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• Data Virtualization: Federated and Hybrid

  - by Krishnamoorthy

  Data becomes useful when it can be leveraged at the right time. Not only enterprises application stores operate on large volume, velocity and variety of data. Mobile and social computing are in the need of operating in foresaid data. Replicating and transferring large swaths of data is one challenge faced in the field of data integration. However, smaller chunks of data aggregated from a variety of sources presents and even more interesting challenge in the industry. Over the past few decades, technology trends focused on best user experience, operating systems, high performance computing, high performance web sites, analysis of warehouse data, service oriented architecture, social computing, cloud computing, and big data. Operating on the ‘dark data’ becomes mandatory in the future technology trend, although, no solution can make dark data useful data in a single day. Useful data can be quantified by the facts of contextual, personalized and on time delivery. In most cases, data from a single source may not be complete the picture. Data has to be combined and computed from various sources, where data may be captured as hybrid data, meaning the combination of structured and unstructured data. Since related data is often found across disparate sources, effectively integrating these sources determines how useful this data ultimately becomes. Technology trends in 2013 are expected to focus on big data and private cloud. Consumers are not merely interested in where data is located or how data is retrieved and computed. Consumers are interested in how quick and how the data can be leveraged. In many cases, data virtualization is the right solution, and is expected to play a foundational role for SOA, Cloud integration, and Big Data. The Oracle Data Integration portfolio includes a data virtualization product called ODSI (Oracle Data Service Integrator). Unlike other data virtualization solutions, ODSI can perform both read and write operations on federated/hybrid data (RDBMS, Webservices,  delimited file and XML). The ODSI Engine is built on XQuery, hence ODSI user can perform computations on data either using XQuery or SQL. Built in data and query caching features, which reduces latency in repetitive calls. Rightly positioning ODSI, can results in a highly scalable model, reducing spend on additional hardware infrastructure.

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• Combobox binding with different types

  - by George Evjen

  Binding to comboboxes in Silverlight has been an adventure the past couple of days. In our framework at ArchitectNow we use LookupGroups and LookupValues. In our database we would have a LookupGroup of NBA Teams for example. The group would be called NBATeams, we get the LookupGroupID and then get the values from the LookupValues table. So we would end up with a list of all 30+ teams. Our lookup values entity has a display text(string), value(string), IsActive and some other fields. With our applications we load all this information into the system when the user is logging in or right after they login. So in cache we have a list of groups and values that we can get at whenever we want to. We get this information in our framework simply by creating an observable collection of type LookupValue. To get a list of these values into our property all we have to do is. var NBATeams = AppContext.Current.LookupSerivce.GetLookupValues(“NBATeams”); Our combobox then is bound like this. (We use telerik components in most if not all our projects) <telerik:RadComboBox ItemsSource="{Binding NBATeams}”></telerik:RadComboBox> This should give you a list in your combobox. We also set up another property in our ViewModel that is a just single object of NBATeams  - “SelectedNBATeam” Our selectedItem in our combobox would look like, we would set this to a two way binding since we are sending data back. SelectedItem={Binding SelectedNBATeam, mode=TwoWay}” This is all pretty straight forward and we use this pattern throughout all our applications. What do you do though when you have a combobox in a ItemsControl or ListBox? Here we have a list of NBA Teams that are a string that are being brought back from the database. We cant have the selected item be our LookupValue because the data is a string and its being bound in an ItemsControl. In the example above we would just have the combobox in a form. Here though we have it in a ItemsControl, where there is no selected item from the initial ItemsSource. In order to get the selected item to be displayed in the combobox you have to convert the LookupValue to a string. Then instead of using SelectedItem in the combobox use SelectedValue. To convert the LookupValue we do this. Create an observable collection of strings public ObservableCollection<string> NBATeams { get; set;} Then convert your lookups to strings var NBATeams = new ObservableCollection<string>(AppContext.Current.LookupService.GetLookupValues(“NBATeams”).Select(x => x.DisplayText)); This will give us a list of strings and our selected value should be bound to the NBATeams property in our ItemsSource in our ItemsControl. SelectedValue={Binding NBATeam, mode=TwoWay}”

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• How to retrive message list from p2p

