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  • ADO.NET Batch Insert with over 2000 parameters

    - by Liming
    Hello all, I'm using Enterprise library, but the idea is the same. I have a SqlStringCommand and the sql is constructed using StringBuilder in the forms of "insert into table (column1, column2, column3) values (@param1-X, @param2-X, @parm3-X)"+" " where "X" represents a "for loop" about 700 rows StringBuilder sb = new StringBuilder(); for(int i=0; i<700; i++) { sb.Append("insert into table (column1, column2, column3) values (@param1-"+i+", @param2-"+i, +",@parm3-"+i+") " ); } followed by constructing a command object injecting all the parameters w/ values into it. Essentially, 700 rows with 3 parameters, I ended up with 2100 parameters for this "one sql" Statement. It ran fine for about a few days and suddenly I got this error =============================================================== A severe error occurred on the current command. The results, if any, should be discarded. at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) at System.Data.SqlClient.SqlCommand.InternalExecuteNon Any pointers are greatly appreciated.

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  • Calling a generic function in VB.NET / C#

    - by Quandary
    Question: I want to call a generic function, defined as: Public Shared Function DeserializeFromXML(Of T)(Optional ByRef strFileNameAndPath As String = Nothing) As T Now when I call it, I wanted to do it with any of the variants below: Dim x As New XMLserialization.cConfiguration x = XMLserialization.XMLserializeLDAPconfig.DeserializeFromXML(Of x)() x = XMLserialization.XMLserializeLDAPconfig.DeserializeFromXML(GetType(x))() x = XMLserialization.XMLserializeLDAPconfig.DeserializeFromXML(Of GetType(x))() But it doesn't work. I find it very annoying and unreadable having to type x = XMLserialization.XMLserializeLDAPconfig.DeserializeFromXML(Of XMLserialization.cConfiguration)() Is there a way to call a generic function by getting the type from the instance ?

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  • Unit Testing (xUnit) an ASP.NET Mvc Controller with a custom input model?

    - by Danny Douglass
    I'm having a hard time finding information on what I expect to be a pretty straightforward scenario. I'm trying to unit test an Action on my ASP.NET Mvc 2 Controller that utilizes a custom input model w/ DataAnnotions. My testing framework is xUnit, as mentioned in the title. Here is my custom Input Model: public class EnterPasswordInputModel { [Required(ErrorMessage = "")] public string Username { get; set; } [Required(ErrorMessage = "Password is a required field.")] public string Password { get; set; } } And here is my Controller (took out some logic to simplify for this ex.): [HttpPost] public ActionResult EnterPassword(EnterPasswordInputModel enterPasswordInput) { if (!ModelState.IsValid) return View(); // do some logic to validate input // if valid - next View on successful validation return View("NextViewName"); // else - add and display error on current view return View(); } And here is my xUnit Fact (also simplified): [Fact] public void EnterPassword_WithValidInput_ReturnsNextView() { // Arrange var controller = CreateLoginController(userService.Object); // Act var result = controller.EnterPassword( new EnterPasswordInputModel { Username = username, Password = password }) as ViewResult; // Assert Assert.Equal("NextViewName", result.ViewName); } When I run my test I get the following error on my test fact when trying to retrieve the controller result (Act section): System.NullReferenceException: Object reference not set to an instance of an object. Thanks in advance for any help you can offer!

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  • Invoking code both before and after WebControl.Render method

    - by Dirk
    I have a set of custom ASP.NET server controls, most of which derive from CompositeControl. I want to implement a uniform look for "required" fields across all control types by wrapping each control in a specific piece of HTML/CSS markup. For example: <div class="requiredInputContainer"> ...custom control markup... </div> I'd love to abstract this behavior in such a way as to avoid having to do something ugly like this in every custom control, present and future: public class MyServerControl : TextBox, IRequirableField { public IRequirableField.IsRequired {get;set;} protected override void Render(HtmlTextWriter writer){ RequiredFieldHelper.RenderBeginTag(this, writer) //render custom control markup RequiredFieldHelper.RenderEndTag(this, writer) } } public static class RequiredFieldHelper{ public static void RenderBeginTag(IRequirableField field, HtmlTextWriter writer){ //check field.IsRequired, render based on its values } public static void RenderEndTag(IRequirableField field, HtmlTextWriter writer){ //check field.IsRequired , render based on its values } } If I was deriving all of my custom controls from the same base class, I could conceivably use Template Method to enforce the before/after behavior;but I have several base classes and I'd rather not end up with really a convoluted class hierarchy anyway. It feels like I should be able to design something more elegant (i.e. adheres to DRY and OCP) by leveraging the functional aspects of C#, but I'm drawing a blank.

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  • Announcing Entity Framework Code-First (CTP5 release)

