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  • How to reference {{outlet}} in Ember.CollectionView's itemView

    - by ceed
    I am new to ember and ran into a problem and could not find an answer online. I have a collectionView App.MyView = Ember.CollectionView.extend({ itemViewClass: 'App.MyViewItem', contentBinding: 'controller' }); and the itemViewClass App.MyViewItem = Ember.View.extend({ templateName: 'mytemplate' }); the template looks like that: <div {{action 'select' view.content}}>{{view.content.name}}</div> {{outlet detail}} </div> This produces the content list just fine. In the controller, I have an action: select: function(evt){ this.transitionToRoute('item', evt); } What I want to do is to transition to a nested route when selecting the item (which works fine) and also load more data of the selected item into {{outlet detail}}. While I can load the content of the "item" route into an outlet of e.g. application.hbs, I don't know how to reference the outlet of the selected collectionView item so that the detailed contents are displayed within the existing view. I tried to use: this.render('item', { outlet: 'detail', into: '????' }); within the item Route, but I don't know how to reference the collectionview item template. Maybe there's also a much easier way of loading more data from an item in the item's view (while changing the route at the same time). Any help would be appreciated.

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  • Integration testing - can it be done right?

    - by Max
    I used TDD as a development style on some projects in the past two years, but I always get stuck on the same point: how can I test the integration of the various parts of my program? What I am currently doing is writing a testcase per class (this is my rule of thumb: a "unit" is a class, and each class has one or more testcases). I try to resolve dependencies by using mocks and stubs and this works really well as each class can be tested independently. After some coding, all important classes are tested. I then "wire" them together using an IoC container. And here I am stuck: How to test if the wiring was successfull and the objects interact the way I want? An example: Think of a web application. There is a controller class which takes an array of ids, uses a repository to fetch the records based on these ids and then iterates over the records and writes them as a string to an outfile. To make it simple, there would be three classes: Controller, Repository, OutfileWriter. Each of them is tested in isolation. What I would do in order to test the "real" application: making the http request (either manually or automated) with some ids from the database and then look in the filesystem if the file was written. Of course this process could be automated, but still: doesn´t that duplicate the test-logic? Is this what is called an "integration test"? In a book i recently read about Unit Testing it seemed to me that integration testing was more of an anti-pattern?

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  • Reload a UITable on the fly when editing a UITextField inside one of the cells

    - by Saze
    I have a UITable containing some customs UITableCells. Those cells contain a few UILabels and a UITextField. The datasource of the table comes from a main controller's property. (This controller is also the delegate and the dataSource for the table). Here's a simplified screenshot of the UI: Now, I need to update "on the fly" the content of all the UILabels when the user edits one of the UITextFields. To do so, at the I am listening to the "Editing Changed" event at the UITextField level. This triggers the following action: - (IBAction) editChangeHandler: (id) sender { MyAppDelegate *delegate = [[UIApplication sharedApplication] delegate]; [[delegate.viewController.myDataSourceArray objectAtIndex:self.rowIndex] setANumber: [theTextField.text intValue]]; [delegate.viewController reloadRows]; } The reloadRows method in the viewController is as such: - (void) reloadRows { NSLog(@"called reloadRows"); //perform some calculations on the data source objects here... [theUITable reloadData]; } My problem here is that whenever the user changes the value in the field, the reloadRows method is successfully called, so is apparently the reloadData but it also causes the keyboard to be dismissed. So in the end, the user can only touch one key when editing the TextField before the keyboard is dismissed and the table reloaded. Does anybody knows a solution to this or have experienced the same issue?

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  • best way to avoid sql injection

    - by aauser
    I got similar domain model 1) User. Every user got many cities. @OneToMany(targetEntity=adv.domain.City.class...) 2) City. Every city got many districts @OneToMany(targetEntity=adv.domain.Distinct.class) 3) Distintc My goal is to delete distinct when user press delete button in browser. After that controller get id of distinct and pass it to bussiness layer. Where method DistinctService.deleteDistinct(Long distinctId) should delegate deliting to DAO layer. So my question is where to put security restrictions and what is the best way to accomplish it. I want to be sure that i delete distinct of the real user, that is the real owner of city, and city is the real owner of distinct. So nobody exept the owner can't delete ditinct using simple url like localhost/deleteDistinct/5. I can get user from httpSession in my controller and pass it to bussiness layer. After that i can get all cities of this user and itrate over them to be sure, that of the citie.id == distinct.city_id and then delete distinct. But it's rather ridiculous in my opinion. Also i can write sql query like this ... delete from t_distinct where t_distinct.city_id in (select t_city.id from t_city left join t_user on t_user.id = t_city.owner_id where t_user.id = ?) and t_distinct.id = ? So what is the best practice to add restrictions like this. I'm using Hibernate, Spring, Spring MVC by the way.. Thank you

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  • MVC and binding to List of Checkboxes

    - by Josh
    Here is my problem. I have a list of models that are displayed to the user. On the left is a checkbox for each model to indicate that the user wants to choose this model (in this case, we're building products a user can add to their shopping cart). The model has no concept of being chosen...it strictly has information about the product in question. I've talked with a few other developers after having gone through and the best I could come up with is getting the formcollection and string parsing the key values to determine whether the checkbox is checked or not. This doesn't seem ideal. I was thinking there would be something more strongly bound, but I can't figure out a way to do it. I tried creating another model that had a boolean property to represent being checked and a property of the model and passing a list of that model type to the view and creating a ActionResult on the controller that accepts a list of the new model / checked property, but it comes back null. Am I just thinking too much like web forms and should just continue on with parsing checkbox values? Here's what I've done for wrapping the models inside a collection: public class SelectableCollection[T] : IList[T] {} public class SelectableTrack{ public bool IsChecked{get;set;} public bool CurrentTrack{get;set;} } For the view, I inherit from ViewPage[SelectableCollection[SelectableTrack]] For the controller, I have this as the ActionResult: [HttpPost] public ActionResult SelectTracks(SelectableCollection sc) { return new EmptyResult(); } But when I break inside the ActionResult, the collection is null. Any reason why it isn't coming through?

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  • Should I re-use UI elements across view controllers?

    - by Endemic
    In the iPhone app I'm currently working on, I'd like two navigation controllers (I'll call them A and B) to have toolbars that are identical in appearance and function. The toolbar in question will look like this: [(button) (flexible-space) (label)] For posterity's sake, the label is actually a UIBarButtonItem with a custom view. My design requires that A always appear directly before B on the navigation stack, so B will never be loaded without A having been loaded. Given this layout, I started wondering, "Is it worth it to re-use A's toolbar items in B's toolbar?" As I see it, my options are: 1. Don't worry about re-use, create the toolbar items twice 2. Create the toolbar items in A and pass them to B in a custom initializer 3. Use some more obscure method that I haven't thought of to hold the toolbar constant when pushing a view controller As far as I can see, option 1 may violate DRY, but guarantees that there won't be any confusion on the off chance that (for example) the button may be required to perform two different (no matter how similar) functions for either view controller in future versions of the app. Were that to happen, options 2 or 3 would require the target-action of the button to change when B is loaded and unloaded. Even if the button were never required to perform different functions, I'm not sure what its proper target would be under option 2. All in all, it's not a huge problem, even if I have to go with option 1. I'm probably overthinking this anyway, trying to apply the dependency injection pattern where it's not appropriate. I just want to know the best practice should this situation arise in a more extreme form, like if a long chain of view controllers need to use identical (in appearance and function) UI elements.