  - by cre-johnny07

  Hello friends I have a messaging system that uses p2p. Each peer has a incoming message list and a outgoing message list. What I need to do is whenever a new peer will join the mesh he will get the all the incoming messages from other peers and add those into it's own incoming message list. Now I know when I get the other peer info from I can ask them to give their own list to me. But I'm not finding the way how..? Any suggestion on this or help would be highly appreciated. I'm giving my code below. Thanking in Advance Johnny #region Instance Fields private string strOrigin = ""; //the chat member name private string m_Member; //the channel instance where we execute our service methods against private IServerChannel m_participant; //the instance context which in this case is our window since it is the service host private InstanceContext m_site; //our binding transport for the p2p mesh private NetPeerTcpBinding m_binding; //the factory to create our chat channel private ChannelFactory<IServerChannel> m_channelFactory; //an interface provided by the channel exposing events to indicate //when we have connected or disconnected from the mesh private IOnlineStatus o_statusHandler; //a generic delegate to execute a thread against that accepts no args private delegate void NoArgDelegate(); //an object to hold user details private IUserService userService; //an Observable Collection of object to get all the Application Instance Details in databas ObservableCollection<AppLoginInstance> appLoginInstances; // an Observable Collection of object to get all Incoming Messages types ObservableCollection<MessageType> inComingMessageTypes; // an Observable Collection of object to get all Outgoing Messages ObservableCollection<PDCL.ERP.DataModels.Message> outGoingMessages; // an Observable Collection of object to get all Incoming Messages ObservableCollection<PDCL.ERP.DataModels.Message> inComingMessages; //an Event Aggregator to publish event for other modules to subscribe private readonly IEventAggregator eventAggregator; /// <summary> /// an IUnityCOntainer to get the container /// </summary> private IUnityContainer container; private RefreshConnectionStatus refreshConnectionStatus; private RefreshConnectionStatusEventArgs args; private ReplyRequestMessage replyMessageRequest; private ReplyRequestMessageEventArgs eventsArgs; #endregion public P2pMessageService(IUserService UserService, IEventAggregator EventAggregator, IUnityContainer container) { userService = UserService; this.container = container; appLoginInstances = new ObservableCollection<AppLoginInstance>(); inComingMessageTypes = new ObservableCollection<MessageType>(); inComingMessages = new ObservableCollection<PDCL.ERP.DataModels.Message>(); outGoingMessages = new ObservableCollection<PDCL.ERP.DataModels.Message>(); this.args = new RefreshConnectionStatusEventArgs(); this.eventsArgs = new ReplyRequestMessageEventArgs(); this.eventAggregator = EventAggregator; this.refreshConnectionStatus = this.eventAggregator.GetEvent<RefreshConnectionStatus>(); this.replyMessageRequest = this.eventAggregator.GetEvent<ReplyRequestMessage>(); } #region IOnlineStatus Event Handlers void ostat_Offline(object sender, EventArgs e) { // we could update a status bar or animate an icon to //indicate to the user they have disconnected from the mesh //currently i don't have a "disconnect" button but adding it //should be trivial if you understand the rest of this code } void ostat_Online(object sender, EventArgs e) { try { m_participant.Join(userService.AppInstance); } catch (Exception Ex) { Logger.Exception(Ex, Ex.TargetSite.Name + ": " + Ex.TargetSite + ": " + Ex.Message); } } #endregion #region IServer Members //this method gets called from a background thread to //connect the service client to the p2p mesh specified //by the binding info in the app.config public void ConnectToMesh() { try { m_site = new InstanceContext(this); //use the binding from the app.config with default settings m_binding = new NetPeerTcpBinding("P2PMessageBinding"); m_channelFactory = new DuplexChannelFactory<IServerChannel>(m_site, "P2PMessageEndPoint"); m_participant = m_channelFactory.CreateChannel(); o_statusHandler = m_participant.GetProperty<IOnlineStatus>(); o_statusHandler.Online += new EventHandler(ostat_Online); o_statusHandler.Offline += new EventHandler(ostat_Offline); //m_participant.InitializeMesh(); //this.appLoginInstances.Add(this.userService.AppInstance); BackgroundWorkerHelper.DoWork<object>(() => { //this is an empty unhandled method on the service interface. //why? because for some reason p2p clients don't try to connect to the mesh //until the first service method call. so to facilitate connecting i call this method //to get the ball rolling. m_participant.InitializeMesh(); //SynchronizeMessage(this.inComingMessages); return new object(); }, arg => { }); this.appLoginInstances.Add(this.userService.AppInstance); } catch (Exception Ex) { Logger.Exception(Ex, Ex.TargetSite.Name + ": " + Ex.TargetSite + ": " + Ex.Message); } } public void Join(AppLoginInstance obj) { try { // Adding Instance to the PeerList if (appLoginInstances.SingleOrDefault(a => a.InstanceId == obj.InstanceId)==null) { appLoginInstances.Add(obj); this.refreshConnectionStatus.Publish(new RefreshConnectionStatusEventArgs() { Status = m_channelFactory.State }); } //this will retrieve any new members that have joined before the current user m_participant.SynchronizeMemberList(userService.AppInstance); } catch(Exception Ex) { Logger.Exception(Ex,Ex.TargetSite.Name + ": " + Ex.TargetSite + ": " + Ex.Message); } } /// <summary> /// Synchronizes member list /// </summary> /// <param name="obj">The AppLoginInstance Param</param> public void SynchronizeMemberList(AppLoginInstance obj) { //as member names come in we simply disregard duplicates and //add them to the member list, this way we can retrieve a list //of members already in the chatroom when we enter at any time. //again, since this is just an example this is the simplified //way to do things. the correct way would be to retrieve a list //of peernames and retrieve the metadata from each one which would //tell us what the member name is and add it. we would want to check //this list when we join the mesh to make sure our member name doesn't //conflict with someone else try { if (appLoginInstances.SingleOrDefault(a => a.InstanceId == obj.InstanceId) == null) { appLoginInstances.Add(obj); } } catch (Exception Ex) { Logger.Exception(Ex, Ex.TargetSite.Name + ": " + Ex.TargetSite + ": " + Ex.Message); } } /// <summary> /// This methos broadcasts the mesasge to all peers. /// </summary> /// <param name="msg">The whole message which is to be broadcasted</param> /// <param name="securityLevels"> Level of security</param> public void BroadCastMsg(PDCL.ERP.DataModels.Message msg, List<string> securityLevels) { try { foreach (string s in securityLevels) { if (this.userService.IsInRole(s)) { if (this.inComingMessages.Count == 0 && msg.CreatedByApp != this.userService.AppInstanceId) { this.inComingMessages.Add(msg); } else if (this.inComingMessages.SingleOrDefault(a => a.MessageId == msg.MessageId) == null && msg.CreatedByApp != this.userService.AppInstanceId) { this.inComingMessages.Add(msg); } } } } catch (Exception Ex) { Logger.Exception(Ex, Ex.TargetSite.Name + ": " + Ex.TargetSite + ": " + Ex.Message); } } /// <summary> /// /// </summary> /// <param name="msg">The Message to denyed</param> public void BroadCastReplyMsg(PDCL.ERP.DataModels.Message msg) { try { //if (this.inComingMessages.SingleOrDefault(a => a.MessageId == msg.MessageId) != null) //{ this.replyMessageRequest.Publish(new ReplyRequestMessageEventArgs() { Message = msg }); this.inComingMessages.Remove(this.inComingMessages.SingleOrDefault(o => o.MessageId == msg.MessageId)); //} } catch (Exception ex) { Logger.Exception(ex, ex.TargetSite.Name + ": " + ex.TargetSite + ": " + ex.Message); } } //again we need to sync the worker thread with the UI thread via Dispatcher public void Whisper(string Member, string MemberTo, string Message) { } public void InitializeMesh() { //do nothing } public void Leave(AppLoginInstance obj) { if (this.appLoginInstances.SingleOrDefault(a => a.InstanceId == obj.InstanceId) != null) { this.appLoginInstances.Remove(this.appLoginInstances.Single(a => a.InstanceId == obj.InstanceId)); } } //public void SynchronizeRemoveMemberList(AppLoginInstance obj) //{ // if (appLoginInstances.SingleOrDefault(a => a.InstanceId == obj.InstanceId) != null) // { // appLoginInstances.Remove(obj); // } //} #endregion

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• StoreGeneratedPattern T4 EntityFramework concern

  - by LoganWolfer

  Hi everyone, Here's the situation : I use SQL Server 2008 R2, SQL Replication, Visual Studio 2010, EntityFramework 4, C# 4. The course-of-action from our DBA is to use a rowguid column for SQL Replication to work with our setup. These columns need to have a StoreGeneratedPattern property set to Computed on every one of these columns. The problem : Every time the T4 template regenerate our EDMX (ADO.NET Entity Data Model) file (for example, when we update it from our database), I need to go manually in the EDMX XML file to add this property to every one of them. It has to go from this : <Property Name="rowguid" Type="uniqueidentifier" Nullable="false" /> To this : <Property Name="rowguid" Type="uniqueidentifier" Nullable="false" StoreGeneratedPattern="Computed"/> The solution : I'm trying to find a way to customize an ADO.NET EntityObject Generator T4 file to generate a StoreGeneratedPattern="Computed" to every rowguid that I have. I'm fairly new to T4, I only did customization to AddView and AddController T4 templates for ASP.NET MVC 2, like List.tt for example. I've looked through the EF T4 file, and I can't seem to find through this monster where I could do that (and how). My best guess is somewhere in this part of the file, line 544 to 618 of the original ADO.NET EntityObject Generator T4 file : //////// //////// Write PrimitiveType Properties. //////// private void WritePrimitiveTypeProperty(EdmProperty primitiveProperty, CodeGenerationTools code) { MetadataTools ef = new MetadataTools(this); #> /// <summary> /// <#=SummaryComment(primitiveProperty)#> /// </summary><#=LongDescriptionCommentElement(primitiveProperty, 1)#> [EdmScalarPropertyAttribute(EntityKeyProperty=<#=code.CreateLiteral(ef.IsKey(primitiveProperty))#>, IsNullable=<#=code.CreateLiteral(ef.IsNullable(primitiveProperty))#>)] [DataMemberAttribute()] <#=code.SpaceAfter(NewModifier(primitiveProperty))#><#=Accessibility.ForProperty(primitiveProperty)#> <#=code.Escape(primitiveProperty.TypeUsage)#> <#=code.Escape(primitiveProperty)#> { <#=code.SpaceAfter(Accessibility.ForGetter(primitiveProperty))#>get { <#+ if (ef.ClrType(primitiveProperty.TypeUsage) == typeof(byte[])) { #> return StructuralObject.GetValidValue(<#=code.FieldName(primitiveProperty)#>); <#+ } else { #> return <#=code.FieldName(primitiveProperty)#>; <#+ } #> } <#=code.SpaceAfter(Accessibility.ForSetter((primitiveProperty)))#>set { <#+ if (ef.IsKey(primitiveProperty)) { if (ef.ClrType(primitiveProperty.TypeUsage) == typeof(byte[])) { #> if (!StructuralObject.BinaryEquals(<#=code.FieldName(primitiveProperty)#>, value)) <#+ } else { #> if (<#=code.FieldName(primitiveProperty)#> != value) <#+ } #> { <#+ PushIndent(CodeRegion.GetIndent(1)); } #> <#=ChangingMethodName(primitiveProperty)#>(value); ReportPropertyChanging("<#=primitiveProperty.Name#>"); <#=code.FieldName(primitiveProperty)#> = StructuralObject.SetValidValue(value<#=OptionalNullableParameterForSetValidValue(primitiveProperty, code)#>); ReportPropertyChanged("<#=primitiveProperty.Name#>"); <#=ChangedMethodName(primitiveProperty)#>(); <#+ if (ef.IsKey(primitiveProperty)) { PopIndent(); #> } <#+ } #> } } private <#=code.Escape(primitiveProperty.TypeUsage)#> <#=code.FieldName(primitiveProperty)#><#=code.StringBefore(" = ", code.CreateLiteral(primitiveProperty.DefaultValue))#>; partial void <#=ChangingMethodName(primitiveProperty)#>(<#=code.Escape(primitiveProperty.TypeUsage)#> value); partial void <#=ChangedMethodName(primitiveProperty)#>(); <#+ } Any help would be appreciated. Thanks in advance. EDIT : Didn't find answer to this problem yet, if anyone have ideas to automate this, would really be appreciated.

