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• MSSQL: Copying data from one database to another

  - by DigiMortal

  I have database that has data imported from another server using import and export wizard of SQL Server Management Studio. There is also empty database with same tables but it also has primary keys, foreign keys and indexes. How to get data from first database to another? Here is the description of my crusade. And believe me – it is not nice one. Bugs in import and export wizard There is some awful bugs in import and export wizard that makes data imports and exports possible only on very limited manner: wizard is not able to analyze foreign keys, wizard wants to create tables always, whatever you say in settings. The result is faulty and useless package. Now let’s go step by step and make things work in our scenario. Database There are two databases. Let’s name them like this: PLAIN – contains data imported from remote server (no indexes, no keys, no nothing, just plain dumb data) CORRECT – empty database with same structure as remote database (indexes, keys and everything else but no data) Our goal is to get data from PLAIN to CORRECT. 1. Create import and export package In this point we will create faulty SSIS package using SQL Server Management Studio. Run import and export wizard and let it create SSIS package that reads data from CORRECT and writes it to, let’s say, CORRECT-2. Make sure you enable identity insert. Make sure there are no views selected. Make sure you don’t let package to create tables (you can miss this step because it wants to create tables anyway). Save package to SSIS. 2. Modify import and export package Now let’s clean up the package and remove all faulty crap. Connect SQL Server Management Studio to SSIS instance. Select the package you just saved and export it to your hard disc. Run Business Intelligence Studio. Create new SSIS project (DON’T MISS THIS STEP). Add package from disc as existing item to project and open it. Move to Control Flow page do one of following: Remove all preparation SQL-tasks and connect Data Flow tasks. Modify all preparation SQL-tasks so the existence of tables is checked before table is created (yes, you have to do it manually). Add new Execute-SQL task as first task in control flow: Open task properties. Assign destination connection as connection to use. Insert the following SQL as command:   EXEC sp_MSForEachTable 'ALTER TABLE ? NOCHECK CONSTRAINT ALL' GO   EXEC sp_MSForEachTable 'DELETE FROM ?' GO   Save task. Add new Execute-SQL task as last task in control flow: Open task properties. Assign destination connection as connection to use. Insert the following SQL as command:   EXEC sp_MSForEachTable 'ALTER TABLE ? CHECK CONSTRAINT ALL' GO   Save task Now connect first Execute-SQL task with first Data Flow task and last Data Flow task with second Execute-SQL task. Now move to Package Explorer tab and change connections under Connection Managers folder. Make source connection to use database PLAIN. Make destination connection to use database CORRECT. Save package and rebuilt the project. Update package using SQL Server Management Studio. Some hints: Make sure you take the package from solution folder because it is saved there now. Don’t overwrite existing package. Use numeric suffix and let Management Studio to create a new version of package. Now you are done with your package. Run it to test it and clean out all the errors you find. TRUNCATE vs DELETE You can see that I used DELETE FROM instead of TRUNCATE. Why? Because TRUNCATE has some nasty limits (taken from MSDN): “You cannot use TRUNCATE TABLE on a table referenced by a FOREIGN KEY constraint; instead, use DELETE statement without a WHERE clause. Because TRUNCATE TABLE is not logged, it cannot activate a trigger. TRUNCATE TABLE may not be used on tables participating in an indexed view.” As I am not sure what tables you have and how they are used I provided here the solution that should work for all scenarios. If you need better performance then in some cases you can use TRUNCATE table instead of DELETE. Conclusion My conclusion is bitter this time although I am very positive guy. It is A.D. 2010 and still we have to write stupid hacks for simple things. Simple tools that existed before are long gone and we have to live mysterious bloatware that is our only choice when using default tools. If you take a look at the length of this posting and the count of steps I had to do for one easy thing you should treat it as a signal that something has went wrong in last years. Although I got my job done I would be still more happy if out of box tools are more intelligent one day. References T-SQL Trick for Deleting All Data in Your Database (Mauro Cardarelli) TRUNCATE TABLE (MSDN Library) Error Handling in SQL 2000 – a Background (Erland Sommarskog) Disable/Enable Foreign Key and Check constraints in SQL Server (Decipher)

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• ASP.NET: Using conditionals in data binding expressions

  - by DigiMortal

  ASP.NET 2.0 has no support for using conditionals in data binding expressions but it will change in ASP.NET 4.0. In this posting I will show you how to implement Iif() function for ASP.NET 2.0 and how ASP.NET 4.0 solves this problem smoothly without any code. Problem Let’s say we have simple repeater. <asp:Repeater runat="server" ID="itemsList">     <HeaderTemplate>         <table border="1" cellspacing="0" cellpadding="5">     </HeaderTemplate>     <ItemTemplate>         <tr>         <td align="right"><%# Container.ItemIndex + 1 %>.</td>         <td><%# Eval("Title") %></td>         </tr>     </ItemTemplate>     <FooterTemplate>         </table>     </FooterTemplate> </asp:Repeater> Repeater is bound to data when form loads. protected void Page_Load(object sender, EventArgs e) {     var items = new[] {                     new { Id = 1, Title = "Headline 1" },                     new { Id = 2, Title = "Headline 2" },                     new { Id = 2, Title = "Headline 3" },                     new { Id = 2, Title = "Headline 4" },                     new { Id = 2, Title = "Headline 5" }                 };     itemsList.DataSource = items;     itemsList.DataBind(); } We need to format even and odd rows differently. Let’s say we want even rows to be with whitesmoke background and odd rows with white background. Just like shown on screenshot on right. Our first thought is to use some simple expression to avoid writing custom methods. We cannot use construct like this <%# Container.ItemIndex % 2==0 ? "white" : "whitesmoke"  %> because all we get are template compilation errors. ASP.NET 2.0: Iif() method For ASP.NET 2.0 pages and controls we can create Iif() method and call it from our templates. This is out Iif() method. protected object Iif(bool condition, object trueResult, object falseResult) {     return condition ? trueResult : falseResult; } And here you can see how to use it. <asp:Repeater runat="server" ID="itemsList">   <HeaderTemplate>     <table border="1" cellspacing="0" cellpadding="5">     </HeaderTemplate>   <ItemTemplate>     <tr style='background-color:'       <%# Iif(Container.ItemIndex % 2==0 ? "white" : "whitesmoke") %>'>       <td align="right">         <%# Container.ItemIndex + 1 %>.</td>       <td>         <%# Eval("Title") %></td>     </tr>   </ItemTemplate>   <FooterTemplate>     </table>   </FooterTemplate> </asp:Repeater> This method does not care about types because it works with all objects (and value-types). I had to define this method in code-behind file of my user control because using this method as extension method made it undetectable for ASP.NET template engine. ASP.NET 4.0: Conditionals are supported In ASP.NET 4.0 we will write … hmm … we will write nothing special. Here is solution. <asp:Repeater runat="server" ID="itemsList">   <HeaderTemplate>     <table border="1" cellspacing="0" cellpadding="5">     </HeaderTemplate>   <ItemTemplate>     <tr style='background-color:'       <%# Container.ItemIndex % 2==0 ? "white" : "whitesmoke" %>'>       <td align="right">         <%# Container.ItemIndex + 1 %>.</td>       <td>         <%# Eval("Title") %></td>     </tr>   </ItemTemplate>   <FooterTemplate>     </table>   </FooterTemplate> </asp:Repeater> Yes, it works well. :)

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• 5 minutes WIF: Make your ASP.NET application use test-STS

