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• Sprinkle Some Magik on that Java Virtual Machine

  - by Jim Connors

  GE Energy, through its Smallworld subsidiary, has been providing geospatial software solutions to the utility and telco markets for over 20 years.  One of the fundamental building blocks of their technology is a dynamically-typed object oriented programming language called Magik.  Like Java, Magik source code is compiled down to bytecodes that run on a virtual machine -- in this case the Magik Virtual Machine. Throughout the years, GE has invested considerable engineering talent in the support and maintenance of this virtual machine.  At the same time vast energy and resources have been invested in the Java Virtual Machine. The question for GE has been whether to continue to make that investment on its own or to leverage massive effort provided by the Java community? Utilizing the Java Virtual Machine instead of maintaining its own virtual machine would give GE more opportunity to focus on application solutions.   At last count, there are dozens, perhaps hundreds of examples of programming languages that have been hosted atop the Java Virtual Machine.  Prior to the release of Java 7, that effort, although certainly possible, was generally less than optimal for languages like Magik because of its dynamic nature.  Java, as a statically typed language had little use for this capability.  In the quest to be a more universal virtual machine, Java 7, via JSR-292, introduced a new bytecode called invokedynamic.  In short, invokedynamic affords a more flexible method call mechanism needed by dynamic languages like Magik. With this new capability GE Energy has succeeded in hosting their Magik environment on top of the Java Virtual Machine.  So you may ask, why would GE wish to do such a thing?  The benefits are many: Competitors to GE Energy claimed that the Magik environment was proprietary.  By utilizing the Java Virtual Machine, that argument gets put to bed.  JVM development is done in open source, where contributions are made world-wide by all types of organizations and individuals. The unprecedented wealth of class libraries and applications written for the Java platform are now opened up to Magik/JVM platform as first class citizens. In addition, the Magik/JVM solution vastly increases the developer pool to include the 9 million Java developers -- the largest developer community on the planet. Applications running on the JVM showed substantial performance gains, in some cases as much as a 5x speed up over the original Magik platform. Legacy Magik applications can still run on the original platform.  They can be seamlessly migrated to run on the JVM by simply recompiling the source code. GE can now leverage the huge Java community.  Undeniably the best virtual machine ever created, hundreds if not thousands of world class developers continually improve, poke, prod and scrutinize all aspects of the Java platform.  As enhancements are made, GE automatically gains access to these. As Magik has little in the way of support for multi-threading, GE will benefit from current and future Java offerings (e.g. lambda expressions) that aim to further facilitate multi-core/multi-threaded application development. As the JVM is available for many more platforms, it broadens the reach of Magik, including the potential to run on a class devices never envisioned just a few short years ago.  For example, Java SE compatible runtime environments are available for popular embedded ARM/Intel/PowerPC configurations that could theoretically host this software too. As compared to other JVM language projects, the Magik integration differs in that it represents a serious commercial entity betting a sizable part of its business on the success of this effort.  Expect to see announcements not only from General Electric, but other organizations as they realize the benefits of utilizing the Java Virtual Machine.

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• How would you gather client's data on Google App Engine without using Datastore/Backend Instances too much?

  - by ruslan

  I'm relatively new to StackExchange and not sure if it's appropriate place to ask design question. Site gives me a hint "The question you're asking appears subjective and is likely to be closed". Please let me know. Anyway.. One of the projects I'm working on is online survey engine. It's my first big commercial project on Google App Engine. I need your advice on how to collect stats and efficiently record them in DataStore without bankrupting me. Initial requirements are: After user finishes survey client sends list of pairs [ID (int) + PercentHit (double)]. This list shows how close answers of this user match predefined answers of reference answerers (which identified by IDs). I call them "target IDs". Creator of the survey wants to see aggregated % for given IDs for last hour, particular timeframe or from the beginning of the survey. Some surveys may have thousands of target/reference answerers. So I created entity public class HitsStatsDO implements Serializable { @Id transient private Long id; transient private Long version = (long) 0; transient private Long startDate; @Parent transient private Key parent; // fake parent which contains target id @Transient int targetId; private double avgPercent; private long hitCount; } But writing HitsStatsDO for each target from each user would give a lot of data. For instance I had a survey with 3000 targets which was answered by ~4 million people within one week with 300K people taking survey in first day. Even if we assume they were answering it evenly for 24 hours it would give us ~1040 writes/second. Obviously it hits concurrent writes limit of Datastore. I decided I'll collect data for one hour and save that, that's why there are avgPercent and hitCount in HitsStatsDO. GAE instances are stateless so I had to use dynamic backend instance. There I have something like this: // Contains stats for one hour private class Shard { ReadWriteLock lock = new ReentrantReadWriteLock(); Map<Integer, HitsStatsDO> map = new HashMap<Integer, HitsStatsDO>(); // Key is target ID public void saveToDatastore(); public void updateStats(Long startDate, Map<Integer, Double> hits); } and map with shard for current hour and previous hour (which doesn't stay here for long) private HashMap<Long, Shard> shards = new HashMap<Long, Shard>(); // Key is HitsStatsDO.startDate So once per hour I dump Shard for previous hour to Datastore. Plus I have class LifetimeStats which keeps Map<Integer, HitsStatsDO> in memcached where map-key is target ID. Also in my backend shutdown hook method I dump stats for unfinished hour to Datastore. There is only one major issue here - I have only ONE backend instance :) It raises following questions on which I'd like to hear your opinion: Can I do this without using backend instance ? What if one instance is not enough ? How can I split data between multiple dynamic backend instances? It hard because I don't know how many I have because Google creates new one as load increases. I know I can launch exact number of resident backend instances. But how many ? 2, 5, 10 ? What if I have no load at all for a week. Constantly running 10 backend instances is too expensive. What do I do with data from clients while backend instance is dead/restarting? Thank you very much in advance for your thoughts.