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• Introduction to LinqPad Driver for StreamInsight 2.1

  - by Roman Schindlauer

  We are announcing the availability of the LinqPad driver for StreamInsight 2.1. The purpose of this blog post is to offer a quick introduction into the new features that we added to the StreamInsight LinqPad driver. We’ll show you how to connect to a remote server, how to inspect the entities present of that server, how to compose on top of them and how to manage their lifetime. Installing the driver Info on how to install the driver can be found in an earlier blog post here. Establishing connections As you click on the “Add Connection” link in the left pane you will notice that now it’s possible to build the data context automatically. The new driver appears as an option in the upper list, and if you pick it you will open a connection dialog that lets you connect to a remote StreamInsight server. The connection dialog lets you specify the address of the remote server. You will notice that it’s possible to pick up the binding information from the configuration file of the LinqPad application (which is normally in the same folder as LinqPad.exe and is called LinqPad.exe.config). In order for the context to be generated you need to pick an application from the server. The control is editable hence you can create a new application if you don’t want to make changes to an existing application. If you choose a new application name you will be prompted for confirmation before this gets created. Once you click OK the connection is created and you can start issuing queries against the remote server. If there’s any connectivity error the connection is marked with a red X and you can see the error message informing you what went wrong (i.e., the remote server could not be reached etc.). The context for remote servers Let’s take a look at what happens after we are connected successfully. Every LinqPad query runs inside a context – think of it as a class that wraps all the code that you’re writing. If you’re connecting to a live server the context will contain the following: The application object itself. All entities present in this application (sources, sinks, subjects and processes). The picture below shows a snapshot of the left pane of LinqPad after a successful connection. Every entity on the server has a different icon which will allow users to figure out its purpose. You will also notice that some entities have a string in parentheses following the name. It should be interpreted as such: the first name is the name of the property of the context class and the second name is the name of the entity as it exists on the server. Not all valid entity names are valid identifier names so in cases where we had to make a transformation you see both. Note also that as you hover over the entities you get IntelliSense with their types – more on that later. Remoting is not supported As you play with the entities exposed by the context you will notice that you can’t read and write directly to/from them. If for instance you’re trying to dump the content of an entity you will get an error message telling you that in the current version remoting is not supported. This is because the entity lives on the remote server and dumping its content means reading the events produced by this entity into the local process. ObservableSource.Dump(); Will yield the following error: Reading from a remote 'System.Reactive.Linq.IQbservable`1[System.Int32]' is not supported. Use the 'Microsoft.ComplexEventProcessing.Linq.RemoteProvider.Bind' method to read from the source using a remote observer. This basically tells you that you can call the Bind() method to direct the output of this source to a sink that has to be defined on the remote machine as well. You can’t bring the results to the LinqPad window unless you write code specifically for that. Compose queries You may ask – what's the purpose of all that? After all the same information is present in the EventFlowDebugger, why bother with showing it in LinqPad? First of all, What gets exposed in LinqPad is not what you see in the debugger. In LinqPad we have a property on the context class for every entity that lives on the server. Because LinqPad offers IntelliSense we in fact have much more information about the entity, and more importantly we can compose with that entity very easily. For example, let’s say that this code creates an entity: using (var server = Server.Connect(...)) {     var a = server.CreateApplication("WhiteFish");     var src = a         .DefineObservable<int>(() => Observable.Range(0, 3))         .Deploy("ObservableSource"); If later we want to compose with the source we have to fetch it and then we can bind something to     a.GetObservable<int>("ObservableSource)").Bind(... This means that we had to know a bunch of things about this: that it’s a source, that it’s an observable, it produces a result with payload Int32 and it’s named “ObservableSource”. Only the second and last bits of information are present in the debugger, by the way. As you type in the query window you see that all the entities are present, you get IntelliSense support for them and it’s much easier to make sense of what’s available. Let’s look at a scenario where composition is plausible. With the new programming model it’s possible to create “cold” sources that are parameterized. There was a way to accomplish that even in the previous version by passing parameters to the adapters, but this time it’s much more elegant because the expression declares what parameters are required. Say that we hover the mouse over the ThrottledSource source – we will see that its type is Func<int, int, IQbservable<int>> - this in effect means that we need to pass two int parameters before we can get a source that produces events, and the type for those events is int – in the particular case of my example I had the source produce a range of integers and the two parameters were the start and end of the range. So we see how a developer can create a source that is not running yet. Then someone else (e.g. an administrator) can pass whatever parameters appropriate and run the process. Proxy Types Here’s an interesting scenario – what if someone created a source on a server but they forgot to tell you what type they used. Worse yet, they might have used an anonymous type and even though they can refer to it by name you can’t figure out how to use that type. Let’s walk through an example that shows how you can compose against types you don’t need to have the definition of. This is how we can create a source that returns an anonymous type: Application.DefineObservable(() => Observable.Range(1, 10).Select(i => new { I = i })).Deploy("O1"); Now if we refresh the connection we can see the new source named O1 appear in the list. But what’s more important is that we now have a type to work with. So we can compose a query that refers to the anonymous type. var threshold = new StreamInsightDynamicDriver.TypeProxies.AnonymousType1_0<int>(5); var filter = from i in O1              where i > threshold              select i; filter.Deploy("O2"); You will notice that the anonymous type defined with this statement: new { I = i } can now be manipulated by a client that does not have access to it because the LinqPad driver has generated another type in its stead, named StreamInsightDynamicDriver.TypeProxies.AnonymousType1_0. This type has all the properties and fields of the type defined on the server, except in this case we can instantiate values and use it to compose more queries. It is worth noting that the same thing works for types that are not anonymous – the test is if the LinqPad driver can resolve the type or not. If it’s not possible then a new type will be generated that approximates the type that exists on the server. Control metadata In addition to composing processes on top of the existing entities we can do other useful things. We can delete them – nothing new here as we simply access the entities through the Entities collection of the application class. Here is where having their real name in parentheses comes handy. There’s another way to find out what’s behind a property – dump its expression. The first line in the output tells us what’s the name of the entity used to build this property in the context. Runtime information So let’s create a process to see what happens. We can bind a source to a sink and run the resulting process. If you right click on the connection you can refresh it and see the process present in the list of entities. Then you can drag the process to the query window and see that you can have access to process object in the Processes collection of the application. You can then manipulate the process (delete it, read its diagnostic view etc.). Regards, The StreamInsight Team

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• Introduction to LinqPad Driver for StreamInsight 2.1

