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  • Tutorial on Hudson, JUnit and Ant

    - by Grant Ronald
    Often when discussing ADF we often show the features for developing applications. However, writing applications is only one part.  Building in a team, integrating code, testing it...these are equally important to the success of the project.  If you would like to find out how features in JDeveloper can help you build, maintain, integrate and test your application then check out this tutorial.

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  • LINQ und ArcObjects

    - by Marko Apfel
    LINQ und ArcObjects Motivation LINQ1 (language integrated query) ist eine Komponente des Microsoft .NET Frameworks seit der Version 3.5. Es erlaubt eine SQL-ähnliche Abfrage zu verschiedenen Datenquellen wie SQL, XML u.v.m. Wie SQL auch, bietet LINQ dazu eine deklarative Notation der Problemlösung - d.h. man muss nicht im Detail beschreiben wie eine Aufgabe, sondern was überhaupt zu lösen ist. Das befreit den Entwickler abfrageseitig von fehleranfälligen Iterator-Konstrukten. Ideal wäre es natürlich auf diese Möglichkeiten auch in der ArcObjects-Programmierung mit Features zugreifen zu können. Denkbar wäre dann folgendes Konstrukt: var largeFeatures = from feature in features where (feature.GetValue("SHAPE_Area").ToDouble() > 3000) select feature; bzw. dessen Äquivalent als Lambda-Expression: var largeFeatures = features.Where(feature => (feature.GetValue("SHAPE_Area").ToDouble() > 3000)); Dazu muss ein entsprechender Provider zu Verfügung stehen, der die entsprechende Iterator-Logik managt. Dies ist leichter als man auf den ersten Blick denkt - man muss nur die gewünschten Entitäten als IEnumerable<IFeature> liefern. (Anm.: nicht wundern - die Methoden GetValue() und ToDouble() habe ich nebenbei als Erweiterungsmethoden deklariert.) Im Hintergrund baut LINQ selbständig eine Zustandsmaschine (state machine)2 auf deren Ausführung verzögert ist (deferred execution)3 - d.h. dass erst beim tatsächlichen Anfordern von Entitäten (foreach, Count(), ToList(), ..) eine Instanziierung und Verarbeitung stattfindet, obwohl die Zuweisung schon an ganz anderer Stelle erfolgte. Insbesondere bei mehrfacher Iteration durch die Entitäten reibt man sich bei den ersten Debuggings verwundert die Augen wenn der Ausführungszeiger wie von Geisterhand wieder in die Iterator-Logik springt. Realisierung Eine ganz knappe Logik zum Konstruieren von IEnumerable<IFeature> lässt sich mittels Durchlaufen eines IFeatureCursor realisieren. Dazu werden die einzelnen Feature mit yield ausgegeben. Der einfachen Verwendung wegen, habe ich die Logik in eine Erweiterungsmethode GetFeatures() für IFeatureClass aufgenommen: public static IEnumerable GetFeatures(this IFeatureClass featureClass, IQueryFilter queryFilter, RecyclingPolicy policy) { IFeatureCursor featureCursor = featureClass.Search(queryFilter, RecyclingPolicy.Recycle == policy); IFeature feature; while (null != (feature = featureCursor.NextFeature())) { yield return feature; } //this is skipped in unit tests with cursor-mock if (Marshal.IsComObject(featureCursor)) { Marshal.ReleaseComObject(featureCursor); } } Damit kann man sich nun ganz einfach die IEnumerable<IFeature> erzeugen lassen: IEnumerable features = _featureClass.GetFeatures(RecyclingPolicy.DoNotRecycle); Etwas aufpassen muss man bei der Verwendung des "Recycling-Cursors". Nach einer verzögerten Ausführung darf im selben Kontext nicht erneut über die Features iteriert werden. In diesem Fall wird nämlich nur noch der Inhalt des letzten (recycelten) Features geliefert und alle Features sind innerhalb der Menge gleich. Kritisch würde daher das Konstrukt largeFeatures.ToList(). ForEach(feature => Debug.WriteLine(feature.OID)); weil ToList() schon einmal durch die Liste iteriert und der Cursor somit einmal durch die Features bewegt wurde. Die Erweiterungsmethode ForEach liefert dann immer dasselbe Feature. In derartigen Situationen darf also kein Cursor mit Recycling verwendet werden. Ein mehrfaches Ausführen von foreach ist hingegen kein Problem weil dafür jedes Mal die Zustandsmaschine neu instanziiert wird und somit der Cursor neu durchlaufen wird – das ist die oben schon erwähnte Magie. Ausblick Nun kann man auch einen Schritt weiter gehen und ganz eigene Implementierungen für die Schnittstelle IEnumerable<IFeature> in Angriff nehmen. Dazu müssen nur die Methode und das Property zum Zugriff auf den Enumerator ausprogrammiert werden. Im Enumerator selbst veranlasst man in der Reset()-Methode das erneute Ausführen der Suche – dazu übergibt man beispielsweise ein entsprechendes Delegate in den Konstruktur: new FeatureEnumerator( _featureClass, featureClass => featureClass.Search(_filter, isRecyclingCursor)); und ruft dieses beim Reset auf: public void Reset() {     _featureCursor = _resetCursor(_t); } Auf diese Art und Weise können Enumeratoren für völlig verschiedene Szenarien implementiert werden, die clientseitig restlos identisch nach obigen Schema verwendet werden. Damit verschmelzen Cursors, SelectionSets u.s.w. zu einer einzigen Materie und die Wiederverwendbarkeit von Code steigt immens. Obendrein lässt sich ein IEnumerable in automatisierten Unit-Tests sehr einfach mocken - ein großer Schritt in Richtung höherer Software-Qualität.4 Fazit Nichtsdestotrotz ist Vorsicht mit diesen Konstrukten in performance-relevante Abfragen geboten. Dadurch dass im Hintergrund eine Zustandsmaschine verwalten wird, entsteht einiges an Overhead dessen Verarbeitung zusätzliche Zeit kostet - ca. 20 bis 100 Prozent. Darüber hinaus ist auch das Arbeiten ohne Recycling schnell ein Performance-Gap. Allerdings ist deklarativer LINQ-Code viel eleganter, fehlerfreier und wartungsfreundlicher als das manuelle Iterieren, Vergleichen und Aufbauen einer Ergebnisliste. Der Code-Umfang verringert sich erfahrungsgemäß im Schnitt um 75 bis 90 Prozent! Dafür warte ich gerne ein paar Millisekunden länger. Wie so oft muss abgewogen werden zwischen Wartbarkeit und Performance - wobei für mich Wartbarkeit zunehmend an Priorität gewinnt. Zumeist ist sowieso nicht der Code sondern der Anwender die Bremse im Prozess. Demo-Quellcode support.esri.de   [1] Wikipedia: LINQ http://de.wikipedia.org/wiki/LINQ [2] Wikipedia: Zustandsmaschine http://de.wikipedia.org/wiki/Endlicher_Automat [3] Charlie Calverts Blog: LINQ and Deferred Execution http://blogs.msdn.com/b/charlie/archive/2007/12/09/deferred-execution.aspx [4] Clean Code Developer - gelber Grad/Automatisierte Unit Tests http://www.clean-code-developer.de/Gelber-Grad.ashx#Automatisierte_Unit_Tests_8

