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  • Generic SQL builder .NET

    - by Patrick
    I'm looking for a way to write an SQL statement in C# targeting different providers. A typical example of SQL statements differentiating is the LIMIT in PostgreSQL vs. TOP in MSSQL. Is the only way to solve SQL-syntax like the two above to write if-statements depending on which provider the user selects or using try catch statements as flow control (LIMIT didn't work, I'll try TOP instead)? I've seen the LINQ Take method, but I'm wondering if one can do this without LINQ? In other words, does C# have some generic SQL Provider class that I have failed to find that can be used?

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  • .NET & Worflow, SqlTrackingQuery.GetWorkflows() on wire correct - presented object not

    - by UKShots
    With windows workflow when using the tracking service, the SqlTrackingQuery.GetWorkflows() method returns correctly the workflow type and assembly version on the wire from the DB query - but when one comes to query the returned SqlTrackingWorkflowInstance object it's WorkflowType.AssemblyQualifiedName property is returned as the current assembly version of the workflow type (i.e. it looks to matching on FQ type name only and not version). Anyone know how to get to the actual returned data (other than either a custom query or hook)?

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  • .NET integration Framework

    - by buhtla
    Is there any kind of framework that provides some generic mechanism for integration between applications or something similar? By integration I presume data exchange (import and export) between two applications via some standard interface like Web Service.

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  • Count of Distinct Int32 Values in .NET

    - by Eric J.
    I am receiving a stream of unordered Int32 values and need to track the count of distinct values that I receive. My thought is to add the Int32 values into a HashSet<Int32>. Duplicate entries will simply not be added per the behavior of HashSet. Do I understand correctly that set membership is based on GetHashCode() and that the hash code of an Int32 is the number itself? Is there an approach that is either more CPU or more memory efficient? UPDATE The data stream is rather large. Simply using Linq to iterate the stream to get the distinct count is not what I'm after, since that would involve iterating the stream a second time.

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  • [Linq & Dictionary (.NET)] A problem with compare item value

    - by Tony
    Hi, I have defined my class: public class Host { public string Name; } then a strobgly-typed dictionary: Dictionary<string, Host> HostsTable; then I try to compare a value: if (HostsTable.Values.Where(s => s.Name == "myhostname") != null) { doSomething } and the problem is, nothing is found, even I'm sure the item is on the list. What I'm doing wrong ?

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  • .NET DB Query Without Allocations?

    - by Michael Covelli
    I have been given the task of re-writing some libraries written in C# so that there are no allocations once startup is completed. I just got to one project that does some DB queries over an OdbcConnection every 30 seconds. I've always just used .ExecuteReader() which creates an OdbcDataReader. Is there any pattern (like the SocketAsyncEventArgs socket pattern) that lets you re-use your own OdbcDataReader? Or some other clever way to avoid allocations? I haven't bothered to learn LINQ since all the dbs at work are Oracle based and the last I checked, there was no official Linq To Oracle provider. But if there's a way to do this in Linq, I could use one of the third-party ones.

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  • Communicating Between .NET Programs

    - by IronManIngellis
    I wanted to set up a simple data communication between two C# applications, and I'm not sure what the best method is in doing so. I've previously used Java Sockets and ServerSockets to get the job done, but I'm new to C#, so I've come for advice :) It's going to be two way communication with two clients exchanging strings or something of the like.

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  • Thousands separator in .Net/F#

    - by rwallace
    What's the recommended way to print an integer with thousands separator? Best I've come up with so far is let thousands(x:int64) = String.Format("{0:0,0}", x) Which works in most cases, but prints zero as 00.

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  • && Operation in .NET

    - by Ram
    Which one out of the following two should be preferred while doing && operation on two values. if (!StartTime.Equals(DateTime.MinValue) && !CreationTime.Equals(DateTime.MinValue)) Or if (!(StartTime.Equals(DateTime.MinValue) && CreationTime.Equals(DateTime.MinValue)) What is the difference between the two?

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  • .Net file writing and string splitting issues

    - by sagar
    I have a requirement where the file should be split using a given character. Default splitting options are CRLF and LF In both these cases I am splitting the line by \r\n and \r respectively. Also I have requirement where any size of file should be processed. (Processing is basically inserting the given string in a file at given position). For this I am reading the file in chunk of 1024 bytes. Then I am applying the string.Split() method. Split() method gives options for ignoring white spaces and none. I have to add back these line break characters to the line. for this I am using a binary writer and I am writing the byte array to the new file. Issue:- 1) When line break is CRLF, and the split option is NONE, while spaces are also added in the splitted array. Second option is given (to ignore white spaces) CRLF works properly. 2)Bit ignoring white space option creates other problems, as I am reading the file byte by byte I can't ignore a white space. 3)When line break characters are other than default(e.g. '|', a null value is prepended to the resulting line. Can anybody give solution to my issues?

