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  • SAB BizTalk Archiving Pipeline Component - Codeplex

    - by Stuart Brierley
    In an effort to give a little more to the BizTalk development community, I have created my first Codeplex project. The SAB BizTalk Archiving Pipeline Component was written using Visual Studio 2010 with BizTalk Server 2010 intended as the target platform.  It is currently at version 0.1, meaning that I have not yet completed all the intended functionality and have so far carried out a limited number of tests.  It does however archive files within the bounds of the functionailty so far implemented and seems to be stable in use. It is based on a recent evolution of a basic archiving component that I wrote in the past, and it is my hope that it will continue to evolve in the coming months. This work was inspired by some old posts by Gilles Zunino and Jeff Lynch.   You can download the documentation, source code or component dll from Codeplex, but to give you a taste here is the first section of the documentation to whet your appetite: SAB BizTalk Archiving Pipeline Component   The SAB BizTalk Archiving Pipeline Component has been developed to allow custom piplelines to be created that can archive messages at any stage of pipeline processing.   It works in both receive and send pipelines and will archive messages to file based on the configuration applied to the component in the BizTalk Administration Console.   The Archiving Pipeline Component has been coded for use with BizTalk Server 2010. Use with other versions of BizTalk has not been tested.   The Archiving Pipeline component is supplied as a dll file that should be placed in the BizTalk Server Pipeline Components folder. It can then be used when developing custom pipelines to be deployed as a part of your BizTalk Server applications.   This version of the component allows you to use a number of generic messaging macros and also a small number that are specific to the FILE adapter. It is intended to extend these macros to cover context properties from other adapters in future releases.     Archive Pipeline Parameters As with all pipeline components, the following parameters can be set when creating your custom pipeline and at runtime via the administration console.   Enabled:              Enables and disables the archive process.                                 True; messages will be archived.   False; messages will be passed to the next stage in the pipeline without performing any processing.   File Name:          The file name of the archived message.   Allows the component to build the archive filename at run-time; based on the values entered, the permitted macros and data extracted from the message context properties.   e.g.        %FileReceivedFileName%-%InterchangeSequenceNumber%   File Mask:           The extension to be added to the File Name following all Macro processing.   e.g.        .xml   File Path:             The path on which the archived message should be saved.   Allows the component to build the archive directory at run-time; based on the values entered, permitted macros and data extracted from the message context properties.   e.g.        C:\Archive\%ReceivePortName%\%Year%\%Month%\%Day%\                   \\ArchiveShare\%ReceivePortName%\%Date%\     Overwrite:          Enables and disables existing file overwrites.   True; any existing file with the same File Path/Name combination (following macro replacement) will be overwritten.   False; any existing file with the same File Path/Name combination (following macro replacement) will not be overwritten.  The current message will be archived with a GUID appended to the File Name.

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  • Flexible design - customizable entity model, UI and workflow

    - by Ngm
    Hi All, I want to achieve the following aspects in the software I am building: 1. Customizable entity model 2. Customizable UI 3. Customizable workflow I have thought about an approach to achieve this, I want you to review this and make suggestions: Entity objects should be plain objects and will hold just data Separate Entity model and DB Schema by using an framework (like NHibernate?). This will allow easy modification of entity objects. Business logic to fetch/modify entities has to be granular enough so that they can be invoked as part of the workflow. Business objects should not hold any state, and hence will contain only static methods The workflow will decide depending upon the "state" of an entity/entities which methods on business object/objects to invoke. The workflow should obtain the results of the processing and then pass on the business objects to the appropriate UI screen. The UI screen has to contain instructions about how to display a given entity/entites. Possibly the UI has to be generated dynamically based on a set of UI instructions. (like XUL) What do you think about this approach? Suggest which existing frameworks (like NHiberante, Window Workflow) fit into this model, so that I will not spend time on coding these frameworks Also suggest is there any asp.net framework that can generate dynamic asp.net ajax pages based on a set of UI instructions (like Mozilla XUL)? I have recently been exploring Apache Ofbiz and was impressed by its ability to customize most areas of the application: UI, workflow, entities. Is there any similar (not necessarily an ERP system) application developed in C#/.Net which offers a similar level of customization? I am looking for examples of applications developed in C# that are highly customizable in terms of UI, Workflow and Entity Model

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  • What the best way to wire up Entity Framework database context (model) to ViewModel in MVVM WPF?