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• How can I gather client's data on Google App Engine without using Datastore/Backend Instances too much?

  - by ruslan

  One of the projects I'm working on is online survey engine. It's my first big commercial project on Google App Engine. I need your advice on how to collect stats and efficiently record them in DataStore without bankrupting me. Initial requirements are: After user finishes survey client sends list of pairs [ID (int) + PercentHit (double)]. This list shows how close answers of this user match predefined answers of reference answerers (which identified by IDs). I call them "target IDs". Creator of the survey wants to see aggregated % for given IDs for last hour, particular timeframe or from the beginning of the survey. Some surveys may have thousands of target/reference answerers. So I created entity public class HitsStatsDO implements Serializable { @Id transient private Long id; transient private Long version = (long) 0; transient private Long startDate; @Parent transient private Key parent; // fake parent which contains target id @Transient int targetId; private double avgPercent; private long hitCount; } But writing HitsStatsDO for each target from each user would give a lot of data. For instance I had a survey with 3000 targets which was answered by ~4 million people within one week with 300K people taking survey in first day. Even if we assume they were answering it evenly for 24 hours it would give us ~1040 writes/second. Obviously it hits concurrent writes limit of Datastore. I decided I'll collect data for one hour and save that, that's why there are avgPercent and hitCount in HitsStatsDO. GAE instances are stateless so I had to use dynamic backend instance. There I have something like this: // Contains stats for one hour private class Shard { ReadWriteLock lock = new ReentrantReadWriteLock(); Map<Integer, HitsStatsDO> map = new HashMap<Integer, HitsStatsDO>(); // Key is target ID public void saveToDatastore(); public void updateStats(Long startDate, Map<Integer, Double> hits); } and map with shard for current hour and previous hour (which doesn't stay here for long) private HashMap<Long, Shard> shards = new HashMap<Long, Shard>(); // Key is HitsStatsDO.startDate So once per hour I dump Shard for previous hour to Datastore. Plus I have class LifetimeStats which keeps Map<Integer, HitsStatsDO> in memcached where map-key is target ID. Also in my backend shutdown hook method I dump stats for unfinished hour to Datastore. There is only one major issue here - I have only ONE backend instance :) It raises following questions on which I'd like to hear your opinion: Can I do this without using backend instance ? What if one instance is not enough ? How can I split data between multiple dynamic backend instances? It hard because I don't know how many I have because Google creates new one as load increases. I know I can launch exact number of resident backend instances. But how many ? 2, 5, 10 ? What if I have no load at all for a week. Constantly running 10 backend instances is too expensive. What do I do with data from clients while backend instance is dead/restarting?

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• New Sample Demonstrating the Traversing of Tree Bindings

  - by Duncan Mills

  A technique that I seem to use a fair amount, particularly in the construction of dynamic UIs is the use of a ADF Tree Binding to encode a multi-level master-detail relationship which is then expressed in the UI in some kind of looping form – usually a series of nested af:iterators, rather than the conventional tree or treetable. This technique exploits two features of the treebinding. First the fact that an treebinding can return both a collectionModel as well as a treeModel, this collectionModel can be used directly by an iterator. Secondly that the “rows” returned by the collectionModel themselves contain an attribute called .children. This attribute in turn gives access to a collection of all the children of that node which can also be iterated over. Putting this together you can represent the data encoded into a tree binding in all sorts of ways. As an example I’ve put together a very simple sample based on the HT schema and uploaded it to the ADF Sample project. It produces this UI: The important code is shown here for a Region -> Country -> Location Hierachy: <af:iterator id="i1" value="#{bindings.AllRegions.collectionModel}" var="rgn"> <af:showDetailHeader text="#{rgn.RegionName}" disclosed="true" id="sdh1"> <af:iterator id="i2" value="#{rgn.children}" var="cnty">     <af:showDetailHeader text="#{cnty.CountryName}" disclosed="true" id="sdh2">       <af:iterator id="i3" value="#{cnty.children}" var="loc">         <af:panelList id="pl1">         <af:outputText value="#{loc.City}" id="ot3"/>           </af:panelList>         </af:iterator>       </af:showDetailHeader>     </af:iterator>   </af:showDetailHeader> </af:iterator>  You can download the entire sample from here:

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• Minimum team development sizes

  - by MarkPearl

  Disclaimer - these are observations that I have had, I am not sure if this follows the philosophy of scrum, agile or whatever, but most of these insights were gained while implementing a scrum scenario. Two is a partnership, three starts a team For a while I thought that a team was anything more than one and that scrum could be effective methodology with even two people. I have recently adjusted my thinking to a scrum team being a minimum of three, so what happened to two and what do you call it? For me I consider a group of two people working together a partnership - there is value in having a partnership, but some of the dynamics and value that you get from having a team is lost with a partnership. Avoidance of a one on one confrontation The first dynamic I see missing in a partnership is the team motivation to do better and how this is delivered to individuals that are not performing. Take two highly motivated individuals and put them together and you will typically see them continue to perform. Now take a situation where you have two individuals, one performing and one not and the behaviour is totally different compared to a team of three or more individuals. With two people, if one feels the other is not performing it becomes a one on one confrontation. Most people avoid confrontations and so nothing changes. Compare this to a situation where you have three people in a team, 2 performing and 1 not the dynamic is totally different, it is no longer a personal one on one confrontation but a team concern and people seem more willing to encourage the individual not performing and express their dissatisfaction as a team if they do not improve. Avoiding the effects of Tuckman’s Group Development Theory If you are not familiar with Tuckman’s group development theory give it a read (http://en.wikipedia.org/wiki/Tuckman's_stages_of_group_development) In a nutshell with Tuckman’s theory teams go through these stages of Forming, Storming, Norming & Performing. You want your team to reach and remain in the Performing stage for as long as possible - this is where you get the most value. When you have a partnership of two and you change the individuals in the partnership you basically do a hard reset on the partnership and go back to the beginning of Tuckman’s model each time. This has a major effect on the performance of a team and what they can deliver. What I have seen is that you reduce the effects of Tuckman's theory the more individuals you have in the team (until you hit the maximum team size in which other problems kick in). While you will still experience Tuckman's theory with a team of three, the impact will be greatly reduced compared to two where it is guaranteed every time a change occurs. It's not just in the numbers, it's in the people One final comment - while the actual numbers of a team do play a role, the individuals in the team are even more important - ideally you want to keep individuals working together for an extended period. That doesn't mean that you never change the individuals in a team, or that once someone joins a team they are stuck there - there is value in an individual moving from team to team and getting cross pollination, but the period of time that an individual moves should be in month's or years, not days or weeks. Why? So why is it important to know this? Why is it important to know how a team works and what motivates them? I have been asking myself this question for a while and where I am at right now is this… the aim is to achieve the stage where the sum of the total (team) is greater than the sum of the parts (team members). This is why we form teams and why understanding how they work is a challenge and also extremely stimulating.