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  • .net File.Copy very slow when copying many small files (not over network)

    - by Guavaman
    I'm making a simple folder sync backup tool for myself and ran into quite a roadblock using File.Copy. Doing tests copying a folder of ~44,000 small files (Windows mail folders) to another drive in my system, I found that using File.Copy was over 3x slower than using a command line and running xcopy to copy the same files/folders. My C# version takes over 16+ minutes to copy the files, whereas xcopy takes only 5 minutes. I've tried searching for help on this topic, but all I find is people complaining about slow file copying of large files over a network. This is neither a large file problem nor a network copying problem. I found an interesting article about a better File.Copy replacement, but the code as posted has some errors which causes problems with the stack and I am nowhere near knowledgeable enough to fix the problems in his code. Are there any common or easy ways to replace File.Copy with something more speedy?

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  • Windows Phone 7 development: reading RSS feeds

    - by DigiMortal
    One limitation on Windows Phone 7 is related to System.Net namespace classes. There is no convenient way to read data from web. There is no WebClient class. There is no GetResponse() method – we have to do it all asynchronously because compact framework has limited set of classes we can use in our applications to communicate with internet. In this posting I will show you how to read RSS-feeds on Windows Phone 7. NB! This is my draft code and it may contain some design flaws and some questionable solutions. This code is intended to use as test-drive for Windows Phone 7 CTP developer tools and I don’t suppose you are going to use this code in production environment. Current state of my RSS-reader Currently my RSS-reader for Windows Phone 7 is very simple, primitive and uses almost all defaults that come out-of-box with Windows Phone 7 CTP developer tools. My first goal before going on with nicer user interface design was making RSS-reading work because instead of convenient classes from .NET Framework we have to use very limited classes from .NET Framework CE. This is why I took the reading of RSS-feeds as my first task. There are currently more things to solve regarding user-interface. As I am pretty new to all this Silverlight stuff I am not very sure if I can modify default controls easily or should I write my own controls that have better look and that work faster. The image on right shows you how my RSS-reader looks like right now. Upper side of screen is filled with list that shows headlines from this blog. The bottom part of screen is used to show description of selected posting. You can click on the image to see it in original size. In my next posting I will show you some improvements of my RSS-reader user interface that make it look nicer. But currently it is nice enough to make sure that RSS-feeds are read correctly. FeedItem class As this is most straight-forward part of the following code I will show you RSS-feed items class first. I think we have to stop on it because it is simple one. public class FeedItem {     public string Title { get; set; }     public string Description { get; set; }     public DateTime PublishDate { get; set; }     public List<string> Categories { get; set; }     public string Link { get; set; }       public FeedItem()     {         Categories = new List<string>();     } } RssClient RssClient takes feed URL and when asked it loads all items from feed and gives them back to caller through ItemsReceived event. Why it works this way? Because we can make responses only using asynchronous methods. I will show you in next section how to use this class. Although the code here is not very good but it works like expected. I will refactor this code later because it needs some more efforts and investigating. But let’s hope I find excellent solution. :) public class RssClient {     private readonly string _rssUrl;       public delegate void ItemsReceivedDelegate(RssClient client, IList<FeedItem> items);     public event ItemsReceivedDelegate ItemsReceived;       public RssClient(string rssUrl)     {         _rssUrl = rssUrl;     }       public void LoadItems()     {         var request = (HttpWebRequest)WebRequest.Create(_rssUrl);         var result = (IAsyncResult)request.BeginGetResponse(ResponseCallback, request);     }       void ResponseCallback(IAsyncResult result)     {         var request = (HttpWebRequest)result.AsyncState;         var response = request.EndGetResponse(result);           var stream = response.GetResponseStream();         var reader = XmlReader.Create(stream);         var items = new List<FeedItem>(50);           FeedItem item = null;         var pointerMoved = false;           while (!reader.EOF)         {             if (pointerMoved)             {                 pointerMoved = false;             }             else             {                 if (!reader.Read())                     break;             }               var nodeName = reader.Name;             var nodeType = reader.NodeType;               if (nodeName == "item")             {                 if (nodeType == XmlNodeType.Element)                     item = new FeedItem();                 else if (nodeType == XmlNodeType.EndElement)                     if (item != null)                     {                         items.Add(item);                         item = null;                     }                   continue;             }               if (nodeType != XmlNodeType.Element)                 continue;               if (item == null)                 continue;               reader.MoveToContent();             var nodeValue = reader.ReadElementContentAsString();             // we just moved internal pointer             pointerMoved = true;               if (nodeName == "title")                 item.Title = nodeValue;             else if (nodeName == "description")                 item.Description =  Regex.Replace(nodeValue,@"<(.|\n)*?>",string.Empty);             else if (nodeName == "feedburner:origLink")                 item.Link = nodeValue;             else if (nodeName == "pubDate")             {                 if (!string.IsNullOrEmpty(nodeValue))                     item.PublishDate = DateTime.Parse(nodeValue);             }             else if (nodeName == "category")                 item.Categories.Add(nodeValue);         }           if (ItemsReceived != null)             ItemsReceived(this, items);     } } This method is pretty long but it works. Now let’s try to use it in Windows Phone 7 application. Using RssClient And this is the fragment of code behing the main page of my application start screen. You can see how RssClient is initialized and how items are bound to list that shows them. public MainPage() {     InitializeComponent();       SupportedOrientations = SupportedPageOrientation.Portrait | SupportedPageOrientation.Landscape;     listBox1.Width = Width;       var rssClient = new RssClient("http://feedproxy.google.com/gunnarpeipman");     rssClient.ItemsReceived += new RssClient.ItemsReceivedDelegate(rssClient_ItemsReceived);     rssClient.LoadItems(); }   void rssClient_ItemsReceived(RssClient client, IList<FeedItem> items) {     Dispatcher.BeginInvoke(delegate()     {         listBox1.ItemsSource = items;     });            } Conclusion As you can see it was not very hard task to read RSS-feed and populate list with feed entries. Although we are not able to use more powerful classes that are part of full version on .NET Framework we can still live with limited set of classes that .NET Framework CE provides.