  - by DigiMortal

  Windows Identity Foundation (WIF) provides us with simple and dummy STS application we can use to develop our system with no actual STS in place. In this posting I will show you how to add STS support to your existing application and how to generate dummy application that plays you real STS. Word of caution! Although it is relatively easy to build your own STS using WIF tools I don’t recommend you to build it. Identity providers must be highly secure and stable in every means and this makes development of your own STS very complex task. If it is possible then use some known STS solution. I suppose you have WIF and WIF SDK installed on your development machine. If you don’t then here are the links to download pages: Windows Identity Foundation Windows Identity Foundation SDK Adding STS support to your web application Suppose you have web application and you want to externalize authentication so your application is able to detect users, send unauthenticated users to login and work in other terms exactly like it worked before. WIF tools provide you with all you need. 1. Click on your web application project and select “Add STS reference…” from context menu to start adding or updating STS settings for web application. 2. Insert your application URI in application settings window. Note that web.config file is already selected for you. I inserted URI that corresponds to my web application address under IIS Express. This URI must exist (later) because otherwise you cannot use dummy STS service. 3. Select “Create a new STS project in the current solution” and click Next button. 4. Summary screen gives you information about how your site will use STS. You can run this wizard always when you have to modify STS parameters. Click Finish. If everything goes like expected then new web site will be added to your solution and it is named as YourWebAppName_STS. Dummy STS application Image on right shows you dummy STS web site. Yes, it is created as web site project not as web application. But it still works nice and you don’t have to make there any modifications. It just works but it is dummy one. Why dummy STS? Some points about dummy STS web site: Dummy STS is not template for your own custom STS identity provider. Dummy STS is very good and simple replacement of real STS so you have more flexible development environment and you don’t have to authenticate yourself in real service. Of course, you can modify dummy STS web site to mimic some behavior of your real STS. Pages in dummy STS Dummy STS has two pages – Login.aspx and  Default.aspx. Default.aspx is the page that handles requests to STS service. Login.aspx is the page where authentication takes place. Dummy STS authenticates users using FBA. You can insert whatever username you like and dummy STS still works. You can take a look at the code behind these pages to get some idea about how this dummy service is built up. But again – this service is there to simplify your life as developer. Authenticating users using dummy STS If you are using development web server that ships with Visual Studio 2010 I suggest you to switch over to IIS or IIS Express and make some more configuration changes as described in my previous posting Making WIF local STS to work with your ASP.NET application. When you are done with these little modifications you are ready to run your application and see how authentication works. If everything is okay then you are redirected to dummy STS login page when running your web application. Adam Carter is provided as username by default. If you click on submit button you are authenticated and redirected to application page. In my case it looks like this. Conclusion As you saw it is very easy to set up your own dummy STS web site for testing purposes. You coded nothing. You just ran wizard, inserted some data, modified configuration a little bit and you were done. Later, when your application goes to production you can run again this STS configuration utility and it generates correct settings for your real STS service automatically.

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• ASP.NET MVC: Moving code from controller action to service layer

  - by DigiMortal

  I fixed one controller action in my application that doesn’t seemed good enough for me. It wasn’t big move I did but worth to show to beginners how nice code you can write when using correct layering in your application. As an example I use code from my posting ASP.NET MVC: How to implement invitation codes support. Problematic controller action Although my controller action works well I don’t like how it looks. It is too much for controller action in my opinion. [HttpPost] public ActionResult GetAccess(string accessCode) {     if(string.IsNullOrEmpty(accessCode.Trim()))     {         ModelState.AddModelError("accessCode", "Insert invitation code!");         return View();     }       Guid accessGuid;       try     {         accessGuid = Guid.Parse(accessCode);     }     catch     {         ModelState.AddModelError("accessCode", "Incorrect format of invitation code!");         return View();                    }       using(var ctx = new EventsEntities())     {         var user = ctx.GetNewUserByAccessCode(accessGuid);         if(user == null)         {             ModelState.AddModelError("accessCode", "Cannot find account with given invitation code!");             return View();         }           user.UserToken = User.Identity.GetUserToken();         ctx.SaveChanges();     }       Session["UserId"] = accessGuid;       return Redirect("~/admin"); } Looking at this code my first idea is that all this access code stuff must be located somewhere else. We have working functionality in wrong place and we should do something about it. Service layer I add layers to my application very carefully because I don’t like to use hand grenade to kill a fly. When I see real need for some layer and it doesn’t add too much complexity I will add new layer. Right now it is good time to add service layer to my small application. After that it is time to move code to service layer and inject service class to controller. public interface IUserService {     bool ClaimAccessCode(string accessCode, string userToken,                          out string errorMessage);       // Other methods of user service } I need this interface when writing unit tests because I need fake service that doesn’t communicate with database and other external sources. public class UserService : IUserService {     private readonly IDataContext _context;       public UserService(IDataContext context)     {         _context = context;     }       public bool ClaimAccessCode(string accessCode, string userToken, out string errorMessage)     {         if (string.IsNullOrEmpty(accessCode.Trim()))         {             errorMessage = "Insert invitation code!";             return false;         }           Guid accessGuid;         if (!Guid.TryParse(accessCode, out accessGuid))         {             errorMessage = "Incorrect format of invitation code!";             return false;         }           var user = _context.GetNewUserByAccessCode(accessGuid);         if (user == null)         {             errorMessage = "Cannot find account with given invitation code!";             return false;         }           user.UserToken = userToken;         _context.SaveChanges();           errorMessage = string.Empty;         return true;     } } Right now I used simple solution for errors and made access code claiming method to follow usual TrySomething() methods pattern. This way I can keep error messages and their retrieval away from controller and in controller I just mediate error message from service to view. Controller Now all the code is moved to service layer and we need also some modifications to controller code so it makes use of users service. I don’t show here DI/IoC details about how to give service instance to controller. GetAccess() action of controller looks like this right now. [HttpPost] public ActionResult GetAccess(string accessCode) {     var userToken = User.Identity.GetUserToken();     string errorMessage;       if (!_userService.ClaimAccessCode(accessCode, userToken,                                       out errorMessage))     {                       ModelState.AddModelError("accessCode", errorMessage);         return View();     }       Session["UserId"] = Guid.Parse(accessCode);     return Redirect("~/admin"); } It’s short and nice now and it deals with web site part of access code claiming. In the case of error user is shown access code claiming view with error message that ClaimAccessCode() method returns as output parameter. If everything goes fine then access code is reserved for current user and user is authenticated. Conclusion When controller action grows big you have to move code to layers it actually belongs. In this posting I showed you how I moved access code claiming functionality from controller action to user service class that belongs to service layer of my application. As the result I have controller action that coordinates the user interaction when going through access code claiming process. Controller communicates with service layer and gets information about how access code claiming succeeded.

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• Who is code wanderer?

  - by DigiMortal

  In every area of life there are people with some bad habits or misbehaviors that affect the work process. Software development is also not free of this kind of people. Today I will introduce you code wanderer. Who is code wanderer? Code wandering is more like bad habit than serious diagnose. Code wanderers tend to review and “fix” source code in files written by others. When code wanderer has some free moments he starts to open the code files he or she has never seen before and starts making little fixes to these files. Why is code wanderer dangerous? These fixes seem correct and are usually first choice to do when considering nice code. But as changes are made by coder who has no idea about the code he or she “fixes” then “fixing” usually ends up with messing up working code written by others. Often these “fixes” are not found immediately because they doesn’t introduce errors detected by compilers. So these “fixes” find easily way to production environments because there is also very good chance that “fixed” code goes through all tests without any problems. How to stop code wanderer? The first thing is to talk with person and explain him or her why those changes are dangerous. It is also good to establish rules that state clearly why, when and how can somebody change the code written by other people. If this does not work it is possible to isolate this person so he or she can post his or her changes to code repository as patches and somebody reviews those changes before applying them.