    - by hal9k2
    As in the question above: What the best way to wire up Entity Framework database model (context) to viewModel in MVVM (WPF)? I am learning MVVM pattern in WPF, alot of examples shows how to implement model to viewModel, but models in that examples are just simple classes, I want to use MVVM together with entity framework model (base first approach). Whats the best way to wire model to viewModel. Thanks for answers. //ctor of ViewModel public ViewModel() { db = new PackageShipmentDBEntities(); // Entity Framework generated class ListaZBazy = new ObservableCollection<Pack>(db.Packs.Where(w => w.IsSent == false)); } This is my usual ctor of ViewModel, think there is a better way, I was reading about repository pattern, not sure if I can adapt this to WPF MVVM

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  • 2-Way databinding with Entity Framework and WPF DataGrid

    - by Mike Gates
    I'm having trouble adding an Entity Framework entity to a ObjectContext's EntitySet automatically using the WPF 4.0 DataGrid's add functionality. Here's the setup: DataGrid--BoundTo--ListCollectionView--BoundTo--EntitySet When I interactively add a row to the DataGrid, the EntitySet does not have a new entity added to it. Updating the row's cell data does in fact update the bound entity's properties, however. Any idea what I could be doing wrong?

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  • Entity Framework 4 - Delay Loading Expensive Fields

    - by JohnnyO
    I know this same question was asked for Entity Framework 1, but now that Entity Framework 4 has come out, and Microsoft claims that it provides all of the features of Linq to Sql + more, does Entity Framework now support lazy loading expensive properties? In Linq to Sql, this is extremely easy. There's a Delay Loaded option on any property (accessible through the Designer) that can simply be toggled on or off. Is there something similar in Entity Framework? Thanks

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  • How to model my database when using entity framework 4?

    - by Junior Ewing
    Trying to wrap my head around the best approach in modelling a database when we are using Entity Framework 4 as the ORM layer. We are going to use asp.net mvc 2 for the application. Is it worth trying to model using the class diagram modeller that comes with Visual Studio 2010 where you graphically configure your models into the EDMX file and then generate out the database structure? I have run into a bunch of non trivial issues and for complex many to many mappings or multi primary key entities the answer is not that obvious even after poking around a while with the tools. I figure its easy at this point to give up and start modelling the DB using real, working DB modelling tools and then try to generate out the EDMX from the database, rather than trying to do the model first approach.

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  • Entity Framework 4 - Handling very large (1000+ tables) data models?

    - by David Kreps
    We've got a database with over 1000+ tables and would like to consider using EF4 for our data access layer, but I'm concerned about the practical realities of using it for such a large data model. I've seen this question and read about the suggested solutions here and here. These may work, but appear to refer to the first version of the Entity Framework (and are more complex than I'd like). Does anyone know if these solutions have been improved upon in EF4? Or have other suggestions all together? Thanks.

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  • Obstacle Avoidance steering behavior: how can an entity avoid an obstacle while other forces are acting on the entity?

    - by Prog
    I'm trying to implement the Obstacle Avoidance steering behavior in my 2D game. Currently my approach is to apply a force on the entity, in the direction of the normal of the heading, scaled by a number that gets bigger the closer we are to the obstacle. This is supposed to push the entity to the side and avoid the obstacle that blocks it's way. However, in the same time that my entity tries to avoid an obstacle, it Seeks to a point more or less behind the obstacle (which is the reason it needs to avoid the obstacle in the first place). The Seek algorithm constantly applies a force on the entity that pushes it (more or less) in the direction of the obstacle, while the Obstacle Avoidance algorithm constantly applies a force that pushes the entity away (more accurately, to the side) of the obstacle. The result is that sometimes the entity succesfully avoids the obstacle, and sometimes it collides with it, depending on the strength of the avoidance force I'm applying. How can I make sure that a force will succeed in steering the entity in some direction, while other forces are currently acting on the entity? (And while still looking natural). I can't allow entities to collide with obstacles when realistically they should be able to easily avoid them, doesn't matter what they're currently doing. Also, the Obstacle Avoidance algorithm is made exactly for the case where another force is acting on the entity. Otherwise it wouldn't be moving and there would be no need to avoid anything. So maybe I'm missing something. Thanks

