I have the problem: PHP uses the single thread processing approach and will not send back the ACK file until the thread has completed it's processing. Is there a way to make this a mutli thread process? Thread #1 - accept the incoming SOAP request and send back the ACK Thread #2 - Process the SOAP request I know I could break it up into like a DB table or flat file, but is there a way to accomplish this without doing that? I'm going to try to close the socket after the ACK submission and continue the processing, cross my fingers it will work.

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  • UIScrollView zoomToRect not zooming to given rect (created from UITouch CGPoint)

    - by pmhart
    My application has a UIScrollView with one subview. The subview is an extended UIView which prints a PDF page to itself using layers in the drawLayer event. Zooming using the built in pinching works great. setZoomScale also works as expected. I have been struggling with the zoomToRect function. I found an example online which makes a CGRect zoomRect variable from a given CGPoint. In the touchesEnded function, if there was a double tap and they are all the way zoomed out, I want to zoom in to that PDFUIView I created as though they were pinching out with the center of the pinch where they double tapped. So assume that I pass the UITouch variable to my function which utilizes zoomToRect if they double tap. I started with the following function I found on apples site: http://developer.apple.com/iphone/library/documentation/WindowsViews/Conceptual/UIScrollView_pg/ZoomZoom/ZoomZoom.html The following is a modified version for my UIScrollView extended class: - (void)zoomToCenter:(float)scale withCenter:(CGPoint)center { CGRect zoomRect; zoomRect.size.height = self.frame.size.height / scale; zoomRect.size.width = self.frame.size.width / scale; zoomRect.origin.x = center.x - (zoomRect.size.width / 2.0); zoomRect.origin.y = center.y - (zoomRect.size.height / 2.0); //return zoomRect; [self zoomToRect:zoomRect animated:YES]; } When I do this, the UIScrollView seems to zoom using the bottom right edge of the zoomRect above and not the center. If I make UIView like this UIView *v = [[UIView alloc] initWithFrame:zoomRect]; [v setBackgroundColor:[UIView redColor]]; [self addSubview:v]; The red box shows up with the touch point dead in the center. Please note: I am writing this from my PC, I recall messing around with the divided by two part on my Mac, so just assume that this draws a rect with the touch point in the center. If the UIView drew off center but zoomed to the right spot it would be all good. However, what happens is when it preforms the zoomToRect it seems to use the bottom right off the zoomRect at the top left of the zoomed in results. Also, I noticed that depending on where I click on the UIScrollView, it anchors to diffrent spots. It almost seems like there is a cross down the middle and it's reflecting the points somehow as though anywhere left of the middle is a negative reflection and anywhere right of the middle is a positive reflection? This seems to complicated, shouldn't it just zoom to the rect that was drawn as the UIView was able to draw? I used a lot of research to figure out how to create a PDF that scales in high quality, so I am assuming that using the CALayer may be throwing off the coordinate system? But to the UIScrollView it should just treat it as a view with 768x985 dimensions. This is sort of advanced, please assume the code for creating the zoomRect is all good. There is something deeper with the CALayer in the UIView which is in the UIScrollView....

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  • Functions registered with ExternalInterface.addCallback not available in Javascript

    - by Selene
    I'm working on a Flash game that needs to call some Javascript on the page and get data back from it. Calling Javascript from Flash works. Calling the Flash functions from Javascript (often) doesn't. I'm using the Gaia framework. What happens: The swf is loaded in with SWFObject There's a button in the Flash file. On click, it uses ExternalInterface.call() to call a Javascript function. This works. The Javascript function calls a Flash function that was exposed with ExternalInterface.addCallback(). Sometimes, the Javascript produces the following error: TypeError: myFlash.testCallback is not a function. When the error happens, it affects all functions registered with addCallback(). Gaia and some of its included libraries use addCallback(), and calling those functions from Javascript also produces the TypeError. Waiting a long time before pressing the button in Flash doesn't solve the error. Having Flash re-try addCallback() periodically doesn't solve the error When the error occurs, ExternalInterface.available = true and ExternalInterface.objectID contains the correct name for the Flash embed object. When the error occurs, document.getElementById('myflashcontent') correctly returns the Flash embed object. From my Page class: public class MyPage extends AbstractPage { // declarations of stage instances and class variables // other functions override public function transitionIn():void { send_button.addEventListener(MouseEvent.MOUSE_UP, callJS); exposeCallbacks(); super.transitionIn(); } private function exposeCallbacks():void { trace("exposeCallbacks()"); if (ExternalInterface.available) { trace("ExternalInterface.objectID: " + ExternalInterface.objectID); try { ExternalInterface.addCallback("testCallback", simpleTestCallback); trace("called ExternalInterface.addCallback"); } catch (error:SecurityError) { trace("A SecurityError occurred: " + error.message + "\n"); } catch (error:Error) { trace("An Error occurred: " + error.message + "\n"); } } else { trace("exposeCallbacks() - ExternalInterface not available"); } } private function simpleTestCallback(str:String):void { trace("simpleTestCallback(str=\"" + str + "\")"); } private function callJS(e:Event):void { if (ExternalInterface.available) { ExternalInterface.call("sendTest", "name", "url"); } else { trace("callJS() - ExternalInterface not available"); } } } My Javascript: function sendTest(text, url) { var myFlash = document.getElementById("myflashcontent"); var callbackStatus = ""; callbackStatus += '\nmyFlash[testCallback]: ' + myFlash['testCallback']; //console.log(callbackStatus); var errors = false; try { myFlash.testCallback("test string"); } catch (err) { alert("Error: " + err.toString()); error = true; } if (!error) { alert("Success"); } } var params = { quality: "high", scale: "noscale", wmode: "transparent", allowscriptaccess: "always", bgcolor: "#000000" }; var flashVars = { siteXML: "xml/site.xml" }; var attributes = { id: "myflashcontent", name: "myflashcontent" }; // load the flash movie. swfobject.embedSWF("http://myurl.com/main.swf?v2", "myflashcontent", "728", "676", "10.0.0", serverRoot + "expressInstall.swf", flashVars, params, attributes, function(returnObj) { console.log('Returned ' + returnObj.success); if (returnObj.success) { returnObj.ref.focus(); } });

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  • Does Apache ever give incorrect "out of threads" errors?

