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  • Does this factory method pattern example violate open-close?

    - by William
    In Head-First Design Patterns, they use a pizza shop example to demonstrate the factory method pattern. public abstract class PizzaStore { public Pizza orderPizza(String type) { Pizza pizza; pizza = createPizza(type); pizza.prepare(); pizza.bake(); pizza.cut(); pizza.box(); return pizza; } abstract Pizza createPizza(String type) } public class NYPizzaStore extends PizzaStore { Pizza createPizza(String item) { if (item.equals("cheese") { return new NYStyleCheesePizza(); } else if (item.equals("veggie")) { return new NYStyleVeggiePizza(); } else if (item.equals("clam")) { return new NYStyleClamPizza(); } else if (item.equals("pepperoni")) { return new NYStylePepperioniPizza(); } else return null; } } I don't understand how this pattern is not violating open-close. What if we require a beef Pizza, then we must edit the if statement in the NYPizzaStore class.

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  • WSS V3 and connections to it’s internal database

    - by ptahiliani
    Have you ever wanted to connect to the “Windows Internal” database that WSS V3 uses? While “Windows Internal Database” is Microsoft SQL Server 2005 in a limited edition (just like MSDE, WMSDE before it), the familiar access tools to the DB went missing, and connecting using standard ways doesn’t work either. It doesn’t work right out of the box. First, you need SQL Management Studio Express. Install and start it. Specify the following connection string: \\.\pipe\mssql$microsoft##ssee\sql\query Please note that, as implied by the connection string, this connection only works locally. If you are looking for the connection string than here it is: “Provider=Sqloledb;Data Source=\\.\pipe\MSSQL$MICROSOFT##SSEE\sql\query;Database=SUSDB;Trusted_Connection=yes”

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  • How to get the Dash and HUD to appear. (and stop Unity spewing error messages.)

    - by Ubuntiac
    I just installed Ubuntu 12.04 on my wifes Dell Inspiron 1501, which uses an R300 ATI graphics chip. Neither the Dash or HUD appear when pushing the appropriate key. When I try unity --reset & in the terminal, I see that over and over it's spitting out: r300: CS space validation failed. (not enough memory?) Skipping rendering. This is just after starting Ubuntu with no apps open, so I find it hard to believe that just rendering the Dash / HUD is completely blowing out the VRAM. Any suggestions on getting this working? /usr/lib/nux/unity_support_test -p shows OpenGL vendor string: X.Org R300 Project OpenGL renderer string: Gallium 0.4 on ATI RS480 OpenGL version string: 2.1 Mesa 8.0.2 Not software rendered: yes Not blacklisted: yes GLX fbconfig: yes GLX texture from pixmap: yes GL npot or rect textures: yes GL vertex program: yes GL fragment program: yes GL vertex buffer object: yes GL framebuffer object: yes GL version is 1.4+: yes Unity 3D supported: yes All sections say "YES"

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  • Javascript Tips and Tricks

    - by ybbest
    1. Replace all , in one Javascript string. var totalAmount= "100,000,000,000"; var find= ","; //Replace the first , with the empty string var replace=""; totalAmount= totalAmount.replace(find,replace); alert(totalAmount); var totalAmount2= "100,000,000,000"; var newFind=/,/g //Replace all , with empty string totalAmount2= totalAmount2.replace(newFind,replace); alert(totalAmount2);

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  • How to create Captcha in ASP.NET

    - by Samir R. Bhogayta
    1. Create one page with name "Captcha.aspx" 2. No any control require in this page 3. Go to Captcha.aspx.vb write the below code Protected Sub Page_Load(sender As Object, e As System.EventArgs) Handles Me.Load         'create object of Bitmap Class and set its width and height.         Dim objBMP As Bitmap = New Bitmap(180, 51)         'Create Graphics object and assign bitmap object to graphics' object.         Dim objGraphics As Graphics = Graphics.FromImage(objBMP)         objGraphics.Clear(Color.White)         objGraphics.TextRenderingHint = TextRenderingHint.AntiAlias         Dim objFont As Font = New Font("arial", 30, FontStyle.Bold)         'genetating random 6 digit random number         Dim randomStr As String = GeneratePassword()         'set this random number in session         Session.Add("randomStr", randomStr)         Session.Add("randomStrCountry", randomStr)         objGraphics.DrawString(randomStr, objFont, Brushes.Black, 2, 2)         Response.ContentType = "image/GIF"         objBMP.Save(Response.OutputStream, ImageFormat.Gif)         objFont.Dispose()         objGraphics.Dispose()         objBMP.Dispose()     End Sub     Public Function GeneratePassword() As String         ' Below code describes how to create random numbers.some of the digits and letters         ' are ommited because they look same like "i","o","1","0","I","O".         Dim allowedChars As String = "a,b,c,d,e,f,g,h,j,k,m,n,p,q,r,s,t,u,v,w,x,y,z,"         allowedChars += "A,B,C,D,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,U,V,W,X,Y,Z,"         allowedChars += "2,3,4,5,6,7,8,9"         Dim sep() As Char = {","c}         Dim arr() As String = allowedChars.Split(sep)         Dim passwordString As String = ""         Dim temp As String         Dim rand As Random = New Random()         Dim i As Integer         For i = 0 To 5 - 1 Step i + 1             temp = arr(rand.Next(0, arr.Length))             passwordString += temp         Next         Return passwordString     End Function 4. Use this page in you aspx page like this img alt="" border="0" src="Captcha.aspx" style="cursor: move; height: 60px; width: 200px;" //                                   your textbox to insert code by user.

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  • C# Image Download

    - by Nouman Zakir
    A C# class that makes it easier to download images from the web. Use the following code in your program to download image files such as JPG, GIF, PNG, etc from the internet using WebClient class. using System;using System.Drawing;using System.Drawing.Imaging;using System.IO;using System.Net;public class DownloadImage { private string imageUrl; private Bitmap bitmap; public DownloadImage(string imageUrl) { this.imageUrl = imageUrl; } public void Download() { try { WebClient client = new WebClient(); Stream stream = client.OpenRead(imageUrl); bitmap = new Bitmap(stream); stream.Flush(); stream.Close(); } catch (Exception e) { Console.WriteLine(e.Message); } } public Bitmap GetImage() { return bitmap; } public void SaveImage(string filename, ImageFormat format) { if (bitmap != null) { bitmap.Save(filename, format); } }}

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  • How can I solve display glitches and poor performance with ATI fglrx driver on my ThinkPad X100e?

    - by rewbs
    Hi all, I noticed that video performance on my Thinkpad X100e was very poor compared to Windows 7, so I installed the ATI fglrx proprietary drivers by using the "Additional Drivers" dialogue box. The system has an ATI Radeon Mobility HD 3200 chip. The result of installing the drivers is pretty devastatingly negative, with symptoms such as skewed content in windows, browser tabs and text boxes failing to refresh when their content changes. In fact, please excuse typos in this post, because I can't really see what I am typing. :) I also notice that HD video playback performance is no better - perhaps even worse - than prior to installing the drivers. Example of what I see: Here's the output of fglrxinfo: display: :0.0 screen: 0 OpenGL vendor string: ATI Technologies Inc. OpenGL renderer string: ATI Radeon HD 3200 Graphics OpenGL version string: 3.3.10237 Compatibility Profile Context Output of lspci | grep -i vga: 01:05.0 VGA compatible controller: ATI Technologies Inc RS780M/RS780MN [Radeon HD 3200 Graphics] I'm on Ubuntu 10.10 with kernel 2.6.35-22-generic-pae. What can I try? Many thanks, -R

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  • C# : Parsing information out of a path

    - by mbcrump
    If you have a path for example: \\MyServer\MyFolderA\MyFolderB\MyFile.jpg and you need to parse out the filename, directory name or the directory parent name. You should use the fileinfo class instead of a regex expression or a string split. See the example code below:   Code Snippet using System; using System.IO;   class Test {     static void Main(string[] args)     {         string file = @"\\MyServer\MyFolderA\MyFolderB\MyFile.jpg";         FileInfo fi = new FileInfo(file);         Console.WriteLine(fi.Name);                  // Prints File.jpg         Console.WriteLine(fi.Directory.Name);        // Prints FolderB         Console.WriteLine(fi.Directory.Parent.Name); // Prints FolderA     } }

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  • Local LINQtoSQL Database For Your Windows Phone 7 Application

    - by Tim Murphy
    There aren’t many applications that are of value without having some for of data store.  In Windows Phone development we have a few options.  You can store text directly to isolated storage.  You can also use a number of third party libraries to create or mimic databases in isolated storage.  With Mango we gained the ability to have a native .NET database approach which uses LINQ to SQL.  In this article I will try to bring together the components needed to implement this last type of data store and fill in some of the blanks that I think other articles have left out. Defining A Database The first things you are going to need to do is define classes that represent your tables and a data context class that is used as the overall database definition.  The table class consists of column definitions as you would expect.  They can have relationships and constraints as with any relational DBMS.  Below is an example of a table definition. First you will need to add some assembly references to the code file. using System.ComponentModel;using System.Data.Linq;using System.Data.Linq.Mapping; You can then add the table class and its associated columns.  It needs to implement INotifyPropertyChanged and INotifyPropertyChanging.  Each level of the class needs to be decorated with the attribute appropriate for that part of the definition.  Where the class represents the table the properties represent the columns.  In this example you will see that the column is marked as a primary key and not nullable with a an auto generated value. You will also notice that the in the column property’s set method It uses the NotifyPropertyChanging and NotifyPropertyChanged methods in order to make sure that the proper events are fired. [Table]public class MyTable: INotifyPropertyChanged, INotifyPropertyChanging{ public event PropertyChangedEventHandler PropertyChanged; private void NotifyPropertyChanged(string propertyName) { if(PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } public event PropertyChangingEventHandler PropertyChanging; private void NotifyPropertyChanging(string propertyName) { if(PropertyChanging != null) { PropertyChanging(this, new PropertyChangingEventArgs(propertyName)); } } private int _TableKey; [Column(IsPrimaryKey = true, IsDbGenerated = true, DbType = "INT NOT NULL Identity", CanBeNull = false, AutoSync = AutoSync.OnInsert)] public int TableKey { get { return _TableKey; } set { NotifyPropertyChanging("TableKey"); _TableKey = value; NotifyPropertyChanged("TableKey"); } } The last part of the database definition that needs to be created is the data context.  This is a simple class that takes an isolated storage location connection string its constructor and then instantiates tables as public properties. public class MyDataContext: DataContext{ public MyDataContext(string connectionString): base(connectionString) { MyRecords = this.GetTable<MyTable>(); } public Table<MyTable> MyRecords;} Creating A New Database Instance Now that we have a database definition it is time to create an instance of the data context within our Windows Phone app.  When your app fires up it should check if the database already exists and create an instance if it does not.  I would suggest that this be part of the constructor of your ViewModel. db = new MyDataContext(connectionString);if(!db.DatabaseExists()){ db.CreateDatabase();} The next thing you have to know is how the connection string for isolated storage should be constructed.  The main sticking point I have found is that the database cannot be created unless the file mode is read/write.  You may have different connection strings but the initial one needs to be similar to the following. string connString = "Data Source = 'isostore:/MyApp.sdf'; File Mode = read write"; Using you database Now that you have done all the up front work it is time to put the database to use.  To make your life a little easier and keep proper separation between your view and your viewmodel you should add a couple of methods to the viewmodel.  These will do the CRUD work of your application.  What you will notice is that the SubmitChanges method is the secret sauce in all of the methods that change data. private myDataContext myDb;private ObservableCollection<MyTable> _viewRecords;public ObservableCollection<MyTable> ViewRecords{ get { return _viewRecords; } set { _viewRecords = value; NotifyPropertyChanged("ViewRecords"); }}public void LoadMedstarDbData(){ var tempItems = from MyTable myRecord in myDb.LocalScans select myRecord; ViewRecords = new ObservableCollection<MyTable>(tempItems);}public void SaveChangesToDb(){ myDb.SubmitChanges();}public void AddMyTableItem(MyTable newScan){ myDb.LocalScans.InsertOnSubmit(newScan); myDb.SubmitChanges();}public void DeleteMyTableItem(MyTable newScan){ myDb.LocalScans.DeleteOnSubmit(newScan); myDb.SubmitChanges();} Updating existing database What happens when you need to change the structure of your database?  Unfortunately you have to add code to your application that checks the version of the database which over time will create some pollution in your codes base.  On the other hand it does give you control of the update.  In this example you will see the DatabaseSchemaUpdater in action.  Assuming we added a “Notes” field to the MyTable structure, the following code will check if the database is the latest version and add the field if it isn’t. if(!myDb.DatabaseExists()){ myDb.CreateDatabase();}else{ DatabaseSchemaUpdater dbUdater = myDb.CreateDatabaseSchemaUpdater(); if(dbUdater.DatabaseSchemaVersion < 2) { dbUdater.AddColumn<MyTable>("Notes"); dbUdater.DatabaseSchemaVersion = 2; dbUdater.Execute(); }} Summary This approach does take a fairly large amount of work, but I think the end product is robust and very native for .NET developers.  It turns out to be worth the investment. del.icio.us Tags: Windows Phone,Windows Phone 7,LINQ to SQL,LINQ,Database,Isolated Storage