  - by Roman Schindlauer

  We are announcing the availability of the LinqPad driver for StreamInsight 2.1. The purpose of this blog post is to offer a quick introduction into the new features that we added to the StreamInsight LinqPad driver. We’ll show you how to connect to a remote server, how to inspect the entities present of that server, how to compose on top of them and how to manage their lifetime. Installing the driver Info on how to install the driver can be found in an earlier blog post here. Establishing connections As you click on the “Add Connection” link in the left pane you will notice that now it’s possible to build the data context automatically. The new driver appears as an option in the upper list, and if you pick it you will open a connection dialog that lets you connect to a remote StreamInsight server. The connection dialog lets you specify the address of the remote server. You will notice that it’s possible to pick up the binding information from the configuration file of the LinqPad application (which is normally in the same folder as LinqPad.exe and is called LinqPad.exe.config). In order for the context to be generated you need to pick an application from the server. The control is editable hence you can create a new application if you don’t want to make changes to an existing application. If you choose a new application name you will be prompted for confirmation before this gets created. Once you click OK the connection is created and you can start issuing queries against the remote server. If there’s any connectivity error the connection is marked with a red X and you can see the error message informing you what went wrong (i.e., the remote server could not be reached etc.). The context for remote servers Let’s take a look at what happens after we are connected successfully. Every LinqPad query runs inside a context – think of it as a class that wraps all the code that you’re writing. If you’re connecting to a live server the context will contain the following: The application object itself. All entities present in this application (sources, sinks, subjects and processes). The picture below shows a snapshot of the left pane of LinqPad after a successful connection. Every entity on the server has a different icon which will allow users to figure out its purpose. You will also notice that some entities have a string in parentheses following the name. It should be interpreted as such: the first name is the name of the property of the context class and the second name is the name of the entity as it exists on the server. Not all valid entity names are valid identifier names so in cases where we had to make a transformation you see both. Note also that as you hover over the entities you get IntelliSense with their types – more on that later. Remoting is not supported As you play with the entities exposed by the context you will notice that you can’t read and write directly to/from them. If for instance you’re trying to dump the content of an entity you will get an error message telling you that in the current version remoting is not supported. This is because the entity lives on the remote server and dumping its content means reading the events produced by this entity into the local process. ObservableSource.Dump(); Will yield the following error: Reading from a remote 'System.Reactive.Linq.IQbservable`1[System.Int32]' is not supported. Use the 'Microsoft.ComplexEventProcessing.Linq.RemoteProvider.Bind' method to read from the source using a remote observer. This basically tells you that you can call the Bind() method to direct the output of this source to a sink that has to be defined on the remote machine as well. You can’t bring the results to the LinqPad window unless you write code specifically for that. Compose queries You may ask – what's the purpose of all that? After all the same information is present in the EventFlowDebugger, why bother with showing it in LinqPad? First of all, What gets exposed in LinqPad is not what you see in the debugger. In LinqPad we have a property on the context class for every entity that lives on the server. Because LinqPad offers IntelliSense we in fact have much more information about the entity, and more importantly we can compose with that entity very easily. For example, let’s say that this code creates an entity: using (var server = Server.Connect(...)) {     var a = server.CreateApplication("WhiteFish");     var src = a         .DefineObservable<int>(() => Observable.Range(0, 3))         .Deploy("ObservableSource"); If later we want to compose with the source we have to fetch it and then we can bind something to     a.GetObservable<int>("ObservableSource)").Bind(... This means that we had to know a bunch of things about this: that it’s a source, that it’s an observable, it produces a result with payload Int32 and it’s named “ObservableSource”. Only the second and last bits of information are present in the debugger, by the way. As you type in the query window you see that all the entities are present, you get IntelliSense support for them and it’s much easier to make sense of what’s available. Let’s look at a scenario where composition is plausible. With the new programming model it’s possible to create “cold” sources that are parameterized. There was a way to accomplish that even in the previous version by passing parameters to the adapters, but this time it’s much more elegant because the expression declares what parameters are required. Say that we hover the mouse over the ThrottledSource source – we will see that its type is Func<int, int, IQbservable<int>> - this in effect means that we need to pass two int parameters before we can get a source that produces events, and the type for those events is int – in the particular case of my example I had the source produce a range of integers and the two parameters were the start and end of the range. So we see how a developer can create a source that is not running yet. Then someone else (e.g. an administrator) can pass whatever parameters appropriate and run the process. Proxy Types Here’s an interesting scenario – what if someone created a source on a server but they forgot to tell you what type they used. Worse yet, they might have used an anonymous type and even though they can refer to it by name you can’t figure out how to use that type. Let’s walk through an example that shows how you can compose against types you don’t need to have the definition of. This is how we can create a source that returns an anonymous type: Application.DefineObservable(() => Observable.Range(1, 10).Select(i => new { I = i })).Deploy("O1"); Now if we refresh the connection we can see the new source named O1 appear in the list. But what’s more important is that we now have a type to work with. So we can compose a query that refers to the anonymous type. var threshold = new StreamInsightDynamicDriver.TypeProxies.AnonymousType1_0<int>(5); var filter = from i in O1              where i > threshold              select i; filter.Deploy("O2"); You will notice that the anonymous type defined with this statement: new { I = i } can now be manipulated by a client that does not have access to it because the LinqPad driver has generated another type in its stead, named StreamInsightDynamicDriver.TypeProxies.AnonymousType1_0. This type has all the properties and fields of the type defined on the server, except in this case we can instantiate values and use it to compose more queries. It is worth noting that the same thing works for types that are not anonymous – the test is if the LinqPad driver can resolve the type or not. If it’s not possible then a new type will be generated that approximates the type that exists on the server. Control metadata In addition to composing processes on top of the existing entities we can do other useful things. We can delete them – nothing new here as we simply access the entities through the Entities collection of the application class. Here is where having their real name in parentheses comes handy. There’s another way to find out what’s behind a property – dump its expression. The first line in the output tells us what’s the name of the entity used to build this property in the context. Runtime information So let’s create a process to see what happens. We can bind a source to a sink and run the resulting process. If you right click on the connection you can refresh it and see the process present in the list of entities. Then you can drag the process to the query window and see that you can have access to process object in the Processes collection of the application. You can then manipulate the process (delete it, read its diagnostic view etc.). Regards, The StreamInsight Team

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• JavaOne Tutorial Report - JavaFX 2 – A Java Developer’s Guide