    - by Eli Courtwright
    Lately our Apache web server has been giving us this error multiple times per day: [Tue Apr 06 01:07:10 2010] [error] Server ran out of threads to serve requests. Consider raising the ThreadsPerChild setting We raised our ThreadsPerChild setting from 50 to 100, but we still get the error. Our access logs indicate that these errors never even happen at periods of high load. For example, here's an excerpt from our access log (ip addresses and some urls are edited for privacy). As you can see, the above error happened at 1:07 and only a small handful of requests occurred in the several minutes leading up to the error: 99.88.77.66 - - [06/Apr/2010:00:59:33 -0400] "GET /WebRepository/jquery/jquery-ui-1.7.1.custom/css/smoothness/images/ui-icons_222222_256x240.png HTTP/1.1" 304 - 99.88.77.66 - - [06/Apr/2010:00:59:34 -0400] "GET /WebRepository/jquery/jquery-ui-1.7.1.custom/css/smoothness/images/ui-bg_glass_75_dadada_1x400.png HTTP/1.1" 200 111 99.88.77.66 - - [06/Apr/2010:00:59:34 -0400] "GET /WebRepository/jquery/jquery-ui-1.7.1.custom/css/smoothness/images/ui-bg_glass_75_dadada_1x400.png HTTP/1.1" 200 111 99.88.77.66 - mpeu [06/Apr/2010:00:59:40 -0400] "GET /some/dynamic/content HTTP/1.1" 200 145049 55.44.33.22 - mpeu [06/Apr/2010:01:06:56 -0400] "GET /other/dynamic/content HTTP/1.1" 200 12311 55.44.33.22 - - [06/Apr/2010:01:06:56 -0400] "GET /WebRepository/jquery/jquery-ui-1.7.1.custom/css/smoothness/jquery-ui-1.7.1.custom.css HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:56 -0400] "GET /WebRepository/jquery/jquery-ui-1.7.1.custom/js/jquery-1.3.2.min.js HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:56 -0400] "GET /WebRepository/jquery/jquery-ui-1.7.1.custom/js/jquery-ui-1.7.1.custom.min.js HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:56 -0400] "GET /WebRepository/jquery.tablesorter.min.js HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:56 -0400] "GET /WebRepository/date.js HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:56 -0400] "GET /WebRepository/pdfs/image1.gif HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:56 -0400] "GET /WebRepository/pdfs/image2.png HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:56 -0400] "GET /WebRepository/pdfs/image3.png HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:56 -0400] "GET /WebRepository/pdfs/image4.png HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:56 -0400] "GET /WebRepository/pdfs/image5.png HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:56 -0400] "GET /WebRepository/pdfs/image6.png HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:56 -0400] "GET /WebRepository/pdfs/image7.png HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:57 -0400] "GET /WebRepository/pdfs/image8.png HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:57 -0400] "GET /WebRepository/pdfs/image9.png HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:57 -0400] "GET /WebRepository/pdfs/imageA.png HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:57 -0400] "GET /WebRepository/jquery/jquery-ui-1.7.1.custom/css/smoothness/images/ui-bg_flat_75_ffffff_40x100.png HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:59 -0400] "GET /WebRepository/jquery/jquery-ui-1.7.1.custom/css/smoothness/images/ui-bg_highlight-soft_75_cccccc_1x100.png HTTP/1.1" 304 - 55.44.33.22 - - [06/Apr/2010:01:06:59 -0400] "GET /WebRepository/jquery/jquery-ui-1.7.1.custom/css/smoothness/images/ui-bg_glass_75_e6e6e6_1x400.png HTTP/1.1" 200 110 55.44.33.22 - - [06/Apr/2010:01:06:59 -0400] "GET /WebRepository/jquery/jquery-ui-1.7.1.custom/css/smoothness/images/ui-bg_glass_75_e6e6e6_1x400.png HTTP/1.1" 200 110 11.22.33.44 - mpeu [06/Apr/2010:01:18:03 -0400] "GET /other/dynamic/content HTTP/1.1" 200 12311 11.22.33.44 - - [06/Apr/2010:01:18:03 -0400] "GET /WebRepository/jquery/jquery-ui-1.7.1.custom/js/jquery-1.3.2.min.js HTTP/1.1" 304 - 11.22.33.44 - - [06/Apr/2010:01:18:04 -0400] "GET /WebRepository/jquery/jquery-ui-1.7.1.custom/css/smoothness/jquery-ui-1.7.1.custom.css HTTP/1.1" 200 27374 11.22.33.44 - - [06/Apr/2010:01:18:04 -0400] "GET /WebRepository/jquery/jquery-ui-1.7.1.custom/js/jquery-ui-1.7.1.custom.min.js HTTP/1.1" 304 - 11.22.33.44 - - [06/Apr/2010:01:18:04 -0400] "GET /WebRepository/jquery.tablesorter.min.js HTTP/1.1" 200 12795 11.22.33.44 - - [06/Apr/2010:01:18:04 -0400] "GET /WebRepository/date.js HTTP/1.1" 200 25809 For what it's worth, we're running the version of Apache that ships with Oracle 10g (some 2.0 version), and we're using mod_plsql to generate our dynamic content. Since the Apache server runs as a separate process and the database doesn't record any problems when this error occurs, I'm doubtful that Oracle is the problem. Unfortunately, the errors are freaking out our sysadmins, who are inclined to blame any and all problems which occur with the server on this error. Is this a known bug in Apache that I simply haven't been able to find any reference to through Google?

