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  • How to generalize view?

    - by MexicanHacker
    Hey guys, I'm in the process of designing a set of views that use the same model in my app, the difference is that some views will differ in Read Only and Modifiable fields. So for example for view A I want to be able to modify A.One but no A.Two properties and for view B I want to have B.One and B.Two as modifiable fields. I was thinking in having a map that will hold this information and iterate both the modifiable and non-modifiable lists in a generic view, but I was thinking that maybe I can get feedback from you guys. What do you think?

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  • Can I Use EF Across Multiple DBs in One SQLServer Instance?

    - by thomashubschman
    Hello, I have been searching the blogs and articles but I have not found much support for this scenario. I have been poking around EF and realized that I could create views that contained data from multiple databases and then build the EF object model off of those views. Although it works I am not sure about the usual issues of performance, scalability, maintainability. The way I am achieving the connection between databases is by creating associations in the EF model. Does anyone have any information about this type of implementation? Either another solution or commentary on this proposed solution? Thanks, Tom

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  • Sometimes my dropdowns/datepickers will stop functioning?

    - by BlargINC
    Q: Where should I check to track this down? Issue: Opening a view model in my application sometimes makes dropdowns/datepickers nonfunctional. ie. dropdown won't drop and the datepicker calendar won't come up I suspect a binding issue but don't see one. Dropdowns have normal things like strings, numbers. One drop has a list of mini views. Datepickers are bound to nullable dates set in the constructor of the viewmodel. Note: These same things work in other viewmodels/views. I can paste code, I'm just not sure what code is relevant here.

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  • iPhone view architecture question

    - by Joe
    So I have (for instance) three views: A: root view B: a view functionally identical to root C: a data entry view which collects a few piece of info What I'm trying to do is reuse C to supply the data it collects to either A or B. It should supply the data to whichever of the two it is pushed onto. The data for A is similar, but functionally distinct, to what collects for B. Right now, I'm passing data from C to A or B via a singleton class. What I'm trying to avoid is having two instances of C, one to supply data to A and B (because, in actuality, the program will have 5 total views like C. Does the question make sense?

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  • iphone - navigation controller - move to first view from last view without traversing all intermedia

    - by satyam
    i'm working on iphone app which will show 4 buttons in first view. on click of a button, it will load a new view with navigation controller. this navigation controller view allows to travel upto 11 sub views. in 11th sub view, i've a reset button. on click of reset button, i've to go back to navigation controllers first view without traversing all the 11 views? is it possible to achieve it? if yes how? if no, what can be the solution?

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  • After upgrading to 2.6.35-24 kernel, why does adb no longer list devices?

    - by nbolton
    When I first installed Ubuntu 10.10 64-bit, I was able to see a physical Android device (connected via USB) in the Android Device Chooser (launched from Eclipse). But, after upgrading my kernel from 2.6.35-22-generic to 2.6.35-24-generic, no devices are listed any more, and I am unable to see any results when running adb devices like so: $ ./adb devices List of devices attached $ I have tried booting in the previous kernel version, but I get some udev error, so I was hoping I could get it working with the newer kernel version. I figured SO was the best place for this question, as it seems more developer related.

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  • problem with Expression not equal types

    - by user428547
    class first { private int? firstID; } class second { private int secondID; private int secondField; } public override Expression<Func<first, bool>> FirstFilter() { Contex db = new Contex(); List<second> list = (from p in db.second select p).ToList(); return b => list.Select(p => p.secondID).Contains(b.firstID); } and i have error: cannot convert from 'System.Collections.Generic.IEnumerable' to 'System.Collections.Generic.IEnumerable' i have tried many diferent ways, but i just don't know how can i fix it.

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  • Monotouch creating UIViews with using() blocks

    - by Socram
    When i first started using monotouch i found a page with some code samples for simple and frequent tasks... but on some of those code samples i found some things like this one: var imageRect = new RectangleF(0f, 0f, 320f, 109f); using (var myImage = new UIImageView(imageRect)) { myImage.Image = UIImage.FromFile("myImage.png"); myImage.Opaque = true; view.AddSubview(myImage); } The UIImageView is created inside a using() block. I'm a .Net developer and i know what a using() does, but i dont understand why is it used on this example. So my question is if this is the best way of creating views, and what are the differences (if any) of this aproach and creating views without the using() block.

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  • Javascript not executing (I included format.js)

    - by Brandon
    I added format.js to my controller, yet I still cannot get the js in index.js.erb to execute when I view my index page. The only thing I can figure out is that it must be because of the model name. I had to add ActiveSupport::Inflector.inflections do |inflect| inflect.irregular 'business', 'businesses' end to my inflections.rb file...because my model is called Business. my views/js are located at views/businesses/* Please help before I pull my hair out! All I have in the index.js.erb file is: alert(1); Obviously the goal is that I will get an alert when I finally get the issue fixed, letting me know it is working.

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  • How do I push a new controller via UIButton, nested in a UIScrollView?

    - by jimijon
    Hello - I have my views that are part of a tabBar. Each view has a navigationController. In one of my views I have an embeded xib component. This is a scrolling view with UIButtons inside it. I want to slide in another view, inside the navigationController when a person taps the button. I can get the taps, etc. BUT, I can't figure out how to find the controlling navigationController of that page to push the new view into. Nothing seems to work that I have tried. IS this possible? Thanks

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  • Redis suggesstion for selecting data type

    - by PHP Connect
    We have questions based where in home page we were showing 2 list Questions by date modified Question have bigger views and ans count. And in this both listing if question have same views or ans count then sorting is based on date. Previously i am directly quiring to MySQL database and fetching the values so it's easy. But each page request hitting to MySQL it's bit expensive then start doing caching. I started using Redis. Following is the cases when i use redis cache Issues is On second listing i have to display questions by votes and not answered combine. How can i stored this type of data in redis to load faster with sorting based by 2 conditions votes with time and ans count with time?

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  • How to see if type is instance of a class in Haskell?