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• Code Contracts: validating arrays and collections

  - by DigiMortal

  Validating collections before using them is very common task when we use built-in generic types for our collections. In this posting I will show you how to validate collections using code contracts. It is cool how much awful looking code you can avoid using code contracts. Failing code Let’s suppose we have method that calculates sum of all invoices in collection. We have class Invoice and one of properties it has is Sum. I don’t introduce here any complex calculations on invoices because we have another problem to solve in this topic. Here is our code. public static decimal CalculateTotal(IList<Invoice> invoices) {     var sum = invoices.Sum(p => p.Sum);     return sum; } This method is very simple but it fails when invoices list contains at least one null. Of course, we can test if invoice is null but having nulls in lists like this is not good idea – it opens green way for different coding bugs in system. Our goal is to react to bugs ASAP at the nearest place they occur. There is one more way how to make our method fail. It happens when invoices is null. I thing it is also one common bugs during development and it even happens in production environments under some conditions that are usually hardly met. Now let’s protect our little calculation method with code contracts. We need two contracts: invoices cannot be null invoices cannot contain any nulls Our first contract is easy but how to write the second one? Solution: Contract.ForAll Preconditions in code are checked using Contract.Ensures method. This method takes boolean value as argument that sais if contract holds or not. There is also method Contract.ForAll that takes collection and predicate that must hold for that collection. Nice thing is ForAll returns boolean. So, we have very simple solution. public static decimal CalculateTotal(IList<Invoice> invoices) {     Contract.Requires(invoices != null);     Contract.Requires(Contract.ForAll<Invoice>(invoices, p => p != null));       var sum = invoices.Sum(p => p.Sum);     return sum; } And here are some lines of code you can use to test the contracts quickly. var invoices = new List<Invoice>(); invoices.Add(new Invoice()); invoices.Add(null); invoices.Add(new Invoice()); //CalculateTotal(null); CalculateTotal(invoices); If your code is covered with unit tests then I suggest you to write tests to check that these contracts hold for every code run. Conclusion Although it seemed at first place that checking all elements in collection may end up with for-loops that does not look so nice we were able to solve our problem nicely. ForAll method of contract class offered us simple mechanism to check collections and it does it smoothly the code-contracts-way. P.S. I suggest you also read devlicio.us blog posting Validating Collections with Code Contracts by Derik Whittaker.

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• Using Sandcastle to build code contracts documentation

  - by DigiMortal

  In my last posting about code contracts I showed how code contracts are documented in XML-documents. In this posting I will show you how to get code contracts documented with Sandcastle and Sandcastle Help File Builder. Before we start, let’s download Sandcastle tools we need: Sandcastle Sandcastle Help File Builder Install Sandcastle first and then Sandcastle Help File Builder. Because we are generating only HTML based documentation we upload to server we don’t need any other tools. Of course, we need Cassini or IIS, but I expect it to be already there in your machine. Open your project and turn on XML-documentation for project and contracts. Now let’s run Sandcastle Help File Builder. We have to create new project and add our Visual Studio solution to this project. Now set the HelpFileFormat parameter value to be Website and let builder build the help. You have to wait about two or three minutes until help is ready. Take a look at your documentation that Sandcastle generated – you see not much information there about code contracts and their rules. Enabling code contracts documentation Now let’s include code contracts to documentation. Follow these steps: Open Sandcastle folder and make copy of vs2005 folder. Open CodeContracts folder (c:\program files\microsoft\contracts\) and unzip the archive from sandcastle folder. Copy all unzipped files to Sandcastle folder. Create (yes, create new) and build your Sandcastle Help File Builder documentation project again. Open help. In my case I see something like this now. As you can see then contracts are documented pretty well. We can easily turn on code contracts XML-documentation generation and all our contracts are documented automatically. To get documentation work we had to use Sandcastle help file fixes that are installed with code contracts and if we had previously Sandcastle Help File Builder project we had to create it from start to get new rules accepted. Once the documentation support for contracts works we have to do nothing more to get contracts documented.

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• ASP.NET MVC: Using ProfileRequiredAttribute to restrict access to pages

  - by DigiMortal

  If you are using AppFabric Access Control Services to authenticate users when they log in to your community site using Live ID, Google or some other popular identity provider, you need more than AuthorizeAttribute to make sure that users can access the content that is there for authenticated users only. In this posting I will show you hot to extend the AuthorizeAttribute so users must also have user profile filled. Semi-authorized users When user is authenticated through external identity provider then not all identity providers give us user name or other information we ask users when they join with our site. What all identity providers have in common is unique ID that helps you identify the user. Example. Users authenticated through Windows Live ID by AppFabric ACS have no name specified. Google’s identity provider is able to provide you with user name and e-mail address if user agrees to publish this information to you. They both give you unique ID of user when user is successfully authenticated in their service. There is logical shift between ASP.NET and my site when considering user as authorized. For ASP.NET MVC user is authorized when user has identity. For my site user is authorized when user has profile and row in my users table. Having profile means that user has unique username in my system and he or she is always identified by this username by other users. My solution is simple: I created my own action filter attribute that makes sure if user has profile to access given method and if user has no profile then browser is redirected to join page. Illustrating the problem Usually we restrict access to page using AuthorizeAttribute. Code is something like this. [Authorize] public ActionResult Details(string id) {     var profile = _userRepository.GetUserByUserName(id);     return View(profile); } If this page is only for site users and we have user profiles then all users – the ones that have profile and all the others that are just authenticated – can access the information. It is okay because all these users have successfully logged in in some service that is supported by AppFabric ACS. In my site the users with no profile are in grey spot. They are on half way to be users because they have no username and profile on my site yet. So looking at the image above again we need something that adds profile existence condition to user-only content. [ProfileRequired] public ActionResult Details(string id) {     var profile = _userRepository.GetUserByUserName(id);     return View(profile); } Now, this attribute will solve our problem as soon as we implement it. ProfileRequiredAttribute: Profiles are required to be fully authorized Here is my implementation of ProfileRequiredAttribute. It is pretty new and right now it is more like working draft but you can already play with it. public class ProfileRequiredAttribute : AuthorizeAttribute {     private readonly string _redirectUrl;       public ProfileRequiredAttribute()     {         _redirectUrl = ConfigurationManager.AppSettings["JoinUrl"];         if (string.IsNullOrWhiteSpace(_redirectUrl))             _redirectUrl = "~/";     }              public override void OnAuthorization(AuthorizationContext filterContext)     {         base.OnAuthorization(filterContext);           var httpContext = filterContext.HttpContext;         var identity = httpContext.User.Identity;           if (!identity.IsAuthenticated || identity.GetProfile() == null)             if(filterContext.Result == null)                 httpContext.Response.Redirect(_redirectUrl);          } } All methods with this attribute work as follows: if user is not authenticated then he or she is redirected to AppFabric ACS identity provider selection page, if user is authenticated but has no profile then user is by default redirected to main page of site but if you have application setting with name JoinUrl then user is redirected to this URL. First case is handled by AuthorizeAttribute and the second one is handled by custom logic in ProfileRequiredAttribute class. GetProfile() extension method To get user profile using less code in places where profiles are needed I wrote GetProfile() extension method for IIdentity interface. There are some more extension methods that read out user and identity provider identifier from claims and based on this information user profile is read from database. If you take this code with copy and paste I am sure it doesn’t work for you but you get the idea. public static User GetProfile(this IIdentity identity) {     if (identity == null)         return null;       var context = HttpContext.Current;     if (context.Items["UserProfile"] != null)         return context.Items["UserProfile"] as User;       var provider = identity.GetIdentityProvider();     var nameId = identity.GetNameIdentifier();       var rep = ObjectFactory.GetInstance<IUserRepository>();     var profile = rep.GetUserByProviderAndNameId(provider, nameId);       context.Items["UserProfile"] = profile;       return profile; } To avoid round trips to database I cache user profile to current request because the chance that profile gets changed meanwhile is very minimal. The other reason is maybe more tricky – profile objects are coming from Entity Framework context and context has also HTTP request as lifecycle. Conclusion This posting gave you some ideas how to finish user profiles stuff when you use AppFabric ACS as external authentication provider. Although there was little shift between us and ASP.NET MVC with interpretation of “authorized” we were easily able to solve the problem by extending AuthorizeAttribute to get all our requirements fulfilled. We also write extension method for IIdentity that returns as user profile based on username and caches the profile in HTTP request scope.