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  • how do i make maximum minimum and average score statistic in this code? [on hold]

    - by goldensun player
    i wanna out put the maximum minimum and average score as a statistic category under the student ids and grades in the output file. how do i do that? here is the code: #include "stdafx.h" #include <iostream> #include <string> #include <fstream> #include <assert.h> using namespace std; int openfiles(ifstream& infile, ofstream& outfile); void Size(ofstream&, int, string); int main() { int num_student = 4, count, length, score2, w[6]; ifstream infile, curvingfile; char x; ofstream outfile; float score; string key, answer, id; do { openfiles(infile, outfile); // function calling infile >> key; // answer key for (int i = 0; i < num_student; i++) // loop over each student { infile >> id; infile >> answer; count = 0; length = key.size(); // length represents number of questions in exam from exam1.dat // size is a string function.... Size (outfile, length, answer); for (int j = 0; j < length; j++) // loop over each question { if (key[j] == answer[j]) count++; } score = (float) count / length; score2 = (int)(score * 100); outfile << id << " " << score2 << "%"; if (score2 >= 90)//<-----w[0] outfile << "A" << endl; else if (score2 >= 80)//<-----w[1] outfile << "B" << endl; else if (score2 >= 70)//<-----w[2] outfile << "C" << endl; else if (score2 >= 60)//<-----w[3] outfile << "D" << endl; else if (score2 >= 50)//<-----w[4] outfile << "E" << endl; else if (score2 < 50)//<-----w[5] outfile << "F" << endl; } cout << "Would you like to attempt a new trial? (y/n): "; cin >> x; } while (x == 'y' || x == 'Y'); return 0; } int openfiles(ifstream& infile, ofstream& outfile) { string name1, name2, name3, answerstring, curvedata; cin >> name1; name2; name3; if (name1 == "exit" || name2 == "exit" || name3 == "exit" ) return false; cout << "Input the name for the exam file: "; cin >> name1; infile.open(name1.c_str()); infile >> answerstring; cout << "Input the name for the curving file: "; cin >> name2; infile.open(name2.c_str()); infile >> curvedata; cout << "Input the name for the output: "; cin >> name3; outfile.open(name3.c_str()); return true; } void Size(ofstream& outfile, int length, string answer) { bool check;// extra answers, lesser answers... if (answer.size() > length) { outfile << "Unnecessary extra answers"; } else if (answer.size() < length) { outfile << "The remaining answers are incorrect"; } else { check = false; }; } and how do i use assert for preconditions and post conditional functions? i dont understand this that well...

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  • Javascript Tips and Tricks

    - by ybbest
    1. Replace all , in one Javascript string. var totalAmount= "100,000,000,000"; var find= ","; //Replace the first , with the empty string var replace=""; totalAmount= totalAmount.replace(find,replace); alert(totalAmount); var totalAmount2= "100,000,000,000"; var newFind=/,/g //Replace all , with empty string totalAmount2= totalAmount2.replace(newFind,replace); alert(totalAmount2);

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  • Why am I stuck at 640x480 on an Optimus hybrid-graphics system?

    - by exilada
    I have Intel HD 3000 graphics card onboard and nvidia 520 mx optimus techolonogy card. I was try to install Nvidia driver but it was failure. Now I cant use anything. Have one resolution 640x480 every media disconnected and I cant connect $ xrandr Screen 0: minimum 320 x 200, current 640 x 480, maximum 8192 x 8192 LVDS1 connected 640x480+0+0 (normal left inverted right x axis y axis) 344mm x 194mm 640x480 59.9* VGA1 disconnected (normal left inverted right x axis y axis) HDMI1 disconnected (normal left inverted right x axis y axis) DP1 disconnected (normal left inverted right x axis y axis) lspci | grep VGA 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09 ) glxinfo | grep vendor server glx vendor string: SGI client glx vendor string: Mesa Project and SGI OpenGL vendor string: Tungsten Graphics, Inc Blockquote something wrong here I guess I try to some solutions but didnt work even it cant nvidia-xconfig file after these By the way system get eror sometimes about xorg Sorry for my English thaks for help.

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  • When and How is an image cached for an ASPX with ContentType = image/jpeg ?

    - by Aamir Hasan
     In asp.net you can cache your page. You can vary the output cache by the followingThe query string in an initial request (HTTP GET).Control values passed on postback (HTTP POST values).The HTTP headers passed with a request.The major version number of the browser making the request.      A custom string in the page. In that case, you create custom code in the Global.asax file to specify the page's caching behavior.Link: http://msdn2.microsoft.com/en-us/library/xadzbzd6(VS.80).aspxyou can set the output caching for your GetImage.aspx, so that you dont have to requery the database every image request ,but you must use varybyParam , so that you have a cached version for every parameters arrangement:set the output cache for your page like this :At top of ASPX page: <%@ OutputCache Duration="600" VaryByParam="ID,Height,Width" %>VaryByParam  attribute allows you to vary the cached output depending on the query string.Adding this will make your images cached for 600 seconds, so that if the image request within this period ,the cahed version will be returned

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  • Using "Google Guava" in coding interviews

    - by kbgn27
    I attended a in-person interview recently and performed well. But surprisingly I got rejected. When I asked the HR for reason, he contacted the technical interviewer and told me that I was syntactically wrong while coding. I used Google Guava for coding. So my code looked like this: List<String> items = Lists.newArrayList() instead of List<String> items =new ArrayList<String>(); I know that the code will compile and work as expected.Is it ok to use third party libraries like Google Guava in interviews?

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  • screen driver problem

    - by exilada
    I have Intel HD 3000 graphics card onboard and nvidia 520 mx optimus techolonogy card. I was try to install Nvidia driver but it was failure. Now I cant use anything. Have one resolution 640x480 every media disconnected and I cant connect $ xrandr Screen 0: minimum 320 x 200, current 640 x 480, maximum 8192 x 8192 LVDS1 connected 640x480+0+0 (normal left inverted right x axis y axis) 344mm x 194mm 640x480 59.9* VGA1 disconnected (normal left inverted right x axis y axis) HDMI1 disconnected (normal left inverted right x axis y axis) DP1 disconnected (normal left inverted right x axis y axis) lspci | grep VGA 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09 ) glxinfo | grep vendor server glx vendor string: SGI client glx vendor string: Mesa Project and SGI OpenGL vendor string: Tungsten Graphics, Inc Blockquote something wrong here I guess I try to some solutions but didnt work even it cant nvidia-xconfig file after these By the way system get eror sometimes about xorg Sorry for my English thaks for help.

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  • Returning status code where one of many errors could have occured

    - by yttriuszzerbus
    I'm developing a PHP login component which includes functions to manipulate the User object, such as $User->changePassword(string $old, string $new) What I need some advice with is how to return a status, as the function can either succeed (no further information needs to be given) or fail (and the calling code needs to know why, for example incorrect password, database problem etc.) I've come up with the following ideas: Unix-style: return 0 on success, another code on failure. This doesn't seem particularly common in PHP and the language's type-coercion messes with this (a function returning FALSE on success?) This seems to be the best I can think of. Throw an exception on error. PHP's exception support is limited, and this will make life harder for anybody trying to use the functions. Return an array, containing a boolean for "success" or not, and a string or an int for "failure status" if applicable. None of these seem particularly appealing, does anyone have any advice or better ideas?

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  • DRIconf in Ubuntu 64x plus ATI GPU or something more?

    - by Balask
    I've been trying to get Call of Duty 2 to work in Wine in Ubuntu. It gives me a black screen. So I tried the fix suggested by the wine apphq and downloaded DRIconf. Funny thing is that it can't find my direct rendering device. "Could not detect any configurable direct-rendering capable devices. DRIconf will be started in expert mode" When I enter into it in Expert Mode is just errors out anyway. fglrxinfo gives me: display: :0 screen: 0 OpenGL vendor string: Advanced Micro Devices, Inc. OpenGL renderer string: ATI Mobility Radeon HD 4200 Series OpenGL version string: 3.3.11627 Compatibility Profile Context That shows me my driver is installed correctl,y right? World of Goo which is Linux native and requires direct rendering works like a charm. So I'm wondering, is there some other workaround? Is there a bigger issue? Does me running 64-bit affect it at all?