    - by Raekye
    I'm probably doing this completely wrong (the unhaskell way); I'm just learning so please let me know if there's a better way to approach this. Context: I'm writing a bunch of tree structures. I want to reuse my prettyprint function for binary trees. Not all trees can use the generic Node/Branch data type though; different trees need different extra data. So to reuse the prettyprint function I thought of creating a class different trees would be instances of: class GenericBinaryTree a where is_leaf :: a -> Bool left :: a -> a node :: a -> b right :: a -> a This way they only have to implement methods to retrieve the left, right, and current node value, and prettyprint doesn't need to know about the internal structure. Then I get down to here: prettyprint_helper :: GenericBinaryTree a => a -> [String] prettyprint_helper tree | is_leaf tree = [] | otherwise = ("{" ++ (show (node tree)) ++ "}") : (prettyprint_subtree (left tree) (right tree)) where prettyprint_subtree left right = ((pad "+- " "| ") (prettyprint_helper right)) ++ ((pad "`- " " ") (prettyprint_helper left)) pad first rest = zipWith (++) (first : repeat rest) And I get the Ambiguous type variable 'a0' in the constraint: (Show a0) arising from a use of 'show' error for (show (node tree)) Here's an example of the most basic tree data type and instance definition (my other trees have other fields but they're irrelevant to the generic prettyprint function) data Tree a = Branch (Tree a) a (Tree a) | Leaf instance GenericBinaryTree (Tree a) where is_leaf Leaf = True is_leaf _ = False left (Branch left node right) = left right (Branch left node right) = right node (Branch left node right) = node I could have defined node :: a -> [String] and deal with the stringification in each instance/type of tree, but this feels neater. In terms of prettyprint, I only need a string representation, but if I add other generic binary tree functions later I may want the actual values. So how can I write this to work whether the node value is an instance of Show or not? Or what other way should I be approaching this problem? In an object oriented language I could easily check whether a class implements something, or if an object has a method. I can't use something like prettyprint :: Show a => a -> String Because it's not the tree that needs to be showable, it's the value inside the tree (returned by function node) that needs to be showable. I also tried changing node to Show b => a -> b without luck (and a bunch of other type class/preconditions/whatever/I don't even know what I'm doing anymore).

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  • C# Deserializing to a dictionary<string, Object>

    - by lovecraft
    I'm writing a C#/VB application to connect to a database and do stuff with the data. I was given this code to take a serialized byte array and deserialized it, which is then written to a Dictionary The line of code is: Dictionary<string, Object> DictionaryEmployee = (Dictionary<string, Object> Deserializer(byteArrayEmp)); The errors I'm getting are exceedingly unhelpful. "Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement" if I mouse over Object and "Using the generic type 'System.Collections.Generic.Dictionary' requires 2 type arguments if I mouse over Dictionary.

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  • Disk operations freeze Debian

    - by Grzenio
    Hi, I have just installed Debian testing on my new desktop and I am not very happy with performance - when I perform a disk intensive operation, e.g. upgrade packages in the system, everything seems to freeze, e.g. changing tabs in Iceweasel takes 3 seconds. I run the Debian on my 3 year old Thinkpad X60 ultra-portable, and I don't have these issues. (every single parameter of the laptop is much worse than the desktop). I am using the default packaged kernel and scripts. I run hdparm -t /dev/sda1 And I got around 96GB/s, which is expected. What else can I try to make it work better? EDIT: grzes:/home/ga# hdparm -i /dev/sda /dev/sda: Model=WDC WD15EARS-00Z5B1, FwRev=80.00A80, SerialNo=WD-WMAVU1362357 Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq } RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=50 BuffType=unknown, BuffSize=unknown, MaxMultSect=16, MultSect=16 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=2930277168 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120} PIO modes: pio0 pio3 pio4 DMA modes: mdma0 mdma1 mdma2 UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6 AdvancedPM=no WriteCache=enabled Drive conforms to: Unspecified: ATA/ATAPI-1,2,3,4,5,6,7 * signifies the current active mode EDIT2: Even my wife said "on this new computer I can't do anything when I copy the photos from the camera and its much worse than on the old one". So it must be serious. EDIT3: Updated to 2.6.32, but still no improvement EDIT4: I forgot to mention that the new disk is ext4, the old was ext3. EDIT5: Still not solved. I have a P43 ASUS P5QL-E board. Lines from dmesg that seem relevant: [ 0.370850] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 253) [ 0.370852] io scheduler noop registered [ 0.370853] io scheduler anticipatory registered [ 0.370854] io scheduler deadline registered [ 0.370876] io scheduler cfq registered (default) ... [ 0.908233] ata_piix 0000:00:1f.2: version 2.13 [ 0.908243] ata_piix 0000:00:1f.2: PCI INT B -> GSI 19 (level, low) -> IRQ 19 [ 0.908246] ata_piix 0000:00:1f.2: MAP [ P0 P2 P1 P3 ] [ 0.908275] ata_piix 0000:00:1f.2: setting latency timer to 64 [ 0.908316] scsi0 : ata_piix [ 0.908374] scsi1 : ata_piix [ 0.909180] ata1: SATA max UDMA/133 cmd 0xa000 ctl 0x9c00 bmdma 0x9480 irq 19 [ 0.909183] ata2: SATA max UDMA/133 cmd 0x9880 ctl 0x9800 bmdma 0x9488 irq 19 [ 0.909199] ata_piix 0000:00:1f.5: PCI INT B -> GSI 19 (level, low) -> IRQ 19 [ 0.909202] ata_piix 0000:00:1f.5: MAP [ P0 -- P1 -- ] [ 0.909228] ata_piix 0000:00:1f.5: setting latency timer to 64 [ 0.909279] scsi2 : ata_piix [ 0.909326] scsi3 : ata_piix [ 0.910021] ata3: SATA max UDMA/133 cmd 0xb000 ctl 0xac00 bmdma 0xa480 irq 19 [ 0.910024] ata4: SATA max UDMA/133 cmd 0xa880 ctl 0xa800 bmdma 0xa488 irq 19 [ 0.915575] FDC 0 is a post-1991 82077 ... [ 1.716062] ata1.00: SATA link up 3.0 Gbps (SStatus 123 SControl 300) [ 1.716074] ata1.01: SATA link down (SStatus 0 SControl 300) [ 1.724318] ata1.00: ATA-8: WDC WD15EARS-00Z5B1, 80.00A80, max UDMA/133 [ 1.724322] ata1.00: 2930277168 sectors, multi 16: LBA48 NCQ (depth 0/32) [ 1.740339] ata1.00: configured for UDMA/133 [ 1.740428] scsi 0:0:0:0: Direct-Access ATA WDC WD15EARS-00Z 80.0 PQ: 0 ANSI: 5 [ 1.746788] scsi 6:0:0:0: CD-ROM ASUS DRW-1608P 1.17 PQ: 0 ANSI: 5 ... [ 1.925981] sd 0:0:0:0: [sda] 2930277168 512-byte logical blocks: (1.50 TB/1.36 TiB) [ 1.926005] sd 0:0:0:0: [sda] Write Protect is off [ 1.926007] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 [ 1.926020] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 1.926092] sda:sr0: scsi3-mmc drive: 40x/40x writer cd/rw xa/form2 cdda tray [ 1.931106] Uniform CD-ROM driver Revision: 3.20 [ 1.931191] sr 6:0:0:0: Attached scsi CD-ROM sr0 ... [ 1.941936] sda1 sda2 sda3 sda4 < sda5 sda6 > [ 1.967691] sd 0:0:0:0: [sda] Attached SCSI disk [ 1.970938] sd 0:0:0:0: Attached scsi generic sg0 type 0 [ 1.970959] sr 6:0:0:0: Attached scsi generic sg1 type 5 ... [ 2.500086] EXT4-fs (sda3): mounted filesystem with ordered data mode ... [ 7.150468] EXT4-fs (sda6): mounted filesystem with ordered data mode

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  • why nginx rewrite post request from /login to //login?