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  • Simple animation using C#/Windows Forms

    - by clintp
    I need to knock out a quick animation in C#/Windows Forms for a Halloween display. Just some 2D shapes moving about on a solid background. Since this is just a quick one-off project I really don't want to install and learn an entire new set of tools for this. (DirectX dev kits, Silverlight, Flash, etc..) I also have to install this on multiple computers so anything beyond the basic .Net framework (2.0) would be a pain in the arse. For tools I've got VS2k8, 25 years of development experience, a wheelbarrow, holocaust cloak, and about 2 days to knock this out. I haven't done animation since using assembler on my Atari 130XE (hooray for page flipping and player/missile graphics!) Advice? Here's some of the things I'd like to know: I can draw on any empty widget (like a panel) by fiddling with it's OnPaint handler, right? That's how I'd draw a custom widget. Is there a better technique than this? Is there a page-flipping technique for this kind of thing in Windows Forms? I'm not looking for a high frame rate, just as little flicker/drawing as necessary. Thanks. Post Mortem Edit ... "a couple of coding days later" Well, the project is done. The links below came in handy although a couple of them were 404. (I wish SO would allow more than one reply to be marked "correct"). The biggest problem I had to overcome was flickering, and a persistent bug when I tried to draw on the form directly. Using the OnPaint event for the Form: bad idea. I never got that to work; lots of mysterious errors (stack overflows, or ArgumentNullExceptions). I wound up using a panel sized to fill the form and that worked fine. Using the OnPaint method is slow anyway. Somewhere online I read that building the PaintEventArgs was slow, and they weren't kidding. Lots of flickering went away when I abandoned this. Skip the OnPaint/Invalidate() and just paint it yourself. Setting all of the "double buffering" options on the form still left some flicker that had to be fixed. (And I found conflicting docs that said "set them on the control" and "set them on the form". Well controls don't have a .SetStyle() method.) I haven't tested without them, so they might be doing something (this is the form): this.SetStyle(ControlStyles.UserPaint, true); this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true); this.SetStyle(ControlStyles.AllPaintingInWmPaint, true); So the workhorse of the code wound up looking like (pf is the panel control): void PaintPlayField() { Bitmap bufl = new Bitmap(pf.Width, pf.Height); using (Graphics g = Graphics.FromImage(bufl)) { g.FillRectangle(Brushes.Black, new Rectangle(0, 0, pf.Width, pf.Height)); DrawItems(g); DrawMoreItems(g); pf.CreateGraphics().DrawImageUnscaled(bufl, 0, 0); } } And I just called PaintPlayField from the inside of my Timer loop. No flicker at all.

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  • C++ custom exceptions: run time performance and passing exceptions from C++ to C

    - by skyeagle
    I am writing a custom C++ exception class (so I can pass exceptions occuring in C++ to another language via a C API). My initial plan of attack was to proceed as follows: //C++ myClass { public: myClass(); ~myClass(); void foo() // throws myException int foo(const int i, const bool b) // throws myException } * myClassPtr; // C API #ifdef __cplusplus extern "C" { #endif myClassPtr MyClass_New(); void MyClass_Destroy(myClassPtr p); void MyClass_Foo(myClassPtr p); int MyClass_FooBar(myClassPtr p, int i, bool b); #ifdef __cplusplus }; #endif I need a way to be able to pass exceptions thrown in the C++ code to the C side. The information I want to pass to the C side is the following: (a). What (b). Where (c). Simple Stack Trace (just the sequence of error messages in order they occured, no debugging info etc) I want to modify my C API, so that the API functions take a pointer to a struct ExceptionInfo, which will contain any exception info (if an exception occured) before consuming the results of the invocation. This raises two questions: Question 1 1. Implementation of each of the C++ methods exposed in the C API needs to be enclosed in a try/catch statement. The performance implications for this seem quite serious (according to this article): "It is a mistake (with high runtime cost) to use C++ exception handling for events that occur frequently, or for events that are handled near the point of detection." At the same time, I remember reading somewhere in my C++ days, that all though exception handling is expensive, it only becmes expensive when an exception actually occurs. So, which is correct?. what to do?. Is there an alternative way that I can trap errors safely and pass the resulting error info to the C API?. Or is this a minor consideration (the article after all, is quite old, and hardware have improved a bit since then). Question 2 I wuld like to modify the exception class given in that article, so that it contains a simple stack trace, and I need some help doing that. Again, in order to make the exception class 'lightweight', I think its a good idea not to include any STL classes, like string or vector (good idea/bad idea?). Which potentially leaves me with a fixed length C string (char*) which will be stack allocated. So I can maybe just keep appending messages (delimted by a unique separator [up to maximum length of buffer])... Its been a while since I did any serious C++ coding, and I will be grateful for the help. BTW, this is what I have come up with so far (I am intentionally, not deriving from std::exception because of the performance reasons mentioned in the article, and I am instead, throwing an integral exception (based on an exception enumeration): class fast_exception { public: fast_exception(int what, char const* file=0, int line=0) : what_(what), line_(line), file_(file) {/*empty*/} int what() const { return what_; } int line() const { return line_; } char const* file() const { return file_; } private: int what_; int line_; char const[MAX_BUFFER_SIZE] file_; }

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  • Maze not being random.