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  • Rails HTML Table update fields in mongo with AJAX

    - by qwexar
    I'm building a Rails app backed by mongodb using mongoid. It's a one page app, with a HTML table, every field for every row of which, needs to be editable without refreshing the page. This is your usual Rails view ( like many in rails casts ) showing a table with rows and columns containing data. For example. I'm showing cars, and showing their make, model and notes They way I'm doing this is by appending _id of a mongo document to every column and marking it's field name in html id too. Then I pick up the value for $("#id") and send it to rails controller via AJAX and run @car.update_attributes method accordingly. Currently, one of my rows looks like this. <tr> <td id=<%= car.id %>_make> <%= car.make %> </td> <td id=<%= car.id %>_model> <%= car.model %> </td> <td id=<%= car.id %>_notes> <%= car.notes %> </td> </tr> // my function which is called onChange for every column function update_attributes(id){ var id = id.split[0]; var attribute = id.split[1]; $.ajax("sending id and attribute to rails controller"); } Is there any built it Rails magic which would let me update only a field in a model without refreshing the page? or. Is there a Rails plugin for this?

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  • How to use the values from session variables in jsp pages that got saved using @Scope("session") in the mvc controllers

    - by droidsites
    Doing a web site using spring mvc. I added a SignupController to handle all the sign up related requests. Once user signup I am adding that to a session using @Scope("session"). Below is the SignupController code, SignupController.java @Controller @Scope("session") public class SignupController { @Autowired SignupServiceInter signUpService; private static final Logger logger = Logger.getLogger(SignupController.class); private String sessionUser; @RequestMapping("/SignupService") public ModelAndView signUp(@RequestParam("userid") String userId, @RequestParam("password") String password,@RequestParam("mailid") String emailId){ logger.debug(" userId:"+userId+"::Password::"+password+"::"); String signupResult; try { signUpService.registerUser(userId, password,emailId); sessionUser = userId; //adding the sign up user to the session return new ModelAndView("userHomePage","loginResult","Success"); //Navigate to user Home page if everything goes right } catch (UserExistsException e) { signupResult = e.toString(); return new ModelAndView("signUp","loginResult", signupResult); //Navigate to signUp page back if user does not exist } } } I am using "sessionUser" variable to store the signed up User Id. My understanding is that when I use @Scope("session") for the controller all the instance variables will added to HttpSession. So by that understanding I tried to access this "SessionUser" in userHomePage.jsp as, userHomepage.jsp Welcome to <%=session.getAttribute("sessionUser")%> But it throws null. So my question is how to use the values from session variables in jsp pages that got saved using @Scope("session") in the mvc controllers. Note: My work around is that pass that signed User Id to jsp page through ModelAndView, but it seems passing the value like these among the pages takes me back to managing state among pages using QueryStrings days.

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  • undefined method `model_name' for NilClass:Class - Rails application

    - by user1270259
    So I have seen other articles here on stack about this and a lot of the time people are not doing @post = post.new. I read some where to use the plural...?? any ways I am getting this error on my discussion code: Discussion Controller class DiscussionsController < ApplicationController def index @discussion = Discussion.new @discussions = Discussion.all end def create @discussion = Discussion.create(params[:discussion]) if @discussion.save redirect_to tasks_path, :flash => {:success => 'Created a new discussion'} else redirect_to tasks_path, :flash => {:error => 'Failed to create a discussion'} end end end Discussion Form <%= form_for @discussion do |f| %> <p><%= f.label :title %> <%= f.text_field :title %></p> <p><%= f.label :content %> <%= f.text_area :content %></p> <% end %> Discussion Routes resources :discussions do resources :comments end Now as far as I know I am doing this right, because I have a task form set up essentially the same way - but I have looked at my code for hours and have googled and tried other examples and now i see this: undefined method `model_name' for NilClass:Class Extracted source (around line #1): 1: <%= form_for @discussion do |f| %> 2: 3: <p><%= f.label :title %> 4: <%= f.text_field :title %></p> Which should mean that I am missing something from my controller.....is it as asilly as a spelling mistake? .

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  • Import Excel into Rails app

    - by Jack
    Hi, I am creating a small rails app for personal use and would like to be able to upload excel files to later be validated and added to the database. I had this working previously with csv files, but this has since become impractical. Does anyone know of a tutorial for using the roo or spreadsheet gem to upload the file, display the contents to the user and then add to the database (after validating)? I know this is quite specific, but I want to work through this step by step. All I have so far is an 'import' view: <% form_for :dump, :url=>{:controller=>"students", :action=>"student_import"}, :html => { :multipart => true } do |f| -%> Select an Excel File : <%= f.file_field :excel_file -%> <%= submit_tag 'Submit' -%> <% end -%> But have no idea how to access this uploaded file in the controller. Any suggestions/help would be welcomed. Thanks

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  • Can I use a UINavigationController as the detail view of a UISplitViewController?

    - by B Sweigard
    I'm running into a problem with an iPad app where I would like to have UINavigationControllers in both of the views within a UISplitView. I've looked through other similar questions here, but most link to a tutorial online that doesn't completely solve the problem. Here's a 2-minute walkthrough to re-create the problem I'm having: Create a New Project in XCode, starting from the Split View-based Application template. Add the following NSLog statement as the first line within the DetailViewController's willHideViewController method: NSLog(@"toolbar: %@", toolbar); If you run the application now, the log will show that the DetailViewController's toolbar is alive and well. Now... Open MainWindow.xib and expand the SplitViewController. Drag a Navigation Controller from the library on top of the DetailViewController. Expand the new Navigation Controller and change the class of the UIViewController within to a DetailViewController. Ctrl-drag from the SplitViewController to the DetailViewController and assign it as the delegate. Save MainWindow.xib and run the app again. At this point, the detail view has a navigation bar and an empty toolbar. If you view the logs, you should find that the toolbar is null. Why is this? Am I missing some sort of connection in Interface Builder? Is the navigation bar the problem for some reason? Unlike the tutorial at http://www.cimgf.com/2010/05/24/fixing-the-uisplitviewcontroller-template/, I would like to keep both the navigation bar and the toolbar (preferably with the toolbar at the top when in portrait and not visible when in landscape), so that I still have a functional "Back" button when the iPad is in portrait orientation. Does anyone have any suggestions for fixing this problem? An example project with this sort of set-up would be ideal.

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  • Destroy? Delete? What's going on here? Rails 2.3.5

    - by Steve
    I am new to rails. My rails version is 2.3.5. I found usage like: In controller, a destroy method is defined and in view, you can use :action = "delete" to fire that method. Isn't the action name has to be the same as the method name? Why delete is mapped to destroy? Again, in my controller, I define a method called destroy to delete a record. In a view, I have <%= link_to "remove", :action = 'destroy', :id = myrecord %. But it never works in practice. Every time I press the remove link, it redirects me to the show view, showing the record's content. I am pretty sure that my destroy method is: def destroy @myobject = MyObject.find(params[:id]) @myobject.destroy @redirect_to :action = 'index' end If I change the method name from destroy to something like remove_me and change the action name to remove_me in the view, everything works as expected. In the above two wired problems, I am sure there is no tricky rountting set in my configuration. All in all, seems the destroy and delete are mysterious keywords in rails. Anyone can explain this to me? Thank you very much.

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  • creating xml from database

    - by Prady
    hi, I am creating an xml from salesforce database, Everything works fine except when there is a & in the data which is been fetched. <apex:page contenttype="text/xml" > controller="Test2ab" > <data > wiki-section="Timeline"> <apex:repeat > value="{!lsttask}" var="e" > <event > start="{!e.ActivityDate}" title= > "{!e.Subject}"> <apex:outputText > value="{!e.Subject}" /> </event> > </apex:repeat> </data></apex:page> and in the controller i am just querying > lsttask =[Select OwnerId,WhoId,Status,Subject,ActivityDate from Task where Status = 'Completed' Order By ActivityDate Desc]; How can i use an escape for the value retrieved from the database Thanks Prady

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  • UIImageView not displaying image when property is set too early

    - by Undeadlegion
    I have an image I want to display inside a UIView. In Interface Builder, the UIView is the root and a UIImageView is its child. The view is connected to view controller's view outlet, and the image view is connected to the image view outlet: @property (nonatomic, retain) IBOutlet UIImageView *imageView; If I try to set the image property of UIImageView before it's visible, the image doesn't show up. TestView *testView = [[TestView alloc] initWithNibName:@"TestView" bundle:nil]; testview.imageView.image = [logos objectAtIndex:indexPath.row]; [self.navigationController pushViewController:testView animated:YES]; If, however, I pass the image to the controller and set the image property in view did load, the image becomes visible. TestView *testView = [[TestView alloc] initWithNibName:@"TestView" bundle:nil]; testview.image = [logos objectAtIndex:indexPath.row]; [self.navigationController pushViewController:testView animated:YES]; - (void)viewDidLoad { [super viewDidLoad]; imageView.image = image; } What is causing the image to not show up in the first scenario?