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  • Configure Forms based authentication in SharePoint 2010

    - by sreejukg
      Configuring form authentication is a straight forward task in SharePoint. Mostly public facing websites built on SharePoint requires form based authentication. Recently, one of the WCM implementation where I was included in the project team required registration system. Any internet user can register to the site and the site offering them some membership specific functionalities once the user logged in. Since the registration open for all, I don’t want to store all those users in Active Directory. I have decided to use Forms based authentication for those users. This is a typical scenario of form authentication in SharePoint implementation. To implement form authentication you require the following A data store where you are storing the users – technically this can be active directory, SQL server database, LDAP etc. Form authentication will redirect the user to the login page, if the request is not authenticated. In the login page, there will be controls that validate the user inputs against the configured data store. In this article, I am going to use SQL server database with ASP.Net membership API’s to configure form based authentication in SharePoint 2010. This article assumes that you have SQL membership database available. I already configured the membership and roles database using aspnet_regsql command. If you want to know how to configure membership database using aspnet_regsql command, read the below blog post. http://weblogs.asp.net/sreejukg/archive/2011/06/16/usage-of-aspnet-regsql-exe-in-asp-net-4.aspx The snapshot of the database after implementing membership and role manager is as follows. I have used the database name “aspnetdb_claim”. Make sure you have created the database and make sure your database contains tables and stored procedures for membership. Create a web application with claims based authentication. This article assumes you already created a web application using claims based authentication. If you want to enable forms based authentication in SharePoint 2010, you must enable claims based authentication. Read this post for creating a web application using claims based authentication. http://weblogs.asp.net/sreejukg/archive/2011/06/15/create-a-web-application-in-sharepoint-2010-using-claims-based-authentication.aspx  You make sure, you have selected enable form authentication, and then selected Membership provider and Role manager name. To make sure you are done with the configuration, navigate to central administration website, from central administration, navigate to the Web Applications page, select the web application and click on icon, you will see the authentication providers for the current web application. Go to the section Claims authentication types, and make sure you have enabled forms based authentication. As mentioned in the snapshot, I have named the membership provider as SPFormAuthMembership and role manager as SPFormAuthRoleManager. You can choose your own names as you need. Modify the configuration files(Web.Config) to enable form authentication There are three applications that needs to be configured to support form authentication. The following are those applications. Central Administration If you want to assign permissions to web application using the credentials from form authentication, you need to update Central Administration configuration. If you do not want to access form authentication credentials from Central Administration, just leave this step.  STS service application Security Token service is the service application that issues security token when users are logging in. You need to modify the configuration of STS application to make sure users are able to login. To find the STS application, follow the following steps Go to the IIS Manager Expand the sites Node, you will see SharePoint Web Services Expand SharePoint Web Services, you can see SecurityTokenServiceApplication Right click SecuritytokenServiceApplication and click explore, it will open the corresponding file system. By default, the path for STS is C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\WebServices\SecurityToken You need to modify the configuration file available in the mentioned location. The web application that needs to be enabled with form authentication. You need to modify the configuration of your web application to make sure your web application identifies users from the form authentication.   Based on the above, I am going to modify the web configuration. At end of each step, I have mentioned the expected output. I recommend you to go step by step and after each step, make sure the configuration changes are working as expected. If you do everything all together, and test your application at the end, you may face difficulties in troubleshooting the configuration errors. Modifications for Central Administration Web.Config Open the web.config for the Central administration in a text editor. I always prefer Visual Studio, for editing web.config. In most cases, the path of the web.config for the central administration website is as follows C:\inetpub\wwwroot\wss\VirtualDirectories\<port number> Make sure you keep a backup copy of the web.config, before editing it. Let me summarize what we are going to do with Central Administration web.config. First I am going to add a connection string that points to the form authentication database, that I created as mentioned in previous steps. Then I need to add a membership provider and a role manager with the corresponding connectionstring. Then I need to update the peoplepickerwildcards section to make sure the users are appearing in search results. By default there is no connection string available in the web.config of Central Administration. Add a connection string just after the configsections element. The below is the connection string I have used all over the article. <add name="FormAuthConnString" connectionString="Initial Catalog=yourdatabasename;data