    - by jiangchengwu
    There is a if statement, which will rewrite url when the client is Android. Everything ok. But, something got strange. Nginx will write post request /login to //login, even if the block of if statement is bank. So I got a 404 page. As the jetty server only accept /login request. Server conf: location / { proxy_pass http://localhost:8785/; proxy_set_header Host $http_host; proxy_set_header Remote-Addr $http_remote_addr; proxy_set_header X-Real-IP $remote_addr; if ( $http_user_agent ~ Android ){ # rewrite something, been commented } } Debug info, origin log https://gist.github.com/3799021 ... 2012/09/28 16:29:49 [debug] 26416#0: *1 http script regex: "Android" 2012/09/28 16:29:49 [notice] 26416#0: *1 "Android" matches "Android/1.0", client: 106.187.97.22, server: ireedr.com, request: "POST /login HTTP/1.1", host: "ireedr.com" ... 2012/09/28 16:29:49 [debug] 26416#0: *1 http proxy header: "POST //login HTTP/1.0 Host: ireedr.com X-Real-IP: 106.187.97.22 Connection: close Accept-Encoding: identity, deflate, compress, gzip Accept: */* User-Agent: Android/1.0 " ... 2012/09/28 16:29:49 [debug] 26416#0: *1 HTTP/1.1 404 Not Found Server: nginx/1.2.1 Date: Fri, 28 Sep 2012 08:29:49 GMT Content-Type: text/html;charset=ISO-8859-1 Transfer-Encoding: chunked Connection: keep-alive Cache-Control: must-revalidate,no-cache,no-store Content-Encoding: gzip ... Only when I commented the block in the configration file: location / { proxy_pass http://localhost:8785/; proxy_set_header Host $http_host; proxy_set_header Remote-Addr $http_remote_addr; proxy_set_header X-Real-IP $remote_addr; #if ( $http_user_agent ~ Android ){ # #} } The client can get an 200 response. Debug info, origin log https://gist.github.com/3799023 ... "POST /login HTTP/1.0 Host: ireedr.com X-Real-IP: 106.187.97.22 Connection: close Accept-Encoding: identity, deflate, compress, gzip Accept: */* User-Agent: Android/1.0 " ... 2012/09/28 16:27:19 [debug] 26319#0: *1 HTTP/1.1 200 OK Server: nginx/1.2.1 Date: Fri, 28 Sep 2012 08:27:19 GMT Content-Type: application/json;charset=UTF-8 Content-Length: 17 Connection: keep-alive ... As the log: 2012/09/28 16:29:49 [notice] 26416#0: *1 "Android" matches "Android/1.0", client: 106.187.97.22, server: ireedr.com, request: "POST /login HTTP/1.1", host: "ireedr.com" 2012/09/28 16:29:49 [debug] 26416#0: *1 http script if 2012/09/28 16:29:49 [debug] 26416#0: *1 post rewrite phase: 4 2012/09/28 16:29:49 [debug] 26416#0: *1 generic phase: 5 2012/09/28 16:29:49 [debug] 26416#0: *1 generic phase: 6 2012/09/28 16:29:49 [debug] 26416#0: *1 generic phase: 7 2012/09/28 16:29:49 [debug] 26416#0: *1 access phase: 8 2012/09/28 16:29:49 [debug] 26416#0: *1 access phase: 9 2012/09/28 16:29:49 [debug] 26416#0: *1 access phase: 10 2012/09/28 16:29:49 [debug] 26416#0: *1 post access phase: 11 2012/09/28 16:29:49 [debug] 26416#0: *1 try files phase: 12 2012/09/28 16:29:49 [debug] 26416#0: *1 posix_memalign: 0000000001E798F0:4096 @16 2012/09/28 16:29:49 [debug] 26416#0: *1 http init upstream, client timer: 0 2012/09/28 16:29:49 [debug] 26416#0: *1 epoll add event: fd:13 op:3 ev:80000005 2012/09/28 16:29:49 [debug] 26416#0: *1 http script copy: "Host: " 2012/09/28 16:29:49 [debug] 26416#0: *1 http script var: "ireedr.com" 2012/09/28 16:29:49 [debug] 26416#0: *1 http script copy: " " 2012/09/28 16:29:49 [debug] 26416#0: *1 http script copy: "" 2012/09/28 16:29:49 [debug] 26416#0: *1 http script copy: "" 2012/09/28 16:29:49 [debug] 26416#0: *1 http script copy: "X-Real-IP: " 2012/09/28 16:29:49 [debug] 26416#0: *1 http script var: "106.187.97.22" 2012/09/28 16:29:49 [debug] 26416#0: *1 http script copy: " " 2012/09/28 16:29:49 [debug] 26416#0: *1 http script copy: "Connection: close " 2012/09/28 16:29:49 [debug] 26416#0: *1 http proxy header: "Accept-Encoding: identity, deflate, compress, gzip" 2012/09/28 16:29:49 [debug] 26416#0: *1 http proxy header: "Accept: */*" 2012/09/28 16:29:49 [debug] 26416#0: *1 http proxy header: "User-Agent: Android/1.0" 2012/09/28 16:29:49 [debug] 26416#0: *1 http proxy header: "POST //login HTTP/1.0 Host: ireedr.com X-Real-IP: 106.187.97.22 Connection: close Accept-Encoding: identity, deflate, compress, gzip Accept: */* User-Agent: Android/1.0 " ... Maybe post rewrite phase had rewrite the request. Anybody can help me to solve this problem or know why nginx do that ? Much appreciated.

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  • ASP.NET MVC 3 Hosting :: New Features in ASP.NET MVC 3