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  • I can't find the homepage for my ASP.NET MVC site :(

    - by Pure.Krome
    Hi folks, really simple question here. when I remove the default route, I returns an empty page to the browser :- routes.MapRoute( "Default", // Route name "{controller}/{action}/{id}", // URL with parameters new { controller = "Home", action = "Index", id = UrlParameter.Optional } ); Now before everyone starts shouting "that's because that's the default route to access all action methods, etc.." .. i know that. My question is - what code / routes does the default framework try and call .. which makes that Default Route get used/kick in? Why? I don't wish to make that my default route regex (don't ask why - this is some R&D) but I still need the main home page .. ie. Home/Index . If i try and just add that route, it doesn't get called and an empty page is returned. So -- what does the framework try and call when a user doesn't provide any urls? It's like there's some secret default document stuff set up? Cheers :)

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  • How to add a checkbox for each row in Rails 3.2 index page?

    - by user938363
    We would like to add a checkbox to each row on Rails index page to flag for the row. This checkbox is not part of the object (no checkbox boolean in database). When the index page shows, a user can check the box to trigger an event for the row in following process: #objects/checkbox_index.html.erb <table> <tr> <th>CheckBox</th> <th>Object Name</th> <th>Object ID</th> </tr> <%= @objects.each do |obj| %> <tr> <td><%= checkbox %></td> <td><%= obj.name %></td> <td><%= obj.id %></td> </tr> <% end %> </table> In controller, the process will be like this: @objects.each do |obj| some_event if obj.checked end There are a couple of questions we don't quite understand: 1. How to declare an array checkbox variable on the form and link it to each row of obj? We have been using `attr_accessor` to declare var for a form. 2. How to retrieve each row on checkbox_index form and pass them back to controller? We are using simple_form for new/edit. Can anyone point me towards any good examples of this sort of behavior, or suggest what we should be thinking about? Many Thanks.

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  • expected ":" before "]" token + confused by earlier errors, bailing out

    - by Colby Bookout
    Ok so im at my wit's end here. I have tried every imaginable thing to get rid of these errors heres my code: - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { // Navigation logic may go here. Create and push another view controller. /* //<#DetailViewController#> *detailViewController = [[<#DetailViewController#> alloc] initWithNibName:@"<#Nib name#>" bundle:nil]; // ... // Pass the selected object to the new view controller. [self.navigationController pushViewController:detailViewController animated:YES]; [detailViewController release]; */ NSInteger row = [indexPath.row]; if (self.nameExcerptPage == nil) { NameOTWexcerpt *nameExcerptPageDetail = [[nameExcerptPage alloc] initWithNibName:@"NameOTWexcerpt" bundle:nil]; self.nameExcerptPage = nameExcerptPageDetail; [nameExcerptPageDetail release]; nameExcerptPage.title = [NSString stringWithFormat:@"%&", [TheBookNavTabs objectAtIndex:row]]; Rothfuss_ReaderAppDelegate *delegate = [[UIApplication sharedApplication] delegate]; [delegate.SecondTableViewController pushViewController:TheBookNavTabs animated:YES]; } } and the error appears where it says "NSInteger row = [indexPath.row]; please help! thanks!

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  • Multiple/Sub quries with codeigniter

    - by user1011713
    I just started with Codeigniter and this is driving me nuts. I have a query that determines whether a user has bought any programs. I then have to use that program's type category to run and determine how many times he or she has recorded a query in another table. Sorry for the confusion but the code hopefully makes sense. I'm having problem returning the two arrays from my Model to my Controller to onto the view obviously. function specificPrograms() { $specific_sql = $this->db->query("SELECT program,created FROM `assessment` WHERE uid = $this->uid"); if($specific_sql->num_rows() > 0) { foreach ($specific_sql->result() as $specific) { $data[] = $specific; $this->type = $specific->program; } return $data; } $sub_sql = $this->db->query("SELECT id FROM othertable WHERE user_id_fk = $this->uid and type = '$this->type'"); if($sub_sql->num_rows() > 0) { foreach ($sub_sql->result() as $otherp) { $data[] = $otherp; } return $data; } } Then in my Controller I have, $data['specific'] = $this->user_model->specificPrograms(); $data['otherp'] = $this->user_model->specificPrograms(); Thanks for any help.

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  • Variable text in links with knockout

    - by Gepser
    I'm generating a list of links and they have not the same text but I don't know how to put a text with knockout. This is what I have: <a data-bind="attr: { href: 'Controller/Method/' + Id, 'Title': CurrentTask }"> <!-- I need the name of the CurrentTask here--> CurrentTask </a> So, the text I want to show appears only in the "alt" property but not in the text of the link. It works but I need that the name of the CurrentTask be the link and now it's just showing me everything like this: <a href...>CurrentTask</a> <a href...>CurrentTask</a> <a href...>CurrentTask</a> <a href...>CurrentTask</a> and I need this <a href...>I get this data from de controller</a> <a href...>Sometext</a> <a href...>OtherText</a> <a href...>Anything</a>

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  • Calling a view from the second project

    - by user3128303
    I have 2 projects in the Solution (asp.net-mvc). The first project is main, the other project (1 simple controller and views (Index, Layout). I want directly from the menu in the project 1, to refer to the Index view of the second project. I added a reference but I do not know what to do. Someone help? Ps: Sorry for my english. Project 1 _Layout.cshtml <!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <title>@ViewBag.Title</title> <link href="@Url.Content("~/Content/Site.css")" rel="stylesheet" type="text/css" /> <script src="@Url.Content("~/Scripts/jquery-1.5.1.min.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/modernizr-1.7.min.js")" type="text/javascript"></script> </head> <body> <div> <nav> <a href="@Url.Content("~")" id="current">Home</a> <a href="@Url.Content( /* via a link you want to get to the index from Project 2 */)">TEST</a> </nav> </div> <div id="main"> @RenderBody() </div> <div id="footer"> </div> </body> </html> Project 2 HomeController.cs namespace Panel.Controllers { public class HomeController : Controller { public ActionResult Index() { return View(); } } }

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  • How to set the delay between update queries in Mysql so that every query get executed succesfully?

    - by OM The Eternity
    Hi All I have to the Update query mulitple times for different parameters using for loop in my PHP Script, now the problem Is Whenever I do it, only my last query get executed, all the previous queries seems to be skipped. the loop goes like this: foreach($cntrlflagset as $cntrlordoc => $cntrlorflag){ for($t=0;$t<count($cntrlorflag);$t++){ $userlvl = "controller"; $docflag = 1; $postfix = "created"; $createdoc->updatedocseeflags($cntrlorflag[$t],$docflag,$cntrlordoc,$postfix,$userlvl); $docflag = 2; $postfix = "midlvl"; $createdoc->updatedocseeflags($cntrlorflag[$t],$docflag,$cntrlordoc,$postfix,$userlvl); } } Here, the called function $createdoc-updatedocseeflags($cntrlorflag[$t],$docflag,$cntrlordoc,$postfix,$userlvl); Contains the Update query: $query = "UPDATE tbl_docuserstatus SET"; //if($flag != ""){ $query .= " docseeflag_".$postfix." = '".$flag."'"; //} $query .= " WHERE doc_id = '".$doc_id."' AND user_id = '".$user_id."'"; if($userlvl == "midlvl"){ $query .= " AND doc_midlvluser = '1'"; }elseif($userlvl == "finallvl"){ $query .= " AND doc_finallvluser = '1'"; }elseif($userlvl == "creator"){ $query .= " AND doc_creator = '1'"; }elseif($userlvl == "controller"){ $query .= " AND doc_controller = '1'"; }elseif($docarchive == 1){ $query .= " AND doc_controller = '1'"; } So could some one tell me, How to set the delay between update queries in Mysql so that every query get executed succesfully? Thanks In Advance