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  • Android app, No error message but has stopped unexpectedly [migrated]

    - by user74722
    Does anyone know what is my problem. I do not have any compile error messages however when i run the app it crashes and stops unexpectedly. Here is my codes. Thank you in advance. ListView l ; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_final_project); String arr[]={"Red","Green","Blue","Yellow","Cyan"}; l=(ListView) findViewById(R.id.listView1); ArrayAdapter<String> adapter=new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, arr); l.setAdapter(adapter); Button buttonOne = (Button) findViewById(R.id.button1); buttonOne.setOnClickListener(new OnClickListener(){ @Override public void onClick(View v){ setContentView(R.layout.layout_save); // setContentView(R.layout.activity_final_project); //startActivity(new Intent("com.example.finalproject.layout_save")); } }); }

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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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  • CodePlex Daily Summary for Tuesday, January 11, 2011

    CodePlex Daily Summary for Tuesday, January 11, 2011Popular ReleasesArcGIS Editor for OpenStreetMap: ArcGIS Editor for OpenStreetMap 1.1 beta2: This is the beta2 release for the ArcGIS Editor for OpenStreetMap version 1.1. Changes from version 1.0: Multi-part geometries are now supported. Homogeneous relations (consisting of only lines or only polygons) are converted into the appropriate multi-part geometry. Mixed relations and super relations are maintained and tracked in a stand-alone relation table. The underlying editing logic has changed. As opposed to tracking the editing changes upon "Save edit" or "Stop edit" the changes a...VSSpeedster - Parallel Builds for VS: VSSpeedster 1.2 (beta): - Improved Parallel Builds - Cancel running Parallel Build using Ctrl+BreakASP.NET Comet Ajax Library (Reverse Ajax - Server Push): Multiple server ASP.NET Reverse Ajax: This sample project demonstrates how is easy to scale your web applications via PokeInHawkeye - The .Net Runtime Object Editor: Hawkeye 1.2.5: In the case you are running an x86 Windows and you installed Release 1.2.4, you should consider upgrading to this release (1.2.5) as it appears Hawkeye is broken on x86 OS. I apologize for the inconvenience, but it appears Hawkeye 1.2.4 (and probably previous versions) doesn't run on x86 Windows (See issue http://hawkeye.codeplex.com/workitem/7791). This maintenance release fixes this broken behavior. This release comes in two flavors: Hawkeye.125.N2 is the standard .NET 2 build, was compile...Phalanger - The PHP Language Compiler for the .NET Framework: 2.0 (January 2011): Another release build for daily use; it contains many new features, enhanced compatibility with latest PHP opensource applications and several issue fixes. To improve the performance of your application using MySQL, please use Managed MySQL Extension for Phalanger. Changes made within this release include following: New features available only in Phalanger. Full support of Multi-Script-Assemblies was implemented; you can build your application into several DLLs now. Deploy them separately t...EnhSim: EnhSim 2.3.0: 2.3.0This release supports WoW patch 4.03a at level 85 To use this release, you must have the Microsoft Visual C++ 2010 Redistributable Package installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=A7B7A05E-6DE6-4D3A-A423-37BF0912DB84 To use the GUI you must have the .NET 4.0 Framework installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=9cfb2d51-5ff4-4491-b0e5-b386f32c0992 - Changed how flame shoc...AutoLoL: AutoLoL v1.5.3: A message will be displayed when there's an update available Shows a list of recent mastery files in the Editor Tab (requested by quite a few people) Updater: Update information is now scrollable Added a buton to launch AutoLoL after updating is finished Updated the UI to match that of AutoLoL Fix: Detects and resolves 'Read Only' state on Version.xmlExtended WPF Toolkit: Extended WPF Toolkit - 1.3.0: What's in the 1.3.0 Release?BusyIndicator ButtonSpinner ChildWindow ColorPicker - Updated (Breaking Changes) DateTimeUpDown - New Control Magnifier - New Control MaskedTextBox - New Control MessageBox NumericUpDown RichTextBox RichTextBoxFormatBar - Updated .NET 3.5 binaries and SourcePlease note: The Extended WPF Toolkit 3.5 is dependent on .NET Framework 3.5 and the WPFToolkit. You must install .NET Framework 3.5 and the WPFToolkit in order to use any features in the To...sNPCedit: sNPCedit v0.9d: added elementclient coordinate catcher to catch coordinates select a target (ingame) i.e. your char, npc or monster than click the button and coordinates+direction will be transfered to the selected row in the table corrected labels from Rot to Direction (because it is a vector)Free Silverlight & WPF Chart Control - Visifire: Visifire SL and WPF Charts v3.6.7 beta Released: Hi, Today Visifire is released along with one new feature * Inlines property has been implemented in Title. Now onwards you can customize the text content in Title. Please check out the Visifire documentation for more information. This release contains fix for the following bugs: * Styles for chart elements were not working as expected. * Bar chart was not drawn properly if AxisMinimum property was set to a value above zero base line. * In DateTime axis, AxisLables were no...Ionics Isapi Rewrite Filter: 2.1 latest stable: V2.1 is stable, and is in maintenance mode. This is v2.1.1.25. It is a bug-fix release. There are no new features. 28629 29172 28722 27626 28074 29164 27659 27900 many documentation updates and fixes proper x64 build environment. This release includes x64 binaries in zip form, but no x64 MSI file. You'll have to manually install x64 servers, following the instructions in the documentation.StyleCop for ReSharper: StyleCop for ReSharper 5.1.14980.000: A considerable amount of work has gone into this release: Huge focus on performance around the violation scanning subsystem: - caching added to reduce IO operations around reading and merging of settings files - caching added to reduce creation of expensive objects Users should notice condsiderable perf boost and a decrease in memory usage. Bug Fixes: - StyleCop's new ObjectBasedEnvironment object does not resolve the StyleCop installation path, thus it does not return the correct path ...VivoSocial: VivoSocial 7.4.1: New release with bug fixes and updates for performance.UltimateJB: Ultimate JB 2.03 PL3 KAKAROTO + HERMES + Spoof 3.5: Voici une version attendu avec impatience pour beaucoup : - La version PL3 KAKAROTO intégre ses dernières modification et intégre maintenant le firmware 2.43 !!! Conclusion : - UltimateJB203PSXXXDEFAULTKAKAROTO=> Pas de spoof mais disponible pour les PS3 suivantes : 3.41_kiosk 3.41 3.40 3.30 3.21 3.15 3.10 3.01 2.76 2.70 2.60 2.53 2.43 - UltimateJB203PS341_HERMES => Pas de spoof mais version hermes 4b - UltimateJB203PS341HERMESSPOOF35X => hermes 4b + spoof des firmwares 3.50 et 3.55 au li....NET Extensions - Extension Methods Library for C# and VB.NET: Release 2011.03: Added lot's of new extensions and new projects for MVC and Entity Framework. object.FindTypeByRecursion Int32.InRange String.RemoveAllSpecialCharacters String.IsEmptyOrWhiteSpace String.IsNotEmptyOrWhiteSpace String.IfEmptyOrWhiteSpace String.ToUpperFirstLetter String.GetBytes String.ToTitleCase String.ToPlural DateTime.GetDaysInYear DateTime.GetPeriodOfDay IEnumberable.RemoveAll IEnumberable.Distinct ICollection.RemoveAll IList.Join IList.Match IList.Cast Array.IsNullOrEmpty Array.W...EFMVC - ASP.NET MVC 3 and EF Code First: EFMVC 0.5- ASP.NET MVC 3 and EF Code First: Demo web app ASP.NET MVC 3, Razor and EF Code FirstVidCoder: 0.8.0: Added x64 version. Made the audio output preview more detailed and accurate. If the chosen encoder or mixdown is incompatible with the source, the fallback that will be used is displayed. Added "Auto" to the audio mixdown choices. Reworked non-anamorphic size calculation to work better with non-standard pixel aspect ratios and cropping. Reworked Custom anamorphic to be more intuitive and allow display width to be set automatically (Thanks, Statick). Allowing higher bitrates for 6-ch....NET Voice Recorder: Auto-Tune Release: This is the source code and binaries to accompany the article on the Coding 4 Fun website. It is the Auto Tuner release of the .NET Voice Recorder application.BloodSim: BloodSim - 1.3.2.0: - Simulation Log is now automatically disabled and hidden when running 10 or more iterations - Hit and Expertise are now entered by Rating, and include option for a Racial Expertise bonus - Added option for boss to use a periodic magic ability (Dragon Breath) - Added option for boss to periodically Enrage, gaining a Damage/Attack Speed buffASP.NET MVC CMS ( Using CommonLibrary.NET ): CommonLibrary.NET CMS 0.9.5 Alpha: CommonLibrary CMSA simple yet powerful CMS system in ASP.NET MVC 2 using C# 4.0. ActiveRecord based components for Blogs, Widgets, Pages, Parts, Events, Feedback, BlogRolls, Links Includes several widgets ( tag cloud, archives, recent, user cloud, links twitter, blog roll and more ) Built using the http://commonlibrarynet.codeplex.com framework. ( Uses TDD, DDD, Models/Entities, Code Generation ) Can run w/ In-Memory Repositories or Sql Server Database See Documentation tab for Ins...New Projects.NET Event Spy: Full information available here: http://martincarolan.blogspot.com/2011/01/secret-project.html Simple development/debugging tool that hooks into and monitors events raised on any .NET object3DTweet: 3Dtweet is an effort to make tweets appear in a aesthetic manner to the users of windows phone.Its developed using VS2010 expresss.Agile .NET with SCRUM and XP: Source code for the book Apress Professional Agile .NET Development with SCRUM and XPBeskid Niski Agroturystyka: Travel Poland, turystyka w beskidzie niskim. Agroturystyka w miejscowosci Losie nad zalewem KlimkowkaCoding better: A better coding labs for .net new feature.FBApp: A simple facebook app I was busy with over the holidays as an experiment to try out the facebook api. Is currently not complete but I wanted to get some criticism on it for my 1st web app. It is developed using WPF and C#. Freemium Helper for WebMatrix: The Freemium Helper for WebMatrix provides an easy way to apply the Freemium model into your WebMatrix site. Using different user groups (or roles), it allows you to easily enable or disable features on your pages depending on the stock-keeping unit the user has paid for.Haversine Distance Calculation: A very small project that implements the Haversine formula, which calculates the great circle distance between two points on the earth's surface. The points are latitude / longitude coordinates in DD. The formula is implemented client side with javascript and server side with C#.Hexa.Core: Hexa.Core is our implementation of the Domain Driven Design Architecture. Also providing a set of helper classes for ASP.Net and WCF development.Minecraft NBT reader: A simple Minecraft NBT reader.MobSoft: MobSoft is silverlight based news related application designed to test the new functionalitities in Silverlight 4netduino Helpers: The 'netduino Helpers' is a C# driver set for common hardware components and features convenient wrappers around complex .Net Micro Framework features such as: Analog joysticks, Real-time clock, 8*8 LED matrix, Shift register, runtime assembly & resource loader, bitmaps, etc.NewsGator Social Connectors for Sharepoint 2010: This project contains social connectors for the NewsGator SharePoint platform and supports sending messages to Twitter and LinkedIn just by putting tags in the text #li for sending to linkedin #tw for sending to twitterNon Profit Contact Relationship Management: A non profit contact relationship management software intended to help those in the non profit arena manage donors, sponsors, and prospects.OpenAGE: OpenAGE, short for Open Advance Game Engine, is aimed at developing a new Advanced Game engine strictly for the PC and Xbox360 gaming System using XNA 4.0, and Visual Studio 2010OpenAutoPoster: OpenAutoPoster automates some of the boring everyday tasks of aggregating, linking and posting that haunts content creators.Phefer WoodTurning Sketcher: Draw out your own turnings before you hit the wood. Import images and trace around them, print them out with the length and width measuresments.Simple Script Interpreter- A simple GPLEX/GPPG (Lex/Yacc) Primer: Simple Script is a simple implementation of an interpreter language built with GPlex and Gppg (Lex/Yacc). It's developed in C#.SP2010Tutorials: Code for learning SharePoint 2010The Social Developer: This is a social developer tool for programmers to create and share projects using the .Net framework and other technologies and integrate it into a socialistic approach of sharing the work load and the resources needed to develop high level applications. Traffic-sign Classification: Traffic sign shape classification and localization.unnamedyet: Experimental! para Investigadores de Sistemas. Objetivo! desarrollar una praxis tal que con un conjunto finito y discreto de términos para describir sea posible auto-demostrar y ejecutar cualquier proposición dada.VSSpeedster - Parallel Builds for VS: Improve the performance of your Visual Studio: - Parallel Builds integrated in visual studioWebservice Xslt Transformer WebPart for SharePoint 2010: The Dynamic Webservice Xslt Transformer WebPart makes it much easier for SharePoint Developers and Administrators to call the webservice and transform the results directly to HTML by providing their own custom xslt. The properties can be set on the webpart by using the UI.WilWaNet.HASH: An ASP.NET MVC web site designed for tracking nutrition for the purposes of losing weight. Tracks calories, fat calories, fat grams and saturated fat along with daily weight and exercise. Includes daily Basic Metabolic Rate calculation and graphing functions.WP7 Try it 01: The first try in wp7WPF TryIt 01: Quan ly Nhan khau WPF ApplicationWX Alerter CAP/XML: NWS Alerter using CAP 1.1 alerting protocol. The goal of this project is to consume weather alerts from the NWS site. The user will select the city or SAME code/zone to watch. As alerts trigger notices will display and info will fill the Alert Tab.