  - by Janice J. Heiss

  Oracle Java Technology Evangelist Stephen Chin and Independent Consultant Peter Pilgrim presented a tutorial session intended to help developers get a handle on JavaFX 2. Stephen Chin, a Java Champion, is co-author of the Pro JavaFX Platform 2, while Java Champion Peter Pilgrim is an independent consultant who works out of London.NightHacking with Stephen ChinBefore discussing the tutorial, a note about Chin’s “NightHacking Tour,” wherein from 10/29/12 to 11/11/12, he will be traveling across Europe via motorcycle stopping at JUGs and interviewing Java developers and offering live video streaming of the journey. As he says, “Along the way, I will visit user groups, interviewing interesting folks, and hack on open source projects. The last stop will be the Devoxx conference in Belgium.”It’s a dirty job but someone’s got to do it. His trip will take him from the UK through the Netherlands, Germany, Switzerland, Italy, France, and finally to Devoxx in Belgium. He has interviews lined up with Ben Evans, Trisha Gee, Stephen Coulebourne, Martijn Verburg, Simon Ritter, Bert Ertman, Tony Epple, Adam Bien, Michael Hutterman, Sven Reimers, Andres Almiray, Gerrit Grunewald, Bertrand Boetzmann, Luc Duponcheel, Stephen Janssen, Cheryl Miller, and Andrew Phillips. If you expect to be in Chin’s vicinity at the end of October and in early November, by all means get in touch with him at his site and add your perspective. The more the merrier! Taking the JavaFX PlungeNow to the business at hand. The “JavaFX 2 – A Java Developer’s Guide” tutorial introduced Java developers to the JavaFX 2 platform from the perspective of seasoned Java developers. It demonstrated the breadth of the JavaFX APIs through examples that are built out in the course of the session in an effort to present the basic requirements in using JavaFX to build rich internet applications. Chin began with a quote from Oracle’s Christopher Oliver, the creator of F3, the original version of JavaFX, on the importance of GUIs:“At the end of the day, on the one hand we have computer systems, and on the other, people. Connecting them together, and allowing people to interact with computer systems in a compelling way, requires graphical user interfaces.”Chin explained that JavaFX is about producing an immersive application experience that involves cross-platform animation, video and charting. It can integrate Java, JavaScript and HTML in the same application. The new graphics stack takes advantage of hardware acceleration for 2D and 3D applications. In addition, we can integrate Swing applications using JFXPanel.He reminded attendees that they were building JavaFX apps using pure Java APIs that included builders for declarative construction; in addition, alternative languages can be used for simpler UI creation. In addition, developers can call upon alternative languages such as GroovyFX, ScalaFX and Visage, if they want simpler UI creation. He presented the fundamentals of JavaFX 2.0: properties, lists and binding and then explored primitive, object and FX list collection properties. Properties in JavaFX are observable, lazy and type safe. He then provided an example of property declaration in code.  Pilgrim and Chin explained the architectural structure of JavaFX 2 and its basic properties:JavaFX 2.0 properties – Primitive, Object, and FX List Collection properties. * Primitive Properties* Object Properties* FX List Collection Properties* Properties are:– Observable– Lazy– Type SafeChin and Pilgrim then took attendees through several participatory demos and got deep into the weeds of the code for the two-hour session. At the end, everyone knew a lot more about the inner workings of JavaFX 2.0.

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• Reactive Extensions vs FileSystemWatcher

  - by Joel Mueller

  One of the things that has long bugged me about the FileSystemWatcher is the way it fires multiple events for a single logical change to a file. I know why it happens, but I don't want to have to care - I just want to reparse the file once, not 4-6 times in a row. Ideally, there would be an event that only fires when a given file is done changing, rather than every step along the way. Over the years I've come up with various solutions to this problem, of varying degrees of ugliness. I thought Reactive Extensions would be the ultimate solution, but there's something I'm not doing right, and I'm hoping someone can point out my mistake. I have an extension method: public static IObservable<IEvent<FileSystemEventArgs>> GetChanged(this FileSystemWatcher that) { return Observable.FromEvent<FileSystemEventArgs>(that, "Changed"); } Ultimately, I would like to get one event per filename, within a given time period - so that four events in a row with a single filename are reduced to one event, but I don't lose anything if multiple files are modified at the same time. BufferWithTime sounds like the ideal solution. var bufferedChange = watcher.GetChanged() .Select(e => e.EventArgs.FullPath) .BufferWithTime(TimeSpan.FromSeconds(1)) .Where(e => e.Count > 0) .Select(e => e.Distinct()); When I subscribe to this observable, a single change to a monitored file triggers my subscription method four times in a row, which rather defeats the purpose. If I remove the Distinct() call, I see that each of the four calls contains two identical events - so there is some buffering going on. Increasing the TimeSpan passed to BufferWithTime seems to have no effect - I went as high as 20 seconds without any change in behavior. This is my first foray into Rx, so I'm probably missing something obvious. Am I doing it wrong? Is there a better approach? Thanks for any suggestions...

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• Time flies like an arrow demo in WinForms

  - by Benjol

  Looking at the Reactive Extensions for javascript demo on Jeff Van Gogh's blog, I thought I'd give it a try in C#/Winforms, but it doesn't seem to work so well. I just threw this into the constructor of a form (with the Rx framework installed and referenced): Observable.Context = SynchronizationContext.Current; var mousemove = Observable.FromEvent<MouseEventArgs>(this, "MouseMove"); var message = "Time flies like an arrow".ToCharArray(); for(int i = 0; i < message.Length; i++) { var l = new Label() { Text = message[i].ToString(), AutoSize = true, TextAlign = ContentAlignment.MiddleCenter }; int closure = i; mousemove .Delay(closure * 150) .Subscribe(e => { l.Left = e.EventArgs.X + closure * 15 + 10; l.Top = e.EventArgs.Y; //Debug.WriteLine(l.Text); }); Controls.Add(l); } When I move the mouse, the letters seem to get moved in a random order, and if I uncomment the Debug line, I see multiple events for the same letter... Any ideas? I've tried Throttle, but it doesn't seem to make any difference. Am I just asking too much of WinForms to move all those labels around? (Cross posted on Rx Forum)

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• Java invokeAndWait of C# Action Delegate

  - by ikurtz

  the issue i mentioned in this post is actually happening because of cross threading GUI issues (i hope). could you help me with Java version of action delegate please? in C# it is done as this inline: this.Invoke(new Action(delegate() {...})); how is this achived in Java? thank you. public class processChatMessage implements Observer { public void update(Observable o, Object obj) { System.out.println("class class class" + obj.getClass()); if (obj instanceof String){ String msg = (String)obj; formatChatHeader(chatHeader.Away, msg); jlStatusBar.setText("Message Received"); // Show chat form setVisibility(); } } } processChatMessage is invoked by a separate thread triggered by receiving new data from a remote node. and i think the error is being produced as it trying to update GUI controls. do you think this is the reason? i ask because im new to Java and C#, but this is what is going on i think. SOLUTION: public class processChatMessage implements Observer { public void update(Observable o, Object obj) { if (obj instanceof String){ final String msg = (String)obj; try { SwingUtilities.invokeAndWait(new Runnable( ) { public void run( ) { formatChatHeader(chatHeader.Away, msg); jlStatusBar.setText("Message Received"); setVisibility(); } }); } catch (InterruptedException e){ } catch (InvocationTargetException e){ } } } }

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• Where to find algorithms for standard math functions?

  - by dsimcha

  I'm looking to submit a patch to the D programming language standard library that will allow much of std.math to be evaluated at compile time using the compile-time function evaluation facilities of the language. Compile-time function evaluation has several limitations, the most important ones being: You can't use assembly language. You can't call C code or code for which the source is otherwise unavailable. Several std.math functions violate these and compile-time versions need to be written. Where can I get information on good algorithms for computing things such as logarithms, exponents, powers, and trig functions? I prefer just high level descriptions of algorithms to actual code, for two reasons: To avoid legal ambiguity and the need to make my code look "different enough" from the source to make sure I own the copyright. I want simple, portable algorithms. I don't care about micro-optimization as long as they're at least asymptotically efficient. Edit: D's compile time function evaluation model allows floating point results computed at compile time to differ from those computed at runtime anyhow, so I don't care if my compile-time algorithms don't give exactly the same result as the runtime version as long as they aren't less accurate to a practically significant extent.