    - by Matt Habel
    Hey there, I am building a program that generates a maze so I can later translate the path to my graphical part. I have most of it working, however, every time you can just take the east and south routes, and you'll get to the end. Even if I set the width as high as 64, so the maze is 64*64, I'm able to choose those 2 options and get to the end every time. I really don't understand why it is doing that. The code is below, it's fairly easy to understand. import random width = 8 def check(x,y): """Figures out the directions that Gen can move while""" if x-1 == -1: maze[x][y][3] = 0 if x+1 == width + 1: maze[x][y][1] = 0 if y+1 == width + 1: maze[x][y][2] = 0 if y-1 == -1: maze[x][y][0] = 0 if x + 1 in range(0,width) and visited[x+1][y] == False: maze[x][y][1] = 2 if x - 1 in range(0,width) and visited[x-1][y] == False: maze[x][y][3] = 2 if y + 1 in range(0,width) and visited[x][y+1] == False: maze[x][y][2] = 2 if y - 1 in range(0,width) and visited[x][y-1] == False: maze[x][y][0] = 2 def possibleDirs(x,y): """Figures out the ways that the person can move in each square""" dirs = [] walls = maze[x][y] if walls[0] == 1: dirs.append('n') if walls[1] == 1: dirs.append('e') if walls[2] == 1: dirs.append('s') if walls[3] == 1: dirs.append('w') return dirs def Gen(x,y): """Generates the maze using a depth-first search and recursive backtracking.""" visited[x][y] = True dirs = [] check(x,y) if maze[x][y][0] == 2: dirs.append(0) if maze[x][y][1] == 2: dirs.append(1) if maze[x][y][2] == 2: dirs.append(2) if maze[x][y][3] == 2: dirs.append(3) print dirs if len(dirs): #Randonly selects a derection for the current square to move past.append(current[:]) pos = random.choice(dirs) maze[x][y][pos] = 1 if pos == 0: current[1] -= 1 maze[x][y-1][2] = 1 if pos == 1: current[0] += 1 maze[x+1][y][3] = 1 if pos == 2: current[1] += 1 maze[x][y+1][0] = 1 if pos == 3: current[0] -= 1 maze[x-1][y][1] = 1 else: #If there's nowhere to go, go back one square lastPlace = past.pop() current[0] = lastPlace[0] current[1] = lastPlace[1] #Build the initial values for the maze to be replaced later maze = [] visited = [] past = [] #Generate empty 2d list with a value for each of the xy coordinates for i in range(0,width): maze.append([]) for q in range(0, width): maze[i].append([]) for n in range(0, 4): maze[i][q].append(4) #Makes a list of falses for all the non visited places for x in range(0, width): visited.append([]) for y in range(0, width): visited[x].append(False) dirs = [] print dirs current = [0,0] #Generates the maze so every single square has been filled. I'm not sure how this works, as it is possible to only go south and east to get to the final position. while current != [width-1, width-1]: Gen(current[0], current[1]) #Getting the ways the person can move in each square for i in range(0,width): dirs.append([]) for n in range(0,width): dirs[i].append([]) dirs[i][n] = possibleDirs(i,n) print dirs print visited pos = [0,0] #The user input part of the maze while pos != [width - 1, width - 1]: dirs = [] print pos if maze[pos[0]][pos[1]][0] == 1: dirs.append('n') if maze[pos[0]][pos[1]][1] == 1: dirs.append('e') if maze[pos[0]][pos[1]][2] == 1: dirs.append('s') if maze[pos[0]][pos[1]][3] == 1: dirs.append('w') print dirs path = raw_input("What direction do you want to go: ") if path not in dirs: print "You can't go that way!" continue elif path.lower() == 'n': pos[1] -= 1 elif path.lower() == 'e': pos[0] += 1 elif path.lower() == 's': pos[1] += 1 elif path.lower() == 'w': pos[0] -= 1 print"Good job!" As you can see, I think the problem is at the point where I generate the maze, however, when I just have it go until the current point is at the end, it doesn't fill every maze and is usually just one straight path. Thanks for helping. Update: I have changed the for loop that generates the maze to a simple while loop and it seems to work much better. It seems that when the for loop ran, it didn't go recursively, however, in the while loop it's perfectly fine. However, now all the squares do not fill out.

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  • GAE formpreview

    - by Niklas R
    I'm trying to enable form preview with Google App Engine. Getting the following error message I suspect being mistaken somewhere: ... handler = handler_class() TypeError: __call__() takes at least 2 arguments (1 given) Can you tell what's wrong with my attempt? Here is some of the code. from django.contrib.formtools.preview import FormPreview class AFormPreview(FormPreview): def done(self, request, cleaned_data): # Do something with the cleaned_data, then redirect # to a "success" page. self.response.out.write('Done!') class AForm(djangoforms.ModelForm): text = forms.CharField(widget=forms.Textarea(attrs={'rows':'11','cols':'70','class':'foo'}),label=_("content").capitalize()) def clean(self): cleaned_data = self.clean_data name = cleaned_data.get("name") if not name: raise forms.ValidationError("No name.") # Always return the full collection of cleaned data. return cleaned_data class Meta: model = A fields = ['category','currency','price','title','phonenumber','postaladress','name','text','email'] #change the order ... ('/aformpreview/([^/]*)', AFormPreview(AForm)), UPDATE: Here's a complete app where the preview is not working. Any ideas are most welcome: import cgi from google.appengine.api import users from google.appengine.ext import db from google.appengine.ext import webapp from google.appengine.ext.webapp import template from google.appengine.ext.webapp.util import run_wsgi_app from google.appengine.ext.db import djangoforms class Item(db.Model): name = db.StringProperty() quantity = db.IntegerProperty(default=1) target_price = db.FloatProperty() priority = db.StringProperty(default='Medium',choices=[ 'High', 'Medium', 'Low']) entry_time = db.DateTimeProperty(auto_now_add=True) added_by = db.UserProperty() class ItemForm(djangoforms.ModelForm): class Meta: model = Item exclude = ['added_by'] from django.contrib.formtools.preview import FormPreview class ItemFormPreview(FormPreview): def done(self, request, cleaned_data): # Do something with the cleaned_data, then redirect # to a "success" page. return HttpResponseRedirect('/') class MainPage(webapp.RequestHandler): def get(self): self.response.out.write('<html><body>' '<form method="POST" ' 'action="/">' '<table>') # This generates our shopping list form and writes it in the response self.response.out.write(ItemForm()) self.response.out.write('</table>' '<input type="submit">' '</form></body></html>') def post(self): data = ItemForm(data=self.request.POST) if data.is_valid(): # Save the data, and redirect to the view page entity = data.save(commit=False) entity.added_by = users.get_current_user() entity.put() self.redirect('/items.html') else: # Reprint the form self.response.out.write('<html><body>' '<form method="POST" ' 'action="/">' '<table>') self.response.out.write(data) self.response.out.write('</table>' '<input type="submit">' '</form></body></html>') class ItemPage(webapp.RequestHandler): def get(self): query = db.GqlQuery("SELECT * FROM Item ORDER BY name") for item in query: self.response.out.write('<a href="/edit?id=%d">Edit</a> - ' % item.key().id()) self.response.out.write("%s - Need to buy %d, cost $%0.2f each<br>" % (item.name, item.quantity, item.target_price)) class EditPage(webapp.RequestHandler): def get(self): id = int(self.request.get('id')) item = Item.get(db.Key.from_path('Item', id)) self.response.out.write('<html><body>' '<form method="POST" ' 'action="/edit">' '<table>') self.response.out.write(ItemForm(instance=item)) self.response.out.write('</table>' '<input type="hidden" name="_id" value="%s">' '<input type="submit">' '</form></body></html>' % id) def post(self): id = int(self.request.get('_id')) item = Item.get(db.Key.from_path('Item', id)) data = ItemForm(data=self.request.POST, instance=item) if data.is_valid(): # Save the data, and redirect to the view page entity = data.save(commit=False) entity.added_by = users.get_current_user() entity.put() self.redirect('/items.html') else: # Reprint the form self.response.out.write('<html><body>' '<form method="POST" ' 'action="/edit">' '<table>') self.response.out.write(data) self.response.out.write('</table>' '<input type="hidden" name="_id" value="%s">' '<input type="submit">' '</form></body></html>' % id) def main(): application = webapp.WSGIApplication( [('/', MainPage), ('/edit', EditPage), ('/items.html', ItemPage), ('/itemformpreview', ItemFormPreview(ItemForm)), ], debug=True) run_wsgi_app(application)