    - by mbridge
    Razor View Engine The Razor view engine is a new view engine option for ASP.NET MVC that supports the Razor templating syntax. The Razor syntax is a streamlined approach to HTML templating designed with the goal of being a code driven minimalist templating approach that builds on existing C#, VB.NET and HTML knowledge. The result of this approach is that Razor views are very lean and do not contain unnecessary constructs that get in the way of you and your code. ASP.NET MVC 3 Preview 1 only supports C# Razor views which use the .cshtml file extension. VB.NET support will be enabled in later releases of ASP.NET MVC 3. For more information and examples, see Introducing “Razor” – a new view engine for ASP.NET on Scott Guthrie’s blog. Dynamic View and ViewModel Properties A new dynamic View property is available in views, which provides access to the ViewData object using a simpler syntax. For example, imagine two items are added to the ViewData dictionary in the Index controller action using code like the following: public ActionResult Index() {          ViewData["Title"] = "The Title";          ViewData["Message"] = "Hello World!"; } Those properties can be accessed in the Index view using code like this: <h2>View.Title</h2> <p>View.Message</p> There is also a new dynamic ViewModel property in the Controller class that lets you add items to the ViewData dictionary using a simpler syntax. Using the previous controller example, the two values added to the ViewData dictionary can be rewritten using the following code: public ActionResult Index() {     ViewModel.Title = "The Title";     ViewModel.Message = "Hello World!"; } “Add View” Dialog Box Supports Multiple View Engines The Add View dialog box in Visual Studio includes extensibility hooks that allow it to support multiple view engines, as shown in the following figure: Service Location and Dependency Injection Support ASP.NET MVC 3 introduces improved support for applying Dependency Injection (DI) via Inversion of Control (IoC) containers. ASP.NET MVC 3 Preview 1 provides the following hooks for locating services and injecting dependencies: - Creating controller factories. - Creating controllers and setting dependencies. - Setting dependencies on view pages for both the Web Form view engine and the Razor view engine (for types that derive from ViewPage, ViewUserControl, ViewMasterPage, WebViewPage). - Setting dependencies on action filters. Using a Dependency Injection container is not required in order for ASP.NET MVC 3 to function properly. Global Filters ASP.NET MVC 3 allows you to register filters that apply globally to all controller action methods. Adding a filter to the global filters collection ensures that the filter runs for all controller requests. To register an action filter globally, you can make the following call in the Application_Start method in the Global.asax file: GlobalFilters.Filters.Add(new MyActionFilter()); The source of global action filters is abstracted by the new IFilterProvider interface, which can be registered manually or by using Dependency Injection. This allows you to provide your own source of action filters and choose at run time whether to apply a filter to an action in a particular request. New JsonValueProviderFactory Class The new JsonValueProviderFactory class allows action methods to receive JSON-encoded data and model-bind it to an action-method parameter. This is useful in scenarios such as client templating. Client templates enable you to format and display a single data item or set of data items by using a fragment of HTML. ASP.NET MVC 3 lets you connect client templates easily with an action method that both returns and receives JSON data. Support for .NET Framework 4 Validation Attributes and IvalidatableObject The ValidationAttribute class was improved in the .NET Framework 4 to enable richer support for validation. When you write a custom validation attribute, you can use a new IsValid overload that provides a ValidationContext instance. This instance provides information about the current validation context, such as what object is being validated. This change enables scenarios such as validating the current value based on another property of the model. The following example shows a sample custom attribute that ensures that the value of PropertyOne is always larger than the value of PropertyTwo: public class CompareValidationAttribute : ValidationAttribute {     protected override ValidationResult IsValid(object value,              ValidationContext validationContext) {         var model = validationContext.ObjectInstance as SomeModel;         if (model.PropertyOne > model.PropertyTwo) {            return ValidationResult.Success;         }         return new ValidationResult("PropertyOne must be larger than PropertyTwo");     } } Validation in ASP.NET MVC also supports the .NET Framework 4 IValidatableObject interface. This interface allows your model to perform model-level validation, as in the following example: public class SomeModel : IValidatableObject {     public int PropertyOne { get; set; }     public int PropertyTwo { get; set; }     public IEnumerable<ValidationResult> Validate(ValidationContext validationContext) {         if (PropertyOne <= PropertyTwo) {            yield return new ValidationResult(                "PropertyOne must be larger than PropertyTwo");         }     } } New IClientValidatable Interface The new IClientValidatable interface allows the validation framework to discover at run time whether a validator has support for client validation. This interface is designed to be independent of the underlying implementation; therefore, where you implement the interface depends on the validation framework in use. For example, for the default data annotations-based validator, the interface would be applied on the validation attribute. Support for .NET Framework 4 Metadata Attributes ASP.NET MVC 3 now supports .NET Framework 4 metadata attributes such as DisplayAttribute. New IMetadataAware Interface The new IMetadataAware interface allows you to write attributes that simplify how you can contribute to the ModelMetadata creation process. Before this interface was available, you needed to write a custom metadata provider in order to have an attribute provide extra metadata. This interface is consumed by the AssociatedMetadataProvider class, so support for the IMetadataAware interface is automatically inherited by all classes that derive from that class (notably, the DataAnnotationsModelMetadataProvider class). New Action Result Types In ASP.NET MVC 3, the Controller class includes two new action result types and corresponding helper methods. HttpNotFoundResult Action The new HttpNotFoundResult action result is used to indicate that a resource requested by the current URL was not found. The status code is 404. This class derives from HttpStatusCodeResult. The Controller class includes an HttpNotFound method that returns an instance of this action result type, as shown in the following example: public ActionResult List(int id) {     if (id < 0) {                 return HttpNotFound();     }     return View(); } HttpStatusCodeResult Action The new HttpStatusCodeResult action result is used to set the response status code and description. Permanent Redirect The HttpRedirectResult class has a new Boolean Permanent property that is used to indicate whether a permanent redirect should occur. A permanent redirect uses the HTTP 301 status code. Corresponding to this change, the Controller class now has several methods for performing permanent redirects: - RedirectPermanent - RedirectToRoutePermanent - RedirectToActionPermanent These methods return an instance of HttpRedirectResult with the Permanent property set to true. Breaking Changes The order of execution for exception filters has changed for exception filters that have the same Order value. In ASP.NET MVC 2 and earlier, exception filters on the controller with the same Order as those on an action method were executed before the exception filters on the action method. This would typically be the case when exception filters were applied without a specified order Order value. In MVC 3, this order has been reversed in order to allow the most specific exception handler to execute first. As in earlier versions, if the Order property is explicitly specified, the filters are run in the specified order. Known Issues When you are editing a Razor view (CSHTML file), the Go To Controller menu item in Visual Studio will not be available, and there are no code snippets.

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  • Error on 64 Bit Install of IIS &ndash; LoadLibraryEx failed on aspnet_filter.dll