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  • ASP.NET MVC 3 Hosting :: How to Deploy Web Apps Using ASP.NET MVC 3, Razor and EF Code First - Part I

    - by mbridge
    First, you can download the source code from http://efmvc.codeplex.com. The following frameworks will be used for this step by step tutorial. public class Category {     public int CategoryId { get; set; }     [Required(ErrorMessage = "Name Required")]     [StringLength(25, ErrorMessage = "Must be less than 25 characters")]     public string Name { get; set;}     public string Description { get; set; }     public virtual ICollection<Expense> Expenses { get; set; } } Expense Class public class Expense {             public int ExpenseId { get; set; }            public string  Transaction { get; set; }     public DateTime Date { get; set; }     public double Amount { get; set; }     public int CategoryId { get; set; }     public virtual Category Category { get; set; } }    Define Domain Model Let’s create domain model for our simple web application Category Class We have two domain entities - Category and Expense. A single category contains a list of expense transactions and every expense transaction should have a Category. In this post, we will be focusing on CRUD operations for the entity Category and will be working on the Expense entity with a View Model object in the later post. And the source code for this application will be refactored over time. The above entities are very simple POCO (Plain Old CLR Object) classes and the entity Category is decorated with validation attributes in the System.ComponentModel.DataAnnotations namespace. Now we want to use these entities for defining model objects for the Entity Framework 4. Using the Code First approach of Entity Framework, we can first define the entities by simply writing POCO classes without any coupling with any API or database library. This approach lets you focus on domain model which will enable Domain-Driven Development for applications. EF code first support is currently enabled with a separate API that is runs on top of the Entity Framework 4. EF Code First is reached CTP 5 when I am writing this article. Creating Context Class for Entity Framework We have created our domain model and let’s create a class in order to working with Entity Framework Code First. For this, you have to download EF Code First CTP 5 and add reference to the assembly EntitFramework.dll. You can also use NuGet to download add reference to EEF Code First. public class MyFinanceContext : DbContext {     public MyFinanceContext() : base("MyFinance") { }     public DbSet<Category> Categories { get; set; }     public DbSet<Expense> Expenses { get; set; }         }   The above class MyFinanceContext is derived from DbContext that can connect your model classes to a database. The MyFinanceContext class is mapping our Category and Expense class into database tables Categories and Expenses using DbSet<TEntity> where TEntity is any POCO class. When we are running the application at first time, it will automatically create the database. EF code-first look for a connection string in web.config or app.config that has the same name as the dbcontext class. If it is not find any connection string with the convention, it will automatically create database in local SQL Express database by default and the name of the database will be same name as the dbcontext class. You can also define the name of database in constructor of the the dbcontext class. Unlike NHibernate, we don’t have to use any XML based mapping files or Fluent interface for mapping between our model and database. The model classes of Code First are working on the basis of conventions and we can also use a fluent API to refine our model. The convention for primary key is ‘Id’ or ‘<class name>Id’.  If primary key properties are detected with type ‘int’, ‘long’ or ‘short’, they will automatically registered as identity columns in the database by default. Primary key detection is not case sensitive. We can define our model classes with validation attributes in the System.ComponentModel.DataAnnotations namespace and it automatically enforces validation rules when a model object is updated or saved. Generic Repository for EF Code First We have created model classes and dbcontext class. Now we have to create generic repository pattern for data persistence with EF code first. If you don’t know about the repository pattern, checkout Martin Fowler’s article on Repository Let’s create a generic repository to working with DbContext and DbSet generics. public interface IRepository<T> where T : class     {         void Add(T entity);         void Delete(T entity);         T GetById(long Id);         IEnumerable<T> All();     } RepositoryBasse – Generic Repository class protected MyFinanceContext Database {     get { return database ?? (database = DatabaseFactory.Get()); } } public virtual void Add(T entity) {     dbset.Add(entity);            }        public virtual void Delete(T entity) {     dbset.Remove(entity); }   public virtual T GetById(long id) {     return dbset.Find(id); }   public virtual IEnumerable<T> All() {     return dbset.ToList(); } } DatabaseFactory class public class DatabaseFactory : Disposable, IDatabaseFactory {     private MyFinanceContext database;     public MyFinanceContext Get()     {         return database ?? (database = new MyFinanceContext());     }     protected override void DisposeCore()     {         if (database != null)             database.Dispose();     } } Unit of Work If you are new to Unit of Work pattern, checkout Fowler’s article on Unit of Work . According to Martin Fowler, the Unit of Work pattern "maintains a list of objects affected by a business transaction and coordinates the writing out of changes and the resolution of concurrency problems." Let’s create a class for handling Unit of Work public interface IUnitOfWork {     void Commit(); } UniOfWork class public class UnitOfWork : IUnitOfWork {     private readonly IDatabaseFactory databaseFactory;     private MyFinanceContext dataContext;       public UnitOfWork(IDatabaseFactory databaseFactory)     {         this.databaseFactory = databaseFactory;     }       protected MyFinanceContext DataContext     {         get { return dataContext ?? (dataContext = databaseFactory.Get()); }     }       public void Commit()     {         DataContext.Commit();     } } The Commit method of the UnitOfWork will call the commit method of MyFinanceContext class and it will execute the SaveChanges method of DbContext class.   Repository class for Category In this post, we will be focusing on the persistence against Category entity and will working on other entities in later post. Let’s create a repository for handling CRUD operations for Category using derive from a generic Repository RepositoryBase<T>. public class CategoryRepository: RepositoryBase<Category>, ICategoryRepository     {     public CategoryRepository(IDatabaseFactory databaseFactory)         : base(databaseFactory)         {         }                } public interface ICategoryRepository : IRepository<Category> { } If we need additional methods than generic repository for the Category, we can define in the CategoryRepository. Dependency Injection using Unity 2.0 If you are new to Inversion of Control/ Dependency Injection or Unity, please have a look on my articles at http://weblogs.asp.net/shijuvarghese/archive/tags/IoC/default.aspx. I want to create a custom lifetime manager for Unity to store container in the current HttpContext. public class HttpContextLifetimeManager<T> : LifetimeManager, IDisposable {     public override object GetValue()     {         return HttpContext.Current.Items[typeof(T).AssemblyQualifiedName];     }     public override void RemoveValue()     {         HttpContext.Current.Items.Remove(typeof(T).AssemblyQualifiedName);     }     public override void SetValue(object newValue)     {         HttpContext.Current.Items[typeof(T).AssemblyQualifiedName] = newValue;     }     public void Dispose()     {         RemoveValue();     } } Let’s create controller factory for Unity in the ASP.NET MVC 3 application.                 404, String.Format(                     "The controller for path '{0}' could not be found" +     "or it does not implement IController.",                 reqContext.HttpContext.Request.Path));       if (!typeof(IController).IsAssignableFrom(controllerType))         throw new ArgumentException(                 string.Format(                     "Type requested is not a controller: {0}",                     controllerType.Name),                     "controllerType");     try     {         controller= container.Resolve(controllerType) as IController;     }     catch (Exception ex)     {         throw new InvalidOperationException(String.Format(                                 "Error resolving controller {0}",                                 controllerType.Name), ex);     }     return controller; }   } Configure contract and concrete types in Unity Let’s configure our contract and concrete types in Unity for resolving our dependencies. private void ConfigureUnity() {     //Create UnityContainer               IUnityContainer container = new UnityContainer()                 .RegisterType<IDatabaseFactory, DatabaseFactory>(new HttpContextLifetimeManager<IDatabaseFactory>())     .RegisterType<IUnitOfWork, UnitOfWork>(new HttpContextLifetimeManager<IUnitOfWork>())     .RegisterType<ICategoryRepository, CategoryRepository>(new HttpContextLifetimeManager<ICategoryRepository>());                 //Set container for Controller Factory                ControllerBuilder.Current.SetControllerFactory(             new UnityControllerFactory(container)); } In the above ConfigureUnity method, we are registering our types onto Unity container with custom lifetime manager HttpContextLifetimeManager. Let’s call ConfigureUnity method in the Global.asax.cs for set controller factory for Unity and configuring the types with Unity. protected void Application_Start() {     AreaRegistration.RegisterAllAreas();     RegisterGlobalFilters(GlobalFilters.Filters);     RegisterRoutes(RouteTable.Routes);     ConfigureUnity(); } Developing web application using ASP.NET MVC 3 We have created our domain model for our web application and also have created repositories and configured dependencies with Unity container. Now we have to create controller classes and views for doing CRUD operations against the Category entity. Let’s create controller class for Category Category Controller public class CategoryController : Controller {     private readonly ICategoryRepository categoryRepository;     private readonly IUnitOfWork unitOfWork;           public CategoryController(ICategoryRepository categoryRepository, IUnitOfWork unitOfWork)     {         this.categoryRepository = categoryRepository;         this.unitOfWork = unitOfWork;     }       public ActionResult Index()     {         var categories = categoryRepository.All();         return View(categories);     }     [HttpGet]     public ActionResult Edit(int id)     {         var category = categoryRepository.GetById(id);         return View(category);     }       [HttpPost]     public ActionResult Edit(int id, FormCollection collection)     {         var category = categoryRepository.GetById(id);         if (TryUpdateModel(category))         {             unitOfWork.Commit();             return RedirectToAction("Index");         }         else return View(category);                 }       [HttpGet]     public ActionResult Create()     {         var category = new Category();         return View(category);     }           [HttpPost]     public ActionResult Create(Category category)     {         if (!ModelState.IsValid)         {             return View("Create", category);         }                     categoryRepository.Add(category);         unitOfWork.Commit();         return RedirectToAction("Index");     }       [HttpPost]     public ActionResult Delete(int  id)     {         var category = categoryRepository.GetById(id);         categoryRepository.Delete(category);         unitOfWork.Commit();         var categories = categoryRepository.All();         return PartialView("CategoryList", categories);       }        } Creating Views in Razor Now we are going to create views in Razor for our ASP.NET MVC 3 application.  Let’s create a partial view CategoryList.cshtml for listing category information and providing link for Edit and Delete operations. CategoryList.cshtml @using MyFinance.Helpers; @using MyFinance.Domain; @model IEnumerable<Category>      <table>         <tr>         <th>Actions</th>         <th>Name</th>          <th>Description</th>         </tr>     @foreach (var item in Model) {             <tr>             <td>                 @Html.ActionLink("Edit", "Edit",new { id = item.CategoryId })                 @Ajax.ActionLink("Delete", "Delete", new { id = item.CategoryId }, new AjaxOptions { Confirm = "Delete Expense?", HttpMethod = "Post", UpdateTargetId = "divCategoryList" })                           </td>             <td>                 @item.Name             </td>             <td>                 @item.Description             </td>         </tr>         }       </table>     <p>         @Html.ActionLink("Create New", "Create")     </p> The delete link is providing Ajax functionality using the Ajax.ActionLink. This will call an Ajax request for Delete action method in the CategoryCotroller class. In the Delete action method, it will return Partial View CategoryList after deleting the record. We are using CategoryList view for the Ajax functionality and also for Index view using for displaying list of category information. Let’s create Index view using partial view CategoryList  Index.chtml @model IEnumerable<MyFinance.Domain.Category> @{     ViewBag.Title = "Index"; }    <h2>Category List</h2>    <script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.min.js")" type="text/javascript"></script>    <div id="divCategoryList">               @Html.Partial("CategoryList", Model) </div> We can call the partial views using Html.Partial helper method. Now we are going to create View pages for insert and update functionality for the Category. Both view pages are sharing common user interface for entering the category information. So I want to create an EditorTemplate for the Category information. We have to create the EditorTemplate with the same name of entity object so that we can refer it on view pages using @Html.EditorFor(model => model) . So let’s create template with name Category. Category.cshtml @model MyFinance.Domain.Category <div class="editor-label"> @Html.LabelFor(model => model.Name) </div> <div class="editor-field"> @Html.EditorFor(model => model.Name) @Html.ValidationMessageFor(model => model.Name) </div> <div class="editor-label"> @Html.LabelFor(model => model.Description) </div> <div class="editor-field"> @Html.EditorFor(model => model.Description) @Html.ValidationMessageFor(model => model.Description) </div> Let’s create view page for insert Category information @model MyFinance.Domain.Category   @{     ViewBag.Title = "Save"; }   <h2>Create</h2>   <script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script>   @using (Html.BeginForm()) {     @Html.ValidationSummary(true)     <fieldset>         <legend>Category</legend>                @Html.EditorFor(model => model)               <p>             <input type="submit" value="Create" />         </p>     </fieldset> }   <div>     @Html.ActionLink("Back to List", "Index") </div> ViewStart file In Razor views, we can add a file named _viewstart.cshtml in the views directory  and this will be shared among the all views with in the Views directory. The below code in the _viewstart.cshtml, sets the Layout page for every Views in the Views folder.     @{     Layout = "~/Views/Shared/_Layout.cshtml"; } Tomorrow, we will cotinue the second part of this article. :)