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  • Entity/Component based engine rendering separation from logic

    - by Denis Narushevich
    I noticed in Unity3D that each gameObject(entity) have its own renderer component, as far I understand, such component handle rendering logic. I wonder if it is a common practice in entity/component based engines, when single entity have renderer components and logic components such as position, behavior altogether in one box? Such approach sound odd to me, in my understanding entity itself belongs to logic part and shouldn't contain any render specific things inside. With such approach it is impossible to swap renderers, it would require to rewrite all that customized renderers. The way I would do it is, that entity would contain only logic specific components, like AI,transform,scripts plus reference to mesh, or sprite. Then some entity with Camera component would store all references to object that is visible to the camera. And in order to render all that stuff I would have to pass Camera reference to Renderer class and render all sprites,meshes of visible entities. Is such approach somehow wrong?

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  • 2-Way databinding with Entity Framework and WPF DataGrid , is Possible ?

    - by Panindra
    i am working on POS application using SQL CE , WPF , Entity framework 3.5sp2 and iam trying to use data grid as my Order Entry Control for User to enter Products Order . Iam plannning to bind this to enitiy frmae work model , abd looking for 2 way updating ? private void button1_Click(object sender, RoutedEventArgs e) { using (MasterEntities nwEntities = new MasterEntities()) { var users = from d in nwEntities.Companies select new { d.CompanyId, d.CompanyName, d.Place }; listBox1.DataContext = users; dataGrid1.DataContext = users; // foreach (String c in customers) // { // MessageBox.Show(c.ToString()); // } } } When try to double clikc on the datagrid it through s a error with Caption " Invalid Operation Execption was unhandled " and Message " A TwoWay or OneWayToSource binding cannot work on the read-only property 'CompanyId' of type '<f__AnonymousType0`3[System.Int32,System.String,System.String]'. whats wrong here and my xaml coding goes like this <Grid> <ListBox Name="listBox1" ItemsSource="{Binding}" /> <Button Content="Show " Name="button1" Click="button1_Click" /> <DataGrid AutoGenerateColumns="False" Name="dataGrid1" ItemsSource="{Binding}" > <DataGrid.Columns> <DataGridTextColumn Header=" ID" Binding="{Binding CompanyId}"/> <DataGridTextColumn Header="Company Name" Binding="{Binding CompanyName}"/> <DataGridTextColumn Header="Place" Binding="{Binding Place}" /> </DataGrid.Columns> </DataGrid> </Grid> EDITED : i made the changes shown by @vorrtex, But, then i added another button to save the chages and in button click event i added follwing code , butit showing Updating error private void button2_Click(object sender, RoutedEventArgs e) { nwEntities.SaveChanges(); }

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  • A question about entities, roles and interfaces in Entity Framework 4.

    - by mvole
    Hi, I am an experienced .NET developer but new to EF - so please bear with me. I will use an example of a college application to illustrate my problem. I have these user roles: Lecturer, Student, Administrator. In my code I envisage working with these entities as distinct classes so e.g. a Lecturer teaches a collection of Students. And work with 'is Student' 'TypeOf' etc. Each of these entities share lots of common properties/methods e.g. they can all log onto the system and do stuff related to their role. In EF designer I can create a base entity Person (or User...) and have Lecturer, Student and Administrator all inherit from that. The difficulty I have is that a Lecturer can be an Administrator - and in fact on occasion a Student can be a Lecturer. If I were to add other entities such as Employee and Warden then this gets even more of an issue. I could presumably work with Interfaces so a person could implement ILecturer and IStudent, however I do not see how this fits within EF. I would like to work within the EF designer if possible and I'm working model-first (coding in C#). So any help and advice/samples would be very welcome and much appreciated. Thanks

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  • Entity Framework LINQ Query using Custom C# Class Method - Once yes, once no - because executing on the client or in SQL?