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  • Use IIS Application Initialization for keeping ASP.NET Apps alive

    - by Rick Strahl
    I've been working quite a bit with Windows Services in the recent months, and well, it turns out that Windows Services are quite a bear to debug, deploy, update and maintain. The process of getting services set up,  debugged and updated is a major chore that has to be extensively documented and or automated specifically. On most projects when a service is built, people end up scrambling for the right 'process' to use for administration. Web app deployment and maintenance on the other hand are common and well understood today, as we are constantly dealing with Web apps. There's plenty of infrastructure and tooling built into Web Tools like Visual Studio to facilitate the process. By comparison Windows Services or anything self-hosted for that matter seems convoluted.In fact, in a recent blog post I mentioned that on a recent project I'd been using self-hosting for SignalR inside of a Windows service, because the application is in fact a 'service' that also needs to send out lots of messages via SignalR. But the reality is that it could just as well be an IIS application with a service component that runs in the background. Either way you look at it, it's either a Windows Service with a built in Web Server, or an IIS application running a Service application, neither of which follows the standard Service or Web App template.Personally I much prefer Web applications. Running inside of IIS I get all the benefits of the IIS platform including service lifetime management (crash and restart), controlled shutdowns, the whole security infrastructure including easy certificate support, hot-swapping of code and the the ability to publish directly to IIS from within Visual Studio with ease.Because of these benefits we set out to move from the self hosted service into an ASP.NET Web app instead.The Missing Link for ASP.NET as a Service: Auto-LoadingI've had moments in the past where I wanted to run a 'service like' application in ASP.NET because when you think about it, it's so much easier to control a Web application remotely. Services are locked into start/stop operations, but if you host inside of a Web app you can write your own ticket and control it from anywhere. In fact nearly 10 years ago I built a background scheduling application that ran inside of ASP.NET and it worked great and it's still running doing its job today.The tricky part for running an app as a service inside of IIS then and now, is how to get IIS and ASP.NET launched so your 'service' stays alive even after an Application Pool reset. 7 years ago I faked it by using a web monitor (my own West Wind Web Monitor app) I was running anyway to monitor my various web sites for uptime, and having the monitor ping my 'service' every 20 seconds to effectively keep ASP.NET alive or fire it back up after a reload. I used a simple scheduler class that also includes some logic for 'self-reloading'. Hacky for sure, but it worked reliably.Luckily today it's much easier and more integrated to get IIS to launch ASP.NET as soon as an Application Pool is started by using the Application Initialization Module. The Application Initialization Module basically allows you to turn on Preloading on the Application Pool and the Site/IIS App, which essentially fires a request through the IIS pipeline as soon as the Application Pool has been launched. This means that effectively your ASP.NET app becomes active immediately, Application_Start is fired making sure your app stays up and running at all times. All the other features like Application Pool recycling and auto-shutdown after idle time still work, but IIS will then always immediately re-launch the application.Getting started with Application InitializationAs of IIS 8 Application Initialization is part of the IIS feature set. For IIS 7 and 7.5 there's a separate download available via Web Platform Installer. Using IIS 8 Application Initialization is an optional install component in Windows or the Windows Server Role Manager: This is an optional component so make sure you explicitly select it.IIS Configuration for Application InitializationInitialization needs to be applied on the Application Pool as well as the IIS Application level. As of IIS 8 these settings can be made through the IIS Administration console.Start with the Application Pool:Here you need to set both the Start Automatically which is always set, and the StartMode which should be set to AlwaysRunning. Both have to be set - the Start Automatically flag is set true by default and controls the starting of the application pool itself while Always Running flag is required in order to launch the application. Without the latter flag set the site settings have no effect.Now on the Site/Application level you can specify whether the site should pre load: Set the Preload Enabled flag to true.At this point ASP.NET apps should auto-load. This is all that's needed to pre-load the site if all you want is to get your site launched automatically.If you want a little more control over the load process you can add a few more settings to your web.config file that allow you to show a static page while the App is starting up. This can be useful if startup is really slow, so rather than displaying blank screen while the user is fiddling their thumbs you can display a static HTML page instead: <system.webServer> <applicationInitialization remapManagedRequestsTo="Startup.htm" skipManagedModules="true"> <add initializationPage="ping.ashx" /> </applicationInitialization> </system.webServer>This allows you to specify a page to execute in a dry run. IIS basically fakes request and pushes it directly into the IIS pipeline without hitting the network. You specify a page and IIS will fake a request to that page in this case ping.ashx which just returns a simple OK string - ie. a fast pipeline request. This request is run immediately after Application Pool restart, and while this request is running and your app is warming up, IIS can display an alternate static page - Startup.htm above. So instead of showing users an empty loading page when clicking a link on your site you can optionally show some sort of static status page that says, "we'll be right back".  I'm not sure if that's such a brilliant idea since this can be pretty disruptive in some cases. Personally I think I prefer letting people wait, but at least get the response they were supposed to get back rather than a random page. But it's there if you need it.Note that the web.config stuff is optional. If you don't provide it IIS hits the default site link (/) and even if there's no matching request at the end of that request it'll still fire the request through the IIS pipeline. Ideally though you want to make sure that an ASP.NET endpoint is hit either with your default page, or by specify the initializationPage to ensure ASP.NET actually gets hit since it's possible for IIS fire unmanaged requests only for static pages (depending how your pipeline is configured).What about AppDomain Restarts?In addition to full Worker Process recycles at the IIS level, ASP.NET also has to deal with AppDomain shutdowns which can occur for a variety of reasons:Files are updated in the BIN folderWeb Deploy to your siteweb.config is changedHard application crashThese operations don't cause the worker process to restart, but they do cause ASP.NET to unload the current AppDomain and start up a new one. Because the features above only apply to Application Pool restarts, AppDomain restarts could also cause your 'ASP.NET service' to stop processing in the background.In order to keep the app running on AppDomain recycles, you can resort to a simple ping in the Application_End event:protected void Application_End() { var client = new WebClient(); var url = App.AdminConfiguration.MonitorHostUrl + "ping.aspx"; client.DownloadString(url); Trace.WriteLine("Application Shut Down Ping: " + url); }which fires any ASP.NET url to the current site at the very end of the pipeline shutdown which in turn ensures that the site immediately starts back up.Manual Configuration in ApplicationHost.configThe above UI corresponds to the following ApplicationHost.config settings. If you're using IIS 7, there's no UI for these flags so you'll have to manually edit them.When you install the Application Initialization component into IIS it should auto-configure the module into ApplicationHost.config. Unfortunately for me, with Mr. Murphy in his best form for me, the module registration did not occur and I had to manually add it.