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• Datagrid using usercontrol

  - by klawusel

  Hello I am fighting with this problem: I have a usercontrol which contains a textbox and a button (the button calls some functions to set the textbox's text), here is the xaml: <UserControl x:Class="UcSelect" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" x:Name="Control1Name" <Grid x:Name="grid1" MaxHeight="25"> <Grid.ColumnDefinitions> <ColumnDefinition /> <ColumnDefinition Width="25"/> </Grid.ColumnDefinitions> <Grid.RowDefinitions> <RowDefinition Height="25"/> </Grid.RowDefinitions> <TextBox x:Name="txSelect" Text="{Binding UcText, Mode=TwoWay}" /> <Button x:Name="pbSelect" Background="Red" Grid.Column="1" Click="pbSelect_Click">...</Button> </Grid> And here the code behind: Partial Public Class UcSelect Private Shared Sub textChangedCallBack(ByVal [property] As DependencyObject, ByVal args As DependencyPropertyChangedEventArgs) Dim UcSelectBox As UcSelect = DirectCast([property], UcSelect) End Sub Public Property UcText() As String Get Return GetValue(UcTextProperty) End Get Set(ByVal value As String) SetValue(UcTextProperty, value) End Set End Property Public Shared ReadOnly UcTextProperty As DependencyProperty = _ DependencyProperty.Register("UcText", _ GetType(String), GetType(UcSelect), _ New FrameworkPropertyMetadata(String.Empty, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, New PropertyChangedCallback(AddressOf textChangedCallBack))) Public Sub New() InitializeComponent() grid1.DataContext = Me End Sub Private Sub pbSelect_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) 'just demo UcText = UcText + "!" End Sub End Class The UserControl works fine when used as a single control in this way: <local:UcSelect Grid.Row="1" x:Name="ucSingle1" UcText="{Binding FirstName, Mode=TwoWay}"/> Now I wanted to use the control in a custom datagrid column. As I like to have binding support I choosed to derive from DataGridtextColumn instead of using a DataGridTemplateColumn, here is the derived column class: Public Class DerivedColumn Inherits DataGridTextColumn Protected Overloads Overrides Function GenerateElement(ByVal oCell As DataGridCell, ByVal oDataItem As Object) As FrameworkElement Dim oElement = MyBase.GenerateElement(oCell, oDataItem) Return oElement End Function Protected Overloads Overrides Function GenerateEditingElement(ByVal oCell As DataGridCell, ByVal oDataItem As Object) As FrameworkElement Dim oUc As New UcSelect Dim oBinding As Binding = CType(Me.Binding, Binding) oUc.SetBinding(UcSelect.UcTextProperty, oBinding) Return oUc End Function End Class The column is used in xaml in the following way: <local:DerivedColumn Header="Usercontrol" Binding="{Binding FirstName, Mode=TwoWay}"></local:DerivedColumn> If I start my program all seems to be fine, but changes I make in the custom column are not reflected in the object (property "FirstName"), the changes are simply rolled back when leaving the cell. I think there must be something wrong with my GenerateEditingElement code, but have no idea ... Any Help would really be appreciated Regards Klaus

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• Speaker at the German Visual FoxPro Developer Conference 2004