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• Extreme Makeover, Phone Edition: Comcasts xfinity

  Mobile Makeover For many companies the first foray into Windows Phone 7 (WP7) may be in porting their existing mobile apps. It is tempting to simply transfer existing functionality, avoiding the additional design costs. Readdressing business needs and taking advantage of the WP7 platform can reduce cost and is essential to a successful re-launch. To better understand the advantage of new development lets examine a conceptual upgrade of Comcasts existing mobile app. Before Comcast has a great mobile app that provides several key features. The ability to browse the lineup using a guide, a client for Comcast email accounts, On Demand gallery, and much more. We will leverage these and build on them using some of the incredible WP7 features.   After With the proliferation of DVRs (Digital Video Recorders) and a variety of media devices (TV, PC, Mobile) content providers are challenged to find creative ways to build their brands. Every client touch point must provide both value added services as well as opportunities for marketing and up-sale; WP7 makes it easy to focus on those opportunities. The new app is an excellent vehicle for presenting Comcasts newly rebranded TV, Voice, and Internet services. These services now fly under the banner of xfinity and have been expanded to provide the best experience for Comcast customers. The Windows Phone 7 app will increase the surface area of this service revolution.   The home menu is simplified and highlights Comcasts Triple Play: Voice, TV, and Internet. The inbox has been replaced with a messages view, and message management is handled by a WP7 hub. The hub presents emails, tweets, and IMs from Comcast and other viewers the user follows on Twitter.  The popular view orders shows based on the users viewing history and current cable package. The first show Glee is both popular and participating in a conceptual co-marketing effort, so it receives prime positioning. The second spot goes to a hit show on a premium channel, in this example HBOs The Pacific, encouraging viewers to upgrade for this premium content. The remaining spots are ordered based on viewing history and popularity. Tapping the play button moves the user to the theatre where they can watch previews or full episodes streaming from Fancast. Tapping an extra presents the user with show details as well as interactive content that may be included as part of co-marketing efforts. Co-Marketing with Dynamic Content The success of Comcasts services are tied to the success of the networks and shows it purveys, making co-marketing efforts essential. In this concept FOX is co-marketing its popular show Glee. A customized panorama is updated with the latest gleeks tweets, streaming HD episodes, and extras featuring photos and video of the cast. If WP7 apps can be dynamically extended with web hosted .xap files, including sandboxed partner experiences would enable interactive features such as the Gleek Peek, in which a viewer can select a character from a panorama to view the actors profile. This dynamic inline experience has a tailored appeal to aspiring creatives and is technically possible with Windows Phone 7.   Summary The conceptual Comcast mobile app for Windows Phone 7 highlights just a few of the incredible experiences and business opportunities that can be unlocked with this latest mobile solution. It is critical that organizations recognize and take full advantage of these new capabilities. Simply porting existing mobile applications does not leverage these powerful tools; re-examining existing applications and upgrading them to Windows Phone 7 will prove essential to the continued growth and success of your brand.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Admin Panel like Custom Framework

  - by bhuvin

  I want to Create a Framework , like Admin panel , which can rule almost all the aspects of what is shown on the frontend. For an (most basic) example: If suppose the links which are to be shown in a navigation area is passed from the server, with the order and the url , etc. The whole aim is to save the time on the tedious tasks. You can just start creating menus and start assigning pages to it. Give a url, actual files which are to be rendered (in case of static files.), in case of dynamic files, giving the file accordingly. And all this is fully server side manageable using different portlets, sort of things. So basic Roadmap is having : Areas like: Header Area - Which can contain logos, links etc. Navigation Area - Which can contains links and submenus. Content Area - Now this is where the tricky part is that that it has zones like: left, center & right. It contains Order in which it has to be displayed. So, when someday we want to change the way the articles appear on the page, we can do so easily, without any deployments. Now these zones can have n number of internal elements, like the word cloud, or the advertisement area. Footer Area: Again similar as Header Area. Currently there is a preexisting custom framework, which uses XSLT files for pulling out data from the server side. And it has the above capabilities. For example: If there's a grid it will be having a <table> tag embedded in the XSLT file. Now whatever might be the source of the data, we serialize this as XML and give it to the XSLT file and the html is derived from this and is appended to the layer in a page. The problem with this approach is: The XSLT conversion is occurring on the server side, so the server is responsible for getting the data, running XSLT transform, and append the html generated to the layer div. So, according to me, firstly this isn't the server's concern to do so. Secondly for larger applications this might be slower. Debugging isn't possible for XSLT transformation. So, whenever we face problems with data its always a bit of a trial & error method. Maintaining it is a bit of an eerie job i.e. styling changes, and other stuff. Adding dynamic values. Like JavaScript can't actually be very easily used in this. Secondly, we can't use JQuery or any other libraries with this since this is all occurring on the server. For now what I have thought about is using Templating - Javascript - JSON combination in place of XSLT, this will be offloaded to the client and the rendering will take place accordingly. This could solve the above problems and also could add mobile support for the same. Only problem which I could think of is that: It is much work and adding new portlets on the go needs to be looked into. What could be the alternatives for this? What kind of problems are there with the JavaScript approach? What are the different ways to implement the same? Are there any existing frameworks for similar usage?