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  • Is it worth moving from stored procedures to linq ?

    - by Josef
    I'm looking at standardizing programming in an organisaiton. Half uses stored procedures and the other half Linq. From what i've read there is still some debate going on on this topic. My concern is that MS is trying to slip in it's own proprietry query language 'linq' to make SQL redundant. If a few years back microsoft had tried to win customers from oracle and sybase with their MSSQL database and stated that it didn't use SQL by their own proprietry query langues ie linq. I doubt many would have switched. I believe that is exactly what is happening now by introducting it into the applicaiton business layer. I have used MS for many years but there is one gripe that I have with them and that is that they change their direction a lot. By a lot I mean new releases of .net, silverlight etc are more than 30% different from previous version. So by the time you become productive a new release is on the way. As things stand now a web developer using .net would need to know either vb.net or c#, xml, xaml,javascript,html, sql and now linq. That doesn't make for good productivity in my books. My concern is that once we all start using linq MS will start changing it between releases. and it will become an ever changing landscape. I believe that 'linq to sql' has already been deprecated. At leas with SQL we are dealing with a more stable and standardized language. Are we looking at a programming revolution or a marketing campaign? As far as I know other languages like Cobol have stayed the same for years. A cobol program from 20 years ago could pick up todays code and start working on it. Could a Vb3 person work on a modern .net web app ? Would these large changes need to be made if the underlying original foundation had been sound ? I worry about following MS shaking roadmap with it's deadends and double backs. are there any architects out there who feel the same ? regards Josef

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  • LINQ to SQL Could not find key member. Only fails on server.

    - by Adam Carr
    I have a scenario where I am inheriting from an abstract class in my partial linq to sql auto generated class implementation. My base abstract class has an abstract property called ID which I have flagged inside my LINQ to SQL model with the instance modifier override. This works fine locally without any issues. I have also done some development on another machine and it works fine there too (both in VS2008 and using Subversion). I am running CI with TeamCity and the build succeeds and deploys as desired. The problem is when the server tries to hit the database for the first time via the LINQ to SQL data context, it generates the following error. "Could not find key member 'Id' of key 'Id' on type 'CustomType'. The key may be wrong or the field or property on 'CustomType' has changed names." I have tried changing my configuration by not implementing the Id field in my base class but this still fails. Why does it work on both of my DEV machines but not on the server? I am using LINQ to SQL in another project that runs on this server just fine. FYI: LINQ to SQL, SQL 2008, .NET 3.5, SERVER 2008, IIS 7.0 UPDATE I have gone back and added the same table a second time in the same data model but without a base class and have then displayed the results from that table and got no errors. This tells me it has something to do with my base abstract class and the need to flag a property on one of my linq to sql model classes (that belongs to a key relationship) with the instance modifier of override. No answer to this yet but am getting closer. UPDATE I have fixed my issue by simply changing my approach to my problem but I am still interested in why this doesn't work. I created a new WinSrv2008 VPC and patched it, deployed a pre-built version of my site to it and still got the same error. I now assume the issue is like what the person said here, a dependency issue with VS2008. My question is what or what? Will install VS2008 on the VPC to see if it works after that.

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  • Dump Linq-To-Sql now that Entity Framework 4.0 has been released?

    - by DanM
    The relative simplicity of Linq-To-Sql as well as all the criticism leveled at version 1 of Entity Framework (especially, the vote of no confidence) convinced me to go with Linq-To-Sql "for the time being". Now that EF 4.0 is out, I wonder if it's time to start migrating over to it. Questions: What are the pros and cons of EF 4.0 relative to Linq-To-Sql? Is EF 4.0 finally ready for prime time? Is now the time to switch over?

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  • Linq to Sql, Repositories, and Asp.Net MVC ViewData: How to remove redundancy?