    - by BrooklynDev
    I have two Entity Framework 4 Linq queries I wrote that make use of a custom class method, one works and one does not: The custom method is: public static DateTime GetLastReadToDate(string fbaUsername, Discussion discussion) { return (discussion.DiscussionUserReads.Where(dur => dur.User.aspnet_User.UserName == fbaUsername).FirstOrDefault() ?? new DiscussionUserRead { ReadToDate = DateTime.Now.AddYears(-99) }).ReadToDate; } The linq query that works calls a from after a from, the equivalent of SelectMany(): from g in oc.Users.Where(u => u.aspnet_User.UserName == fbaUsername).First().Groups from d in g.Discussions select new { UnReadPostCount = d.Posts.Where(p => p.CreatedDate > DiscussionRepository.GetLastReadToDate(fbaUsername, p.Discussion)).Count() }; The query that does not work is more like a regular select: from d in oc.Discussions where d.Group.Name == "Student" select new { UnReadPostCount = d.Posts.Where(p => p.CreatedDate > DiscussionRepository.GetLastReadToDate(fbaUsername, p.Discussion)).Count(), }; The error I get is: LINQ to Entities does not recognize the method 'System.DateTime GetLastReadToDate(System.String, Discussion)' method, and this method cannot be translated into a store expression. My question is, why am I able to use my custom GetLastReadToDate() method in the first query and not the second? I suppose this has something to do with what gets executed on the db server and what gets executed on the client? These queries seem to use the GetLastReadToDate() method so similarly though, I'm wondering why would work for the first and not the second, and most importantly if there's a way to factor common query syntax like what's in the GetLastReadToDate() method into a separate location to be reused in several different places LINQ queries. Please note all these queries are sharing the same object context.

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  • Terminology: Difference between software interface, software component, software unit, software modu

    - by JamieH
    I see these terms used quite a lot between various authors, but I can't seem to fix upon definitive definitions. From my POV a software interface is a "type" specifying the way in which a software component may be used by other softare components. But what exactly a software component is I'm not entirely sure (and it seems no-one else is either). Same goes for software unit, and software module, although I suspect that a software unit is a smaller, ahem, unit than a component, and a software module has something to do with packaging. I hope this is not deemed (and downvoted) as frivulous, as I have serious intent in the asking.

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  • Entity Relationship Diagram - Relationship Strength?

    - by 01010011
    Hi, I am trying to figure out under what circumstances I should use weak (non-identifying) relationships (where the primary key of the related entity does not contain a primary key component of the parent entity), verses when I should use strong (identifying) relationships (primary key of the related entity contains a primary key component of the parent entity). For example, when designing an Entity Relationship Diagram , if I have two entities, (e.g. book and purchaser), how do I know when to choose the solid Crows Foot or the dashed Crows Foot to connect the two entities? Any assistance will be appreciated. Thanks in advance.

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  • Entity Framework mant to many insert

    - by Jacob
    I've been playing around with Entity Framework v2 and added some code to insert new entity with many to many relationship , lets say this entity is called meeting. I add hours to meeting : meeting.Hours.Add(hour); and I get different errors on different occasions On Update : Cannot insert the value NULL into column 'Meetings_Id', table 'Plan.dbo.MeetingHour'; column does not allow nulls. INSERT fails. The statement has been terminated. On Inset : An item with the same key has already been added. But the tricky party is that if I add this manually trough SQL Server Management Studio , I can update the entity with the same value , clearing it first (meeting.Hour.Clear()) Can't see what could be the problem , maybe entity model isn't mapped correctly ?

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  • Difference between "traditional" COM and COM+ (in Component Services)

    - by kizzx2
    By the "traditional" way I mean registering the DLL in registry. There seems to be another method to set up it by going to mmc-Component Services-COM+ Applications and adding the .tlb file. I have a COM library that supports both methods. When it installs, it registers itself in the registry as a COM component and it works fine. However, when I added the .tlb file using the Component Services method, the behavior seems to be different and it starts giving out errors. I suspect it has something to do with marshaling and inter-process object transfer? (Sorry, I'm really a noob in the COM area) Can anyone point me to a good resource to clear my understanding?