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  • Is this question too hard for a seasoned C++ architect?

    - by Monomer
    Background Information We're looking to hire a seasoned C++ architect (10+years dev, of which at least 6years must be C++ ) for a high frequency trading platform. Job advert says STL, Boost proficiency is a must with preferences to modern uses of C++. The company I work for is a Fortune 500 IB (aka finance industry), it requires passes in all the standard SHL tests (numeric, vocab, spatial etc) before interviews can commence. Everyone on the team was given the task of coming up with one question to ask the candidates during a written/typed test, please note this is the second test provided to the candidates, the first being Advanced IKM C++ test, done in the offices supervised and without internet access. People passing that do the second test. After roughly 70 candidates, my question has been determined to be statistically the worst performing - aka least number of people attempted it, furthermore even less people were able to give meaningful answers. Please note, the second test is not timed, the candidate can literally take as long as they like (we've had one person take roughly 10.5hrs) My question to SO is this, after SHL and IKM adv c++ tests, backed up with at least 6+ years C++ development experience, is it still ok not to be able to even comment about let alone come up with some loose strategy for solving the following question. The Question There is a class C with methods foo, boo, boo_and_foo and foo_and_boo. Each method takes i,j,k and l clock cycles respectively, where i < j, k < i+j and l < i+j. class C { public: int foo() {...} int boo() {...} int boo_and_foo() {...} int foo_and_boo() {...} }; In code one might write: C c; . . int i = c.foo() + c.boo(); But it would be better to have: int i = c.foo_and_boo(); What changes or techniques could one make to the definition of C, that would allow similar syntax of the original usage, but instead have the compiler generate the latter. Note that foo and boo are not commutative. Possible Solution We were basically looking for an expression templates based approach, and were willing to give marks to anyone who had even hinted or used the phrase or related terminology. We got only two people that used the wording, but weren't able to properly describe how they accomplish the task in detail. We use such techniques all over the place, due to the use of various mathematical operators for matrix and vector based calculations, for example to decide when to use IPP or hand woven implementations at compile time for a particular architecture and many other things. The particular area of software development requires microsecond response times. I believe could/should be able to teach a junior such techniques, but given the assumed caliber of candidates I expected a little more. Is this really a difficult question? Should it be removed? Or are we just not seeing the right candidates?

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  • Memory Troubles with UIImagePicker

    - by Dan Ray
    I'm building an app that has several different sections to it, all of which are pretty image-heavy. It ties in with my client's website and they're a "high-design" type outfit. One piece of the app is images uploaded from the camera or the library, and a tableview that shows a grid of thumbnails. Pretty reliably, when I'm dealing with the camera version of UIImagePickerControl, I get hit for low memory. If I bounce around that part of the app for a while, I occasionally and non-repeatably crash with "status:10 (SIGBUS)" in the debugger. On low memory warning, my root view controller for that aspect of the app goes to my data management singleton, cruises through the arrays of cached data, and kills the biggest piece, the image associated with each entry. Thusly: - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Low Memory Warning" message:@"Cleaning out events data" delegate:nil cancelButtonTitle:@"All right then." otherButtonTitles:nil]; [alert show]; [alert release]; NSInteger spaceSaved; DataManager *data = [DataManager sharedDataManager]; for (Event *event in data.eventList) { spaceSaved += [(NSData *)UIImagePNGRepresentation(event.image) length]; event.image = nil; spaceSaved -= [(NSData *)UIImagePNGRepresentation(event.image) length]; } NSString *titleString = [NSString stringWithFormat:@"Saved %d on event images", spaceSaved]; for (WondrMark *mark in data.wondrMarks) { spaceSaved += [(NSData *)UIImagePNGRepresentation(mark.image) length]; mark.image = nil; spaceSaved -= [(NSData *)UIImagePNGRepresentation(mark.image) length]; } NSString *messageString = [NSString stringWithFormat:@"And total %d on event and mark images", spaceSaved]; NSLog(@"%@ - %@", titleString, messageString); // Relinquish ownership any cached data, images, etc that aren't in use. } As you can see, I'm making a (poor) attempt to eyeball the memory space I'm freeing up. I know it's not telling me about the actual memory footprint of the UIImages themselves, but it gives me SOME numbers at least, so I can see that SOMETHING'S happening. (Sorry for the hamfisted way I build that NSLog message too--I was going to fire another UIAlertView, but realized it'd be more useful to log it.) Pretty reliably, after toodling around in the image portion of the app for a while, I'll pull up the camera interface and get the low memory UIAlertView like three or four times in quick succession. Here's the NSLog output from the last time I saw it: 2010-05-27 08:55:02.659 EverWondr[7974:207] Saved 109591 on event images - And total 1419756 on event and mark images wait_fences: failed to receive reply: 10004003 2010-05-27 08:55:08.759 EverWondr[7974:207] Saved 4 on event images - And total 392695 on event and mark images 2010-05-27 08:55:14.865 EverWondr[7974:207] Saved 4 on event images - And total 873419 on event and mark images 2010-05-27 08:55:14.969 EverWondr[7974:207] Saved 4 on event images - And total 4 on event and mark images 2010-05-27 08:55:15.064 EverWondr[7974:207] Saved 4 on event images - And total 4 on event and mark images And then pretty soon after that we get our SIGBUS exit. So that's the situation. Now my specific questions: THE time I see this happening is when the UIPickerView's camera iris shuts. I click the button to take the picture, it does the "click" animation, and Instruments shows my memory footprint going from about 10mb to about 25mb, and sitting there until the image is delivered to my UIViewController, where usage drops back to 10 or 11mb again. If we make it through that without a memory warning, we're golden, but most likely we don't. Anything I can do to make that not be so expensive? Second, I have NSZombies enabled. Am I understanding correctly that that's actually preventing memory from being freed? Am I subjecting my app to an unfair test environment? Third, is there some way to programmatically get my memory usage? Or at least the usage for a UIImage object? I've scoured the docs and don't see anything about that.