    - by ScottGu
    This week the data team released the CTP5 build of the new Entity Framework Code-First library.  EF Code-First enables a pretty sweet code-centric development workflow for working with data.  It enables you to: Develop without ever having to open a designer or define an XML mapping file Define model objects by simply writing “plain old classes” with no base classes required Use a “convention over configuration” approach that enables database persistence without explicitly configuring anything Optionally override the convention-based persistence and use a fluent code API to fully customize the persistence mapping I’m a big fan of the EF Code-First approach, and wrote several blog posts about it this summer: Code-First Development with Entity Framework 4 (July 16th) EF Code-First: Custom Database Schema Mapping (July 23rd) Using EF Code-First with an Existing Database (August 3rd) Today’s new CTP5 release delivers several nice improvements over the CTP4 build, and will be the last preview build of Code First before the final release of it.  We will ship the final EF Code First release in the first quarter of next year (Q1 of 2011).  It works with all .NET application types (including both ASP.NET Web Forms and ASP.NET MVC projects). Installing EF Code First You can install and use EF Code First CTP5 using one of two ways: Approach 1) By downloading and running a setup program.  Once installed you can reference the EntityFramework.dll assembly it provides within your projects.      or: Approach 2) By using the NuGet Package Manager within Visual Studio to download and install EF Code First within a project.  To do this, simply bring up the NuGet Package Manager Console within Visual Studio (View->Other Windows->Package Manager Console) and type “Install-Package EFCodeFirst”: Typing “Install-Package EFCodeFirst” within the Package Manager Console will cause NuGet to download the EF Code First package, and add it to your current project: Doing this will automatically add a reference to the EntityFramework.dll assembly to your project:   NuGet enables you to have EF Code First setup and ready to use within seconds.  When the final release of EF Code First ships you’ll also be able to just type “Update-Package EFCodeFirst” to update your existing projects to use the final release. EF Code First Assembly and Namespace The CTP5 release of EF Code First has an updated assembly name, and new .NET namespace: Assembly Name: EntityFramework.dll Namespace: System.Data.Entity These names match what we plan to use for the final release of the library. Nice New CTP5 Improvements The new CTP5 release of EF Code First contains a bunch of nice improvements and refinements. Some of the highlights include: Better support for Existing Databases Built-in Model-Level Validation and DataAnnotation Support Fluent API Improvements Pluggable Conventions Support New Change Tracking API Improved Concurrency Conflict Resolution Raw SQL Query/Command Support The rest of this blog post contains some more details about a few of the above changes. Better Support for Existing Databases EF Code First makes it really easy to create model layers that work against existing databases.  CTP5 includes some refinements that further streamline the developer workflow for this scenario. Below are the steps to use EF Code First to create a model layer for the Northwind sample database: Step 1: Create Model Classes and a DbContext class Below is all of the code necessary to implement a simple model layer using EF Code First that goes against the Northwind database: EF Code First enables you to use “POCO” – Plain Old CLR Objects – to represent entities within a database.  This means that you do not need to derive model classes from a base class, nor implement any interfaces or data persistence attributes on them.  This enables the model classes to be kept clean, easily testable, and “persistence ignorant”.  The Product and Category classes above are examples of POCO model classes. EF Code First enables you to easily connect your POCO model classes to a database by creating a “DbContext” class that exposes public properties that map to the tables within a database.  The Northwind class above illustrates how this can be done.  It is mapping our Product and Category classes to the “Products” and “Categories” tables within the database.  The properties within the Product and Category classes in turn map to the columns within the Products and Categories tables – and each instance of a Product/Category object maps to a row within the tables. The above code is all of the code required to create our model and data access layer!  Previous CTPs of EF Code First required an additional step to work against existing databases (a call to Database.Initializer<Northwind>(null) to tell EF Code First to not create the database) – this step is no longer required with the CTP5 release.  Step 2: Configure the Database Connection String We’ve written all of the code we need to write to define our model layer.  Our last step before we use it will be to setup a connection-string that connects it with our database.  To do this we’ll add a “Northwind” connection-string to our web.config file (or App.Config for client apps) like so:   <connectionStrings>          <add name="Northwind"          connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\northwind.mdf;User Instance=true"          providerName="System.Data.SqlClient" />   </connectionStrings> EF “code first” uses a convention where DbContext classes by default look for a connection-string that has the same name as the context class.  Because our DbContext class is called “Northwind” it by default looks for a “Northwind” connection-string to use.  Above our Northwind connection-string is configured to use a local SQL Express database (stored within the \App_Data directory of our project).  You can alternatively point it at a remote SQL Server. Step 3: Using our Northwind Model Layer We can now easily query and update our database using the strongly-typed model layer we just built with EF Code First. The code example below demonstrates how to use LINQ to query for products within a specific product category.  This query returns back a sequence of strongly-typed Product objects that match the search criteria: The code example below demonstrates how we can retrieve a specific Product object, update two of its properties, and then save the changes back to the database: EF Code First handles all of the change-tracking and data persistence work for us, and allows us to focus on our application and business logic as opposed to having to worry about data access plumbing. Built-in Model Validation EF Code First allows you to use any validation approach you want when implementing business rules with your model layer.  This enables a great deal of flexibility and power. Starting with this week’s CTP5 release, EF Code First also now includes built-in support for both the DataAnnotation and IValidatorObject validation support built-into .NET 4.  This enables you to easily implement validation rules on your models, and have these rules automatically be enforced by EF Code First whenever you save your model layer.  It provides a very convenient “out of the box” way to enable validation within your applications. Applying DataAnnotations to our Northwind Model The code example below demonstrates how we could add some declarative validation rules to two of the properties of our “Product” model: We are using the [Required] and [Range] attributes above.  These validation attributes live within the System.ComponentModel.DataAnnotations namespace that is built-into .NET 4, and can be used independently of EF.  The error messages specified on them can either be explicitly defined (like above) – or retrieved from resource files (which makes localizing applications easy). Validation Enforcement on SaveChanges() EF Code-First (starting with CTP5) now automatically applies and enforces DataAnnotation rules when a model object is updated or saved.  You do not need to write any code to enforce this – this support is now enabled by default.  This new support means that the below code – which violates our above rules – will automatically throw an exception when we call the “SaveChanges()” method on our Northwind DbContext: The DbEntityValidationException that is raised when the SaveChanges() method is invoked contains a “EntityValidationErrors” property that you can use to retrieve the list of all validation errors that occurred when the model was trying to save.  This enables you to easily guide the user on how to fix them.  Note that EF Code-First will abort the entire transaction of changes if a validation rule is violated – ensuring that our database is always kept in a valid, consistent state. EF Code First’s validation enforcement works both for the built-in .NET DataAnnotation attributes (like Required, Range, RegularExpression, StringLength, etc), as well as for any custom validation rule you create by sub-classing the System.ComponentModel.DataAnnotations.ValidationAttribute base class. UI Validation Support A lot of our UI frameworks in .NET also provide support for DataAnnotation-based validation rules. For example, ASP.NET MVC, ASP.NET Dynamic Data, and Silverlight (via WCF RIA Services) all provide support for displaying client-side validation UI that honor the DataAnnotation rules applied to model objects. The screen-shot below demonstrates how using the default “Add-View” scaffold template within an ASP.NET MVC 3 application will cause appropriate validation error messages to be displayed if appropriate values are not provided: ASP.NET MVC 3 supports both client-side and server-side enforcement of these validation rules.  The error messages displayed are automatically picked up from the declarative validation attributes – eliminating the need for you to write any custom code to display them. Keeping things DRY The “DRY Principle” stands for “Do Not Repeat Yourself”, and is a best practice that recommends that you avoid duplicating logic/configuration/code in multiple places across your application, and instead specify it only once and have it apply everywhere. EF Code First CTP5 now enables you to apply declarative DataAnnotation validations on your model classes (and specify them only once) and then have the validation logic be enforced (and corresponding error messages displayed) across all applications scenarios – including within controllers, views, client-side scripts, and for any custom code that updates and manipulates model classes. This makes it much easier to build good applications with clean code, and to build applications that can rapidly iterate and evolve. Other EF Code First Improvements New to CTP5 EF Code First CTP5 includes a bunch of other improvements as well.  Below are a few short descriptions of some of them: Fluent API Improvements EF Code First allows you to override an “OnModelCreating()” method on the DbContext class to further refine/override the schema mapping rules used to map model classes to underlying database schema.  CTP5 includes some refinements to the ModelBuilder class that is passed to this method which can make defining mapping rules cleaner and more concise.  The ADO.NET Team blogged some samples of how to do this here. Pluggable Conventions Support EF Code First CTP5 provides new support that allows you to override the “default conventions” that EF Code First honors, and optionally replace them with your own set of conventions. New Change Tracking API EF Code First CTP5 exposes a new set of change tracking information that enables you to access Original, Current & Stored values, and State (e.g. Added, Unchanged, Modified, Deleted).  This support is useful in a variety of scenarios. Improved Concurrency Conflict Resolution EF Code First CTP5 provides better exception messages that allow access to the affected object instance and the ability to resolve conflicts using current, original and database values.  Raw SQL Query/Command Support EF Code First CTP5 now allows raw SQL queries and commands (including SPROCs) to be executed via the SqlQuery and SqlCommand methods exposed off of the DbContext.Database property.  The results of these method calls can be materialized into object instances that can be optionally change-tracked by the DbContext.  This is useful for a variety of advanced scenarios. Full Data Annotations Support EF Code First CTP5 now supports all standard DataAnnotations within .NET, and can use them both to perform validation as well as to automatically create the appropriate database schema when EF Code First is used in a database creation scenario.  Summary EF Code First provides an elegant and powerful way to work with data.  I really like it because it is extremely clean and supports best practices, while also enabling solutions to be implemented very, very rapidly.  The code-only approach of the library means that model layers end up being flexible and easy to customize. This week’s CTP5 release further refines EF Code First and helps ensure that it will be really sweet when it ships early next year.  I recommend using NuGet to install and give it a try today.  I think you’ll be pleasantly surprised by how awesome it is. Hope this helps, Scott