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  • flex/actionscript client entity state refresh on JPA update using Pimento EntityManager

    - by Chris
    My Flex application uses a client-side pimento EntityManager which fetches quite a few objects and associations. It does this by forcing eager fetching of particular association ends in the form of fetch plans. I would like to update the client whenever a change has been made to an entity existing in the EntityManager's cache. Is it possible to update the state of the changed entity ONLY, including updating which entities are associated, without resetting the state of these associated entities? I have setup an EntityListener with a JPA post-update method that notifies clients when a persisted entity has been updated. I want this to trigger a refresh for the modified client-side entity, but calling EntityManager.refresh(entity) resets all lazy associations to proxies. Initializing these proxies resets the associated entities, even if they were loaded previously. I'm looking for an efficient way to keep the client's state in synch with the server's state, at least with respect to the entities that have already been retrieved by the initial load.

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  • Deploying backing bean with composite component in separate jar

    - by Checkoff
    I have some difficulties deploying my web app on JBoss AS 6.1. My current Project is separated into the main web app (controller/managed beans & web frontend using JSF 2 facelets) and one jar with the composite components + backing beans. But when I try to access the page I got an error that the specified component type could not be instantiated. Copying the backing bean into the main web app solves the problem, but this isn't what I want. So is there anything to pay attention to? The backing bean looks like @FacesComponent(value = "elementBase") public class ElementBase extends UINamingContainer { ... } and the composite components interface <composite:interface componentType="elementBase"> ... some attributes </composite:interface> The structure of the jar is the following -- META-INF |-- resources | |-- components | |-- elementBase.xhtml -- com |-- example | |-- ElementBase.class I've also tried to add faces-config.xml within META-INF folder, with the component type, but the component type was still not found.

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  • Custom component creation - how to add small icon representing component in Tool Palette?

    - by Wodzu
    Please bear in mind that I've read all the instructions I could find about adding component icon to my custom component. And I am able to do this when we talk about the icon size which is 24x24 pixels. I see the icon when a component is dropped on the form. However I can not see the small 16x16 icon which should be displayed when browsing Tool Palette. I've read that I should name my two other BMP files which are contained in DCR file like this: MyComponentName16 [for 16x16 BMP file] MyComponentName32 [for 32x32 BMP file] Unfortunately this does not seem to work, I've tried to restart Delphi few times in hope that it might be the case of not refreshing something, but without any success. Any ideas?

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  • EF 4.1 Code First Detaching Entity

    - by Nazaf
    I am trying to add an entity to the DB. Once I have added it, I want to detach it, so I can manipulate the object safely without making any changes to the DB. After calling context.SaveChanges() I do the following to detach the entity: // save context.Stories.Add(story); // attach tags. They already exists in the database foreach(var tag in story.Tags) context.Entry(tag).State = System.Data.EntityState.Unchanged; context.SaveChanges(); context.Entry(story).State = System.Data.EntityState.Detached; However, changing the entity state to DETACHED will remove all related entities associated with the my entity. Is there a way to stop this ? If I don't detach the entity, all my changes are sent to the DB next time I call context.SaveChanges() Thanks!!

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  • Slides and links for Entity Framework 4 and Azure from Devweek 2010

    - by Eric Nelson
    Last week (March 2010) I presented on Entity Framework 4 and the Windows Azure Platform at www.devweek.com. As usual, it was a great conference and I caught up with lots of old friends and made some new ones along the way. Entity Framework 4 Entity Framework 4 In Microsoft Visual Studio 2010 View more presentations from Eric Nelson. Windows Azure and SQL Azure Building An Application For Windows Azure And Sql Azure View more presentations from Eric Nelson. Entity Framework 4 Related Links Poll on Entity Framework 4 – one year on 101 EF4 Resources Recent resources on Entity Framework 4 Installing all the bits to demo Entity Framework 4 on the Visual Studio 2010 Release Candidate Azure Related Links UK Azure Online Community – join today. UK Windows Azure Site Start working with Windows Azure TCO and ROI calculator for Windows Azure

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  • Row Count Plus Transformation