  The following is an excerpt from the UniversalThread conference coverage of the German Visual FoxPro Developer Conference 2004 written by Hans-Otto Lochmann, Armin Neudert and myself. TRACK Active FoxPro Pages Back in 1996 Peter Herzog invented a FoxPro based solution to provide intranet capabilities for one of his customers. Nearly at the same time Rick Strahl had the same task and created WestWind Web Connection (WWWC). The aspect that developers have to have a full Visual FoxPro development environment to create WWWC solutions was the starting point of a "personal sportive competition" of Peter to write his own solution. But the main aspect has to be that it doesn't rely on a full VFP version in order to run. The VFP runtime should enough and the source code has to be compiled and interpreted on the fly. So, as Microsoft released Active Server Pages a name for Peter's solution was found: Active FoxPro Pages (AFP). During the years many drawbacks, design aspects as well as technological hassles forced ProLib Software to refactor the product. This way many limits like DCOM configuration, file-based information transfer between Web server and AFP, missing features (like upload forms or other Web servers than IIS) and extensibility were eliminated. As a consequence ProLib Software decided to rewrite Active FoxPro Pages in mid of 2002 completely. Christof Wollenhaupt, before his marriage known as Christof Lange, and Jochen Kirstätter had to solve this task. AFP 3.0 was officially released at German Devcon in November 2002. Today AFP has six distributors world-wide and there is a lot more information available online than before version 3.0. Directly after a short welcome speech by Rainer Becker, Jochen Kirstätter - aka JoKi - opened today's AFP track and introduced the basic concepts how Active FoxPro Pages works in general, explained the AFP terminilogy and every single component, and presented a small Walk-Through about how to write an AFP-based Web solution. Actually his presentation slides themselves were an AFP Web application. This way it was easy to integrate accompanying AFP samples on the fly. Additionally it was shown that no Visual FoxPro development environment is needed to create a Web application. A simple text editor like NotePad or any WYSIWYG editor on the market is usable to fullfil customer's requirements.Welcome at least two new speakers - Nina Schwanzer and Bernhard Reiter. Both are working at ProLib Software and this year's conference is their first time as speakers. And they did their job very well. The whole session was kind of a "ping pong" game and those two complemented each other to keep the audience in tension. First, they described typical requirements a modern desktop application should fullfil - online registration and activation, auto-update capabilities, or even frontend to administer a Web application on a remote system via internet, and explained how possible solutions like Web Services (using the SOAP interface), DCOM, and even .NET might solve those requirements. But any of those ways has different drawbacks like complicated installation or configuration, or extraordinary download sizes. Next, they introduced a technology they developed and used in a customer's project: Active FoxPro Pages Remote Procedure Call (AFP RPC). [...]   In the next session JoKi described how to extend Active FoxPro Pages. On the one hand AFP provides a plugin interface, and on the other hand any addon for Visual FoxPro might be usable as well. During the first half he spoke about the plugin interface and wrote live a new AFP extension - the Devcon plugin. Later he questioned any former step and showed that a single AFP document may solve the problem as well. So, developing extensions is only interesting if they are re-usable and generic. At the end he talked about multiple interfaces for the same business logic. For instance plain VFP class, COM server and .NET integration. Currently there are several specialized AFP extensions for sending mail, for using cryptographic routines (ie. based on .NET classes), or enhanced methods to handle HTML/XML strings.Rainer Becker and Peter Herzog introduced a new development for Visual Extend (VFX) - an AFP form builder. With this builder creating an AFP Web form designed with Visual FoxPro's form designer was a matter of seconds. The builder itself is currently in pre-release status and will be part of the VFX framework in the future. It was very impressive to see that the whole design of a form as well as most parts of its functionality were exported to a combination of HTML, JavaScript and Active FoxPro Pages. At half-time Jürgen "wOOdy" Wondzinski and JoKi changed places with Rainer and Peter, and presented some Web solutions in AFP. [...] Visual FoxPro 9.0 und Linux Is Linux still a topic for Visual FoxPro developers based on the activities during this year? In his session Jochen Kirstätter - aka JoKi - went not through the technical steps and requirements on how to setup and run FoxPro on a Linux client. Instead, he explained what Linux actually is, and talked about the high variety of distributions. In fact there are a lot of distributions around but since some several years there are some specialized ones available: Live Distributions (aka LiveCDs).The intension of LiveCDs is to run a full-featured Linux operating system on any personal computer directly from a bootable medium, like CD, DVD, or even USB memory stick, without installation on a hard disk. One of the first Linux LiveCDs was made by Klaus Knopper and is well-known as Knoppix. Today, many other LiveCDs are based on the concepts of Knoppix. During the session Jochen booted Morphix, a very light-weighted LiveCD, on his notebook, and actually showed the attendees that testing and playing around with Linux is absolutely easy. Running a text processing application swept away most of the contrary aspects the audience had. Okay, where is the part about FoxPro? Well, there are several scenarios a customer might require usage of Linux, and actually with all of them FoxPro could deal with. I guess that one of the more common ones is the situation that a customer has a heterogeneous intranet with Windows clients and Linux servers, i.e. Windows XP Professional and any Linux distribution on their servers. Even in this scenario there are two variants hidden! Why? Well, on the one hand there is a software package called Samba, that provides Windows server capabilities to a Linux system, and on the other hand there are several SQL servers for Linux, like PostgreSQL, DB2 and MySQL. Either way, FoxPro is able to deal with these scenarios, but you as developer have to know what you are talking about with your customers. And even if there's no Windows operating system, you are able to provide a FoxPro-based solution. Using the wine library - wine stands for Wine Is Not an Emulator - you are able to run your VFP applications on Linux clients, too; but not without reading VFP's EULA. Licenses were also part the session, and Jochen discussed the meaning of Open Source and its misunderstanding throughout most developers. Open Source does not mean that it's without a fee. Instead, it stands for access to the source code of an application or tool. And, VFP itself is one of the best samples to explain Open Source due to fact that since years, VFP is shipped with the xSource.zip archive. [...]