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• Travelling MVP #2: Community event at Bucharest, Romania

  - by DigiMortal

  My second trip was to DevReach with two stops. My first stop was at Bucharest where I met with my friend Dimitar Georgiev who is one of authors of Gym Realm service. Romanian MVP Andrei Ignat was our host there and organized meeting with local community guys. With me – it was first time in my life – was one more guy from Estonia visiting DevReach and he made the whole trip with me. Bucharest We arrived to Bucharest 29.09 at night. We stayed at Hotel Michelangelo. It’s small hotel with nice rooms, free WiFi and very good service. Although my room was on the first floor there was no street noise. We visited one restaurant that offers national cuisine and it was really great. Next day we went out with local guys and had some beers in “old town”. Bucharest “old town” is nice and cozy. There are many bars open and I am sure everybody will find there some very okay place. After supper we visited one warm karaoke bar where we had beers with local guys. Andrei Ignat – karaoke star Agu Suur and Andrei Ion Rinea enjoying karaoke and tequila Community event Next day we had community event. I made my session about ASP.NET Web API and Dimitar told about how to port ASP.NET web applications to cloud environment. Sessions were held at study class of one local company. Dimitar Georgiev speaking about porting web apps to Windows Azure. As it was usual community evening and not some bigger event there were about 12 guys attending from Bucharest. There were both IT-PROs and developers and one nice thing about Bucharest community is that they are listening to you very well and they ask questions if something is unclear or if you slide over from topic they are interested in. Okay, we tried to keep up good tempo so people stay awake and I think we succeeded. After sessions we went all together to local Piranha pub that was near event venue. We had some beers with local guys and talked with them on different technology topics. It was another good and interesting evening at Bucharest. I want to go back there for sure. As it was my first trip to Bucharest and mostly I gathered experiences I think my next community trip there will be way stronger. I take it as a challenge. Plus – I have there some new friends and I want to meet them too – be it community event or not. :)

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• ASP.NET: Building tree picker dialog using jQuery UI and TreeView control

  - by DigiMortal

  Selecting things from dialogs and data represented as trees are very common things we see in business applications. In this posting I will show you how to use ASP.NET TreeView control and jQuery UI dialog component to build picker dialog that hosts tree data. Source code You can find working example with source code from my examples repository in GitHub. Please feel free to give me feedback about my examples. Source code repository GitHub Building dialog box As I don’t like to invent wheels then I will use jQuery UI to solve the question related to dialogs. If you are not sure how to include jQuery UI to your page then take a look at source code - GitHub also allows you to browse files without downloading them. I add some jQuery based JavaScript to my page head to get dialog and button work. <script type="text/javascript">     $(function () {         $("#dialog-form").dialog({             autoOpen: false,             modal: true         });         $("#pick-node")             .button()             .click(function () {                 $("#dialog-form").dialog("open");                 return false;             });     }); </script> Here is the mark-up of our form’s main content area. <div id="dialog-form" title="Select node">     <asp:TreeView ID="TreeView1" runat="server" ShowLines="True"          ClientIDMode="Static" HoverNodeStyle-CssClass="SelectedNode">         <Nodes>             <asp:TreeNode Text="Root" Value="Root">                 <asp:TreeNode Text="Child1" Value="Child1">                     <asp:TreeNode Text="Child1.1" Value="Child1.1" />                     <asp:TreeNode Text="Child1.2" Value="Child1.2" />                 </asp:TreeNode>                 <asp:TreeNode Text="Child2" Value="Child2">                     <asp:TreeNode Text="Child2.1" Value="Child2.1" />                     <asp:TreeNode Text="Child2.2" Value="Child2.2" />                 </asp:TreeNode>             </asp:TreeNode>         </Nodes>     </asp:TreeView>     &nbsp; </div> <button id="pick-node">Pick user</button> Notice that our mark-up is very compact for what we will achieve. If you are going to use it in some real-world application then this mark-up gets even shorter – I am sure that in most cases the data you display in TreeView comes from database or some domain specific data source. Hacking TreeView TreeView needs some little hacking to make it work as client-side component. Be warned that if you need more than I show you here you need to write a lot of JavaScript code. For more advanced scenarios I suggest you to use some jQuery based tree component. This example works for you if you need something done quickly. Number one problem is getting over the postbacks because in our scenario postbacks only screw up things. Also we need to find a way how to let our client-side code to know that something was selected from TreeView. We solve these to problems at same time: let’s move to JavaScript links. We have to make sure that when user clicks the node then information is sent to some JavaScript function. Also we have to make sure that this function returns something that is not processed by browser. My function is here. <script type="text/javascript">     function         $("#dialog-form").dialog("close");         alert("You selected: " + value + " - " + text);         return undefined;     } </script> Notice that this function returns undefined. You get the better idea why I did so if you look at server-side code that corrects NavigateUrl properties of TreeView nodes. protected override void OnPreRender(EventArgs e) {     base.OnPreRender(e);                 if (IsPostBack)         return;     SetSelectNodeUrls(TreeView1.Nodes); } private void SetSelectNodeUrls(TreeNodeCollection nodes) {     foreach (TreeNode node in nodes)     {         node.NavigateUrl = "javascript:selectNode('" + node.Value +                             "','" + node.Text + "');";         SetSelectNodeUrls(node.ChildNodes);     }        } Now we have TreeView that renders nodes the way that postback doesn’t happen anymore. Instead of postback our callback function is used and provided with selected values. In this function we are free to use node text and value as we like. Result I applied some more bells and whistles and sample data to source code to make my sample more informative. So, here is my final dialog box. Seems very basic but it is not hard to make it look more professional using style sheets. Conclusion jQuery components and ASP.NET controls have both their strong sides and weaknesses. In this posting I showed you how you can quickly produce good results when combining jQuery  and ASP.NET controls without pushing to the limits. We used simple hack to get over the postback issue of TreeView control and we made it work as client-side component that is initialized in server. You can find many other good combinations that make your UI more user-friendly and easier to use.

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• Using runtime checking of code contracts in Visual Studio 2010

  - by DigiMortal

  In my last posting about code contracts I introduced how to check input parameters of randomizer using static contracts checking. But you can also compile code contracts to your assemblies and use them also in runtime. In this posting I will show you simple example about runtime checking of code contracts. NB! If you want to play with code and try out things described here feel free to download example solution. if you are speaker and want to use this solution as a part of your sessions then feel free to do so, but don’t forget to refer me and this blog as source of this solution. And please let me know about your session. As a speaker I am very interested about it. :) To see how code contracts are checked at runtime we have to enable runtime checking from project properties. Make sure you have checked the box “Perform Runtime Contract Checking” and make sure you select “Full” from dropdown. These parts are in red box on the screenshot below. Visual Studio 2010 settings for code contracts. Runtime Checking is turned on and checks are made only in public surface. Click on image to see it at original size.  Save project settings. Then compile code and run it. As soon as code execution hits the call to GetRandomFromRangeContracted() exception is thrown. If you are not currently playing with solution referred above take a look at the following screenshot. Visual Studio 2010 runtime checking of code contracts. Exception of type ContractException is thrown when contract is violated. Click on image to see it at original size.  The exact type of exception is ContractException and it is defined in System.Diagnostics.Contracts.__ContractsRuntime namespace. In our example the message of exception is following: "Precondition failed: min < max  Min must be less than max" Besides the description we inserted for the case contract violation the message also contains violated contract type. In this case the type of contract is Precondition. Conclusion Using runtime checking of code contracts enables you to take code contracts with your code and have them checked every time when your methods are called. This way you can assure that all conditions are met to run method or exception is thrown and calling system has to handle the situation.