    As the name suggests we have taken the current Row Count Transform that is provided by Microsoft in the Integration Services toolbox and we have recreated the functionality and extended upon it. There are two things about the current version that we thought could do with cleaning up Lack of a custom UI You have to type the variable name yourself In the Row Count Plus Transformation we solve these issues for you. Another thing we thought was missing is the ability to calculate the time taken between components in the pipeline. An example usage would be that you want to know how many rows flowed between Component A and Component B and how long it took. Again we have solved this issue. Credit must go to Erik Veerman of Solid Quality Learning for the idea behind noting the duration. We were looking at one of his packages and saw that he was doing something very similar but he was using a Script Component as a transformation. Our philosophy is that if you have to write or Copy and Paste the same piece of code more than once then you should be thinking about a custom component and here it is. The Row Count Plus Transformation populates variables with the values returned from; Counting the rows that have flowed through the path Returning the time in seconds between when it first saw a row come down this path and when it saw the final row. It is possible to leave both these boxes blank and the component will still work.   All input columns are passed through the transformation unaltered, you are not permitted to change or add to the inputs or outputs of this component. Optionally you can set the component to fire an event, which happens during the PostExecute phase of the execution. This can be useful to improve visibility of this information, such that it is captured in package logging, or can be used to drive workflow in the case of an error event. Properties Property Data Type Description OutputRowCountVariable String The name of the variable into which the amount of row read will be passed (Optional). OutputDurationVariable String The name of the variable into which the duration in seconds will be passed. (Optional). EventType RowCountPlusTransform.EventType The type of event to fire during post execute, included in which are the row count and duration values. RowCountPlusTransform.EventType Enumeration Name Value Description None 0 Do not fire any event. Information 1 Fire an Information event. Warning 2 Fire a Warning event. Error 3 Fire an Error event. Installation The component is provided as an MSI file which you can download and run to install it. This simply places the files on disk in the correct locations and also installs the assemblies in the Global Assembly Cache as per Microsoft’s recommendations. You may need to restart the SQL Server Integration Services service, as this caches information about what components are installed, as well as restarting any open instances of Business Intelligence Development Studio (BIDS) / Visual Studio that you may be using to build your SSIS packages. For 2005/2008 Only - Finally you will have to add the transformation to the Visual Studio toolbox manually. Right-click the toolbox, and select Choose Items.... Select the SSIS Data Flow Items tab, and then check the Row Count Plus Transformation in the Choose Toolbox Items window. This process has been described in detail in the related FAQ entry for How do I install a task or transform component? We recommend you follow best practice and apply the current Microsoft SQL Server Service pack to your SQL Server servers and workstations, and this component requires a minimum of SQL Server 2005 Service Pack 1. Downloads The Row Number Transformation is available for SQL Server 2005, SQL Server 2008 (includes R2) and SQL Server 2012. Please choose the version to match your SQL Server version, or you can install multiple versions and use them side by side if you have more than one version of SQL Server installed. Row Count Plus Transformation for SQL Server 2005 Row Count Plus Transformation for SQL Server 2008 Row Count Plus Transformation for SQL Server 2012 Version History SQL Server 2012 Version 3.0.0.6 - SQL Server 2012 release. Includes upgrade support for both 2005 and 2008 packages to 2012. (5 Jun 2012) SQL Server 2008 Version 2.0.0.5 - SQL Server 2008 release. (15 Oct 2008) SQL Server 2005 Version 1.1.0.43 - Bug fix for duration. For long running processes the duration second count may have been incorrect. (8 Sep 2006) Version 1.1.0.42 - SP1 Compatibility Testing. Added the ability to raise an event with the count and duration data for easier logging or workflow. (18 Jun 2006) Version 1.0.0.1 - SQL Server 2005 RTM. Made available as general public release. (20 Mar 2006) Screenshot Troubleshooting Make sure you have downloaded the version that matches your version of SQL Server. We offer separate downloads for SQL Server 2005, SQL Server 2008 and SQL Server 2012. If you get an error when you try and use the component along the lines of The component could not be added to the Data Flow task. Please verify that this component is properly installed.  ... The data flow object "Konesans ..." is not installed correctly on this computer, this usually indicates that the internal cache of SSIS components needs to be updated. This is held by the SSIS service, so you need restart the the SQL Server Integration Services service. You can do this from the Services applet in Control Panel or Administrative Tools in Windows. You can also restart the computer if you prefer. You may also need to restart any current instances of Business Intelligence Development Studio (BIDS) / Visual Studio that you may be using to build your SSIS packages. Once installation is complete you need to manually add the task to the toolbox before you will see it and to be able add it to packages - How do I install a task or transform component?

