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  • ARM TechCON 2013 presentation: Java SE 8 Compact Profiles

    - by hinkmond
    I'll be giving a technical session presentation at ARM TechCON 2013 this Wed. 10/30 @ 11:30am. So if you are in Santa Clara, Calif. come over to the conference and hear me present on this fun-filled topic! See: Java SE 8 Compact Profiles Here's a quote: Java SE 8 has a new Compact Profiles feature that allows for three new specification–compliant subsets of Java SE 8 APIs. Compact Profiles will enable the creation of Java SE 8 runtimes that support configurations that previously were possible only with the CDC version of J2ME... It's an important topic in today's mad, mad world of Embedded Development. You never want to develop in Java for small devices with your Compact Profiles. It's just not what you'd want! Hinkmond

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  • Recommended solutions for integrating iOS with .NET, at the service tier

    - by George
    I'm developing an application, in iOS, that is required to connect to my Windows Server to poll for new data, update, etc. As a seasoned C# developer, my first instinct is to start a new project in Visual Studio and select Web Service, letting my bias (and comfort level) dictate the service layer of my application. However, I don't want to be biased, and I don't base my decision on a service which I am very familiar with, at the cost of performance. I would like to know what other developers have had success using, and if there is a default standard for iOS service layer development? Are there protocols that are easier to consume than others within iOS? Better ones for the size and/or compression of data? Is there anything wrong with using SOAP? I know it's "big" in comparison to protocols like JSON.

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  • Welcome Windows Embedded Compact!

    - by Luca Calligaris
    Windows Embedded Compact 7 Public Community Technology Preview (Public CTP) is finally available for downloading: You need a Windows Live ID to log in and download the Public CTP Go to the Connection Directory, find Windows Embedded Compact 7 Public CTP and click on (apply) Download the Public CTP from the Compact 7 Public CTP program page In the next blog entries I'll try to address some of the new features of the new version of my favourite OS.

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  • migrating from struts2, looking for a new framework

    - by adhg
    We are supposed to start a relatively big project that will require lots of computation and analysis. Presentation (UI) for the end user is very crucial (graphs, tabels...) So far we've been using struts2. It's ok+. It has some drawbacks (specially if you work with tiles and all that XML) but if you get the lingo - you're ok. One option on the table is to continue using struts2 with jquery and all the other stuff that we've been doing for so long. Alternatively, I think we have an opportunity to learn something new and maybe a bit better then struts2. My question is this: Anyone has migrated from struts2 to something new and can share the experience. Or had some great experience witha particular java framework. Many thanks for any pointers.

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  • Framework licensing question [closed]

    - by nosarious
    I have a framework I have been developing but find myself being unable to work on it over the next year. I would like to make it open source in the interim to get others to use it and improve how it works. I would like to consider a licensing system that allows for multiple instances of the software for singular users (ie, a newspaper/magazine or zine hosting the code on their own). I would like to limit it from becoming the basis of a larger hosting service right now because it is intended to be part of a much larger hosting ecosystem which allows for create and share their work. Right now there is no license associated with it, which is why I am not posting a link here. Any help or suggestion on how to handle licensing this code for contributions and use would be appreciated, and if anyone would like to see examples or the github I would be happy to send it.

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  • Windows Embedded Compact 7

    - by Valter Minute
    This will be the official name of the new release of Windows CE. Windows Embedded Compact 7 is available as a public CTP and it already supports a wide range of CPUs and both the device emulator and VirtualPC emulated environments. So I’ll have to learn a new (and longer) name for my favorite OS… but I (and all my two readers!) will be able to test it as soon as the download from connect web site completes (I'm sorry for my readers, but you'll have to download it by yourselves). Here’s a link for the download (it's free but you’ll have to register on connect with a valid LiveId): https://connect.microsoft.com/windowsembeddedce Remember that this is still a beta (or “Community Technology Preview” if you speak marketing language) and so it’s better to not install it on your main development PC (or, at least, backup everything before installation) and that the features and performances you’ll get from this beta may not be the same ones of the final release of the OS. You can discover the new features of Windows Embedded Compact on the new “official” webpage on microsoft website: http://www.microsoft.com/windowsembedded/en-us/products/windowsce/compact7.mspx or on Olivier’s blog: http://blogs.msdn.com/b/obloch/archive/2010/06/01/windows-embedded-compact-7-announced-and-public-ctp-available.aspx I hope to be able to post some interesting content about Windows Embedded Compact 7 soon (and maybe be able to shorten it’s name in CE7 in my blog posts, when I'll ensure that both my readers are not worketing for Microsoft's marketing department …). Technorati Tags: "Windows Embedded Compact 7"

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  • Are there any advantages to using ASP.Net MVC 3 over Ruby On Rails for existing businesses? [closed]

    - by user786621
    Possible Duplicate: What ASP.NET MVC can do and Ruby on Rails can't? I've been hearing a lot of good press about Ruby On Rails but I'm having a hard time finding much information on the advantages of using ASP.Net MVC 3 over RoR, yet I see many existing businesses migrating over to ASP.Net MVC. Does ASP.Net MVC 3 have any advantages over Ruby On Rails for existing businesses such as possibly tying into old databases better or allowing for more complex business logic? Or is it most likely the case that they are transferring simply because they were already using ASP.Net for Winforms?