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• MVVM/Presentation Model With WinForms

  - by Erik Ashepa

  Hi, I'm currently working on a brownfield application, it's written with winforms, as a preparation to use WPF in a later version, out team plans to at least use the MVVM/Presentation model, and bind it against winforms... I've explored the subject, including the posts in this site (which i love very much), when boiled down, the main advantage of wpf are : binding controls to properties in xaml. binding commands to command objects in the viewmodel. the first feature is easy to implement (in code), or with a generic control binder, which binds all the controls in the form. the second feature is a little harder to implement, but if you inherit from all your controls and add a command property (which is triggered by an internal event such as click), which is binded to a command instance in the ViewModel. The challenges I'm currently aware of are : implementing a commandmanager, (which will trigger the CanInvoke method of the commands as necessery. winforms only supports one level of databinding : datasource, datamember, wpf is much more flexible. am i missing any other major features that winforms lacks in comparison with wpf, when attempting to implement this design pattern? i sure many of you will recommend some sort of MVP pattern, but MVVM/Presentation model is the way to go for me, because I'll want future WPF support. Thanks in advance, Erik.

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• How do I get public feed from facebook without user authentication on a native/Desktop app?

  - by KronoS

  I'm looking to get publicly available facebook feeds (i.e. Google's facebook page/posts). However instead of forcing the user to sign into their own facebook app, I want to be able to access these posts. I've looked into using "App Access Tokens" however since my application is a native/Desktop app (iOS, Android, WP8/Win 8) I'm not able to do this. Is there a way to get publicly accessible feeds from facebook without user authentication? I'm using the Facebook C# SDK to access facebook. Currently I'm doing the following: dynamic tokenInfo = fb.Get( String.Format( "/oauth/access_token?client_id={0}&client_secret={1}&grant_type=client_credentials", FbController.AppId, FbController.AppSecret)); var appAccessToken = (string) tokenInfo.access_token; fb = new FacebookClient(); dynamic response = fb.Get( String.Format( "/google/posts?access_token={0}", appAccessToken)); Problem is that this only works if my application is set to "web" instead of "native/Desktop". I get the following error when running this code and classified app as native/Desktop. (OAuthException - #15) (#15) Requires session when calling from a desktop app

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• WPF / C#: Transforming coordinates from an image control to the image source

  - by Gabriel

  I'm trying to learn WPF, so here's a simple question, I hope: I have a window that contains an Image element bound to a separate data object with user-configurable Stretch property <Image Name="imageCtrl" Source="{Binding MyImage}" Stretch="{Binding ImageStretch}" /> When the user moves the mouse over the image, I would like to determine the coordinates of the mouse with respect to the original image (before stretching/cropping that occurs when it is displayed in the control), and then do something with those coordinates (update the image). I know I can add an event-handler to the MouseMove event over the Image control, but I'm not sure how best to transform the coordinates: void imageCtrl_MouseMove(object sender, MouseEventArgs e) { Point locationInControl = e.GetPosition(imageCtrl); Point locationInImage = ??? updateImage(locationInImage); } Now I know I could compare the size of Source to the ActualSize of the control, and then switch on imageCtrl.Stretch to compute the scalars and offsets on X and Y, and do the transform myself. But WPF has all the information already, and this seems like functionality that might be built-in to the WPF libraries somewhere. So I'm wondering: is there a short and sweet solution? Or do I need to write this myself? EDIT I'm appending my current, not-so-short-and-sweet solution. Its not that bad, but I'd be somewhat suprised if WPF didn't provide this functionality automatically: Point ImgControlCoordsToPixelCoords(Point locInCtrl, double imgCtrlActualWidth, double imgCtrlActualHeight) { if (ImageStretch == Stretch.None) return locInCtrl; Size renderSize = new Size(imgCtrlActualWidth, imgCtrlActualHeight); Size sourceSize = bitmap.Size; double xZoom = renderSize.Width / sourceSize.Width; double yZoom = renderSize.Height / sourceSize.Height; if (ImageStretch == Stretch.Fill) return new Point(locInCtrl.X / xZoom, locInCtrl.Y / yZoom); double zoom; if (ImageStretch == Stretch.Uniform) zoom = Math.Min(xZoom, yZoom); else // (imageCtrl.Stretch == Stretch.UniformToFill) zoom = Math.Max(xZoom, yZoom); return new Point(locInCtrl.X / zoom, locInCtrl.Y / zoom); }

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• bind a WPF datagrid to a datatable