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• Book review: Peopleware: Productive Projects and Teams

  - by DigiMortal

     Peopleware by Tom DeMarco and Timothy Lister is golden classic book that can be considered as mandatory reading for software project managers, team leads, higher level management and board members of software companies. If you make decisions about people then you cannot miss this book. If you are already good on managing developers then this book can make you even better – you will learn new stuff about successful development teams for sure. Why peopleware? Peopleware gives you very good hints about how to build up working environment for project teams where people can really do their work. Book also covers team building topics that are also important reading. As software developer I found practically all points in this book to be accurate and valid. Many times I have found my self thinking about same things and Peopleware made me more confident about my opinions. Peopleware covers also time management and planning topics that help you do way better job on using developers time effectively by minimizing the amount of interruptions by phone calls, pointless meetings and i-want-to-know-what-are-you-doing-right-now questions by managers who doesn’t write code anyway. I think if you follow suggestions given by Peopleware your developers are very happy. I suggest you to also read another great book – Death March by Edward Yourdon. Death March describes you effectively what happens when good advices given by Peopleware are totally ignored or worse yet – people are treated exactly opposite way. I consider also Death March as golden classics and I strongly recommend you to read this book too. Table of Contents Acknowledgments Preface to the Second Edition Preface to the First Edition Part 1: Managing the Human Resource Chapter 1: Somewhere Today, a Project Is Failing Chapter 2: Make a Cheeseburger, Sell a Cheeseburger Chapter 3: Vienna Waits for You Chapter 4: Quality-If Time Permits Chapter 5: Parkinson's Law Revisited Chapter 6: Laetrile Part II: The Office Environment Chapter 7: The Furniture Police Chapter 8: "You Never Get Anything Done Around Here Between 9 and 5" Chapter 9: Saving Money on Space Intermezzo: Productivity Measurement and Unidentified Flying Objects Chapter 10: Brain Time Versus Body Time Chapter 11: The Telephone Chapter 12: Bring Back the Door Chapter 13: Taking Umbrella Steps Part III: The Right People Chapter 14: The Hornblower Factor Chapter 15: Hiring a Juggler Chapter 16: Happy to Be Here Chapter 17: The Self-Healing System Part IV: Growing Productive Teams Chapter 18: The Whole Is Greater Than the Sum of the Parts Chapter 19: The Black Team Chapter 20: Teamicide Chapter 21: A Spaghetti Dinner Chapter 22: Open Kimono Chapter 23: Chemistry for Team Formation Part V: It't Supposed to Be Fun to Work Here Chapter 24: Chaos and Order Chapter 25: Free Electrons Chapter 26: Holgar Dansk Part VI: Son of Peopleware Chapter 27: Teamicide, Revisited Chapter 28: Competition Chapter 29: Process Improvement Programs Chapter 30: Making Change Possible Chapter 31: Human Capital Chapter 32:Organizational Learning Chapter 33: The Ultimate Management Sin Is Chapter 34: The Making of Community Notes Bibliography Index About the Authors

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• ASP.NET: Using pickup directory for outgoing e-mails

  - by DigiMortal

  Sending e-mails out from web applications is very common task. When we are working on or test our systems with real e-mail addresses we don’t want recipients to receive e-mails (specially if we are using some subset of real data9. In this posting I will show you how to make ASP.NET SMTP client to write e-mails to disc instead of sending them out. SMTP settings for web application I have seen many times the code where all SMTP information is kept in app settings just to read them in code and give to SMTP client. It is not necessary because we can define all these settings under system.web => mailsettings node. If you are using web.config to keep SMTP settings then all you have to do in your code is just to create SmtpClient with empty constructor. var smtpClient = new SmtpClient(); Empty constructor means that all settings are read from web.config file. What is pickup directory? If you want drastically raise e-mail throughput of your SMTP server then it is not very wise plan to communicate with it using SMTP protocol. it adds only additional overhead to your network and SMTP server. Okay, clients make connections, send messages out and it is also overhead we can avoid. If clients write their e-mails to some folder that SMTP server can access then SMTP server has e-mail forwarding as only resource-eager task to do. File operations are way faster than communication over SMTP protocol. The directory where clients write their e-mails as files is called pickup directory. By example, Exchange server has support for pickup directories. And as there are applications with a lot of users who want e-mail notifications then .NET SMTP client supports writing e-mails to pickup directory instead of sending them out. How to configure ASP.NET SMTP to use pickup directory? Let’s say, it is more than easy. It is very easy. This is all you need. <system.net>   <mailSettings>     <smtp deliveryMethod="SpecifiedPickupDirectory">       <specifiedPickupDirectory pickupDirectoryLocation="c:\temp\maildrop\"/>     </smtp>   </mailSettings> </system.net> Now make sure you don’t miss come points: Pickup directory must physically exist because it is not created automatically. IIS (or Cassini) must have write permissions to pickup directory. Go through your code and look for hardcoded SMTP settings. Also take a look at all places in your code where you send out e-mails that there are not some custom settings used for SMTP! Also don’t forget that your mails will be written now to pickup directory and they are not sent out to recipients anymore. Advanced scenario: configuring SMTP client in code In some advanced scenarios you may need to support multiple SMTP servers. If configuration is dynamic or it is not kept in web.config you need to initialize your SmtpClient in code. This is all you need to do. var smtpClient = new SmtpClient(); smtpClient.DeliveryMethod = SmtpDeliveryMethod.SpecifiedPickupDirectory; smtpClient.PickupDirectoryLocation = pickupFolder; Easy, isn’t it? i like when advanced scenarios end up with simple and elegant solutions but not with rocket science. Note for IIS SMTP service SMTP service of IIS is also able to use pickup directory. If you have set up IIS with SMTP service you can configure your ASP.NET application to use IIS pickup folder. In this case you have to use the following setting for delivery method. SmtpDeliveryMethod.PickupDirectoryFromIis You can set this setting also in web.config file. <system.net>   <mailSettings>     <smtp deliveryMethod="PickupDirectoryFromIis" />   </mailSettings> </system.net> Conclusion Who was still using different methods to avoid sending e-mails out in development or testing environment can now remove all the bad code from application and live on mail settings of ASP.NET. It is easy to configure and you have less code to support e-mails when you use built-in e-mail features wisely.

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• ASP.NET: Serializing and deserializing JSON objects

  - by DigiMortal

  ASP.NET offers very easy way to serialize objects to JSON format. Also it is easy to deserialize JSON objects using same library. In this posting I will show you how to serialize and deserialize JSON objects in ASP.NET. All required classes are located in System.Servicemodel.Web assembly. There is namespace called System.Runtime.Serialization.Json for JSON serializer. To serialize object to stream we can use the following code. var serializer = new DataContractJsonSerializer(typeof(MyClass)); serializer.WriteObject(myStream, myObject); To deserialize object from stream we can use the following code. CopyStream() is practically same as my Stream.CopyTo() extension method. var serializer = new DataContractJsonSerializer(typeof(MyClass));   using(var stream = response.GetResponseStream()) using (var ms = new MemoryStream()) {     CopyStream(stream, ms);     results = serializer.ReadObject(ms) as MyClass; } Why I copied data from response stream to memory stream? Point is simple – serializer uses some stream features that are not supported by response stream. Using memory stream we can deserialize object that came from web.

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• Code Information Indicators in Visual Studio 2013

  - by DigiMortal

  Visual Studio 2013 introduces new code editor enhancement called Code Information Indicators (CII). CII is set of code editor extensions that make it easier to get information about code structure and changes. Also tests and test results can be easily accessible from code editor. In this posting I will introduce you most important new code indicators. Read more from my new blog @ gunnarpeipman.com

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• Making WIF local STS to work with your ASP.NET application

  - by DigiMortal

  Making Windows Identity Foundation (WIF) STS test application work with your solution is not as straightforward process as you can read from books and articles. There are some tricks and some configuration modifications you must do to get things work. Fortunately these steps are simple one. 1. Move your application to IIS or IIS Express If your application uses development web server that ships with Visual Studio then make your application use IIS or IIS Express. You get simple support for IIS Express to Visual Studio 2010 after installing Visual Studio 2010 SP1. You can read more from my blog posting Visual Studio 2010 SP1 Beta supports IIS Express. NB! You don’t have to move your dummy STS project to IIS. 2. Change request validation mode to ASP.NET 2.0 As a next thing you will get the following error when coming back from dummy STS service: HttpRequestValidationException (0x80004005): A potentially dangerous Request.Form value was detected from the client. Open web.config of your application and add the following line before </system.web>: <httpRuntime requestValidationMode="2.0" /> Now you are done with configuring web application to work with STS.

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• Who is code wanderer?

  - by DigiMortal

  In every area of life there are people with some bad habits or misbehaviors that affect the work process. Software development is also not free of this kind of people. Today I will introduce you code wanderer. Who is code wanderer? Code wandering is more like bad habit than serious diagnose. Code wanderers tend to review and “fix” source code in files written by others. When code wanderer has some free moments he starts to open the code files he or she has never seen before and starts making little fixes to these files. Why is code wanderer dangerous? These fixes seem correct and are usually first choice to do when considering nice code. But as changes are made by coder who has no idea about the code he or she “fixes” then “fixing” usually ends up with messing up working code written by others. Often these “fixes” are not found immediately because they doesn’t introduce errors detected by compilers. So these “fixes” find easily way to production environments because there is also very good chance that “fixed” code goes through all tests without any problems. How to stop code wanderer? The first thing is to talk with person and explain him or her why those changes are dangerous. It is also good to establish rules that state clearly why, when and how can somebody change the code written by other people. If this does not work it is possible to isolate this person so he or she can post his or her changes to code repository as patches and somebody reviews those changes before applying them.