<globalModules> <add name="ApplicationInitializationModule" image="%windir%\System32\inetsrv\warmup.dll" /> </globalModules>Most likely you won't need ever need to add this, but if things are not working it's worth to check if the module is actually registered.Next you need to configure the ApplicationPool and the Web site. The following are the two relevant entries in ApplicationHost.config.<system.applicationHost> <applicationPools> <add name="West Wind West Wind Web Connection" autoStart="true" startMode="AlwaysRunning" managedRuntimeVersion="v4.0" managedPipelineMode="Integrated"> <processModel identityType="LocalSystem" setProfileEnvironment="true" /> </add> </applicationPools> <sites> <site name="Default Web Site" id="1"> <application path="/MPress.Workflow.WebQueueMessageManager" applicationPool="West Wind West Wind Web Connection" preloadEnabled="true"> <virtualDirectory path="/" physicalPath="C:\Clients\…" /> </application> </site> </sites> </system.applicationHost>On the Application Pool make sure to set the autoStart and startMode flags to true and AlwaysRunning respectively. On the site make sure to set the preloadEnabled flag to true.And that's all you should need. You can still set the web.config settings described above as well.ASP.NET as a Service?In the particular application I'm working on currently, we have a queue manager that runs as standalone service that polls a database queue and picks out jobs and processes them on several threads. The service can spin up any number of threads and keep these threads alive in the background while IIS is running doing its own thing. These threads are newly created threads, so they sit completely outside of the IIS thread pool. In order for this service to work all it needs is a long running reference that keeps it alive for the life time of the application.In this particular app there are two components that run in the background on their own threads: A scheduler that runs various scheduled tasks and handles things like picking up emails to send out outside of IIS's scope and the QueueManager. Here's what this looks like in global.asax:public class Global : System.Web.HttpApplication { private static ApplicationScheduler scheduler; private static ServiceLauncher launcher; protected void Application_Start(object sender, EventArgs e) { // Pings the service and ensures it stays alive scheduler = new ApplicationScheduler() { CheckFrequency = 600000 }; scheduler.Start(); launcher = new ServiceLauncher(); launcher.Start(); // register so shutdown is controlled HostingEnvironment.RegisterObject(launcher); }}By keeping these objects around as static instances that are set only once on startup, they survive the lifetime of the application. The code in these classes is essentially unchanged from the Windows Service code except that I could remove the various overrides required for the Windows Service interface (OnStart,OnStop,OnResume etc.). Otherwise the behavior and operation is very similar.In this application ASP.NET serves two purposes: It acts as the host for SignalR and provides the administration interface which allows remote management of the 'service'. I can start and stop the service remotely by shutting down the ApplicationScheduler very easily. I can also very easily feed stats from the queue out directly via a couple of Web requests or (as we do now) through the SignalR service.Registering a Background Object with ASP.NETNotice also the use of the HostingEnvironment.RegisterObject(). This function registers an object with ASP.NET to let it know that it's a background task that should be notified if the AppDomain shuts down. RegisterObject() requires an interface with a Stop() method that's fired and allows your code to respond to a shutdown request. Here's what the IRegisteredObject::Stop() method looks like on the launcher:public void Stop(bool immediate = false) { LogManager.Current.LogInfo("QueueManager Controller Stopped."); Controller.StopProcessing(); Controller.Dispose(); Thread.Sleep(1500); // give background threads some time HostingEnvironment.UnregisterObject(this); }Implementing IRegisterObject should help with reliability on AppDomain shutdowns. Thanks to Justin Van Patten for pointing this out to me on Twitter.RegisterObject() is not required but I would highly recommend implementing it on whatever object controls your background processing to all clean shutdowns when the AppDomain shuts down.Testing it outI'm still in the testing phase with this particular service to see if there are any side effects. But so far it doesn't look like it. With about 50 lines of code I was able to replace the Windows service startup to Web start up - everything else just worked as is. An honorable mention goes to SignalR 2.0's oWin hosting, because with the new oWin based hosting no code changes at all were required, merely a couple of configuration file settings and an assembly directive needed, to point at the SignalR startup class. Sweet!It also seems like SignalR is noticeably faster running inside of IIS compared to self-host. Startup feels faster because of the preload.Starting and Stopping the 'Service'Because the application is running as a Web Server, it's easy to have a Web interface for starting and stopping the services running inside of the service. For our queue manager the SignalR service and front monitoring app has a play and stop button for toggling the queue.If you want more administrative control and have it work more like a Windows Service you can also stop the application pool explicitly from the command line which would be equivalent to stopping and restarting a service.To start and stop from the command line you can use the IIS appCmd tool. To stop:> %windir%\system32\inetsrv\appcmd stop apppool /apppool.name:"Weblog"and to start> %windir%\system32\inetsrv\appcmd start apppool /apppool.name:"Weblog"Note that when you explicitly force the AppPool to stop running either in the UI (on the ApplicationPools page use Start/Stop) or via command line tools, the application pool will not auto-restart immediately. You have to manually start it back up.What's not to like?There are certainly a lot of benefits to running a background service in IIS, but… ASP.NET applications do have more overhead in terms of memory footprint and startup time is a little slower, but generally for server applications this is not a big deal. If the application is stable the service should fire up and stay running indefinitely. A lot of times this kind of service interface can simply be attached to an existing Web application, or if scalability requires be offloaded to its own Web server.Easier to work withBut the ultimate benefit here is that it's much easier to work with a Web app as opposed to a service. While developing I can simply turn off the auto-launch features and launch the service on demand through IIS simply by hitting a page on the site. If I want to shut down an IISRESET -stop will shut down the service easily enough. I can then attach a debugger anywhere I want and this works like any other ASP.NET application. Yes you end up on a background thread for debugging but Visual Studio handles that just fine and if you stay on a single thread this is no different than debugging any other code.SummaryUsing ASP.NET to run background service operations is probably not a super common scenario, but it probably should be something that is considered carefully when building services. Many applications have service like features and with the auto-start functionality of the Application Initialization module, it's easy to build this functionality into ASP.NET. Especially when combined with the notification features of SignalR it becomes very, very easy to create rich services that can also communicate their status easily to the outside world.Whether it's existing applications that need some background processing for scheduling related tasks, or whether you just create a separate site altogether just to host your service it's easy to do and you can leverage the same tool chain you're already using for other Web projects. If you have lots of service projects it's worth considering… give it some thought…© Rick Strahl, West Wind Technologies, 2005-2013Posted in ASP.NET  SignalR  IIS   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Introducing Data Annotations Extensions