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  • Complex Entity Framework linked-graphs issue: how to limit change set / break the graph?

    - by Hightechrider
    I have an EDMX containing Sentences, and Words, say and a Sentence contains three Words, say. Appropriate FK relationships exist between the tables. I create some words: Word word1 = new Word(); Word word2 = ... I build a Sentence: Sentence x = new Sentence (word1, word2, word3); I build another Sentence: Sentence y = new Sentence (word1, word4, word5); I try to save x to the database, but EF builds a change set that includes everything, including y, word4 and word5 that aren't ready to save to the database. When SaveChanges() happens it throws an exception: Unable to determine the principal end of the ... relationship. Multiple added entities may have the same primary key. I think it does this because Word has an EntityCollection<Sentence> on it from the FK relationship between the two tables, and thus Sentence y is inextricably linked to Sentence x through word1. So I remove the Navigation Property Sentences from Word and try again. It still tries to put the entire graph into the change set. What suggestions do the Entity Framework experts have for ways to break this connection. Essentially what I want is a one-way mapping from Sentence to Word; I don't want an EntityCollection<Sentence> on Word and I don't want the object graph to get intertwined like this. Code sample: This puts two sentences into the database because Verb1 links them and EF explores the entire graph of existing objects and added objects when you do Add/SaveChanges. Word subject1 = new Word(){ Text = "Subject1"}; Word subject2 = new Word(){ Text = "Subject2"}; Word verb1 = new Word(){ Text = "Verb11"}; Word object1 = new Word(){ Text = "Object1"}; Word object2 = new Word(){ Text = "Object2"}; Sentence s1 = new Sentence(){Subject = subject1, Verb=verb1, Object=object1}; Sentence s2 = new Sentence(){Subject=subject2, Verb=verb1, Object=object2}; context.AddToSentences(s1); context.SaveChanges(); foreach (var s in context.Sentences) { Console.WriteLine(s.Subject + " " + s.Verb + " " + s.Object); }

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  • How far should an entity take care of its properties values by itself?

    - by Kharlos Dominguez
    Let's consider the following example of a class, which is an entity that I'm using through Entity Framework. - InvoiceHeader - BilledAmount (property, decimal) - PaidAmount (property, decimal) - Balance (property, decimal) I'm trying to find the best approach to keep Balance updated, based on the values of the two other properties (BilledAmount and PaidAmount). I'm torn between two practices here: Updating the balance amount every time BilledAmount and PaidAmount are updated (through their setters) Having a UpdateBalance() method that the callers would run on the object when appropriate. I am aware that I can just calculate the Balance in its getter. However, it isn't really possible because this is an entity field that needs to be saved back to the database, where it has an actual column, and where the calculated amount should be persisted to. My other worry about the automatically updating approach is that the calculated values might be a little bit different from what was originally saved to the database, due to rounding values (an older version of the software, was using floats, but now decimals). So, loading, let's say 2000 entities from the database could change their status and make the ORM believe that they have changed and be persisted back to the database the next time the SaveChanges() method is called on the context. It would trigger a mass of updates that I am not really interested in, or could cause problems, if the calculation methods changed (the entities fetched would lose their old values to be replaced by freshly recalculated ones, simply by being loaded). Then, let's take the example even further. Each invoice has some related invoice details, which also have BilledAmount, PaidAmount and Balance (I'm simplifying my actual business case for the sake of the example, so let's assume the customer can pay each item of the invoice separately rather than as a whole). If we consider the entity should take care of itself, any change of the child details should cause the Invoice totals to change as well. In a fully automated approach, a simple implementation would be looping through each detail of the invoice to recalculate the header totals, every time one the property changes. It probably would be fine for just a record, but if a lot of entities were fetched at once, it could create a significant overhead, as it would perform this process every time a new invoice detail record is fetched. Possibly worse, if the details are not already loaded, it could cause the ORM to lazy-load them, just to recalculate the balances. So far, I went with the Update() method-way, mainly for the reasons I explained above, but I wonder if it was right. I'm noticing I have to keep calling these methods quite often and at different places in my code and it is potential source of bugs. It also has a detrimental effect on data-binding because when the properties of the detail or header changes, the other properties are left out of date and the method has no way to be called. What is the recommended approach in this case?

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