source=databaseservername;Integrated Security=SSPI;" /> Once you added the connection string, the web.config look similar to Now add membership provider to the code. In web.config for CA, there will be <membership> tag, search for it. You will find membership and role manager under the <system.web> element. Under the membership providers section add the below code… <add name="SPFormAuthMembership" type="System.Web.Security.SqlMembershipProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" applicationName="FormAuthApplication" connectionStringName="FormAuthConnString" /> After adding memberhip element, see the snapshot of the web.config. Now you need to add role manager element to the web.config. Insider providers element under rolemanager, add the below code. <add name="SPFormAuthRoleManager" type="System.Web.Security.SqlRoleProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" applicationName="FormAuthApplication" connectionStringName="FormAuthConnString" /> After adding, your role manager will look similar to the following. As a last step, you need to update the people picker wildcard element in web.config, so that the users from your membership provider are available for browsing in Central Administration. Search for PeoplePickerWildcards in the web.config, add the following inside the <PeoplePickerWildcards> tag. <add key="SPFormAuthMembership" value="%" /> After adding this element, your web.config will look like After completing these steps, you can browse the users available in the SQL server database from central administration website. Go to the site collection administrator’s page from central administration. Select the site collection you have created for form authentication. Click on the people picker icon, choose Forms Auth and click on the search icon, you will see the users listed from the SQL server database. Once you complete these steps, make sure the users are available for browsing from central administration website. If you are unable to find the users, there must be some errors in the configuration, check windows event logs to find related errors and fix them. Change the web.config for STS application Open the web.config for STS application in text editor. By default, STS web.config does not have system.Web or connectionstrings section. Just after the System.Webserver element, add the following code. <connectionStrings> <add name="FormAuthConnString" connectionString="Initial Catalog=aspnetdb_claim;data source=sp2010_db;Integrated Security=SSPI;" /> </connectionStrings> <system.web> <roleManager enabled="true" cacheRolesInCookie="false" cookieName=".ASPXROLES" cookieTimeout="30" cookiePath="/" cookieRequireSSL="false" cookieSlidingExpiration="true" cookieProtection="All" createPersistentCookie="false" maxCachedResults="25"> <providers> <add name="SPFormAuthRoleManager" type="System.Web.Security.SqlRoleProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" applicationName="FormAuthApplication" connectionStringName="FormAuthConnString" /> </providers> </roleManager> <membership userIsOnlineTimeWindow="15" hashAlgorithmType=""> <providers> <add name="SPFormAuthMembership" type="System.Web.Security.SqlMembershipProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" applicationName="FormAuthApplication" connectionStringName="FormAuthConnString" /> </providers> </membership> </system.web> See the snapshot of the web.config after adding the required elements. After adding this, you should be able to login using the credentials from SQL server. Try assigning a user as primary/secondary administrator for your site collection from Central Administration and login to your site using form authentication. If you made everything correct, you should be able to login. This means you have successfully completed configuration of STS Configuration of Web Application for Form Authentication As a last step, you need to modify the web.config of the form authentication web application. Once you have done this, you should be able to grant permissions to users stored in the membership database. Open the Web.config of the web application you created for form authentication. You can find the web.config for the application under the path C:\inetpub\wwwroot\wss\VirtualDirectories\<port number> Basically you need to add connection string, membership provider, role manager and update the people picker wild card configuration. Add the connection string (same as the one you added to the web.config in Central Administration). See the screenshot after the connection string has added. Search for <membership> in the web.config, you will find this inside system.web element. There will be other providers already available there. You add your form authentication membership provider (similar to the one added to Central Administration web.config) to the provider element under membership. Find the snapshot of membership configuration as follows. Search for <roleManager> element in web.config, add the new provider name under providers section of the roleManager element. See the snapshot of web.config after new provider added. Now you need to configure the peoplepickerwildcard configuration in web.config. As I specified earlier, this is to make sure, you can locate the users by entering a part of their username. Add the following line under the <PeoplePickerWildcards> element in web.config. See the screenshot of the peoplePickerWildcards element after the element has been added. Now you have completed all the setup for form authentication. Navigate to the web application. From the site actions -> site settings -> go to peope and groups Click on new -> add users, it will popup the people picker dialog. Click on the icon, select Form Auth, enter a username in the search textbox, and click on search icon. See the screenshot of admin search when I tried searching the users If it displays the user, it means you are done with the configuration. If you add users to the form authentication database, the users will be able to access SharePoint portal as normal.