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  • Measuring ASP.NET and SharePoint output cache

    - by DigiMortal
    During ASP.NET output caching week in my local blog I wrote about how to measure ASP.NET output cache. As my posting was based on real work and real-life results then I thought that this posting is maybe interesting to you too. So here you can read what I did, how I did and what was the result. Introduction Caching is not effective without measuring it. As MVP Henn Sarv said in one of his sessions then you will get what you measure. And right he is. Lately I measured caching on local Microsoft community portal to make sure that our caching strategy is good enough in environment where this system lives. In this posting I will show you how to start measuring the cache of your web applications. Although the application measured is built on SharePoint Server publishing infrastructure, all those counters have same meaning as similar counters under pure ASP.NET applications. Measured counters I used Performance Monitor and the following performance counters (their names are similar on ASP.NET and SharePoint WCMS): Total number of objects added – how much objects were added to output cache. Total object discards – how much objects were deleted from output cache. Cache hit count – how many times requests were served by cache. Cache hit ratio – percent of requests served from cache. The first three counters are cumulative while last one is coefficient. You can use also other counters to measure the full effect of caching (memory, processor, disk I/O, network load etc before and after caching). Measuring process The measuring I describe here started from freshly restarted web server. I measured application during 12 hours that covered also time ranges when users are most active. The time range does not include late evening hours and night because there is nothing to measure during these hours. During measuring we performed no maintenance or administrative tasks on server. All tasks performed were related to usual daily content management and content monitoring. Also we had no advertisement campaigns or other promotions running at same time. The results You can see the results on following graphic.   Total number of objects added   Total object discards   Cache hit count   Cache hit ratio You can see that adds and discards are growing in same tempo. It is good because cache expires and not so popular items are not kept in memory. If there are more popular content then the these lines may have bigger distance between them. Cache hit count grows faster and this shows that more and more content is served from cache. In current case it shows that cache is filled optimally and we can do even better if we tune caches more. The site contains also pages that are discarded when some subsite changes (page was added/modified/deleted) and one modification may affect about four or five pages. This may also decrease cache hit count because during day the site gets about 5-10 new pages. Cache hit ratio is currently extremely good. The suggested minimum is about 85% but after some tuning and measuring I achieved 98.7% as a result. This is due to the fact that new pages are most often requested and after new pages are added the older ones are requested only sometimes. So they get discarded from cache and only some of these will return sometimes back to cache. Although this may also indicate the need for additional SEO work the result is very well in technical means. Conclusion Measuring ASP.NET output cache is not complex thing to do and you can start by measuring performance of cache as a start. Later you can move on and measure caching effect to other counters such as disk I/O, network, processors etc. What you have to achieve is optimal cache that is not full of items asked only couple of times per day (you can avoid this by not using too long cache durations). After some tuning you should be able to boost cache hit ratio up to at least 85%.