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  • Which creative framework can create these games? [closed]

    - by Rahil627
    I've used a few game frameworks in the past and have run into limitations. This lead me to "creative frameworks". I've looked into many, but I cannot determine the limitations of some of them. Selected frameworks ordered from highest to lowest level: Flash, Unity, MonoGame, OpenFrameworks (and Cinder), SFML. I want to be able to: create a game that handles drawing on an iPad create a game that uses computer vision from a webcam create a multi-device iOS game create a game that uses input from Kinect Can all of the frameworks handle this? What is the highest level framework that can handle all of them?

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  • MVC2 and MVC Futures causing RedirectToAction issues

    - by Darragh
    I've been trying to get the strongly typed version of RedirectToAction from the MVC Futures project to work, but I've been getting no where. Below are the steps I've followed, and the errors I've encountered. Any help is much appreciated. I created a new MVC2 app and changed the About action on the HomeController to redirect to the Index page. Return RedirectToAction("Index") However, I wanted to use the strongly typed extensions, so I downloaded the MVC Futures from CodePlex and added a reference to Microsoft.Web.Mvc to my project. I addded the following "import" statement to the top of HomeContoller.vb Imports Microsoft.Web.Mvc I commented out the above RedirectToAction and added the following line: Return RedirectToAction(Of HomeController)(Function(c) c.Index()) So far, so good. However, I noticed if I uncomment out the first (non Generic) RedirectToAction, it was now causing the following compile error: Error 1 Overload resolution failed because no accessible 'RedirectToAction' can be called with these arguments: Extension method 'Public Function RedirectToAction(Of TController)(action As System.Linq.Expressions.Expression(Of System.Action(Of TController))) As System.Web.Mvc.RedirectToRouteResult' defined in 'Microsoft.Web.Mvc.ControllerExtensions': Data type(s) of the type parameter(s) cannot be inferred from these arguments. Specifying the data type(s) explicitly might correct this error. Extension method 'Public Function RedirectToAction(action As System.Linq.Expressions.Expression(Of System.Action(Of HomeController))) As System.Web.Mvc.RedirectToRouteResult' defined in 'Microsoft.Web.Mvc.ControllerExtensions': Value of type 'String' cannot be converted to 'System.Linq.Expressions.Expression(Of System.Action(Of mvc2test1.HomeController))'. Even though intelli-sense was showing 8 overloads (the original 6 non-generic overloads, plus the 2 new generic overloads from the Futures assembly), it seems when trying to complie the code, the compiler would only 'find' the 2 non-gneneric extension methods from the Futures assessmbly. I thought this might be an issue that I was using conflicting versions of the MVC2 assembly, and the futures assembly, so I added MvcDiaganotics.aspx from the Futures download to my project and everytyhing looked correct: ASP.NET MVC Assembly Information (System.Web.Mvc.dll) Assembly version: ASP.NET MVC 2 RTM (2.0.50217.0) Full name: System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35 Code base: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Web.Mvc/2.0.0.0__31bf3856ad364e35/System.Web.Mvc.dll Deployment: GAC-deployed ASP.NET MVC Futures Assembly Information (Microsoft.Web.Mvc.dll) Assembly version: ASP.NET MVC 2 RTM Futures (2.0.50217.0) Full name: Microsoft.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null Code base: file:///xxxx/bin/Microsoft.Web.Mvc.DLL Deployment: bin-deployed This is driving me crazy! Becuase I thought this might be some VB issue, I created a new MVC2 project using C# and tried the same as above. I added the following "using" statement to the top of HomeController.cs using Microsoft.Web.Mvc; This time, in the About action method, I could only manage to call the non-generic RedirectToAction by typing the full commmand as follows: return Microsoft.Web.Mvc.ControllerExtensions.RedirectToAction<HomeController>(this, c => c.Index()); Even though I had a "using" statement at the top of the class, if I tried to call the non-generic RedirectToAction as follows: return RedirectToAction<HomeController>(c => c.Index()); I would get the following compile error: Error 1 The non-generic method 'System.Web.Mvc.Controller.RedirectToAction(string)' cannot be used with type arguments What gives? It's not like I'm trying to do anything out of the ordinary. It's a simple vanilla MVC2 project with only a reference to the Futures assembly. I'm hoping that I've missed out something obvious, but I've been scratching my head for too long, so I figured I'd seek some assisstance. If anyone's managed to get this simple scenario working (in VB and/or C#) could they please let me know what, if anything, they did differently? Thanks!

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  • Unit Testing in Entity Framework 4 - using CreateSourceQuery

    - by Adam
    There are many great tutorials on abstracting your EF4 context so that it can be tested against (without involving a DB). Two great (and similar) examples are here: http://blogs.msdn.com/b/adonet/archive/2009/12/17/walkthrough-test-driven-development-with-the-entity-framework-4-0.aspx (oops, not enough rep. points to post second URL) basically you wind up querying your repository using linq-to-objects while testing, and linq-to-entities while running, and usually they behave the same, but when you start hitting more advanced functionality, problems arise. Here's the question. When using linq-to-objects against IObjectSet (ie, unit testing), CreateSourceQuery returns null, which will probably cause your entire query to crash and burn. ie O = db.Orders.First(); O.OrderItems.CreateSourceQuery().ToList(); Is there a way to get CreateSourceQuery to just return the underlying collection, rather than null when working with collections? Unfortunately EntityCollection is sealed, and so cannot be mocked. This isn't really the end or the world if EF4 won't let you abstract things to this level, I just wanted to make sure there wasn't something I was missing.