  - by Jim Thomas

  I have used the marvelous example posted at: http://www.codeproject.com/KB/WPF/WPFDataGridExamples.aspx to bind a WPF datagrid to a datatable. The source code below compiles fine; it even runs and displays the contents of the InfoWork datatable in the wpf datagrid. Hooray! But the WPF page with the datagrid will not display in the designer. I get an incomprehensible error instead on my design page which is shown at the end of this posting. I assume the designer is having some difficulty instantiating the dataview for display in the grid. How can I fix that? XAML Code: xmlns:local="clr-namespace:InfoSeeker" <Window.Resources> <ObjectDataProvider x:Key="InfoWorkData" ObjectType="{x:Type local:InfoWorkData}" /> <ObjectDataProvider x:Key="InfoWork" ObjectInstance="{StaticResource InfoWorkData}" MethodName="GetInfoWork" /> </Window.Resources> <my:DataGrid DataContext="{Binding Source={StaticResource InfoWork}}" AutoGenerateColumns="True" ItemsSource="{Binding}" Name="dataGrid1" xmlns:my="http://schemas.microsoft.com/wpf/2008/toolkit" /> C# Code: namespace InfoSeeker { public class InfoWorkData { private InfoTableAdapters.InfoWorkTableAdapter infoAdapter; private Info infoDS; public InfoWorkData() { infoDS = new Info(); infoAdapter = new InfoTableAdapters.InfoWorkTableAdapter(); infoAdapter.Fill(infoDS.InfoWork); } public DataView GetInfoWork() { return infoDS.InfoWork.DefaultView; } } } Error shown in place of the designer page which has the grid on it: An unhandled exception has occurred: Type 'MS.Internal.Permissions.UserInitiatedNavigationPermission' in Assembly 'PresentationFramework, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' is not marked as serializable. at System.Runtime.Serialization.FormatterServices.InternalGetSerializableMembers(RuntimeType type) at System.Runtime.Serialization.FormatterServices.GetSerializableMembers(Type type, StreamingContext context) at System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitMemberInfo() at System.Runtime.Serialization.Formatters.Binary.WriteObjectInfo.InitSerialize(Object obj, ISurrogateSelector surrogateSelector, StreamingContext context, SerObjectInfoInit serObjectInfoInit, IFormatterConverter converter, ObjectWriter objectWriter) ...At:Ms.Internal.Designer.DesignerPane.LoadDesignerView()

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• Telerik RadGridView problem

  - by Polaris

  I am using Telerik RadGridView in my project. I want to show image in column. GridViewImageColumn col1 = new GridViewImageColumn(); col1.Width = 100; col1.DataMemberBinding = new Binding("id"); col1.Header = "PhotoByConverter"; col1.DataMemberBinding.Converter = new ThumbnailConverter(); grid.Columns.Add(col1); GridViewImageColumn col2 = new GridViewImageColumn(); col2.Width = 100; col2.DataMemberBinding = new Binding("firstName"); col2.Header = "Person name"; col2.DataMemberBinding.Converter = new ThumbnailConverter(); grid.Columns.Add(col2); Grid.ItemsSource=DataTable; First column not wokrs but second works fine. I use Converter for image shown below public class ThumbnailConverter : IValueConverter { public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { IEnumerable<thumbNail> result = from n in thumbnails where n.personID == value.ToString() select n; if (result != null && result.First().thumbnail != null) { return result.First().thumbnail.file; } else { return null; } } public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { throw new Exception("The method or operation is not implemented."); } } I found by id thumbnail of person and set it like data for GridViewImageColumn. I checked with Debuger conveter works properly. I can't undesrtand why it doesn't work. Any ideas?

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• Why do I get a DependencyProperty.UnsetValue when converting a value in a MultiBinding?

  - by eskerber

  I have an extremely simple IMultiValueConverter that simply OR's two values. In the example below, I want to invert the first value using an equally simple boolean inverter. <MultiBinding Converter="{StaticResource multiBoolToVis}"> <Binding Path="ConditionA" Converter="{StaticResource boolInverter}"/> <Binding Path="ConditionB"/> </MultiBinding> public class BoolInverterConverter : IValueConverter { #region IValueConverter Members public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { if (value is bool) { return !((bool)value); } return null; } public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { throw new NotImplementedException(); } #endregion } When I include the boolInverter, the first value in the MultiValueConverter becomes a "DependencyProperty.UnsetValue". There are no problems when I do not use the converter (other than not the logic I am aiming for, of course). Am I missing something? Stepping through the debugger shows that the InverseBoolConverter is properly inverting the value I pass it, but that value is then not being 'sent' to the MultiValueConverter.

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• MVVM Prism Nested Regions Can't Find Child Regions

  - by Garry Clark

  I have a Menu (Telerik RadMenu) that has nested regions defined in the Shell. In my modules I will register the modules menu or toolbar items with these regions. Everything works fine for the root regions, but when I try and add something to a child region, such as the File region on the Menu, I get the error "The exception message was: The region manager does not contain the FileMenuRegion region." However like I said if I change this code regionManager.Regions[RegionNames.FileMenuRegion].Add(menuItem); to this regionManager.Regions[RegionNames.MainMenuRegion].Add(menuItem); everything works fine. Below is the XAML for my menu so you can see the region names and how they are constructed. Any help would greatly be appreciated as this is bewildering and driving me crazy. Menu <telerikNavigation:RadMenu x:Name="menuMain" DockPanel.Dock="Top" prismrgn:RegionManager.RegionName="{x:Static i:RegionNames.MainMenuRegion}" telerik:StyleManager.Theme="{Binding Source={StaticResource settings}, Path=Default.CurrentTheme}"> <telerikNavigation:RadMenuItem Header="{x:Static p:Resources.File}" prismrgn:RegionManager.RegionName="{x:Static i:RegionNames.FileMenuRegion}"> <telerikNavigation:RadMenuItem Header="{x:Static p:Resources.Exit}" Command="{Binding ExitCommand}"> <telerikNavigation:RadMenuItem.Icon> <Image Source="../Resources/Close.png" Stretch="None" /> </telerikNavigation:RadMenuItem.Icon> </telerikNavigation:RadMenuItem> </telerikNavigation:RadMenuItem> </telerikNavigation:RadMenu>

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• WPF ObservableCollection CollectionView.CurrentChanged not firing.