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  • Asp.net Session State Revisited

    - by karan@dotnet
    Every now and then I see doubts and queries which I believe is the most discussed topic in the .net environment - Asp.net Sessions. So what really are they, why are they needed and what does browser and .net do with it. These and some of the other questions I hope to answer with this post. Because of the stateless nature of the HTTP protocol there is always a need of state management in a web application. There are many other ways to store data but I feel Session state is amongst the most powerful one. The ASP.NET session state is a technology that lets you store server-side, user-specific data. Our web applications can then use data to process request from the user for which the session state was instantiated. So when does a session is first created? When we start a asp.net application a non-expiring cookie is created and its called as ASP.NET_SessionId. Basically there are two methods for this depending upon how you configure this setting in your config file. The session ID can be a part of cookie as discussed above(called as ASP.NET_SessionId) or it is embedded in the browser’s URL. For the latter part we have to set cookie-less session in our web.config file. These Session ID’s are 120-bit random number that is represented by 20-character string. The cookie will be alive until you close your browser. If you browse from one app to another within the same domain, then both the apps will use the same session ID to track the session state. Why reuse? so that you don’t have to create a new session ID for each request. One can abandon one particular Session by calling Session.Abandon() which will stop the page processing and clear out the session data. A subsequent page request causes a brand new session object to be instantiated. So what happened to my cookie? Well the session cookie is still there even when one Session.Abandon() is called and another session object is created. The Session.Abandon() lets you clear out your session state without waiting for session timeout. By default, this time-out is a 20-minute sliding expiration. This expiration is refreshed every time that the user makes a request to the Web site and presents the session ID cookie. The Abandon method sets a flag in the session state object that indicates that the session state should be abandoned. If your app does not have global.asax then your session cookie will be killed at the end of each page request. So you need to have a global.asax file and Session_Start() handler to make sure that the session cookie will remain intact once its issued after the first page hit. The runtime invokes global.asax’s Session_OnEnd() when you call Session.Abandon() or the session times out. The session manager stores session data in HttpCache with sliding expiration where this timeout can be configured in the <sessionState> of web.config file. When the timeout is up the HttpCache will remove the session state object. Sometimes we want particular pages not to time out as compared to other pages in our applications. We can handle this in two ways. First, we can set a timer or may be a JavaScript function that refreshes the page after fixed intervals of time. The only thing being the page being cached locally and then the request is not made to the server so to prevent that you can add this to your page: <%@ OutputCache Location="None" VaryByParam="None" %> Second approach is to move your page into its own folder and then add a web.config to that folder to control the timeout. Also not all pages in your application will need access to session state. For those pages that do not, you can indicate that session state is not needed and prevent session data from being fetched from the store in requests to these pages. You can disable the session state at page level like this:<%@ Page EnableSessionState="False" %>tbc…

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  • How to get full query string parameters not UrlDecoded

    - by developerit
    Introduction While developing Developer IT’s website, we came across a problem when the user search keywords containing special character like the plus ‘+’ char. We found it while looking for C++ in our search engine. The request parameter output in ASP.NET was “c “. I found it strange that it removed the ‘++’ and replaced it with a space… Analysis After a bit of Googling and Reflection, it turns out that ASP.NET calls UrlDecode on each parameters retreived by the Request(“item”) method. The Request.Params property is affected by this two since it mashes all QueryString, Forms and other collections into a single one. Workaround Finally, I solve the puzzle usign the Request.RawUrl property and parsing it with the same RegEx I use in my url re-writter. The RawUrl not affected by anything. As its name say it, it’s raw. Published on http://www.developerit.com/

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  • Parallelism in .NET – Part 5, Partitioning of Work