    - by srkirkland
    Validation of user input is integral to building a modern web application, and ASP.NET MVC offers us a way to enforce business rules on both the client and server using Model Validation.  The recent release of ASP.NET MVC 3 has improved these offerings on the client side by introducing an unobtrusive validation library built on top of jquery.validation.  Out of the box MVC comes with support for Data Annotations (that is, System.ComponentModel.DataAnnotations) and can be extended to support other frameworks.  Data Annotations Validation is becoming more popular and is being baked in to many other Microsoft offerings, including Entity Framework, though with MVC it only contains four validators: Range, Required, StringLength and Regular Expression.  The Data Annotations Extensions project attempts to augment these validators with additional attributes while maintaining the clean integration Data Annotations provides. A Quick Word About Data Annotations Extensions The Data Annotations Extensions project can be found at http://dataannotationsextensions.org/, and currently provides 11 additional validation attributes (ex: Email, EqualTo, Min/Max) on top of Data Annotations’ original 4.  You can find a current list of the validation attributes on the afore mentioned website. The core library provides server-side validation attributes that can be used in any .NET 4.0 project (no MVC dependency). There is also an easily pluggable client-side validation library which can be used in ASP.NET MVC 3 projects using unobtrusive jquery validation (only MVC3 included javascript files are required). On to the Preview Let’s say you had the following “Customer” domain model (or view model, depending on your project structure) in an MVC 3 project: public class Customer { public string Email { get; set; } public int Age { get; set; } public string ProfilePictureLocation { get; set; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } When it comes time to create/edit this Customer, you will probably have a CustomerController and a simple form that just uses one of the Html.EditorFor() methods that the ASP.NET MVC tooling generates for you (or you can write yourself).  It should look something like this: With no validation, the customer can enter nonsense for an email address, and then can even report their age as a negative number!  With the built-in Data Annotations validation, I could do a bit better by adding a Range to the age, adding a RegularExpression for email (yuck!), and adding some required attributes.  However, I’d still be able to report my age as 10.75 years old, and my profile picture could still be any string.  Let’s use Data Annotations along with this project, Data Annotations Extensions, and see what we can get: public class Customer { [Email] [Required] public string Email { get; set; }   [Integer] [Min(1, ErrorMessage="Unless you are benjamin button you are lying.")] [Required] public int Age { get; set; }   [FileExtensions("png|jpg|jpeg|gif")] public string ProfilePictureLocation { get; set; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now let’s try to put in some invalid values and see what happens: That is very nice validation, all done on the client side (will also be validated on the server).  Also, the Customer class validation attributes are very easy to read and understand. Another bonus: Since Data Annotations Extensions can integrate with MVC 3’s unobtrusive validation, no additional scripts are required! Now that we’ve seen our target, let’s take a look at how to get there within a new MVC 3 project. Adding Data Annotations Extensions To Your Project First we will File->New Project and create an ASP.NET MVC 3 project.  I am going to use Razor for these examples, but any view engine can be used in practice.  Now go into the NuGet Extension Manager (right click on references and select add Library Package Reference) and search for “DataAnnotationsExtensions.”  You should see the following two packages: The first package is for server-side validation scenarios, but since we are using MVC 3 and would like comprehensive sever and client validation support, click on the DataAnnotationsExtensions.MVC3 project and then click Install.  This will install the Data Annotations Extensions server and client validation DLLs along with David Ebbo’s web activator (which enables the validation attributes to be registered with MVC 3). Now that Data Annotations Extensions is installed you have all you need to start doing advanced model validation.  If you are already using Data Annotations in your project, just making use of the additional validation attributes will provide client and server validation automatically.  However, assuming you are starting with a blank project I’ll walk you through setting up a controller and model to test with. Creating Your Model In the Models folder, create a new User.cs file with a User class that you can use as a model.  To start with, I’ll use the following class: public class User { public string Email { get; set; } public string Password { get; set; } public string PasswordConfirm { get; set; } public string HomePage { get; set; } public int Age { get; set; } } Next, create a simple controller with at least a Create method, and then a matching Create view (note, you can do all of this via the MVC built-in tooling).  Your files will look something like this: UserController.cs: public class UserController : Controller { public ActionResult Create() { return View(new User()); }   [HttpPost] public ActionResult Create(User user) { if (!ModelState.IsValid) { return View(user); }   return Content("User valid!"); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Create.cshtml: @model NuGetValidationTester.Models.User   @{ ViewBag.Title = "Create"; }   <h2>Create</h2>   <script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script>   @using (Html.BeginForm()) { @Html.ValidationSummary(true) <fieldset> <legend>User</legend> @Html.EditorForModel() <p> <input type="submit" value="Create" /> </p> </fieldset> } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } In the Create.cshtml view, note that we are referencing jquery validation and jquery unobtrusive (jquery is referenced in the layout page).  These MVC 3 included scripts are the only ones you need to enjoy both the basic Data Annotations validation as well as the validation additions available in Data Annotations Extensions.  These references are added by default when you use the MVC 3 “Add View” dialog on a modification template type. Now when we go to /User/Create we should see a form for editing a User Since we haven’t yet added any validation attributes, this form is valid as shown (including no password, email and an age of 0).  With the built-in Data Annotations attributes we can make some of the fields required, and we could use a range validator of maybe 1 to 110 on Age (of course we don’t want to leave out supercentenarians) but let’s go further and validate our input comprehensively using Data Annotations Extensions.  The new and improved User.cs model class. { [Required] [Email] public string Email { get; set; }   [Required] public string Password { get; set; }   [Required] [EqualTo("Password")] public string PasswordConfirm { get; set; }   [Url] public string HomePage { get; set; }   [Integer] [Min(1)] public int Age { get; set; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now let’s re-run our form and try to use some invalid values: All of the validation errors you see above occurred on the client, without ever even hitting submit.  The validation is also checked on the server, which is a good practice since client validation is easily bypassed. That’s all you need to do to start a new project and include Data Annotations Extensions, and of course you can integrate it into an existing project just as easily. Nitpickers Corner ASP.NET MVC 3 futures defines four new data annotations attributes which this project has as well: CreditCard, Email, Url and EqualTo.  Unfortunately referencing MVC 3 futures necessitates taking an dependency on MVC 3 in your model layer, which may be unadvisable in a multi-tiered project.  Data Annotations Extensions keeps the server and client side libraries separate so using the project’s validation attributes don’t require you to take any additional dependencies in your model layer which still allowing for the rich client validation experience if you are using MVC 3. Custom Error Message and Globalization: Since the Data Annotations Extensions are build on top of Data Annotations, you have the ability to define your own static error messages and even to use resource files for very customizable error messages. Available Validators: Please see the project site at http://dataannotationsextensions.org/ for an up-to-date list of the new validators included in this project.  As of this post, the following validators are available: CreditCard Date Digits Email EqualTo FileExtensions Integer Max Min Numeric Url Conclusion Hopefully I’ve illustrated how easy it is to add server and client validation to your MVC 3 projects, and how to easily you can extend the available validation options to meet real world needs. The Data Annotations Extensions project is fully open source under the BSD license.  Any feedback would be greatly appreciated.  More information than you require, along with links to the source code, is available at http://dataannotationsextensions.org/. Enjoy!