    - by Dr. Zim
    Linq to SQL creates objects which are IQueryable and full of relations. Html Helpers require specific interface objects like IEnumerable<SelectListItem>. What I think could happen: Reuse the objects from Linq to SQL without all the baggage, i.e., return Pocos from the Linq to SQL objects without additional Domain Model classes? Extract objects that easily convert to (or are) Html helper objects like the SelectListItem enumeration? Is there any way to do this without breaking separation of concerns? Some neat oop trick to bridge the needs? For example, if this were within a repository, the SelectListItem wouldn't be there. The select new is a nice way to cut out an object from the Linq to SQL without the baggage but it's still referencing a class that shouldn't be referenced: IEnumerable<SelectListItem> result = (from record in db.table select new SelectListItem { Selected = record.selected, Text= record.Text, Value= record.Value } ).AsEnumerable();

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  • Is it worth a try LINQ to SQL as a beginner to an ORM?

    - by Pandiya Chendur
    Thus far used sql server stored procedures for all my web applications... Now thought of moving to an ORM... I would like to ask SO users about LINQ to SQL Is Linq to sql worth a try as a beginner to an ORM? or should i look for some others... Any suggestion... EDIT: I have a sql server 2005 database with all tables.... How to use this db with Linq to sql?

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  • Can I have Entity Framework and Linq-to-SQL run together?

    - by Shnitzel
    Hi, I'd like to know if it's possible to have both Linq-to-SQL and Entity Framework running side-by-side. Our current configuration is Linq-to-SQL and we'd like to eventually move to EF. But there's just too much going on in the Linq-to-SQL side right now and we'd like to do it in phases. so any chance we can just start writing new stuff in entity framework but leave the older stuff running as is? And is it worth it? Thanks!

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  • Why SELECT N + 1 with no foreign keys and LINQ?

    - by Daniel Flöijer
    I have a database that unfortunately have no real foreign keys (I plan to add this later, but prefer not to do it right now to make migration easier). I have manually written domain objects that map to the database to set up relationships (following this tutorial http://www.codeproject.com/Articles/43025/A-LINQ-Tutorial-Mapping-Tables-to-Objects), and I've finally gotten the code to run properly. However, I've noticed I now have the SELECT N + 1 problem. Instead of selecting all Product's they're selected one by one with this SQL: SELECT [t0].[id] AS [ProductID], [t0].[Name], [t0].[info] AS [Description] FROM [products] AS [t0] WHERE [t0].[id] = @p0 -- @p0: Input Int (Size = -1; Prec = 0; Scale = 0) [65] Controller: public ViewResult List(string category, int page = 1) { var cat = categoriesRepository.Categories.SelectMany(c => c.LocalizedCategories).Where(lc => lc.CountryID == 1).First(lc => lc.Name == category).Category; var productsToShow = cat.Products; var viewModel = new ProductsListViewModel { Products = productsToShow.Skip((page - 1) * PageSize).Take(PageSize).ToList(), PagingInfo = new PagingInfo { CurrentPage = page, ItemsPerPage = PageSize, TotalItems = productsToShow.Count() }, CurrentCategory = cat }; return View("List", viewModel); } Since I wasn't sure if my LINQ expression was correct I tried to just use this but I still got N+1: var cat = categoriesRepository.Categories.First(); Domain objects: [Table(Name = "products")] public class Product { [Column(Name = "id", IsPrimaryKey = true, IsDbGenerated = true, AutoSync = AutoSync.OnInsert)] public int ProductID { get; set; } [Column] public string Name { get; set; } [Column(Name = "info")] public string Description { get; set; } private EntitySet<ProductCategory> _productCategories = new EntitySet<ProductCategory>(); [System.Data.Linq.Mapping.Association(Storage = "_productCategories", OtherKey = "productId", ThisKey = "ProductID")] private ICollection<ProductCategory> ProductCategories { get { return _productCategories; } set { _productCategories.Assign(value); } } public ICollection<Category> Categories { get { return (from pc in ProductCategories select pc.Category).ToList(); } } } [Table(Name = "products_menu")] class ProductCategory { [Column(IsPrimaryKey = true, Name = "products_id")] private int productId; private EntityRef<Product> _product = new EntityRef<Product>(); [System.Data.Linq.Mapping.Association(Storage = "_product", ThisKey = "productId")] public Product Product { get { return _product.Entity; } set { _product.Entity = value; } } [Column(IsPrimaryKey = true, Name = "products_types_id")] private int categoryId; private EntityRef<Category> _category = new EntityRef<Category>(); [System.Data.Linq.Mapping.Association(Storage = "_category", ThisKey = "categoryId")] public Category Category { get { return _category.Entity; } set { _category.Entity = value; } } } [Table(Name = "products_types")] public class Category { [Column(Name = "id", IsPrimaryKey = true, IsDbGenerated = true, AutoSync = AutoSync.OnInsert)] public int CategoryID { get; set; } private EntitySet<ProductCategory> _productCategories = new EntitySet<ProductCategory>(); [System.Data.Linq.Mapping.Association(Storage = "_productCategories", OtherKey = "categoryId", ThisKey = "CategoryID")] private ICollection<ProductCategory> ProductCategories { get { return _productCategories; } set { _productCategories.Assign(value); } } public ICollection<Product> Products { get { return (from pc in ProductCategories select pc.Product).ToList(); } } private EntitySet<LocalizedCategory> _LocalizedCategories = new EntitySet<LocalizedCategory>(); [System.Data.Linq.Mapping.Association(Storage = "_LocalizedCategories", OtherKey = "CategoryID")] public ICollection<LocalizedCategory> LocalizedCategories { get { return _LocalizedCategories; } set { _LocalizedCategories.Assign(value); } } } [Table(Name = "products_types_localized")] public class LocalizedCategory { [Column(Name = "id", IsPrimaryKey = true, IsDbGenerated = true, AutoSync = AutoSync.OnInsert)] public int LocalizedCategoryID { get; set; } [Column(Name = "products_types_id")] private int CategoryID; private EntityRef<Category> _Category = new EntityRef<Category>(); [System.Data.Linq.Mapping.Association(Storage = "_Category", ThisKey = "CategoryID")] public Category Category { get { return _Category.Entity; } set { _Category.Entity = value; } } [Column(Name = "country_id")] public int CountryID { get; set; } [Column] public string Name { get; set; } } I've tried to comment out everything from my View, so nothing there seems to influence this. The ViewModel is as simple as it looks, so shouldn't be anything there. When reading this ( http://www.hookedonlinq.com/LinqToSQL5MinuteOVerview.ashx) I started suspecting it might be because I have no real foreign keys in the database and that I might need to use manual joins in my code. Is that correct? How would I go about it? Should I remove my mapping code from my domain model or is it something that I need to add/change to it? Note: I've stripped parts of the code out that I don't think is relevant to make it cleaner for this question. Please let me know if something is missing.