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  • C#/.NET Fundamentals: Choosing the Right Collection Class

    - by James Michael Hare
    The .NET Base Class Library (BCL) has a wide array of collection classes at your disposal which make it easy to manage collections of objects. While it's great to have so many classes available, it can be daunting to choose the right collection to use for any given situation. As hard as it may be, choosing the right collection can be absolutely key to the performance and maintainability of your application! This post will look at breaking down any confusion between each collection and the situations in which they excel. We will be spending most of our time looking at the System.Collections.Generic namespace, which is the recommended set of collections. The Generic Collections: System.Collections.Generic namespace The generic collections were introduced in .NET 2.0 in the System.Collections.Generic namespace. This is the main body of collections you should tend to focus on first, as they will tend to suit 99% of your needs right up front. It is important to note that the generic collections are unsynchronized. This decision was made for performance reasons because depending on how you are using the collections its completely possible that synchronization may not be required or may be needed on a higher level than simple method-level synchronization. Furthermore, concurrent read access (all writes done at beginning and never again) is always safe, but for concurrent mixed access you should either synchronize the collection or use one of the concurrent collections. So let's look at each of the collections in turn and its various pros and cons, at the end we'll summarize with a table to help make it easier to compare and contrast the different collections. The Associative Collection Classes Associative collections store a value in the collection by providing a key that is used to add/remove/lookup the item. Hence, the container associates the value with the key. These collections are most useful when you need to lookup/manipulate a collection using a key value. For example, if you wanted to look up an order in a collection of orders by an order id, you might have an associative collection where they key is the order id and the value is the order. The Dictionary<TKey,TVale> is probably the most used associative container class. The Dictionary<TKey,TValue> is the fastest class for associative lookups/inserts/deletes because it uses a hash table under the covers. Because the keys are hashed, the key type should correctly implement GetHashCode() and Equals() appropriately or you should provide an external IEqualityComparer to the dictionary on construction. The insert/delete/lookup time of items in the dictionary is amortized constant time - O(1) - which means no matter how big the dictionary gets, the time it takes to find something remains relatively constant. This is highly desirable for high-speed lookups. The only downside is that the dictionary, by nature of using a hash table, is unordered, so you cannot easily traverse the items in a Dictionary in order. The SortedDictionary<TKey,TValue> is similar to the Dictionary<TKey,TValue> in usage but very different in implementation. The SortedDictionary<TKey,TValye> uses a binary tree under the covers to maintain the items in order by the key. As a consequence of sorting, the type used for the key must correctly implement IComparable<TKey> so that the keys can be correctly sorted. The sorted dictionary trades a little bit of lookup time for the ability to maintain the items in order, thus insert/delete/lookup times in a sorted dictionary are logarithmic - O(log n). Generally speaking, with logarithmic time, you can double the size of the collection and it only has to perform one extra comparison to find the item. Use the SortedDictionary<TKey,TValue> when you want fast lookups but also want to be able to maintain the collection in order by the key. The SortedList<TKey,TValue> is the other ordered associative container class in the generic containers. Once again SortedList<TKey,TValue>, like SortedDictionary<TKey,TValue>, uses a key to sort key-value pairs. Unlike SortedDictionary, however, items in a SortedList are stored as an ordered array of items. This means that insertions and deletions are linear - O(n) - because deleting or adding an item may involve shifting all items up or down in the list. Lookup time, however