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  • Calling the same xsl:template for different node names of the same complex type

    - by CraftyFella
    Hi, I'm trying to keep my xsl DRY and as a result I wanted to call the same template for 2 sections of an XML document which happen to be the same complex type (ContactDetails and AltContactDetails). Given the following XML: <?xml version="1.0" encoding="UTF-8"?> <RootNode> <Name>Bob</Name> <ContactDetails> <Address> <Line1>1 High Street</Line1> <Town>TownName</Town> <Postcode>AB1 1CD</Postcode> </Address> <Email>[email protected]</Email> </ContactDetails> <AltContactDetails> <Address> <Line1>3 Market Square</Line1> <Town>TownName</Town> <Postcode>EF2 2GH</Postcode> </Address> <Email>[email protected]</Email> </AltContactDetails> </RootNode> I wrote an XSL Stylesheet as follows: <?xml version="1.0" encoding="UTF-8"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"> <xsl:template match="/"> <PersonsName> <xsl:value-of select="RootNode/Name"/> </PersonsName> <xsl:call-template name="ContactDetails"> <xsl:with-param name="data"><xsl:value-of select="RootNode/ContactDetails"/></xsl:with-param> <xsl:with-param name="elementName"><xsl:value-of select="'FirstAddress'"/></xsl:with-param> </xsl:call-template> <xsl:call-template name="ContactDetails"> <xsl:with-param name="data"><xsl:value-of select="RootNode/AltContactDetails"/></xsl:with-param> <xsl:with-param name="elementName"><xsl:value-of select="'SecondAddress'"/></xsl:with-param> </xsl:call-template> </xsl:template> <xsl:template name="ContactDetails"> <xsl:param name="data"></xsl:param> <xsl:param name="elementName"></xsl:param> <xsl:element name="{$elementName}"> <FirstLine> <xsl:value-of select="$data/Address/Line1"/> </FirstLine> <Town> <xsl:value-of select="$data/Address/Town"/> </Town> <PostalCode> <xsl:value-of select="$data/Address/Postcode"/> </PostalCode> </xsl:element> </xsl:template> </xsl:stylesheet> When i try to run the style sheet it's complaining to me that I need to: To use a result tree fragment in a path expression, either use exsl:node-set() or specify version 1.1 I don't want to go to version 1.1.. So does anyone know how to get the exsl:node-set() working for the above example? Or if someone knows of a better way to apply the same template to 2 different sections then that would also really help me out? Thanks Dave

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  • jQuery Map Highlight - works fine at DOM ready but failed when loaded by AJAX

    - by Michael Mao
    Hi all: This is uni assignment and I have already done some stuff. Please go to the password protected directory on : my server Enter username "uts" and password "10479475", both without quotes, into the prompt and you shall be able to see the webpage. Basically, if you hover your mouse on top of the contents in worldmap to the upperleft corner, you can see the underneath area is "highlighted" by a gray region and a red border. This is done using one jQuery plugin : at here This part works fine, however, after I use jQuery to load the specific continent map asynchronously, the newly loaded image cannot work correctly. Tested under Firebug, I can see the plugin doesn't "like" the new image cause I cannot find the canvas or other auto-generated stuff which can be founded around the worldmap. All the functionality is done in master.js, I believe you can just download a copy and check the code there. I do hope that I have followed the tutorials on the plugin's doc page, but I just cannot get through the final stage. Code used for worldmap in html: <img id="worldmap" src="./img/world.gif" alt="world.gif" width="398" height="200" class="map" usemap="#worldmap"/> <map name="worldmap"> <area class='continent' href="#" shape="poly" title="North_America" coords="1,39, 40,23, 123,13, 164,17, 159,40, 84,98, 64,111, 29,89" /> </map> Code used for worldmap in master.js //when DOM is ready, do something $(document).ready(function() { $('.map').maphilight(); //call the map highlight main function } On contrast, code used for specific continent map: //helper function to load specific continent map using AJAX function loadContinentMap(continent) { $('#continent-map-wrapper').children().remove(); //remove all children nodes first //inspiration taken from online : http://jqueryfordesigners.com/image-loading/ $('#continent-map-wrapper').append("<div id='loader' class='loading'><div>"); var img = new Image(); // wrap our new image in jQuery, then: // once the image has loaded, execute this code $(img).load(function () { $(this).hide(); // set the image hidden by default // with the holding div #loader, apply: // remove the loading class (so no background spinner), // then insert our image $('#loader').removeClass('loading').append(this); // fade our image in to create a nice effect $(this).fadeIn(); }).error(function () { // if there was an error loading the image, react accordingly // notify the user that the image could not be loaded $('#loader').removeClass('loading').append("<h1><div class='errormsg'>Loading image failed, please try again! If same error persists, please contact webmaster.</div></h1>"); }) //set a series of attributes to the img tag, these are for the map high lighting plugin. .attr('id', continent).attr('alt', '' + continent).attr('width', '576').attr('height', '300') .attr('usemap', '#city_' + continent).attr('class', 'citymap').attr('src', './img/' + continent + '.gif'); // *finally*, set the src attribute of the new image to our image //After image is loaded, apply the map highlighting plugin function again. $('.citymap').maphilight(); $('area.citymap').click(function() { alert($(this).attr('title') + ' is clicked!'); }); } Sorry about the messy code, havn't refactored it yet. I am wondering why the canvas disappers for the continent map. Did I do anything wrong. Any hint is much appreciated and thanks for any suggestion in advance!