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• Example: Controlling randomizer using code contracts

  - by DigiMortal

  One cool addition to Visual Studio 2010 is support for code contracts. Code contracts make sure that all conditions under what method is supposed to run correctly are met. Those who are familiar with unit tests will find code contracts easy to use. In this posting I will show you simple example about static contract checking (example solution is included). To try out code contracts you need at least Visual Studio 2010 Standard Edition. Also you need code contracts package. You can download package from DevLabs Code Contracts page. NB! Speakers, you can use the example solution in your presentations as long as you mention me and this blog in your sessions. Solution has readme.txt file that gives you steps to go through when presenting solution in sessions. This blog posting is companion posting for Visual Studio solution referred below. As an example let’s look at the following class. public class Randomizer {     public static int GetRandomFromRange(int min, int max)     {         var rnd = new Random();         return rnd.Next(min, max);     }       public static int GetRandomFromRangeContracted(int min, int max)     {         Contract.Requires(min < max, "Min must be less than max");           var rnd = new Random();         return rnd.Next(min, max);     } } GetRandomFromRange() method returns results without any checking. GetRandomFromRangeContracted() uses one code contract that makes sure that minimum value is less than maximum value. Now let’s run the following code. class Program {     static void Main(string[] args)     {         var random1 = Randomizer.GetRandomFromRange(0, 9);         Console.WriteLine("Random 1: " + random1);           var random2 = Randomizer.GetRandomFromRange(1, 1);         Console.WriteLine("Random 2: " + random2);           var random3 = Randomizer.GetRandomFromRangeContracted(5, 5);         Console.WriteLine("Random 3: " + random3);           Console.WriteLine(" ");         Console.WriteLine("Press any key to exit ...");         Console.ReadKey();     } } As we have not turned on support for code contracts the code runs without any problems and we get no warnings by Visual Studio that something is wrong. Now let’s turn on static checking for code contracts. As you can see then code still compiles without any errors but Visual Studio warns you about possible problems with contracts. Click on image to see it at original size.  When we open Error list and run our application we get the following output to errors list. Note that these messages are not shown immediately. There is little delay between application starting and appearance of these messages. So wait couple of seconds before going out of your mind. Click on image to see it at original size.  If you look at these warnings you can see that warnings show you illegal calls and also contracts against what they are going. Third warning points to GetRandomFromRange() method and shows that there should be also problem that can be detected by contract. Download Code Contracts example VS2010 solution | 30KB

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• Code contracts and inheritance

  - by DigiMortal

  In my last posting about code contracts I introduced you how to force code contracts to classes through interfaces. In this posting I will go step further and I will show you how code contracts work in the case of inherited classes. As a first thing let’s take a look at my interface and code contracts. [ContractClass(typeof(ProductContracts))] public interface IProduct {     int Id { get; set; }     string Name { get; set; }     decimal Weight { get; set; }     decimal Price { get; set; } }   [ContractClassFor(typeof(IProduct))] internal sealed class ProductContracts : IProduct {     private ProductContracts() { }       int IProduct.Id     {         get         {             return default(int);         }         set         {             Contract.Requires(value > 0);         }     }       string IProduct.Name     {         get         {             return default(string);         }         set         {             Contract.Requires(!string.IsNullOrWhiteSpace(value));             Contract.Requires(value.Length <= 25);         }     }       decimal IProduct.Weight     {         get         {             return default(decimal);         }         set         {             Contract.Requires(value > 3);             Contract.Requires(value < 100);         }     }       decimal IProduct.Price     {         get         {             return default(decimal);         }         set         {             Contract.Requires(value > 0);             Contract.Requires(value < 100);         }     } } And here is the product class that inherits IProduct interface. public class Product : IProduct {     public int Id { get; set; }     public string Name { get; set; }     public virtual decimal Weight { get; set; }     public decimal Price { get; set; } } if we run this code and violate the code contract set to Id we will get ContractException. public class Program {     static void Main(string[] args)     {         var product = new Product();         product.Id = -100;     } }   Now let’s make Product to be abstract class and let’s define new class called Food that adds one more contract to Weight property. public class Food : Product {     public override decimal Weight     {         get         {             return base.Weight;         }         set         {             Contract.Requires(value > 1);             Contract.Requires(value < 10);               base.Weight = value;         }     } } Now we should have the following rules at place for Food: weight must be greater than 1, weight must be greater than 3, weight must be less than 100, weight must be less than 10. Interesting part is what happens when we try to violate the lower and upper limits of Food weight. To see what happens let’s try to violate rules #2 and #4. Just comment one of the last lines out in the following method to test another assignment. public class Program {     static void Main(string[] args)     {         var food = new Food();         food.Weight = 12;         food.Weight = 2;     } } And here are the results as pictures to see where exceptions are thrown. Click on images to see them at original size. Violation of lower limit. Violation of upper limit. As you can see for both violations we get ContractException like expected. Code contracts inheritance is powerful and at same time dangerous feature. Although you can always narrow down the conditions that come from more general classes it is possible to define impossible or conflicting contracts at different points in inheritance hierarchy.

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• Blogging locally and globally–my experience

  - by DigiMortal

  In Baltic MVP Summit 2011 there was discussion about having two blogs - one for local and another for global audience – and how to publish once written information in these blogs. There are many ways how to optimize your blogging activities if you have more than one audience and here you can find my experiences, best practices and advices about this topic. My two blogs I have to working blogs: this one here technology and programming blog for local market My local blog is almost five years old and it makes it one of the oldest company blogs in Estonia. It is still active and I write there as much as I have time for it. This blog here is active since September 2007, so it is about 3.5 years old right now. Both of these blogs are  my major hits in my MVP carrier and they have very good web statistics too. My local blog My local blog is about programming, web and technology. It has way wider target audience then this blog here has. By example, in my local blog I blog also about local events, cool new concept phones, different webs providing some interesting services etc. But local guys can find there also my postings about how to solve one or another programming problem and postings about Microsoft technologies I am playing with. This far my local blog has a lot of readers for such a small country that Estonia is. This blog has made me a lot of cool contacts and I have had there a lot of interesting discussions about different technical topics. Why I started this blog? Living in small country is different than living in big country. In small country you have less people and therefore smaller audience so you have to target more than one technical topic to find enough readers. In a same time you are still interested in your main topics and you want to reach to more people who are sharing same interests with you. Practically one day y will grow out from local market and you go global. This is how this blog was born. Was it worth to create, promote and mess with it? Every second I have put on my time to this blog has been worth of it. Thanks to this blog I have found new good friends and without them I think it is more boring to work on different problems and solutions. Defining target audiences One thing you should always do when having more than one blog is defining target audiences. If you are just technomaniac interested in sharing your stuff and make some new friends and have something to write to your MVP nomination form then you don’t have to go through complex targeting process. You can do it simple way and same effectively. Here is how I defined target audiences to my blogs: local blog – reader of my local blog is IT professional, software developer, technology innovator or just some guy who is interested in technology,   this blog – reader of this blog is experienced professional software developer who works on Microsoft technologies or software developer who is open minded and open to new technologies and interesting solutions to development problems. You can see how local blog – due to small market with less people – has wider definition for audience while this blog is heavily targeted to Microsoft technologies and specially to software development. On practical side these decisions are also made well I think because it is very hard to build up popular common IT blog. On global level it is better to target some specific niche and find readers who are professionals on your favorite topics. Thanks to this blog I have found new friends who are professional developers and I am very happy about all the discussions I have had with them. Publishing content to different blogs My local blog and this blog have some overlapping topics like .NET, databases and SEO. Due to this overlapping there is question: when I write posting to my local blog then should I have to publish same thing in my global blog? And if I write something to my global blog then should I publish same thing also in my local blog? Well, it really depends on the definition of your target audiences. If they match then of course it is good idea to translate you post and publish it also to another blog. But if you have different audiences then you may need to modify your posting before publishing it. The questions you have to answer are: is target audience interested in this topic? is target audience expecting more specific and deeper handling of this topic or are they expecting more general handling of topic? is the problem you are discussing actual for target audience or not? You have to answer these questions and after that make your decision. If you need to modify your original posting then take some time and do it. Provide quality to all your readers because they will respect you if you respect them. Cross-posting and referencing It is tempting to save time that preparing some blog post takes and if you have are done with posting in one blog it may seem like good idea to make short posting to another blog and add reference to first one where topic is discussed longer. Well, don’t do it – all your readers expect good quality content from you and jumping from one blog post to another is disturbing for them. Of course, there is problem with differences between target audiences. You may have wider target audience and some people may be interested in more specific handling of topic. In this case feel free to refer your blog you are writing in english. This is not working very well in opposite direction because almost all my global blog readers understand english but not estonian. By example, estonian language is complex one and online translating tools make very poor translations from estonian language. This is why I don’t even plan to publish postings here that refer to my local blog for more information. I am keeping these two blogs as two different worlds and if there is posting that fits well to both blogs I will write my posting to one blog and then answer previous three questions before posting same thing to another blog. Conclusion Growing out of your local market is not anything mysterious if you are living in small country. As it is harder to find people there who are interested in same topics with you then sooner or later you will start finding these new contacts from global audience. Global audience is bigger and to be visible there you must provide high quality content to your audience. It is something you will learn over time and you will learn every day something new when you are posting to your global blog. You may ask: if global blog is much more complex thing to do then is it worth to do at all? My answer is: yes, do it for sure. It is not easy thing to do when you start but if you work on your global blog and improve it over time you will get over all obstacles pretty soon. Just don’t forget one thing – content is king and your readers expect high quality from you.