  - by EL

  Hi folks, I have a problem with one of my ICollectionViews. The ICollectionView's CurrentChanged event i not firing. Please see my code below. XAML: <!-- Publication --> <TextBlock Name="tbkPublication" Text="{x:Static abConst:Print.tbkPublicationText}" Grid.Row="0" Grid.Column="0" Margin="3" ></TextBlock> <ComboBox Grid.Column="1" Grid.Row="0" Margin="3" Name="cmbPublication" BorderThickness="1" ItemsSource="{Binding Path=EnterpriseList}" DisplayMemberPath="Name" SelectedValuePath="Value" SelectedIndex="0" IsSynchronizedWithCurrentItem="True" /> <!-- Distribution Area Region --> <TextBlock Name="tbkDistributionArea" Text="{x:Static abConst:Print.tbkDistributionAreaText}" Grid.Row="1" Grid.Column="0" Margin="3" ></TextBlock> <ComboBox Grid.Column="1" Grid.Row="1" Margin="3" Name="cmbDistributionArea" BorderThickness="1" ItemsSource="{Binding Path=ZonesList}" DisplayMemberPath="Name" SelectedValuePath="Value" SelectedIndex="0" IsSynchronizedWithCurrentItem="True" /> AND C# (ViewModel) #region Properties public ObservableCollection<GenericNameValuePair<int, string>> EnterpriseList { get { return _abEnterpriseList; } set { _abEnterpriseList = value; } } public ObservableCollection<GenericNameValuePair<int, string>> ZonesList { get { return _abZonesList; } set { _abZonesList = value; } } #endregion private void InitCollections() { _collectionViewEnterprise = CollectionViewSource.GetDefaultView(EnterpriseList); _collectionViewZone = CollectionViewSource.GetDefaultView(ZonesList); //Replace if(_collectionViewEnterprise == null) throw new NullReferenceException("Enterprise collectionView is null."); if (_collectionViewZone == null) throw new NullReferenceException("Zone collectionView is null."); _collectionViewEnterprise.CurrentChanged += new EventHandler(OnCollectionViewEnterpriseCurrentChanged); _collectionViewZone.CurrentChanged += new EventHandler(OnCollectionViewZoneCurrentChanged); } Please help. Thanks in advance.

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• Scope of StaticResource within a WPF ResourceDictionary

  - by Nicolas Webb

  I have a WPF ResourceDictionary with the following TextBlock: <TextBlock Visibility="{Binding Converter={StaticResource MyBoolProp ResourceKey=BoolToVis}}"> </TextBlock> The ResourceDictionary is included in App.xaml under MergedDictionaries: <Application.Resources> <ResourceDictionary> <ResourceDictionary.MergedDictionaries> <ResourceDictionary Source="MyResourceDictionary.xaml"/> Within the App.xaml I have defined the BoolToVis converter (again, under Application.Resources) <BooleanToVisibilityConverter x:Key="BoolToVis" /> When I start my app up - I get the following XamlParseException: "Provide value on 'System.Windows.Markup.StaticResourceHolder' threw an exception." The InnerException is: "Cannot find resource named 'BoolToVis'. Resource names are case sensitive." I'm able to refer to this converter directly with App.xaml (in fact, it's another TextBlock) and within other UserControls with no problems. This particular bit of code also worked fine under the .NET 4.0 RC (and Beta2). This error only started happening when I upgraded to the .NET 4.0 RTM. I'm able to work around it by declaring another BooleanToVisibilityConverter within MyResourceDictionary.xaml and referring to it like so: <TextBlock Visibility="{Binding Converter={StaticResource MyBoolProp ResourceKey=BoolToVis2}}"> </TextBlock> Any reason why I should need to do this?

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• Do SEO-friendly URLs really affect a page's ranking?

  - by Lee Harold

  SEO-friendly URLs are all the rage these days. But do they actually have a meaningful impact on a page's ranking in Google and other search engines? If so, why? If not, why not? (Note that I would absolutely agree that SEO-friendly URLs are nicer to use for human beings. My question is whether they actually make a difference to the ranking algorithms.) Update: As it turns out, the Google post that endorphine points to here has caused tremendous confusion in the SEO community. For a sampling of the discussion, see here, here, and here. Part of the problem is that the Google post is addressing the worst case where URL rewriting is done poorly and so you'd be better off sticking with a dynamic URL rather than a mangled static "SEO-friendly" URL. There's no question dynamic URLs can be crawled by Google and can achieve high rankings. Maybe it would be easier to reframe the question more concretely: given 2 otherwise equivalent pages, which will rank higher for the search "do seo friendly urls really affect page ranking"? A) http://stackoverflow.com/questions/505793/do-seo-friendly-urls-really-affect-a-pages-ranking or B) http://stackoverflow.com?question=505793 (a fake URL for comparison only)

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• Alternative to FindAncestor RelativeSource in Silverlight 4 to bind to a property of the page

  - by TimothyP

  Hi, FindAncestor RelativeSource only supports 'Self' and 'TemplatedParent', but I have to bind the width of a popup to the width of the page. Giving the page a name causes problems because sometimes it will throw exceptions saying a control with that name is already present in the visual tree. <Popup IsOpen="True" Width="{Binding ElementName=BordPage, Path=Width}" Height="{Binding ElementName=BordPage, Path=Height}"> Background information: I'm using a SL4 navigation based application here. BordPage is a navigation page, which I'm using multiple times within the application. So giving it a name in the page itself is not really a good idea, but I don't know how else I can bind to the width and height of the page. What I'm trying to do is have a black border (with opacity 0.8) cover the entire screen, (including the controls of the MainPage). Then on top of that I want to display some other controls. Since the application is touch controlled, providing the user with a ComboBox to select a value doesn't really work wel. Instead I want to show this black overlay window with a listbox taking up most of the screen so the user can simply touch the value he wants with a single click. Update: I just realized I can use the ChildWindow class to do this. But my original question remains.