    - by Reed
    When parallelizing any routine, we start by decomposing the problem.  Once the problem is understood, we need to break our work into separate tasks, so each task can be run on a different processing element.  This process is called partitioning. Partitioning our tasks is a challenging feat.  There are opposing forces at work here: too many partitions adds overhead, too few partitions leaves processors idle.  Trying to work the perfect balance between the two extremes is the goal for which we should aim.  Luckily, the Task Parallel Library automatically handles much of this process.  However, there are situations where the default partitioning may not be appropriate, and knowledge of our routines may allow us to guide the framework to making better decisions. First off, I’d like to say that this is a more advanced topic.  It is perfectly acceptable to use the parallel constructs in the framework without considering the partitioning taking place.  The default behavior in the Task Parallel Library is very well-behaved, even for unusual work loads, and should rarely be adjusted.  I have found few situations where the default partitioning behavior in the TPL is not as good or better than my own hand-written partitioning routines, and recommend using the defaults unless there is a strong, measured, and profiled reason to avoid using them.  However, understanding partitioning, and how the TPL partitions your data, helps in understanding the proper usage of the TPL. I indirectly mentioned partitioning while discussing aggregation.  Typically, our systems will have a limited number of Processing Elements (PE), which is the terminology used for hardware capable of processing a stream of instructions.  For example, in a standard Intel i7 system, there are four processor cores, each of which has two potential hardware threads due to Hyperthreading.  This gives us a total of 8 PEs – theoretically, we can have up to eight operations occurring concurrently within our system. In order to fully exploit this power, we need to partition our work into Tasks.  A task is a simple set of instructions that can be run on a PE.  Ideally, we want to have at least one task per PE in the system, since fewer tasks means that some of our processing power will be sitting idle.  A naive implementation would be to just take our data, and partition it with one element in our collection being treated as one task.  When we loop through our collection in parallel, using this approach, we’d just process one item at a time, then reuse that thread to process the next, etc.  There’s a flaw in this approach, however.  It will tend to be slower than necessary, often slower than processing the data serially. The problem is that there is overhead associated with each task.  When we take a simple foreach loop body and implement it using the TPL, we add overhead.  First, we change the body from a simple statement to a delegate, which must be invoked.  In order to invoke the delegate on a separate thread, the delegate gets added to the ThreadPool’s current work queue, and the ThreadPool must pull this off the queue, assign it to a free thread, then execute it.  If our collection had one million elements, the overhead of trying to spawn one million tasks would destroy our performance. The answer, here, is to partition our collection into groups, and have each group of elements treated as a single task.  By adding a partitioning step, we can break our total work into small enough tasks to keep our processors busy, but large enough tasks to avoid overburdening the ThreadPool.  There are two clear, opposing goals here: Always try to keep each processor working, but also try to keep the individual partitions as large as possible. When using Parallel.For, the partitioning is always handled automatically.  At first, partitioning here seems simple.  A naive implementation would merely split the total element count up by the number of PEs in the system, and assign a chunk of data to each processor.  Many hand-written partitioning schemes work in this exactly manner.  This perfectly balanced, static partitioning scheme works very well if the amount of work is constant for each element.  However, this is rarely the case.  Often, the length of time required to process an element grows as we progress through the collection, especially if we’re doing numerical computations.  In this case, the first PEs will finish early, and sit idle waiting on the last chunks to finish.  Sometimes, work can decrease as we progress, since previous computations may be used to speed up later computations.  In this situation, the first chunks will be working far longer than the last chunks.  In order to balance the workload, many implementations create many small chunks, and reuse threads.  This adds overhead, but does provide better load balancing, which in turn improves performance. The Task Parallel Library handles this more elaborately.  Chunks are determined at runtime, and start small.  They grow slowly over time, getting larger and larger.  This tends to lead to a near optimum load balancing, even in odd cases such as increasing or decreasing workloads.  Parallel.ForEach is a bit more complicated, however. When working with a generic IEnumerable<T>, the number of items required for processing is not known in advance, and must be discovered at runtime.  In addition, since we don’t have direct access to each element, the scheduler must enumerate the collection to process it.  Since IEnumerable<T> is not thread safe, it must lock on elements as it enumerates, create temporary collections for each chunk to process, and schedule this out.  By default, it uses a partitioning method similar to the one described above.  We can see this directly by looking at the Visual Partitioning sample shipped by the Task Parallel Library team, and available as part of the Samples for Parallel Programming.  When we run the sample, with four cores and the default, Load Balancing partitioning scheme, we see this: The colored bands represent each processing core.  You can see that, when we started (at the top), we begin with very small bands of color.  As the routine progresses through the Parallel.ForEach, the chunks get larger and larger (seen by larger and larger stripes). Most of the time, this is fantastic behavior, and most likely will out perform any custom written partitioning.  However, if your routine is not scaling well, it may be due to a failure in the default partitioning to handle your specific case.  With prior knowledge about your work, it may be possible to partition data more meaningfully than the default Partitioner. There is the option to use an overload of Parallel.ForEach which takes a Partitioner<T> instance.  The Partitioner<T> class is an abstract class which allows for both static and dynamic partitioning.  By overriding Partitioner<T>.SupportsDynamicPartitions, you can specify whether a dynamic approach is available.  If not, your custom Partitioner<T> subclass would override GetPartitions(int), which returns a list of IEnumerator<T> instances.  These are then used by the Parallel class to split work up amongst processors.  When dynamic partitioning is available, GetDynamicPartitions() is used, which returns an IEnumerable<T> for each partition.  If you do decide to implement your own Partitioner<T>, keep in mind the goals and tradeoffs of different partitioning strategies, and design appropriately. The Samples for Parallel Programming project includes a ChunkPartitioner class in the ParallelExtensionsExtras project.  This provides example code for implementing your own, custom allocation strategies, including a static allocator of a given chunk size.  Although implementing your own Partitioner<T> is possible, as I mentioned above, this is rarely required or useful in practice.  The default behavior of the TPL is very good, often better than any hand written partitioning strategy.

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  • Parallelism in .NET – Part 12, More on Task Decomposition