    - by Rick Strahl
    I’ve been having a few problems with my Windows 7 install and trying to get IIS applications to run properly in 64 bit. After installing IIS and creating virtual directories for several of my applications and firing them up I was left with the following error message from IIS: Calling LoadLibraryEx on ISAPI filter “c:\windows\Microsoft.NET\Framework\v4.0.30319\aspnet_filter.dll” failed This is on Windows 7 64 bit and running on an ASP.NET 4.0 Application configured for running 64 bit (32 bit disabled). It’s also on what is essentially a brand new installation of IIS and Windows 7. So it failed right out of the box. The problem here is that IIS is trying to loading this ISAPI filter from the 32 bit folder – it should be loading from Framework64 folder note the Framework folder. The aspnet_filter.dll component is a small Win32 ISAPI filter used to back up the cookieless session state for ASP.NET on IIS 7 applications. It’s not terribly important because of this focus, but it’s a default loaded component. After a lot of fiddling I ended up with two solutions (with the help and support of some Twitter folks): Switch IIS to run in 32 bit mode Fix the filter listing in ApplicationHost.config Switching IIS to allow 32 Bit Code This is a quick fix for the problem above which enables 32 bit code in the Application Pool. The problem above is that IIS is trying to load a 32 bit ISAPI filter and enabling 32 bit code gets you around this problem. To configure your Application Pool, open the Application Pool in IIS Manager bring up Advanced Options and Enable 32 Bit Applications: And voila the error message above goes away. Fix Filters Enabling 32 bit code is a quick fix solution to this problem, but not an ideal one. If you’re running a pure .NET application that doesn’t need to do COM or pInvoke Interop with 32 bit apps there’s usually no need for enabling 32 bit code in an Application Pool as you can run in native 64 bit code. So trying to get 64 bit working natively is a pretty key feature in my opinion :-) So what’s the problem – why is IIS trying to load a 32 bit DLL in a 64 bit install, especially if the application pool is configured to not allow 32 bit code at all? The problem lies in the server configuration and the fact that 32 bit and 64 bit configuration settings exist side by side in IIS. If I open my Default Web Site (or any other root Web Site) and go to the ISAPI filter list here’s what I see: Notice that there are 3 entries for ASP.NET 4.0 in this list. Only two of them however are specifically scoped to the specifically to 32 bit or 64 bit. As you can see the 64 bit filter correctly points at the Framework64 folder to load the dll, while both the 32 bit and the ‘generic’ entry point at the plain Framework 32 bit folder. Aha! Hence lies our problem. You can edit ApplicationHost.config manually, but I ran into the nasty issue of not being able to easily edit that file with the 32 bit editor (who ever thought that was a good idea???? WTF). You have to open ApplicationHost.Config in a 64 bit native text editor – which Visual Studio is not. Or my favorite editor: EditPad Pro. Since I don’t have a native 64 bit editor handy Notepad was my only choice. Or as an alternative you can use the IIS 7.5 Configuration Editor which lets you interactively browse and edit most ApplicationHost settings. You can drill into the configuration hierarchy visually to find your keys and edit attributes and sub values in property editor type interface. I had no idea this tool existed prior to today and it’s pretty cool as it gives you some visual clues to options available – especially in absence of an Intellisense scheme you’d get in Visual Studio (which doesn’t work). To use the Configuration Editor go the Web Site root and use the Configuration Editor option in the Management Group. Drill into System.webServer/isapiFilters and then click on the Collection’s … button on the right. You should now see a display like this: which shows all the same attributes you’d see in ApplicationHost.config (cool!). These entries correspond to these raw ApplicationHost.config entries: <filter name="ASP.Net_4.0" path="C:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_filter.dll" enableCache="true" preCondition="runtimeVersionv4.0" /> <filter name="ASP.Net_4.0_64bit" path="C:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet_filter.dll" enableCache="true" preCondition="runtimeVersionv4.0,bitness64" /> <filter name="ASP.Net_4.0_32bit" path="C:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_filter.dll" enableCache="true" preCondition="runtimeVersionv4.0,bitness32" /> The key attribute we’re concerned with here is the preCondition and the bitness subvalue. Notice that the ‘generic’ version – which comes first in the filter list – has no bitness assigned to it, so it defaults to 32 bit and the 32 bit dll path. And this is where our problem comes from. The simple solution to fix the startup problem is to remove the generic entry from this list here or in the filters list shown earlier and leave only the bitness specific versions active. The preCondition attribute acts as a filter and as you can see here it filters the list by runtime version and bitness value. This is something to keep an eye out in general – if a bitness values are missing it’s easy to run into conflicts like this with any settings that are global and especially those that load modules and handlers and other executable code. On 64 bit systems it’s a good idea to explicitly set the bitness of all entries or remove the non-specific versions and add bit specific entries. So how did this get misconfigured? I installed IIS before everything else was installed on this machine and then went ahead and installed Visual Studio. I suspect the Visual Studio install munged this up as I never saw a similar problem on my live server where everything just worked right out of the box. In searching about this problem a lot of solutions pointed at using aspnet_regiis –r from the Framework64 directory, but that did not fix this extra entry in the filters list – it adds the required 32 bit and 64 bit entries, but it doesn’t remove the errand un-bitness set entry. Hopefully this post will help out anybody who runs into a similar situation without having to trouble shoot all the way down into the configuration settings and noticing the bitness settings. It’s a good lesson learned for me – this is my first desktop install of a 64 bit OS and things like this are what I was reluctant to find. Now that I ran into this I have a good idea what to look for with 32/64 bit misconfigurations in IIS at least.© Rick Strahl, West Wind Technologies, 2005-2011Posted in IIS7   ASP.NET  

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  • Announcing release of ASP.NET MVC 3, IIS Express, SQL CE 4, Web Farm Framework, Orchard, WebMatrix