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  • ASP.net roles and Projects

    - by Zyphrax
    EDIT - Rewrote my original question to give a bit more information Background info At my work I'm working on a ASP.Net web application for our customers. In our implementation we use technologies like Forms authentication with MembershipProviders and RoleProviders. All went well until I ran into some difficulties with configuring the roles, because the roles aren't system-wide, but related to the customer accounts and projects. I can't name our exact setup/formula, because I think our company wouldn't approve that... What's a customer / project? Our company provides management information for our customers on a yearly (or other interval) basis. In our systems a customer/contract consists of: one Account: information about the Company per Account, one or more Products: the bundle of management information we'll provide per Product, one or more Measurements: a period of time, in which we gather and report the data Extranet site setup Eventually we want all customers to be able to access their management information with our online system. The extranet consists of two sites: Company site: provides an overview of Account information and the Products Measurement site: after selecting a Measurement, detailed information on that period of time The measurement site is the most interesting part of the extranet. We will create submodules for new overviews, reports, managing and maintaining resources that are important for the research. Our Visual Studio solution consists of a number of projects. One web application named Portal for the basis. The sites and modules are virtual directories within that application (makes it easier to share MasterPages among things). What kind of roles? The following users (read: roles) will be using the system: Admins: development users :) (not customer related, full access) Employees: employees of our company (not customer related, full access) Customer SuperUser: top level managers (full access to their account/measurement) Customer ContactPerson: primary contact (full access to their measurement(s)) Customer Manager: a department manager (limited access, specific data of a measurement) What about ASP.Net users? The system will have many ASP.Net users, let's focus on the customer users: Users are not shared between Accounts SuperUser X automatically has access to all (and new) measurements User Y could be Primary contact for Measurement 1, but have no role for Measurement 2 User Y could be Primary contact for Measurement 1, but have a Manager role for Measurement 2 The department managers are many individual users (per Measurement), if Manager Z had a login for Measurement 1, we would like to use that login again if he participates in Measurement 2. URL structure These are typical urls in our application: http://host/login - the login screen http://host/project - the account/product overview screen (measurement selection) http://host/project/1000 - measurement (id:1000) details http://host/project/1000/planning - planning overview (for primary contact/superuser) http://host/project/1000/reports - report downloads (manager department X can only access report X) We will also create a document url, where you can request a specific document by it's GUID. The system will have to check if the user has rights to the document. The document is related to a Measurement, the User or specific roles have specific rights to the document. What's the problem? (finally ;)) Roles aren't enough to determine what a user is allowed to see/access/download a specific item. It's not enough to say that a certain navigation item is accessible to Managers. When the user requests Measurement 1000, we have to check that the user not only has a Manager role, but a Manager role for Measurement 1000. Summarized: How can we limit users to their accounts/measurements? (remember superusers see all measurements, some managers only specific measurements) How can we apply roles at a product/measurement level? (user X could be primarycontact for measurement 1, but just a manager for measurement 2) How can we limit manager access to the reports screen and only to their department's reports? All with the magic of asp.net classes, perhaps with a custom roleprovider implementation. Similar Stackoverflow question/problem http://stackoverflow.com/questions/1367483/asp-net-how-to-manage-users-with-different-types-of-roles

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  • How to overcome shortcomings in reporting from EAV database?

    - by David Archer
    The major shortcomings with Entity-Attribute-Value database designs in SQL all seem to be related to being able to query and report on the data efficiently and quickly. Most of the information I read on the subject warn against implementing EAV due to these problems and the commonality of querying/reporting for almost all applications. I am currently designing a system where almost all the fields necessary for data storage are not known at design/compile time and are defined by the end-user of the system. EAV seems like a good fit for this requirement but due to the problems I've read about, I am hesitant in implementing it as there are also some pretty heavy reporting requirements for this system as well. I think I've come up with a way around this but would like to pose the question to the SO community. Given that typical normalized database (OLTP) still isn't always the best option for running reports, a good practice seems to be having a "reporting" database (OLAP) where the data from the normalized database is copied to, indexed extensively, and possibly denormalized for easier querying. Could the same idea be used to work around the shortcomings of an EAV design? The main downside I see are the increased complexity of transferring the data from the EAV database to reporting as you may end up having to alter the tables in the reporting database as new fields are defined in the EAV database. But that is hardly impossible and seems to be an acceptable tradeoff for the increased flexibility given by the EAV design. This downside also exists if I use a non-SQL data store (i.e. CouchDB or similar) for the main data storage since all the standard reporting tools are expecting a SQL backend to query against. Do the issues with EAV systems mostly go away if you have a seperate reporting database for querying? EDIT: Thanks for the comments so far. One of the important things about the system I'm working on it that I'm really only talking about using EAV for one of the entities, not everything in the system. The whole gist of the system is to be able to pull data from multiple disparate sources that are not known ahead of time and crunch the data to come up with some "best known" data about a particular entity. So every "field" I'm dealing with is multi-valued and I'm also required to track history for each. The normalized design for this ends up being 1 table per field which makes querying it kind of painful anyway. Here are the table schemas and sample data I'm looking at (obviously changed from what I'm working on but I think it illustrates the point well): EAV Tables Person ------------------- - Id - Name - ------------------- - 123 - Joe Smith - ------------------- Person_Value ------------------------------------------------------------------- - PersonId - Source - Field - Value - EffectiveDate - ------------------------------------------------------------------- - 123 - CIA - HomeAddress - 123 Cherry Ln - 2010-03-26 - - 123 - DMV - HomeAddress - 561 Stoney Rd - 2010-02-15 - - 123 - FBI - HomeAddress - 676 Lancas Dr - 2010-03-01 - ------------------------------------------------------------------- Reporting Table Person_Denormalized ---------------------------------------------------------------------------------------- - Id - Name - HomeAddress - HomeAddress_Confidence - HomeAddress_EffectiveDate - ---------------------------------------------------------------------------------------- - 123 - Joe Smith - 123 Cherry Ln - 0.713 - 2010-03-26 - ---------------------------------------------------------------------------------------- Normalized Design Person ------------------- - Id - Name - ------------------- - 123 - Joe Smith - ------------------- Person_HomeAddress ------------------------------------------------------ - PersonId - Source - Value - Effective Date - ------------------------------------------------------ - 123 - CIA - 123 Cherry Ln - 2010-03-26 - - 123 - DMV - 561 Stoney Rd - 2010-02-15 - - 123 - FBI - 676 Lancas Dr - 2010-03-01 - ------------------------------------------------------ The "Confidence" field here is generated using logic that cannot be expressed easily (if at all) using SQL so my most common operation besides inserting new values will be pulling ALL data about a person for all fields so I can generate the record for the reporting table. This is actually easier in the EAV model as I can do a single query. In the normalized design, I end up having to do 1 query per field to avoid a massive cartesian product from joining them all together.