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• Using multiple aggregate functions in an (ANSI) SQL statement

  - by morpheous

  I have aggregate functions foo(), foobar(), fredstats(), barneystats() I want to create a domain specific query language (DSQL) above my DB, to facilitate using a domain language to query the DB. The 'language' comprises of algebraic expressions (or more specifically SQL like criteria) which I use to generate (ANSI) SQL statements which are sent to the db engine. The following lines are examples of what the language statements will look like, and hopefully, it will help further clarify the concept: **Example 1** DQL statement: foobar('yellow') between 1 and 3 and fredstats('weight') > 42 Translation: fetch all rows in an underlying table where computed values for aggregate function foobar() is between 1 and 3 AND computed value for AGG FUNC fredstats() is greater than 42 **Example 2** DQL statement: fredstats('weight') < barneystats('weight') AND foo('fighter') in (9,10,11) AND foobar('green') <> 42 Translation: Fetch all rows where the specified criteria matches **Example 3** DQL statement: foobar('green') / foobar('red') <> 42 Translation: Fetch all rows where the specified criteria matches **Example 4** DQL statement: foobar('green') - foobar('red') >= 42 Translation: Fetch all rows where the specified criteria matches Given the following information: The table upon which the queries above are being executed is called 'tbl' table 'tbl' has the following structure (id int, name varchar(32), weight float) The result set returns only the tbl.id, tbl.name and the names of the aggregate functions as columns in the result set - so for example the foobar() AGG FUNC column will be called foobar in the result set. So for example, the first DQL query will return a result set with the following columns: id, name, foobar, fredstats Given the above, my questions then are: What would be the underlying SQL required for Example1 ? What would be the underlying SQL required for Example3 ? Given an algebraic equation comprising of AGGREGATE functions, Is there a way of generalizing the algorithm needed to generate the required ANSI SQL statement(s)? I am using PostgreSQL as the db, but I would prefer to use ANSI SQL wherever possible.

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• Proving that the distance values extracted in Dijkstra's algorithm is non-decreasing?

  - by Gail

  I'm reviewing my old algorithms notes and have come across this proof. It was from an assignment I had and I got it correct, but I feel that the proof certainly lacks. The question is to prove that the distance values taken from the priority queue in Dijkstra's algorithm is a non-decreasing sequence. My proof goes as follows: Proof by contradiction. Fist, assume that we pull a vertex from Q with d-value 'i'. Next time, we pull a vertex with d-value 'j'. When we pulled i, we have finalised our d-value and computed the shortest-path from the start vertex, s, to i. Since we have positive edge weights, it is impossible for our d-values to shrink as we add vertices to our path. If after pulling i from Q, we pull j with a smaller d-value, we may not have a shortest path to i, since we may be able to reach i through j. However, we have already computed the shortest path to i. We did not check a possible path. We no longer have a guaranteed path. Contradiction.

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• Combining aggregate functions in an (ANSI) SQL statement

  - by morpheous

  I have aggregate functions foo(), foobar(), fredstats(), barneystats() I want to create a domain specific query language (DSQL) above my DB, to facilitate using using a domain language to query the DB. The 'language' comprises of boolean expressions (or more specifically SQL like criteria) which I then 'translate' back into pure (ANSI) SQL and send to the underlying Db. The following lines are examples of what the language statements will look like, and hopefully, it will help further clarify the concept: **Example 1** DQL statement: foobar('yellow') between 1 and 3 and fredstats('weight') > 42 Translation: fetch all rows in an underlying table where computed values for aggregate function foobar() is between 1 and 3 AND computed value for AGG FUNC fredstats() is greater than 42 **Example 2** DQL statement: fredstats('weight') < barneystats('weight') AND foo('fighter') in (9,10,11) AND foobar('green') <> 42 Translation: Fetch all rows where the specified criteria matches **Example 3** DQL statement: foobar('green') / foobar('red') <> 42 Translation: Fetch all rows where the specified criteria matches **Example 4** DQL statement: foobar('green') - foobar('red') >= 42 Translation: Fetch all rows where the specified criteria matches Given the following information: The table upon which the queries above are being executed is called 'tbl' table 'tbl' has the following structure (id int, name varchar(32), weight float) The result set returns only the tbl.id, tbl.name and the names of the aggregate functions as columns in the result set - so for example the foobar() AGG FUNC column will be called foobar in the result set. So for example, the first DQL query will return a result set with the following columns: id, name, foobar, fredstats Given the above, my questions then are: What would be the underlying SQL required for Example1 ? What would be the underlying SQL required for Example3 ? Given an algebraic equation comprising of AGGREGATE functions, Is there a way of generalizing the algorithm needed to generate the required ANSI SQL statement(s)? I am using PostgreSQL as the db, but I would prefer to use ANSI SQL wherever possible.

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• State Animation on ListBox ItemTemplate

  - by Peanut

  I have a listbox which reads from Observable collection, and is ItemTemplate'ed: <DataTemplate x:Key="DataTemplate1"> <Grid x:Name="grid" Height="47.333" Width="577" Opacity="0.495"> <Image HorizontalAlignment="Left" Margin="10.668,8,0,8" Width="34" Source="{Binding ImageLocation}"/> <TextBlock Margin="56,8,172.334,8" TextWrapping="Wrap" Text="{Binding ApplicationName}" FontSize="21.333"/> <Grid x:Name="grid1" HorizontalAlignment="Right" Margin="0,10.003,-0.009,11.33" Width="26" Opacity="0" RenderTransformOrigin="0.5,0.5"> <Image HorizontalAlignment="Stretch" Margin="0" Source="image/downloads.png" Stretch="Fill" MouseDown="Image_MouseDown" /> </Grid> </Grid> </DataTemplate> <ListBox x:Name="searchlist" Margin="8" ItemTemplate="{DynamicResource DataTemplate1}" ItemsSource="{Binding SearchResults}" SelectionChanged="searchlist_SelectionChanged" ItemContainerStyle="{DynamicResource ListBoxItemStyle1}" /> In general, my question is "What is the easiest way to do Animation on Particular Items in this listbox As they are selected? Basically the image inside the "grid1" will be setting its opacity to 1, slowly. I would prefer to use states, but I do not know of any way to just tell blend and xaml to "When a selected item is changed, change the image opacity to 1 over a period of .3 seconds". Infact, I have been doing this in the .cs file using the VisualStateManager. Also, there is another issue. When the selected index is changed, we goto the CS file and look at SelectedItem. SelectedItem returns an instance of the Object in which it was bound to (The object inside the observable collection), and NOT an instance of the DataTemplate/ListItem etc. So how am I able to pull the correct image out of this list? State animation with VisualStateManager I can handle fine if its just normal things, but when it comes to generated listboxes' items, I'm lost. Thanks

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• Is there "good" PRNG generating values without hidden state?

  - by actual

  I need some good pseudo random number generator that can be computed like a pure function from its previous output without any state hiding. Under "good" I mean: I must be able to parametrize generator in such way that running it for 2^n iterations with any parameters should cover all or almost all values between 0 and 2^n - 1, where n is the number of bits in output value. Combined generator output of n + p bits must cover all or almost all values between 0 and 2^(n + p) - 1 if I run it for 2^n iterations for every possible combination of its parameters, where p is the number of bits in parameters. For example, LCG can be computed like a pure function and it can meet first condition, but it can not meet second one. Say, we have 32-bit generator, m = 2^32 and it is constant, our p = 64 (two 32-bit parameters a and c), n + p = 96, so we must peek data by three ints from output to meet second condition. Unfortunately, condition can not be meet because of strictly alternating sequence of odd and even ints in output. To overcome this, hidden state must be introduced, but that makes function not pure and breaks first condition (period become much longer). Am I wanting too much?

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• Writing an auto-memoizer in Scheme. Help with macro and a wrapper.