is O(log n) because the SortedList can use a binary search to find any item in the list by its key. So why would you ever want to do this? Well, the answer is that if you are going to load the SortedList up-front, the insertions will be slower, but because array indexing is faster than following object links, lookups are marginally faster than a SortedDictionary. Once again I'd use this in situations where you want fast lookups and want to maintain the collection in order by the key, and where insertions and deletions are rare. The Non-Associative Containers The other container classes are non-associative. They don't use keys to manipulate the collection but rely on the object itself being stored or some other means (such as index) to manipulate the collection. The List<T> is a basic contiguous storage container. Some people may call this a vector or dynamic array. Essentially it is an array of items that grow once its current capacity is exceeded. Because the items are stored contiguously as an array, you can access items in the List<T> by index very quickly. However inserting and removing in the beginning or middle of the List<T> are very costly because you must shift all the items up or down as you delete or insert respectively. However, adding and removing at the end of a List<T> is an amortized constant operation - O(1). Typically List<T> is the standard go-to collection when you don't have any other constraints, and typically we favor a List<T> even over arrays unless we are sure the size will remain absolutely fixed. The LinkedList<T> is a basic implementation of a doubly-linked list. This means that you can add or remove items in the middle of a linked list very quickly (because there's no items to move up or down in contiguous memory), but you also lose the ability to index items by position quickly. Most of the time we tend to favor List<T> over LinkedList<T> unless you are doing a lot of adding and removing from the collection, in which case a LinkedList<T> may make more sense. The HashSet<T> is an unordered collection of unique items. This means that the collection cannot have duplicates and no order is maintained. Logically, this is very similar to having a Dictionary<TKey,TValue> where the TKey and TValue both refer to the same object. This collection is very useful for maintaining a collection of items you wish to check membership against. For example, if you receive an order for a given vendor code, you may want to check to make sure the vendor code belongs to the set of vendor codes you handle. In these cases a HashSet<T> is useful for super-quick lookups where order is not important. Once again, like in Dictionary, the type T should have a valid implementation of GetHashCode() and Equals(), or you should provide an appropriate IEqualityComparer<T> to the HashSet<T> on construction. The SortedSet<T> is to HashSet<T> what the SortedDictionary<TKey,TValue> is to Dictionary<TKey,TValue>. That is, the SortedSet<T> is a binary tree where the key and value are the same object. This once again means that adding/removing/lookups are logarithmic - O(log n) - but you gain the ability to iterate over the items in order. For this collection to be effective, type T must implement IComparable<T> or you need to supply an external IComparer<T>. Finally, the Stack<T> and Queue<T> are two very specific collections that allow you to handle a sequential collection of objects in very specific ways. The Stack<T> is a last-in-first-out (LIFO) container where items are added and removed from the top of the stack. Typically this is useful in situations where you want to stack actions and then be able to undo those actions in reverse order as needed. The Queue<T> on the other hand is a first-in-first-out container which adds items at the end of the queue and removes items from the front. This is useful for situations where you need to process items in the order in which they came, such as a print spooler or waiting lines. So that's the basic collections. Let's summarize what we've learned in a quick reference table.  