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  • Developing web apps using ASP.NET MVC 3, Razor and EF Code First - Part 2

    - by shiju
    In my previous post Developing web apps using ASP.NET MVC 3, Razor and EF Code First - Part 1, we have discussed on how to work with ASP.NET MVC 3 and EF Code First for developing web apps. We have created generic repository and unit of work with EF Code First for our ASP.NET MVC 3 application and did basic CRUD operations against a simple domain entity. In this post, I will demonstrate on working with domain entity with deep object graph, Service Layer and View Models and will also complete the rest of the demo application. In the previous post, we have done CRUD operations against Category entity and this post will be focus on Expense entity those have an association with Category entity. You can download the source code from http://efmvc.codeplex.com . The following frameworks will be used for this step by step tutorial.    1. ASP.NET MVC 3 RTM    2. EF Code First CTP 5    3. Unity 2.0 Domain Model Category Entity public class Category   {       public int CategoryId { get; set; }       [Required(ErrorMessage = "Name Required")]       [StringLength(25, ErrorMessage = "Must be less than 25 characters")]       public string Name { get; set;}       public string Description { get; set; }       public virtual ICollection<Expense> Expenses { get; set; }   } Expense Entity public class Expense     {                public int ExpenseId { get; set; }                public string  Transaction { get; set; }         public DateTime Date { get; set; }         public double Amount { get; set; }         public int CategoryId { get; set; }         public virtual Category Category { get; set; }     } We have two domain entities - Category and Expense. A single category contains a list of expense transactions and every expense transaction should have a Category. Repository class for Expense Transaction Let’s create repository class for handling CRUD operations for Expense entity public class ExpenseRepository : RepositoryBase<Expense>, IExpenseRepository     {     public ExpenseRepository(IDatabaseFactory databaseFactory)         : base(databaseFactory)         {         }                } public interface IExpenseRepository : IRepository<Expense> { } Service Layer If you are new to Service Layer, checkout Martin Fowler's article Service Layer . According to Martin Fowler, Service Layer defines an application's boundary and its set of available operations from the perspective of interfacing client layers. It encapsulates the application's business logic, controlling transactions and coordinating responses in the implementation of its operations. Controller classes should be lightweight and do not put much of business logic onto it. We can use the service layer as the business logic layer and can encapsulate the rules of the application. Let’s create a Service class for coordinates the transaction for Expense public interface IExpenseService {     IEnumerable<Expense> GetExpenses(DateTime startDate, DateTime ednDate);     Expense GetExpense(int id);             void CreateExpense(Expense expense);     void DeleteExpense(int id);     void SaveExpense(); } public class ExpenseService : IExpenseService {     private readonly IExpenseRepository expenseRepository;            private readonly IUnitOfWork unitOfWork;     public ExpenseService(IExpenseRepository expenseRepository, IUnitOfWork unitOfWork)     {                  this.expenseRepository = expenseRepository;         this.unitOfWork = unitOfWork;     }     public IEnumerable<Expense> GetExpenses(DateTime startDate, DateTime endDate)     {         var expenses = expenseRepository.GetMany(exp => exp.Date >= startDate && exp.Date <= endDate);         return expenses;     }     public void CreateExpense(Expense expense)     {         expenseRepository.Add(expense);         unitOfWork.Commit();     }     public Expense GetExpense(int id)     {         var expense = expenseRepository.GetById(id);         return expense;     }     public void DeleteExpense(int id)     {         var expense = expenseRepository.GetById(id);         expenseRepository.Delete(expense);         unitOfWork.Commit();     }     public void SaveExpense()     {         unitOfWork.Commit();     } }   View Model for Expense Transactions In real world ASP.NET MVC applications, we need to design model objects especially for our views. Our domain objects are mainly designed for the needs for domain model and it is representing the domain of our applications. On the other hand, View Model objects are designed for our needs for views. We have an Expense domain entity that has an association with Category. While we are creating a new Expense, we have to specify that in which Category belongs with the new Expense transaction. The user interface for Expense transaction will have form fields for representing the Expense entity and a CategoryId for representing the Category. So let's create view model for representing the need for Expense transactions. public class ExpenseViewModel {     public int ExpenseId { get; set; }       [Required(ErrorMessage = "Category Required")]     public int CategoryId { get; set; }       [Required(ErrorMessage = "Transaction Required")]     public string Transaction { get; set; }       [Required(ErrorMessage = "Date Required")]     public DateTime Date { get; set; }       [Required(ErrorMessage = "Amount Required")]     public double Amount { get; set; }       public IEnumerable<SelectListItem> Category { get; set; } } The ExpenseViewModel is designed for the purpose of View template and contains the all validation rules. It has properties for mapping values to Expense entity and a property Category for binding values to a drop-down for list values of Category. Create Expense transaction Let’s create action methods in the ExpenseController for creating expense transactions public ActionResult Create() {     var expenseModel = new ExpenseViewModel();     var categories = categoryService.GetCategories();     expenseModel.Category = categories.ToSelectListItems(-1);     expenseModel.Date = DateTime.Today;     return View(expenseModel); } [HttpPost] public ActionResult Create(ExpenseViewModel expenseViewModel) {                      if (!ModelState.IsValid)         {             var categories = categoryService.GetCategories();             expenseViewModel.Category = categories.ToSelectListItems(expenseViewModel.CategoryId);             return View("Save", expenseViewModel);         }         Expense expense=new Expense();         ModelCopier.CopyModel(expenseViewModel,expense);         expenseService.CreateExpense(expense);         return RedirectToAction("Index");              } In the Create action method for HttpGet request, we have created an instance of our View Model ExpenseViewModel with Category information for the drop-down list and passing the Model object to View template. The extension method ToSelectListItems is shown below   public static IEnumerable<SelectListItem> ToSelectListItems(         this IEnumerable<Category> categories, int  selectedId) {     return           categories.OrderBy(category => category.Name)                 .Select(category =>                     new SelectListItem                     {                         Selected = (category.CategoryId == selectedId),                         Text = category.Name,                         Value = category.CategoryId.ToString()                     }); } In the Create action method for HttpPost, our view model object ExpenseViewModel will map with posted form input values. We need to create an instance of Expense for the persistence purpose. So we need to copy values from ExpenseViewModel object to Expense object. ASP.NET MVC futures assembly provides a static class ModelCopier that can use for copying values between Model objects. ModelCopier class has two static methods - CopyCollection and CopyModel.CopyCollection method will copy values between two collection objects and CopyModel will copy values between two model objects. We have used CopyModel method of ModelCopier class for copying values from expenseViewModel object to expense object. Finally we did a call to CreateExpense method of ExpenseService class for persisting new expense transaction. List Expense Transactions We want to list expense transactions based on a date range. So let’s create action method for filtering expense transactions with a specified date range. public ActionResult Index(DateTime? startDate, DateTime? endDate) {     //If date is not passed, take current month's first and last dte     DateTime dtNow;     dtNow = DateTime.Today;     if (!startDate.HasValue)     {         startDate = new DateTime(dtNow.Year, dtNow.Month, 1);         endDate = startDate.Value.AddMonths(1).AddDays(-1);     }     //take last date of start date's month, if end date is not passed     if (startDate.HasValue && !endDate.HasValue)     {         endDate = (new DateTime(startDate.Value.Year, startDate.Value.Month, 1)).AddMonths(1).AddDays(-1);     }     var expenses = expenseService.GetExpenses(startDate.Value ,endDate.Value);     //if request is Ajax will return partial view     if (Request.IsAjaxRequest())     {         return PartialView("ExpenseList", expenses);     }     //set start date and end date to ViewBag dictionary     ViewBag.StartDate = startDate.Value.ToShortDateString();     ViewBag.EndDate = endDate.Value.ToShortDateString();     //if request is not ajax     return View(expenses); } We are using the above Index Action method for both Ajax requests and normal requests. If there is a request for Ajax, we will call the PartialView ExpenseList. Razor Views for listing Expense information Let’s create view templates in Razor for showing list of Expense information ExpenseList.cshtml @model IEnumerable<MyFinance.Domain.Expense>   <table>         <tr>             <th>Actions</th>             <th>Category</th>             <th>                 Transaction             </th>             <th>                 Date             </th>             <th>                 Amount             </th>         </tr>       @foreach (var item in Model) {              <tr>             <td>                 @Html.ActionLink("Edit", "Edit",new { id = item.ExpenseId })                 @Ajax.ActionLink("Delete", "Delete", new { id = item.ExpenseId }, new AjaxOptions { Confirm = "Delete Expense?", HttpMethod = "Post", UpdateTargetId = "divExpenseList" })             </td>              <td>                 @item.Category.Name             </td>             <td>                 @item.Transaction             </td>             <td>                 @String.Format("{0:d}", item.Date)             </td>             <td>                 @String.Format("{0:F}", item.Amount)             </td>         </tr>          }       </table>     <p>         @Html.ActionLink("Create New Expense", "Create") |         @Html.ActionLink("Create New Category", "Create","Category")     </p> Index.cshtml @using MyFinance.Helpers; @model IEnumerable<MyFinance.Domain.Expense> @{     ViewBag.Title = "Index"; }    <h2>Expense List</h2>    <script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.min.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/jquery-ui.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/jquery.ui.datepicker.js")" type="text/javascript"></script> <link href="@Url.Content("~/Content/jquery-ui-1.8.6.custom.css")" rel="stylesheet" type="text/css" />      @using (Ajax.BeginForm(new AjaxOptions{ UpdateTargetId="divExpenseList", HttpMethod="Get"})) {     <table>         <tr>         <td>         <div>           Start Date: @Html.TextBox("StartDate", Html.Encode(String.Format("{0:mm/dd/yyyy}", ViewData["StartDate"].ToString())), new { @class = "ui-datepicker" })         </div>         </td>         <td><div>            End Date: @Html.TextBox("EndDate", Html.Encode(String.Format("{0:mm/dd/yyyy}", ViewData["EndDate"].ToString())), new { @class = "ui-datepicker" })          </div></td>          <td> <input type="submit" value="Search By TransactionDate" /></td>         </tr>     </table>         }   <div id="divExpenseList">             @Html.Partial("ExpenseList", Model)     </div> <script type="text/javascript">     $().ready(function () {         $('.ui-datepicker').datepicker({             dateFormat: 'mm/dd/yy',             buttonImage: '@Url.Content("~/Content/calendar.gif")',             buttonImageOnly: true,             showOn: "button"         });     }); </script> Ajax search functionality using Ajax.BeginForm The search functionality of Index view is providing Ajax functionality using Ajax.BeginForm. The Ajax.BeginForm() method writes an opening <form> tag to the response. You can use this method in a using block. In that case, the method renders the closing </form> tag at the end of the using block and the form is submitted asynchronously by using JavaScript. The search functionality will call the Index Action method and this will return partial view ExpenseList for updating the search result. We want to update the response UI for the Ajax request onto divExpenseList element. So we have specified the UpdateTargetId as "divExpenseList" in the Ajax.BeginForm method. Add jQuery DatePicker Our search functionality is using a date range so we are providing two date pickers using jQuery datepicker. You need to add reference to the following JavaScript files to working with jQuery datepicker. jquery-ui.js jquery.ui.datepicker.js For theme support for datepicker, we can use a customized CSS class. In our example we have used a CSS file “jquery-ui-1.8.6.custom.css”. For more details about the datepicker component, visit jquery UI website at http://jqueryui.com/demos/datepicker . In the jQuery ready event, we have used following JavaScript function to initialize the UI element to show date picker. <script type="text/javascript">     $().ready(function () {         $('.ui-datepicker').datepicker({             dateFormat: 'mm/dd/yy',             buttonImage: '@Url.Content("~/Content/calendar.gif")',             buttonImageOnly: true,             showOn: "button"         });     }); </script>   Source Code You can download the source code from http://efmvc.codeplex.com/ . Summary In this two-part series, we have created a simple web application using ASP.NET MVC 3 RTM, Razor and EF Code First CTP 5. I have demonstrated patterns and practices  such as Dependency Injection, Repository pattern, Unit of Work, ViewModel and Service Layer. My primary objective was to demonstrate different practices and options for developing web apps using ASP.NET MVC 3 and EF Code First. You can implement these approaches in your own way for building web apps using ASP.NET MVC 3. I will refactor this demo app on later time.