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• Code Contracts: How they look after compiling?

  - by DigiMortal

  When you are using new tools that make also something at code level then it is good idea to check out what additions are made to code during compilation. Code contracts have simple syntax when we are writing code at Visual Studio but what happens after compilation? Are our methods same as they look in code or are they different after compilation? In this posting I will show you how code contracts look after compiling. In my previous examples about code contracts I used randomizer class with method called GetRandomFromRangeContracted. public int GetRandomFromRangeContracted(int min, int max) {     Contract.Requires<ArgumentOutOfRangeException>(         min < max,         "Min must be less than max"     );       Contract.Ensures(         Contract.Result<int>() >= min &&         Contract.Result<int>() <= max,         "Return value is out of range"     );       return _generator.Next(min, max); } Okay, it is nice to dream about similar code when we open our assembly with Reflector and disassemble it. But… this time we have something interesting. While reading this code don’t feel uncomfortable about the names of variables. This is disassembled code. .NET Framework internally allows these names. It is our compilators that doesn’t accept them when we are building our code. public int GetRandomFromRangeContracted(int min, int max) {     int Contract.Old(min);     int Contract.Old(max);     if (__ContractsRuntime.insideContractEvaluation <= 4)     {         try         {             __ContractsRuntime.insideContractEvaluation++;             __ContractsRuntime.Requires<ArgumentOutOfRangeException>(                min < max,                "Min must be less than max", "min < max");         }         finally         {             __ContractsRuntime.insideContractEvaluation--;         }     }     try     {         Contract.Old(min) = min;     }     catch (Exception exception1)     {         if (exception1 == null)         {             throw;         }     }     try     {         Contract.Old(max) = max;         catch (Exception exception2)     {         if (exception2 == null)         {             throw;         }     }     int CS$1$0000 = this._generator.Next(min, max);     int Contract.Result<int>() = CS$1$0000;     if (__ContractsRuntime.insideContractEvaluation <= 4)     {         try         {             __ContractsRuntime.insideContractEvaluation++;             __ContractsRuntime.Ensures(                (Contract.Result<int>() >= Contract.Old(min)) &&                (Contract.Result<int>() <= Contract.Old(max)),                "Return value is out of range",                "Contract.Result<int>() >= min && Contract.Result<int>() <= max");         }         finally         {             __ContractsRuntime.insideContractEvaluation--;         }     }     return Contract.Result<int>(); } As we can see then contracts are not simply if-then-else checks and exceptions throwing. We can see that there is counter that is incremented before checks and decremented after these whatever the result of check was. One thing that is annoying for me are null checks for exception1 and exception2. Is there really some situation possible when null is thrown instead of some instance that is Exception or that inherits from exception? Conclusion Code contracts are more complex mechanism that it seems when we look at it on our code level. Internally there are done more things than we know. I don’t say it is wrong, it is just good to know how our code looks after compiling. Looking at this example it is sure we need also performance tests for contracted code to see how heavy is their impact to system performance when we run code that makes heavy use of code contracts.

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• How to avoid the exception “Substitution controls cannot be used in cached User Controls or cached M

  - by DigiMortal

  Recently I wrote example about using user controls with donut caching. Because cache substitutions are not allowed inside partially cached controls you may get the error Substitution controls cannot be used in cached User Controls or cached Master Pages when breaking this rule. In this posting I will introduce some strategies that help to avoid this error. How Substitution control checks its location? Substitution control uses the following check in its OnPreRender method. protected internal override void OnPreRender(EventArgs e) {     base.OnPreRender(e);     for (Control control = this.Parent; control != null;          control = control.Parent)     {         if (control is BasePartialCachingControl)         {             throw new HttpException(SR.GetString("Substitution_CannotBeInCachedControl"));         }     } } It traverses all the control tree up to top from its parent to find at least one control that is partially cached. If such control is found then exception is thrown. Reusing the functionality If you want to do something by yourself if your control may cause exception mentioned before you can use the same code. I modified the previously shown code to be method that can be easily moved to user controls base class if you have some. If you don’t you can use it in controls where you need this check. protected bool IsInsidePartialCachingControl() {     for (Control control = Parent; control != null;         control = control.Parent)         if (control is BasePartialCachingControl)             return true;       return false; } Now it is up to you how to handle the situation where your control with substitutions is child of some partially cache control. You can add here also some debug level output so you can see exactly what controls in control hierarchy are cached and cause problems.

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• Reading OpenDocument spreadsheets using C#