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  • Can I use Linq-to-xml to persist my object state without having to use/know Xpath & XSD Syntax?

    - by Greg
    Hi, Can I use Linq-to-xml to persist my object state without having to use/know Xpath & XSD Syntax? ie. really looking for simple but flexible way to persist a graph of object data (e.g. have say 2 or 3 classes with associations) - if Linq-to-xml were as simple as saying "persist this graph to XML", and then you could also query it via Linq, or load it into memory again/change/then re-save to the xml file.

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  • How can I do this Aggrigate, group by, in query in LINQ?

    - by Ólafur Waage
    Please do not give me a full working example, I want to know how this is done rather than to get some code I can copy paste This is the query I need, and can't for the life of me create it in LINQ. SELECT * FROM dbo.Schedules s, dbo.Videos v WHERE s.VideoID = v.ID AND s.ID IN ( SELECT MAX(ID) FROM dbo.Schedules WHERE ChannelID = 1 GROUP BY VideoID ) ORDER BY v.Rating DESC, s.StartTime DESC I have the "IN" query in LINQ I think, it's something like this var uniqueList = from schedule in db.Schedules where schedule.ChannelID == channelID group schedule by schedule.VideoID into s select new { id = s.Max(i => i.ID) }; It is possibly wrong, but now I can not check in another query for this in a where clause uniqueList.Contains(schedule.ID) There is possibly a better way to write this query, if you have any idea I would love some hints. I get this error and it's not making much sense. The type arguments for method 'System.Linq.Queryable.Contains(System.Linq.IQueryable, TSource)' cannot be inferred from the usage. Try specifying the type arguments explicitly.

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  • What guarantees are there on the run-time complexity (Big-O) of LINQ methods?

    - by tzaman
    I've recently started using LINQ quite a bit, and I haven't really seen any mention of run-time complexity for any of the LINQ methods. Obviously, there are many factors at play here, so let's restrict the discussion to the plain IEnumerable LINQ-to-Objects provider. Further, let's assume that any Func passed in as a selector / mutator / etc. is a cheap O(1) operation. It seems obvious that all the single-pass operations (Select, Where, Count, Take/Skip, Any/All, etc.) will be O(n), since they only need to walk the sequence once; although even this is subject to laziness. Things are murkier for the more complex operations; the set-like operators (Union, Distinct, Except, etc.) work using GetHashCode by default (afaik), so it seems reasonable to assume they're using a hash-table internally, making these operations O(n) as well, in general. What about the versions that use an IEqualityComparer? OrderBy would need a sort, so most likely we're looking at O(n log n). What if it's already sorted? How about if I say OrderBy().ThenBy() and provide the same key to both? I could see GroupBy (and Join) using either sorting, or hashing. Which is it? Contains would be O(n) on a List, but O(1) on a HashSet - does LINQ check the underlying container to see if it can speed things up? And the real question - so far, I've been taking it on faith that the operations are performant. However, can I bank on that? STL containers, for example, clearly specify the complexity of every operation. Are there any similar guarantees on LINQ performance in the .NET library specification?

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  • LINQ to Twitter v2.1.09 Released

    - by Joe Mayo
    Originally posted on: http://geekswithblogs.net/WinAZ/archive/2013/10/15/linq-to-twitter-v2.1.09-released.aspxToday, I released LINQ to Twitter v2.1.09. Here are important new changes. Bug Fixes This is primarily a bug fix release. Most notably, there were authentication problems in WinRT apps. This is now fixed. New Features One new feature is the addition of ApplicationOnlyAuthentication for WinRT. It is fully async.  Here’s how it works: var auth = new WinRtApplicationOnlyAuthorizer { Credentials = new InMemoryCredentials { ConsumerKey = "", ConsumerSecret = "" } }; if (auth == null || !auth.IsAuthorized) { await auth.AuthorizeAsync(); } var twitterCtx = new TwitterContext(auth); (from search in twitterCtx.Search where search.Type == SearchType.Search && search.Query == SearchTextBox.Text select search) .MaterializedAsyncCallback( async response => await Dispatcher.RunAsync( CoreDispatcherPriority.Normal, async () => { Search searchResponse = response.State.Single(); string message = string.Format( "Search returned {0} statuses", searchResponse.Statuses.Count); await new MessageDialog(message, "Search Complete").ShowAsync(); })); It’s called the WinRtApplicationOnlyAuthorizer. You only need two tokens, ConsumerKey and ConsumerSecret, which come from your Twitter API application settings page. Note: You need a Twitter Application, which you can create at https://dev.twitter.com/. The MaterializedAsyncCallback materializes your query and handles the response. I put everything together in a lambda for demonstration purposes, but you can always replace the callback with a handler of type Action<TwitterAsyncResponse<IEnumerable<T>>>, where T is Search for this example. On the Horizon The next version of LINQ to Twitter is in development. I discussed it at LINQ to Twitter Async. This isn’t complete, but you can download the source code at the LINQ to Twitter site on CodePlex. I’ve competed all the spikes for what I thought would be the hard parts and now have prototypes of queries and commands working. This would be a good time to provide feedback if there are features in the current version that you think could be improved. The current driving forces for the next version will be async and PCL.   @JoeMayo