    - by Reed
    Many tasks can be decomposed using a Data Decomposition approach, but often, this is not appropriate.  Frequently, decomposing the problem into distinctive tasks that must be performed is a more natural abstraction. However, as I mentioned in Part 1, Task Decomposition tends to be a bit more difficult than data decomposition, and can require a bit more effort.  Before we being parallelizing our algorithm based on the tasks being performed, we need to decompose our problem, and take special care of certain considerations such as ordering and grouping of tasks. Up to this point in this series, I’ve focused on parallelization techniques which are most appropriate when a problem space can be decomposed by data.  Using PLINQ and the Parallel class, I’ve shown how problem spaces where there is a collection of data, and each element needs to be processed, can potentially be parallelized. However, there are many other routines where this is not appropriate.  Often, instead of working on a collection of data, there is a single piece of data which must be processed using an algorithm or series of algorithms.  Here, there is no collection of data, but there may still be opportunities for parallelism. As I mentioned before, in cases like this, the approach is to look at your overall routine, and decompose your problem space based on tasks.  The idea here is to look for discrete “tasks,” individual pieces of work which can be conceptually thought of as a single operation. Let’s revisit the example I used in Part 1, an application startup path.  Say we want our program, at startup, to do a bunch of individual actions, or “tasks”.  The following is our list of duties we must perform right at startup: Display a splash screen Request a license from our license manager Check for an update to the software from our web server If an update is available, download it Setup our menu structure based on our current license Open and display our main, welcome Window Hide the splash screen The first step in Task Decomposition is breaking up the problem space into discrete tasks. This, naturally, can be abstracted as seven discrete tasks.  In the serial version of our program, if we were to diagram this, the general process would appear as: These tasks, obviously, provide some opportunities for parallelism.  Before we can parallelize this routine, we need to analyze these tasks, and find any dependencies between tasks.  In this case, our dependencies include: The splash screen must be displayed first, and as quickly as possible. We can’t download an update before we see whether one exists. Our menu structure depends on our license, so we must check for the license before setting up the menus. Since our welcome screen will notify the user of an update, we can’t show it until we’ve downloaded the update. Since our welcome screen includes menus that are customized based off the licensing, we can’t display it until we’ve received a license. We can’t hide the splash until our welcome screen is displayed. By listing our dependencies, we start to see the natural ordering that must occur for the tasks to be processed correctly. The second step in Task Decomposition is determining the dependencies between tasks, and ordering tasks based on their dependencies. Looking at these tasks, and looking at all the dependencies, we quickly see that even a simple decomposition such as this one can get quite complicated.  In order to simplify the problem of defining the dependencies, it’s often a useful practice to group our tasks into larger, discrete tasks.  The goal when grouping tasks is that you want to make each task “group” have as few dependencies as possible to other tasks or groups, and then work out the dependencies within that group.  Typically, this works best when any external dependency is based on the “last” task within the group when it’s ordered, although that is not a firm requirement.  This process is often called Grouping Tasks.  In our case, we can easily group together tasks, effectively turning this into four discrete task groups: 1. Show our splash screen – This needs to be left as its own task.  First, multiple things depend on this task, mainly because we want this to start before any other action, and start as quickly as possible. 2. Check for Update and Download the Update if it Exists - These two tasks logically group together.  We know we only download an update if the update exists, so that naturally follows.  This task has one dependency as an input, and other tasks only rely on the final task within this group. 3. Request a License, and then Setup the Menus – Here, we can group these two tasks together.  Although we mentioned that our welcome screen depends on the license returned, it also depends on setting up the menu, which is the final task here.  Setting up our menus cannot happen until after our license is requested.  By grouping these together, we further reduce our problem space. 4. Display welcome and hide splash - Finally, we can display our welcome window and hide our splash screen.  This task group depends on all three previous task groups – it cannot happen until all three of the previous groups have completed. By grouping the tasks together, we reduce our problem space, and can naturally see a pattern for how this process can be parallelized.  The diagram below shows one approach: The orange boxes show each task group, with each task represented within.  We can, now, effectively take these tasks, and run a large portion of this process in parallel, including the portions which may be the most time consuming.  We’ve now created two parallel paths which our process execution can follow, hopefully speeding up the application startup time dramatically. The main point to remember here is that, when decomposing your problem space by tasks, you need to: Define each discrete action as an individual Task Discover dependencies between your tasks Group tasks based on their dependencies Order the tasks and groups of tasks

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  • Should a c# dev switch to VB.net when the team language base is mixed?

    - by jjr2527
    I recently joined a new development team where the language preferences are mixed on the .net platform. Dev 1: Knows VB.net, does not know c# Dev 2: Knows VB.net, does not know c# Dev 3: Knows c# and VB.net, prefers c# Dev 4: Knows c# and VB6(VB.net should be pretty easy to pick up), prefers c# It seems to me that the thought leaders in the .net space are c# devs almost universally. I also thought that some 3rd party tools didn't support VB.net but when I started looking into it I didn't find any good examples. I would prefer to get the whole team on c# but if there isn't any good reason to force the issue aside from preference then I don't think that is the right choice. Are there any reasons I should lead folks away from VB.net?

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  • .NET Weak Event Handlers – Part II

    - by João Angelo
    On the first part of this article I showed two possible ways to create weak event handlers. One using reflection and the other using a delegate. For this performance analysis we will further differentiate between creating a delegate by providing the type of the listener at compile time (Explicit Delegate) vs creating the delegate with the type of the listener being only obtained at runtime (Implicit Delegate). As expected, the performance between reflection/delegate differ significantly. With the reflection based approach, creating a weak event handler is just storing a MethodInfo reference while with the delegate based approach there is the need to create the delegate which will be invoked later. So, at creating the weak event handler reflection clearly wins, but what about when the handler is invoked. No surprises there, performing a call through reflection every time a handler is invoked is costly. In conclusion, if you want good performance when creating handlers that only sporadically get triggered use reflection, otherwise use the delegate based approach. The explicit delegate approach always wins against the implicit delegate, but I find the syntax for the latter much more intuitive. // Implicit delegate - The listener type is inferred at runtime from the handler parameter public static EventHandler WrapInDelegateCall(EventHandler handler); public static EventHandler<TArgs> WrapInDelegateCall<TArgs>(EventHandler<TArgs> handler) where TArgs : EventArgs; // Explicite delegate - TListener is the type that defines the handler public static EventHandler WrapInDelegateCall<TListener>(EventHandler handler); public static EventHandler<TArgs> WrapInDelegateCall<TArgs, TListener>(EventHandler<TArgs> handler) where TArgs : EventArgs;

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  • Back From Microsoft Web Camps Beijing

    - by Dixin
    I am just back from Microsoft Web Camps, where Web developers in Beijing had a good time for 2 days with 2 fantastic speakers, Scott Hanselman and James Senior. On day 1, Scott and James talked about Web Platform Installer, ASP.NET core runtime, ASP.NET MVC, Entity Framework, Visual Studio 2010, … They were humorous and smart, and everyone was excited! On day 2, developers were organized into teams to build Web applications. At the end of day 2, each team had a chance of presentation. Before ending, I also demonstrated my so-called “WebOS”, a tiny but funny Web website developed with ASP.NET MVC and jQuery, which looks like an operating system, to show the power of ASP.NET MVC and jQuery. Scott, James and me were joking there, and people cannot help laughing and applauding… You can play with it here: http://www.coolwebos.com/, if interested. I talked with Scott and James about Web and ASP.NET, and asked some questions. I also helped on some English / Chinese translation. At the end Scott gave me a fabulous gift, which I will post to blog later. Hope Microsoft can have more and more events like this!