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  • Mapping composite foreign keys in a many-many relationship in Entity Framework

    - by Kirk Broadhurst
    I have a Page table and a View table. There is a many-many relationship between these two via a PageView table. Unfortunately all of these tables need to have composite keys (for business reasons). Page has a primary key of (PageCode, Version), View has a primary key of (ViewCode, Version). PageView obviously enough has PageCode, ViewCode, and Version. The FK to Page is (PageCode, Version) and the FK to View is (ViewCode, Version) Makes sense and works, but when I try to map this in Entity framework I get Error 3021: Problem in mapping fragments...: Each of the following columns in table PageView is mapped to multiple conceptual side properties: PageView.Version is mapped to (PageView_Association.View.Version, PageView_Association.Page.Version) So clearly enough, EF is having a complain about the Version column being a common component of the two foreign keys. Obviously I could create a PageVersion and ViewVersion column in the join table, but that kind of defeats the point of the constraint, i.e. the Page and View must have the same Version value. Has anyone encountered this, and is there anything I can do get around it? Thanks!

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  • Entity Framework 4 and SYSUTCDATETIME ()

    - by GIbboK
    Hi, I use EF4 and C#. I have a Table in my DataBase (MS SQL 2008) with a default value for a column SYSUTCDATETIME (). The Idea is to automatically add Date and Time as soon as a new record is Created. I create my Conceptual Model using EF4, and I have created an ASP.PAGE with a DetailsView Control in INSERT MODE. My problems: When I create a new Record. EF is not able to insert the actual Date and Time value but it inserts instead this value 0001-01-01 00:00:00.00. I suppose the EF is not able to use SYSUTCDATETIME () defined in my DataBase Any idea how to solve it? Thanks Here my SQL script CREATE TABLE dbo.CmsAdvertisers ( AdvertiserId int NOT NULL IDENTITY CONSTRAINT PK_CmsAdvertisers_AdvertiserId PRIMARY KEY, DateCreated dateTime2(2) NOT NULL CONSTRAINT DF_CmsAdvertisers_DateCreated DEFAULT sysutcdatetime (), ReferenceAdvertiser varchar(64) NOT NULL, NoteInternal nvarchar(256) NOT NULL CONSTRAINT DF_CmsAdvertisers_NoteInternal DEFAULT '' ); My Temporary solution: Please guys help me on this e.Values["DateCreated"] = DateTime.UtcNow; More info here: http://msdn.microsoft.com/en-us/library/bb387157.aspx How to use the default Entity Framework and default date values http://msdn.microsoft.com/en-us/library/dd296755.aspx

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  • Entity Framework - Store parent reference on child relationship (one -> many)

    - by contactmatt
    I have a setup like this: [Table("tablename...")] public class Branch { public Branch() { Users = new List<User>(); } [Key] public int Id { get; set; } public string Name { get; set; } public List<User> Users { get; set; } } [Table("tablename...")] public class User { [Key] public int Id {get; set; } public string Username { get; set; } public string Password { get; set; } [ForeignKey("ParentBranch")] public int? ParentBranchId { get; set; } // Is this possible? public Branch ParentBranch { get; set; } // ??? } Is it possible for the User to know what parent branch it belongs to? The code above is not working. Entity Framework version 5.0 .NET 4.0 c#

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  • ASP.NET MVC Create dynamic navigation sub-menu on the master page

    - by Michael Narinsky
    I'm trying to create an ASP.NET MVC master page so the site navigation on it will look like this: Main Menu:Home | About | News Sub Menu: Home_Page1 | Home_Page2 The Sub Menu section should always show sub-menu for the currently selected Main Menu page (on the example above 'Home' page is selected) unless a user hovers the mouse on another Main Menu item (then it shows that item's sub-menu instead). What is the best way to get such functionality in ASP.NET MVC?

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  • Can we run MVC 2.0 on .Net 2.0

    - by Vinni
    Hello guys, I have an asp.net website which is already developed in .net 3.5, Now I asked to develop few pages in MVC 2.0 and few pages in DynamicData. Now Can I Run the MVC 2.0 and Dynamic Data in 3.5. When I run this i am getting lot of errors in web.config..

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  • What are good design practices when working with Entity Framework