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  • Mobile App Data Syncronization

    - by Matt Rogish
    Let's say I have a mobile app that uses HTML5 SQLite DB (and/or the HTML5 key-value store). Assets (media files, PDFs, etc.) are stored locally on the mobile device. Luckily enough, the mobile device is a read-only copy of the "centralized" storage, so the mobile device won't have to propagate changes upstream. However, as the server changes assets (creates new ones, modifies existing, deletes old ones) I need to propagate those changes back to the mobile app. Assume that server changes are grouped into changesets (version number n) that contain some information (added element XYZ, deleted id = 45, etc.) and that the mobile device has limited CPU/bandwidth, so most of the processing has to take place on the server. I can think of a couple of methods to do this. All have trade-offs and at this point, I'm unsure which is the right course of action... Method 1: For change set n, store the "diff" of the current n and previous n-1. When a client with version y asks if there have been any changes, send the change sets from version y up to the current version. e.g. added item 334, contents: xxx. Deleted picture 44. Deleted PDF 11. Changed 33. added picture 99. Characteristics: Diffs take up space, although in theory would be kept small. However, all diffs must be kept around indefinitely (should a v1 app have not been updated for a year, must apply v2..v100). High latency devices (mobile apps) will incur a penalty to send lots of small files (assume cannot be zipped or tarr'd up into one file) Very few server CPU resources required, as all it does is send the client a list of files "Dumb" - if I change an item in change set 3, and change it to something else in 4, the client is going to perform both actions, even though #3 is rendered moot by #4. Or, if an asset is added in #4 and removed in #5 - the client will download a file just to delete it later. Method 2: Very similar to method 1 except on the server, do some sort of a diff between the change sets represented by the app version and server version. Package that up and send that single change set to the client. Characteristics: Client-efficient: The client only has to process one file, duplicate or irrelevant changes are stripped out. Server CPU/space intensive. The change sets must be diff'd and then written out to a file that is then sent to the client. Makes diff server scalability an issue. Possibly ways to cache the results and re-use them, but in the wild there's likely to be a lot of different versions so the diff re-use has a limit Diff algorithm is complicated. The change sets must be structured in such a way that an efficient and effective diff can be performed. Method 3: Instead of keeping diffs, write out the entire versioned asset collection to a mobile-database import file. When client requests an update, send the entire database to client and have them update their assets appropriately. Characteristics: Conceptually simple -- easy to develop and deploy Very inefficient as the client database is restored every update. If only one new thing was added, the whole database is refreshed. Server space and CPU efficient. Only the latest version DB needs kept around and the server just throws the file to the client. Others?? Thoughts? Thanks!!

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  • Does anyone have database, programming language/framework suggestions for a GUI point of sale system

    - by Jason Down
    Our company has a point of sale system with many extras, such as ordering and receiving functionality, sales and order history etc. Our main issue is that the system was not designed properly from the ground up, so it takes too long to make fixes and handle requests from our customers. Also, the current technology we are using (Progress database, Progress 4GL for the language) incurs quite a bit of licensing expenses on our customers due to mutli-user license fees for database connections etc. After a lot of discussion it is looking like we will probably start over from scratch (while maintaining the current product at least for the time being). We are looking for a couple of things: Create the system with a nice GUI front end (it is currently CHUI and the application was not built in a way that allows us to redesign the front end... no layering or separation of business logic and gui...shudder). Create the system with the ability to modularize different functionality so the product doesn't have to include all features. This would keep the cost down for our current customers that want basic functionality and a lower price tag. The bells and whistles would be available for those that would want them. Use proper design patterns to make the product easy to add or change any part at any time (i.e. change the database or change the front end without needing to rewrite the application or most of it). This is a problem today because the Progress 4GL code is directly compiled against the database. Small changes in the database requires lots of code recompiling. Our new system will be Linux based, with a possibility of a client application providing functionality from one or more windows boxes. So what I'm looking for is any suggestions on which database and/or framework or programming language(s) someone might recommend for this sort of product. Anyone that has experience in this field might be able to point us in the right direction or even have some ideas of what to avoid. We have considered .NET and SQL Express (we don't need an enterprise level DB), but that would limit us to windows (as far as I know anyway). I have heard of Mono for writing .NET code in a Linux environment, but I don't know much about it yet. We've also considered a Java and MySql based implementation. To summarize we are looking to do the following: Keep licensing costs down on the technology we will use to develop the product (Oracle, yikes! MySQL, nice.) Deliver a solution that is easily maintainable and supportable. A solution that has a component capable of running on "old" hardware through a CHUI front end. (some of our customers have 40+ terminals which would be a ton of cash in order to convert over to a PC). Suggestions would be appreciated. Thanks [UPDATE] I should note that we are currently performing a total cost analysis. This question is intended to give us a couple of "educated" options to look into to include in or analysis. Anyone who could share experiences/suggestions about client/server setups would be appreciated (not just those who have experience with point of sale systems... that would just be a bonus).

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