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  • Getting Current with Visual Studio 2010 for Web Developers

    - by plitwin
    I don't know about you, but I find it kind of crazy at times figuring out if I have the latest of everything there is for the Visual Studio 2010 developer from Microsoft. (This does not include any third-party components, just recommended updates from Microsoft.) And the be honest, the msn.microsoft.com and asp.net sites are not that helpful in figuring this out.In an effort to help, I have enumerated here what the latest VS 2010 setup should include, complete with download links. When you install everything here, you will be able to develop ASP.NET 4.0 Web Forms and ASP.NET MVC 3 applications and web sites in addition to the other stuff your version of Visual Studio supports (e.g., Silverlight, WPF, etc.). These downloads will also include NuGet and the Entity Framework 4.1, so there is no need to download this software separately.Visual Studio 2010. First of all, you need to purchase and install Visual Studio 2010 itself. For the free Express version, you can download it from Visual Web Developer 2010 ExpressVisual Studio Service Pack 1 (released Spring 2011).This is a must-have download that fixes a bunch of bugs and a number of enhancements too including preliminary support for HTML5 and CSS3. See #4 below for better support of these web technologies. Download and install from VS 2010 SP1 download page. You can find details on the features of the service pack here. ASP.NET MVC3 Tools Update (released Spring 2011)If you are using ASP.NET MVC 3, then you should also download install this update for Visual Studio from ASP.NET MVC3 Tools Update download page. This update improves Visual Studio's support for MVC 3, including better scaffolding, NuGet, Entity Framework 4.1, and more. A good overview of the updates can be found in Phil Haack's blog post.Web Standards Update for Microsoft Visual Studio 2010 SP1 (released June 2011)This is an update to VS 2010 SP1 that "brings VS 2010 intellisense & validation as close to W3C specification as we could get via means of an extension". Download and install from Web Standards Update download page. A good description of the changes can be found in the Visual Web Developer Team blog post.Note: I don't control these download pages, so it is possible they will change. If so, I will do my best to update these links. This information was current as of June 24, 2011.

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  • Visual Studio 2010 SP1

    - by ScottGu
    Last week we shipped Service Pack 1 of Visual Studio 2010 and the Visual Studio Express Tools.  In addition to bug fixes and performance improvements, SP1 includes a number of feature enhancements.  This includes improved local help support, IntelliTrace support for 64-bit applications and SharePoint, built-in Silverlight 4 Tooling support in the box, unit testing support when targeting .NET 3.5, a new performance wizard for Silverlight, IIS Express and SQL CE Tooling support for web projects, HTML5 Intellisense for ASP.NET, and more.  TFS 2010 SP1 was also released last week, together with a new TFS Project Server Integration Pack and Load Test Feature Pack.  Brian Harry has a good blog post about the TFS updates here. VS 2010 SP1 Download Click here to download and install SP1 for all versions of Visual Studio (including express).  This installer examines what you have installed on your machine, and only downloads the servicing downloads necessary to update them to SP1.  The time it takes to download and update will consequently depend on what all you have installed.  Jon Galloway has a good blog post on tips to speed up the SP1 install by uninstalling unused components. Web Platform Installer Bundles In addition to the core VS 2010 SP1 installer, we have also put together two Web Platform Installer (WebPI) bundles that automate installing SP1 together with additional web-specific components: VS 2010 SP1 WebPI Bundle Visual Web Developer 2010 SP1 WebPI Bundle The above WebPI bundles automate installing: VS 2010/VWD 2010 SP1 ASP.NET MVC 3 (runtime + tools support) IIS 7.5 Express SQL Server Compact Edition 4.0 (runtime + tools support) Web Deployment 2.0 Only the components that are not already installed on your machine will be downloaded when you use the above WebPI bundles.  This means that you can run the WebPI bundle at any time (even if you have already installed SP1 or ASP.NET MVC 3) and not have to worry about wasting time downloading/installing these components again. Earlier this year I did two posts that discussed how to use IIS Express and SQL CE with ASP.NET projects in SP1.  Read the below posts to learn more about how to use them after you run the above bundles: Visual Studio 2010 SP1 and IIS Express Visual Studio 2010 SP1 and SQL CE for ASP.NET The above feature additions work with any web project type – including both ASP.NET Web Forms and ASP.NET MVC. Additional SP1 Notes Two additional notes about VS 2010 SP1: 1) One change we made between RTM and SP1 is that by default Visual Studio now uses software rendering instead of hardware acceleration when running on Windows XP.  We made this change because we’ve seen reports of (often inconsistent) performance issues caused by older video drivers.  Running in software mode eliminates these and delivers consistent speeds.  You can optionally re-enable hardware acceleration with SP1 using Visual Studio’s Tools->Options menu command – we did not remove support for HW acceleration on XP, we simply changed the default setting for it.  Jason Zander has written more details on the change and how to re-enable HW acceleration inside VS here. 2) We have discovered an issue where installing SP1 can cause TSQL intellisense within SQL Server Management Studio 2008 R2 to stop working (typing still works – but intellisense doesn’t show up).  The SQL team is investigating this now and I’ll post an update on how to fix this once more details are known.  Hope this helps, Scott P.S. I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • .NET Properties - Use Private Set or ReadOnly Property?