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• WCF - The maximum nametable character count quota (16384) has been exceeded while reading XML data.

  - by Jankhana

  I'm having a WCF Service that uses wsHttpBinding. The server configuration is as follows : <bindings> <wsHttpBinding> <binding name="wsHttpBinding" maxBufferPoolSize="2147483647" maxReceivedMessageSize="2147483647"> <readerQuotas maxDepth="2147483647" maxStringContentLength="2147483647" maxArrayLength="2147483647" maxBytesPerRead="2147483647" maxNameTableCharCount="2147483647" /> <security mode="None"> <transport clientCredentialType="Windows" proxyCredentialType="None" realm="" /> <message clientCredentialType="Windows" negotiateServiceCredential="true" algorithmSuite="Default" establishSecurityContext="true" /> </security> </binding> </wsHttpBinding> </bindings> At the client side I'm including the Service reference of the WCF-Service. It works great if I have limited functions say 90 Operation Contract in my IService but if add one more OperationContract than I'm unable to Update the Service reference nor i'm able to add that service reference. In this article it's mentioned that by changing those config files(i.e devenv.exe.config, WcfTestClient.exe.config and SvcUtil.exe.config) it will work but even including those bindings in those config files still that error pops up saying There was an error downloading 'http://10.0.3.112/MyService/Service1.svc/mex'. The request failed with HTTP status 400: Bad Request. Metadata contains a reference that cannot be resolved: 'http://10.0.3.112/MyService/Service1.svc/mex'. There is an error in XML document (1, 89549). The maximum nametable character count quota (16384) has been exceeded while reading XML data. The nametable is a data structure used to store strings encountered during XML processing - long XML documents with non-repeating element names, attribute names and attribute values may trigger this quota. This quota may be increased by changing the MaxNameTableCharCount property on the XmlDictionaryReaderQuotas object used when creating the XML reader. Line 1, position 89549. If the service is defined in the current solution, try building the solution and adding the service reference again. Any idea how to solve this????

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• WPF 4.0 Custom panel won't show dynamically added controls in VS 2010 Designer

  - by Matt Ruwe

  I have a custom panel control that I'm trying to dynamically add controls within. When I run the application the static and dynamically added controls show up perfectly, but the dynamic controls do not appear within the visual studio designer. Only the controls placed declaratively in the XAML appear. I'm currently adding the dynamic control in the CreateUIElementCollection override, but I've also tried this in the constructor without success. Public Class CustomPanel1 Inherits Panel Public Sub New() End Sub Protected Overrides Function MeasureOverride(ByVal availableSize As System.Windows.Size) As System.Windows.Size Dim returnValue As New Size(0, 0) For Each child As UIElement In Children child.Measure(availableSize) returnValue.Width = Math.Max(returnValue.Width, child.DesiredSize.Width) returnValue.Height = Math.Max(returnValue.Height, child.DesiredSize.Height) Next returnValue.Width = If(Double.IsPositiveInfinity(availableSize.Width), returnValue.Width, availableSize.Width) returnValue.Height = If(Double.IsPositiveInfinity(availableSize.Height), returnValue.Height, availableSize.Height) Return returnValue End Function Protected Overrides Function ArrangeOverride(ByVal finalSize As System.Windows.Size) As System.Windows.Size Dim currentHeight As Integer For Each child As UIElement In Children child.Arrange(New Rect(0, currentHeight, child.DesiredSize.Width, child.DesiredSize.Height)) currentHeight += child.DesiredSize.Height Next Return finalSize End Function Protected Overrides Function CreateUIElementCollection(ByVal logicalParent As System.Windows.FrameworkElement) As System.Windows.Controls.UIElementCollection Dim returnValue As UIElementCollection = MyBase.CreateUIElementCollection(logicalParent) returnValue.Add(New TextBlock With {.Text = "Hello, World!"}) Return returnValue End Function Protected Overrides Sub OnPropertyChanged(ByVal e As System.Windows.DependencyPropertyChangedEventArgs) MyBase.OnPropertyChanged(e) End Sub End Class And my usage of this custom panel <Window x:Class="MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:CustomPanel" Title="MainWindow" Height="364" Width="434"> <local:CustomPanel1> <CheckBox /> <RadioButton /> </local:CustomPanel1> </Window>

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• DomainDataSource DataPager with silverlight 3 DataGrid & .Net RIA Services

  - by Dennis Ward

  I have a simple datagrid example with silverlight 3, and am populating it with the .NET ria services using a DomainDataSource along with a DataPager declaratively (nothing in the code-behind), and am experiencing this problem: The LoadSize is 30, and the Page size is 15, and when the page is loaded, the 1st and 2nd page appear correctly, but when I go beyond the 2nd page, nothing shows up in the grid. This used to work in the silverlight 3 beta with the Mix 2009 preview of .NET Ria services, and I've got a really simple example and have verified that the Service on the web project gets called to load a new batch, but the grid doesn't show any data. Can anyone shed any light as to why grid displays data only for the initial load of data and not subsequent batches from the pager? Here's my xaml: <riaControls:DomainDataSource x:Name="ArtistSource" QueryName="GetArtist" AutoLoad="True" LoadSize="30" PageSize="15"> <riaControls:DomainDataSource.DomainContext> <domain:AdminContext /> </riaControls:DomainDataSource.DomainContext> </riaControls:DomainDataSource> <data:DataGrid Grid.Row="1" x:Name="ArtistDataGrid" ItemsSource="{Binding Data, ElementName=ArtistSource}"> </data:DataGrid> <StackPanel Grid.Row="2"> <data:DataPager Source="{Binding Data, ElementName=ArtistSource}" /> </StackPanel>