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  • Oracle R Enterprise Tutorial Series on Oracle Learning Library

    - by mhornick
    Oracle Server Technologies Curriculum has just released the Oracle R Enterprise Tutorial Series, which is publicly available on Oracle Learning Library (OLL). This 8 part interactive lecture series with review sessions covers Oracle R Enterprise 1.1 and an introduction to Oracle R Connector for Hadoop 1.1: Introducing Oracle R Enterprise Getting Started with ORE R Language Basics Producing Graphs in R The ORE Transparency Layer ORE Embedded R Scripts: R Interface ORE Embedded R Scripts: SQL Interface Using the Oracle R Connector for Hadoop We encourage you to download Oracle software for evaluation from the Oracle Technology Network. See these links for R-related software: Oracle R Distribution, Oracle R Enterprise, ROracle, Oracle R Connector for Hadoop.  As always, we welcome comments and questions on the Oracle R Forum.

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  • Good book or tutorial for learning how to apply integration methods

    - by Cumatru
    I'm looking to animate a graph layout using edges as springs and nodes as weights ( a node with more links will have a bigger weight ). I'm not capable of wrapping my head around the usage of mathematical and physics relations in my application. As far as i read, Runge Kutta 4 ( preferably ) or Verlet will be a good choice, but i have problems with understanding how they really work, and what physics equations should i apply. If i can't understand them, i can't use them. I'm looking for a book or a tutorial which describe the things that i need.

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  • C++ Game Engine Book/Tutorial/Anything recent?

    - by TheNoob
    Before I get flamed, please understand that I have been looking for a while now. Yes, I have found a good amount of game engine tutorials...except filled with errors, out of date syntax, missing crucial information, and so on. Is there anywhere with a recent tutorial, or a book, anything at all? I'm not asking for an opinion in graphics API's, just a point in the right direction to get started on game engine development. I just want to make it clear, I have googled/stacked like crazy. Any help appreciated. Thank you.

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  • What is the right license for tutorial source code ?

    - by devdude
    Putting sourcecode from tutorials or books online requires the author to add some kind of disclaimer or license (otherwise people would use it make lots of $$$ or break a power plant IT control system and sue you as author). But what is the right license or disclaimer statement ? Can I use BSD license with ... IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,... We are talking about tutorials ! Released to teach and share knowledge. Or do I need to follow the (potentially different) licenses of the libraries I use ? Might be insignificant now but I feel we will face a license hunt in "public" sourcecode (aka OSS) in future, similar to companies/lawyers currently crawling the web for pictures with wrong copyright statement or infringing their IP (and suing someone using a picture in a personal blog,etc..).

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  • C# 4.0 Optional/Named Parameters Beginner&rsquo;s Tutorial

    - by mbcrump
    One of the interesting features of C# 4.0 is for both named and optional arguments.  They are often very useful together, but are quite actually two different things.  Optional arguments gives us the ability to omit arguments to method invocations. Named arguments allows us to specify the arguments by name instead of by position.  Code using the named parameters are often more readable than code relying on argument position.  These features were long overdue, especially in regards to COM interop. Below, I have included some examples to help you understand them more in depth. Please remember to target the .NET 4 Framework when trying these samples. Code Snippet using System;   namespace ConsoleApplication3 {     class Program     {         static void Main(string[] args)         {               //C# 4.0 Optional/Named Parameters Tutorial               Foo();                              //Prints to the console | Return Nothing 0             Foo("Print Something");             //Prints to the console | Print Something 0             Foo("Print Something", 1);          //Prints to the console | Print Something 1             Foo(x: "Print Something", i: 5);    //Prints to the console | Print Something 5             Foo(i: 5, x: "Print Something");    //Prints to the console | Print Something 5             Foo("Print Something", i: 5);       //Prints to the console | Print Something 5             Foo2(i3: 77);                       //Prints to the console | 77         //  Foo(x:"Print Something", 5);        //Positional parameters must come before named arguments. This will error out.             Console.Read();         }           static void Foo(string x = "Return Nothing", int i = 0)         {             Console.WriteLine(x + " " + i + Environment.NewLine);         }           static void Foo2(int i = 1, int i2 = 2, int i3 = 3, int i4 = 4)         {             Console.WriteLine(i3);         }     } }

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  • Farseer tutorial for the absolute beginners