  - by kunjaan

  I am facing a couple of problems while writing an auto-memoizer in Scheme. I have a working memoizer function, which creats a hash table and checks if the value is already computed. If it has been computed before then it returns the value else it calls the function. (define (memoizer fun) (let ((a-table (make-hash))) (?(n) (define false-if-fail (?() #f)) (let ((return-val (hash-ref a-table n false-if-fail))) (if return-val return-val (begin (hash-set! a-table n (fun n)) (hash-ref a-table n))))))) Now I want to create a memoize-wrapper function like this: (define (memoize-wrapper function) (set! function (memoizer function))) And hopefully create a macro called def-memo which defines the function with the memoize-wrapper. eg. the macro could expand to (memoizer (define function-name arguments body ...) or something like that. So that I should be able to do : (def-memo (factorial n) (cond ((= n 1) 1) (else (* n (factorial (- n 1)))))) which should create a memoized version of the factorial instead of the normal slow one. My problem is that the The memoize-wrapper is not working properly, it doesnt call the memoized function but the original function. I have no idea how to write a define inside of the macro. How do I make sure that I can get variable lenght arguments and variable length body? How do I then define the function and wrap it around with the memoizer? Thanks a lot.

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• why does this knockout method receive a form element instead of the object its nested in?

  - by ladookie

  I have this HTML: <ul class="chat_list" data-bind="foreach: chats"> <li> <div class="chat_response" data-bind="visible: CommentList().length == 0"> <form data-bind="submit: $root.addComment"> <input class="comment_field" placeholder="Comment…" data-bind="value: NewCommentText" /> </form> </div> </li> </ul> and this JavaScript: function ChatListViewModel(chats) { // var self = this; self.chats = ko.observableArray(ko.utils.arrayMap(chats, function (chat) { return { CourseItemDescription: chat.CourseItemDescription, CommentList: ko.observableArray(chat.CommentList), CourseItemID: chat.CourseItemID, UserName: chat.UserName, ChatGroupNumber: chat.ChatGroupNumber, ChatCount: chat.ChatCount, NewCommentText: ko.observable("") }; })); self.newChatText = ko.observable(); self.addComment = function (chat) { var newComment = { CourseItemDescription: chat.NewCommentText(), ParentCourseItemID: chat.CourseItemID, CourseID: $.CourseLogic.dataitem.CourseID, AccountID: $.CourseLogic.dataitem.AccountID, SystemObjectID: $.CourseLogic.dataitem.CommentSystemObjectID, SystemObjectName: "Comments", UserName: chat.UserName }; chat.CommentList.push(newComment); chat.NewCommentText(""); }; } ko.applyBindings(new ChatListViewModel(initialData)); When I go into the debugger it shows that the chat parameter of the addComment() function is a form element instead of a chat object. Why is this happening?

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• DataTrigger not reevaluating after property changes

  - by frozen

  I have a listbox which has its itemssource (this is done in the code behind on as the window is created) databound to an observable collection. The List box then has the following data template assigned against the items: usercontrol.xaml ... <ListBox x:Name="communicatorListPhoneControls" ItemContainerStyle="{StaticResource templateForCalls}"/> ... app.xaml ... <Style x:Key="templateForCalls" TargetType="{x:Type ListBoxItem}"> <Setter Property="ContentTemplate" Value="{StaticResource templateRinging}"/> <Style.Triggers> <DataTrigger Binding="{Binding Path=hasBeenAnswered}" Value="True"> <Setter Property="ContentTemplate" Value="{StaticResource templateAnswered}"/> </DataTrigger> </Style.Triggers> </Style> ... When the observable collection is updated with an object, this appears in the listbox with the correct initial datatemplate, however when the "hasBeenAnswered" property is set to true (when debugging i can see the collection is correct) the datatrigger does not re-evaluate and then update the listbox to use the correct data template. I have implemented the INotifyPropertyChanged Event in my object, and if in the template i bind to a value, i can see the value update. Its just that the datatrigger will not re-evaluate and change to the correct template. I know the datatrigger binding is correct because if i close the window and open it again, it will correctly apply the second datatemplate, because the "hasBeenAnswered" is set to True.

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• Does using functional languages help against computing values repeatedly?

  - by sharptooth

  Consider a function f(x,y): f(x,0) = x*x; f(0,y) = y*(y + 1); f(x,y) = f(x,y-1) + f(x-1,y); If one tries to implement that recursively in some language like C++ he will encounter a problem. Suppose the function is first called with x = x0 and y = y0. Then for any pair (x,y) where 0 <= x < x0 and 0 <= y < y0 the intermediate values will be computed multiple times - recursive calls will form a huge tree in which multiple leaves will in fact contain the same pairs (x,y). For pairs (x,y) where x and y are both close to 0 values will be computed numerous times. For instance, I tested a similar function implemented in C++ - for x=20 and y=20 its computation takes about 4 hours (yes, four Earth hours!). Obviously the implementation can be rewritten in such way that repeated computation doesn't occur - either iteratively or with a cache table. The question is: will functional languages perform any better and avoid repeated computations when implementing a function like above recursively?

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• A good way to write unit tests

  - by bobobobo

  So, I previously wasn't really in the practice of writing unit tests - now I kind of am and I need to check if I'm on the right track. Say you have a class that deals with math computations. class Vector3 { public: // Yes, public. float x,y,z ; // ... ctors ... } ; Vector3 operator+( const Vector3& a, const Vector3 &b ) { return Vector3( a.x + b.y /* oops!! hence the need for unit testing.. */, a.y + b.y, a.z + b.z ) ; } There are 2 ways I can really think of to do a unit test on a Vector class: 1) Hand-solve some problems, then hard code the numbers into the unit test and pass only if equal to your hand and hard-coded result bool UnitTest_ClassVector3_operatorPlus() { Vector3 a( 2, 3, 4 ) ; Vector3 b( 5, 6, 7 ) ; Vector3 result = a + b ; // "expected" is computed outside of computer, and // hard coded here. For more complicated operations like // arbitrary axis rotation this takes a bit of paperwork, // but only the final result will ever be entered here. Vector3 expected( 7, 9, 11 ) ; if( result.isNear( expected ) ) return PASS ; else return FAIL ; } 2) Rewrite the computation code very carefully inside the unit test. bool UnitTest_ClassVector3_operatorPlus() { Vector3 a( 2, 3, 4 ) ; Vector3 b( 5, 6, 7 ) ; Vector3 result = a + b ; // "expected" is computed HERE. This // means all you've done is coded the // same thing twice, hopefully not having // repeated the same mistake again Vector3 expected( 2 + 5, 6 + 3, 4 + 7 ) ; if( result.isNear( expected ) ) return PASS ; else return FAIL ; } Or is there another way to do something like this?

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• Watching a variable for changes without polling.