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  • CLSF & CLK 2013 Trip Report by Jeff Liu

    - by jamesmorris
    This is a contributed post from Jeff Liu, lead XFS developer for the Oracle mainline Linux kernel team. Recently, I attended both the China Linux Storage and Filesystem workshop (CLSF), and the China Linux Kernel conference (CLK), which were held in Shanghai. Here are the highlights for both events. CLSF - 17th October XFS update (led by Jeff Liu) XFS keeps rapid progress with a lot of changes, especially focused on the infrastructure/performance improvements as well as  new feature development.  This can be reflected with a sample statistics among XFS/Ext4+JBD2/Btrfs via: # git diff --stat --minimal -C -M v3.7..v3.12-rc4 -- fs/xfs|fs/ext4+fs/jbd2|fs/btrfs XFS: 141 files changed, 27598 insertions(+), 19113 deletions(-) Ext4+JBD2: 39 files changed, 10487 insertions(+), 5454 deletions(-) Btrfs: 70 files changed, 19875 insertions(+), 8130 deletions(-) What made up those changes in XFS? Self-describing metadata(CRC32c). This is a new feature and it contributed about 70% code changes, it can be enabled via `mkfs.xfs -m crc=1 /dev/xxx` for v5 superblock. Transaction log space reservation improvements. With this change, we can calculate the log space reservation at mount time rather than runtime to reduce the the CPU overhead. User namespace support. So both XFS and USERNS can be enabled on kernel configuration begin from Linux 3.10. Thanks Dwight Engen's efforts for this thing. Split project/group quota inodes. Originally, project quota can not be enabled with group quota at the same time because they were share the same quota file inode, now it works but only for v5 super block. i.e, CRC enabled. CONFIG_XFS_WARN, an new lightweight runtime debugger which can be deployed in production environment. Readahead log object recovery, this change can speed up the log replay progress significantly. Speculative preallocation inode tracking, clearing and throttling. The main purpose is to deal with inodes with post-EOF space due to speculative preallocation, support improved quota management to free up a significant amount of unwritten space when at or near EDQUOT. It support backgroup scanning which occurs on a longish interval(5 mins by default, tunable), and on-demand scanning/trimming via ioctl(2). Bitter arguments ensued from this session, especially for the comparison between Ext4 and Btrfs in different areas, I have to spent a whole morning of the 1st day answering those questions. We basically agreed on XFS is the best choice in Linux nowadays because: Stable, XFS has a good record in stability in the past 10 years. Fengguang Wu who lead the 0-day kernel test project also said that he has observed less error than other filesystems in the past 1+ years, I own it to the XFS upstream code reviewer, they always performing serious code review as well as testing. Good performance for large/small files, XFS does not works very well for small files has already been an old story for years. Best choice (maybe) for distributed PB filesystems. e.g, Ceph recommends delopy OSD daemon on XFS because Ext4 has limited xattr size. Best choice for large storage (>16TB). Ext4 does not support a single file more than around 15.95TB. Scalability, any objection to XFS is best in this point? :) XFS is better to deal with transaction concurrency than Ext4, why? The maximum size of the log in XFS is 2038MB compare to 128MB in Ext4. Misc. Ext4 is widely used and it has been proved fast/stable in various loads and scenarios, XFS just need more customers, and Btrfs is still on the road to be a manhood. Ceph Introduction (Led by Li Wang) This a hot topic.  Li gave us a nice introduction about the design as well as their current works. Actually, Ceph client has been included in Linux kernel since 2.6.34 and supported by Openstack since Folsom but it seems that it has not yet been widely deployment in production environment. Their major work is focus on the inline data support to separate the metadata and data storage, reduce the file access time, i.e, a file access need communication twice, fetch the metadata from MDS and then get data from OSD, and also, the small file access is limited by the network latency. The solution is, for the small files they would like to store the data at metadata so that when accessing a small file, the metadata server can push both metadata and data to the client at the same time. In this way, they can reduce the overhead of calculating the data offset and save the communication to OSD. For this feature, they have only run some small scale testing but really saw noticeable improvements. Test environment: Intel 2 CPU 12 Core, 64GB RAM, Ubuntu 12.04, Ceph 0.56.6 with 200GB SATA disk, 15 OSD, 1 MDS, 1 MON. The sequence read performance for 1K size files improved about 50%. I have asked Li and Zheng Yan (the core developer of Ceph, who also worked on Btrfs) whether Ceph is really stable and can be deployed at production environment for large scale PB level storage, but they can not give a positive answer, looks Ceph even does not spread over Dreamhost (subject to confirmation). From Li, they only deployed Ceph for a small scale storage(32 nodes) although they'd like to try 6000 nodes in the future. Improve Linux swap for Flash storage (led by Shaohua Li) Because of high density, low power and low price, flash storage (SSD) is a good candidate to partially replace DRAM. A quick answer for this is using SSD as swap. But Linux swap is designed for slow hard disk storage, so there are a lot of challenges to efficiently use SSD for swap. SWAPOUT swap_map scan swap_map is the in-memory data structure to track swap disk usage, but it is a slow linear scan. It will become a bottleneck while finding many adjacent pages in the use of SSD. Shaohua Li have changed it to a cluster(128K) list, resulting in O(1) algorithm. However, this apporoach needs restrictive cluster alignment and only enabled for SSD. IO pattern In most cases, the swap io is in interleaved pattern because of mutiple reclaimers or a free cluster is shared by all reclaimers. Even though block layer can merge interleaved IO to some extent, but we cannot count on it completely. Hence the per-cpu cluster is added base on the previous change, it can help reclaimer do sequential IO and the block layer will be easier to merge IO. TLB flush: If we're reclaiming one active page, we should first move the page from active lru list to inactive lru list, and then reclaim the page from inactive lru to swap it out. During the process, we need to clear PTE twice: first is 'A'(ACCESS) bit, second is 'P'(PRESENT) bit. Processors need to send lots of ipi which make the TLB flush really expensive. Some works have been done to improve this, including rework smp_call_functiom_many() or remove the first TLB flush in x86, but there still have some arguments here and only parts of works have been pushed to mainline. SWAPIN: Page fault does iodepth=1 sync io, but it's a little waste if only issue a page size's IO. The obvious solution is doing swap readahead. But the current in-kernel swap readahead is arbitary(always 8 pages), and it always doesn't perform well for both random and sequential access workload. Shaohua introduced a new flag for madvise(MADV_WILLNEED) to do swap prefetch, so the changes happen in userspace API and leave the in-kernel readahead unchanged(but I think some improvement can also be done here). SWAP discard As we know, discard is important for SSD write throughout, but the current swap discard implementation is synchronous. He changed it to async discard which allow discard and write run in the same time. Meanwhile, the unit of discard is also optimized to cluster. Misc: lock contention For many concurrent swapout and swapin , the lock contention such as anon_vma or swap_lock is high, so he changed the swap_lock to a per-swap lock. But there still have some lock contention in very high speed SSD because of swapcache address_space lock. Zproject (led by Bob Liu) Bob gave us a very nice introduction about the current memory compression status. Now there are 3 projects(zswap/zram/zcache) which all aim at smooth swap IO storm and promote performance, but they all have their own pros and cons. ZSWAP It is implemented based on frontswap API and it uses a dynamic allocater named Zbud to allocate free pages. Zbud means pairs of zpages are "buddied" and it can only store at most two compressed pages in one page frame, so the max compress ratio is 50%. Each page frame is lru-linked and can do shink in memory pressure. If the compressed memory pool reach its limitation, shink or reclaim happens. It decompress the page frame into two new allocated pages and then write them to real swap device, but it can fail when allocating the two pages. ZRAM Acts as a compressed ramdisk and used as swap device, and it use zsmalloc as its allocator which has high density but may have fragmentation issues. Besides, page reclaim is hard since it will need more pages to uncompress and free just one page. ZRAM is preferred by embedded system which may not have any real swap device. Now both ZRAM and ZSWAP are in driver/staging tree, and in the mm community there are some disscussions of merging ZRAM into ZSWAP or viceversa, but no agreement yet. ZCACHE Handles file page compression but it is removed out of staging recently. From industry (led by Tang Jie, LSI) An LSI engineer introduced several new produces to us. The first is raid5/6 cards that it use full stripe writes to improve performance. The 2nd one he introduced is SandForce flash controller, who can understand data file types (data entropy) to reduce write amplification (WA) for nearly all writes. It's called DuraWrite and typical WA is 0.5. What's more, if enable its Dynamic Logical Capacity function module, the controller can do data compression which is transparent to upper layer. LSI testing shows that with this virtual capacity enables 1x TB drive can support up to 2x TB capacity, but the application must monitor free flash space to maintain optimal performance and to guard against free flash space exhaustion. He said the most useful application is for datebase. Another thing I think it's worth to mention is that a NV-DRAM memory in NMR/Raptor which is directly exposed to host system. Applications can directly access the NV-DRAM via a memory address - using standard system call mmap(). He said that it is very useful for database logging now. This kind of NVM produces are beginning to appear in recent years, and it is said that Samsung is building a research center in China for related produces. IMHO, NVM will bring an effect to current os layer especially on file system, e.g. its journaling may need to redesign to fully utilize these nonvolatile memory. OCFS2 (led by Canquan Shen) Without a doubt, HuaWei is the biggest contributor to OCFS2 in the past two years. They have posted 46 upstream patches and 39 patches have been merged. Their current project is based on 32/64 nodes cluster, but they also tried 128 nodes at the experimental stage. The major work they are working is to support ATS (atomic test and set), it can be works with DLM at the same time. Looks this idea is inspired by the vmware VMFS locking, i.e, http://blogs.vmware.com/vsphere/2012/05/vmfs-locking-uncovered.html CLK - 18th October 2013 Improving Linux Development with Better Tools (Andi Kleen) This talk focused on how to find/solve bugs along with the Linux complexity growing. Generally, we can do this with the following kind of tools: Static code checkers tools. e.g, sparse, smatch, coccinelle, clang checker, checkpatch, gcc -W/LTO, stanse. This can help check a lot of things, simple mistakes, complex problems, but the challenges are: some are very slow, false positives, may need a concentrated effort to get false positives down. Especially, no static checker I found can follow indirect calls (“OO in C”, common in kernel): struct foo_ops { int (*do_foo)(struct foo *obj); } foo->do_foo(foo); Dynamic runtime checkers, e.g, thread checkers, kmemcheck, lockdep. Ideally all kernel code would come with a test suite, then someone could run all the dynamic checkers. Fuzzers/test suites. e.g, Trinity is a great tool, it finds many bugs, but needs manual model for each syscall. Modern fuzzers around using automatic feedback, but notfor kernel yet: http://taviso.decsystem.org/making_software_dumber.pdf Debuggers/Tracers to understand code, e.g, ftrace, can dump on events/oops/custom triggers, but still too much overhead in many cases to run always during debug. Tools to read/understand source, e.g, grep/cscope work great for many cases, but do not understand indirect pointers (OO in C model used in kernel), give us all “do_foo” instances: struct foo_ops { int (*do_foo)(struct foo *obj); } = { .do_foo = my_foo }; foo>do_foo(foo); That would be great to have a cscope like tool that understands this based on types/initializers XFS: The High Performance Enterprise File System (Jeff Liu) [slides] I gave a talk for introducing the disk layout, unique features, as well as the recent changes.   The slides include some charts to reflect the performances between XFS/Btrfs/Ext4 for small files. About a dozen users raised their hands when I asking who has experienced with XFS. I remembered that when I asked the same question in LinuxCon/Japan, only 3 people raised their hands, but they are Chris Mason, Ric Wheeler, and another attendee. The attendee questions were mainly focused on stability, and comparison with other file systems. Linux Containers (Feng Gao) The speaker introduced us that the purpose for those kind of namespaces, include mount/UTS/IPC/Network/Pid/User, as well as the system API/ABI. For the userspace tools, He mainly focus on the Libvirt LXC rather than us(LXC). Libvirt LXC is another userspace container management tool, implemented as one type of libvirt driver, it can manage containers, create namespace, create private filesystem layout for container, Create devices for container and setup resources controller via cgroup. In this talk, Feng also mentioned another two possible new namespaces in the future, the 1st is the audit, but not sure if it should be assigned to user namespace or not. Another is about syslog, but the question is do we really need it? In-memory Compression (Bob Liu) Same as CLSF, a nice introduction that I have already mentioned above. Misc There were some other talks related to ACPI based memory hotplug, smart wake-affinity in scheduler etc., but my head is not big enough to record all those things. -- Jeff Liu