    - by Bil Simser
    This post is inspired (and somewhat a direct copy) of a couple of posts Emanuele Feronato wrote back in 2009 about Box2D (his tutorial was ActionScript 3 based for Box2D, this is C# XNA for the Farseer Physics Engine). Here’s what we’re building: What is Farseer The Farseer Physics Engine is a collision detection system with realistic physics responses to help you easily create simple hobby games or complex simulation systems. Farseer was built as a .NET version of Box2D (based on the Box2D.XNA port of Box2D). While the constructs and syntax has changed over the years, the principles remain the same. This tutorial will walk you through exactly what Emanuele create for Flash but we’ll be doing it using C#, XNA and the Windows Phone platform. The first step is to download the library from its home on CodePlex. If you have NuGet installed, you can install the library itself using the NuGet package that but we’ll also be using some code from the Samples source that can only be obtained by downloading the library. Once you download and unpacked the zip file into a folder and open the solution, this is what you will get: The Samples XNA WP7 project (and content) have all the demos for Farseer. There’s a wealth of info here and great examples to look at to learn. The Farseer Physics XNA WP7 project contains the core libraries that do all the work. DebugView XNA contains an XNA-ready class to let you view debug data and information in the game draw loop (which you can copy into your project or build the source and reference the assembly). The downloaded version has to be compiled as it’s only available in source format so you can do that now if you want (open the solution file and rebuild everything). If you’re using the NuGet package you can just install that. We only need the core library and we’ll be copying in some code from the samples later. Your first Farseer experiment Start Visual Studio and create a new project using the Windows Phone template can call it whatever you want. It’s time to edit Game1.cs 1 public class Game1 : Game 2 { 3 private readonly GraphicsDeviceManager _graphics; 4 private DebugViewXNA _debugView; 5 private Body _floor; 6 private SpriteBatch _spriteBatch; 7 private float _timer; 8 private World _world; 9 10 public Game1() 11 { 12 _graphics = new GraphicsDeviceManager(this) 13 { 14 PreferredBackBufferHeight = 800, 15 PreferredBackBufferWidth = 480, 16 IsFullScreen = true 17 }; 18 19 Content.RootDirectory = "Content"; 20 21 // Frame rate is 30 fps by default for Windows Phone. 22 TargetElapsedTime = TimeSpan.FromTicks(333333); 23 24 // Extend battery life under lock. 25 InactiveSleepTime = TimeSpan.FromSeconds(1); 26 } 27 28 protected override void LoadContent() 29 { 30 // Create a new SpriteBatch, which can be used to draw textures. 31 _spriteBatch = new SpriteBatch(_graphics.GraphicsDevice); 32 33 // Load our font (DebugViewXNA needs it for the DebugPanel) 34 Content.Load<SpriteFont>("font"); 35 36 // Create our World with a gravity of 10 vertical units 37 if (_world == null) 38 { 39 _world = new World(Vector2.UnitY*10); 40 } 41 else 42 { 43 _world.Clear(); 44 } 45 46 if (_debugView == null) 47 { 48 _debugView = new DebugViewXNA(_world); 49 50 // default is shape, controller, joints 51 // we just want shapes to display 52 _debugView.RemoveFlags(DebugViewFlags.Controllers); 53 _debugView.RemoveFlags(DebugViewFlags.Joint); 54 55 _debugView.LoadContent(GraphicsDevice, Content); 56 } 57 58 // Create and position our floor 59 _floor = BodyFactory.CreateRectangle( 60 _world, 61 ConvertUnits.ToSimUnits(480), 62 ConvertUnits.ToSimUnits(50), 63 10f); 64 _floor.Position = ConvertUnits.ToSimUnits(240, 775); 65 _floor.IsStatic = true; 66 _floor.Restitution = 0.2f; 67 _floor.Friction = 0.2f; 68 } 69 70 protected override void Update(GameTime gameTime) 71 { 72 // Allows the game to exit 73 if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed) 74 Exit(); 75 76 // Create a random box every second 77 _timer += (float) gameTime.ElapsedGameTime.TotalSeconds; 78 if (_timer >= 1.0f) 79 { 80 // Reset our timer 81 _timer = 0f; 82 83 // Determine a random size for each box 84 var random = new Random(); 85 var width = random.Next(20, 100); 86 var height = random.Next(20, 100); 87 88 // Create it and store the size in the user data 89 var box = BodyFactory.CreateRectangle( 90 _world, 91 ConvertUnits.ToSimUnits(width), 92 ConvertUnits.ToSimUnits(height), 93 10f, 94 new Point(width, height)); 95 96 box.BodyType = BodyType.Dynamic; 97 box.Restitution = 0.2f; 98 box.Friction = 0.2f; 99 100 // Randomly pick a location along the top to drop it from 101 box.Position = ConvertUnits.ToSimUnits(random.Next(50, 400), 0); 102 } 103 104 // Advance all the elements in the world 105 _world.Step(Math.Min((float) gameTime.ElapsedGameTime.TotalMilliseconds*0.001f, (1f/30f))); 106 107 // Clean up any boxes that have fallen offscreen 108 foreach (var box in from box in _world.BodyList 109 let pos = ConvertUnits.ToDisplayUnits(box.Position) 110 where pos.Y > _graphics.GraphicsDevice.Viewport.Height 111 select box) 112 { 113 _world.RemoveBody(box); 114 } 115 116 base.Update(gameTime); 117 } 118 119 protected override void Draw(GameTime gameTime) 120 { 121 GraphicsDevice.Clear(Color.FromNonPremultiplied(51, 51, 51, 255)); 122 123 _spriteBatch.Begin(); 124 125 var projection = Matrix.CreateOrthographicOffCenter( 126 0f, 127 ConvertUnits.ToSimUnits(_graphics.GraphicsDevice.Viewport.Width), 128 ConvertUnits.ToSimUnits(_graphics.GraphicsDevice.Viewport.Height), 0f, 0f, 129 1f); 130 _debugView.RenderDebugData(ref projection); 131 132 _spriteBatch.End(); 133 134 base.Draw(gameTime); 135 } 136 } 137 Lines 4: Declare the debug view we’ll use for rendering (more on that later). Lines 8: Declare _world variable of type class World. World is the main object to interact with the Farseer engine. It stores all the joints and bodies, and is responsible for stepping through the simulation. Lines 12-17: Create the graphics device we’ll be rendering on. This is an XNA component and we’re just setting it to be the same size as the phone and toggling it to be full screen (no system tray). Lines 34: We create a SpriteFont here by adding it to the project. It’s called “font” because that’s what the DebugView uses but you can name it whatever you want (and if you’re not using DebugView for your production app you might have several fonts). Lines 37-44: We create the physics environment that Farseer uses to contain all the objects by specifying it here. We’re using Vector2.UnitY*10 to represent the gravity to be used in the environment. In other words, 10 units going in a downward motion. Lines 46-56: We create the DebugViewXNA here. This is copied from the […] from the code you downloaded and provides the ability to render all entities onto the screen. In a production release you’ll be doing the rendering yourself of each object but we cheat a bit for the demo and let the DebugView do it for us. The other thing it can provide is to render out a panel of debugging information while the simulation is going on. This is useful in tracking down objects, figuring out how something works, or just keeping track of what’s in the engine. Lines 49-67: Here we create a rigid body (Farseer only supports rigid bodies) to represent the floor that we’ll drop objects onto. We create it by using one of the Farseer factories and specifying the width and height. The ConvertUnits class is copied from the samples code as-is and lets us toggle between display units (pixels) and simulation units (usually metres). We’re creating a floor that’s 480 pixels wide and 50 pixels high (converting them to SimUnits for the engine to understand). We also position it near the bottom of the screen. Values are in metres and when specifying values they refer to the centre of the body object. Lines 77-78: The game Update method fires 30 times a second, too fast to be creating objects this quickly. So we use a variable to track the elapsed seconds since the last update, accumulate that value, then create a new box to drop when 1 second has passed. Lines 89-94: We create a box the same way we created our floor (coming up with a random width and height for the box). Lines 96-101: We set the box to be Dynamic (rather than Static like the floor object) and position it somewhere along the top of the screen. And now you created the world. Gravity does the rest and the boxes fall to the ground. Here’s the result: Farseer Physics Engine Demo using XNA Lines 105: We must update the world at every frame. We do this with the Step method which takes in the time interval. [more] Lines 108-114: Body objects are added to the world but never automatically removed (because Farseer doesn’t know about the display world, it has no idea if an item is on the screen or not). Here we just loop through all the entities and anything that’s dropped off the screen (below the bottom) gets removed from the World. This keeps our entity count down (the simulation never has more than 30 or 40 objects in the world no matter how long you run it for). Too many entities and the app will grind to a halt. Lines 125-130: Farseer knows nothing about the UI so that’s entirely up to you as to how to draw things. Farseer is just tracking the objects and moving them around using the physics engine and it’s rules. You’ll still use XNA to draw items (using the SpriteBatch.Draw method) so you can load up your usual textures and draw items and pirates and dancing zombies all over the screen. Instead in this demo we’re going to cheat a little. In the sample code for Farseer you can download there’s a project called DebugView XNA. This project contains the DebugViewXNA class which just handles iterating through all the bodies in the world and drawing the shapes. So we call the RenderDebugData method here of that class to draw everything correctly. In the case of this demo, we just want to draw Shapes so take a look at the source code for the DebugViewXNA class as to how it extracts all the vertices for the shapes created (in this case simple boxes) and draws them. You’ll learn a *lot* about how Farseer works just by looking at this class. That’s it, that’s all. Simple huh? Hope you enjoy the code and library. Physics is hard and requires some math skills to really grok. The Farseer Physics Engine makes it pretty easy to get up and running and start building games. In future posts we’ll get more in-depth with things you can do with the engine so this is just the beginning. Enjoy!