    - by AD
    This will apply mostly for an asp.net application where the data is not accessed via soa. Meaning that you get access to the objects loaded from the framework, not Transfer Objects, although some recommendation still apply. This is a community post, so please add to it as you see fit. Applies to: Entity Framework 1.0 shipped with Visual Studio 2008 sp1. Why pick EF in the first place? Considering it is a young technology with plenty of problems (see below), it may be a hard sell to get on the EF bandwagon for your project. However, it is the technology Microsoft is pushing (at the expense of Linq2Sql, which is a subset of EF). In addition, you may not be satisfied with NHibernate or other solutions out there. Whatever the reasons, there are people out there (including me) working with EF and life is not bad.make you think. EF and inheritance The first big subject is inheritance. EF does support mapping for inherited classes that are persisted in 2 ways: table per class and table the hierarchy. The modeling is easy and there are no programming issues with that part. (The following applies to table per class model as I don't have experience with table per hierarchy, which is, anyway, limited.) The real problem comes when you are trying to run queries that include one or many objects that are part of an inheritance tree: the generated sql is incredibly awful, takes a long time to get parsed by the EF and takes a long time to execute as well. This is a real show stopper. Enough that EF should probably not be used with inheritance or as little as possible. Here is an example of how bad it was. My EF model had ~30 classes, ~10 of which were part of an inheritance tree. On running a query to get one item from the Base class, something as simple as Base.Get(id), the generated SQL was over 50,000 characters. Then when you are trying to return some Associations, it degenerates even more, going as far as throwing SQL exceptions about not being able to query more than 256 tables at once. Ok, this is bad, EF concept is to allow you to create your object structure without (or with as little as possible) consideration on the actual database implementation of your table. It completely fails at this. So, recommendations? Avoid inheritance if you can, the performance will be so much better. Use it sparingly where you have to. In my opinion, this makes EF a glorified sql-generation tool for querying, but there are still advantages to using it. And ways to implement mechanism that are similar to inheritance. Bypassing inheritance with Interfaces First thing to know with trying to get some kind of inheritance going with EF is that you cannot assign a non-EF-modeled class a base class. Don't even try it, it will get overwritten by the modeler. So what to do? You can use interfaces to enforce that classes implement some functionality. For example here is a IEntity interface that allow you to define Associations between EF entities where you don't know at design time what the type of the entity would be. public enum EntityTypes{ Unknown = -1, Dog = 0, Cat } public interface IEntity { int EntityID { get; } string Name { get; } Type EntityType { get; } } public partial class Dog : IEntity { // implement EntityID and Name which could actually be fields // from your EF model Type EntityType{ get{ return EntityTypes.Dog; } } } Using this IEntity, you can then work with undefined associations in other classes // lets take a class that you defined in your model. // that class has a mapping to the columns: PetID, PetType public partial class Person { public IEntity GetPet() { return IEntityController.Get(PetID,PetType); } } which makes use of some extension functions: public class IEntityController { static public IEntity Get(int id, EntityTypes type) { switch (type) { case EntityTypes.Dog: return Dog.Get(id); case EntityTypes.Cat: return Cat.Get(id); default: throw new Exception("Invalid EntityType"); } } } Not as neat as having plain inheritance, particularly considering you have to store the PetType in an extra database field, but considering the performance gains, I would not look back. It also cannot model one-to-many, many-to-many relationship, but with creative uses of 'Union' it could be made to work. Finally, it creates the side effet of loading data in a property/function of the object, which you need to be careful about. Using a clear naming convention like GetXYZ() helps in that regards. Compiled Queries Entity Framework performance is not as good as direct database access with ADO (obviously) or Linq2SQL. There are ways to improve it however, one of which is compiling your queries. The performance of a compiled query is similar to Linq2Sql. What is a compiled query? It is simply a query for which you tell the framework to keep the parsed tree in memory so it doesn't need to be regenerated the next time you run it. So the next run, you will save the time it takes to parse the tree. Do not discount that as it is a very costly operation that gets even worse with more complex queries. There are 2 ways to compile a query: creating an ObjectQuery with EntitySQL and using CompiledQuery.Compile() function. (Note that by using an EntityDataSource in your page, you will in fact be using ObjectQuery with EntitySQL, so that gets compiled and cached). An aside here in case you don't know what EntitySQL is. It is a string-based way of writing queries against the EF. Here is an example: "select value dog from Entities.DogSet as dog where dog.ID = @ID". The syntax is pretty similar to SQL syntax. You can also do pretty complex object manipulation, which is well explained [here][1]. Ok, so here is how to do it using ObjectQuery< string query = "select value dog " + "from Entities.DogSet as dog " + "where dog.ID = @ID"; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>(query, EntityContext.Instance)); oQuery.Parameters.Add(new ObjectParameter("ID", id)); oQuery.EnablePlanCaching = true; return oQuery.FirstOrDefault(); The first time you run this query, the framework will generate the expression tree and keep it in memory. So the next time it gets executed, you will save on that costly step. In that example EnablePlanCaching = true, which is unnecessary since that is the default option. The other way to compile a query for later use is the CompiledQuery.Compile method. This uses a delegate: static readonly Func<Entities, int, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, Dog>((ctx, id) => ctx.DogSet.FirstOrDefault(it => it.ID == id)); or using linq static readonly Func<Entities, int, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, Dog>((ctx, id) => (from dog in ctx.DogSet where dog.ID == id select dog).FirstOrDefault()); to call the query: query_GetDog.Invoke( YourContext, id ); The advantage of CompiledQuery