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• Columnstore Case Study #2: Columnstore faster than SSAS Cube at DevCon Security

  - by aspiringgeek

  Preamble This is the second in a series of posts documenting big wins encountered using columnstore indexes in SQL Server 2012 & 2014.  Many of these can be found in my big deck along with details such as internals, best practices, caveats, etc.  The purpose of sharing the case studies in this context is to provide an easy-to-consume quick-reference alternative. See also Columnstore Case Study #1: MSIT SONAR Aggregations Why Columnstore? As stated previously, If we’re looking for a subset of columns from one or a few rows, given the right indexes, SQL Server can do a superlative job of providing an answer. If we’re asking a question which by design needs to hit lots of rows—DW, reporting, aggregations, grouping, scans, etc., SQL Server has never had a good mechanism—until columnstore. Columnstore indexes were introduced in SQL Server 2012. However, they're still largely unknown. Some adoption blockers existed; yet columnstore was nonetheless a game changer for many apps.  In SQL Server 2014, potential blockers have been largely removed & they're going to profoundly change the way we interact with our data.  The purpose of this series is to share the performance benefits of columnstore & documenting columnstore is a compelling reason to upgrade to SQL Server 2014. The Customer DevCon Security provides home & business security services & has been in business for 135 years. I met DevCon personnel while speaking to the Utah County SQL User Group on 20 February 2012. (Thanks to TJ Belt (b|@tjaybelt) & Ben Miller (b|@DBADuck) for the invitation which serendipitously coincided with the height of ski season.) The App: DevCon Security Reporting: Optimized & Ad Hoc Queries DevCon users interrogate a SQL Server 2012 Analysis Services cube via SSRS. In addition, the SQL Server 2012 relational back end is the target of ad hoc queries; this DW back end is refreshed nightly during a brief maintenance window via conventional table partition switching. SSRS, SSAS, & MDX Conventional relational structures were unable to provide adequate performance for user interaction for the SSRS reports. An SSAS solution was implemented requiring personnel to ramp up technically, including learning enough MDX to satisfy requirements. Ad Hoc Queries Even though the fact table is relatively small—only 22 million rows & 33GB—the table was a typical DW table in terms of its width: 137 columns, any of which could be the target of ad hoc interrogation. As is common in DW reporting scenarios such as this, it is often nearly to optimize for such queries using conventional indexing. DevCon DBAs & developers attended PASS 2012 & were introduced to the marvels of columnstore in a session presented by Klaus Aschenbrenner (b|@Aschenbrenner) The Details Classic vs. columnstore before-&-after metrics are impressive. Scenario   Conventional Structures   Columnstore   Δ SSRS via SSAS 10 - 12 seconds 1 second >10x Ad Hoc 5-7 minutes (300 - 420 seconds) 1 - 2 seconds >100x Here are two charts characterizing this data graphically.  The first is a linear representation of Report Duration (in seconds) for Conventional Structures vs. Columnstore Indexes.  As is so often the case when we chart such significant deltas, the linear scale doesn’t expose some the dramatically improved values corresponding to the columnstore metrics.  Just to make it fair here’s the same data represented logarithmically; yet even here the values corresponding to 1 –2 seconds aren’t visible.  The Wins Performance: Even prior to columnstore implementation, at 10 - 12 seconds canned report performance against the SSAS cube was tolerable. Yet the 1 second performance afterward is clearly better. As significant as that is, imagine the user experience re: ad hoc interrogation. The difference between several minutes vs. one or two seconds is a game changer, literally changing the way users interact with their data—no mental context switching, no wondering when the results will appear, no preoccupation with the spinning mind-numbing hurry-up-&-wait indicators.  As we’ve commonly found elsewhere, columnstore indexes here provided performance improvements of one, two, or more orders of magnitude. Simplified Infrastructure: Because in this case a nonclustered columnstore index on a conventional DW table was faster than an Analysis Services cube, the entire SSAS infrastructure was rendered superfluous & was retired. PASS Rocks: Once again, the value of attending PASS is proven out. The trip to Charlotte combined with eager & enquiring minds let directly to this success story. Find out more about the next PASS Summit here, hosted this year in Seattle on November 4 - 7, 2014. DevCon BI Team Lead Nathan Allan provided this unsolicited feedback: “What we found was pretty awesome. It has been a game changer for us in terms of the flexibility we can offer people that would like to get to the data in different ways.” Summary For DW, reports, & other BI workloads, columnstore often provides significant performance enhancements relative to conventional indexing.  I have documented here, the second in a series of reports on columnstore implementations, results from DevCon Security, a live customer production app for which performance increased by factors of from 10x to 100x for all report queries, including canned queries as well as reducing time for results for ad hoc queries from 5 - 7 minutes to 1 - 2 seconds. As a result of columnstore performance, the customer retired their SSAS infrastructure. I invite you to consider leveraging columnstore in your own environment. Let me know if you have any questions.