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  • Sorting Algorithms

    - by MarkPearl
    General Every time I go back to university I find myself wading through sorting algorithms and their implementation in C++. Up to now I haven’t really appreciated their true value. However as I discovered this last week with Dictionaries in C# – having a knowledge of some basic programming principles can greatly improve the performance of a system and make one think twice about how to tackle a problem. I’m going to cover briefly in this post the following: Selection Sort Insertion Sort Shellsort Quicksort Mergesort Heapsort (not complete) Selection Sort Array based selection sort is a simple approach to sorting an unsorted array. Simply put, it repeats two basic steps to achieve a sorted collection. It starts with a collection of data and repeatedly parses it, each time sorting out one element and reducing the size of the next iteration of parsed data by one. So the first iteration would go something like this… Go through the entire array of data and find the lowest value Place the value at the front of the array The second iteration would go something like this… Go through the array from position two (position one has already been sorted with the smallest value) and find the next lowest value in the array. Place the value at the second position in the array This process would be completed until the entire array had been sorted. A positive about selection sort is that it does not make many item movements. In fact, in a worst case scenario every items is only moved once. Selection sort is however a comparison intensive sort. If you had 10 items in a collection, just to parse the collection you would have 10+9+8+7+6+5+4+3+2=54 comparisons to sort regardless of how sorted the collection was to start with. If you think about it, if you applied selection sort to a collection already sorted, you would still perform relatively the same number of iterations as if it was not sorted at all. Many of the following algorithms try and reduce the number of comparisons if the list is already sorted – leaving one with a best case and worst case scenario for comparisons. Likewise different approaches have different levels of item movement. Depending on what is more expensive, one may give priority to one approach compared to another based on what is more expensive, a comparison or a item move. Insertion Sort Insertion sort tries to reduce the number of key comparisons it performs compared to selection sort by not “doing anything” if things are sorted. Assume you had an collection of numbers in the following order… 10 18 25 30 23 17 45 35 There are 8 elements in the list. If we were to start at the front of the list – 10 18 25 & 30 are already sorted. Element 5 (23) however is smaller than element 4 (30) and so needs to be repositioned. We do this by copying the value at element 5 to a temporary holder, and then begin shifting the elements before it up one. So… Element 5 would be copied to a temporary holder 10 18 25 30 23 17 45 35 – T 23 Element 4 would shift to Element 5 10 18 25 30 30 17 45 35 – T 23 Element 3 would shift to Element 4 10 18 25 25 30 17 45 35 – T 23 Element 2 (18) is smaller than the temporary holder so we put the temporary holder value into Element 3. 10 18 23 25 30 17 45 35 – T 23   We now have a sorted list up to element 6. And so we would repeat the same process by moving element 6 to a temporary value and then shifting everything up by one from element 2 to element 5. As you can see, one major setback for this technique is the shifting values up one – this is because up to now we have been considering the collection to be an array. If however the collection was a linked list, we would not need to shift values up, but merely remove the link from the unsorted value and “reinsert” it in a sorted position. Which would reduce the number of transactions performed on the collection. So.. Insertion sort seems to perform better than selection sort – however an implementation is slightly more complicated. This is typical with most sorting algorithms – generally, greater performance leads to greater complexity. Also, insertion sort performs better if a collection of data is already sorted. If for instance you were handed a sorted collection of size n, then only n number of comparisons would need to be performed to verify that it is sorted. It’s important to note that insertion sort (array based) performs a number item moves – every time an item is “out of place” several items before it get shifted up. Shellsort – Diminishing Increment Sort So up to now we have covered Selection Sort & Insertion Sort. Selection Sort makes many comparisons and insertion sort (with an array) has the potential of making many item movements. Shellsort is an approach that takes the normal insertion sort and tries to reduce the number of item movements. In Shellsort, elements in a collection are viewed as sub-collections of a particular size. Each sub-collection is sorted so that the elements that are far apart move closer to their final position. Suppose we had a collection of 15 elements… 10 20 15 45 36 48 7 60 18 50 2 19 43 30 55 First we may view the collection as 7 sub-collections and sort each sublist, lets say at intervals of 7 10 60 55 – 20 18 – 15 50 – 45 2 – 36 19 – 48 43 – 7 30 10 55 60 – 18 20 – 15 50 – 2 45 – 19 36 – 43 48 – 7 30 (Sorted) We then sort each sublist at a smaller inter – lets say 4 10 55 60 18 – 20 15 50 2 – 45 19 36 43 – 48 7 30 10 18 55 60 – 2 15 20 50 – 19 36 43 45 – 7 30 48 (Sorted) We then sort elements at a distance of 1 (i.e. we apply a normal insertion sort) 10 18 55 60 2 15 20 50 19 36 43 45 7 30 48 2 7 10 15 18 19 20 30 36 43 45 48 50 55 (Sorted) The important thing with shellsort is deciding on the increment sequence of each sub-collection. From what I can tell, there isn’t any definitive method and depending on the order of your elements, different increment sequences may perform better than others. There are however certain increment sequences that you may want to avoid. An even based increment sequence (e.g. 2 4 8 16 32 …) should typically be avoided because it does not allow for even elements to be compared with odd elements until the final sort phase – which in a way would negate many of the benefits of using sub-collections. The performance on the number of comparisons and item movements of Shellsort is hard to determine, however it is considered to be considerably better than the normal insertion sort. Quicksort Quicksort uses a divide and conquer approach to sort a collection of items. The collection is divided into two sub-collections – and the two sub-collections are sorted and combined into one list in such a way that the combined list is sorted. The algorithm is in general pseudo code below… Divide the collection into two sub-collections Quicksort the lower sub-collection Quicksort the upper sub-collection Combine the lower & upper sub-collection together As hinted at above, quicksort uses recursion in its implementation. The real trick with quicksort is to get the lower and upper sub-collections to be of equal size. The size of a sub-collection is determined by what value the pivot is. Once a pivot is determined, one would partition to sub-collections and then repeat the process on each sub collection until you reach the base case. With quicksort, the work is done when dividing the sub-collections into lower & upper collections. The actual combining of the lower & upper sub-collections at the end is relatively simple since every element in the lower sub-collection is smaller than the smallest element in the upper sub-collection. Mergesort With quicksort, the average-case complexity was O(nlog2n) however the worst case complexity was still O(N*N). Mergesort improves on quicksort by always having a complexity of O(nlog2n) regardless of the best or worst case. So how does it do this? Mergesort makes use of the divide and conquer approach to partition a collection into two sub-collections. It then sorts each sub-collection and combines the sorted sub-collections into one sorted collection. The general algorithm for mergesort is as follows… Divide the collection into two sub-collections Mergesort the first sub-collection Mergesort the second sub-collection Merge the first sub-collection and the second sub-collection As you can see.. it still pretty much looks like quicksort – so lets see where it differs… Firstly, mergesort differs from quicksort in how it partitions the sub-collections. Instead of having a pivot – merge sort partitions each sub-collection based on size so that the first and second sub-collection of relatively the same size. This dividing keeps getting repeated until the sub-collections are the size of a single element. If a sub-collection is one element in size – it is now sorted! So the trick is how do we put all these sub-collections together so that they maintain their sorted order. Sorted sub-collections are merged into a sorted collection by comparing the elements of the sub-collection and then adjusting the sorted collection. Lets have a look at a few examples… Assume 2 sub-collections with 1 element each 10 & 20 Compare the first element of the first sub-collection with the first element of the second sub-collection. Take the smallest of the two and place it as the first element in the sorted collection. In this scenario 10 is smaller than 20 so 10 is taken from sub-collection 1 leaving that sub-collection empty, which means by default the next smallest element is in sub-collection 2 (20). So the sorted collection would be 10 20 Lets assume 2 sub-collections with 2 elements each 10 20 & 15 19 So… again we would Compare 10 with 15 – 10 is the winner so we add it to our sorted collection (10) leaving us with 20 & 15 19 Compare 20 with 15 – 15 is the winner so we add it to our sorted collection (10 15) leaving us with 20 & 19 Compare 20 with 19 – 19 is the winner so we add it to our sorted collection (10 15 19) leaving us with 20 & _ 20 is by default the winner so our sorted collection is 10 15 19 20. Make sense? Heapsort (still needs to be completed) So by now I am tired of sorting algorithms and trying to remember why they were so important. I think every year I go through this stuff I wonder to myself why are we made to learn about selection sort and insertion sort if they are so bad – why didn’t we just skip to Mergesort & Quicksort. I guess the only explanation I have for this is that sometimes you learn things so that you can implement them in future – and other times you learn things so that you know it isn’t the best way of implementing things and that you don’t need to implement it in future. Anyhow… luckily this is going to be the last one of my sorts for today. The first step in heapsort is to convert a collection of data into a heap. After the data is converted into a heap, sorting begins… So what is the definition of a heap? If we have to convert a collection of data into a heap, how do we know when it is a heap and when it is not? The definition of a heap is as follows: A heap is a list in which each element contains a key, such that the key in the element at position k in the list is at least as large as the key in the element at position 2k +1 (if it exists) and 2k + 2 (if it exists). Does that make sense? At first glance I’m thinking what the heck??? But then after re-reading my notes I see that we are doing something different – up to now we have really looked at data as an array or sequential collection of data that we need to sort – a heap represents data in a slightly different way – although the data is stored in a sequential collection, for a sequential collection of data to be in a valid heap – it is “semi sorted”. Let me try and explain a bit further with an example… Example 1 of Potential Heap Data Assume we had a collection of numbers as follows 1[1] 2[2] 3[3] 4[4] 5[5] 6[6] For this to be a valid heap element with value of 1 at position [1] needs to be greater or equal to the element at position [3] (2k +1) and position [4] (2k +2). So in the above example, the collection of numbers is not in a valid heap. Example 2 of Potential Heap Data Lets look at another collection of numbers as follows 6[1] 5[2] 4[3] 3[4] 2[5] 1[6] Is this a valid heap? Well… element with the value 6 at position 1 must be greater or equal to the element at position [3] and position [4]. Is 6 > 4 and 6 > 3? Yes it is. Lets look at element 5 as position 2. It must be greater than the values at [4] & [5]. Is 5 > 3 and 5 > 2? Yes it is. If you continued to examine this second collection of data you would find that it is in a valid heap based on the definition of a heap.