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  • Log message Request and Response in ASP.NET WebAPI

    - by Fredrik N
    By logging both incoming and outgoing messages for services can be useful in many scenarios, such as debugging, tracing, inspection and helping customers with request problems etc.  I have a customer that need to have both incoming and outgoing messages to be logged. They use the information to see strange behaviors and also to help customers when they call in  for help (They can by looking in the log see if the customers sends in data in a wrong or strange way).   Concerns Most loggings in applications are cross-cutting concerns and should not be  a core concern for developers. Logging messages like this:   // GET api/values/5 public string Get(int id) { //Cross-cutting concerns Log(string.Format("Request: GET api/values/{0}", id)); //Core-concern var response = DoSomething(); //Cross-cutting concerns Log(string.Format("Reponse: GET api/values/{0}\r\n{1}", id, response)); return response; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } will only result in duplication of code, and unnecessarily concerns for the developers to be aware of, if they miss adding the logging code, no logging will take place. Developers should focus on the core-concern, not the cross-cutting concerns. By just focus on the core-concern the above code will look like this: // GET api/values/5 public string Get(int id) { return DoSomething(); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The logging should then be placed somewhere else so the developers doesn’t need to focus care about the cross-concern. Using Message Handler for logging There are different ways we could place the cross-cutting concern of logging message when using WebAPI. We can for example create a custom ApiController and override the ApiController’s ExecutingAsync method, or add a ActionFilter, or use a Message Handler. The disadvantage with custom ApiController is that we need to make sure we inherit from it, the disadvantage of ActionFilter, is that we need to add the filter to the controllers, both will modify our ApiControllers. By using a Message Handler we don’t need to do any changes to our ApiControllers. So the best suitable place to add our logging would be in a custom Message Handler. A Message Handler will be used before the HttpControllerDispatcher (The part in the WepAPI pipe-line that make sure the right controller is used and called etc). Note: You can read more about message handlers here, it will give you a good understanding of the WebApi pipe-line. To create a Message Handle we can inherit from the DelegatingHandler class and override the SendAsync method: public class MessageHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { return base.SendAsync(request, cancellationToken); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   If we skip the call to the base.SendAsync our ApiController’s methods will never be invoked, nor other Message Handlers. Everything placed before base.SendAsync will be called before the HttpControllerDispatcher (before WebAPI will take a look at the request which controller and method it should be invoke), everything after the base.SendAsync, will be executed after our ApiController method has returned a response. So a message handle will be a perfect place to add cross-cutting concerns such as logging. To get the content of our response within a Message Handler we can use the request argument of the SendAsync method. The request argument is of type HttpRequestMessage and has a Content property (Content is of type HttpContent. The HttpContent has several method that can be used to read the incoming message, such as ReadAsStreamAsync, ReadAsByteArrayAsync and ReadAsStringAsync etc. Something to be aware of is what will happen when we read from the HttpContent. When we read from the HttpContent, we read from a stream, once we read from it, we can’t be read from it again. So if we read from the Stream before the base.SendAsync, the next coming Message Handlers and the HttpControllerDispatcher can’t read from the Stream because it’s already read, so our ApiControllers methods will never be invoked etc. The only way to make sure we can do repeatable reads from the HttpContent is to copy the content into a buffer, and then read from that buffer. This can be done by using the HttpContent’s LoadIntoBufferAsync method. If we make a call to the LoadIntoBufferAsync method before the base.SendAsync, the incoming stream will be read in to a byte array, and then other HttpContent read operations will read from that buffer if it’s exists instead directly form the stream. There is one method on the HttpContent that will internally make a call to the  LoadIntoBufferAsync for us, and that is the ReadAsByteArrayAsync. This is the method we will use to read from the incoming and outgoing message. public abstract class MessageHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { var requestMessage = await request.Content.ReadAsByteArrayAsync(); var response = await base.SendAsync(request, cancellationToken); var responseMessage = await response.Content.ReadAsByteArrayAsync(); return response; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The above code will read the content of the incoming message and then call the SendAsync and after that read from the content of the response message. The following code will add more logic such as creating a correlation id to combine the request with the response, and create a log entry etc: public abstract class MessageHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { var corrId = string.Format("{0}{1}", DateTime.Now.Ticks, Thread.CurrentThread.ManagedThreadId); var requestInfo = string.Format("{0} {1}", request.Method, request.RequestUri); var requestMessage = await request.Content.ReadAsByteArrayAsync(); await IncommingMessageAsync(corrId, requestInfo, requestMessage); var response = await base.SendAsync(request, cancellationToken); var responseMessage = await response.Content.ReadAsByteArrayAsync(); await OutgoingMessageAsync(corrId, requestInfo, responseMessage); return response; } protected abstract Task IncommingMessageAsync(string correlationId, string requestInfo, byte[] message); protected abstract Task OutgoingMessageAsync(string correlationId, string requestInfo, byte[] message); } public class MessageLoggingHandler : MessageHandler { protected override async Task IncommingMessageAsync(string correlationId, string requestInfo, byte[] message) { await Task.Run(() => Debug.WriteLine(string.Format("{0} - Request: {1}\r\n{2}", correlationId, requestInfo, Encoding.UTF8.GetString(message)))); } protected override async Task OutgoingMessageAsync(string correlationId, string requestInfo, byte[] message) { await Task.Run(() => Debug.WriteLine(string.Format("{0} - Response: {1}\r\n{2}", correlationId, requestInfo, Encoding.UTF8.GetString(message)))); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The code above will show the following in the Visual Studio output window when the “api/values” service (One standard controller added by the default WepAPI template) is requested with a Get http method : 6347483479959544375 - Request: GET http://localhost:3208/api/values 6347483479959544375 - Response: GET http://localhost:3208/api/values ["value1","value2"] .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Register a Message Handler To register a Message handler we can use the Add method of the GlobalConfiguration.Configration.MessageHandlers in for example Global.asax: public class WebApiApplication : System.Web.HttpApplication { protected void Application_Start() { GlobalConfiguration.Configuration.MessageHandlers.Add(new MessageLoggingHandler()); ... } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Summary By using a Message Handler we can easily remove cross-cutting concerns like logging from our controllers. You can also find the source code used in this blog post on ForkCan.com, feel free to make a fork or add comments, such as making the code better etc. Feel free to follow me on twitter @fredrikn if you want to know when I will write other blog posts etc.

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