  - by DigiMortal

  Excel with its file formats is not the only spreadsheet application that is widely used. There are also users on Linux and Macs and often they are using OpenOffice and other open-source office packages that use ODF instead of OpenXML. In this post I will show you how to read Open Document spreadsheet in C#. Importer as example My previous post about importers showed you how to build flexible importers support to your web application. This post introduces you practical example of one of my importers. Of course, sensitive code is omitted. We start with ODS importer class and we add new methods as we go. public class OdsImporter : ImporterBase {     public OdsImporter()     {     }       public override string[] SupportedFileExtensions     {         get { return new[] { "ods" }; }     }       public override ImportResult Import(Stream fileStream, long companyId, short year)     {         string contentXml = GetContentXml(fileStream);           var result = new ImportResult();         var doc = XDocument.Parse(contentXml);           var rows = doc.Descendants("{urn:oasis:names:tc:opendocument:xmlns:table:1.0}table-row").Skip(1);           foreach (var row in rows)         {             ImportRow(row, companyId, year, result);         }           return result;     } } The class given here just extends base class for importers (previous post uses interface but as I already told there you move to abstract base class when writing code for real projects). Import method reads data from *.ods file, parses it (it is XML), finds all data rows and imports data. As you may see then first row is skipped. This is because the first row on my sheet is always headers row. Reading ODS file Our import method starts with getting XML from *.ods file. ODS files like OpenXml files are zipped containers that contain different files. We need content.xml as all data is kept there. To get the contents of file we use SharpZipLib library to read uploaded file as *.zip file. private static string GetContentXml(Stream fileStream) {     var contentXml = "";       using (var zipInputStream = new ZipInputStream(fileStream))     {         ZipEntry contentEntry = null;         while ((contentEntry = zipInputStream.GetNextEntry()) != null)         {             if (!contentEntry.IsFile)                 continue;             if (contentEntry.Name.ToLower() == "content.xml")                 break;         }           if (contentEntry.Name.ToLower() != "content.xml")         {             throw new Exception("Cannot find content.xml");         }           var bytesResult = new byte[] { };         var bytes = new byte[2000];         var i = 0;           while ((i = zipInputStream.Read(bytes, 0, bytes.Length)) != 0)         {             var arrayLength = bytesResult.Length;             Array.Resize<byte>(ref bytesResult, arrayLength + i);             Array.Copy(bytes, 0, bytesResult, arrayLength, i);         }         contentXml = Encoding.UTF8.GetString(bytesResult);     }     return contentXml; } If here is content.xml file then we stop browsing the file. We read this file to memory and return it as UTF-8 format string. Importing rows Our last task is to import rows. We use special method for this as we have to handle some tricks here. To keep files smaller the cell count on row is not always the same. If we have more than one empty cell one after another then ODS keeps only one cell for sequential empty cells. This cell has attribute called number-columns-repeated and it’s value is set to the number of sequential empty cells. This is why we use two indexers for cells collection. private void ImportRow(XElement row, ImportResult result) {     var cells = (from c in row.Descendants()                 where c.Name == "{urn:oasis:names:tc:opendocument:xmlns:table:1.0}table-cell"                 select c).ToList();       var dto = new DataDto();       var count = cells.Count;     var j = -1;       for (var i = 0; i < count; i++)     {         j++;         var cell = cells[i];         var attr = cell.Attribute("{urn:oasis:names:tc:opendocument:xmlns:table:1.0}number-columns-repeated");         if (attr != null)         {             var numToSkip = 0;             if (int.TryParse(attr.Value, out numToSkip))             {                 j += numToSkip - 1;             }         }           if (i > 30) break;         if (j == 0)         {             dto.SomeProperty = cells[i].Value;         }         if (j == 1)         {             dto.SomeOtherProperty = cells[i].Value;         }         // some more data reading     }       // save data } You can define your own class for import results and add there all problems found during data import. Your application gets the results and shows them to user. Conclusion Reading ODS files may seem to complex task but actually it is very easy if we need only data from those documents. We can use some zip-library to get the content file and then parse it to XML. It is not hard to go through the XML but there are some optimization tricks we have to know. The code here is safe to use in web applications as it is not using any API-s that may have special needs to server and infrastructure.

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• Consuming ASP.NET Web API services from PHP script

  - by DigiMortal

  I introduced ASP.NET Web API in some of my previous posts. Although Web API is easy to use in ASP.NET web applications you can use Web API also from other platforms. This post shows you how to consume ASP.NET Web API from PHP scripts. Here are my previous posts about Web API: How content negotiation works? ASP.NET Web API: Extending content negotiation with new formats Query string based content formatting Although these posts cover content negotiation they give you some idea about how Web API works. Test application On Web API side I use the same sample application as in previous Web API posts – very primitive web application to manage contacts. Listing contacts On the other machine I will run the following PHP script that works against my Web API application: <?php   // request list of contacts from Web API $json = file_get_contents('http://vs2010dev:3613/api/contacts/'); // deserialize data from JSON $contacts = json_decode($json); ?> <html> <head>     <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> </head> <body>     <table>     <?php      foreach($contacts as $contact)     {         ?>         <tr>             <td valign="top">                 <?php echo $contact->FirstName ?>             </td>             <td valign="top">                 <?php echo $contact->LastName ?>             </td>             <td valign="middle">                 <form method="POST">                     <input type="hidden" name="id"                          value="<?php echo $contact-/>Id ?>" />                     <input type="submit" name="cmd"                          value="Delete"/>                 </form>             </td>         </tr>         <?php     }     ?>     </table> </body> </html> Notice how easy it is to handle JSON data in PHP! My PHP script produces the following output: Looks like data is here as it should be. Deleting contacts Now let’s write code to delete contacts. Add this block of code before any other code in PHP script. if(@$_POST['cmd'] == 'Delete') {     $errno = 0;     $errstr = '';     $id = @$_POST['id'];          $params = array('http' => array(               'method' => 'DELETE',               'content' => ""             ));     $url = 'http://vs2010dev:3613/api/contacts/'.$id;     $ctx = stream_context_create($params);     $fp = fopen($url, 'rb', false, $ctx);       if (!$fp) {         $res = false;       } else {         $res = stream_get_contents($fp);       }     fclose($fp);     header('Location: /json.php');     exit; } Again simple code. If we write also insert and update methods we may want to bundle those operations to single class. Conclusion ASP.NET Web API is not only ASP.NET fun. It is available also for all other platforms. In this posting we wrote simple PHP client that is able to communicate with our Web API application. We wrote only some simple code, nothing complex. Same way we can use also platforms like Java, PERL and Ruby.

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• Generating radial indicator images using C#

  - by DigiMortal

  In one of my projects I needed to draw radial indicators for processes measured in percent. Simple images like the one shown on right. I solved the problem by creating images in C# and saving them on server hard disc so if image is once generated then it is returned from disc next time. I am not master of graphics or geometrics but here is the code I wrote. Drawing radial indicator To get things done quick’n’easy way – later may some of younger developers be the one who may need to changes things – I divided my indicator drawing process to four steps shown below. 1. Fill pie 2. Draw circles 3. Fill inner circle 4. Draw text Drawing image Here is the code to draw indicators. private static void SaveRadialIndicator(int percent, string filePath) {     using (Bitmap bitmap = new Bitmap(100, 100))     using (Graphics objGraphics = Graphics.FromImage(bitmap))     {         // Initialize graphics         objGraphics.Clear(Color.White);         objGraphics.SmoothingMode = SmoothingMode.AntiAlias;         objGraphics.TextRenderingHint = TextRenderingHint.ClearTypeGridFit;           // Fill pie         // Degrees are taken clockwise, 0 is parallel with x         // For sweep angle we must convert percent to degrees (90/25 = 18/5)         float startAngle = -90.0F;                        float sweepAngle = (18.0F / 5) * percent;           Rectangle rectangle = new Rectangle(5, 5, 90, 90);         objGraphics.FillPie(Brushes.Orange, rectangle, startAngle, sweepAngle);           // Draw circles         rectangle = new Rectangle(5, 5, 90, 90);         objGraphics.DrawEllipse(Pens.LightGray, rectangle);         rectangle = new Rectangle(20, 20, 60, 60);         objGraphics.DrawEllipse(Pens.LightGray, rectangle);           // Fill inner circle with white         rectangle = new Rectangle(21, 21, 58, 58);         objGraphics.FillEllipse(Brushes.White, rectangle);           // Draw text on image         // Use rectangle for text and align text to center of rectangle         var font = new Font("Arial", 13, FontStyle.Bold);         StringFormat stringFormat = new StringFormat();         stringFormat.Alignment = StringAlignment.Center;         stringFormat.LineAlignment = StringAlignment.Center;           rectangle = new Rectangle(20, 40, 62, 20);         objGraphics.DrawString(percent + "%", font, Brushes.DarkGray, rectangle, stringFormat);           // Save indicator to file         objGraphics.Flush();         if (File.Exists(filePath))             File.Delete(filePath);           bitmap.Save(filePath, ImageFormat.Png);     }        } Using indicators on web page To show indicators on your web page you can use the following code on page that outputs indicator images: protected void Page_Load(object sender, EventArgs e) {     var percentString = Request.QueryString["percent"];     var percent = 0;     if(!int.TryParse(percentString, out percent))         return;     if(percent < 0 || percent > 100)         return;       var file = Server.MapPath("~/images/percent/" + percent + ".png");     if(!File.Exists(file))         SaveImage(percent, file);       Response.Clear();     Response.ContentType = "image/png";     Response.WriteFile(file);     Response.End(); } Om your pages where you need indicator you can set image source to Indicator.aspx (if you named your indicator handling file like this) and add percent as query string:     <img src="Indicator.aspx?percent=30" /> That’s it! If somebody knows simpler way how to generate indicators like this I am interested in your feedback.

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