    - by ScottGu
    I’m excited to announce the release today of several products: ASP.NET MVC 3 NuGet IIS Express 7.5 SQL Server Compact Edition 4 Web Deploy and Web Farm Framework 2.0 Orchard 1.0 WebMatrix 1.0 The above products are all free. They build upon the .NET 4 and VS 2010 release, and add a ton of additional value to ASP.NET (both Web Forms and MVC) and the Microsoft Web Server stack. ASP.NET MVC 3 Today we are shipping the final release of ASP.NET MVC 3.  You can download and install ASP.NET MVC 3 here.  The ASP.NET MVC 3 source code (released under an OSI-compliant open source license) can also optionally be downloaded here. ASP.NET MVC 3 is a significant update that brings with it a bunch of great features.  Some of the improvements include: Razor ASP.NET MVC 3 ships with a new view-engine option called “Razor” (in addition to continuing to support/enhance the existing .aspx view engine).  Razor minimizes the number of characters and keystrokes required when writing a view template, and enables a fast, fluid coding workflow. Unlike most template syntaxes, with Razor you do not need to interrupt your coding to explicitly denote the start and end of server blocks within your HTML. The Razor parser is smart enough to infer this from your code. This enables a compact and expressive syntax which is clean, fast and fun to type.  You can learn more about Razor from some of the blog posts I’ve done about it over the last 6 months Introducing Razor New @model keyword in Razor Layouts with Razor Server-Side Comments with Razor Razor’s @: and <text> syntax Implicit and Explicit code nuggets with Razor Layouts and Sections with Razor Today’s release supports full code intellisense support for Razor (both VB and C#) with Visual Studio 2010 and the free Visual Web Developer 2010 Express. JavaScript Improvements ASP.NET MVC 3 enables richer JavaScript scenarios and takes advantage of emerging HTML5 capabilities. The AJAX and Validation helpers in ASP.NET MVC 3 now use an Unobtrusive JavaScript based approach.  Unobtrusive JavaScript avoids injecting inline JavaScript into HTML, and enables cleaner separation of behavior using the new HTML 5 “data-“ attribute convention (which conveniently works on older browsers as well – including IE6). This keeps your HTML tight and clean, and makes it easier to optionally swap out or customize JS libraries.  ASP.NET MVC 3 now includes built-in support for posting JSON-based parameters from client-side JavaScript to action methods on the server.  This makes it easier to exchange data across the client and server, and build rich JavaScript front-ends.  We think this capability will be particularly useful going forward with scenarios involving client templates and data binding (including the jQuery plugins the ASP.NET team recently contributed to the jQuery project).  Previous releases of ASP.NET MVC included the core jQuery library.  ASP.NET MVC 3 also now ships the jQuery Validate plugin (which our validation helpers use for client-side validation scenarios).  We are also now shipping and including jQuery UI by default as well (which provides a rich set of client-side JavaScript UI widgets for you to use within projects). Improved Validation ASP.NET MVC 3 includes a bunch of validation enhancements that make it even easier to work with data. Client-side validation is now enabled by default with ASP.NET MVC 3 (using an onbtrusive javascript implementation).  Today’s release also includes built-in support for Remote Validation - which enables you to annotate a model class with a validation attribute that causes ASP.NET MVC to perform a remote validation call to a server method when validating input on the client. The validation features introduced within .NET 4’s System.ComponentModel.DataAnnotations namespace are now supported by ASP.NET MVC 3.  This includes support for the new IValidatableObject interface – which enables you to perform model-level validation, and allows you to provide validation error messages specific to the state of the overall model, or between two properties within the model.  ASP.NET MVC 3 also supports the improvements made to the ValidationAttribute class in .NET 4.  ValidationAttribute now supports a new IsValid overload that provides more information about the current validation context, such as what object is being validated.  This enables richer scenarios where you can validate the current value based on another property of the model.  We’ve shipped a built-in [Compare] validation attribute  with ASP.NET MVC 3 that uses this support and makes it easy out of the box to compare and validate two property values. You can use any data access API or technology with ASP.NET MVC.  This past year, though, we’ve worked closely with the .NET data team to ensure that the new EF Code First library works really well for ASP.NET MVC applications.  These two posts of mine cover the latest EF Code First preview and demonstrates how to use it with ASP.NET MVC 3 to enable easy editing of data (with end to end client+server validation support).  The final release of EF Code First will ship in the next few weeks. Today we are also publishing the first preview of a new MvcScaffolding project.  It enables you to easily scaffold ASP.NET MVC 3 Controllers and Views, and works great with EF Code-First (and is pluggable to support other data providers).  You can learn more about it – and install it via NuGet today - from Steve Sanderson’s MvcScaffolding blog post. Output Caching Previous releases of ASP.NET MVC supported output caching content at a URL or action-method level. With ASP.NET MVC V3 we are also enabling support for partial page output caching – which allows you to easily output cache regions or fragments of a response as opposed to the entire thing.  This ends up being super useful in a lot of scenarios, and enables you to dramatically reduce the work your application does on the server.  The new partial page output caching support in ASP.NET MVC 3 enables you to easily re-use cached sub-regions/fragments of a page across multiple URLs on a site.  It supports the ability to cache the content either on the web-server, or optionally cache it within a distributed cache server like Windows Server AppFabric or memcached. I’ll post some tutorials on my blog that show how to take advantage of ASP.NET MVC 3’s new output caching support for partial page scenarios in the future. Better Dependency Injection ASP.NET MVC 3 provides better support for applying Dependency Injection (DI) and integrating with Dependency Injection/IOC containers. With ASP.NET MVC 3 you no longer need to author custom ControllerFactory classes in order to enable DI with Controllers.  You can instead just register a Dependency Injection framework with ASP.NET MVC 3 and it will resolve dependencies not only for Controllers, but also for Views, Action Filters, Model Binders, Value Providers, Validation Providers, and Model Metadata Providers that you use within your application. This makes it much easier to cleanly integrate dependency injection within your projects. Other Goodies ASP.NET MVC 3 includes dozens of other nice improvements that help to both reduce the amount of code you write, and make the code you do write cleaner.  Here are just a few examples: Improved New Project dialog that makes it easy to start new ASP.NET MVC 3 projects from templates. Improved Add->View Scaffolding support that enables the generation of even cleaner view templates. New ViewBag property that uses .NET 4’s dynamic support to make it easy to pass late-bound data from Controllers to Views. Global Filters support that allows specifying cross-cutting filter attributes (like [HandleError]) across all Controllers within an app. New [AllowHtml] attribute that allows for more granular request validation when binding form posted data to models. Sessionless controller support that allows fine grained control over whether SessionState is enabled on a Controller. New ActionResult types like HttpNotFoundResult and RedirectPermanent for common HTTP scenarios. New Html.Raw() helper to indicate that output should not be HTML encoded. New Crypto helpers for salting and hashing passwords. And much, much more… Learn More about ASP.NET MVC 3 We will be posting lots of tutorials and samples on the http://asp.net/mvc site in the weeks ahead.  Below are two good ASP.NET MVC 3 tutorials available on the site today: Build your First ASP.NET MVC 3 Application: VB and C# Building the ASP.NET MVC 3 Music Store We’ll post additional ASP.NET MVC 3 tutorials and videos on the http://asp.net/mvc site in the future. Visit it regularly to find new tutorials as they are published. How to Upgrade Existing Projects ASP.NET MVC 3 is compatible with ASP.NET MVC 2 – which means it should be easy to update existing MVC projects to ASP.NET MVC 3.  The new features in ASP.NET MVC 3 build on top of the foundational work we’ve already done with the MVC 1 and MVC 2 releases – which means that the skills, knowledge, libraries, and books you’ve acquired are all directly applicable with the MVC 3 release.  MVC 3 adds new features and capabilities – it doesn’t obsolete existing ones. You can upgrade existing ASP.NET MVC 2 projects by following the manual upgrade steps in the release notes.  Alternatively, you can use this automated ASP.NET MVC 3 upgrade tool to easily update your  existing projects. Localized Builds Today’s ASP.NET MVC 3 release is available in English.  We will be releasing localized versions of ASP.NET MVC 3 (in 9 languages) in a few days.  I’ll blog pointers to the localized downloads once they are available. NuGet Today we are also shipping NuGet – a free, open source, package manager that makes it easy for you to find, install, and use open source libraries in your projects. It works with all .NET project types (including ASP.NET Web Forms, ASP.NET MVC, WPF, WinForms, Silverlight, and Class Libraries).  You can download and install it here. NuGet enables developers who maintain open source projects (for example, .NET projects like Moq, NHibernate, Ninject, StructureMap, NUnit, Windsor, Raven, Elmah, etc) to package up their libraries and register them with an online gallery/catalog that is searchable.  The client-side NuGet tools – which include full Visual Studio integration – make it trivial for any .NET developer who wants to use one of these libraries to easily find and install it within the project they are working on. NuGet handles dependency management between libraries (for example: library1 depends on library2). It also makes it easy to update (and optionally remove) libraries from your projects later. It supports updating web.config files (if a package needs configuration settings). It also allows packages to add PowerShell scripts to a project (for example: scaffold commands). Importantly, NuGet is transparent and clean – and does not install anything at the system level. Instead it is focused on making it easy to manage libraries you use with your projects. Our goal with NuGet is to make it as simple as possible to integrate open source libraries within .NET projects.  NuGet Gallery This week we also launched a beta version of the http://nuget.org web-site – which allows anyone to easily search and browse an online gallery of open source packages available via NuGet.  The site also now allows developers to optionally submit new packages that they wish to share with others.  You can learn more about how to create and share a package here. There are hundreds of open-source .NET projects already within the NuGet Gallery today.  We hope to have thousands there in the future. IIS Express 7.5 Today we are also shipping IIS Express 7.5.  IIS Express is a free version of IIS 7.5 that is optimized for developer scenarios.  It works for both ASP.NET Web Forms and ASP.NET MVC project types. We think IIS Express combines the ease of use of the ASP.NET Web Server (aka Cassini) currently built-into Visual Studio today with the full power of IIS.  Specifically: It’s lightweight and easy to install (less than 5Mb download and a quick install) It does not require an administrator account to run/debug applications from Visual Studio It enables a full web-server feature set – including SSL, URL Rewrite, and other IIS 7.x modules It supports and enables the same extensibility model and web.config file settings that IIS 7.x support It can be installed side-by-side with the full IIS web server as well as the ASP.NET Development Server (they do not conflict at all) It works on Windows XP and higher operating systems – giving you a full IIS 7.x developer feature-set on all Windows OS platforms IIS Express (like the ASP.NET Development Server) can be quickly launched to run a site from a directory on disk.  It does not require any registration/configuration steps. This makes it really easy to launch and run for development scenarios.  You can also optionally redistribute IIS Express with your own applications if you want a lightweight web-server.  The standard IIS Express EULA now includes redistributable rights. Visual Studio 2010 SP1 adds support for IIS Express.  Read my VS 2010 SP1 and IIS Express blog post to learn more about what it enables.  SQL Server Compact Edition 4 Today we are also shipping SQL Server Compact Edition 4 (aka SQL CE 4).  SQL CE is a free, embedded, database engine that enables easy database storage. No Database Installation Required SQL CE does not require you to run a setup or install a database server in order to use it.  You can simply copy the SQL CE binaries into the \bin directory of your ASP.NET application, and then your web application can use it as a database engine.  No setup or extra security permissions are required for it to run. You do not need to have an administrator account on the machine. Just copy your web application onto any server and it will work. This is true even of medium-trust applications running in a web hosting environment. SQL CE runs in-memory within your ASP.NET application and will start-up when you first access a SQL CE database, and will automatically shutdown when your application is unloaded.  SQL CE databases are stored as files that live within the \App_Data folder of your ASP.NET Applications. Works with Existing Data APIs SQL CE 4 works with existing .NET-based data APIs, and supports a SQL Server compatible query syntax.  This means you can use existing data APIs like ADO.NET, as well as use higher-level ORMs like Entity Framework and NHibernate with SQL CE.  This enables you to use the same data programming skills and data APIs you know today. Supports Development, Testing and Production Scenarios SQL CE can be used for development scenarios, testing scenarios, and light production usage scenarios.  With the SQL CE 4 release we’ve done the engineering work to ensure that SQL CE won’t crash or deadlock when used in a multi-threaded server scenario (like ASP.NET).  This is a big change from previous releases of SQL CE – which were designed for client-only scenarios and which explicitly blocked running in web-server environments.  Starting with SQL CE 4 you can use it in a web-server as well. There are no license restrictions with SQL CE.  It is also totally free. Tooling Support with VS 2010 SP1 Visual Studio 2010 SP1 adds support for SQL CE 4 and ASP.NET Projects.  Read my VS 2010 SP1 and SQL CE 4 blog post to learn more about what it enables.  Web Deploy and Web Farm Framework 2.0 Today we are also releasing Microsoft Web Deploy V2 and Microsoft Web Farm Framework V2.  These services provide a flexible and powerful way to deploy ASP.NET applications onto either a single server, or across a web farm of machines. You can learn more about these capabilities from my previous blog posts on them: Introducing the Microsoft Web Farm Framework Automating Deployment with Microsoft Web Deploy Visit the http://iis.net website to learn more and install them. Both are free. Orchard 1.0 Today we are also releasing Orchard v1.0.  Orchard is a free, open source, community based project.  It provides Content Management System (CMS) and Blogging System support out of the box, and makes it possible to easily create and manage web-sites without having to write code (site owners can customize a site through the browser-based editing tools built-into Orchard).  Read these tutorials to learn more about how you can setup and manage your own Orchard site. Orchard itself is built as an ASP.NET MVC 3 application using Razor view templates (and by default uses SQL CE 4 for data storage).  Developers wishing to extend an Orchard site with custom functionality can open and edit it as a Visual Studio project – and add new ASP.NET MVC Controllers/Views to it.  WebMatrix 1.0 WebMatrix is a new, free, web development tool from Microsoft that provides a suite of technologies that make it easier to enable website development.  It enables a developer to start a new site by browsing and downloading an app template from an online gallery of web applications (which includes popular apps like Umbraco, DotNetNuke, Orchard, WordPress, Drupal and Joomla).  Alternatively it also enables developers to create and code web sites from scratch. WebMatrix is task focused and helps guide developers as they work on sites.  WebMatrix includes IIS Express, SQL CE 4, and ASP.NET - providing an integrated web-server, database and programming framework combination.  It also includes built-in web publishing support which makes it easy to find and deploy sites to web hosting providers. You can learn more about WebMatrix from my Introducing WebMatrix blog post this summer.  Visit http://microsoft.com/web to download and install it today. Summary I’m really excited about today’s releases – they provide a bunch of additional value that makes web development with ASP.NET, Visual Studio and the Microsoft Web Server a lot better.  A lot of folks worked hard to share this with you today. On behalf of my whole team – we hope you enjoy them! Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • C# 4: The Curious ConcurrentDictionary