is that the syntax of your query is checked at compile time, where as EntitySQL is not. However, there are other consideration... Includes Lets say you want to have the data for the dog owner to be returned by the query to avoid making 2 calls to the database. Easy to do, right? EntitySQL string query = "select value dog " + "from Entities.DogSet as dog " + "where dog.ID = @ID"; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>(query, EntityContext.Instance)).Include("Owner"); oQuery.Parameters.Add(new ObjectParameter("ID", id)); oQuery.EnablePlanCaching = true; return oQuery.FirstOrDefault(); CompiledQuery static readonly Func<Entities, int, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, Dog>((ctx, id) => (from dog in ctx.DogSet.Include("Owner") where dog.ID == id select dog).FirstOrDefault()); Now, what if you want to have the Include parametrized? What I mean is that you want to have a single Get() function that is called from different pages that care about different relationships for the dog. One cares about the Owner, another about his FavoriteFood, another about his FavotireToy and so on. Basicly, you want to tell the query which associations to load. It is easy to do with EntitySQL public Dog Get(int id, string include) { string query = "select value dog " + "from Entities.DogSet as dog " + "where dog.ID = @ID"; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>(query, EntityContext.Instance)) .IncludeMany(include); oQuery.Parameters.Add(new ObjectParameter("ID", id)); oQuery.EnablePlanCaching = true; return oQuery.FirstOrDefault(); } The include simply uses the passed string. Easy enough. Note that it is possible to improve on the Include(string) function (that accepts only a single path) with an IncludeMany(string) that will let you pass a string of comma-separated associations to load. Look further in the extension section for this function. If we try to do it with CompiledQuery however, we run into numerous problems: The obvious static readonly Func<Entities, int, string, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, string, Dog>((ctx, id, include) => (from dog in ctx.DogSet.Include(include) where dog.ID == id select dog).FirstOrDefault()); will choke when called with: query_GetDog.Invoke( YourContext, id, "Owner,FavoriteFood" ); Because, as mentionned above, Include() only wants to see a single path in the string and here we are giving it 2: "Owner" and "FavoriteFood" (which is not to be confused with "Owner.FavoriteFood"!). Then, let's use IncludeMany(), which is an extension function static readonly Func<Entities, int, string, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, string, Dog>((ctx, id, include) => (from dog in ctx.DogSet.IncludeMany(include) where dog.ID == id select dog).FirstOrDefault()); Wrong again, this time it is because the EF cannot parse IncludeMany because it is not part of the functions that is recognizes: it is an extension. Ok, so you want to pass an arbitrary number of paths to your function and Includes() only takes a single one. What to do? You could decide that you will never ever need more than, say 20 Includes, and pass each separated strings in a struct to CompiledQuery. But now the query looks like this: from dog in ctx.DogSet.Include(include1).Include(include2).Include(include3) .Include(include4).Include(include5).Include(include6) .[...].Include(include19).Include(include20) where dog.ID == id select dog which is awful as well. Ok, then, but wait a minute. Can't we return an ObjectQuery< with CompiledQuery? Then set the includes on that? Well, that what I would have thought so as well: static readonly Func<Entities, int, ObjectQuery<Dog>> query_GetDog = CompiledQuery.Compile<Entities, int, string, ObjectQuery<Dog>>((ctx, id) => (ObjectQuery<Dog>)(from dog in ctx.DogSet where dog.ID == id select dog)); public Dog GetDog( int id, string include ) { ObjectQuery<Dog> oQuery = query_GetDog(id); oQuery = oQuery.IncludeMany(include); return oQuery.FirstOrDefault; } That should have worked, except that when you call IncludeMany (or Include, Where, OrderBy...) you invalidate the cached compiled query because it is an entirely new one now! So, the expression tree needs to be reparsed and you get that performance hit again. So what is the solution? You simply cannot use CompiledQueries with parametrized Includes. Use EntitySQL instead. This doesn't mean that there aren't uses for CompiledQueries. It is great for localized queries that will always be called in the same context. Ideally CompiledQuery should always be used because the syntax is checked at compile time, but due to limitation, that's not possible. An example of use would be: you may want to have a page that queries which two dogs have the same favorite food, which is a bit narrow for a BusinessLayer function, so you put it in your page and know exactly what type of includes are required. Passing more than 3 parameters to a CompiledQuery Func is limited to 5 parameters, of which the last one is the return type and the first one is your Entities object from the model. So that leaves you with 3 parameters. A pitance, but it can be improved on very easily. public struct MyParams { public string param1; public int param2; public DateTime param3; } static readonly Func<Entities, MyParams, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, MyParams, IEnumerable<Dog>>((ctx, myParams) => from dog in ctx.DogSet where dog.Age == myParams.param2 && dog.Name == myParams.param1 and dog.BirthDate > myParams.param3 select dog); public List<Dog> GetSomeDogs( int age, string Name, DateTime birthDate ) { MyParams myParams = new MyParams(); myParams.param1 = name; myParams.param2 = age; myParams.param3 = birthDate; return query_GetDog(YourContext,myParams).ToList(); } Return Types (this does not apply to EntitySQL queries as they aren't compiled at the same time during execution as the CompiledQuery method) Working with Linq, you usually don't force the execution of the query until the very last moment, in case some other functions downstream wants to change the query in some way: static readonly Func<Entities, int, string, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, int, string, IEnumerable<Dog>>((ctx, age, name) => from dog in ctx.DogSet where dog.Age == age && dog.Name == name select dog); public IEnumerable<Dog> GetSomeDogs( int age, string name ) { return query_GetDog(YourContext,age,name); } public void DataBindStuff() { IEnumerable<Dog> dogs = GetSomeDogs(4,"Bud"); // but I want the dogs ordered by BirthDate gridView.DataSource = dogs.OrderBy( it => it.BirthDate ); } What is going to happen here? By still playing with the original ObjectQuery (that is the actual return type of the Linq statement, which implements IEnumerable), it will invalidate the compiled query and be