Collection Ordered? Contiguous Storage? Direct Access? Lookup Efficiency Manipulate Efficiency Notes Dictionary No Yes Via Key Key: O(1) O(1) Best for high performance lookups. SortedDictionary Yes No Via Key Key: O(log n) O(log n) Compromise of Dictionary speed and ordering, uses binary search tree. SortedList Yes Yes Via Key Key: O(log n) O(n) Very similar to SortedDictionary, except tree is implemented in an array, so has faster lookup on preloaded data, but slower loads. List No Yes Via Index Index: O(1) Value: O(n) O(n) Best for smaller lists where direct access required and no ordering. LinkedList No No No Value: O(n) O(1) Best for lists where inserting/deleting in middle is common and no direct access required. HashSet No Yes Via Key Key: O(1) O(1) Unique unordered collection, like a Dictionary except key and value are same object. SortedSet Yes No Via Key Key: O(log n) O(log n) Unique ordered collection, like SortedDictionary except key and value are same object. Stack No Yes Only Top Top: O(1) O(1)* Essentially same as List<T> except only process as LIFO Queue No Yes Only Front Front: O(1) O(1) Essentially same as List<T> except only process as FIFO   The Original Collections: System.Collections namespace The original collection classes are largely considered deprecated by developers and by Microsoft itself. In fact they indicate that for the most part you should always favor the generic or concurrent collections, and only use the original collections when you are dealing with legacy .NET code. Because these collections are out of vogue, let's just briefly mention the original collection and their generic equivalents: ArrayList A dynamic, contiguous collection of objects. Favor the generic collection List<T> instead. Hashtable Associative, unordered collection of key-value pairs of objects. Favor the generic collection Dictionary<TKey,TValue> instead. Queue First-in-first-out (FIFO) collection of objects. Favor the generic collection Queue<T> instead. SortedList Associative, ordered collection of key-value pairs of objects. Favor the generic collection SortedList<T> instead. Stack Last-in-first-out (LIFO) collection of objects. Favor the generic collection Stack<T> instead. In general, the older collections are non-type-safe and in some cases less performant than their generic counterparts. Once again, the only reason you should fall back on these older collections is for backward compatibility with legacy code and libraries only. The Concurrent Collections: System.Collections.Concurrent namespace The concurrent collections are new as of .NET 4.0 and are included in the System.Collections.Concurrent namespace. These collections are optimized for use in situations where multi-threaded read and write access of a collection is desired. The concurrent queue, stack, and dictionary work much as you'd expect. The bag and blocking collection are more unique. Below is the summary of each with a link to a blog post I did on each of them. ConcurrentQueue Thread-safe version of a queue (FIFO). For more information see: C#/.NET Little Wonders: The ConcurrentStack and ConcurrentQueue ConcurrentStack Thread-safe version of a stack (LIFO). For more information see: C#/.NET Little Wonders: The ConcurrentStack and ConcurrentQueue ConcurrentBag Thread-safe unordered collection of objects. Optimized for situations where a thread may be bother reader and writer. For more information see: C#/.NET Little Wonders: The ConcurrentBag and BlockingCollection ConcurrentDictionary Thread-safe version of a dictionary. Optimized for multiple readers (allows multiple readers under same lock). For more information see C#/.NET Little Wonders: The ConcurrentDictionary BlockingCollection Wrapper collection that implement producers & consumers paradigm. Readers can block until items are available to read. Writers can block until space is available to write (if bounded). For more information see C#/.NET Little Wonders: The ConcurrentBag and BlockingCollection Summary The .NET BCL has lots of collections built in to help you store and manipulate collections of data. Understanding how these collections work and knowing in which situations each container is best is one of the key skills necessary to build more performant code. Choosing the wrong collection for the job can make your code much slower or even harder to maintain if you choose one that doesn’t perform as well or otherwise doesn’t exactly fit the situation. Remember to avoid the original collections and stick with the generic collections.  If you need concurrent access, you can use the generic collections if the data is read-only, or consider the concurrent collections for mixed-access if you are running on .NET 4.0 or higher.   Tweet Technorati Tags: C#,.NET,Collecitons,Generic,Concurrent,Dictionary,List,Stack,Queue,SortedList,SortedDictionary,HashSet,SortedSet