    - by James Michael Hare
    In my previous post (here) I did a comparison of the new ConcurrentQueue versus the old standard of a System.Collections.Generic Queue with simple locking.  The results were exactly what I would have hoped, that the ConcurrentQueue was faster with multi-threading for most all situations.  In addition, concurrent collections have the added benefit that you can enumerate them even if they're being modified. So I set out to see what the improvements would be for the ConcurrentDictionary, would it have the same performance benefits as the ConcurrentQueue did?  Well, after running some tests and multiple tweaks and tunes, I have good and bad news. But first, let's look at the tests.  Obviously there's many things we can do with a dictionary.  One of the most notable uses, of course, in a multi-threaded environment is for a small, local in-memory cache.  So I set about to do a very simple simulation of a cache where I would create a test class that I'll just call an Accessor.  This accessor will attempt to look up a key in the dictionary, and if the key exists, it stops (i.e. a cache "hit").  However, if the lookup fails, it will then try to add the key and value to the dictionary (i.e. a cache "miss").  So here's the Accessor that will run the tests: 1: internal class Accessor 2: { 3: public int Hits { get; set; } 4: public int Misses { get; set; } 5: public Func<int, string> GetDelegate { get; set; } 6: public Action<int, string> AddDelegate { get; set; } 7: public int Iterations { get; set; } 8: public int MaxRange { get; set; } 9: public int Seed { get; set; } 10:  11: public void Access() 12: { 13: var randomGenerator = new Random(Seed); 14:  15: for (int i=0; i<Iterations; i++) 16: { 17: // give a wide spread so will have some duplicates and some unique 18: var target = randomGenerator.Next(1, MaxRange); 19:  20: // attempt to grab the item from the cache 21: var result = GetDelegate(target); 22:  23: // if the item doesn't exist, add it 24: if(result == null) 25: { 26: AddDelegate(target, target.ToString()); 27: Misses++; 28: } 29: else 30: { 31: Hits++; 32: } 33: } 34: } 35: } Note that so I could test different implementations, I defined a GetDelegate and AddDelegate that will call the appropriate dictionary methods to add or retrieve items in the cache using various techniques. So let's examine the three techniques I decided to test: Dictionary with mutex - Just your standard generic Dictionary with a simple lock construct on an internal object. Dictionary with ReaderWriterLockSlim - Same Dictionary, but now using a lock designed to let multiple readers access simultaneously and then locked when a writer needs access. ConcurrentDictionary - The new ConcurrentDictionary from System.Collections.Concurrent that is supposed to be optimized to allow multiple threads to access safely. So the approach to each of these is also fairly straight-forward.  Let's look at the GetDelegate and AddDelegate implementations for the Dictionary with mutex lock: 1: var addDelegate = (key,val) => 2: { 3: lock (_mutex) 4: { 5: _dictionary[key] = val; 6: } 7: }; 8: var getDelegate = (key) => 9: { 10: lock (_mutex) 11: { 12: string val; 13: return _dictionary.TryGetValue(key, out val) ? val : null; 14: } 15: }; Nothing new or fancy here, just your basic lock on a private object and then query/insert into the Dictionary. Now, for the Dictionary with ReadWriteLockSlim it's a little more complex: 1: var addDelegate = (key,val) => 2: { 3: _readerWriterLock.EnterWriteLock(); 4: _dictionary[key] = val; 5: _readerWriterLock.ExitWriteLock(); 6: }; 7: var getDelegate = (key) => 8: { 9: string val; 10: _readerWriterLock.EnterReadLock(); 11: if(!_dictionary.TryGetValue(key, out val)) 12: { 13: val = null; 14: } 15: _readerWriterLock.ExitReadLock(); 16: return val; 17: }; And finally, the ConcurrentDictionary, which since it does all it's own concurrency control, is remarkably elegant and simple: 1: var addDelegate = (key,val) => 2: { 3: _concurrentDictionary[key] = val; 4: }; 5: var getDelegate = (key) => 6: { 7: string s; 8: return _concurrentDictionary.TryGetValue(key, out s) ? s : null; 9: };                    Then, I set up a test harness that would simply ask the user for the number of concurrent Accessors to attempt to Access the cache (as specified in Accessor.Access() above) and then let them fly and see how long it took them all to complete.  Each of these tests was run with 10,000,000 cache accesses divided among the available Accessor instances.  All times are in milliseconds. 1: Dictionary with Mutex Locking 2: --------------------------------------------------- 3: Accessors Mostly Misses Mostly Hits 4: 1 7916 3285 5: 10 8293 3481 6: 100 8799 3532 7: 1000 8815 3584 8:  9:  10: Dictionary with ReaderWriterLockSlim Locking 11: --------------------------------------------------- 12: Accessors Mostly Misses Mostly Hits 13: 1 8445 3624 14: 10 11002 4119 15: 100 11076 3992 16: 1000 14794 4861 17:  18:  19: Concurrent Dictionary 20: --------------------------------------------------- 21: Accessors Mostly Misses Mostly Hits 22: 1 17443 3726 23: 10 14181 1897 24: 100 15141 1994 25: 1000 17209 2128 The first test I did across the board is the Mostly Misses category.  The mostly misses (more adds because data requested was not in the dictionary) shows an interesting trend.  In both cases the Dictionary with the simple mutex lock is much faster, and the ConcurrentDictionary is the slowest solution.  But this got me thinking, and a little research seemed to confirm it, maybe the ConcurrentDictionary is more optimized to concurrent "gets" than "adds".  So since the ratio of misses to hits were 2 to 1, I decided to reverse that and see the results. So I tweaked the data so that the number of keys were much smaller than the number of iterations to give me about a 2 to 1 ration of hits to misses (twice as likely to already find the item in the cache than to need to add it).  And yes, indeed here we see that the ConcurrentDictionary is indeed faster than the standard Dictionary here.  I have a strong feeling that as the ration of hits-to-misses gets higher and higher these number gets even better as well.  This makes sense since the ConcurrentDictionary is read-optimized. Also note that I tried the tests with capacity and concurrency hints on the ConcurrentDictionary but saw very little improvement, I think this is largely because on the 10,000,000 hit test it quickly ramped up to the correct capacity and concurrency and thus the impact was limited to the first few milliseconds of the run. So what does this tell us?  Well, as in all things, ConcurrentDictionary is not a panacea.  It won't solve all your woes and it shouldn't be the only Dictionary you ever use.  So when should we use each? Use System.Collections.Generic.Dictionary when: You need a single-threaded Dictionary (no locking needed). You need a multi-threaded Dictionary that is loaded only once at creation and never modified (no locking needed). You need a multi-threaded Dictionary to store items where writes are far more prevalent than reads (locking needed). And use System.Collections.Concurrent.ConcurrentDictionary when: You need a multi-threaded Dictionary where the writes are far more prevalent than reads. You need to be able to iterate over the collection without locking it even if its being modified. Both Dictionaries have their strong suits, I have a feeling this is just one where you need to know from design what you hope to use it for and make your decision based on that criteria.