force to re-parse. So, the rule of thumb is to return a List< of objects instead. static readonly Func<Entities, int, string, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, int, string, IEnumerable<Dog>>((ctx, age, name) => from dog in ctx.DogSet where dog.Age == age && dog.Name == name select dog); public List<Dog> GetSomeDogs( int age, string name ) { return query_GetDog(YourContext,age,name).ToList(); //<== change here } public void DataBindStuff() { List<Dog> dogs = GetSomeDogs(4,"Bud"); // but I want the dogs ordered by BirthDate gridView.DataSource = dogs.OrderBy( it => it.BirthDate ); } When you call ToList(), the query gets executed as per the compiled query and then, later, the OrderBy is executed against the objects in memory. It may be a little bit slower, but I'm not even sure. One sure thing is that you have no worries about mis-handling the ObjectQuery and invalidating the compiled query plan. Once again, that is not a blanket statement. ToList() is a defensive programming trick, but if you have a valid reason not to use ToList(), go ahead. There are many cases in which you would want to refine the query before executing it. Performance What is the performance impact of compiling a query? It can actually be fairly large. A rule of thumb is that compiling and caching the query for reuse takes at least double the time of simply executing it without caching. For complex queries (read inherirante), I have seen upwards to 10 seconds. So, the first time a pre-compiled query gets called, you get a performance hit. After that first hit, performance is noticeably better than the same non-pre-compiled query. Practically the same as Linq2Sql When you load a page with pre-compiled queries the first time you will get a hit. It will load in maybe 5-15 seconds (obviously more than one pre-compiled queries will end up being called), while subsequent loads will take less than 300ms. Dramatic difference, and it is up to you to decide if it is ok for your first user to take a hit or you want a script to call your pages to force a compilation of the queries. Can this query be cached? { Dog dog = from dog in YourContext.DogSet where dog.ID == id select dog; } No, ad-hoc Linq queries are not cached and you will incur the cost of generating the tree every single time you call it. Parametrized Queries Most search capabilities involve heavily parametrized queries. There are even libraries available that will let you build a parametrized query out of lamba expressions. The problem is that you cannot use pre-compiled queries with those. One way around that is to map out all the possible criteria in the query and flag which one you want to use: public struct MyParams { public string name; public bool checkName; public int age; public bool checkAge; } static readonly Func<Entities, MyParams, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, MyParams, IEnumerable<Dog>>((ctx, myParams) => from dog in ctx.DogSet where (myParams.checkAge == true && dog.Age == myParams.age) && (myParams.checkName == true && dog.Name == myParams.name ) select dog); protected List<Dog> GetSomeDogs() { MyParams myParams = new MyParams(); myParams.name = "Bud"; myParams.checkName = true; myParams.age = 0; myParams.checkAge = false; return query_GetDog(YourContext,myParams).ToList(); } The advantage here is that you get all the benifits of a pre-compiled quert. The disadvantages are that you most likely will end up with a where clause that is pretty difficult to maintain, that you will incur a bigger penalty for pre-compiling the query and that each query you run is not as efficient as it could be (particularly with joins thrown in). Another way is to build an EntitySQL query piece by piece, like we all did with SQL. protected List<Dod> GetSomeDogs( string name, int age) { string query = "select value dog from Entities.DogSet where 1 = 1 "; if( !String.IsNullOrEmpty(name) ) query = query + " and dog.Name == @Name "; if( age > 0 ) query = query + " and dog.Age == @Age "; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>( query, YourContext ); if( !String.IsNullOrEmpty(name) ) oQuery.Parameters.Add( new ObjectParameter( "Name", name ) ); if( age > 0 ) oQuery.Parameters.Add( new ObjectParameter( "Age", age ) ); return oQuery.ToList(); } Here the problems are: - there is no syntax checking during compilation - each different combination of parameters generate a different query which will need to be pre-compiled when it is first run. In this case, there are only 4 different possible queries (no params, age-only, name-only and both params), but you can see that there can be way more with a normal world search. - Noone likes to concatenate strings! Another option is to query a large subset of the data and then narrow it down in memory. This is particularly useful if you are working with a definite subset of the data, like all the dogs in a city. You know there are a lot but you also know there aren't that many... so your CityDog search page can load all the dogs for the city in memory, which is a single pre-compiled query and then refine the results protected List<Dod> GetSomeDogs( string name, int age, string city) { string query = "select value dog from Entities.DogSet where dog.Owner.Address.City == @City "; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>( query, YourContext ); oQuery.Parameters.Add( new ObjectParameter( "City", city ) ); List<Dog> dogs = oQuery.ToList(); if( !String.IsNullOrEmpty(name) ) dogs = dogs.Where( it => it.Name == name ); if( age > 0 ) dogs = dogs.Where( it => it.Age == age ); return dogs; } It is particularly useful when you start displaying all the data then allow for filtering. Problems: - Could lead to serious data transfer if you are not careful about your subset. - You can only filter on the data that you returned. It means that if you don't return the Dog.Owner association, you will not be able to filter on the Dog.Owner.Name So what is the best solution? There isn't any. You need to pick the solution that works best for you and your problem: - Use lambda-based query building when you don't care about pre-compiling your queries. - Use fully-defined pre-compiled Linq query when your object structure is not too complex. - Use EntitySQL/string concatenation when the structure could be complex and when the possible number of different resulting queries are small (which means fewer pre-compilation hits). - Use in-memory filtering when you are working with a smallish subset of the data or when you had to fetch all of the data on the data at first anyway (if the performance is fine with all the data, then filtering in memory will not cause any time to be spent in the db). Singleton access The best way to deal with your context and entities accross all your pages is to use the singleton pattern: public