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  • Using the Data Form Web Part (SharePoint 2010) Site Agnostically!

    - by David Jacobus
    Originally posted on: http://geekswithblogs.net/djacobus/archive/2013/10/24/154465.aspxAs a Developer whom has worked closely with web designers (Power users) in a SharePoint environment, I have come across the issue of making the Data Form Web Part reusable across the site collection! In SharePoint 2007 it was very easy and this blog pointed the way to make it happen: Josh Gaffey's Blog. In SharePoint 2010 something changed! This method failed except for using a Data Form Web Part that pointed to a list in the Site Collection Root! I am making this discussion relative to a developer whom creates a solution (WSP) with all the artifacts embedded and the user shouldn’t have any involvement in the process except to activate features. The Scenario: 1. A Power User creates a Data Form Web Part using SharePoint Designer 2010! It is a great web part the uses all the power of SharePoint Designer and XSLT (Conditional formatting, etc.). 2. Other Users in the site collection want to use that specific web part in sub sites in the site collection. Pointing to a list with the same name, not at the site collection root! The Issues: 1. The Data Form Web Part Data Source uses a List ID (GUID) to point to the specific list. Which means a list in a sub site will have a list with a new GUID different than the one which was created with SharePoint Designer! Obviously, the List needs to be the same List (Fields, Content Types, etc.) with different data. 2. How can we make this web part site agnostic, and dependent only on the lists Name? I had this problem come up over and over and decided to put my solution forward! The Solution: 1. Use the XSL of the Data Form Web Part Created By the Power User in SharePoint Designer! 2. Extend the OOTB Data Form Web Part to use this XSL and Point to a List by name. The solution points to a hybrid solution that requires some coding (Developer) and the XSL (Power User) artifacts put together in a Visual Studio SharePoint Solution. Here are the solution steps in summary: 1. Create an empty SharePoint project in Visual Studio 2. Create a Module and Feature and put the XSL file created by the Power User into it a. Scope the feature to web 3. Create a Feature Receiver to Create the List. The same list from which the Data Form Web Part was created with by the Power User. a. Scope the feature to web 4. Create a Web Part extending the Data Form Web a. Point the Data Form Web Part to point to the List by Name b. Point the Data Form Web Part XSL link to the XSL added using the Module feature c. Scope The feature to Site i. This is because all web parts are in the site collection web part gallery. So in a Narrative Summary: We are creating a list in code which has the same name and (site Columns) as the list from which the Power User created the Data Form Web Part Using SharePoint Designer. We are creating a Web Part in code which extends the OOTB Data Form Web Part to point to a list by name and use the XSL created by the Power User. Okay! Here are the steps with images and code! At the end of this post I will provide a link to the code for a solution which works in any site! I want to TOOT the HORN for the power of this solution! It is the mantra a use with all my clients! What is a basic skill a SharePoint Developer: Create an application that uses the data from a SharePoint list and make that data visible to the user in a manner which meets requirements! Create an Empty SharePoint 2010 Project Here I am naming my Project DJ.DataFormWebPart Create a Code Folder Copy and paste the Extension and Utilities classes (Found in the solution provided at the end of this post) Change the Namespace to match this project The List to which the Data Form Web Part which was used to make the XSL by the Power User in SharePoint Designer is now going to be created in code! If already in code, then all the better! Here I am going to create a list in the site collection root and add some data to it! For the purpose of this discussion I will actually create this list in code before using SharePoint Designer for simplicity! So here I create the List and deploy it within this solution before I do anything else. I will use a List I created before for demo purposes. Footer List is used within the footer of my master page. Add a new Feature: Here I name the Feature FooterList and add a Feature Event Receiver: Here is the code for the Event Receiver: I have a previous blog post about adding lists in code so I will not take time to narrate this code: using System; using System.Runtime.InteropServices; using System.Security.Permissions; using Microsoft.SharePoint; using DJ.DataFormWebPart.Code; namespace DJ.DataFormWebPart.Features.FooterList { /// <summary> /// This class handles events raised during feature activation, deactivation, installation, uninstallation, and upgrade. /// </summary> /// <remarks> /// The GUID attached to this class may be used during packaging and should not be modified. /// </remarks> [Guid("a58644fd-9209-41f4-aa16-67a53af7a9bf")] public class FooterListEventReceiver : SPFeatureReceiver { SPWeb currentWeb = null; SPSite currentSite = null; const string columnGroup = "DJ"; const string ctName = "FooterContentType"; // Uncomment the method below to handle the event raised after a feature has been activated. public override void FeatureActivated(SPFeatureReceiverProperties properties) { using (SPWeb spWeb = properties.GetWeb() as SPWeb) { using (SPSite site = new SPSite(spWeb.Site.ID)) { using (SPWeb rootWeb = site.OpenWeb(site.RootWeb.ID)) { //add the fields addFields(rootWeb); //add content type SPContentType testCT = rootWeb.ContentTypes[ctName]; // we will not create the content type if it exists if (testCT == null) { //the content type does not exist add it addContentType(rootWeb, ctName); } if ((spWeb.Lists.TryGetList("FooterList") == null)) { //create the list if it dosen't to exist CreateFooterList(spWeb, site); } } } } } #region ContentType public void addFields(SPWeb spWeb) { Utilities.addField(spWeb, "Link", SPFieldType.URL, false, columnGroup); Utilities.addField(spWeb, "Information", SPFieldType.Text, false, columnGroup); } private static void addContentType(SPWeb spWeb, string name) { SPContentType myContentType = new SPContentType(spWeb.ContentTypes["Item"], spWeb.ContentTypes, name) { Group = columnGroup }; spWeb.ContentTypes.Add(myContentType); addContentTypeLinkages(spWeb, myContentType); myContentType.Update(); } public static void addContentTypeLinkages(SPWeb spWeb, SPContentType ct) { Utilities.addContentTypeLink(spWeb, "Link", ct); Utilities.addContentTypeLink(spWeb, "Information", ct); } private void CreateFooterList(SPWeb web, SPSite site) { Guid newListGuid = web.Lists.Add("FooterList", "Footer List", SPListTemplateType.GenericList); SPList newList = web.Lists[newListGuid]; newList.ContentTypesEnabled = true; var footer = site.RootWeb.ContentTypes[ctName]; newList.ContentTypes.Add(footer); newList.ContentTypes.Delete(newList.ContentTypes["Item"].Id); newList.Update(); var view = newList.DefaultView; //add all view fields here //view.ViewFields.Add("NewsTitle"); view.ViewFields.Add("Link"); view.ViewFields.Add("Information"); view.Update(); } } } Basically created a content type with two site columns Link and Information. I had to change some code as we are working at the SPWeb level and need Content Types at the SPSite level! I’ll use a new Site Collection for this demo (Best Practice) keep old artifacts from impinging on development: Next we will add this list to the root of the site collection by deploying this solution, add some data and then use SharePoint Designer to create a Data Form Web Part. The list has been added, now let’s add some data: Okay let’s add a Data Form Web Part in SharePoint Designer. Create a new web part page in the site pages library: I will name it TestWP.aspx and edit it in advanced mode: Let’s add an empty Data Form Web Part to the web part zone: Click on the web part to add a data source: Choose FooterList in the Data Source menu: Choose appropriate fields and select insert as multiple item view: Here is what it look like after insertion: Let’s add some conditional formatting if the information filed is not blank: Choose Create (right side) apply formatting: Choose the Information Field and set the condition not null: Click Set Style: Here is the result: Okay! Not flashy but simple enough for this demo. Remember this is the job of the Power user! All we want from this web part is the XLS-Style Sheet out of SharePoint Designer. We are going to use it as the XSL for our web part which we will be creating next. Let’s add a web part to our project extending the OOTB Data Form Web Part. Add new item from the Visual Studio add menu: Choose Web Part: Change WebPart to DataFormWebPart (Oh well my namespace needs some improvement, but it will sure make it readily identifiable as an extended web part!) Below is the code for this web part: using System; using System.ComponentModel; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using Microsoft.SharePoint; using Microsoft.SharePoint.WebControls; using System.Text; namespace DJ.DataFormWebPart.DataFormWebPart { [ToolboxItemAttribute(false)] public class DataFormWebPart : Microsoft.SharePoint.WebPartPages.DataFormWebPart { protected override void OnInit(EventArgs e) { base.OnInit(e); this.ChromeType = PartChromeType.None; this.Title = "FooterListDF"; try { //SPSite site = SPContext.Current.Site; SPWeb web = SPContext.Current.Web; SPList list = web.Lists.TryGetList("FooterList"); if (list != null) { string queryList1 = "<Query><Where><IsNotNull><FieldRef Name='Title' /></IsNotNull></Where><OrderBy><FieldRef Name='Title' Ascending='True' /></OrderBy></Query>"; uint maximumRowList1 = 10; SPDataSource dataSourceList1 = GetDataSource(list.Title, web.Url, list, queryList1, maximumRowList1); this.DataSources.Add(dataSourceList1); this.XslLink = web.Url + "/Assests/Footer.xsl"; this.ParameterBindings = BuildDataFormParameters(); this.DataBind(); } } catch (Exception ex) { this.Controls.Add(new LiteralControl("ERROR: " + ex.Message)); } } private SPDataSource GetDataSource(string dataSourceId, string webUrl, SPList list, string query, uint maximumRow) { SPDataSource dataSource = new SPDataSource(); dataSource.UseInternalName = true; dataSource.ID = dataSourceId; dataSource.DataSourceMode = SPDataSourceMode.List; dataSource.List = list; dataSource.SelectCommand = "" + query + ""; Parameter listIdParam = new Parameter("ListID"); listIdParam.DefaultValue = list.ID.ToString( "B").ToUpper(); Parameter maximumRowsParam = new Parameter("MaximumRows"); maximumRowsParam.DefaultValue = maximumRow.ToString(); QueryStringParameter rootFolderParam = new QueryStringParameter("RootFolder", "RootFolder"); dataSource.SelectParameters.Add(listIdParam); dataSource.SelectParameters.Add(maximumRowsParam); dataSource.SelectParameters.Add(rootFolderParam); dataSource.UpdateParameters.Add(listIdParam); dataSource.DeleteParameters.Add(listIdParam); dataSource.InsertParameters.Add(listIdParam); return dataSource; } private string BuildDataFormParameters() { StringBuilder parameters = new StringBuilder("<ParameterBindings><ParameterBinding Name=\"dvt_apos\" Location=\"Postback;Connection\"/><ParameterBinding Name=\"UserID\" Location=\"CAMLVariable\" DefaultValue=\"CurrentUserName\"/><ParameterBinding Name=\"Today\" Location=\"CAMLVariable\" DefaultValue=\"CurrentDate\"/>"); parameters.Append("<ParameterBinding Name=\"dvt_firstrow\" Location=\"Postback;Connection\"/>"); parameters.Append("<ParameterBinding Name=\"dvt_nextpagedata\" Location=\"Postback;Connection\"/>"); parameters.Append("<ParameterBinding Name=\"dvt_adhocmode\" Location=\"Postback;Connection\"/>"); parameters.Append("<ParameterBinding Name=\"dvt_adhocfiltermode\" Location=\"Postback;Connection\"/>"); parameters.Append("</ParameterBindings>"); return parameters.ToString(); } } } The OnInit method we use to set the list name and the XSL Link property of the Data Form Web Part. We do not have the link to XSL in our Solution so we will add the XSL now: Add a Module in the Visual Studio add menu: Rename Sample.txt in the module to footer.xsl and then copy the XSL from SharePoint Designer Look at elements.xml to where the footer.xsl is being provisioned to which is Assets/footer.xsl, make sure the Web parts xsl link is pointing to this url: Okay we are good to go! Let’s check our features and package: DataFormWebPart should be scoped to site and have the web part: The Footer List feature should be scoped to web and have the Assets module (Okay, I see, a spelling issue but it won’t affect this demo) If everything is correct we should be able to click a couple of sub site feature activations and have our list and web part in a sub site. (In fact this solution can be activated anywhere) Here is the list created at SubSite1 with new data It. Next let’s add the web part on a test page and see if it works as expected: It does! So we now have a repeatable way to use a WSP to move a Data Form Web Part around our sites! Here is a link to the code: DataFormWebPart Solution