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• NHibernate which cache to use for WinForms application

  - by chiccodoro

  I have a C# WinForms application with a database backend (oracle) and use NHibernate for O/R mapping. I would like to reduce communication to the database as much as possible since the network in here is quite slow, so I read about second level caching. I found this quite good introduction, which lists the following available cache implementations. I'm wondering which implementation I should use for my application. The caching should be simple, it should not significantly slow down the first occurrence of a query, and it should not take much memory to load the implementing assemblies. (With NHibernate and Castle, the application already takes up to 80 MB of RAM!) Velocity: uses Microsoft Velocity which is a highly scalable in-memory application cache for all kinds of data. Prevalence: uses Bamboo.Prevalence as the cache provider. Bamboo.Prevalence is a .NET implementation of the object prevalence concept brought to life by Klaus Wuestefeld in Prevayler. Bamboo.Prevalence provides transparent object persistence to deterministic systems targeting the CLR. It offers persistent caching for smart client applications. SysCache: Uses System.Web.Caching.Cache as the cache provider. This means that you can rely on ASP.NET caching feature to understand how it works. SysCache2: Similar to NHibernate.Caches.SysCache, uses ASP.NET cache. This provider also supports SQL dependency-based expiration, meaning that it is possible to configure certain cache regions to automatically expire when the relevant data in the database changes. MemCache: uses memcached; memcached is a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load. Basically a distributed hash table. SharedCache: high-performance, distributed and replicated memory object caching system. See here and here for more info My considerations so far were: Velocity seems quite heavyweight and overkill (the files totally take 467 KB of disk space, haven't measured the RAM it takes so far because I didn't manage to make it run, see below) Prevalence, at least in my first attempt, slowed down my query from ~0.5 secs to ~5 secs, and caching didn't work (see below) SysCache seems to be for ASP.NET, not for winforms. MemCache and SharedCache seem to be for distributed scenarios. Which one would you suggest me to use? There would also be a built-in implementation, which of course is very lightweight, but the referenced article tells me that I "(...) should never use this cache provider for production code but only for testing." Besides the question which fits best into my situation I also faced problems with applying them: Velocity complained that "dcacheClient" tag not specified in the application configuration file. Specify valid tag in configuration file," although I created an app.config file for the assembly and pasted the example from this article. Prevalence, as mentioned above, heavily slowed down my first query, and the next time the exact same query was executed, another select was sent to the database. Maybe I should "externalize" this topic into another post. I will do that if someone tells me it is absolutely unusual that a query is slowed down so much and he needs further details to help me.

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