sealed class YourContext { private const string instanceKey = "On3GoModelKey"; YourContext(){} public static YourEntities Instance { get { HttpContext context = HttpContext.Current; if( context == null ) return Nested.instance; if (context.Items[instanceKey] == null) { On3GoEntities entity = new On3GoEntities(); context.Items[instanceKey] = entity; } return (YourEntities)context.Items[instanceKey]; } } class Nested { // Explicit static constructor to tell C# compiler // not to mark type as beforefieldinit static Nested() { } internal static readonly YourEntities instance = new YourEntities(); } } NoTracking, is it worth it? When executing a query, you can tell the framework to track the objects it will return or not. What does it mean? With tracking enabled (the default option), the framework will track what is going on with the object (has it been modified? Created? Deleted?) and will also link objects together, when further queries are made from the database, which is what is of interest here. For example, lets assume that Dog with ID == 2 has an owner which ID == 10. Dog dog = (from dog in YourContext.DogSet where dog.ID == 2 select dog).FirstOrDefault(); //dog.OwnerReference.IsLoaded == false; Person owner = (from o in YourContext.PersonSet where o.ID == 10 select dog).FirstOrDefault(); //dog.OwnerReference.IsLoaded == true; If we were to do the same with no tracking, the result would be different. ObjectQuery<Dog> oDogQuery = (ObjectQuery<Dog>) (from dog in YourContext.DogSet where dog.ID == 2 select dog); oDogQuery.MergeOption = MergeOption.NoTracking; Dog dog = oDogQuery.FirstOrDefault(); //dog.OwnerReference.IsLoaded == false; ObjectQuery<Person> oPersonQuery = (ObjectQuery<Person>) (from o in YourContext.PersonSet where o.ID == 10 select o); oPersonQuery.MergeOption = MergeOption.NoTracking; Owner owner = oPersonQuery.FirstOrDefault(); //dog.OwnerReference.IsLoaded == false; Tracking is very useful and in a perfect world without performance issue, it would always be on. But in this world, there is a price for it, in terms of performance. So, should you use NoTracking to speed things up? It depends on what you are planning to use the data for. Is there any chance that the data your query with NoTracking can be used to make update/insert/delete in the database? If so, don't use NoTracking because associations are not tracked and will causes exceptions to be thrown. In a page where there are absolutly no updates to the database, you can use NoTracking. Mixing tracking and NoTracking is possible, but it requires you to be extra careful with updates/inserts/deletes. The problem is that if you mix then you risk having the framework trying to Attach() a NoTracking object to the context where another copy of the same object exist with tracking on. Basicly, what I am saying is that Dog dog1 = (from dog in YourContext.DogSet where dog.ID == 2).FirstOrDefault(); ObjectQuery<Dog> oDogQuery = (ObjectQuery<Dog>) (from dog in YourContext.DogSet where dog.ID == 2 select dog); oDogQuery.MergeOption = MergeOption.NoTracking; Dog dog2 = oDogQuery.FirstOrDefault(); dog1 and dog2 are 2 different objects, one tracked and one not. Using the detached object in an update/insert will force an Attach() that will say "Wait a minute, I do already have an object here with the same database key. Fail". And when you Attach() one object, all of its hierarchy gets attached as well, causing problems everywhere. Be extra careful. How much faster is it with NoTracking It depends on the queries. Some are much more succeptible to tracking than other. I don't have a fast an easy rule for it, but it helps. So I should use NoTracking everywhere then? Not exactly. There are some advantages to tracking object. The first one is that the object is cached, so subsequent call for that object will not hit the database. That cache is only valid for the lifetime of the YourEntities object, which, if you use the singleton code above, is the same as the page lifetime. One page request == one YourEntity object. So for multiple calls for the same object, it will load only once per page request. (Other caching mechanism could extend that). What happens when you are using NoTracking and try to load the same object multiple times? The database will be queried each time, so there is an impact there. How often do/should you call for the same object during a single page request? As little as possible of course, but it does happens. Also remember the piece above about having the associations connected automatically for your? You don't have that with NoTracking, so if you load your data in multiple batches, you will not have a link to between them: ObjectQuery<Dog> oDogQuery = (ObjectQuery<Dog>)(from dog in YourContext.DogSet select dog); oDogQuery.MergeOption = MergeOption.NoTracking; List<Dog> dogs = oDogQuery.ToList(); ObjectQuery<Person> oPersonQuery = (ObjectQuery<Person>)(from o in YourContext.PersonSet select o); oPersonQuery.MergeOption = MergeOption.NoTracking; List<Person> owners = oPersonQuery.ToList(); In this case, no dog will have its .Owner property set. Some things to keep in mind when you are trying to optimize the performance. No lazy loading, what am I to do? This can be seen as a blessing in disguise. Of course it is annoying to load everything manually. However, it decreases the number of calls to the db and forces you to think about when you should load data. The more you can load in one database call the better. That was always true, but it is enforced now with this 'feature' of EF. Of course, you can call if( !ObjectReference.IsLoaded ) ObjectReference.Load(); if you want to, but a better practice is to force the framework to load the objects you know you will need in one shot. This is where the discussion about parametrized Includes begins to make sense. Lets say you have you Dog object public class Dog { public Dog Get(int id) { return YourContext.DogSet.FirstOrDefault(it => it.ID == id ); } } This is the type of function you work with all the time. It gets called from all over the place and once you have that Dog object, you will do very different things to it in different functions. First, it should be pre-compiled, because you will call that very often. Second, each different pages will want to have access to a different subset of the Dog data. Some will want the Owner, some the FavoriteToy, etc. Of course, you could call Load() for each reference you need anytime you need one. But that will generate a call to the database each time. Bad idea. So instead, each page will ask for the data it wants to see when it first request for the Dog object: static public Dog Get(int id) { return GetDog(entity,"");} static public Dog Get(int id, string includePath) { string query = "select value o " + " from YourEntities.DogSet as o " +