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  • XML Rules Engine and Validation Tutorial with NIEM

    - by drrwebber
    Our new XML Validation Framework tutorial video is now available. See how to easily integrate code-free adaptive XML validation services into your web services using the Java CAMV validation engine. CAMV allows you to build fault tolerant content checking with XPath that optionally use SQL data lookups. This can provide warnings as well as error conditions to tailor your validation layer to exactly meet your business application needs. Also available is developing test suites using Apache ANT scripting of validations.  This allows a community to share sets of conformance checking test and tools . On the technical XML side the video introduces XPath validation rules and illustrates and the concepts of XML content and structure validation. CAM validation templates allow contextual parameter driven dynamic validation services to be implemented compared to using a static and brittle XSD schema approach.The SQL table lookup and code list validation are discussed and examples presented.Features are highlighted along with a demonstration of the interactive generation of actual live XML data from a SQL data store and then validation processing complete with errors and warnings detection.The presentation provides a primer for developing web service XML validation and integration into a SOA approach along with examples and resources. Also alignment with the NIEM IEPD process for interoperable information exchanges is discussed along with NIEM rules services.The CAMV engine is a high performance scalable Java component for rapidly implementing code-free validation services and methods. CAMV is a next generation WYSIWYG approach that builds from older Schematron coding based interpretative runtime tools and provides a simpler declarative metaphor for rules definition. See: http://www.youtube.com/user/TheCAMeditor