  - by milkfilk

  I'm using a framework called Processing which is basically a Java applet. It has the ability to do key events because Applet can. You can also roll your own callbacks of sorts into the parent. I'm not doing that right now and maybe that's the solution. For now, I'm looking for a more POJO solution. So I wrote some examples to illustrate my question. Please ignore using key events on the command line (console). Certainly this would be a very clean solution but it's not possible on the command line and my actual app isn't a command line app. In fact, a key event would be a good solution for me but I'm trying to understand events and polling beyond just keyboard specific problems. Both these examples flip a boolean. When the boolean flips, I want to fire something once. I could wrap the boolean in an Object so if the Object changes, I could fire an event too. I just don't want to poll with an if() statement unnecessarily. import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; /* * Example of checking a variable for changes. * Uses dumb if() and polls continuously. */ public class NotAvoidingPolling { public static void main(String[] args) { boolean typedA = false; String input = ""; System.out.println("Type 'a' please."); while (true) { InputStreamReader isr = new InputStreamReader(System.in); BufferedReader br = new BufferedReader(isr); try { input = br.readLine(); } catch (IOException ioException) { System.out.println("IO Error."); System.exit(1); } // contrived state change logic if (input.equals("a")) { typedA = true; } else { typedA = false; } // problem: this is polling. if (typedA) System.out.println("Typed 'a'."); } } } Running this outputs: Type 'a' please. a Typed 'a'. On some forums people suggested using an Observer. And although this decouples the event handler from class being observed, I still have an if() on a forever loop. import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.util.Observable; import java.util.Observer; /* * Example of checking a variable for changes. * This uses an observer to decouple the handler feedback * out of the main() but still is polling. */ public class ObserverStillPolling { boolean typedA = false; public static void main(String[] args) { // this ObserverStillPolling o = new ObserverStillPolling(); final MyEvent myEvent = new MyEvent(o); final MyHandler myHandler = new MyHandler(); myEvent.addObserver(myHandler); // subscribe // watch for event forever Thread thread = new Thread(myEvent); thread.start(); System.out.println("Type 'a' please."); String input = ""; while (true) { InputStreamReader isr = new InputStreamReader(System.in); BufferedReader br = new BufferedReader(isr); try { input = br.readLine(); } catch (IOException ioException) { System.out.println("IO Error."); System.exit(1); } // contrived state change logic // but it's decoupled now because there's no handler here. if (input.equals("a")) { o.typedA = true; } } } } class MyEvent extends Observable implements Runnable { // boolean typedA; ObserverStillPolling o; public MyEvent(ObserverStillPolling o) { this.o = o; } public void run() { // watch the main forever while (true) { // event fire if (this.o.typedA) { setChanged(); // in reality, you'd pass something more useful notifyObservers("You just typed 'a'."); // reset this.o.typedA = false; } } } } class MyHandler implements Observer { public void update(Observable obj, Object arg) { // handle event if (arg instanceof String) { System.out.println("We received:" + (String) arg); } } } Running this outputs: Type 'a' please. a We received:You just typed 'a'. I'd be ok if the if() was a NOOP on the CPU. But it's really comparing every pass. I see real CPU load. This is as bad as polling. I can maybe throttle it back with a sleep or compare the elapsed time since last update but this is not event driven. It's just less polling. So how can I do this smarter? How can I watch a POJO for changes without polling? In C# there seems to be something interesting called properties. I'm not a C# guy so maybe this isn't as magical as I think. private void SendPropertyChanging(string property) { if (this.PropertyChanging != null) { this.PropertyChanging(this, new PropertyChangingEventArgs(property)); } }

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• How can I create a fast, real-time, fixed length glowing ray?

  - by igf

  Similar to the disintegrate skill in Diablo 3. It should not light other objects in scene. Just glowing and animated. Like in this video http://www.youtube.com/watch?v=D_c4x6aQAG8. Should I use pack of pre-computed glow sources textures for each frame of ray animation like in this article http://http.developer.nvidia.com/GPUGems/gpugems_ch21.html and put it in bloom shader? Is there any other efficient ways to achive this effect? I'm using OpenGL ES 2.0.

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• Composite Moon Map Offers Stunning Views of the Lunar Surface [Astronomy]

  - by Jason Fitzpatrick

  Researchers at Arizona State University have stitched together a massive high-resolution map of the moon; seen the moon in astounding detail. Using images fro the Lunar Reconnaissance Orbiter (LRO) they carefully stitch a massive map of the moon with a higher resolution than the public has ever seen before: The WAC has a pixel scale of about 75 meters, and with an average altitude of 50 km, a WAC image swath is 70 km wide across the ground-track. Because the equatorial distance between orbits is about 30 km, there is nearly complete orbit-to-orbit stereo overlap all the way around the Moon, every month. Using digital photogrammetric techniques, a terrain model was computed from this stereo overlap. Hit up the link below to check out the images and the process they used. Lunar Topography as Never Seen Before [via NASA] How to Make the Kindle Fire Silk Browser *Actually* Fast! Amazon’s New Kindle Fire Tablet: the How-To Geek Review HTG Explains: How Hackers Take Over Web Sites with SQL Injection / DDoS

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• Explaining Explain Plan Notes for Auto DOP

  - by jean-pierre.dijcks

  I've recently gotten some questions around "why do I not see a parallel plan" while Auto DOP is on (I think)...? It is probably worthwhile to quickly go over some of the ways to find out what Auto DOP was thinking. In general, there is no need to go tracing sessions and look under the hood. The thing to start with is to do an explain plan on your statement and to look at the parameter settings on the system. Parameter Settings to Look At First and foremost, make sure that parallel_degree_policy = AUTO. If you have that parameter set to LIMITED you will not have queuing and we will only do the auto magic if your objects are set to default parallel (so no degree specified). Next you want to look at the value of parallel_degree_limit. It is typically set to CPU, which in default settings equates to the Default DOP of the system. If you are testing Auto DOP itself and the impact it has on performance you may want to leave it at this CPU setting. If you are running concurrent statements you may want to give this some more thoughts. See here for more information. In general, do stick with either CPU or with a specific number. For now avoid the IO setting as I've seen some mixed results with that... In 11.2.0.2 you should also check that IO Calibrate has been run. Best to simply do a: SQL> select * from V$IO_CALIBRATION_STATUS; STATUS        CALIBRATION_TIME ------------- ---------------------------------------------------------------- READY         04-JAN-11 10.04.13.104 AM You should see that your IO Calibrate is READY and therefore Auto DOP is ready. In any case, if you did not run the IO Calibrate step you will get the following note in the explain plan: Note -----    - automatic DOP: skipped because of IO calibrate statistics are missing One more note on calibrate_io, if you do not have asynchronous IO enabled you will see:  ERROR at line 1: ORA-56708: Could not find any datafiles with asynchronous i/o capability ORA-06512: at "SYS.DBMS_RMIN", line 463 ORA-06512: at "SYS.DBMS_RESOURCE_MANAGER", line 1296 ORA-06512: at line 7 While this is changed in some fixes to the calibrate procedure, you should really consider switching asynchronous IO on for your data warehouse. Explain Plan Explanation To see the notes that are shown and explained here (and the above little snippet ) you can use a simple explain plan mechanism. There should  be no need to add +parallel etc. explain plan for <statement> SELECT PLAN_TABLE_OUTPUT FROM TABLE(DBMS_XPLAN.DISPLAY()); Auto DOP The note structure displaying why Auto DOP did not work (with the exception noted above on IO Calibrate) is like this: Automatic degree of parallelism is disabled: <reason> These are the reason codes: Parameter -  parallel_degree_policy = manual which will not allow Auto DOP to kick in  Hint - One of the following hints are used NOPARALLEL, PARALLEL(1), PARALLEL(MANUAL) Outline - A SQL outline of an older version (before 11.2) is used SQL property restriction - The statement type does not allow for parallel processing Rule-based mode - Instead of the Cost Based Optimizer the system is using the RBO Recursive SQL statement - The statement type does not allow for parallel processing pq disabled/pdml disabled/pddl disabled - For some reason (alter session?) parallelism is disabled Limited mode but no parallel objects referenced - your parallel_degree_policy = LIMITED and no objects in the statement are decorated with the default PARALLEL degree. In most cases all objects have a specific degree in which case Auto DOP will honor that degree. Parallel Degree Limited When Auto DOP does it works you may see the cap you imposed with parallel_degree_limit showing up in the note section of the explain plan: Note -----    - automatic DOP: Computed Degree of Parallelism is 16 because of degree limit This is an obvious indication that your are being capped for this statement. There is one quite interesting one that happens when you are being capped at DOP = 1. First of you get a serial plan and the note changes slightly in that it does not indicate it is being capped (we hope to update the note at some point in time to be more specific). It right now looks like this: Note -----    - automatic DOP: Computed Degree of Parallelism is 1 Dynamic Sampling With 11.2.0.2 you will start seeing another interesting change in parallel plans, and since we are talking about the note section here, I figured we throw this in for good measure. If we deem the parallel (!) statement complex enough, we will enact dynamic sampling on your query. This happens as long as you did not change the default for dynamic sampling on the system. The note looks like this: Note ----- - dynamic sampling used for this statement (level=5)

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