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• Silverlight DatePicker in DataGrid: Enter does not submit

  - by queen3

  I have DataGrid with DataGridTemplateColumn which has DatePicker as editing element: <data:DataGridTemplateColumn Header="Due date" CanUserSort="False" > <data:DataGridTemplateColumn.CellTemplate> <DataTemplate> <TextBlock Text="{Binding EndDateFormatted}" /> </DataTemplate> </data:DataGridTemplateColumn.CellTemplate> <data:DataGridTemplateColumn.CellEditingTemplate> <DataTemplate> <controls:DatePicker SelectedDate="{Binding EndDate, Mode=TwoWay}" /> </DataTemplate> </data:DataGridTemplateColumn.CellEditingTemplate> </data:DataGridTemplateColumn> The problem is that Enter key does not work at all when in textbox editing mode - just does nothing. Selecting date from dropdown panel works. Also, Tab does not keep value (reset to previous one), but with help of this I can fix it. But I don't know how to make Enter to accept value and preferably move to next cell. I also tried third-party date picker, no changes - same issues with Tab and Enter. Seems like a DataGrid issue. I use Silverlight 3.

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• Making flexible C# code in MVC2 for Stored Procedures

  - by cc0

  Thanks to Darin Dimitrov's suggestion I got a big step further in understanding good MVC code, but I'm having some problems making it flexible. I implemented Darin's suggested solution, and it works perfectly for single controllers. However I'm having some trouble implementing it with some flexibility. What I'm looking for is this; To be able to make dynamic column names in json Instead of using "Column1: 'value', ..." and "Column2: 'value', ..." inside the json, I'd like to use for example "id: 'value', ..." and "place: 'value' ..." for one stored procedure, and "animal" and "type" in another (inside the json format). To be able to make dynamic amounts of columns dependent on which stored procedure is called Some stored procedures I'll want to read more than 2 rows from, is there a smart way of accomplishing that? To be able to make numeric (floats and integers) rows from the database be presented inside the json without quotes Like this (name and age); { Column1: "John", Column2: 53 }, I would be very grateful for any feedback and suggestions / code examples I can get here. Even imperfect ones.

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• WCF service with Factory attribute on .svc is not working on web server (IIS6), but is locally using

  - by Jessica

  I am working on implementing a non web.config approach of WCF services using the factory attribute on the .svc file per Rick Strahl's blog post: Factory="System.ServiceModel.Activation.WebScriptServiceHostFactory" Locally, I am running IIS7 in Visual Studio 2008 and have no problem, but when I deploy to my web server (currently running IIS6), I am getting an authentication error in the event log: Exception: System.ServiceModel.ServiceActivationException: The service '/Services/ResourcesService.svc' cannot be activated due to an exception during compilation. The exception message is: IIS specified authentication schemes 'IntegratedWindowsAuthentication, Anonymous', but the binding only supports specification of exactly one authentication scheme. Valid authentication schemes are Digest, Negotiate, NTLM, Basic, or Anonymous. Change the IIS settings so that only a single authentication scheme is used.. --- System.InvalidOperationException: IIS specified authentication schemes 'IntegratedWindowsAuthentication, Anonymous', but the binding only supports specification of exactly one authentication scheme. Valid authentication schemes are Digest, Negotiate, NTLM, Basic, or Anonymous. Change the IIS settings so that only a single authentication scheme is used. at System.ServiceModel.Web.WebServiceHost.SetBindingCredentialBasedOnHostedEnvironment(ServiceEndpoint serviceEndpoint, AuthenticationSchemes supportedSchemes) at System.ServiceModel.Web.WebServiceHost.AddAutomaticWebHttpBindingEndpoints(ServiceHost host, IDictionary`2 implementedContracts, String multipleContractsErrorMessage) at System.ServiceModel.WebScriptServiceHost.OnOpening() at System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout) at System.ServiceModel.Channels.CommunicationObject.Open() at System.ServiceModel.ServiceHostingEnvironment.HostingManager.ActivateService(String normalizedVirtualPath) at System.ServiceModel.ServiceHostingEnvironment.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath) After doing some Googling, I changed my authentication settings on the .svc folder within my project (on the server) to only anonymous authentication, but it did not work. I still get web service failed on the calls. IIS7 by default only had anonymous. I do not have any entries in my web.config for the services (I stripped them out per this pattern). I am using a nant script to deploy the website to the server and use this also locally to verify the script was not causing the issue. Any known issue with this? IIS 6 not able to handle?

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• WPF RelativeSource FindAncestor doesn't work outside of the Control.Resources context?

  - by sker

  I have this VisualBrush resource I took from some site and I apply it with triggers to a TextBox. <VisualBrush x:Key="HelpBrush" TileMode="None" Opacity="0.4" Stretch="None" AlignmentX="Left"> <VisualBrush.Visual> <TextBlock FontStyle="Italic" Text="{Binding Path=Tag, RelativeSource={RelativeSource AncestorType={x:Type Control}, AncestorLevel=1}}"/> </VisualBrush.Visual> </VisualBrush> <Style x:Key="DefaultText" TargetType="TextBox"> <Style.Triggers> <Trigger Property="Text" Value="{x:Null}"> <Setter Property="Background" Value="{StaticResource HelpBrush}"/> </Trigger> <Trigger Property="Text" Value=""> <Setter Property="Background" Value="{StaticResource HelpBrush}"/> </Trigger> </Style.Triggers> </Style> If I place both the VisualBrush and the Style inside the TextBox.Resources tag in XAML, it works fine. But if I take it out and place it in the Window.Resources or a merged dictionary, it stops working. The problem is the Binding, it doesn't find the ancestor TextBox for some reason. I already tried removing AncestorLevel and using AncestorType={x:Type TextBox} - it doesn't work. Any ideas?

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