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  • A Trio of Presentations: Little Wonders, StyleCop, and LINQ/Lambdas

    - by James Michael Hare
    This week is a busy week for me.  First of all I’m giving another presentation on a LINQ/Lambda primer for the rest of the developers in my company.  Of Lambdas and LINQ View more presentations from BlackRabbitCoder Then this Saturday the 25th of June I’ll be reprising my Little Wonders presentation for the Kansas City Developers Camp.  If you are in the area I highly recommend attending and seeing the other great presentations as well.  Their link is here. Little Wonders View more presentations from BlackRabbitCoder Finally, this Monday the 27th I’ll be speaking at the Saint Louis .NET Users group, giving my Automating Code Standards Using StyleCop and FxCop presentation.  If you are in the Saint Louis area stop by!  There’s two other simultaneous presentations as well if they’re more suited to your interests.  The link for the SLDNUG is here. Automating C# Coding Standards using StyleCop and FxCop View more presentations from BlackRabbitCoder Tweet Technorati Tags: C#,.NET,LINQ,Lambda,StyleCop,FxCop,Little Wonders

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  • Macro to Add using System.Linq

    - by Aligned
    I have Visual Studio 2010 setup to remove and sort settings on save with the Power Commands extensions. This is great, but sometimes it removes the using System.Linq at the top. I also find myself scrolling to the top to add the using when I first add System.Linq. So I wrote a quick macro to do it for me. Sub AddUsingLinq()        DTE.ActiveDocument.Selection.StartOfDocument()        DTE.ActiveDocument.Selection.StartOfLine(vsStartOfLineOptions.vsStartOfLineOptionsFirstText)        DTE.ActiveDocument.Selection.Text = "using System.Linq;"        DTE.ActiveDocument.Selection.NewLine()        DTE.ExecuteCommand("Edit.FormatDocument")        DTE.ExecuteCommand("Edit.RemoveAndSort")        DTE.ActiveDocument.Save() DTE.ExecuteCommand("View.NavigateBackward")    End SubHook this up to a shortcut (tools -> options -> keyboard, I chose ctrl + x, c) and you'll be moving faster than ever.

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  • Entity Framework 4.0: Optimal and horrible SQL

    - by DigiMortal
    Lately I had Entity Framework 4.0 session where I introduced new features of Entity Framework. During session I found out with audience how Entity Framework 4.0 can generate optimized SQL. After session I also showed guys one horrible example about how awful SQL can be generated by Entity Framework. In this posting I will cover both examples. Optimal SQL Before going to code take a look at following model. There is class called Event and I will use this class in my query. Here is the LINQ To Entities query that uses small anonymous type. var query = from e in _context.Events             select new { Id = e.Id, Title = e.Title }; Debug.WriteLine(((ObjectQuery)query).ToTraceString()); Running this code gives us the following SQL. SELECT      [Extent1].[event_id] AS [event_id],      [Extent1].[title] AS [title]  FROM [dbo].[events] AS [Extent1] This is really small – no additional fields in SELECT clause. Nice, isn’t it? Horrible SQL Ayende Rahien blog shows us darker side of Entiry Framework 4.0 queries. You can find comparison betwenn NHibernate, LINQ To SQL and LINQ To Entities from posting What happens behind the scenes: NHibernate, Linq to SQL, Entity Framework scenario analysis. In this posting I will show you the resulting query and let you think how much better it can be done. Well, it is not something we want to see running in our servers. I hope that EF team improves generated SQL to acceptable level before Visual Studio 2010 is released. There is also morale of this example: you should always check out the queries that O/R-mapper generates. Behind the curtains it may silently generate queries that perform badly and in this case you need to optimize you data querying strategy. Conclusion Entity Framework 4.0 is new product with a lot of new features and it is clear that not everything is 100% super in its first release. But it still great step forward and I hope that on 12.04.2010 we have new promising O/R-mapper available to use in our projects. If you want to read more about Entity Framework 4.0 and Visual Studio 2010 then please feel free to follow this link to list of my Visual Studio 2010 and .NET Framework 4.0 postings.

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  • Getting the first result from a LINQ query - why does ElementAt<T>(0) fails when First<T>() succeeds

    - by Mr Roys
    I have a method AddStudent() which looks for a student with the same name and returns an existing student from the database if there is a student with the same name, otherwise it creates a new student and adds it to the database. I'm curious why se = students.First<StudentEntity>(); succeeds when se = students.ElementAt<StudentEntity>(0); fails when I try to get the first result from the LINQ query. Aren't the two methods the same? The full code for the method is shown below. public Student AddStudent(string name) { using (SchoolEntities db = new SchoolEntities()) { // find student with same name via LINQ var students = from s in db.StudentEntitySet where s.name == name select s; StudentEntity se = default(StudentEntity); // if student with the same name is already present, return // that student if (students.Count<StudentEntity>() > 0) { // if i use ElementAt, if fails with a "LINQ to Entities does not // recognize the method 'StudentEntity ElementAt[StudentEntity] // (System.Linq.IQueryable`1[StudentEntity], Int32)' method, // and this method cannot be translated into a store expression.", // but not when I use First. Why? // se = students.ElementAt<StudentEntity>(0); se = students.First<StudentEntity>(); } else { // passing 0 for first parameter (id) since it's represented by // a BigInt IDENTITY field in the database so any value // doesn't matter. se = StudentEntity.CreateStudentEntity(0, name); db.AddToStudentEntitySet(se); db.SaveChanges(); } // create a Student object from the Entity object return new Student(se); } } Thanks!

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