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  • Google I/O 2010: Google TV Keynote - Introducing Google TV

    Google I/O 2010: Google TV Keynote - Introducing Google TV Due to licensing and permissions issues, we are unable to show the full Google TV demonstration from the Day 2 keynote at Google I/O. Until we are able to get these permissions, please check out these clips. For Google I/O session videos, presentations, developer interviews and more, go to: code.google.com/io From: GoogleDevelopers Views: 30 1 ratings Time: 06:55 More in Science & Technology

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  • Google I/O 2010: Google TV Keynote - Android Apps On Google TV

    Google I/O 2010: Google TV Keynote - Android Apps On Google TV Due to licensing and permissions issues, we are unable to show the full Google TV demonstration from the Day 2 keynote at Google I/O. Until we are able to get these permissions, please check out these clips. For Google I/O session videos, presentations, developer interviews and more, go to: code.google.com/io From: GoogleDevelopers Views: 8 0 ratings Time: 03:18 More in Science & Technology

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  • Google Chrome Extensions: Launch Event (part 5)

    Google Chrome Extensions: Launch Event (part 5) Video Footage from the Google Chrome Extensions launch event on 12/09/09. Xmarks, ebay and Google Translate present their experience developing an extension for Google Chrome. From: GoogleDevelopers Views: 3037 18 ratings Time: 10:30 More in Science & Technology

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  • What is PubSubHubbub?

    What is PubSubHubbub? An overview of pubsubhubbub, a simple, open, web-hook-based pubsub protocol & open source reference implementation. Brett Slatkin and Brad Fitzpatrick demonstrate what pubsubhubbub is and how it works. For more information, visit pubsubhubbub.googlecode.com From: GoogleDevelopers Views: 23753 112 ratings Time: 03:20 More in Science & Technology

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