    - by tgxiii
    In what situation should I use a Private Set on a property versus making it a ReadOnly property? Take into consideration the two very simplistic examples below. First example: Public Class Person Private _name As String Public Property Name As String Get Return _name End Get Private Set(ByVal value As String) _name = value End Set End Property Public Sub WorkOnName() Dim txtInfo As TextInfo = _ Threading.Thread.CurrentThread.CurrentCulture.TextInfo Me.Name = txtInfo.ToTitleCase(Me.Name) End Sub End Class // ---------- public class Person { private string _name; public string Name { get { return _name; } private set { _name = value; } } public void WorkOnName() { TextInfo txtInfo = System.Threading.Thread.CurrentThread.CurrentCulture.TextInfo; this.Name = txtInfo.ToTitleCase(this.Name); } } Second example: Public Class AnotherPerson Private _name As String Public ReadOnly Property Name As String Get Return _name End Get End Property Public Sub WorkOnName() Dim txtInfo As TextInfo = _ Threading.Thread.CurrentThread.CurrentCulture.TextInfo _name = txtInfo.ToTitleCase(_name) End Sub End Class // --------------- public class AnotherPerson { private string _name; public string Name { get { return _name; } } public void WorkOnName() { TextInfo txtInfo = System.Threading.Thread.CurrentThread.CurrentCulture.TextInfo; _name = txtInfo.ToTitleCase(_name); } } They both yield the same results. Is this a situation where there's no right and wrong, and it's just a matter of preference?

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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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  • ASP.NET with jQueryUI: text box value is getting as null in Button click event

    - by Shyju
    I have an ASP.NET page where I have a button When a user clicks on the button,I will check whether the user has logged in or not.If not logged in I will show a modal popup to login (using jQueryUI). I have placed one textbox(txtPassword) and one button(btnLogin) control in the Div which will be shown by the jQueryDialog.But in btnLogin's Click event, I am not able to read the Text value entered in the textbox txtPassword The below is my code <form id="form1" runat="server"> <div> <br /> <asp:TextBox ID="txtModelId" runat="server" Text=""></asp:TextBox><br /> <asp:Button ID="btnGo" runat="server" Text="Go" OnClick="btnGo_Click" /> <br /> <asp:Label ID="lblUserMsg" runat="server" Text="Label"></asp:Label></div> <div id="divContentHolder"> <div class="demo"> <div id="dialog" title="Login with your TradeIn Account"> <p id="validateTips">Enter your EmailId & password</p> <fieldset> <label for="email">Email</label> <asp:TextBox ID="txtEmail" CssClass="text ui-widget-content ui-corner-all" runat="server" ></asp:TextBox> <label for="password"> <asp:TextBox ID="TextBox1" runat="server" Text="sample"></asp:TextBox>Password</label> <asp:TextBox ID="txtPassword" CssClass="text ui-widget-content ui-corner-all" runat="server" ></asp:TextBox> <asp:Button ID="btnLogin" runat="server" Text="Login" OnClick="btnLogin_Click" UseSubmitBehavior="false"/> </fieldset> </div><!--dialog--> </div><!--demo--> </div><!--divContentHolder--> </form> Server side Code protected void btnGo_Click(object sender, EventArgs e) { CheckUserLoggedIn(); } private void CheckUserLoggedIn() { if (Session["username"] != null) { Response.Write("Logged in user"); ClientScript.RegisterHiddenField("isAuthenticated", "true"); } else { ClientScript.RegisterHiddenField("isAuthenticated", "false"); } } protected void btnLogin_Click(object sender, EventArgs e) { string txtSample= TextBox1.Text; // this is showing the value 'sample' string txtPass= txtPassword.Text; // this is showing null if (txtPass == "shyju") { Session["username"] = txtPassword.Text; Response.Redirect("TestingModal.aspx"); } } My java script code to render the dialog $(function() { var name = $("#name"), email = $("#email"), password = $("#password"), allFields = $([]).add(name).add(email).add(password), tips = $("#validateTips"); function updateTips(t) { tips.text(t).effect("highlight",{},1500); } function checkLength(o,n,min,max) { if ( o.val().length > max || o.val().length < min ) { o.addClass('ui-state-error'); updateTips("Length of " + n + " must be between "+min+" and "+max+"."); return false; } else { return true; } } function checkRegexp(o,regexp,n) { if ( !( regexp.test( o.val() ) ) ) { o.addClass('ui-state-error'); updateTips(n); return false; } else { return true; } } $("#dialog").dialog({ bgiframe: true, autoOpen: false, height: 300, modal: true, buttons: { 'Create an account': function() { var bValid = true; allFields.removeClass('ui-state-error'); bValid=true; if (bValid) { /*$('#users tbody').append('<tr>' + '<td>' + name.val() + '</td>' + '<td>' + email.val() + '</td>' + '<td>' + password.val() + '</td>' + '</tr>'); */ alert("Check User Credentials") $(this).dialog('close'); } }, Cancel: function() { $(this).dialog('close'); } }, close: function() { allFields.val('').removeClass('ui-state-error'); } }); $('#create-user').click(function() { $('#dialog').dialog('open'); }) .hover( function(){ $(this).addClass("ui-state-hover"); }, function(){ $(this).removeClass("ui-state-hover"); } ).mousedown(function(){ $(this).addClass("ui-state-active"); }) .mouseup(function(){ $(this).removeClass("ui-state-active"); }); var isAuthenticated = $("#isAuthenticated").val(); if (isAuthenticated && isAuthenticated == "false") { // Display the modal dialog. $("#dialog").dialog("open"); } }); I had hard coded the text properties value of TextBox1 as 'sample' in the HTML part of my ASPX file .In button click event i am getting it.But the other textbox,txtPassword 's Text property is giving me null value Please guide me to go ahead Thanks in advance

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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 0177 : 800401f3 error in classic ASP page.

    - by Arup Chaudhury
    I have some classic ASP pages showing error all of a sudden. The error is as follows: Server object error 'ASP 0177 : 800401f3' Server.CreateObject Failed /CustCare/mainwebpage_Midas.asp, line 84 Invalid ProgID. For additional information specific to this message please visit the Microsoft Online Support site located at: http://www.microsoft.com/contentredirect.asp. Now line 84 is as follows: Set MyCon = Server.CreateObject("ADODB.Connection") What can be the reason that is causing this error and how to solve it. Please suggest.

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