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  • How do you manage extensibility in your multi-tenant systems?

    - by Brian MacKay
    I've got a few big web based multi-tenant products now, and very soon I can see that there will be a lot of customizations that are tenant specific. An extra field here or there, maybe an extra page or some extra logic in the middle of a workflow - that sort of thing. Some of these customizations can be rolled into the core product, and that's great. Some of them are highly specific and would get in everyone else's way. I have a few ideas in mind for managing this, but none of them seem to scale well. The obvious solution is to introduce a ton of client-level settings, allowing various 'features' to be enabled on per-client basis. The downside with that, of course, is massive complexity and clutter. You could introduce a truly huge number of settings, and over time various types of logic (presentation, business) could get way out of hand. Then there's the problem of client-specific fields, which begs for something cleaner than just adding a bunch of nullable fields to the existing tables. So what are people doing to manage this? Force.com seems to be the master of extensibility; obviously they've created a platform from the ground up that is super extensible. You can add on to almost anything with their web-based UI. FogBugz did something similiar where they created a robust plugin model that, come to think of it, might have actually been inspired by Force. I know they spent a lot of time and money on it and if I'm not mistaken the intention was to actually use it internally for future product development. Sounds like the kind of thing I could be tempted to build but probably shouldn't. :) Is a massive investment in pluggable architecture the only way to go? How are you managing these problems, and what kind of results are you seeing? EDIT: It does look as though FogBugz handled the problem by building a fairly robust platform and then using that to put together their screens. To extend it you create a DLL containing classes that implement interfaces like ISearchScreenGridColumn, and that becomes a module. I'm sure it was tremendously expensive to build considering that they have a large of devs and they worked on it for months, plus their surface area is perhaps 5% of the size of my application. Right now I am seriously wondering if Force.com is the right way to handle this. And I am a hard core ASP.Net guy, so this is a strange position to find myself in.

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  • How to Enable JavaScript file API in IE8 [closed]

    - by saeed
    i have developed a web application in asp.net , there is a page in this project which user should choose a file in picture format (jpeg,jpg,bmp,...) and i want to preview image in the page but i don't want to post file to server i want to handle it in client i have done it with java scripts functions via file API but it only works in IE9 but most of costumers use IE8 the reason is that IE8 doesn't support file API is there any way to make IE8 upgrade or some patches in code behind i mean that check if the browser is IE and not support file API call a function which upgrades IE8 to IE9 automatically. i don't want to ask user to do it in message i want to do it programmatic !! even if it is possible install a special patch that is required for file API because customers thought it is a bug in my application and their computer knowledge is low what am i supposed to do with this? i also use Async File Upload Ajax Control But it post the file to server any way with ajax solution and http handler but java scripts do it all in client browser!!! following script checks the browser supports API or not <script> if (window.File && window.FileReader && window.FileList && window.Blob) document.write("<b>File API supported.</b>"); else document.write('<i>File API not supported by this browser.</i>'); </script> following scripts do the read and Load Image function readfile(e1) { var filename = e1.target.files[0]; var fr = new FileReader(); fr.onload = readerHandler; fr.readAsText(filename); } HTML code: <input type="file" id="getimage"> <fieldset><legend>Your image here</legend> <div id="imgstore"></div> </fieldset> JavaScript code: <script> function imageHandler(e2) { var store = document.getElementById('imgstore'); store.innerHTML='<img src="' + e2.target.result +'">'; } function loadimage(e1) { var filename = e1.target.files[0]; var fr = new FileReader(); fr.onload = imageHandler; fr.readAsDataURL(filename); } window.onload=function() { var x = document.getElementById("filebrowsed"); x.addEventListener('change', readfile, false); var y = document.getElementById("getimage"); y.addEventListener('change', loadimage, false); } </script>

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  • Wrapping REST based Web Service

    - by PaulPerry
    I am designing a system that will be running online under Microsoft Windows Azure. One component is a REST based web service which will really be a wrapper (using proxy pattern) which calls the REST web services of a business partner, which has to do with BLOB storage (note: we are not using azure storage). The majority of the functionality will be taking a request, calling our partner web service, receiving the request and then passing that back to the client. There are a number of reasons for doing this, but one of the big ones is that we are going to support three clients: our desktop application (win and mac), mobile apps (iOS), and a web front end. Having a single API which we then send to our partner protects us if that partner ever changes. I want our service to support both JSON and XML for the data transfer format, JSON for web and probably XML for the desktop and mobile (we already have an XML parser in those products). Our partner also supports both of these formats. I was planning on using ASP.NET MVC 4 with the Web API. As I design this, the thing that concerns me is the static type checking of C#. What if the partner adds or removes elements from the data? We can probably defensively code for that, but I still feel some concern. Also, we have to do a fair amount of tedious coding, to setup our API and then to turn around and call our partner’s API. There probably is not much choice on it though. But, in the back of my mind I wonder if maybe a more dynamic language would be a better choice. I want to reach out and see if anybody has had to do this before, what technology solutions they have used to (I am not attached to this one, these days Azure can host other technologies), and if anybody who has done something like this can point out any issues that came up. Thanks! Researching the issue seems to only find solutions which focus on connecting a SOAP web service over a proxy server, and not what I am referring to here. Note: Cross posted (by suggestion) from http://stackoverflow.com/questions/11906802/wrapping-rest-based-web-service Thank you!

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