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  • SFTP with .net 3.5?

    - by nrk
    I need to connect to sftp server to download & upload file using C# in .net 3.5. Is Microsoft/.net 3.5 framework providing any inbuilt tools/mechanism/library to connect to sftp server to download & upload files?

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  • SFTP in C# with .net 3.5?

    - by nrk
    Hi, I need to connect to sftp server to download & upload file using C# in .net 3.5. Is Microsoft/.net 3.5 framework providing any inbuilt tools/mechanism/library to connect to sftp server to download & upload files? Thanks nrk

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  • Auto update the content in ASP.NET

    - by Zerotoinfinite
    I have to design a website where user can update their status, just like facebook and twitter and other social networking sites. Now my requirement is to refresh the feed with new user updates. Ex: when the new status comes facebook automatically add that on the top of the feed. on the other hand twitter shows the number of updates which is ready to be load. both ways are acceptable to me Now, I have to decide what is the best way to achieve this functionality. I am open to use ASP.NET. So I am confused that regular repeater control with timer and auto refresh or any other way? (I am wondering that if I set repeater for auto update and meanwhile if user is performing some action on any status it will lost). or do I need to change my framework from ASP.NET to ASP.NET MVC (I am little afraid with MVC as I have very less knowledge regarding it and I know it has a learning curve to master ajax/Jquery things) Any suggestion how I can I achieve it in a better and feasible way? EDIT1 I am not looking for a code but I want advice to achieve this. Supporting URL's would be appreciated. EDIT2 I am open to JQuery which can regularly check the database and fill the section. But my concern is this that if user is updating any comment and want to load/feed is automatically generated. his textbox text shouldn't be disappear (just like facebook, twitter or Linkedin) EDIT3 I have seen that on Stack overflow when any other user has modified the question/answer, I got notification like this question/answer is modified. and when I clicked on that notification only that section got reloaded. I am curious to know how to achieve this functionality. So that when user is commenting on a status/post and if meanwhile someone has updated the content then it would show the other user comment. Edit4 Could someone please recommend me an example of ASP.NET MVC 3+ which can do similar kind of activity (i.e. one input box and once user insert an text it will add the item in the list (with JQuery).

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  • Why use VB.Net instead C#?

    - by HasanGursoy
    A big company says "Minimal knowledge not to ask why don't you use C#" in its job requirements. And as a C# coder I wonder why do they prefer vb.net instead of C#. Also a Microsoft MVP uses vb.net in his Silverlight applications. Is there something Microsoft won't tell us?

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  • Why use VB.Net instead of C#?

    - by HasanGursoy
    A big company says "Minimal knowledge not to ask why don't you use C#" in its job requirements. And as a C# coder I wonder why do they prefer vb.net instead of C#. Also a Microsoft MVP uses vb.net in his Silverlight applications. Is there something Microsoft won't tell us?

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  • Binding Eval with an ImageURL in ASP.NET

    - by ramyatk06
    I'm trying to bind an image using Eval() with VB.NET and ASP.NET, but am running into issues: Code snippet <bri:ThumbViewer Id="Th1" runat="server" ImageUrl='<%# Eval("Name", "~/SiteImages/ram/3/{0}") %>' Height="100px" Width="100px" /> I set strImagePath in the code-behind as: strImagePath ="~/SiteImages/ram/3/" How can I replace: ~/SiteImages/ram/3/{0} with the variable strImagePath?

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  • What would be the best .NET 2.0 type to represent .NET 3.5 HashSet<T>?

    - by Will Marcouiller
    I'm writing myself a class library to manage Active Directory. I have an interface: Public Interface ISourceAnnuaire(Of T as {IGroupe, ITop, IUniteOrganisation, IUtilisateur}) Readonly Property Changements As Dictionary(Of T, HashSet(Of String)) End Interface This Changements property is used to save in memory the changes that occur on a particular element that is part of the source. However, I am stuck with .NET Framework 2.0. What would be the closest .NET 2.0 for HashSet(Of String)?

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  • ASP.NET MVC Project and the App_Code folder

    - by brunot
    How come App_Code is not a choices in the Add ASP.NET Folder submenu in the VS solution explorer? I realize you can create one yourself manually by just renaming a New Folder, but what is the rational here? Is this not where you are supposed to put "utility" or "service layer" type classes? On a MVC project side note. I do like the fact that there is a reference to System.Configuration out-of-the-box unlike the default ASP.NET Web Form Projects.

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