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  • A Communication System for XAML Applications

    - by psheriff
    In any application, you want to keep the coupling between any two or more objects as loose as possible. Coupling happens when one class contains a property that is used in another class, or uses another class in one of its methods. If you have this situation, then this is called strong or tight coupling. One popular design pattern to help with keeping objects loosely coupled is called the Mediator design pattern. The basics of this pattern are very simple; avoid one object directly talking to another object, and instead use another class to mediate between the two. As with most of my blog posts, the purpose is to introduce you to a simple approach to using a message broker, not all of the fine details. IPDSAMessageBroker Interface As with most implementations of a design pattern, you typically start with an interface or an abstract base class. In this particular instance, an Interface will work just fine. The interface for our Message Broker class just contains a single method “SendMessage” and one event “MessageReceived”. public delegate void MessageReceivedEventHandler( object sender, PDSAMessageBrokerEventArgs e); public interface IPDSAMessageBroker{  void SendMessage(PDSAMessageBrokerMessage msg);   event MessageReceivedEventHandler MessageReceived;} PDSAMessageBrokerMessage Class As you can see in the interface, the SendMessage method requires a type of PDSAMessageBrokerMessage to be passed to it. This class simply has a MessageName which is a ‘string’ type and a MessageBody property which is of the type ‘object’ so you can pass whatever you want in the body. You might pass a string in the body, or a complete Customer object. The MessageName property will help the receiver of the message know what is in the MessageBody property. public class PDSAMessageBrokerMessage{  public PDSAMessageBrokerMessage()  {  }   public PDSAMessageBrokerMessage(string name, object body)  {    MessageName = name;    MessageBody = body;  }   public string MessageName { get; set; }   public object MessageBody { get; set; }} PDSAMessageBrokerEventArgs Class As our message broker class will be raising an event that others can respond to, it is a good idea to create your own event argument class. This class will inherit from the System.EventArgs class and add a couple of additional properties. The properties are the MessageName and Message. The MessageName property is simply a string value. The Message property is a type of a PDSAMessageBrokerMessage class. public class PDSAMessageBrokerEventArgs : EventArgs{  public PDSAMessageBrokerEventArgs()  {  }   public PDSAMessageBrokerEventArgs(string name,     PDSAMessageBrokerMessage msg)  {    MessageName = name;    Message = msg;  }   public string MessageName { get; set; }   public PDSAMessageBrokerMessage Message { get; set; }} PDSAMessageBroker Class Now that you have an interface class and a class to pass a message through an event, it is time to create your actual PDSAMessageBroker class. This class implements the SendMessage method and will also create the event handler for the delegate created in your Interface. public class PDSAMessageBroker : IPDSAMessageBroker{  public void SendMessage(PDSAMessageBrokerMessage msg)  {    PDSAMessageBrokerEventArgs args;     args = new PDSAMessageBrokerEventArgs(      msg.MessageName, msg);     RaiseMessageReceived(args);  }   public event MessageReceivedEventHandler MessageReceived;   protected void RaiseMessageReceived(    PDSAMessageBrokerEventArgs e)  {    if (null != MessageReceived)      MessageReceived(this, e);  }} The SendMessage method will take a PDSAMessageBrokerMessage object as an argument. It then creates an instance of a PDSAMessageBrokerEventArgs class, passing to the constructor two items: the MessageName from the PDSAMessageBrokerMessage object and also the object itself. It may seem a little redundant to pass in the message name when that same message name is part of the message, but it does make consuming the event and checking for the message name a little cleaner – as you will see in the next section. Create a Global Message Broker In your WPF application, create an instance of this message broker class in the App class located in the App.xaml file. Create a public property in the App class and create a new instance of that class in the OnStartUp event procedure as shown in the following code: public partial class App : Application{  public PDSAMessageBroker MessageBroker { get; set; }   protected override void OnStartup(StartupEventArgs e)  {    base.OnStartup(e);     MessageBroker = new PDSAMessageBroker();  }} Sending and Receiving Messages Let’s assume you have a user control that you load into a control on your main window and you want to send a message from that user control to the main window. You might have the main window display a message box, or put a string into a status bar as shown in Figure 1. Figure 1: The main window can receive and send messages The first thing you do in the main window is to hook up an event procedure to the MessageReceived event of the global message broker. This is done in the constructor of the main window: public MainWindow(){  InitializeComponent();   (Application.Current as App).MessageBroker.     MessageReceived += new MessageReceivedEventHandler(       MessageBroker_MessageReceived);} One piece of code you might not be familiar with is accessing a property defined in the App class of your XAML application. Within the App.Xaml file is a class named App that inherits from the Application object. You access the global instance of this App class by using Application.Current. You cast Application.Current to ‘App’ prior to accessing any of the public properties or methods you defined in the App class. Thus, the code (Application.Current as App).MessageBroker, allows you to get at the MessageBroker property defined in the App class. In the MessageReceived event procedure in the main window (shown below) you can now check to see if the MessageName property of the PDSAMessageBrokerEventArgs is equal to “StatusBar” and if it is, then display the message body into the status bar text block control. void MessageBroker_MessageReceived(object sender,   PDSAMessageBrokerEventArgs e){  switch (e.MessageName)  {    case "StatusBar":      tbStatus.Text = e.Message.MessageBody.ToString();      break;  }} In the Page 1 user control’s Loaded event procedure you will send the message “StatusBar” through the global message broker to any listener using the following code: private void UserControl_Loaded(object sender,  RoutedEventArgs e){  // Send Status Message  (Application.Current as App).MessageBroker.    SendMessage(new PDSAMessageBrokerMessage("StatusBar",      "This is Page 1"));} Since the main window is listening for the message ‘StatusBar’, it will display the value “This is Page 1” in the status bar at the bottom of the main window. Sending a Message to a User Control The previous example sent a message from the user control to the main window. You can also send messages from the main window to any listener as well. Remember that the global message broker is really just a broadcaster to anyone who has hooked into the MessageReceived event. In the constructor of the user control named ucPage1 you can hook into the global message broker’s MessageReceived event. You can then listen for any messages that are sent to this control by using a similar switch-case structure like that in the main window. public ucPage1(){  InitializeComponent();   // Hook to the Global Message Broker  (Application.Current as App).MessageBroker.    MessageReceived += new MessageReceivedEventHandler(      MessageBroker_MessageReceived);} void MessageBroker_MessageReceived(object sender,  PDSAMessageBrokerEventArgs e){  // Look for messages intended for Page 1  switch (e.MessageName)  {    case "ForPage1":      MessageBox.Show(e.Message.MessageBody.ToString());      break;  }} Once the ucPage1 user control has been loaded into the main window you can then send a message using the following code: private void btnSendToPage1_Click(object sender,  RoutedEventArgs e){  PDSAMessageBrokerMessage arg =     new PDSAMessageBrokerMessage();   arg.MessageName = "ForPage1";  arg.MessageBody = "Message For Page 1";   // Send a message to Page 1  (Application.Current as App).MessageBroker.SendMessage(arg);} Since the MessageName matches what is in the ucPage1 MessageReceived event procedure, ucPage1 can do anything in response to that event. It is important to note that when the message gets sent it is sent to all MessageReceived event procedures, not just the one that is looking for a message called “ForPage1”. If the user control ucPage1 is not loaded and this message is broadcast, but no other code is listening for it, then it is simply ignored. Remove Event Handler In each class where you add an event handler to the MessageReceived event you need to make sure to remove those event handlers when you are done. Failure to do so can cause a strong reference to the class and thus not allow that object to be garbage collected. In each of your user control’s make sure in the Unloaded event to remove the event handler. private void UserControl_Unloaded(object sender, RoutedEventArgs e){  if (_MessageBroker != null)    _MessageBroker.MessageReceived -=         _MessageBroker_MessageReceived;} Problems with Message Brokering As with most “global” classes or classes that hook up events to other classes, garbage collection is something you need to consider. Just the simple act of hooking up an event procedure to a global event handler creates a reference between your user control and the message broker in the App class. This means that even when your user control is removed from your UI, the class will still be in memory because of the reference to the message broker. This can cause messages to still being handled even though the UI is not being displayed. It is up to you to make sure you remove those event handlers as discussed in the previous section. If you don’t, then the garbage collector cannot release those objects. Instead of using events to send messages from one object to another you might consider registering your objects with a central message broker. This message broker now becomes a collection class into which you pass an object and what messages that object wishes to receive. You do end up with the same problem however. You have to un-register your objects; otherwise they still stay in memory. To alleviate this problem you can look into using the WeakReference class as a method to store your objects so they can be garbage collected if need be. Discussing Weak References is beyond the scope of this post, but you can look this up on the web. Summary In this blog post you learned how to create a simple message broker system that will allow you to send messages from one object to another without having to reference objects directly. This does reduce the coupling between objects in your application. You do need to remember to get rid of any event handlers prior to your objects going out of scope or you run the risk of having memory leaks and events being called even though you can no longer access the object that is responding to that event. NOTE: You can download the sample code for this article by visiting my website at http://www.pdsa.com/downloads. Select “Tips & Tricks”, then select “A Communication System for XAML Applications” from the drop down list.

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